This article proposes a novel robust adaptive wheel slip rate tracking control method with state observer. First, a modified tracking differentiator is proposed based on a combination of tangent sigmoid function with terminal attraction factor and linear function to improve convergence speed and avoid chattering phenomenon, and then, the modified tracking differentiator is used as state observer to smooth and estimate the states of the system. Second, a robust adaptive wheel slip rate tracking control law with fuzzy uncertainty observer and modified adaptive laws is derived based on Lyapunov-based method. The fuzzy uncertainty observer is used for estimating and compensating the additive uncertainty, and the modified adaptive laws are used for estimating the unknown optimal weight vector of the fuzzy uncertainty observer and the multiplicative uncertainty. Finally, the performance of the robust adaptive wheel slip rate tracking control method is verified based on the model-in-the-loop simulation system.

This paper proposes autonomous parallel parking for a front-wheel steering vehicle, with highlights on a trajectory planning method and on a trajectory tracking control method. The trajectory planning problem is decoupled into the path planning problem and the longitudinal velocity planning problem to reduce the difficulty of the trajectory planning problem. First, a collision-free path by combining circle arcs with straight line is created to park the vehicle in one or more maneuvers on the premise of meeting the kinematic constraint of vehicle, and then the path is transformed into a continuous-curvature path using B-spline curve. Second, the longitudinal velocity is created using B-spline curve on the premise of meeting the performance constraints of driving and braking system. To execute the generated trajectory, a non-time reference path tracking sliding mode control strategy is deduced by Lyapunov stability theory, and a longitudinal velocity tracking proportional–integral control strategy is proposed based on smooth handoff method. Finally, the parking performance is verified based on model-in-the-loop simulation system.

A nine freedoms nonlinear three-axle vehicle dynamic model was constructed by Matlab/Simulink to analyze the control effect of directional stability for different Anti-lock Brake control algorithm. Algorithms analyzed here contain PID, logic threshold and sliding mode variable structure control algorithm. Then comparing and analyzing the control effect from the aspects of tire/whole vehicle parameters and the phase-plane of slid slip rate and its rate.