Robust control design for a wheel loader using mixed sensitivity h-infinity and feedback linearization based methods

The existing industry practices for the design of control systems in construction machines primarily rely on classical designs coupled with ad-hoc synthesis procedures. Such practices lack a systematic procedure to account for invariably present plant uncertainties in the design process as well as coupled dynamics of the multi-input multi-output (MIMO) configuration. In this paper, an H_∞ based robust control design combined with feedback linearization is presented for an automatic bucket leveling mechanism of a wheel loader. With the feedback linearization control law applied, stability robustness is improved. A MIMO nonlinear model for an electro-hydraulically actuated wheel loader is considered. The robustness of the controller designs are validated by using analysis and by simulation using a complete nonlinear model of the wheel loader system.