International Journal of Vehicle Performance (22 papers in press)
Load torque estimation for an automotive electric rear axle drive by means of virtual sensing using Kalman filtering
by Robert Kalcher, Katrin Ellermann, Gerald Kelz
Abstract: Load torque signal information in hybrid or battery electric vehicles would be beneficial for control applications, extended diagnosis or load spectrum acquisition. Due to the high cost of the sensor equipment and because of the inaccuracies of state-of-the-art estimation methods, however, there is currently a lack of accurate load torque signals available in series production vehicles. In response to this, this work presents a novel model-based load torque estimation method using Kalman filtering for an electric rear axle drive. The method implements virtual sensing by using measured twist motions of the electric rear axle drive housing and appropriate simulation models within a reduced-order unscented Kalman filter. The proposed method is numerically validated with help of sophisticated multibody simulation models, where influences of hysteresis, torque dynamics, road excitations and several driving manoeuvres such as acceleration and braking are analysed.
Keywords: load torque estimation; electric rear axle drive; virtual sensing; Kalman filtering; unscented Kalman filter; UKF; reduced-order unscented Kalman filter; ROUKF; hybrid electric vehicles; HEV; battery electric vehicles; BEV; multi-body simulations; MBS; vehicle systems modelling.
Deep reinforcement learning-based energy management strategy for hybrid electric vehicles
by Shiyi Zhang, Jiaxin Chen, Bangbei Tang, Xiaolin Tang
Abstract: In recent years, with the development of new energy vehicle industry, the development potential of hybrid electric vehicles (HEVs) is increasing. As one of the key technologies, energy management strategy (EMS) has always been a hot research area for hybrid electric vehicles. This paper proposed a Deep Q-Network (DQN) based EMS for a parallel HEV. Simulation results after training show that, compared with the EMS based on dynamic programming (DP), the DQN-based EMS can achieve 8.38% of the fuel consumption gap while the calculation time is only 12.5%. By the computational advantage of neural network, the average output time of an action in each state is 1ms, which has the potential for real-time applications. Since the final EMS is parameterized and fitted by deep neural networks of deep learning, it is necessary to find further methods for the actual experimental scheme instead of simulation in the future.
Keywords: Hybrid electric vehicle; learning-based energy management strategy; deep reinforcement learning.
Racing Line Optimisation for an Advanced Driver Assistance System
by Falk Salzmann, Sofiane Gadi, Ingmar Gundlach
Abstract: This paper deals with an accurate, robust and efficient optimisation method for time optimal path planning on circular tracks. Starting with a general description of the problem, suitable method domains for time-optimal path planning are qualified. In terms of reproducibility and accuracy, we propose an algorithm combining a model and a policy-based method which takes car, track and driving data gathered from connected cars into account. Hence, it can provide a consistently learning as well as a sufficient constant time-optimal racing line on worldwide race tracks for different driver assistance purposes. We evaluated the calculated racing lines with respect to heuristic criteria like curve cutting behaviour and by comparing them to ones driven by professional race drivers.
Keywords: driver assistance; connected car; reinforcement learning; trajectory optimization; vehicle dynamics.
COMPREHENSIVE REVIEW ON DUAL CLUTCH TRANSMISSION
by MILINDAR S D, SANTOSH PRASANNA, BASKAR P
Abstract: In the current age, the automobile industry has been facing multiple challenges like stringent emission norms, surging fuel prices, and customer demand for better fuel efficiency. So they are finding all possibilities by which they can satisfy all the requirements. In case of available options for transmission systems, Automatic and Automatic manual transmission systems (with single clutch) are in demand despite manual transmission returning a better fuel efficiency, due to ease of driving in traffic. In addition, these automatic manual transmission systems also lack in performance and driving comfort due to jerky shifts, as compared to the manual transmission systems. To overcome these challenges, dual-clutch transmission systems are being used. This is also a type of Automatic manual transmission system but has two clutches in operation as compared to one in others. There are two shafts on which the gears are mounted such that usually odd gears are on one shaft and even gears are on another. This allows the gear to be shifted without disengaging the drivetrain from the engine. The lag observed in single clutch automatic manual transmission systems while disengaging/engaging the clutch is avoided and the vehicle accelerates uniformly. This gives the advantage to offer better fuel efficiency, performance, and better ride comfort. This literature work focuses on the evolution, classification, components, lubrication technologies, controllers, and control strategies involved in the operation, existing systems with case studies, and comparison of dual-clutch transmission with other types of systems.
Keywords: Dual clutch transmission; automatic manual transmission; transmission fluids; Automotive transmission systems; automatic manual transmission controllers.
Optimisation of the energy efficiency of a hybrid vehicle powertrain
by Mourad Ali Salah, Naceur Benhadj Braiek
Abstract: To minimise fuel consumption, automakers are committed to developing new architectures for more efficient engine powertrain systems. The substitution of conventional thermal engine by a hybrid powertrain provides an additional degree of freedom for the energy flow management between an electrical branch and a thermal branch to consume less fuel. Parallel architecture offers the best compromise between design simplicity and energy efficiency, with respect to other architectures as serial and mixed architectures. In this context, this work deals with energy modelling of a parallel powertrain architecture and fuel optimisation independently of the vehicle path. For this purpose, two energy models that express the instantaneous overall efficiency of the vehicle powertrain are designed, and a fuel optimisation algorithm is developed. Numerical simulation shows the significant energy saving offered by the hybrid vehicle provided with the proposed fuel management law, compared to the internal combustion engine of a conventional vehicle.
Keywords: parallel hybrid vehicle; powertrain systems; instantaneous overall efficiency model; fuel optimisation independently of the vehicle path; energy flow optimisation; numerical simulation; energy saving offered by hybrid vehicle.
Evaluation of worldwide harmonised light vehicles test procedure for electric vehicles using simulation
by Teoh Jia Xian, Stella Morris, Chew Kuew Wai
Abstract: The introduction of the worldwide harmonised light vehicles test procedure (WLTP) by UNECE aims to standardise the global drive cycle testing procedure in determining emission compliance and fuel consumption. This paper evaluates the performance and the effect of the new driving cycle on different electric vehicles, based on major regulatory drive cycles: NEDC, FTP 75 and JC08. Using Matlab's ADVISOR simulation, a hatchback of Nissan Leaf 2016, a sedan of Tesla Model S60 and a low power electric vehicle of Mahindra E2O Plus have been simulated and investigated. For the decently sized vehicles, the WLTP test cycle consumes the highest energy per unit distance. However, the low powered electric vehicle behaves differently due to the strategic low speed operation of the vehicle. The paper also encompasses a method to simplify the complex modelling of the vehicle in the drive cycle's simulation, yet maintaining sufficient accuracy in its final emission results.
Keywords: WLTP; worldwide harmonised light vehicles test procedure; driving cycle standards; electric vehicle; vehicle test procedures; ADVISOR.
Special Issue on: Recent Advances in Energy-efficient Research for Vehicle Performance Improvement
Research on regenerative braking strategies for hybrid electric vehicle by co-simulation model
by Han Guo, Jianwu Zhang, Wenran Geng, Huijun Cheng, Haisheng Yu
Abstract: Regenerative braking is an important factor in improving hybrid electric vehicle (HEV) fuel economy. This paper presents the simulation modelling of a power-split hybrid electric vehicle with different regenerative braking strategies. A co-simulation model is used to enhance the simulation capability for the hybrid vehicle performance and development of control strategy. AMESim is used to model the complex physical components including engine, transmission, motors, battery and hybrid vehicle, and the physical model is integrated with control model established by MATLAB/Simulink, which is required to operate the vehicle and the regenerative braking system through standard drive cycles. Simulation results show that a regenerative braking control strategy can recuperate significant amounts of energy. Vehicle fuel economy in EV and HEV modes is improved significantly by coupling the proposed regenerative braking strategy.
Keywords: hybrid electric vehicle; regenerative braking; energy management; AMESim; MATLAB/Simulink.
A new model predictive torque control strategy for permanent magnet synchronous hub motor of EVs
by Long Chen, Hao Xu, Xiaodong Sun
Abstract: This paper presents an optimal control strategy for a permanent magnet synchronous hub motor (PMSHM) of EVs drive using three voltage vectors. First, in order to simultaneously control torque and flux excellently, three voltage vectors including two active vectors and one zero voltage vector are selected. Second, the duration of the three voltage vectors in one period is calculated by the principle of simultaneous deadbeat control of torque and flux. Moreover, the cost function which eliminates the weight coefficient is proposed to reduce the amount of calculation. Finally, the proposed method is compared with the one- and two-vector-based model predictive torque control (MPTC) methods both in simulation and experiment. It is found that the proposed threevector-based MPTC can obtain better performance such as smaller torque ripple and current total harmonic distortion (THD) both in steady and dynamic state.
Keywords: EVs; electric vehicles; flux; cost function; MPTC; model predictive torque control; PMSHM; permanent magnet synchronous hub motor; three voltage vectors; torque.
Study on comprehensive performance of Ni-MH power battery used in HEV at different temperatures
by Xiang Chen, Yelin Deng, Xueliang Fan, Yinnan Yuan, Aihua Chu, Jianxin Zhu
Abstract: This study carries a comprehensive investigation on the influences of the key environmental and operating parameters on SOC and cycling life of the Ni-MH battery. The Ni-MH cells were tested through loading the actual road spectrum at different temperatures (25/35/45°C). Other parameters of SOC fluctuation and currents are set to be 10% and 15.5A by average, respectively. Tests have been performed to obtain the OCV (open circuit voltage)~SOC curves at different temperatures under the 1-C rate of charging/discharging. The investigation results show that the capacity decay compared to initial capacity is increased by a slight 2.46% at 45°C, demonstrating an excellent cycling performance of the Ni-MH battery. Additionally, the battery polarization effect is found to be correlated to the charging and discharging processes and temperature. In summary, this study presents a comprehensive factor analysis needed to achieve a reliable SOC estimate for the Ni-MH based HEV.
Keywords: Ni-MH battery; HEV; hybrid electric vehicle; polarisation effect; cycling life; SOC estimate; state of health; open circuit voltage; OCV.
Potential and challenges to improve vehicle energy efficiency via V2X: literature review
by Kai Yang, Yanjun Huang, Yechen Qin, Chuan Hu, Xiaolin Tang
Abstract: With the development of intelligent transportation system (ITS), vehicle-to-everything (V2X) information offers great opportunities to promote the energy efficiency of vehicles. This paper systematically elaborates the state of art which focuses on improving the energy efficiency using the vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-network (V2N) and vehicle-to-grid (V2G) technology. Firstly, V2V technology applied in energy management of single and vehicular platoon is investigated. Secondly, eco-driving for connected vehicles using V2I information is studied. Thirdly, the potential of enhancing the energy efficiency by the V2N communication between vehicles and network is analyzed as well. Fourthly, the utilisation of V2G technology to increase the energy efficiency of smart grid is presented. Finally, the challenges are suggested to facilitate the application of V2X technology to the enhancement of energy efficiency.
Keywords: vehicle energy efficiency; V2X; vehicle-to-everything; V2V; vehicle-to-vehicle; V2I; vehicle-to-infrastructure; V2N; vehicle-to-network; V2G; vehicle-to-grid.
The effect of peppermint odour on fatigue and vigilance in conditional automated vehicle
by Qiuyang Tang, Gang Guo, Mengjin Zeng
Abstract: Drivers in conditionally automated vehicles have been found to become fatigued easier than manual drivers, and the risk of accidents increased due to the decrease in vigilance. Olfactory stimulation is a promising method to counterbalance fatigue and increase vigilance. However, little is known about the effect of peppermint odour on relieving fatigue and increasing vigilance during automated driving. Therefore, to better understand the effect of peppermint odour stimulation during automated driving, a driving simulator study with 34 participants was conducted. Subjective and objective variables were compared between two conditions: with peppermint odour and placebo (air). The results of the study indicated that the fatigue levels of drivers decreased after the release of peppermint odour. The indicators of reaction time and ocular variables supported that the drivers` vigilance increased during the peppermint stimulation. In conclusion, peppermint odour has a positive effect on relieving fatigue and increasing vigilance.
Keywords: fatigue countermeasures; peppermint odour; driver vigilance; eye movement; conditionally automated driving; pupillary; sleepiness; driving simulator; aromatherapy.
Research on modelling and simulation of singlemode power split hybrid system
by Aihua Chu, Yinnan Yuan, Xiang Chen, Zhang Tong, Wenran Geng, Huijun Cheng
Abstract: Aiming at an optimised single-mode compound power split hybrid system, the main operating mode of the hybrid system and the torque control strategy were developed in this paper. LMS/AMESim was used to establish the plant model of the vehicle as well as the key components of the hybrid system, while the vehicle control model was established in Matlab/Simulink. In addition, the fuel economy of a certain SUV under the NEDC road spectrum was simulated by the co-simulation model, and the simulation results were compared with the experimental results on the auto chassis dynamometer. The results demonstrated that the established simulation model is an accurate reflection of the physical reality under different road spectrum conditions. Application of the model can greatly reduce the difficulty of control strategy design and improve the efficiency of vehicle development.
Keywords: HEV; hybrid electric vehicle; power-split system; CHS2800; co-simulation; vehicle controller model; AMESim; Matlab/Simulink; real road spectrum; fuel consumption.
Energy management optimal strategy of FCHEV based on the Radau Pseudospectral method
by Yanwei Liu, Yuzhong Chen, Zhenye Li, Kegang Zhao
Abstract: Energy management of the fuel cell hybrid electric vehicles (FCHEVs) is vital with respect to improving FCHEV's performance and durability. Radau Pseudospectral method (RPM)-based optimal control of energy management of FCHEV is proposed to optimise the fuel cell's lifetime by means of reducing its performance degradation. To utilise the RPM, both state and control variables are approximated by global interpolation polynomials, and differential equations of state variables are approximated by the derivatives of interpolation polynomials. Accordingly, the optimal control problem is transformed into nonlinear problem to be solved. The fuel cell's performance degradation is selected as objective function. The optimal results in NEDC show that battery with larger capacity is more beneficial than smaller one for reducing the fuel cell's performance degradation, with the total time of large load change of the fuel cell reducing. The RPM is also an effective way to optimise other objectives to energy management.
Keywords: energy management; fuel cell vehicle; electric vehicle; fuel cell degradation; hybrid power system; RPM; Radau Pseudospectral method; optimal strategy; optimal control; state of charge; hydrogen consumption.
Control strategy of genetic algorithm for a hybrid electric container loader
by Jian Li, Hong Shu, Zhien Xu, Weizhou Huang
Abstract: A genetic algorithm is applied to optimise the control parameters of a hybrid electric loader. Based on the optimal control parameters, a multidimensional response surface model for control parameters was established by a response surface method. The simulation shows that under multiple loads, battery temperatures and initial SOCs, the fuel saving of the hybrid loader is significant, the battery maintains the charge sustain or reaches within the optimal range, the battery temperature rise is kept within a reasonable range, and the battery charge and discharge rate is controlled within 1C. The fuel consumption of the hybrid electric loader is reduced by more than 20% compared with the traditional loader under the full load conditions. Compared with the original calculation model optimised by genetic algorithms and the dynamic programming, it was verified that the calculation accuracy and fuel saving significance of the response surface model for control parameters.
Keywords: HEVs; hybrid electric vehicles; control strategy; genetic algorithm; response surface; hybrid electric loader; container loader; energy management strategy; fuel consumption; simulation.
Special Issue on: Recent Advancements in Commercial Vehicle Roll Dynamics Studies
Active Trailer Braking Control for Car-Trailer Combination Based on Multi-objective Fuzzy Algorithm
by Pengwei Su, Xing Xu, Feng Wang, Bin Wang, Jie Mi
Abstract: In order to improve the braking stability and path following performance of trailer under steering and braking conditions, a differential braking control method is proposed. Considering the electromechanical coupling characteristic of electromagnetic brake, a 6-DOF car-trailer (CT) combination dynamics model is established. A hierarchical control frame is proposed, the upper controller determines the additional yaw moment based on multi-objective fuzzy (MOF) control algorithm with yaw rate and hinge angle as control objects. The lower braking force distribution controller is designed with the rules to determine left and right braking torque, the electromagnetic brake gets the corresponding current to realize differential brake. A joint simulating model with TruckSim and Simulink is built, the simulation results show that the control strategy proposed in this paper effectively improves the braking stability of trailer. Compared with no differential braking control, the yaw rate and lateral acceleration are reduced, the hinge angle is closer to the ideal target under MOF control. Finally, real CT test is put forward to verify the accuracy of the model and the effectiveness of the control strategy.
Keywords: car-trailer; differential braking; yaw rate; hinge angle; multi-objective fuzzy algorithm; braking force distribution controller.
Effect of Off-centered Loading on Roll Stability of Multi-trailer Trucks
by Yang Chen, Xiaohan Zheng, Zichen Zhang, Mehdi Ahmadian
Abstract: The effect of partial loading on the wheel tip-up and rollover stability of 28-ft A-double tractor-trailers that are logistically attractive to the U.S. package carriers is studied using TruckSim
Keywords: off-centered loading; 28-ft A-double; commercial vehicle; roll stability; rollover; tip-up; J-turn; load transfer ratio; critical rollover speed; static stability factor.
GA Tuned H Infinity Roll Acceleration Controller Based on Series Active Variable Geometry Suspension on Rough Roads
by Shayan Nazemi, Masoud Masih-Tehrani, Morteza Mollajafari
Abstract: In this paper, a type of vehicle variable-geometry suspension, named, Series Active Variable Geometry Suspension is used on a GT car under turning event with crosswind forces on random Rough Road classes D and C in order to keep control of the vehicle\'s Roll Angle and Roll Angle Acceleration to prevent the car from transferring too much force into the passengers and the car\'s suspension links, also, to keep the tires Road Holding and not to let them leave the ground and prevent rollover accidents. To do so, first, the vehicle goes under modelling. The vehicle\'s full car dynamics are modeled. A Genetic Algorithm H? control synthesis would be applied to the system which goal objective is to control the vehicle\'s roll angle acceleration motion. Then, the maneuver fit for the goals is designed, which is turning with the forward speed of 100 km/h and an additional crosswind with the speed of 150 km/h that produces a maximum lateral acceleration of 0.4 m/s which is transferred to the vehicle\'s model. After that, the simulation is thoroughly discussed, it will be shown that the roads are generated using ISO8608, and random road classes D and C are produced. For comparison purposes, a Genetic Algorithm PID controller is designed so that the performance of the H? control synthesis would be better judged. The H? control synthesis succeeded in improving the vehicle\'s roll angle and rollover index up to 85% and the vehicle\'s roll angle acceleration up to 13% in comparison with the PID controller.
Keywords: H? Controller; Series Active Variable Geometry Suspension; SAVGS; Genetic Algorithm; Full-Car Modelling; Rollover Control; Random Rough Road.
Roll stability enhancement in a full dynamic ground-tour vehicle model based on series active variable-geometry suspension
by Amin Najafi, Masoud Masih-Tehrani
Abstract: Today, given the importance of vehicle rollover event and the high number of accidents in this area, in this paper, an attempt is made in the field of rollover prevention of the ground tour (GT) road vehicle equipped with a series of active variable-geometry suspension (SAVGS) system using a PID, Fuzzy PID and LQR controller. Previous works have used mostly skyhook and PID controllers. In this paper, the choice of these three controllers to achieve two advantages are to be robust and optimal. The complex has been evaluated in several different ways, taking into account the specific road conditions. In the present study, unlike previous works, an attempt has been made to use a full-dynamic vehicle model. This choice will make the study more comprehensive and accurate than the dynamic behavior of the vehicle. This will be due to the simulation results approaching the actual test values. Basics of controller design are reducing vertical body acceleration and, more importantly, for lowering the vehicle roll angle and overall angular accelerations to increase vehicle roll stability. The main differences and innovations made in the control strategy, in addition to choosing type of the controllers, are emphasis on the resistance of the controllers and use of a combination of the control methods to achieve the desired result. To achieve these aims, modeling of the full vehicle's dynamic parameters along with considering the actual test conditions is highly required, which in the present work, most of the above are covered. In summary, this work, while improving the control purposes such as roll prevention over to the expected parameters of vehicle suspension, such as separating vibrations and ride comfort, reduces overall energy consumption by selecting type of the suspension used.
Keywords: series active variable-geometry suspension; roll stability; Fuzzy-PID controller; linear quadratic regulator controller.
A Light-Duty Truck Model for the Analysis of On-center Handling Characteristics
by Yupeng Duan, Yunqing Zhang, Yan Wang, Jiongli Zeng, Peijun Xu
Abstract: For commercial vehicles, on-center handling characteristics deeply influences the driving safety and drivers feeling about the vehicle, since it represents steering feel and vehicle response on the highway. This research focuses on the on-center handling performance of light-duty trucks. A vehicle model was built to conduct the simulation of the on-center handling test. The model consists of a power steering system, non-independent front/rear suspensions, the powertrain system, and a mounted cab. Nonlinear properties of the power steering system, the friction hysteretic characteristic in the steering system, suspension system with leaf springs and tires are considered so as to reflect the complicated on-center handling characteristics. We conducted constant radius cornering tests, return-release tests, and high speed weave tests on a target vehicle. By comparing the test and simulation results, adjustments were made to the model parameters to improve simulation accuracy. A number of variables were altered to show its influence on the steering feel and vehicle response. The results show that the tires lateral force characteristics strongly affect the vehicle response. Steering gear ratio, steering system clearance, and caster angle strongly affect the steering feel.
Keywords: Light-duty trucks; On-center handling; Dynamic model; Parameter sensitivity analysis.
Roll Dynamics of Long Combination Semi-Trailers with Steerable Axles
by Borna Moghaddam, Wei Huang, Luke Steiginga, Gordon Poole, Robin Chhabra
Abstract: An assessment of the dynamic performance of Long Combination Vehicles (LCV) with steerable axle systems on their trailers was undertaken by National Research Council Canada in order to facilitate the regulation of LCVs for wider use on Canadian roads. A base dry box van A-train LCV combination and four steered combinations are modeled using TruckSim, each outfitted with a different steerable axle mechanism on the trailer. TruckSims driver logic is augmented through an optimized controller in Simulink to more accurately capture the drivers decision-making in response to the LCV dynamics and the steering mechanisms. Anti-lock Braking System (ABS) and traction control mechanisms are added to compensate for the reduced stability caused by improving the maneuverability. The modeled LCVs are run through high-speed lane change and high-speed turn simulations, the primary maneuvers that enable assessment of the roll dynamics of the truck combinations. The five configurations are compared in terms of standard performance parameters: static roll threshold, Rearward Amplification (RWA), Load Transfer Ration (LTR) , high-speed off-tracking and transient off-tracking. This study demonstrates that all of the proposed mechanisms are able to satisfy standard stability requirements.
Keywords: long combination vehicles; trailer steerable axles; roll stability; standard performance measures.
Mathematical model for farm tractors towing single axle trailer rollover prediction
by Giorgio Previati, Gianpiero Mastinu, Massimiliano Gobbi
Abstract: The paper deals with the estimation of the rollover limit of farms tractorrntowing a single axle trailer. Rollover is studied by considering the static stability on sloped surfaces. The relatively simple model is derived to understand the rollover mechanism basic features. Rollover phenomenon is quite complex and different instabilities can arise. In particular, depending on the actual available friction, the system can slide along the slope before reaching the rollover condition. The presence of trailer brakes plays a non negligible role. Different steering angles of the trailer with respect to the tractor are investigated. The derived model can predict the (static) rollover or sliding limit of farm tractor-single axle trailer systems for any orientation with respect to the slope and any tractor/trailer relative angle.
Keywords: rollover; tractor and trailer system; longitudinal and lateralrnslope; analytical models.
Analytical and Experimental Investigation of Roll Stability of a Truck Towing a Special Purpose Trailer with no Suspension
by Luke Steiginga, Wei Huang, Gordon Poole
Abstract: The purpose of this study was to compare the roll stability of three truck and trailer combinations. The special-purpose trailer was of particular interest because it had no suspension system. Multibody dynamics models of the vehicles were built to simulate vehicle performance on high-speed turns and lane changes. Physical testing was undertaken at a test track in order to tune and validate the numerical models. Roll stability was assessed by comparing static roll threshold and load transfer ratio values. All of the vehicles were shown to meet performance standards on a smooth surface, but introduction of surface roughness was shown to significantly decrease the roll stability of the trailer due to the lack of suspension.
Keywords: multibody dynamics; simulation; roll dynamics; TruckSim; roughness index; truck and trailer; model validation; static roll threshold; load transfer ratio; suspensionless trailer; roll stability.