This paper presents a disturbance observer based control strategy for four wheel steering systems in order to improve vehicle handling stability. By combination of feedforward control and feedback control, the front a...This paper presents a disturbance observer based control strategy for four wheel steering systems in order to improve vehicle handling stability. By combination of feedforward control and feedback control, the front and rear wheel steering angles are controlled simultaneously to follow both the desired sideslip angle and the yaw rate of the reference vehicle model.A nonlinear three degree-of-freedom four wheel steering vehicle model containing lateral, yaw and roll motions is built up, which also takes the dynamic effects of crosswind into consideration.The disturbance observer based control method is provided to cope with ignored nonlinear dynamics and to handle exogenous disturbances. Finally, a simulation experiment is carried out,which shows that the proposed four wheel steering vehicle can guarantee handling stability and present strong robustness against external disturbances.展开更多
An active front steering （AFS） intervention control during braking for vehicle stability is presented. Based on the investigation of AFS mechanism, a simplified model of steering system is established and integrated...An active front steering （AFS） intervention control during braking for vehicle stability is presented. Based on the investigation of AFS mechanism, a simplified model of steering system is established and integrated with vehicle model. Then the AFS control on vehicle handling dynamics during braking is designed. Due to the difficulties associated with the sideslip angle measurement of vehicle, a state observer is designed to provide real time estimation. Thereafter, the controller with the feedback of both sideslip and yaw angle is implemented. To evaluate the system control, the proposed AFS controlled vehicle has been tested in the Hardware-in-the-loop-simulation （HILS） system and compared with that of conventional vehicle. Results show that AFS can improve vehicle lateral stability effectively without reducing the braking performance.展开更多
The steering characteristic of a four-wheel-steering vehicle is numerically simulated for in-depth research of the handling stability of four-wheel steering. The research results show that the deteriorating tendency o...The steering characteristic of a four-wheel-steering vehicle is numerically simulated for in-depth research of the handling stability of four-wheel steering. The research results show that the deteriorating tendency of the steering stability due to the increase of the vehicle speed is improved obviously in the case of four-wheel steering. The approach of variable steering ratio is discussed. The use of the variable steering ratio can not only raise the steering stability of vechicles at high vehicle speed, but also reduce the dicomfort and steering burden of drivers; and hence is helpful for the subjective evaluation of four-wheel steering vehicles.展开更多
The revolution of physical structure is highly significant for future software defined vehicles(SDV).Active structural transformation is a promising feature of the next generation of vehicle physical structure.It can ...The revolution of physical structure is highly significant for future software defined vehicles(SDV).Active structural transformation is a promising feature of the next generation of vehicle physical structure.It can enhance the dynamic performance of vehicles,thus providing safer and more comfortable ride experiences,such as the ability to avoid rollover in critical situations.Based on the active structural transformation technology,this study proposes a novel approach to improve the dynamic performance of a vehicle.The first analytical motion model of a vehicle with active structural transformation capability is established.Then,a multi-objective optimization problem with the adjustable parameters as design variables is abstracted and solved with an innovative scenario specific optimization method.Simulation results under different driving scenarios revealed that the active transformable vehicle applying the proposed method could significantly improve the handling stability without sacrificing the ride comfort,compared with a conventional vehicle with a fixed structure.The proposed method pipeline is defined by the software and supported by the hardware.It fully embodies the characteristics of SDV,and inspires the improvement of multiple types of vehicle performance based on the concept of“being defined by software”and the revolution of the physical structure.展开更多
Four wheel steering(4 WS) technology can effectively improve the vehicle handling stability and driving safety. In order to fully consider the influence of the rear wheel steering, the vehicle dynamics model of 4 WS v...Four wheel steering(4 WS) technology can effectively improve the vehicle handling stability and driving safety. In order to fully consider the influence of the rear wheel steering, the vehicle dynamics model of 4 WS vehicle, including the rear wheel steering by wire and two degrees of freedom vehicle model of 4 WS vehicle, is established in this paper. The desired yaw rate is obtained according to the variable transmission ratio strategy. The yaw rate tracking strategy is applied to 4 WS vehicle and rear wheel steering resistance moment is taken into account. Based on the robust control theory, H_2/H_∞ mixed robust controller design is carried to research the stability control of 4 WS vehicle. Finally, the closed-loop simulation added driver model based on preview theory is carried out. The simulation results indicate that the designed H_2/H_∞ mixed robust controller can achieve the stability control.展开更多
基金supported by the National Natural Science Foundation of China(61573165,61520106008,61703178)
文摘This paper presents a disturbance observer based control strategy for four wheel steering systems in order to improve vehicle handling stability. By combination of feedforward control and feedback control, the front and rear wheel steering angles are controlled simultaneously to follow both the desired sideslip angle and the yaw rate of the reference vehicle model.A nonlinear three degree-of-freedom four wheel steering vehicle model containing lateral, yaw and roll motions is built up, which also takes the dynamic effects of crosswind into consideration.The disturbance observer based control method is provided to cope with ignored nonlinear dynamics and to handle exogenous disturbances. Finally, a simulation experiment is carried out,which shows that the proposed four wheel steering vehicle can guarantee handling stability and present strong robustness against external disturbances.
文摘An active front steering （AFS） intervention control during braking for vehicle stability is presented. Based on the investigation of AFS mechanism, a simplified model of steering system is established and integrated with vehicle model. Then the AFS control on vehicle handling dynamics during braking is designed. Due to the difficulties associated with the sideslip angle measurement of vehicle, a state observer is designed to provide real time estimation. Thereafter, the controller with the feedback of both sideslip and yaw angle is implemented. To evaluate the system control, the proposed AFS controlled vehicle has been tested in the Hardware-in-the-loop-simulation （HILS） system and compared with that of conventional vehicle. Results show that AFS can improve vehicle lateral stability effectively without reducing the braking performance.
文摘The steering characteristic of a four-wheel-steering vehicle is numerically simulated for in-depth research of the handling stability of four-wheel steering. The research results show that the deteriorating tendency of the steering stability due to the increase of the vehicle speed is improved obviously in the case of four-wheel steering. The approach of variable steering ratio is discussed. The use of the variable steering ratio can not only raise the steering stability of vechicles at high vehicle speed, but also reduce the dicomfort and steering burden of drivers; and hence is helpful for the subjective evaluation of four-wheel steering vehicles.
基金sponsored in part by the NSFC Program(61872217,U20A20285,52122217,52221005,U1801263)in part by the National Key R&D Program of China(2020YFB1710901,2018YFB1308601)in part by the Jiangxi Provincial Natural Science Foundation under Grant 20224ACB218002.
文摘The revolution of physical structure is highly significant for future software defined vehicles(SDV).Active structural transformation is a promising feature of the next generation of vehicle physical structure.It can enhance the dynamic performance of vehicles,thus providing safer and more comfortable ride experiences,such as the ability to avoid rollover in critical situations.Based on the active structural transformation technology,this study proposes a novel approach to improve the dynamic performance of a vehicle.The first analytical motion model of a vehicle with active structural transformation capability is established.Then,a multi-objective optimization problem with the adjustable parameters as design variables is abstracted and solved with an innovative scenario specific optimization method.Simulation results under different driving scenarios revealed that the active transformable vehicle applying the proposed method could significantly improve the handling stability without sacrificing the ride comfort,compared with a conventional vehicle with a fixed structure.The proposed method pipeline is defined by the software and supported by the hardware.It fully embodies the characteristics of SDV,and inspires the improvement of multiple types of vehicle performance based on the concept of“being defined by software”and the revolution of the physical structure.
基金supported by the National Natural Science Foundation of China(Grant No.51375007)the Fundamental Research Funds for the Central Universities(Grant No.NE2016002)Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems(Grant No.GZKF-201605)
文摘Four wheel steering(4 WS) technology can effectively improve the vehicle handling stability and driving safety. In order to fully consider the influence of the rear wheel steering, the vehicle dynamics model of 4 WS vehicle, including the rear wheel steering by wire and two degrees of freedom vehicle model of 4 WS vehicle, is established in this paper. The desired yaw rate is obtained according to the variable transmission ratio strategy. The yaw rate tracking strategy is applied to 4 WS vehicle and rear wheel steering resistance moment is taken into account. Based on the robust control theory, H_2/H_∞ mixed robust controller design is carried to research the stability control of 4 WS vehicle. Finally, the closed-loop simulation added driver model based on preview theory is carried out. The simulation results indicate that the designed H_2/H_∞ mixed robust controller can achieve the stability control.
