International Journal of Vehicle Design (14 papers in press)
Hybrid power train efficiency improvement by using electromagnetically controlled double-clutch transmission
by Antoni Szumanowski, Yuhua Chang, Zhiyin Liu, Pawel Krawczyk
Abstract: This paper proposes a new type of hybrid powertrain with a specially designed double-clutch transmission. Compared with the existing hybrid powertrains, the proposed solution with double-clutch transmission, based on innovative double-clutch and mechanical gear sets, has the potential to achieve higher levels of performance efficiency at a lower production cost. The impact factors of system efficiency are analysed on a dynamic non-linear simulation model. The control strategies of powertrain and the double-clutch transmission gear ratios are studied by simulation results. Additionally, the double-clutch transmission can increase the efficiency of regenerative braking.
Keywords: hybrid power train; efficiency; double-clutch transmission; simulation.
On crashworthiness design of double conical structures under oblique load
by Yong Zhang, Jin Wang, Tengteng Chen, Minghao Lu, Feng Jiang
Abstract: A novel multi-cell tube with non-collinear outer and inner conical angles (MBCT) is proposed to enhance structural performance under different load conditions. The finite element models are developed and validated by experimental tests. The comparative analysis is carried out to investigate the crashworthiness of different conical structures among MBCT, multi-cell conical tube (MCT), multi-cell bi-tubular straight tube (MBST) and bi-tubular conical tube (BCT). The results indicate that MBCT has the most desirable load characteristics and highest energy absorption capacity, owing to its efficient cross-section design and conical configuration. Furthermore, parametric studies reveal that a large outer conical angle facilitates energy absorption and desirable load characteristics. Large wall thickness, on the other hand, has conflicting effects on crashworthiness since it increases peak crushing force but cannot improve special energy absorption. Crashworthiness assessment of a MBCT crush box in a full vehicle further indicates the merits of energy absorption of double conical structures under oblique load. The study offers insights on designing energy absorbers that are both weight efficient and reliable under uncertain load conditions.
Keywords: double conical structure; crashworthiness; oblique load; energy absorption.
Vehicle subsystems energy losses and model-based approach for fuel efficiency estimation towards an integrated optimisation
by Nikola Holjevac, Federico Cheli, Massimiliano Gobbi
Abstract: Improvement of the energy efficiency of passenger cars has nowadays become crucial for automotive companies: public awareness on environmental issues and sustainable development, stringent policies and regulations, conventional fuel future availability and competition in market share. Energy loss assessment requires experimental procedures; this process is time consuming and expensive, thus virtual methods have been increasingly employed during the design process. Model-based approaches have been widely used in the design of vehicle subsystems and components, however current methodologies focus on specific areas while only a few attempts to cover the entire vehicle system have been proposed. In this paper, energy losses of vehicle subsystems are analysed through a comprehensive literature review. Simple models are then presented to evaluate steady-state performances and efficiency of subsystems. The different modules are then coupled to simulate the entire vehicle behaviour while facing different driving scenarios and allowing to assess fuel economy and to evaluate the effect of design variations and new technologies.
Keywords: automotive; efficiency assessment; fuel economy; model-based approach; powertrain; vehicle architecture; optimisation.
Matching and optimising analysis of multi-axle steering vehicle steering system
by Yunchao Wang, Chengzhi Wang
Abstract: The analysis of the multi-axle steering link mechanism (MASLM) link forces provides the foundation for the mechanisms design. The matching level between the steering cylinder driving torque and the tyre pivot steering resistance torque can dramatically influence the link forces. In this study, the accuracy of the tyre resistance torque formula reached at 90.7%. A steady kinematic-mechanical coupling model of the MASLM was built modularly, and a method of calculating the link forces and steering hydraulic pressure is proposed. To verify the coupling models, an all-terrain QAY130 crane was chosen for simulation and testing. Two vehicle models were built by using the Adams and Matlab software, respectively. The discrepancies were less than 23.5% between the test values and the predicted values for the previous two models, but exhibited similar variation trends. The installation site and diameter parameters of the steering cylinders were optimised to minimise the link forces.
Keywords: multiple axle steering; steering link mechanisms; link forces; kinematic mechanical coupling models; pivot steering; tire resistance torque; matching level; matching design; optimal design.
Estimation of tyre forces using smart tyre sensors and artificial intelligence
by Jennifer Bastiaan
Abstract: In-tyre strain measurements from a smart tyre sensor system are analysed using two artificial neural network types, with the objective of estimating tyre forces. A tyre finite element model is used to calculate in-tyre strain (inputs) and tyre forces developed at the wheel centre (outputs) for use in the neural networks. Neural networks are trained on pure slip conditions and tested on combined slip conditions with the goal of accurately predicting tyre longitudinal and lateral forces and tyre aligning moment in combined slip events. The large mapping function is fitted using multilayer perceptron networks and radial basis function networks. Results from the radial basis function networks are excellent, with calculated tyre forces within 1% and tyre aligning moment within 14% for the best network design; training times are less than one minute and testing times are around 0.004 second. The conclusion is that radial basis function networks can be used effectively for real time analysis of strain sensor measurements in a smart tyre sensor system. Further studies using the radial basis function networks show that the system should have two in-tyre strain sensors located near one another at the outside sidewall, with one oriented longitudinally and the other oriented radially.
Keywords: smart tyres; strain measurement; vehicle dynamics; tyre dynamics; vehicle safety; intelligent vehicles; intelligent systems; artificial neural networks; multilayer perceptron networks; radial basis function networks; finite element analysis.
Estimation of road transport vehicle dynamic characteristics using random decrement analysis and on-the-road vibration data
by Daniel Ainalis, Vincent Rouillard, Michael Sek
Abstract: This paper presents the application of a recently developed and validated approach to accurately estimate the sprung mass mode dynamic characteristics of road transport vehicles using only on-the-road vertical vibration response data during constant speed operation. A description of the developed analytical approach using the random decrement technique and the Hilbert transform is included. Three experimental case studies are presented, each using a different road transport vehicle travelling at various nominally constant operating speeds over different roads to demonstrate the ability of the on-the-road approach to practically estimate the sprung mass modal properties, namely natural frequency and damping. The estimated dynamic characteristics were compared with different experimental procedures currently in use, including response-only (transient), and excitation-response methods. The new method provides a simpler, cost effective, and practical approach to obtain reliable and realistic estimates of the sprung mass mode natural frequency and damping ratio.
Keywords: road vehicle vibration; frequency response function; random decrement; vehicle dynamics; random vibration; ride comfort.
Advanced approach for layshaft gear set synthesis
by Johannes Ruschhaupt, Gereon Hellenbroich
Abstract: A new systematic synthesis approach for layshaft gear sets is presented in this article. Common synthesis methods generate on part level the complete solution space of all possible gear sets, from which the optimum solution is selected by various evaluation criteria. In the presented new approach, the complete solution space of abstract "gear set structures" is initially generated. The gear set structure is a simplified representation of the degrees of freedom and connections of a certain gear set, based on which a fast and systematic analysis of significant gear set characteristics is possible. In the following step the gear set layout, which represents the arrangement of gear-wheels and shift elements, is developed based on the optimized gear set structure. Based on exemplary requirements, a detailed gear set for a dual clutch transmission has been developed to validate and demonstrate the process. The dual clutch transmission with two main axes, four synchronizer units and seven gear tracks offers nine forward speeds and one reverse speed.
Keywords: synthesis methods; gear set structures; gear set layouts; gear set development; gear set models; utility analysis; gear set evaluation; layshaft transmissions; dual clutch transmissions; multi-speed transmissions; generated gears.
Comparison of dual and single clutch transmission based on global transport application mission profiles
by Pär Pettersson, Sixten Berglund, Henrik Ryberg, Gunnar Karlsson, Lennart Brusved, Johan Bjernetun, Bengt Jacobson
Abstract: Global Transport Application (GTA) is a common language used to define transport missions for development, sales and aftermarket processes. To achieve a light weight and low-cost powershifting transmission for the targeted heavy vehicle applications, GTA was used in the development of the I-Shift Dual Clutch (I-Shift DC). Using a well-defined transport mission enables relevant modelling and simulation for performance assessment. This paper outlines the methods and shows some examples of technical implications. Firstly, the results from real world measurements in one specific scenario are presented. This shows the difference between a single clutch (SC) and a dual clutch (DC) transmission for heavy-duty vehicles. Secondly, a full vehicle simulation model is built to extend the results to longer transport missions. The measurement results are used to parametrise and calibrate the model. Finally, the calibrated model is used to evaluate the performance in detail by using GTA to select appropriate transport missions for simulation.
Keywords: commercial vehicles; dual clutch transmission; transport mission; powertrain optimisation; global transport application; I-Shift DC.
Optimal design of power-split hybrid tracked vehicles using two planetary gears
by Zhaobo Qin, Yugong Luo, Ziheng Pan, Keqiang Li, Huei Peng
Abstract: Power-split hybrid powertrains have been thus far successfully used for production passenger cars and SUVs but not for tracked vehicles. For example, track-type dozer (TTD) models available on the market tend to use series hybrid powertrains, which frequently require a separate steering mechanism, resulting in lower operating efficiency and the need for large space arrangements. Looking to the future, power-split hybrid technologies have high potential for tracked vehicles to circumvent the limitation. This paper proposes a design process for multi-mode power-split powertrains for TTDs. The powertrain consists of one engine, two motors, and two outputs connected independently to the left and right tracks. This powertrain is designed to achieve separate control of the two sides of the tracks to enable skid steering. In addition, multi-mode ensures that the powertrain can realize central steering and driving backwards using the engine power. To systematically search for all possible designs with two planetary gears, an optimal methodology is proposed. By establishing two characteristic matrices, an automated modeling process is proposed to obtain the dynamic equations quickly and efficiently. A near-optimal energy management strategy call PEARs+ is used to achieve near-optimal fuel economy. The approach successfully identifies two designs that achieve better overall performance compared with the benchmark.
Keywords: hybrid tracked vehicles; power-split hybrid vehicles; optimal design.
Trajectory tracking control of four-wheel steering under high speed emergency obstacle avoidance
by Runqiao Liu, Minxiang Wei, Wanzhong Zhao
Abstract: In order to solve the problem of trajectory tracking for 4WS autonomous vehicles under high speed emergency obstacle avoidance, an improved trajectory tracking controller combined four-wheel steering (4WS) feed-forward control and linear quadratic regulator (LQR) feed-back control is proposed. First, a polynomial obstacle avoidance trajectory of small radius and sharp curve is established and its several variables are analysed. Second, in order to make actual yaw rate follow a steady-state value based on the reference model, the steering gain of the improved 4WS feed-forward control can change with steering angular frequency and vehicle speed. Third, combined with the LQR feed-back control, the deviations between actual lateral displacement and desired lateral displacement are controlled under 0.05 m. Finally, CarSim
Keywords: 4WS autonomous vehicle; emergency obstacle avoidance; steering angular frequency; linear quadratic regulator; trajectory tracking.
Special Issue on: Recent Advances in Sensing Technology, Vehicle Control Systems and Tyre Design Considerations for Electric and Autonomous Vehicles
Vehicle longitudinal force estimation using adaptive neural network nonlinear observer
by Mourad Boufadene, Mohammed Belkheiri, Abdelhamid Rabhi, El Hajjaji Ahmed
Abstract: This paper presents an adaptive neural network (ANN) nonlinear observer to estimate the longitudinal tyre forces as well as the lateral speed, which is not measured on standard vehicles. The proposed ANN observer uses the longitudinal speed, yaw rate and the steering angle dynamics of the vehicle as measured states. It is used to estimate the states, and the longitudinal tyre forces, which are unknown dynamics, with high performance. The obtained simulation results show the effectiveness of the proposed neural network nonlinear observer.
Keywords: adaptive observer; adaptive neural network; radial basis function
approximation; nonlinear observer; vehicle force estimation; tyre forces
estimation; longitudinal vehicle force estimation.
Integrated control of AFS and DYC for in-wheel-motor electric vehicles based on operation region division
by Jianjun Hu, Zhihua Hu, Chunyun Fu, Fuqian Nan
Abstract: The integrated chassis control system can improve vehicle handling and stability effectively. This paper proposes an integrated control system based on operation region division of AFS and DYC for in-wheel-motor electric vehicles. The control system adopts a two-layer hierarchical control structure. The decision layer employs a modified sliding mode controller to calculate the required corrective yaw moment, and determines operating regions of the two subsystems based on the driving conditions (road adhesion coefficient, tyre load and wheel slip ratio). The execution layer generates the corrective steer angle and the driving/braking toques for the AFS and DYC subsystems respectively. Simulation results show that on the high-adhesion-coefficient road, the integrated control system appropriately adopts subsystems to improve handling, while attenuating the workload of barking system; on the slippery road, the integrated control system maintains vehicle stability and provides superior control performance to those resulting from the single systems.
Keywords: driving stability; AFS; DYC; yaw rate; hierarchical control; operation region division; lateral tyre force; Magic Formula; sliding mode control.
Pressure control of integrated electro-hydraulic braking system considering driver braking behaviour
by Hao Pan, Xuexun Guo, Xiaofei Pei, Daoyuan Sun
Abstract: This paper proposes a pressure controlling strategy for the Integrated Electro-Hydraulic Braking (IEHB) system when considering driver braking behaviour. Firstly, the representative feature parameters of braking behaviour are extracted from various vehicle data and clustered by manoeuvre characteristics. Seven brake pedal operation training libraries are self-learned adaptively by hidden Markov model for driver braking behaviour recognition. Then, a self-tuning function based on recognition results is proposed to adjust the PWM parameters of the PI controller for the motor and valve. Eventually, the hardware-in-loop results of IEHB system show the accuracy of braking behaviour recognition algorithm, and the feasibility of self-tuning control strategy. In addition, the effectiveness of pressure regulation for the IEHB system is verified.
Keywords: electro-hydraulic braking system; braking behaviour; hidden Markov model; pressure control; self-tuning PI.
Active steering control system for an independent wheel drive electric vehicle
by M.A. Khan, M.F. Aftab, E. Ahmad, Iljoong Youn
Abstract: This research presents an active steering control system (ASCS) for an independent wheel drive electric vehicle (EV). The ASCS will manoeuvre the independently actuated (IA) all-wheel drive (AWD) EV via coordinating the angular velocities of the four wheels plus active front steering (AFS). Owing to the physical and mechanical limitations of the steering input in conventional AFS, the differential speed between left and right wheels of an IA EV is used to generate the additional steering effects. The ASCS is designed using the linear model of the vehicle and is tested in simulations using the nonlinear vehicle model. The proposed ASCS is a combination of forward speed and yaw rate controllers, designed using the robust $H_infty$ control methodology. The effectiveness of the proposed control system is analysed by comparing the performance of an AWD IA EV with ASCS, a rear wheel drive (RWD) IA EV with ASCS, a vehicle with AFS only, and a vehicle with no controller. The simulations results using a high-fidelity vehicle model under different driving conditions and road disturbances, indicates that the proposed system can significantly improve the vehicle performance by tracking the desired yaw rate and speed.
Keywords: differential steering control; active front steering; electric vehicle; four wheel drive; nonlinear vehicle model; steering control; vehicle dynamics; yaw rate tracking.