| AWID/AWIS is a kind of advanced vehicle of which all-wheels can be driven and steered independently. Compared with traditional vehicle, AWID/AWIS vehicle has more and flexible steering and driven style. For example, each wheel can be driven with optimization slip rate and provide optimization force, which can improve the maneuverability, dynamic performance and safety of vehicle by controlling the steering and driving coordinated. It is the development tendency of advanced vehicle, military vehicle, unmanned vehicle and wheel mobile robots with high speed in the future.Supported by the 863 projects, the 4WID/4WIS vehicle, which is the most typical vehicle of AWID/AWID, is studied in this paper. The research contents of this paper include:Anti-skid system, vehicle dynamic stability control system of 4WID/4WIS, and the method for estimation of utilization adhesion coefficient and road identification, which is strongly associated with Anti-skid and VDC.The main work of this paper is as follows:1. Firstly, three models were built, which were a quarter dynamic model of vehicle, linear dynamic model with two freedoms for steering, and nonlinear dynamic model with nine freedoms for the whole vehicle. They were used for Anti-skid system design, the reference model of yaw stability controller and control algorithm verification.2. By considering the force between the tire and road as an extended state of the system, a nonlinear second-order Extend State Observer was proposed. The longitudinal force was observed by ESO, so the utilization adhesion coefficient was estimated and the road was identified by curve of tire real time. This method avoided the noise caused by direct calculation, and cut back the cost of the sensor for measuring the road. Simulation of driving and braking indicated that this method is robust and accurate under typical road conditions and abrupt road changes.3. According to the uncertainty and nonlinearity of Anti-skid system (include Anti-lock Braking and Anti-Slip Reguration), Active Disturbance Rejection Control was introduced to design ABS and ASR system, whose target were to trace the anticipant slip ratio. Genetic algorithm was adapted for adjusting the parameters of ADRC controller. Simulation of some conditions indicated that ABS and ASR based on ADRC are robust to parameters perturbation and external disturbances. The ABS system which can be adaptive to road was designed based on foregoing works. It regulates anticipant slip rate during the braking process according to the result of road identification. And it takes full advantage of the forces between road and tire during braking process.4. During the process of steering with high speed, the side slip angle of tire is larger and in nonlinear cornering properties regional, the controller designed on linear model with two freedoms would has some limitation. To solve this problem, nonlinear cornering properties of tire model and nonlinear 4WID/4WIS vehicle model with two freedoms of vehicle were built based on parameters of 4WID/4WIS, the validation of these models were testified in succession. An Integrated yaw stability controller composed of Active Front Wheel Steering, Active Rear Wheel Steering and Direct Yaw moment Control were designed, Fuzzy Linear quadratic regulator was adopted in this controller. Simulation results indicated the validity of the nonlinear model and the robustness of control method.5. Sometimes parameters of 4WID/4WIS can not obtained. After analyzing the coupling relationship between vehicle side slip angle and yaw rate, a fuzzy yaw stability controller composed of AFS, ARS and DYC was designed based on the strategy 'when|β| is small, the main aim is to follow the anticipant yaw rate, and when|β| is big, the main aim is to reduce vehicle side slip angle'. Contrasting simulation results based on nine freedoms model indicated the validity and feasibility of this method.6. The configuration of the control system was introduced briefly. The validity of yaw stability control system and ABS control method proposed in this paper were proved by experiment.Achievements of this paper possess preferable applicability, and they can be popularized and applied on other AWID/AWIS vehicle with different number of wheels.
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