The Design And Simulation Of Fuzzy Control For Four Wheel Steering Vehicle Based On ADAMS

Four Wheel Steering (4WS) technology is rapidly developing along with users’ requirements of vehicle agility in low speed and better handling and stability in high speed. 4WS vehicle has an additional rear wheel steering system besides traditional front wheel steering when compared with traditional vehicles. The key technology of 4WS is the development of control strategy. Nowadays, it is one of research focuses in vehicle engineering. Fuzzy control is one of the hot topics in modern control field. Fuzzy control can simulate human cognition and experience. This makes it can be applied to engineering. Therefore, applying fuzzy control and its advantages into the development of the control strategy for 4WS is important and significant in vehicle engineering.Firstly, a 2 Dofs vehicle handling model is built to analyze vehicle characteristics of 4WS with the aim of zero vehicle side slip angle. In the simulation, front feedback control strategy is applied to ensure the aim of zero vehicle side slip angle in the paper. Then,4WS and 2WS vehicles under different speeds are simulated to show the ability of the purposed front feedback control strategy. The simulation results shows that zero vehicle side slip angle front feedback control strategy can be realized with the control strategy. But it reduces the quantity of vehicle yaw rate. By compared with 2WS, zero side slip angle from front feedback gets unacceptable performance of handling sensitivity. So a PID compensate control strategy is proposed to improve handling sensitivity.Then, based on the physical parameters of a vehicle, ADAMS platform is used to build a whole vehicle model in order to investigate the characteristics of 4WS. With the help of C#, a template file covering the subsystems of vehicle suspension system is used and applied to adjust the K&C performance of the vehicle. It is the basis for further research on vehicle characteristics. Then, some typical experiment cases for studying vehicle handling and stability are chosen to for the development of the control strategy of 4WS. At the same time, the co-simulation environment of ADAMS and Simulink is built for the further application.Because of the diversity and complexity of vehicle handling, the control strategy based on PID will be not capable in vehicle dynamic characteristics. In this paper, along with the study on the control strategies of zero vehicle side slip angle and yaw rate, a fuzzy control for 4WS is presented to deal with the diversity and complexity of vehicle handling. In the presented fuzzy control strategy, the error of yaw rate, vehicle speed, hand steering wheel angle and the rate of hand steering wheel are the inputs of fuzzy control strategy. According to typical experiment cased for vehicle handling and stability,12 fuzzy rules are used to get the quantity of output.Finally, the feasibility of the purposed fuzzy control strategy for 4WS is verified by typical experiment cases such as hand steering swept, double line change and central steering. The investigation is carried out by the architecture of ADAMS and Simulink co-simulation and the application of the presented fuzzy control strategy for 4WS. It is shown from simulation results that the presented control strategy is viable and vehicle handling and stability can be improved with the use of 4WS. These can also be shown by the two key dynamic parameters vehicle side slip angle and yaw rate when compared with 2WS. The research results can be used for further development of 4WS.