Research on finite frequency robust H∞ control of all-terrain vehicle magnetorheological suspension system

Abstract

To improve the vibration attenuation performance of the all-terrain vehicles (ATVs) equipped with magnetorheological (MR) suspension with parameter uncertainty and time delay in the sensitive frequency band of human body, this study proposed a finite-frequency robust (FFR) ${\text{H}}_{\infty }$ control strategy. Firstly, a MR suspension model with seven degrees of freedom is established. The boundaries of parameter uncertainty and time delay are obtained through the experiment analysis of the MR damper, occupants and cargo mass. Secondly, in the framework of Lyapunov-Krasovskii stability theory, an FFR ${\text{H}}_{\infty }$ controller is designed in the frequency domain of human sensitivity specified in ISO2631 to enhance ride comfort level. Meanwhile, three suspension constrained requirements of suspension deflection, wheel dynamic load, actuator force are also guaranteed. Subsequently, the controller parameters with frequency-dependent characteristics are obtained using the linear matrix inequality (LMI) toolbox. Finally, off-road road experiments are conducted to validate the effectiveness of the designed controller. The results indicate that the FFR ${\text{H}}_{\infty }$ controller demonstrates an outperform capability for attenuate the vertical (4–12.5 Hz), pitch, and roll (0.5–2 Hz) accelerations in the human-sensitive frequency bands compared with the passive and traditional robust (TR) ${\text{H}}_{\infty }$ control algorithms.