International Journal of Vehicle Design (17 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.
Modal analysis and structure optimisation of vehicle seat frame based on mass distribution method
by Zheng Zhang, Dong Ye, Congda Lu, Feng Li, Yi Huang, Huaping Wu, Shaofei Jiang
Abstract: The vehicle seat is not only one of the important parts of vehicle interiors, but also the main component that connects occupants and the car body directly. The vibration characteristics of the vehicle seat severely affect the security and dynamic comfort of drivers/passengers. For this reason, the design and optimisation of the vehicle seat have been become increasingly necessary and attractive. A vehicle seat frame developed in the cooperative company is selected as the research object in this paper. The mode of vehicle seat frame is compared by experimental modal test and finite element analysis in order to verify the correctness of the finite element model of vehicle seat. Then, the influence of mass distribution on the vehicle seat frame modal characteristics is investigated by changing the local mass distribution of the vehicle seat through finite element modelling. By optimising the structure of the vehicle seat frame based on the analysis results, the dynamic characteristics of vehicle seat can be improved and the security and dynamic comfort can be enhanced.
Keywords: vehicle seat; experimental modal test; finite element analysis; mass distribution; structure optimisation.
Preliminary evaluation research of a powertrain system with electrically controlled planetary gear
by A. Lechowicz, Andrzej Augustynowicz
Abstract: This paper presents a concept of a simple hybrid system intended for use in a light vehicle. The basic element of the proposed system is an electrically controlled planetary gear, which combines input from a combustion engine and an electric motor. The transmissions combine the power from two sources, a gasoline engine and an electric motor. The proposed hybrid solution is characterised by a simple construction that allows its use in small vehicles. This solution can maximise the performance of combustion engine.
Keywords: energy management; hybrid system; hybrid vehicle powertrain configurations.
Lateral stability control of vehicles based on the calculation and allocation of component forces
by Guang Xia, Xiwen Tang, Yangying Hua, Wuwei Chen
Abstract: A vehicle lateral stability control method for real-time calculation and dynamic allocation of the longitudinal force and yaw moment of vehicle tyres is proposed. The achievable range of the longitudinal force and yaw moment of the tyre are calculated in real time through off-line numerical optimisation and nonlinear programming. The calculated values are then adjusted to within the available range and allocated dynamically. A controller for the slip rate and front wheel slip angle is used to ensure that the tyre friction can trace each component force. The proposed method avoids estimating the lateral force of vehicle rear wheels while ensuring accuracy. The results of simulations and driver-in-loop tests demonstrated that the proposed method can improve the track-holding ability while reducing the influence of a road surface with a low adhesion coefficient on vehicle stability. The method ensures high and dynamic tracking performance and lateral stability.
Keywords: longitudinal force component; yaw torque; calculation and allocation of component forces; lateral stability control.
The vehicle frontal impact safety evaluation and design method based on the coupling effect between crash pulse and restraint system characteristic
by Junyuan Zhang, Danqi Wang, Yang Jin, Linan Wu, Hao Zhou
Abstract: The coupling effect analysis between crash pulse and restraint system characteristics has a great significance to guide structural design and restraint system matching in the safety design of vehicles. This paper presents a new method to evaluate and design stiffness of vehicle structure and restraint system from the perspective of coupling effect, at the preliminary stage of safety design. The equivalent dual-trapezia wave (EDTW) and three-segment stiffness curve (TSSC) are defined as the stiffness of the vehicle structure and the restraint system, respectively. The fast iteration algorithm is established by a simple occupantvehicle model to calculate occupant response database. According to the database analysis, the expressions about three indexes, which can evaluate the crash pulse, restraint system and the coupling effect between them, are derived by the parameters of EDTW and TSSC. Based on the data from NHTSA frontal crash impact tests, the star-estimate map is established to estimate the star rating and achieve the design of EDTW and TSSC. Finally, a safety design example of M6 model is optimised to verify the validity of the proposed method. The results show that the relative risk score of the designed solution decreases by 43.6%. The proposed method can be used in the phase of conceptual design, greatly reducing the calculation amount of CAE analysis and shortening the product development cycle.
Keywords: vehicle impact; coupling; evaluation; equivalent dual-trapezia wave; three-segment stiffness curve.
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.
Finite element analysis of thermal buckling characteristics of automotive 430 dry clutch pressure plate
by Yubing Gong, Wencheng Ge, Yun-Bo Yi
Abstract: The thermal buckling analysis of the automotive dry clutch pressure plate is performed by the finite element method based on the thermal buckling theory. According to the temperature distribution of the pressure plate under the realistic conditions, two typical thermal loads are assumed and applied in the thermal buckling analysis of the pressure plate. The thermal buckling characteristics of the pressure plate, including critical temperature and buckling mode under these two typical thermal loads, are comprehensively investigated. The influence of the temperature distribution along the pressure plate thickness direction on the thermal buckling characteristics of the pressure plate is analysed. The effect of boundary constraints on the thermal buckling modes is further studied. The analysis results show that (1) the temperature distribution on the thickness of the pressure plate has a negligible effect on its thermal buckling characteristics; (2) the boundary condition of the pressure plate has a significant effect on the thermal buckling mode of the pressure plate; and (3) the thermal buckling of the pressure plate occurs more readily in its cooling stage than in the heating stage. Since the critical buckling temperature far exceeds the actual possible temperature of the pressure plate, the thermal buckling in the pressure plate will probably not occur in actual applications. Therefore it is concluded that the concave deformation of automobile dry clutch pressure plate is not induced by the thermal buckling mechanism.
Keywords: automotive dry clutch; temperature distribution; buckling mode; pressure plate；boundary constraints; thermal buckling；critical buckling temperature; finite element method；concave deformation.
Attitude motion control of a vehicle including the active passenger seat system
by Wu Liang, Muhammad Arshad Khan, Edward Youn, Iljoong Youn, Masayoshi Tomizuka
Abstract: This research focuses on improving the attitude motion of a vehicle using active suspension and active seat together. The proposed attitude-tracking controller eliminates the unpleasant lateral and longitudinal forces acting on passengers by tilting the vehicle against the direction of the centrifugal forces created in cornering, braking, and accelerating. In addition to the enhancement of ride comfort, better road-holding capability is also achieved by evenly distributing forces on all wheels. An active seat system is added to the car body in order to accommodate angles larger than the available body angle. A nonlinear model is used to simulate the performance that more resembles the actual system, and the difference between linear and nonlinear models is analysed by comparing the simulation. The simulation results show that using an active passenger seat with the attitude-tracking controller can improve ride comfort more than using attitude-tracking controller alone.
Keywords: attitude motion control; tracking control; ride comfort; handling capability; nonlinear model; active passenger seat.
Representation of intended user experiences of a vehicle in early design stages
by Alexandre Gentner, Carole Bouchard, Carole Favart
Abstract: This research explores cross-functional design information exchange during the early phases of vehicle development projects and discusses the underlying notion of functional walls hindering interactions between design team members with different backgrounds. After an initial description of the state of the art, this article details an experimental phase composed of three stages. The first research stage collected and clustered descriptions of real-life user experiences. These clusters were used as a starting point for the selection of user experience intentions related to a future vehicle and for the creation of multi-sensory early representations (second stage). The generated representations cover a wide spectrum of user experience-related design information: characteristics of targeted users, intended perceived semantics and emotions, as well as attributes of the to-be-designed vehicle. Different versions of these representations were then assessed by automotive professionals in order to understand the influence of the layout on the understanding of design information and subjective perception criteria (third stage). The results obtained show that multi-sensory layouts tend to be better understood and more appreciated. Their contribution to the opening of functional walls existing within design teams is then argued. Finally, the representations created and assessed during the experimental phase permit to discuss the nature of design information that can be conveyed by preliminary representations and to compare it with models identified as the state of the art.
Keywords: vehicle design; car design; new concept development; pre-development; user experience; kansei design; intermediate representation; design information; industrial context.
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 tire 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.
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.