PID control for a height adjustable wheel-direct-drive system via time-varying samplings

This paper is concerned with the sampled-data PID control for a new wheel-direct-drive system of a quarter-car model, which is designed with both vehicle body height adjusting function and wheel driving function. Based on the analysis of working mechanism and mechanical dynamics, the state-space models of the vehicle body height adjusting and wheel speed tracking systems are built, respectively. A sampled-data PID controller via time-varying samplings is constructed and the implementation of the functions of the wheel-direct-drive system is converted into the stability of the closed-loop systems. Stability conditions for the systems via time-varying samplings are derived in terms of linear matrix inequalities and PID control parameters can be obtained by a iteration algorithm based on the cone complementarity linearisation method. A test-bed of a wheel-direct-drive system equipped with a control system that consists of S7300 PLC, some sensors, and a DC motor is established to validate the effectiveness of the proposed modeling and design methods.