International Journal of Vehicle Design (79 papers in press)
Refined modelling of thin-walled beam, plate and joint for automobile frame
by Jiantao Bai, Wenjie Zuo
Abstract: At the conceptual design stage, the simplified frame is extensively applied in the body-in-white (BIW) structure to rapidly calculate its performances. However, it is difficult to acquire an accurate simplified frame of the BIW structure for the calculation of the bending stiffness, torsional stiffness and frequencies. This paper proposes a simplified modelling method by using the thin-walled beams (TWBs) with complex sections, semi-rigid elements and cross beam structures to create the simplified frame. Compared with the traditional modelling method, the TWBs contain more types of the complex section, the semi-rigid elements can describe various deformations, and the plate structures are further considered. Firstly, the properties of the complex sections are summarised. Especially, the torsional moments of inertia of the multi-cell sections are derived. Secondly, the semi-rigid beam element is reduced to a super element, which is composed of one beam element and three translational and three rotational springs. Among them, the spring stiffness of the semi-rigid element is obtained by solving the detailed finite element model of the TWBs, which can be accurately and rapidly solved by using this method. Thirdly, the cross beam structure is introduced to replace the plate structure by the equivalence of the mass and central deflection for the first time. This method can further improve the accuracy of the simplified frame. Lastly, a numerical example demonstrates that the simplified frame can accelerate the conceptual design of the BIW structure.
Keywords: conceptual design; frame structure; complex section; semi-rigid element; cross beam structure.
Marine predators algorithm and multi-verse optimization algorithm for optimal battery case design of electric vehicles
by Betül Sultan Yildiz
Abstract: This article focuses on the optimum design of a battery case of an electric racing car. Two recently developed metaheuristics, which are marine predators algorithm (MPA) and the multi-verse optimisation algorithm (MVO), are used to create an optimal design where the mass is considered as an objective function, and the geometric dimensions of the component are considered to be the design variables. The kriging surrogate modelling is used to obtain the proxy model to increase the efficiency of the optimisation. The results show the robustness of the MPA in the optimum design of the electric car components. The MPA can be used in other product development processes.
Keywords: marine predators algorithm; electric vehicles; battery case; shape design optimisation; multi-verse optimisation algorithm.
A novel design of a dry clutch pressure plate for weight reduction without compromising its thermo-mechanical performance
by Tolga Cakmak, Muhsin Kilic
Abstract: The main objective of this study is to conduct experimental research to investigate the effect of ventilation channels that have never been incorporated into the conventional automotive clutch pressure plate. The purpose is to reduce its weight without compromising its thermo-mechanical performance. Both convective and conductive heat transfers of the clutch pressure plate have been enhanced in order to meet thermo-mechanical performance requirements, by ventilation channels and by chemical composition adjustment, respectively. The novel design of ventilated
Keywords: dry clutch; heat transfer enhancement; weight reduction.
AUKF based unified estimation scheme for nonlinear vehicle dynamics
by Shouvik Chakraborty, Anindita Sengupta, Ashoke Sutradhar
Abstract: The paper presents an additive unscented Kalman filter (AUKF) based modular approach to estimate lateral vehicle dynamics and tyre forces. In this approach, a simplified single-track vehicular model and a dynamics-oriented tyre model are adopted to represent the vehicular motion. Subsequently, multiple observer modules for each dynamical state are designed and integrated into a Unified Estimation Scheme (UES-AUKF). Two additional non-modular observers using AUKF and EKF are designed for comparative analysis of estimation accuracy and computational efficiency of the designed scheme. The simplified model and the designed estimators are simulated using double lane change and sinusoidal manoeuvres for high and low surfaces, respectively, and the results are analysed. Thereby the scheme is further validated using real vehicle dataset for estimation accuracy. Simulation results for the simplified vehicle and the tyre model conform with the standard results with acceptable deviations. The proposed scheme exhibits improved accuracy with reduced computational time compared with the non-modular observers.
Keywords: UKF; vehicle dynamics; yaw rate; slip angle; tyre force; modular estimation; tyre model; lateral dynamics estimation; Kalman filter; bicycle model.
Development of a novel testing procedure and optimisation of a rubber spring using constrained simulated annealing algorithm for automobile clutch system
by Mehmet Onur Genç, Süleyman Konakçi, Necmettin Kaya, Samet Kartal, Ali Kamil Serbest
Abstract: Rubber compounds have widely used in many industry areas with many advantages, including in the automotive industry. However, the use of rubber-based springs within the clutch system of automobiles requires further investigation owing to the mechanical behaviour variations of rubber-based materials under dynamic conditions. In this study, a new methodology is proposed for the use of elastomer-based damper springs in automobile clutch systems. The design of the rubber damper spring and validation are comparatively investigated for an automobile clutch system, and a novel approach is developed. For this purpose, clutch usage on the automobile was simulated with a torsional fatigue test bench, which represents the loading and unloading case on damper springs at specific cycles and frequencies. NBR (nitrile rubber) was chosen as the sample rubber spring material, since it has representative material characteristics. As a result of the performed tests, a target stiffness value was obtained for the specified clutch requirements, and then a simulated annealing algorithm was coded in Python programming language and applied using specific design constraints from the response surface methodology.
Keywords: rubber damper; hyper-viscoelastic modelling; simulated annealing; torsional fatigue; clutch disc; powertrain system; system optimisation.
Dual-redundancy multi-mode control of high safety reliability steering wheel system
by Junnan Mi, Tong Wang, Xiaomin Lian
Abstract: The steering wheel system of a steer-by-wire system (SBW) offers steering torque to driver. In order to improve its safety and reliability, a dual-redundancy steering wheel system is proposed. This research proposes a dual-redundancy multi-mode control method for this system, which is divided into different control modes, namely the angle alignment mode, the pivot steer with resistance mode, and the uniform approach to middle position mode, so that the system can adapt to different vehicle running states and drivers manipulation habits. At the same time, a torque balance control method for two channel motors is proposed to balance their torques, and an order-reduce and reforming control method is proposed so that the system can still work even if one motor fails. Finally, this study built a vehicle test platform to verify the control method and prove its effectiveness.
Keywords: steer-by-wire; safety; steering wheel; redundancy; control; steering torque ;SBW.
Damage equivalent virtual tracks for motorcycles
by Aptin Haerian, Kemal Öztürk, Robert Liebich
Abstract: The present work deals with the topic of service loads for motorcycles resulting from road excitation. The aim is to create virtual test tracks that can be used representatively for load assumptions. First, different methods from the field of durability engineering are reviewed that centre around the topic of damage equivalency. The methods are evaluated in terms of applicability for virtual test tracks. With an omission approach, a novel method was found to detect relevant track segments for different use cases. The method was successfully applied to create virtual test tracks based on measurements of real tracks with laser scanners. With the proposed method the length of the test tracks and data amount could be decreased by approximately 70%. The gained perceptions enable a faster definition of design loads while additionally saving costs and reducing the amount of data during the early stages of development.
Keywords: virtual proving ground; multi-body simulation; motorcycle; durability; damage equivalency; omission approach.
Nonlinear vehicle active suspension system control method based on the extended high gain observer
by Qinghua Meng, Bingji Li, Chuan Hu
Abstract: In order to reduce the number of sensors used in the vehicle active suspension system and improve the ride comfort and handling stability, this paper proposes a novel vehicle active suspension control approach based on an extended high gain observer approach. Firstly, for facilitating the controller design, the underactuated active suspension dynamic model is transferred to a fully-actuated system dynamic model. Then the extended high gain observer (EHGO) is constructed to estimate the unknown states and uncertainties according to the state functions of the active suspension control system. An output feedback controller based on EHGO is designed to improve the vertical ride comfort and handling stability of the active suspension. Furthermore, the closed-loop system is analysed to prove the boundedness of all the states. The EHGO approach is proved to stabilise the active suspension by Lyapunov stability analysis. Simulation and experiment results verify the effectiveness of the designed controller.
Keywords: active suspension; extended high gain observer; underactuated system; Lyapunov stability analysis; nonlinear control.
Estimation method of vehicle sideslip angle considering coupled longitudinal and lateral dynamics
by Qian Zhang, Hongliang Zhou, Zhiyuang Liu, Linhui Zhao
Abstract: The coupled longitudinal and lateral dynamics control plays an important role in improving the vehicle motion performance. It is very complex to describe the lateral tyre force with a coupled longitudinal and lateral dynamics, thus making it difficult to establish a lateral dynamics model and design a sideslip angle observer. In this paper, based on the piecewise affine (PWA) description of the lateral force, a novel lateral dynamics modelling method is proposed considering coupled longitudinal dynamics. Firstly, a nominal PWA model of the lateral force is established. Secondly, by regarding the slip ratio and the dynamic load as varying parameters, we obtain a novel PWA lateral dynamics model which can describe the influence of the slip ratio on the lateral dynamics. Finally, the switched T-S observer is presented. Simulation results show the effectiveness of the proposed PWA model and the designed observer.
Keywords: coupled longitudinal and lateral dynamics; piecewise affine model; vehicle sideslip angle; lateral force; slip ratio; switched T-S observer.
Cool semantics of mini electric vehicles considering appearance attractive factors
by Le Xi, Su-nan Li, Hui Zhang, Jian-xin Cheng
Abstract: Today, the word cool has become a generic term to indicate approval and appreciation from audiences for a new design style of freshly released concept cars. To capture this cool style, this study investigated the appearance characteristics of mini electric vehicles (mini-EVs) using cool semantics. The cool semantic space of mini-EVs has been constructed through the cool-evaluation grid method (C-EGM), and the internal relationship between multiple cool semantics and appearance factors was identified by the quantitative analysis of quantification theory type I (QT-1). Then, satisfaction attributes of key factors extracted from QT-1 were subdivided by the fuzzy Kano model (FKM), to facilitate their adoption during the creation of designs by the designer. The results show that C-EGM and FKM can clearly deconstruct the concept and the essence of coolness products from multiple levels. Consequently, these can be used to promote the designers' accurate understanding of customer preferences of vehicle style and provide new ideas.
Keywords: cool semantics; attractive factor; evaluation grid method; Fuzzy-Kano model; quantification theory type I; mini electric vehicle.
Automotive airbag stiffness evaluation: a simulation-based conceptual design
by Javad Marzbanrad, Vahid Rastegar, Esmail Dehghani
Abstract: In this research, a model and a particle simulation method were used to analyse the stiffness of a fully deployed airbag that is related to the severity of the occupant injury in a frontal crash. First, a mathematical model based on a three-dimensional airbag geometry was introduced. Then, quasi-static and dynamic test setups were defined, including an external impactor to simulate an actual crash. A simulation was also designed by the corpuscular method with the same initial conditions to validate the airbag model and to assess the effect of parameters at the out-of-position impact. Finally, airbag stiffness characteristics were calculated for different airbag capacities and inflator performances as a function of internal pressure and volume. The evaluated time-dependent stiffness characteristics were linearized by the proposed method. The estimated coefficients were correlated to airbag geometry and inflator performance and can predict occupant injury in a high-speed crash.
Keywords: automotive airbag; in position; out of position; stiffness; linearization; corpuscular method; conceptual design; occupant safety; crash injury; inflator performance.
Optimisation design and performance evaluation of a novel dual-motor multi-mode coupling powertrain for electric vehicles
by Wei Du, Shengdun Zhao, Jingzhou Gao
Abstract: With a certain battery capacity, the mileage of an electric vehicle depends on the efficiency of the powertrain. In this paper, a novel dual-motor multi-mode coupling powertrain (DMMCP) is proposed. This paper compares it with the traditional powertrain composed of a single-motor and two-speed transmission (SMTSP). To make a fair comparison, the influence of component parameters on the powertrain must be considered. So this paper proposes a method that can evaluate the dynamic or economic performance at the same time as the parameter optimisation. Then the dynamic performance and economy of the two powertrains are evaluated. The results show that the dynamic performance and economy of DMMCP are better than SMTSP, so DMMCP has enormous development potential.
Keywords: dual-motor multi-mode coupling powertrain; electric vehicles; dynamic programming; NSGA_II.
Effect of inflation pressure on tire forces under combined-slip conditions based on the UniTire model
by Xiaoyu Li, Nan Xu, Konghui Guo, Chao Yang, Yanjun Huang
Abstract: The UniTire model is a nonlinear semi-empirical tyre model for the dynamic simulation and control of a vehicle under complex wheel motion inputs involving pure longitudinal/lateral slip and combined slip. Based on the model, this study reveals how the inflation pressure affects the tyre forces under combined-slip conditions and then integrates such effects into the UniTire model to extend its applicability. First, by introducing a direction factor for the resultant shear force, the UniTire model for combined-slip conditions is developed to represent the tyre forces. Second, this paper comprehensively studies the effect of the pressure on the direction factor and tyre normalised properties to uncover the intrinsic correlation between the pressure and tyre forces. The experimental data are used during the entire analysis, and the results show that the anisotropy of tyre stiffness is a key factor for determining the resultant force direction under combined-slip conditions. More importantly, the UniTire model can be extended or complemented by incorporating the effect of the inflation pressure such that the model can be effectively applied in broader working conditions.
Keywords: UniTire model; combined-slip forces; tyre anisotropic stiffness; inflation pressure variation.
Design and evaluation of a driver intent based mobile control interface for ground vehicles
by Chengshi Wang, Kim Alexander, Philip Pidgeon, John Wagner
Abstract: The advent of drive-by-wire technologies has enabled exceptional mobility options for a greater number of drivers (e.g., age, experience, physical limitations). To extend the capability of current advanced drive-by-wire vehicles, an alternative vehicle driving mechanism must be considered to accomplish different driving manoeuvres while adapting to specific needs and constraints of certain drivers. In this study, a cellphone-inspired portable human-machine-interface (HMI) that incorporated the directional control of the vehicle as well as the brake and throttle functionality into a single holistic device is presented. A nonlinear adaptive control technique and an optimal control approach based on driver intent are also proposed to accompany the mechatronic system for combined longitudinal and lateral vehicle guidance. Assisting the disabled drivers by excluding extensive arm and leg movements ergonomically, the device has been tested in a driving simulator platform. Human test subjects evaluated the mechatronic system with various control configurations through obstacle avoidance and city road driving test, and a conventional set of steering wheel and pedals were also used for comparison. Subjective and objective results from the tests demonstrate that the mobile driving interface with the proposed control scheme can enhance the drivers performance by up to 55.8% when compared with the traditional driving system during aggressive manoeuvres. The systems superior performance during certain vehicle manoeuvres and approval received from the participants implies its potential as an alternative driving adaptation for disabled drivers.
Keywords: longitudinal and lateral dynamics; vehicle dynamics; nonlinear control; adaptive control; optimal control; state flow control; mobile control interface; portable HMI; emulated cellphone driving device; driver intent; human subject testing; ground vehicles; drive-by-wire.
Charge equalisation of electric vehicle battery system using intelligent controller
by Ginu Ann George, Mary Chacko Fossy, A. Prince, M.V. Jayan, Sunil P.R. Kumar
Abstract: Emissions from conventional vehicles adversely affect the environmental balance, thereby an enhanced adaptation of electric vehicles (EVs) is required. Among the existing energy storage systems, rechargeable batteries, especially Li-ion batteries, play a major role in the commercialisation of EVs owing to their long cycle life, high energy and power density and low self-discharge. A novel state of charge (SOC) based modular cell balancing equaliser (CBE) scheme integrated with intelligent control techniques is proposed. The performance of CBE is analysed, based on the simulation works done under a Simulink MATLAB environment with series-connected modular Li-ion battery. The bidirectional non-dissipative CBE structure cooperating with an intelligent controller balances the voltage among the cells considering the effect of the SOC of individual cells. The proposed balancing circuit and control method improves the speed of balancing and the accuracy without exceeding the upper voltage limit, as evident from the simulation results.
Keywords: electric vehicle; hybrid electric vehicle; energy storage system; lithium-ion battery; battery management system; cell-balancing equaliser; state of charge; fuzzy intelligent controller.
Gauge sensitivity methods for assessing and mitigating buckling effects present in vehicle structures
by Shengyong Zhang
Abstract: A prevalent methodology for improving fuel efficiency involves thickness reduction in sheet metal panels of a vehicles body. However, ramifications of thickness reduction are stiffness reductions, especially in the presences of bulking effects. It is imperative to accurately ascertain the effects of buckling on structural efficiency of any vehicle design. At a global level, gauge sensitivity evaluates the uniformity of stress distributions in a vehicle structure and provides profound insight to its structural efficiency. This paper revises the gauge sensitivity index to incorporate the presence of bulking effects on structural stiffness. It has been derived that onset of local buckling, as gauge reduction proceeds, will increase the stress non-uniformities and manifest as an increase in gauge sensitivity values. At a local level, gauge sensitivity distributions reveal the regions in a structure where local buckling is present. Case studies in this paper demonstrate the applications of local gauge sensitivity distributions in identifying good regions for stiffening to mitigate buckling effect and optimise vehicle structures relative to weight and stiffness.
Keywords: gauge sensitivity methods; buckling effects; vehicle structures; weight reduction; thin-walled structures; structural stiffness.
Structure design and anti-slip control system of magnetorheological limited slip differential
by Peng Zhao, Wanli Song, Zhongyang Diao, Menghao Liu, Na Wang
Abstract: This paper presents a novel design scheme of magnetorheological limited slip differential and analyses its structure and principle. Compared with the ordinary differential, the proposed magnetorheological limited slip differential overcomes the disadvantage of 'same torque but different speed' of the common differential. The finite element analysis is used to analyse and optimise the damping model. The anti-slip control system of the vehicle model is established based on the fuzzy PID method, and the performance of magnetorheological limited slip differential is studied by using simulation software to simulate the vehicles movement in typical road conditions. The simulation results show that the new magnetorheological limited slip differential proposed in this paper can redistribute the driving torque of the left and right driving wheels reasonably when the vehicle is skidding, so that the vehicle can overcome skidding and improve the stability of the vehicle.
Keywords: structure design; magnetorheological limited slip differential; finite element analysis; anti-slip control system; driving torque.
Rollover stability and anti-roll control of sport utility vehicle with driver in the loop
by Zhilin Jin, Zhenghua Yan, Wanzhong Zhao
Abstract: Rollovers are a type of fatal traffic accident for ground vehicles. Most rollover accidents, however, can be avoided through proper driver actions. In order to explore the effect of the drivers actions, the rollover stability of a sport utility vehicle (SUV) with a driver in the loop is analysed, and an anti-roll control strategy is proposed to prevent the vehicle rolling over when drivers cannot take proper emergency measures. To obtain the drivers reaction to vehicle rollover, the linear quadratic regulator method is applied to the drivers decision-making model. The laws of rollover stability and the corresponding influence of the parameters of the driver are illustrated. Then, a rollover prevention strategy using sliding mode control and an electronic hydraulic braking system is put forward to help the driver to control the vehicle. Furthermore, numerical simulations are presented for a SUV in tripped and untripped rollover conditions. The results show that experienced and physically fit drivers can manipulate the steering wheel accurately and timely to prevent vehicle rollover under emergency conditions. The proposed control method is helpful to improve roll stability and reduce vehicle rollover.
Keywords: rollover stability; driver in the loop; anti-roll control; electro hydraulic brake.
Analysis of consumer preferences regarding automated driving technology and driving environment: the case of South Korea
by Seungryong Jeon, Kyuho Maeng, Youngsang Cho
Abstract: This study analysed consumers preferences regarding the technological attributes of automated vehicle (AV) and the driving environment. We conducted a conjoint survey among 1008 respondents in Korea. Based on the collected data, a utility function was estimated using a mixed logit model, considering the heterogeneity of the respondents preferences. In the conjoint survey design, we considered six core technological and economic attributes of automated driving: road conditions, weather conditions, ambient lighting conditions, fuel efficiency, automated driving level, and price. The empirical results show high heterogeneity in consumers attitudes towards AV technologies. By comparing the relative importance of these six attributes, we found that the price of the automated driving option is the most important attribute, followed by road conditions. Furthermore, the predicted market share of AVs, considering their technological evolution, shows that affordable price is an important factor for their diffusion.
Keywords: automated vehicles; consumer preference; conjoint analysis; mixed logit; willingness to pay.
Optimal design and experimental research on a new hybrid electromagnetic actuator with energy reduction for vehicle suspension systems
by Renkai Ding, Ruochen Wang, Xiangpeng Meng, Long Chen
Abstract: The linear electromagnetic actuator (LEMA) fails to balance the energy regeneration/electric energy reduction and dynamic performance of suspension systems. A new hybrid electromagnetic actuator (HEMA) integrating a linear motor and a hydraulic damper is put forward and designed to address the problem in this study. On the basis of the preliminary determination of the design and constraints of the HEMA, a modified skyhook control is employed as the control method, and the performance parameters are optimised for different road conditions. The urban road condition is used as an example, the performance requirement that should be achieved in this driving condition is considered as the optimisation goal of the structural parameters, and the theoretically achievable performance of HEMA is obtained. Then, a prototype is developed for characteristic and dynamic control tests. Results show that the HEMA can ensure the dynamic performances while recovering vibration energy compared with the LEMA. In the active control process, the former can significantly reduce the electric energy consumption and achieve the same dynamic performance control. Moreover, the HEMA can significantly improve riding comfort while keeping the dynamic tyre load within a reasonable range. The results demonstrate that the HEMA can effectively coordinate the vibration energy regeneration/electric energy reduction and dynamic performance of suspension systems.
Keywords: HEMA; vibration energy regeneration/electric energy reduction; dynamic performance; optimal design; experimental research.
Experimental verification of the new methodology for assessment of the relative adhesion
by Milan Klapka, Ivan Maz?rek, Petr Novák
Abstract: The vehicle suspension in good technical condition is essential for safe driving. This article deals with experimental verification of new assessment methods for the resonance adhesion testing of the car suspension. Results of tests of more than 400 unique passenger cars assessed according to established EUSAMA methodology are compared with the results obtained by a suggested new methodology called standardised adhesion (STA). Additionally, the effect of excitation stroke amplitude is analysed experimentally on the assessed relative adhesion. The established EUSAMA methodology rather examines suspension in terms of handling the car under prescribed test conditions; however, the required testing conditions are outdated for current designs of suspension. The suggested STA methodology examines only a real condition of suspension damping under standardised testing conditions, which is its main advantage. The obtained results proved that the suggested STA methodology could be either a supplement or complete replacement of the established methodology for assessment of the suspension technical condition according to EUSAMA prescription which is not completely reliable currently.
Keywords: relative adhesion; suspension; shock absorber; EUSAMA; technical diagnostics.
Research on situation cognition approach of an unmanned surface vehicle under complex ocean conditions
by Lili Yin, Rubo Zhang, Hengwen Gu, Ning Guan
Abstract: This research project is conducted under the background of complex tasks of an unmanned surface vehicle in a complex ocean environment, to solve some problems such as assisting cognition for users, assessing the operation of users using situation cognitive results, and supporting the decision. The system framework of the situation cognitive approach is proposed in the paper, which includes environmental event recognition, influence degree of uncertain events calculation, executive capability assessment, task recommendation and comprehensive situation cognition. The cognitive approach for uncertain environment based on the combination of fuzzy logic and Bayesian network is proposed to achieve the cognitive process. The results of the situation cognitive method were used to update the situation ontology mode featuring probabilistic extension. In this way, the situation cognitive method for an AUV in an uncertain ocean environment extended the ability of uncertainty presentation and reasoning in ontology. The approach was validated by marine experiments and simulating experiments for the unmanned surface vehicle. Results show the effectiveness of situation cognitive approach.
Keywords: unmanned surface vehicle; complex ocean conditions; situation cognition; ontology model; marine experiments.
Research on intervention criterion and stability coordinated control of AFS and DYC
by Xiaojian Wu, Bing Zhou, Tingyang Wu, Qianxi Pan
Abstract: Aiming at improving vehicle handling stability, an intervention criterion and a coordinated control method for active front steering (AFS) and direct yaw moment control (DYC) are proposed in this paper. First, by analysing the characteristics of the linear, nonlinear and saturation regions of the lateral tyre force, the intervention criterion of AFS/DYC stability control based on the working state of lateral tyre force is proposed. Next, a 7-DOF (degree-of-freedom) dynamics model is established, and a method for identifying nonlinear pure lateral force model based on the onboard sensors and the vehicle handling stability experiment is developed. According to the identified tyre model, the mapping relationship between the lateral tyre force saturation point and wheel angle is constructed, which forms the rapid judgment method of the working state of the lateral tyre force, together with the approach of judging the linear/nonlinear state through the wheel angle. Then, a UKF-based state observer is designed to provide real-time information for the control system. The ideal reference, the upper level control algorithm of superimposed yaw rate, the lower level control algorithm, and the AFS/DYC yaw moment distribution coefficient reflecting the working state of the lateral tyre force are designed for the proposed AFS/DYC control system. Finally, a fishhook test and a step input test are carried out on low adhesion coefficient roads, which verifies that the proposed AFS/DYC coordinated control system can effectively improve vehicle handling and stability.
Keywords: vehicle handling stability control; active front steering; direct yaw moment control; intervention criterion; coordinated control; state observation.
A theoretical and experimental study on a vehicle with exhaust heat recovery
by Zhu Liang, Wang Shuangfeng, Chen Kai, Zeng Zhixin
Abstract: The performance of the Exhaust Heat Recovery System (EHRS) is analysed. First, an integrated vehicle model with the cabin heating system is established. A vehicle test is conducted to verify the simulation model and to assess the performance of original system. Using the simulation model, the interaction between the EHRS, cooling system, cabin heating system and exhaust system is studied. Then the cooling system is improved aiming to reduce the fuel consumption and improve the system performance. The numerical results show that increasing the pump speed ratio can significantly improve the performance of low-temperature heating, and has little effect on fuel consumption. Adjusting the cooling circuit of the EHRS can effectively reduce fuel consumption and improve heating performance.
Keywords: integrated vehicle system model; exhaust heat recovery; cooling system; cabin heating system; exhaust system.
Study on reducing cogging torque and core loss of in-wheel motor for electric vehicle based on stator full-slot offset
by Qiping Chen, Xuanjun Huang, Hao Shao, Hui Chen, Chagen Luo
Abstract: In order to reduce cogging torque and core loss of in-wheel motor for electric vehicle, the paper proposes a full-slot offset method to analyse the above problems. Firstly, the calculation formulas of cogging torque and the core loss are deduced, the parameters of the in-wheel motor are determined, and the geometric model of the in-wheel motor is established. Secondly, the models with different offset angles are imported into the finite element simulation model, the cogging torque and core loss are calculated respectively, and the correctness of the model is verified. The simulation results show that the full-slot offset angle is 3 degrees, and the cogging torque and core loss of the in-wheel motor can be optimized. The reduction of cogging torque is about 98%, the reduction of core loss is about 65%, and the reduction of the first harmonic is about 96%, and the conformity of the theoretical analysis results with the final simulation results shows that three-dimensional finite element method. It can be seen that the full-slot offset method can obviously restrain the cogging torque, core loss and the first harmonic. Therefore, the full-slot offset method proposed in this paper provides a certain reference value for the optimization design of cogging torque and core loss of in-wheel motor for electric vehicle.
Keywords: electric vehicle; in-wheel motor; full-slot offset; cogging torque; core loss.
Power distribution methods of ultra-capacitor/battery hybrid power source for vehicular applications
by Benxiang Lin, Guizhou Ren
Abstract: Compared with traditional single power sources such as batteries, hybrid power source (HPS) for vehicular applications can reduce energy consumption and improve energy efficiency. The development of high-efficiency HPS for electric vehicle (EV) faces a huge challenge to meet the elevated energy demands under complex and variable working conditions. A HPS consisting of ultra-capacitor (UC) with high power density and battery with high energy density is recognized as having strong potential to meet this challenge. Reasonable power distribution control and optimization methods can significantly improve the working efficiency and application performance of UC/battery HPS. However, various control methods have different performance characteristics. It is not possible to claim that any one of them is the most effective method, usually making it difficult to quickly and accurately determine the most suitable control method for a specific application of UC/battery HPS. This paper aims to provide a comprehensive and transparent description of the known power distribution control methods that recently applied in various UC/battery HPSs. The article starts with an overview of typical energy storage technologies for HPS. After that, the power distribution control methods of UC/battery HPS are analysed and discussed systematically, such as explicit rule-based, fuzzy rule-based, model prediction, dynamic programming (DP), convex optimization, particle swarm optimization (PSO), and genetic algorithm (GA). Following this, a new UC/battery HPS is proposed, its operation principle is described, rule-based and fuzzy-based power distribution methods are initially formulated. The results of a simulation example verify the validity of the designed scheme.
Keywords: ultra-capacitor/battery; hybrid power source; electric vehicle; power distribution method.
Technology development strategies for electric vertical take-off and landing: focusing on the case of South Korea
by Yeon Jae Choi, Hyun Jin Cho, Ye Yun Kwun, Sanghak Lee
Abstract: Electric vertical take-off and landing (eVTOL) constitutes a promising type of personal air vehicle (PAV). More research pertaining to the detailed specifications for eVTOL configurations is therefore required. This research addresses the urgent need for eVTOL technology development strategies aimed at vitalising eVTOL aircraft commercialisation in South Korea. It does so by evaluating the relative importance and readiness level of technology using the analytic hierarchy process (AHP) and technology readiness level (TRL) analysis, respectively. Expert surveys are conducted based on a previously identified eVTOL technology tree. The ratings are then presented on a four-quadrant importance-performance analysis (IPA) matrix where each eVTOL technology is plotted according to its perceived relative importance and readiness level. The main categories of controlled autonomous flight and propulsion fall into Quadrant II (high importance and low readiness level), indicating that they constitute the highest priority among categories, and that a fast-follower strategy via the establishment of strategic partnerships should be pursued.
Keywords: electric vertical take-off and landing; personal air vehicle; analytic hierarchy process; technology readiness level; importance-performance analysis; South Korea.
Multi-objective optimiation of the passenger car seat frame using grey relational analysis and grey entropy measurement
by Zhiying Shan, Wei Wang, Jiangqi Long
Abstract: At present, more attention has been paid to the performance and lightweight design for passenger car seats. The optimisation design for seat frame is performed in this research. The innovation for this research is that a particular method of lightweight optimization is proposed according to the characteristics of seat frame. The best thickness-material scheme of the parts that needs to be optimised (opti-parts) is obtained by applying the method of grey relational analysis, grey entropy measurement, and average strain indices (GRA&GEM(ASI)). In addition, in order to verify the advantages of GRA&GEM(ASI), a comparison is made among serval different techniques. The results show that, not only the gross cost and gross mass of opti-parts are reduced by ?3.13 (16.68%) and 0.67kg (16.88%), respectively, but also the performance and reliability of seat frame is well guaranteed. The method of GRA&GEM(ASI) proposed in this work makes significant contributions effectively performed in multi-objective optimisation design for passenger car seat frames.
Keywords: seat frame of passenger car; multi-objective optimisation; grey entropy measurement; grey relational analysis.
Unique approaches to integrating semi-active suspension and active anti-roll bar control systems
by Sergio Guillen, Francis Assadian
Abstract: Automated control systems are commonly applied to road vehicles to improve certain dynamic behaviour. Active roll control systems are known to significantly improve roll dynamics (Zhu and Beshah, 2014). Additionally, there are a multitude of actuation mechanisms which can accomplish this, and each with unique benefits (Buma et al 2010; Mohan et al, 2012). Recent developments in the literature show successful control integration strategies, where one or more actuators are coordinated to achieve the same control objective(s). Improvements on dynamics behaviour and safety (distribution of actuator demands) are some of the benefits of integrating standalone control actuators (Assadian and Edo, 2006; Her et al., 2013). In this paper, the frequency domain, model-based control design method known as Youla parameterisation is applied to road vehicle models equipped with an active anti-roll bar and continuously controlled suspension dampers (CDC). Using this methodology, this paper demonstrates two novel strategies for integrating CDC with Active Anti-Roll Bar (AARB) which accomplish steady-state roll angle reference tracking while improving transient roll motion.
Keywords: Youla parameterisation; integrated control; continuous damping control; active roll control.
Fully hydraulic synchronous steering control of a vehicle based on gain fuzzy sliding mode variable structure
by Guang Xia, Jianshan Chen, Xiwen Tang, Linfeng Zhao, Shaojie Wang
Abstract: Aiming at the problem that the expected steering curve determined by the existing methods has poor traceability and cannot achieve synchronous steering, a method for determining the expected steering curve and its feasible area is proposed. Aiming at the uncertainty of system disturbance and the nonlinearity of oil leakage, based on the combined reaching law, sliding mode control is adopted, and the saturation function is introduced instead of the sign function, which imposes certain constraints on the control system. Aiming at the problem that the combined approximation law lacks gain adaptation, a fuzzy rule table based on wheel angle and angular velocity is formulated, and the gain fuzzy sliding mode control is realised. Simulation and experimental results show that the expected steering curve based on steering efficiency has good tracking performance; the gain fuzzy sliding mode variable structure control has excellent dynamic response characteristics and control precision. It can effectively eliminate steering deviation and realise full hydraulic synchronous steering of steering system.
Keywords: full hydraulic steering system; synchronous steering; fuzzy sliding mode control; expected turning curve; steering deviation.
Experimental performance comparison of R1234yf and R134a automobile air conditioning systems employing a variable capacity compressor
by Erkutay Tasdemirci, Ertan Alptekin, Murat Hosoz
Abstract: The use of refrigerants from the hydrofluorocarbon family has been restricted owing to their high global warming potential, and the manufacturers have been using R1234yf recently, a refrigerant from the hydrofluoroolefin family, as a substitute for R134a in mobile air conditioning (MAC) systems. In this study, a laboratory MAC system with a variable-capacity compressor was set up, and its comparative energetic and exergetic performance was evaluated for the cases of using R1234yf and R134a by changing the test conditions in a wide range. The results revealed that the system with R1234yf provided on average 13.7% less cooling duty and 12.8% less coefficient of performance based on the total power input relative to the system with R134a. Furthermore, the system with R1234yf destructed on average 18.9% more exergy per unit cooling duty. Excluding the condenser, the components of the R1234yf system destructed more exergy per unit cooling duty than those of the R134a one.
Keywords: R1234yf; R134a; exergy; automobile; air conditioning; variable-capacity compressor.
Multi-objective optimisation of composite coil spring for vehicle suspensions
by Xiaokai Chen, Chao Li
Abstract: This work presented a general form of spring rate and strength prediction model and an optimisation method for developing a suspension FRP coil spring. The prediction model can deal with an arbitrary sequence of layers instead of widely used
Keywords: fire-reinforced plastic; coil spring; stiffness prediction model; strength prediction model; optimisation design.
Coupled electrothermal model and thermal Fault diagnosis method for lithium-ion battery
by Qiuting Wang, Wei Qi
Abstract: The dynamic behaviour of the lithium-ion battery system is analysed. The nonlinear parameters, residual errors and thermal faults of the battery model are studied. In our study, a coupled electrothermal model is established based on the cell electrical dynamic characteristics. The parameter identification algorithm is presented based on Lyapunov observer. The core temperature and surface temperature of the battery cell are calculated based on extended Kalman filter. We propose a new thermal fault diagnosis method and the residual generation scheme. The UDDS (Urban Dynamometer Driving Schedule) dynamic working condition is used to verify our electrothermal model and fault diagnosis method. The experimental results indicate that the thermal characteristics can be described and the thermal fault can be diagnosed more accurately.
Keywords: lithium-ion battery; coupled electrothermal model; fault diagnosis; Lyapunov observer; extended Kalman filter; UDDS.
The optimisation design of CFRP bumper beam based on ply compatibility
by Jing Chen, Sen Xu, Zhen Liu, Aotian Tang
Abstract: This study aimed to develop an optimization approach for carbon fibre-reinforced polymer bumper beams. First, we established a specific finite element model and conducted a high-speed crash simulation of a steel bumper beam to verify the accuracy of the model. Then, the shape and parameter of the section of the bumper beam were determined using an orthogonal experimental design, and the concept of ply compatibility constraint was proposed. Subsequently, the ply sequence and thickness were optimised using the multi-island genetic algorithm and the multi-objective particle swarm optimisation algorithm based on kriging surrogate model with adding-point strategy. Results showed that the section force of the energy-absorbing box of the bumper beam was reduced after optimisation. The indexes of intrusion and energy absorption were also improved to some extent compared with the original ones. A real vehicle experiment proved that the optimised bumper system met all the requirements on strength and crashworthiness, with 47.61% weight reduction.
Keywords: bumper beam; carbon fibre reinforced polymer; ply compatibility; multi-island genetic algorithm; KMOPSO; kriging surrogate model.
Investigation of drivetrain dynamics on low-
by Jianing Yang, Georg Jacobs, Achim Kramer
Abstract: This article aims to investigate the influence of the low-friction ground on off-highway drivetrain dynamics. A comprehensive vehicle simulation model is established for this purpose. This vehicle model consists of three parts: the torsional drivetrain model, the vehicle body model of longitudinal dynamics and the tyre model with slip behaviour. To correctly reflect tyre slip behaviour, the brush model, which features a physical description of the tyreground contact patch, is applied. A group of simulations is carried out on the complete vehicle model, mainly from two perspectives: drivetrain eigen-modes and drivetrain transient response. For the drivetrain eigen-mode analysis, different tyre slip states and the transition process between these two states are taken into consideration. For the drivetrain transient response, the vehicle is assumed to drive over a patch of low-
Keywords: low-µ ground; tyre slip model; brush model; torsional drivetrain model; drivetrain eigen-modes; drivetrain transient response.
Design and analysis of the dual motor coupling drive system for electric vehicle
by Qiping Chen, Zhiyi Zheng, He Wang, Yiming Hu, Zhihui Xu, Jianqun Zhang
Abstract: In order to improve the efficiency of the drive system of electric vehicle, the main and auxiliary motors of the dual motor coupling drive system of electric vehicle are designed in this paper. Finite element analysis of the designed motor model was carried out by Maxwell 2D module, by analysing the operation performance of the two motors in the steady and transient fields, the changes of magnetic line, flux density distribution, electromagnetic torque and other parameters when the motor is working are obtained. The calculation results are basically consistent with the simulation results. The results show that the maximum output power of the main and auxiliary motors is 100 kW and 60 kW, respectively, and the maximum efficiency is 95.7% and 96.9% respectively. the parameters of the two drive motors designed are reasonable and the performance meets the expected requirements.
Keywords: electric vehicle; dual motor drive; electric drive; coupling drive system; electromagnetic design.
Special Issue on: Multi-Objective Design and Structural Optimisation of Vehicle Components with Nature-Inspired Optimisation Algorithms
Integrated optimisation of two-speed powertrain parameters and shifting strategy for energy in electric vehicle
by Daoguang Zhu, Congbo Li, Lingling Li, Ying Tang
Abstract: In order to improve the economic performance and extend the range of electric vehicles (EV), an integrated optimisation method for the design and optimisation for powertrain parameters and shifting strategy are proposed. Firstly, the powertrain parameters are matched to ensure the dynamic performance of electric vehicles and the shifting strategy with comprehensive performance is designed based on the analysis of dynamic and economy performances. Secondly, a multi-objective integration model of powertrain parameter and shifting strategy optimisation is proposed to take the minimum energy consumption as the optimisation objective without sacrificing dynamic performance, which is solved by a multi-objective particle swarm optimisation algorithm. Finally, to verify the energy-saving performance of the proposed multi-objective integration problem, case studies have been conducted and a whole vehicle simulation model is proposed based on Matlab/Simulink platform. The simulation results show that the proposed method can effectively reduce the energy consumption and extend the range of electric vehicles under different driving cycle.
Keywords: electric vehicle; powertrain parameter; shifting strategy; multi-objective integrated optimisation; particle swarm optimisation algorithm.
Special Issue on: New Energy Vehicles' NVH and Lightweight and Control Technologies
A clustering-based simplification of massive automobile-bodies point cloud for lightweight design
by Yu Zhou, Yue Song, Qi Zhang, Yan Wang, Farong Du, Shuiting Ding
Abstract: Adaptive simplification for massive and large-scale automobile-bodies point cloud obtained by 3D laser-scanning has proven to be an effective technology to conduct lightweight design. This paper introduces a point-based algorithm to simplify laser-scanning point cloud without any support of fitted surface. The intrinsic characteristic of laser-scanning data is investigated to produce a topological connectivity for adjacent points in scan-lines. We explore an automatic normal-vector estimation framework through the relationship between normal-vector and its adjacent geometric elements. To retain more points in high-curvature areas and fewer points in planar regions efficiently, the local normal-vector variance is adopted to determine subdivision-decision condition. The boundary points are detected and then preserved before non-uniform subdivision. A relevant simplification system based on our algorithm is developed. Many simplification cases are implemented to validate the effectiveness of our method and demonstrate the feasibility for automobile-bodies point cloud. The comparison with other point-based methods is also performed to illustrate the superiority of our method.
Keywords: point cloud; simplification; laser scanning; lightweight design; automobile body; hierarchical clustering; reverse engineering.
A mathematical model for vibration analysis of a parallel hybrid electric bus powertrain
by Wei Chen, Zhengwei Li, Yulong Lei, Sajad Saraygord Afshari, Yao Fu, Liguo Hou
Abstract: This paper presents a parallel hybrid electric bus equipped with an automated manual transmission (AMT) and a mathematical model of the hybrid powertrain is developed for vibration analysis. The powertrain dynamic model is established by a modular modelling approach. A detailed AMT dynamic model, considering gear time-varying meshing stiffness, shaft elastic deformation, and bearing elastic support, is incorporated into the powertrain dynamic model. The damping and gyroscopic effects of the gear-rotor in the AMT are considered as well. The AMT dynamic model is validated by experimental data from the time and frequency domain comparisons. Finally, the parameter analysis of the dual-mass flywheel (DMF) is used to illustrate how to use the proposed powertrain dynamic model for vibration reduction. The influence of the DMF parameters on vibration responses of the system with varying engine rotation speed is investigated. This study provides a basis for further vibration control of the hybrid powertrain during the engine driving mode.
Keywords: hybrid electric bus; powertrain; dynamic modelling; vibration analysis; dual-mass flywheel.
Investigation on energy consumption of electric vehicle with micro gas turbine as a range-extender under various driving cycles
by Xiangbo Zhang, Fenzhu Ji, Farong Du, Shuiting Ding, Yu Zhou
Abstract: The Micro Gas Turbine (MGT) offers an attractive option for range-extended electric vehicles (REEVs) to prolong the driving range. This research aims to investigate the energy consumption of MGT-based REEV under different driving cycles to evaluate the performance of the MGT-based range extender. As a core component, the performance of MGT with recuperator is analysed and simulated based on Brayton cycle. The steady-state and transient characteristics of the MGT model is verified through experiments. A model of the MGT-based REEV is established to access the energy consumption of EV under highway fuel economy cycle (HWY) and supplementary FTP driving cycle (US06). Results show that the MGT model has a high precision. The difference between simulation and experiment is smaller than 2% in power, and
Keywords: range-extended electric vehicle; micro gas turbine; energy consumption; driving cycles; simulation.
Lightweight design of a bodyinwhite structure using a hybrid optimisation approach
by Dengfeng Wang, Shenhua Li
Abstract: To achieve lightweight structure for a BIW (bodyinwhite), this study proposes a hybrid optimisation approach that integrates the subspace division of a BIW structure, relative sensitivity analysis, correlation analysis, NSGAII (nondominated sorting genetic algorithm II) combined with a RSM surrogate model, and design of experiments combined with ETOPSIS (entropy weighttechnique for ordering preferences by similarity to ideal solution). The approach improves the optimisation efficiency and solves the problem of nonlinear crashworthiness optimisation. The decoupling of the linear basic performance and nonlinear collision safety performance of a BIW are achieved. According to the type of performance response, design variables are screened, and three subspace structures of the BIW are optimised. Optimisation results indicate that the mass of the BIW structure is reduced by 17.0 kg. The performance quotas of the BIW are within the specified design baseline range. Therefore, the proposed approach can be effectively applied to the lightweight design of a BIW structure.
Keywords: BIW; body–in–white; lightweight design; crashworthiness optimisation; relative sensitivity analysis; correlation analysis; NSGA–II; design of experiments; TOPSIS.
Research on vehicle window buffeting mechanism and noise control
by Qiliang Wang, Xin Chen, Yingchao Zhang, Qingqing Guan, Mingyang Song
Abstract: For a moving car, buffeting noise is generated when a window is opened alone, which seriously affects the comfort of passengers. In particular, there is still no effective control method for side window buffeting, so it is very important to study the buffeting mechanism and characteristics for noise control. First, this paper analyses the pressure change law during the shear vortex shedding process through simulation, and explores the Helmholtz resonance characteristics of the passenger cabin, so as to reveal the causes of the buffeting phenomenon. Secondly, wind tunnel tests are used to study the effects on buffeting of vehicle speed, window opening size and other factors, and the differences in buffeting characteristics between sunroof and side windows are compared, then the reasons for buffeting changes are analysed through simulation. Finally, the passive control and active control are discussed, which have reference significance for the control of vehicle window buffeting.
Keywords: vehicle window buffeting; flow mechanism; buffeting characteristics; noise control.
Multi-objective optimisation of automobile sound package with non-smooth surface based on grey theory and particle swarm optimisation
by Shuming Chen, Zhenyu Zhou, Jixiu Zhang
Abstract: This paper studies a multi-objective optimisation design of the sound package with non-smooth surface, for enhancing the acoustic performance and reducing the material weight. In order to perform the acoustic simulation of the sound package with non-smooth surface, an effective finite element analysis procedure was used in this work. The sound absorption performances of porous materials were predicted by using two-microphone transfer function method combined with finite element method (FEM). Smooth surface and triangular surface were chosen for analysis to compare sound absorption performances of sound packages. Moreover, an orthogonal experiment was designed to compare sound absorption performance and material mass among different sound package with different surface parameters and thickness. Thus, the multi-objective design was converted into a single objective with grey correlation degree. Furthermore, the average grey correlation degree of parameter variables was analysed. On this basis, the optimal combination was selected by using particle swarm optimisation algorithm. From the optimization data, triangular surface sound package material with the optimal surface parameters and thickness was numerically simulated applying finite element method. The simulation result shows that sound absorption performance was improved while the material mass decreased.
Keywords: sound absorption coefficient; optimisation; sound package; grey relational analysis.
Unified AHP-TOPSIS and DEA technique for the adoption and performance evaluation of green transportation alternatives in India
by Neha Gupta, Chand P. Saini, Amit Dangi, Tanwir Akhtar
Abstract: We cannot think of todays age without transportation. Also, global warming, environmental degradation, adverse health implications, and greenhouse gas emission are some of the problems in the existing transportation mode. The solution to these problems is the shift towards green transportation, which means shifting to such transportation practices or vehicles that do not have any negative impact on the immediate environment and are eco-friendly. Therefore, the use of electric vehicles (EVs) can shift India towards sustainable transportation or eco-friendly transportation. EVs are different from petrol vehicles on distinct properties. EVs have zero tail-pipe outflows, less noise, and low running expense contrasted with the internal combustion engines. This paper adds to the existing information by undertaking a multicriteria analysis for ranking and performance measures of EVs based on the rating by two stakeholder groups, electric vehicle dealers and electric vehicle users. In this paper, the criteria for the selection of EVs are identified from the literature and personal interviews. This paper uses the combination of AHP, TOPSIS, and DEA techniques to rank the various types of EV and measure the performance of eight electric and eight hybrid electric cars that exist in India.
Keywords: green transportation; electric vehicles; multicriteria analysis; AHP; TOPSIS; DEA.
Multi-disciplinary design optimisation considered fluid-structure interaction and life prediction applied in the lightweight carbody structure
by Bingrong Miao, Yaoxiang Luo, Qiming Peng, Chuanying Jiang, Zhongkun Yang
Abstract: Multi-disciplinary design optimisation based on rigid-flexible multi-body system is presented to solve the multi-object design optimisation problems of lightweight carbody structures by considering the fluid-structure interactions at different typical load cases. A mathematical model is developed to simulate structure interactions based on the theory of finite elements. The model is integrated with a multi-object optimisation approach that uses the non-sort genetic algorithm method. The multi-body system was used to understand complex vehicle system dynamics performance and obtain the structure load time histories. Through performing structural quasi-static stress analysis method, the structure dynamic stress/strain histories were obtained for fatigue life evaluation. The results demonstrate the effectiveness of the proposed approach in simultaneously considering the structural vibration and the aerodynamic pressure at several vehicle speeds by proper lightweight design. This method has the advantage that it can be used to understand the interaction mechanism between the vehicle dynamics characteristics and lightweight structural fatigue damage.
Keywords: multi-disciplinary design optimisation; multi-body system; lightweight design; finite element method; railway.
Establishment of mathematical model of inner tooth profile curve and simulation based on dual phase silent chain
by Yabing Cheng, Xiaomin Chen, Yang Li, Xinyue Li, Luxiang Chen, Jiaxing Niu
Abstract: According to the meshing principle of chain drive, the formula of coordination transform and pitch variation principle of dual phase Hy-Vo silent chain, the formula of the inner tooth profile curve of dual phase Hy-Vo silent chain is built. The mathematical model of the inner tooth profile curve of the new chain plate is established. The dynamic model of quasi-conjugate meshing between the working chain plate of silent chain and the involute sprocket is established. The new type silent chain system with inner tooth profile is compared with the previous one. The simulation results show that the new type Hy-Vo silent chain system has less fluctuation, less change of angle velocity of chain plate and moves more smoothly. The rationale of the mathematical model and the superiority of the dynamic model of the new type Hy-Vo silent chain system with inner tooth profile are verified.
Keywords: chain transmission; dual phase Hy-Vo silent chain; inner tooth profile curve; fluctuation quantity; multi-variation.
Sound quality evaluation of pure electric vehicle with subjective and objective unified evaluation method
by Jing Cheng
Abstract: The focal points for sound quality of a pure electric vehicle (PEV) usually depend on its operating condition. Therefore, a subjective and objective unified evaluation model for sound quality evaluation of PEV based on operating condition is presented. With acoustic test results, a hierarchical comparison method (HCM) is proposed for their subjective acoustic quality evaluation. Four psychoacoustic parameters and one evaluation index of pure tonal noise are used to evaluate the noise samples. A noise sample library based on operating mode is established, and the sound quality evaluation models based on the back propagation neural network (BPNN) and the support vector machine (SVM) were established and compared. The results show that the evaluation model has high accuracy, and when the sample size is insufficient, the accuracy of SVM model is better than the BPNN model.
Keywords: PEV; sound quality; HCM; subjective and objective unified model; multiple operating conditions; BPNN; SVM.
Comparison of deep learning methods for predicting charging energy of power batteries
by Xuefeng Zhu, Guoliang Xie
Abstract: Accurate prediction of the electric vehicle charging energy is essential for power grid companies to rationally allocate power resources, customise appropriate tariffs and select the location of charging piles. Currently, machine learning methods have been widely applied in this field. Aiming to predict Electric Vehicles (EV) charging energy more precisely, this paper compares several machine learning methods and concludes that Long Short-Term Memory (LSTM) neural network has better behaviour. As the initial training data was incomplete, we supplemented the training data with MissFrorest neural network. We compared Back Propagation (BP), Xtreme Gradient Boosting (XGBoost), and LSTM networks for the prediction of charging energy, and found that LSTM has the best prediction effect, XGBoost has the second best, and BP has the worst effect. LSTM addresses the issue of gradient dispersion due to introducing time series, and thus has a better prediction effect. The experimental results show that Mean Absolute Error (MAE) and Root-mean-square error (RMSE) indices for four of five experimental vehicles using the LSTM algorithm are smaller than those using BP and XGBoost methods. Compared with the BP, XGBoost algorithms, the average reduction of MAE is 42.79%, 23.48%, and RMSE is reduced by 43.42%, 19.65%.
Keywords: predicting charging energy; deep learning; power batteries; electric vehicles.
Special Issue on: Cyber Security in Internet of Vehicles
Stabilisation of traffic flow by considering multiple information based on vehicle-to-vehicle communication
by Qian Li, Haiyang Wang, Dongfan Xie
Abstract: The rapid development of advanced technologies means that vehicles can share information with each other based on vehicle-to-vehicle (V2V) communication. It is expected that the V2V information can improve efficiency and stability of traffic flow, which has attracted much attention in traffic flow theory. To this end, this study develops an alternative car-following model with the consideration of V2V information. By using the linear stability theory, stability analysis is performed, and the string stability condition is obtained. The results indicate that V2V information can improve the stability of traffic flow, and traffic fluctuations can thus be suppressed. Case studies are carried out based on numerical simulations, and the results coincide with the theoretical ones.
Keywords: vehicle-to-vehicle; communication; car-following model; stability analysis; traffic congestion.
Research on service braking control strategy for heavy-duty truck on long downhill based on genetic algorithm
by Peilong Shi, Qiang Yu, Xuan Zhao, Pan Liu, Rong Huang
Abstract: While driving a heavy-duty truck on a long downhill road, the driver operates the pedal to brake depending mainly on driving experience and road condition. However, the drum temperature rises sharply when the service braking system works frequently. Hence, how to operate the brake pedal to avoid heat fading becomes an important issue. To solve this problem, a service braking control strategy for heavy-duty trucks based on genetic algorithm is proposed. In order to ascertain the main factor that causes the drum temperature to rise sharply, the constant speed control and the expected speed range braking control with different pedal forces strategies are simulated. It is found that several factors, including pedal force and speed range, have a significant effect on temperature, also the braking frequency and cumulative working time. Therefore, this paper proposes a multi-objective genetic optimisation algorithm on the braking control, adopting the constancy of braking efficiency, the degree of driver fatigue and driving safety as the objective function, optimising the brake pedal force, the desired speed range and average speed on long downhill roads. The results reveal that the multi-objective optimisation method based on genetic algorithm can slow down the rise in brake temperature, reducing the frequency of brake application and the driving intensity for the driver.
Keywords: heavy-duty truck; braking control; driving safety; optimisation method.
Special Issue on: The Modelling and Control of Automated Guided Vehicle Systems
Dynamic characteristics analysis of spatial suspension mechanisms based on instantaneous screws
by Guofeng Zhou, Yafei Wang, Zhisong Zhou, Jingkai Wu
Abstract: Multi-link, MacPherson and double-wishbone suspensions are commonly used in passenger cars. The dynamic characteristics of a vehicle are strongly affected by these independent suspensions. This paper presents a unified quarter-vehicle model which incorporates both the spatial suspension kinematics and the tyre dynamics for the dynamic analysis of the three spatial suspensions. In the quarter-vehicle model, it consists of a spatial suspension mechanism and a ground-wheel contact model. For a vehicle running straight ahead on the uneven road, the dynamic characteristics analysis using the quarter-vehicle model is divided into three steps. Firstly, for the quarter-vehicle model the corresponding instantaneous screws are determined at any instant. Then, the theory of screws is used to describe the kinestatics of the quarter-vehicle model. Finally, on basis of the kinestatic relations, the dynamic equations derived using the Lagrangian function are applied to the dynamic analysis. As to the feasibility of the theoretical method, different road disturbances are considered for the numerical examples. The simulation results respectively of the theoretical method and the widely used Adams/View software are compared to verify the numerical performances of the dynamic analysis.
Keywords: spatial suspension mechanisms; quarter-vehicle model; instantaneous screws; kinematics; statics; dynamics; theory of screws.
Parameter-space-based robust control of heterogeneous platoon with stochastic packet dropout
by Jiawei Wang, Fangwu Ma, Sheng Zhu, Yu Yang, Sukru Yaren Gelbal, Bilin Aksun-Guvenc, Levent Guvenc
Abstract: This paper presents a parameter-space-based multi-objective, robust CACC platooning controller for a heterogeneous vehicular platoon with stochastic packet dropout during inter-vehicular communication. The parameter space approach is adopted to optimise the gains of the robust controller, to handle the multiplicative uncertainty, and to project the robust performance requirements. The feasible region where internal stability and preceding vehicle following accuracy are satisfied is then visualised in the parameter space. Subsequently, the robust controller, which combines the feedforward loop and feedback loop, is developed by selecting the gain from the feasible solution area. The simulation results of a six-vehicle heterogeneous platoon are presented and evaluated to verify the efficiency of this control algorithm. The results show that string stability and comfort are well guaranteed by this robust controller, even for the heterogeneous platoon with stochastic packet dropout and the following error is limited to an acceptable range.
Keywords: cooperative adaptive cruise control; stochastic packet dropout; heterogeneous platoon; parameter space approach.
Active roll control for rollover prevention of semi-trailers with robust invariant set
by Echuan Yang, Chuanren Xie, Jian Ou, Senlin Zhang, Liang Qin
Abstract: To improve the roll stability of semi-trailers, a robust model predictive controller (RMPC) is designed. To analyse the vehicle dynamic behaviour, a nonlinear seven-degrees of freedom (7-DOF) vehicle model is defined. Based on the robust invariant set theory, and taking the uncertainty of the drivers driving behaviour into account, the maximal robust control invariant (RCI) set is calculated and its robustness is analysed. The N-step controllable sets of the vehicle are also solved. An anti-roll controller considering multiple constraints is designed based on the robust model predictive control theory. Simulation results show that the controller can keep the lateral load transfer rate within 0.7 and make the state variables converge. In addition, the controller can reduce the lateral acceleration by 50% in the step steering input test.
Keywords: anti-roll control; invariant set; robust control; model predictive control; semi-trailer.
Design of remote control smart car with two-way information communication
by Hongyan Qin, Ben Zhang
Abstract: This paper takes Freescale's remote wireless control smart car as the research object, completes the design of the main control board hardware circuit and the upper controller remote control software, and realises two-way information communication. The smart car collects the vehicle position signal by the CMOS image sensor, and transmits the image to the controller in real time by the APC220 wireless module. The XS128 microcontroller receives the control instructions sent by the controller, and drives the DC motor to control the smart car. The single-chip microcomputer collects the pulse signal of the wheel speed through the photoelectric encoder, which is captured by the MCU for PID closed-loop control. Tests show that the smart car and the controller can achieve error-free data transmission in a long-distance, multi-interference environment, and have good stability and obtain real-time control information.
Keywords: wireless remote control; smart car; two-way information communication; anti-jamming design.
Special Issue on: Vehicle Design Processes
The design and test of circular-cutting and middle-placing windrower for oilseed rape
by Haifeng Luo, Xiao Xiao, Beibei Zhang, Xu Li, Mingliang Wu, Chunyun Guan, Wei Xie
Abstract: An electric-drive circular-cutting and middle-placing windrower for oilseed rape is designed. Circular cutter adopts the cutting method that a chain-driven movable blade is combined with upper and lower double fixed blades, and designs a double-support circular cutter as well. Moreover, the symmetrical hugging and middle-placing reeling device is designed through artificial reeling operation. The simulated and kinematic analysis of the reeling device is done as well. The simulated analysis results show that the reeling track meets the operation requirement and the reeling devices have a good effect on the rape plants. The intelligent synchronous reeling control is designed on the reeling device drive. The field test of the prototype showed that the placing angle of the windrower was 11.48
Keywords: circular cutting; symmetrical pushing; intelligent synchronous control; oilseed rape; windrower.
Temperature and humidity optimisation control of cold chain vehicle carriage based on grey wolf algorithm
by Yulong Wan, Xinchun Li
Abstract: There are some problems in the traditional temperature and humidity control of cold chain transportation vehicles, such as poor control effect, poor real-time control, etc. The paper introduces Descartes coordinate system to construct the air motion tensor model in the carriage of cold chain transportation vehicles. The influence parameters of temperature and humidity of cold chain transport vehicles are divided into different temperature and humidity parameters. The grey wolf algorithm is used to search for the optimal solution of humidity influence parameters, and different wolf fitness models are constructed to determine the optimal solution of parameters to realise optimal control. The comparison shows that: the control deviation of temperature and humidity of cold chain transport vehicle compartment is always lower than 0.4, and the control efficiency coefficient is higher than 0.9.
Keywords: cold chain transport vehicle; compartment temperature and humidity; Gray Wolf algorithm; tensor model; temperature and humidity comprehensive parameters; comfort index.
Research on collaborative lane changing control method of unmanned vehicle based on internet of vehicles cooperation
by Haibo Zhang
Abstract: In this paper, a new method of coordinated lane change control for unmanned vehicles based on the cooperation of vehicle network is proposed. The paper analyses the vehicle lane change strategy, calculates the distance between the self vehicle and the front vehicle without collision and tail, and preliminarily plans the track of lane change according to the environmental information obtained from the visual environment perception part. With the support of the collaborative model control of the vehicle network, the Kalman predictor and SIFT feature extraction method are used to obtain the information of the motion and position of the unmanned vehicles, and realize the coordinated lane change control. The experimental results show that the error range of the operation failure rate is 1.00-2.31, the response time is 0.878 min, the vehicle lane change efficiency is high, and the practical application effect is good.
Keywords: internet of vehicles collaboration; unmanned driving; vehicle coordinated lane change; control.
Design of lane changing warning system for high speed vehicle based on fuzzy adaptive PID
by Xiaoguang An, Xiaofan Lu
Abstract: In order to overcome the low precision and efficiency of the traditional lane changing warning system for high-speed vehicles, a new lane changing warning system based on Fuzzy Adaptive PID is proposed in this paper. Firstly, the hardware structure of the control system is designed. The hardware mainly includes the early warning system control module and the fuzzy adaptive PID controller module to achieve high-precision early warning. In the software part of the system, in order to improve the turning sensitivity of the car, the fuzzy adaptive PID control algorithm is used for yaw rate feedback control, and the lane change warning algorithm is constructed. The experimental results show that, compared with the traditional lane changing early warning system, the early warning accuracy and efficiency of the designed system are significantly improved, and the maximum early warning accuracy reaches 96%.
Keywords: fuzzy adaptive PID; expressway; lane change warning; DSP algorithm; yaw rate.
New energy vehicle lithium battery life prediction method based on improved deep learning
by Zhiwen An
Abstract: The traditional methods of life prediction of lithium battery in new energy vehicles have the problems of large error and low efficiency. The paper puts forward a new energy vehicle lithium battery life prediction method. The capacity, internal resistance, terminal voltage and charge discharge cycle parameters of lithium battery for new energy vehicles are extracted to determine the key parameters affecting the life of lithium battery; The gradient descent method is used to improve the deep learning algorithm, and the improved deep learning prediction model is constructed. The key parameters affecting the lithium battery life are taken as the input of the model, and the optimal value is found to predict the lithium battery life of new energy vehicles. The results show that the capacity estimated by the proposed method is basically consistent with the actual capacity, and the life prediction time is always less than 2.2 s.
Keywords: improving deep learning; lithium batteries; voltage curve; key parameters; life prediction.
Path guidance method for unmanned vehicle based on improved potential field ant colony algorithm
by Zhuozheng Tang, Hongzhong Ma
Abstract: In order to overcome the problems of traditional path guidance methods such as long time consumption and many intermediate nodes in path planning results, a path guidance method for unmanned vehicles based on improved potential field ant colony algorithm is designed in this paper. From improved potential field function, pheromone update process and heuristic function 3 Angle improved potential field of ant colony algorithm, improve the obstacle avoidance ability of ant colony individuals and search capabilities, and then by determining the starting point and focus of elliptic search scope, in order to improve the optimal planning path searching efficiency and can achieve the optimal guide path. Experimental results show that the maximum time to generate the path guidance scheme is only 3.7s, the maximum TPI of the road is only 0.27, and the intermediate nodes of the planned path are the least and all paths are the shortest.
Keywords: improved potential field ant colony algorithm; labour market; driverless vehicles; path to guide.
Wear life prediction of vehicle brake pads based on image visual features
by Zuokui Li, Ruibin Jiang
Abstract: In order to solve the problem of poor prediction accuracy and stability existing in traditional prediction methods of vehicle brake pad wear life, this paper proposes a new prediction method of vehicle brake pad wear life based on image visual features. According to the visual features of the image, the gray moment features of the image are extracted, and the adaptive binary clustering is used to extract the target contour from the image. Aiming at the areas with different visual brightness, a three-dimensional physical model is established, and the friction coefficient and other parameters are calculated. Combined with the material characteristics of the brake pad, the wear life of the brake pad is predicted. The experimental results show that the proposed method has high detection accuracy, high level of stability maintenance, and its prediction reliability is improved. The maximum mutation index is less than 0.1.
Keywords: image visual feature; vehicle braking; brake pad; wear life prediction;.
Vehicle abnormal jitter detection based on multi-task convolutional neural network
by Jun Liu, Xiaoyuan Luo
Abstract: In order to overcome the problems of poor convergence, long detection time and high misjudgment rate existing in traditional methods, this paper proposes a vehicle abnormal jitter detection method based on multi-task convolutional neural network. The causes of abnormal vehicle jitter were analysed, and the equivalent taper of vehicles under different mileage was calculated to obtain the abnormal vehicle jitter frequency, and the time-frequency characteristics of vehicle vibration were obtained. The multi-task convolutional neural network is used to establish the calculation model of wheel matching geometric relationship under the condition of dithering, and the dithering degree of the vehicle body at different moments is obtained by sections, so as to realise the detection of abnormal vehicle dithering. The convergence coefficient of the method in this paper is higher than 0.9, the detection time of abnormal jitter is always below 1.2 s, and the lowest misjudgment rate is only 0.6%.
Keywords: multi-task convolutional neural network; dithering detection; integral method; dithering frequency; equivalent taper.
Ride comfort parameter optimization of an 8x8 armoured military vehicle using Taguchi method
by Berkay Celik, Namik Kilic
Abstract: Design parameters in military vehicles at the conceptual design stage have an impact on the results that will affect the fatigue of the driver. This article suggests the Taguchi optimization method to determine the most comfortable design parameters for the driver of an 8x8 military vehicle in difficult terrain conditions. Taguchi is an experimental design method that makes it possible to achieve results with a much smaller number of experimental studies. The full vehicle model prepared in MSC Adams/Car was driven over the Aberdeen Proving Ground (APG) stabilization track and performed a double lane change test to get experiment results for Taguchi design. The objective function of the optimization was the amount of absorbed power generated in the driver's seat over the APG track. In addition to this, roll angle results in the double lane change test were evaluated in the optimization procedure. In the study, it was found which of the design parameters had a significant effect on vehicle ride comfort and handling. The equations that estimate both the vehicle ride comfort and the vehicle handling according to the design parameters were obtained. This study improved the ride comfort of a four-axle military vehicle driver using the Taguchi method and developed a procedure that could be used in future design studies.
Keywords: military vehicle; ride comfort; optimisation; Taguchi method; absorbed power.
Wear life prediction of vehicle mechanical parts based on grey Markov chain
by Haoge Peng, Ming Zhang
Abstract: In order to overcome the high prediction error rate of traditional methods, a wear life prediction method of vehicle mechanical parts based on grey Markov chain is proposed. The wear type, wear mechanism of vehicle mechanical parts and the relationship between wear type and surface damage form are analysed, and the wear amount of vehicle mechanical parts is calculated. Based on the calculation results of wear amount, the relative error and residual error of wear life prediction results based on GM (1,1) model are obtained by using Markov chain, and the wear life prediction results of vehicle mechanical parts are obtained under the condition of minimising the two. The experimental results show that the accuracy of this method is 58-92%, the maximum error rate is 4.5%, the minimum error rate is 0.9%, and the average output time is 1.16 s.
Keywords: grey Markov chain; mechanical parts; wear life prediction; relative error; predicting residual.
Vibration fault detection of vehicle transmission gearbox based on time-frequency analysis of non-stationary signals
by Zhongli Shen, Qiyue Xie, Fei Jiang, Yi Huang
Abstract: The traditional vibration fault detection method of vehicle transmission gearbox cannot realise feature extraction of a non-stationary fault signal, which results in a large error of detection and low fault detection rate. Therefore, this paper proposes a new method of vehicle transmission gearbox vibration fault detection based on non-stationary signal time-frequency analysis. The components of the transmission gearbox are analysed, and the transmission path of vibration fault signal of transmission gearbox is obtained according to its structural characteristics. The time-frequency characteristics of non-stationary signals are extracted by the empirical mode method to complete the vibration fault detection of the transmission gearbox. Experimental results show that the proposed method has high detection accuracy and high detection rate under the premise of amplitude and phase modulation of fault signal.
Keywords: vehicle transmission gearbox; vibration fault; non-stationary signal; time-frequency analysis; optimal observation signal.
Design of BLDC motor drive system using alternative controllers for performance evaluation in electric vehicle applications
by Mohamraj Nandakumar
Abstract: Electric vehicles have emerged as a promising and important alternative means of transportation, replacing IC engine driven automobiles, which use fossil fuels. One important feature to be incorporated in an electric automobile is regenerative braking for extending the operating range. Accordingly, BLDC motor-based power electronic drive systems capable of energy regeneration have become attractive. This paper discusses the automobile dynamics, covering road friction, aerodynamic forces, transmission systems and calculation of tractive force. The time dependant profile of the reflected torque and speed variables at the motor shaft are computed and used as reference data for an intelligent controller. Here, a multi-loop control scheme has been developed, whose gain parameters are tuned based on two alternate algorithms viz., PSO (Particle Swarm Optimisation) technique and MNFIS (Multiple Neuron Fuzzy Inference System) for comparison. Simulation results for two power circuit regeneration topologies with the above control algorithms are presented. The experimental part is a representation of profile based operation, which deals with the application of the PMBLDC motor-based drive system for powering a passenger car and the evaluation of the system performance. Regeneration of power is validated in a laboratory setup and recorded.
Keywords: BLDC motor; electric vehicle; MNFIS; PSO.
Special Issue on: Advanced Safety Design and Control for Electric Vehicles
Research on stability of high-speed autonomous vehicles based on linear time-varying model predictive control
by Xiaoming Liu, Fei Liu, Jingbo Guo
Abstract: A stability control method of high-speed autonomous vehicles based on linear time-varying model predictive control (LTV-MPC) considering the impact of road environment is proposed. To ensure the accuracy of the prediction model and the driving stability of the vehicle, a yaw dynamics model is established considering the road curvature, lateral position deviation and tire slip rate. In order to reduce the influence of the road environment on path following effect, the reference road is segmented by B
Keywords: autonomous vehicles; linear time-varying model predictive control; MPC; dynamics; handling stability; road curvature; path following.
Steering and braking combined path tracking control considering the reserve potential of tyre force
by Shaosong Li, Feng Wang, Haitian Xu, ZongHao Li, Gaojian Cui
Abstract: The coordination control of the steering and braking system is the key technology for vehicle stability control under high-speed and low adhesion limit conditions. The concept of equal reserve capacity of tyre longitudinal and lateral forces is proposed in this paper, which provides a novel idea for tyre force distribution. On this basis, a steering and braking combined path tracking control method based on model predictive control is proposed to guarantee vehicle path tracking performance. Research results show that the proposed method enables the vehicle to steadily and accurately track the planned trajectory under high-speed and low-adhesion condition. Compared with the schemes in other methods, the reserve margin of the tyre force is greatly improved in the proposed method, thus enabling the tyre to exert greater control potential.
Keywords: trajectory tracking; steering and braking combination; model predictive control; reserve potential of tyre force.
A new torque ripple suppression strategy based on the CSA for PMHM of electric vehicles under New European Driving Cycles
by Yao Zhang, Xiaodong Sun
Abstract: This paper presents a new torque ripple suppression strategy for a permanent magnet hub motor (PMHM) of electric vehicles' drive. With the complex characteristics such as nonlinear time delay and multi-dimension presented by the PMHM, the traditional PID controller has been unable to meet the requirements of the control system. Thus, the cat swarm algorithm (CSA) is introduced to improve the accuracy of PID parameters thanks to its good global search ability. Moreover, it is found that the proposed CSA-PID in the outer loop can obtain better performance such as smaller torque ripple and faster dynamic response both in steady and dynamic state compared with the traditional PID controller. Finally, the strategy proposed in this paper was applied to the vehicle model through HIL test platform. The possibility of applying the strategy proposed to EVs was verified under the New European Driving Cycle.
Keywords: permanent magnet hub motor; cat swarm algorithm; torque ripple suppression; New European Driving Cycle.
Research on crashworthiness and lightweight of frame body based on load path and material selection
by Tingting Wang, Ruoyan Dong, Yuechen Duan, Dongchen Qin
Abstract: In order to effectively optimise the frame body structure and match the performance of lightweight materials with the function of body structure, a material-structure optimisation framework of multi-material frame body is proposed to improve the lightweight and collision safety at the same time. Firstly, in order to improve the crashworthiness of the frame, the equivalent static load method is used to analyse the load path of the frame body to obtain the optimal structure. Secondly, the crashworthiness evaluation method based on evolutionary structural optimisation method is used to evaluate each member of frame body, which provides the basis for material selection. Finally, the material index is introduced to establish the material library. According to the deformation evaluation results, the material selection method based on bubbling method is used to select materials orderly to match the function of members, and the multi-material frame with the objective selection scheme is obtained. In this study, the proposed method is demonstrated by the lightweight of racing car body. The results show that the body mass is reduced by 25.60 kg after the lightweight design, and the crash safety is improved. Therefore, the proposed optimisation framework of multi-material frame body.
Keywords: frame body; lightweight; load path; material selection.
Special Issue on: Advanced Design and Automation Solutions for Offshore Vehicles
Network-based formation control of unmanned autonomous systems with directed topologies
by Wenjian Zhong, Yuanqing Wu, Yanzhou Li
Abstract: The formation control of unmanned autonomous systems with nonlinear dynamics and directed topology is studied in this paper. By virtue of an ultra-wide bandwidth (UWB) localisation system, the relative position between each follower and the neighbouring agents can be obtained. A formation control condition for unmanned autonomous systems is derived by appropriately constructing a Lyapunov function. Further, a formation controller is designed to form the formation of all autonomous agents and reach the consensus of velocities. Some parameters are designed to ensure the feasibility of the formation controller. The effectiveness of the formation control protocol is verified by numerical simulations.
Keywords: unmanned autonomous systems; formation control; directed topology; ultra-wide bandwidth.
FlameNet: a lightweight convolutional neural network for flame detection and localisation
by Xing Hu, Mei Li, Dawei Zhang
Abstract: Accurately and efficiently detecting and localising the flame is critical for preventing fire disasters. However, most high-performance deep models require high hardware resources, making them hard to deploy on edge or mobile intelligent devices with limited computation and storage resources. This paper proposes a lightweight deep convolutional neural network, called FlameNet, for flame detection and localisation in the real world. The proposed FlameNet is derived from YOLOv4 with the following modifications: first, MobileNetV2 replaces the CSPDarknet53 as the new backbone network of YOLOv4; second, the coordinate attention module is added to the inverted residual linear bottleneck of MobileNetV2; third, the depthwise separable convolutions is used in PANet of YOLOv4. The above modification significantly reduces the number of parameters and computation and improves detection accuracy. Considering the diversity and complexity of flames, and that no large-scale public dataset is available, we make a Real-World Flame (RWF) dataset containing 13,129 images from actual flame and fire disasters in real life. Qualitative and quantitative analysis and comparisons of experimental results demonstrate that the accuracy and efficiency of the proposed FlameNet for flame detection outperform the original YOLOv4 and the other relevant models. It is worth noticing that the number of parameters is only 1/6 of the original YOLOv4, which demonstrates that FlameNet is more suitable for deploying on edge or mobile devices.
Keywords: flame detection; flame localisation; FlameNet; lightweight model.
Integrated behaviour decision-making and trajectory tracking for dynamic collision avoidance of an ASV using receding horizon optimization
by Jian Zheng, Duowen Yan, Jiayin Hu, Yun Li
Abstract: This paper develops a receding horizon optimisation scheme for integrated behaviour decision-making and trajectory tracking to ensure the dynamic collision avoidance of an autonomous surface vessel (ASV). We apply Q-learning to make behaviour decisions because manoeuvring habit requirements and COLREGS must be satisfied in dynamic collision avoidance scenarios. The heading course and vessel speed are considered to transmit the outcome of behaviour decision-making to a trajectory tracking model predictive control (MPC) controller. Next, a trajectory tracking nonlinear controller for the ASV is developed within the MPC framework, in which a set of nonlinear constraints is designed for collision avoidance. Specifically, depending on the heading course and vessel speed, the collision avoidance constraints can be switched to allow the controller to execute the behaviour decision. Simulation results verify the effectiveness of the proposed receding horizon optimisation scheme.
Keywords: Q-learning; trajectory tracking; dynamic collision avoidance; unmanned surface vessel; model predictive control.
Compressive sealing process in vehicle engineering
by Menghan Tong, Shichao Xiu, Xiaoshan Chen, Siyu Chen
Abstract: The paste reliability of sealing strips is very important for the continuous quality of vehicle NVH. Compared with straight-line paste and outer corner paste, the inner corner paste of the sealing strip is more likely to be invalid. To improve the inner corner paste reliability of the sealing strip, a compressive pasting process is proposed. The additional pressure generated by the compressive pasting process was also studied. A calculation model of the pressure on the inner fillet produced by the sealing strip is proposed, allowing the pressure to be calculated by the compression ratio. The additional pressure on the inner circle structure caused by the compression of the sealing strip was simulated. A pressure experiment of the compressive sealing strip was completed. The relationship between the compression and additional pressure from the sealing strip was obtained and verified.
Keywords: vehicle engineering; sealing strip; compressive sealing; additional pressure; PSA; finite element analysis; capability study; molecular force; mechanical model.
Image-based visual servoing of underwater vehicles for tracking a moving target using model predictive control with motion estimation
by Jie Liu, Jian Gao, Weisheng Yan, Yimin Chen, Bo Yang
Abstract: This paper introduces an image-based visual servoing (IBVS) target-tracking strategy for an underwater vehicle to track a moving target beneath the vehicle using a downward-facing camera. The relative position, orientation, and velocity of the moving target were estimated using a nonlinear unscented Kalman filter (UKF). Based on these estimated values, image Jacobian matrices with respect to the velocities of the vehicle and target were constructed. A nonlinear model predictive controller (MPC) was employed to generate the velocity commands for underwater vehicles by optimising the visual target trajectories predicted by the estimated image Jacobian matrix and the target velocity. To track the velocity commands, an adaptive neural network controller was employed considering the system uncertainties. Simulation tests were performed with a fully actuated underwater robot to verify the efficiency of the designed IBVS target-tracking strategy.
Keywords: underwater vehicles; image-based visual servoing; moving target tracking; model predictive control; neural network; unscented Kalman filter.
Experimental validation of an improved underwater sphere-target localisation scheme for an autonomous underwater vehicle manipulator system
by Tianchi Zhang, Yong Tan, Xing Liu, Zhenzhong Chu
Abstract: In this study, an underwater sphere-target localisation method based on non-parallel binocular vision for an autonomous underwater vehicle manipulator system (AUVMS) is investigated. Existing extraction methods for underwater targets require considerable processing time, such that the real-time requirements for an AUVMS are not satisfied, and the shape features of the targets are not considered. In this study, an underwater target extraction method with reduced processing time is developed based on the known target edge constraint. The experimental results show that the developed method requires less time than the existing target extraction methods and satisfies the real-time requirements. In addition, the localisation precision of existing target localisation methods is relatively low, which leads to a low rate of successful implementation for an AUVMS. To solve this problem, a secondary compensation-based target localisation method is developed. A theoretical analysis is also presented. The experimental results show that the developed target localisation method can effectively improve the localisation accuracy and rate of successful implementation.
Keywords: AUVMS; target extraction; target localisation; secondary compensation; binocular vision.
Method of improving the soil compactor's ride quality based on the optimal negative stiffness structure
by Nguyen Van Liem, Dengke Ni
Abstract: A new driver's seat suspension designed by the negative-stiffness-structure (NSS) and cab's isolation used by the hydraulic mounts are proposed to enhance the soil compactor's ride quality. A nonlinear vehicle dynamics model that considers the interaction between the wheel/drum and deformable terrains is established to evaluate the NSS's performance. Based on the genetic algorithm, NSS's parameters are optimised to further improve ride quality. The ride quality is evaluated through the displacement and acceleration of the seat and cab in the frequency and time domains. The research results are also verified via experiments. The results show that the root-mean-square (rms) and power-spectral-density of the seat and cab accelerations with the optimal NSS are strongly reduced in comparison without NSS. Especially, the rms seat's acceleration is markedly attenuated by 67.54% under the vehicle working condition. Therefore, the optimal NSS applied on off-road vehicle's seat suspension could enhance the ride quality.
Keywords: soil compactors; seat suspension system; negative stiffness structure; ride quality; multi-objective genetic algorithm; off-road terrains.
An algorithm for solving the travelling salesman problem based on improved particle swarm optimisation and dynamic step Hopfield network
by Jiahao Wu, Qianqian Duan
Abstract: The travelling salesman problem (TSP) is a typical combinatorial optimisation problem. Many practical applications, such as logistics distribution centre location and network routing design, can be transformed into TSP by simplification. With the increase in city scale, the optimal solution is difficult to calculate. Therefore, it is necessary to find an efficient and feasible solution algorithm. An algorithm based on improved particle swarm optimisation and a dynamic step Hopfield neural network is proposed in this paper. Simplify the energy function to reduce the parameters of the energy function and improve the calculation efficiency; because of the slow convergence speed of the Hopfield network with the fixed step size, the dynamic step size is used instead. At the same time, aiming at the problem that Hopfield easily falls into local minima, the idea of particle swarm optimisation is introduced. According to the idea of exchange sequence, the particle swarm optimisation algorithm is redefined. On this basis, the random inertia weight is used to enhance the searching ability, and the asynchronous learning factor is used to enhance the learning ability of particles. Experiments show that compared with the classical Hopfield network, this algorithm can accelerate the convergence speed, better avoid invalid solutions, jump out of possible local extremum points, and obtain the global optimal solution with higher probability.
Keywords: Hopfield; travelling salesman problem; dynamic step size; PSO; random inertia weight; Asynchronous
Leader-follower formation transformation control based on priority model for unmanned surface vehicle in narrow waters
by Linling Wang, Gongxing Wu, Hao Luo
Abstract: This paper presents a strategy of formation generation and formation transformation for multiple unmanned surface vehicles (USVs) in narrow waters. In order to solve the problem of multi-USV transformation in narrow waters, priority model and virtual intermediate goal are adopted. Multi-USV formation can successfully pass narrow waters while maintaining its shape by using this method. The formation generation and transformation are controlled by back-stepping based sliding motion controller (BSMC). The combination of back-stepping method and sliding motion control has high robustness, and can deal with the unmatched uncertainty problem, which can ensure the real-time performance of the control and is easy to deploy on the actual USV. The simulation results show that the method can make the formation change quickly in narrow waters and make the formation pass smoothly, and the error converges to 0 in finite time.
Keywords: formation control; formation transformation; priority model; multi-USV.