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The control forms of the vehicle have transformed from hydraulic or mechanical control to electrical control owing to the increasing demand of automotive safety and soaring development of electronic technology. Compared with the traditional mechanical parking brake system, the electrical control of brake named Electrical Parking Brake (EPB) System presents a variety of advantages. What's more, it shares common actuators and realizes the communication between electrical control systems to advance the vehicle industry to intellectualization. With such superiority, the EPB System has aroused much interest. But the difficulty in building the simulation model lies in the description of friction in screw-nut system of which the nonlinear component causes the hysteresis. However, almost all models found in the literature before are the static friction model with the limit of description of dynamic features like pre-sliding frictional features and parameters variation.

In the field of active safety, the active four-wheel-steering (4WS) system seems to be an attractive alternative and an effective tool to improve the vehicles' handling stability in lane-keeping control performance. Under normal using condition, the vehicle's lateral acceleration is comparatively small, and the mathematic relationship between the small side force excitation and the small slip angle of the tire is in the linear region. Furthermore, the effects of roll, heave, and pitch motions are neglected as well as the dynamic characteristics of the tires and suspension system in this work. Therefore, the linear quadratic control (LQC) theory is used to ensure that the output of the 4WS control system can keep track of the desired yaw rate and zero-sideslip-angle response can also be realized at the same time.