International Journal of Vehicle Design (13 papers in press)
Modelling, validation and characterisation of high-performance suspensions by means of a suspension test rig
by Christoph Zauner, Johannes Edelmann, Manfred Plochl
Abstract: To meet the high demands and expectations on ride comfort and handling, detailed analysis of the vibrational behaviour of advanced suspension systems is required. Therefore, component modelling and testing, as well as full vehicle tests, go hand in hand. The present study addresses possible benefits, when a suspension test rig is available, and how it may be used to better analyse and characterise the vibrational behaviour of particular isolated suspensions. Respective synthetic excitation spectra map the dynamic behaviour of the suspension from full vehicle tests to the suspension test rig. Component models are presented that show a reasonable compromise between modelling and parametrisation effort. By using the suspension test rig it is revealed that frictional effects must be considered when assembling the components of a full suspension model. Two high-performance suspensions have been chosen to propose appropriate analysis methods of their vibrational behaviour. In this way, insight into the modal behaviour is revealed, and vibrational characteristics, which can directly be assigned to the respective suspension, become obvious, which may allow comparison with follow-up similar suspensions. Finally, the suspension models are evaluated with full vehicle tests.
Keywords: suspension characterisation; suspension test rig; ride comfort; vibration analysis; double wishbone suspension; multi-link suspension.
High dimensional expression of combined approximation model
by Weiping Li, Bei Gu
Abstract: In this paper, a new high dimensional model representation (HDMR), combining TPS, SVR and Kriging (TSK) by weighted combination method based on generalised mean square error (GMSE) is proposed, called TSK-HDMR. TSK-HDMR could not only take advantage of the robustness of the combined approximation model but also reveal the correlation relationships among input variables. The model and the algorithm fundamentally change the exponentially growing computation cost to be polynomial. Numerical examples are given to verify the robustness and modelling efficiency of the modelling method. Compared with the classical high-dimension model techniques, in the application of the modelling of air resistance characteristic of a car, the efficiency and accuracy are improved.
Keywords: GMSE; combined approximation model; robustness; air resistance characteristic of car.
Vehicle parameters identification with particle swarm optimization for four-wheel independent motor-drive vehicle
by Hongliang Zhou, Zhiyuan Liu, Xingwang Yang, Levent Guvenc
Abstract: An identification method for vehicle dynamics parameters that is based on particle swarm optimisation (PSO) is presented in this paper using a four-wheel independent motor-drive (FWIM) vehicle in the tests. The parameters that are identified are vehicle body mass, yaw moment of inertia, position of centre of gravity, rotational inertia of wheels, tyre stiffness coefficients and some coupling parameters. The identification process consists of two steps. In the first step, wheel rotational inertias are identified using test data of motor torque and wheel speed. In the second step, a nonlinear vehicle dynamics model with vehicle longitudinal and lateral dynamics, wheel dynamics model and tyre characteristics, and the parameters related to vehicle body and the tyre, are identified with the test data of motor torque, accelerations, yaw rate and wheel speeds. The model outputs and test data are compared and the parameters seem to be very accurate. A benchmarking study using a commercially available optimisation routine for the same parameter identification task is carried out, and the PSO method presented here is observed to be much more accurate.
Keywords: parameter identification; particle swarm optimisation; four-wheel independent motor-drive vehicle.
Research on the real-time identification approach of longitudinal road slope and maximum road friction coefficient
by Wenliang Yong, Bo Wang, Minghui Ding
Abstract: Real-time knowledge of maximum road friction coefficient and road slope angle is crucial for active vehicle control systems. Most recent researches on road slope identification mainly assume that the road slope is constant. It is hard to identify the road slope accurately under complex slope conditions, and the influence of the road slope on the identification of the maximum road friction coefficient is not considered. In this paper, the interacting multiple model Kalman filter method for the identification of road longitudinal slope is proposed, based on existing sensors. Then the current road type is recognised by comparing the samples of the estimated instantaneous road friction coefficient with the standard values of each typical road, using the principle of minimum standard deviation, and the influence of the road slope on the axle load transfer is considered. Once the road type is recognised, the maximum road friction coefficient can be easily determined by an online lookup table. Finally, experimental tests on the braking system hardware-in-the-loop test rig driven by the driving simulator are conducted. The results demonstrate that the identification approach can identify the current road slope and maximum road friction coefficient with good adaptability to various vehicle conditions.
Keywords: identification; maximum road friction coefficient; road slope; IMM Kalman filter; road type recognition.
European high-Speed bogie technology review
by Huailong Shi, Xiaojun Deng, Haiyun Zhu
Abstract: This review presents the current technical status of European high-speed bogie technology and related infrastructure, in which the concepts and design solutions associated with the high-speed rolling stocks and railway are summarised. Regarding the high-speed railway infrastructure conditions, the vehicle gauges, track gauge, rail profiles, and associated inclinations for various countries and rail networks are discussed briefly, as well as the curve arrangements and track irregularities. Then four typical and widely used high-speed bogies are introduced, and their design principles and solutions are discussed, in which the advantages and disadvantages of various bogie frame types, bearings, wheelset steering arrangements, and primary/secondary suspensions are thoroughly analysed. Furthermore, the brake system commonly used in European railway networks and the on-board diagnostic systems used to ensure safe operation are also discussed concerning their applicability, versatility and reliability. A general understanding of the technical specification for interoperability is also included in this investigation.
Keywords: high-speed railway; infrastructure; vehicle gauge; track gauge; technical specification for interoperability.
Design of robust output-feedback-based automatic steering controller for unmanned electric vehicles
by Keqiang Li, Jinghua Guo, Yugong Luo
Abstract: This paper presents a robust output-feedback-based automatic steering control scheme for unmanned electric vehicles (UEV). To address the challenging problem, an uncertain dynamic model of the UEV is firstly developed, in which the uncertainties in the tyre cornering stiffness and the actuator faults are included. Then, to deal with the uncertain features and actuator faults of UEV, a robust output-feedback-based control algorithm for automatic steering system of UEV is proposed to achieve the prescribed transient for path tracking errors while keeping all other closed-loop signals bounded. Finally, simulation and experimental results demonstrate that the proposed automatic steering control scheme can effectively improve the tracking performance of UEV.
Keywords: automatic steering controller; unmanned electric vehicles; actuator faults; robust control; uncertainties.
Research on transfer case transmission power of heat load Characteristics
by Yu-ming Wang, Qi-dong Wang, Li-qing Chen, Tian-yi Gu
Abstract: As one of the essential components of smart four-wheel drive, the multi-plate clutch has been studied thoroughly in the area of mechanical drive in the past. However, its friction heat during the transmission of power is rarely discussed. In our work, we construct a model of the multi-plate clutch based on heat load characteristics. We then build a performance simulation model in Matlab/Simulink to analyse the influence of the structural dimensions of the friction disc, the material properties of the friction disc and the working conditions of the friction disc on the dynamic transfer characteristics, and through the construction of a multi plate clutch test platform, the variation of the total torque and torque response time passed by the shunt is basically consistent with the simulation value. Then the thermal load characteristics of the multi-plate clutch are analysed. The result shows that the heat load has a great influence on the friction coefficient and the viscosity of the lubricating oil. The peak viscous torque is one-third of the peak total torque, and it costs about 0.3 seconds to reach the peak total torque. The number of friction plates and the pressure play major roles to determine transferable torque. The widths of sumps, while affecting the viscous torque greatly, do not affect asperity torque as much. We analyse the difference between transferable torques of multi-plate clutches with and without trenches under heat load, and find the important role of heat load in the working process of multi-plate clutches. We also find how its operating characteristic varies during the connecting process, which can provide a theoretical basis for the designing of multi-plate clutches.
Keywords: transfer case; multi-plate clutch; power transfer; thermal load; experimental test.
Switched anti-roll control design for hydraulically interconnected suspension system with time delay
by Xiaojian Wu, Bing Zhou, Juhua Huang, Xiang Qiu
Abstract: To improve a vehicle's anti-roll performance while consuming less energy, an active/passive dual-mode switched control method based on a hydraulically interconnected suspension (HIS) is proposed. This method has two key components as follows: modelling the "mechanical-liquid-gas" coupled dynamic system consisting of hydraulic cylinders, a hydraulic pump and accumulators; and robustly controlling a time-delayed system with uncertain model and lag time. In this study, the nonlinear characteristics of the underlying HIS system's execution were considered, and a 4 degree-of-freedom (DOF) roll-plane half-car model was employed for the study. The backstepping nonlinear algorithm was adopted to maintain the body in the desired posture. Subsequently, a modified Smith predictor and a Taylor expansion of lateral acceleration were applied to compensate for the time delay caused by the hydraulic transmission and the hydraulic pump fluid pressure increase, respectively. Finally, a double-lane change simulation with uncertain parameters and lag time was performed. The results indicate that the proposed method is robust in the case of an uncertain control system and can effectively improve the vehicle's anti-roll performance.
Keywords: anti-roll; hydraulically interconnected suspension; switched control; time delay; nonlinear dynamics.
Ergonomic intervention in meeting the challenges of elderly drivers: identifying, prioritising and factorising the ergonomic attributes
by Ashish Dutta, A.K. Bhardwaj, A. P. S. Rathore
Abstract: Better life expectancy has caused a demographic shift worldwide and has led to a considerable rise in the proportion of the seniors, aged above 65. The number of elderly drivers has also increased, who, even with physiological limitations, do not want to give up driving. This has necessitated conscious efforts to be made during the car design stage, to analyse their ergonomic needs and challenges. This research was aimed to identify the major ergonomic concern of the aged drivers that will improve their posture, increase attention and decrease fatigue during driving. Their needs were grouped into ten ergonomic attributes and their opinions about each attribute was captured from a consumer survey. Attributes were prioritised and factor analysis was carried out. Three factors were extracted and were named as musculoskeletal factor, safety factor, and man-machine interface factor. This research provides an understanding of the ergonomic needs of senior drivers, which car manufacturers and automobile designers may consider during the design phase to make a car ergonomically more compatible.
Keywords: automobile design and development; car ergonomics; challenges of elders; elder drivers; ergonomic attributes; factor analysis; factorising attributes; participatory ergonomics; prioritising attributes; vehicle design.
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.