Robust H ∞ control for magnetorheological suspension system of all-terrain vehicles with parameter uncertainties and time delay

The random road disturbance, parameter uncertainty (load mass and viscous damping coefficient of Magnetorheological damper (MRD)), and time delay of actuator may lead to the poor vibration suppression performance for All-Terrain Vehicle (ATV) Magnetorheological (MR) intelligent suspension system. In order to solve the above problems, firstly, a multi-degree-of-freedom dynamic model of the ATV MR suspension system is established in consideration of parameter uncertainties and time delays. Then the boundary of the uncertainty damping coefficient and the time delay of MRD are identified experimentally to the operating condition of ATV. Based on the Lyapunov-Krasovskii stability theory, a H∞ robust controller with parameter uncertainty and time delay (HICUT) is developed, and the controller parameters are solved using linear matrix inequality (LMI). Finally, the effectiveness of the designed controller is validated through simulation and vehicle road tests, respectively. The results demonstrate that both the acceleration of the driver's seat cushion, and pitch and roll angular acceleration of the body are reduced greatly in comparison with the passive control and the HICU without time delay, and the corresponding comfortability and handling stability of the vehicle are improved significantly.