Four-wheel Steering Control Research Articles

Simulation Analysis Of Vehicle Four-Wheel Steering Control

In order to study the handling stability of four-wheel steering vehicle, the vehicle is simplified into a linear two-degree-of-freedom model. The fuzzy control technology is used to study the proportional feedforward + fuzzy feedback control strategy of four-wheel steering vehicle, and the fuzzy control toolbox in Matlab/Simulink is used to establish the four-wheel steering control system. The simulation results show that the fuzzy control can effectively improve the response of rear wheel steering, improve the maneuverability of the vehicle at low speed, reduce the turning radius, and improve the handling stability of the vehicle at high speed.

Research on automobile four-wheel steering control system based on yaw angular velocity and centroid cornering angle

In order to improve the handling stability of four-wheel steering (4WS) cars, a two-degree-of-freedom 4WS vehicle dynamics model is constructed here, and the motion differential equation of the system model is established. Based on the quadratic optimal control theory, the optimal control of 4WS system is proposed in this paper. When running at low speed and high speed, through yaw rate feedback control, state feedback control, and optimal control, the 4WS cars are controlled based on yaw rate and centroid cornering angle with MATLAB/Simulink simulation. The result indicates that 4WS control based on the optimal control can improve the displacement of the cars. And, the optimal control of 4WS proposed in this paper can eliminate centroid cornering angle completely compared with other two traditional optimal control methods. Besides, the optimal control enjoys faster response speed and no overshoot happens. In conclusion, the optimal control method proposed in the paper represents better stability, moving track and stability, thereby further enhancing the handling property of cars.

Design and test of flexible chassis automatic tracking steering system

In order to develop an innovative omnidirectional non-homonymic flexible chassis (FC), the four-wheel steering control method of FC was designed by a new concept called off-centered steering (OCS) and the automatic tracking steering system was analyzed. Novelty of this wheel concept lies in the non-conventional positioning of the steering axis and wheel axis. Additionally, the steering axis of steerable wheel was motorized with an on/off electrometrical brake to overcome a hyper-motorization issue inherent to the wheel’s geometrical properties and hold the steering position. Based on the off-centered steering characteristics of FC, the Wheatstone bridge was applied in the steering control system. The bridge resistances are used to track target steering angles and the actual steering angle, respectively. The output voltage of the bridge is exploited to adjust the wheel’s speed so that steering and automatic tracking could be achieved. Experiments at different speeds, loadings, and target steering angles were conducted. Results showed that the chassis can indeed be controlled independently and its steering range is from –90° to 90°, which indicated the automatic tracking steering system was effective. The electromagnetic lock (EL) can significantly improve the stability of the chassis and reduce the vibration. Loading has no significant effect on the accuracy of the steering angle and the time it takes to complete steering tasks. The time taken to complete a forward steering task showed a linear relationship with the required angles, but was independent of rotation speed; for backward steering, time was related to both target angles and rotation speed. The results presented in this research may provide a reference for the steering control strategies of the four-wheel individual drive and four-wheel (4WID/4WIS) vehicle in the future. Keywords: electric vehicles, flexible chassis, four-wheel steering, automatic tracking, control system DOI: 10.25165/j.ijabe.20171005.2525 Citation: Song S J, Li Y N, Qu J W, Zhou W, Guo K Q. Design and test of flexible chassis automatic tracking steering system. Int J Agric & Biol Eng, 2017; 10(5): 45–54.

An integrated algorithm for vehicle stability improvement with the coordination of direct yaw moment and four-wheel steering control

This paper presents an integrated algorithm for enhancing vehicle stability with the coordination of four-wheel steering and direct yaw moment control based on a hierarchical control structure. At the upper level of the integrated control system, the desired four-wheel steering angles and yaw moment are derived using a sliding mode control technique; at the lower level, the control inputs are optimised and implemented using a pseudo-inverse method. A 2 degrees of freedom (DOF) vehicle model is generated to design the integrated control algorithm, and an 8-DOF non-linear vehicle model is developed for numerical simulations. The algorithm is evaluated using a hardware-in-the-loop real-time simulation system (HILS) with the physical implementation of active four-wheel steering and differential braking. It is demonstrated that the proposed algorithm can enhance vehicle handling and stability under different operating conditions.

Design and test of flexible chassis automatic tracking steering system

In order to develop an innovative omnidirectional non-homonymic flexible chassis (FC), the four-wheel steering control method of FC was designed by a new concept called off-centered steering (OCS) and the automatic tracking steering system was analyzed. Novelty of this wheel concept lies in the non-conventional positioning of the steering axis and wheel axis. Additionally, the steering axis of steerable wheel was motorized with an on/off electrometrical brake to overcome a hyper-motorization issue inherent to the wheel’s geometrical properties and hold the steering position. Based on the off-centered steering characteristics of FC, the Wheatstone bridge was applied in the steering control system. The bridge resistances are used to track target steering angles and the actual steering angle, respectively. The output voltage of the bridge is exploited to adjust the wheel’s speed so that steering and automatic tracking could be achieved. Experiments at different speeds, loadings, and target steering angles were conducted. Results showed that the chassis can indeed be controlled independently and its steering range is from –90° to 90°, which indicated the automatic tracking steering system was effective. The electromagnetic lock (EL) can significantly improve the stability of the chassis and reduce the vibration. Loading has no significant effect on the accuracy of the steering angle and the time it takes to complete steering tasks. The time taken to complete a forward steering task showed a linear relationship with the required angles, but was independent of rotation speed; for backward steering, time was related to both target angles and rotation speed. The results presented in this research may provide a reference for the steering control strategies of the four-wheel individual drive and four-wheel (4WID/4WIS) vehicle in the future. Keywords: electric vehicles, flexible chassis, four-wheel steering, automatic tracking, control system DOI: 10.25165/j.ijabe.20171005.2525 Citation: Song S J, Li Y N, Qu J W, Zhou W, Guo K Q. Design and test of flexible chassis automatic tracking steering system. Int J Agric & Biol Eng, 2017; 10(5): 45–54.

Evaluation of chassis control method through optimisation-based controllability region computation

This paper proposes a new systematic evaluation approach for vehicle maneuverability based on controllability region computations. In this approach, the controllability region, defined as the set of vehicle initial states that can be transferred to a stable equilibrium point in the state space by using allowable controls, is calculated. The size of the controllability region for an open-loop system can serve as a measure of the intrinsic performance of the control method, because if the vehicle state is displaced outside of the controllability region, no controller will be able to maintain vehicle stability. The problem of determining the controllability region boundary is formulated as an optimisation problem such that the controls maximising the norm of the initial state can be determined. Thereby, the performances of four-wheel steering control and direct yaw moment control are evaluated and compared by the proposed procedure.

Study on Vehicle Stability Control Based on Yaw Following and 4WS

Because of the high speed and insufficient stopping distance, a sudden obstacle will force the vehicle to perform a lane change maneuver to avoid a crash or rear-end collision. A vehicle yaw following control system was designed in this paper to prevent vehicles from spinning and drifting out on high speed obstacle avoidance under emergency. However, yaw following control system, in some situation, may not react properly to, or even deteriorate on-road rollover events. Four-wheel steering control system can reduce the excessive yaw movement due to yaw following control system. An integration control system, including yaw following control system and four-wheel steering control system was presented and discussed. With this improved control system, the vehicle lateral stability can be improved on high speed obstacle avoidance.

A Study on μ-Synthesis Control for Four-Wheel Steering System to Enhance Vehicle Lateral Stability

This paper presents the design of μ-synthesis control for four-wheel steering (4WS) vehicle and an experimental study using a hardware-in-the-loop (Hil) setup. First, the robust controller is designed and the selection of weighting functions is discussed in the framework of μ-synthesis control scheme, considering the varying parameters induced by running vehicle condition. Second, in order to investigate the feasibility of the four-wheel steering control system, the 4WS vehicle control system is built using dSPACE DS1005 platform. The experimental tests are performed using the Hil setup which has been constructed using the devised rear steering actuating system. The dynamics performance is evaluated by experiment using the Hil setup under the condition of parameter variations. Finally, experimental results show that the μ-synthesis controller can enhance good vehicle lateral maneuverability.

スライディングモード制御を用いた四輪操舵制御における非線形ゲインの調整法

スライディングモード制御を用いた四輪操舵制御における非線形ゲインの調整法

Four wheel steering control by fuzzy approach

This study introduces a fuzzy four-wheel steering control design method for automotive vehicles. After the analysis of some stability aspects of the vehicle lateral motion, including front steering angle variations, the representation of vehicle nonlinear model by Takagi-Sugeno (T-S) fuzzy model is presented. Next, based on the fuzzy model, a fuzzy controller is developed to improve the stability of the vehicle. Sufficient conditions for stability and stabilization of the T-S fuzzy model using fuzzy feedback controllers is given. To demonstrate the effectiveness of the proposed fuzzy controller, simulation results are given showing the performance improvements of the vehicle in terms of the stability and the maneuverability in critical situations.

The performance of a vehicle with four-wheel steering control in crosswind

A nonlinear 5 degrees of freedom (DOF) system is used to model the dynamics of a four-wheel steering control vehicle. In the model the yawing and roll motions of the sprung mass of the vehicle are considered and the nonlinear differential equations of motion are derived. In addition, the crosswind model and the driver model are established in this paper. They are used to investigate both the conventional front-wheel steering (FWS) and the four-wheel steering (4WS) vehicle during a crosswind disturbance. Two different 4WS control laws are used. The first is an open loop control law (OL4) in which the rear wheel steering angle is only determined by the front wheel steering angle. The second is a closed loop law (CL4) in which the rear wheel angle is determined by both the front wheel steering angle and the yawing angle of the sprung mass of the vehicle. Simulation results indicate that the CL4 system significantly improves the vehicle steering stability in response to a crosswind disturbance.