Designing sliding mode with integral control for angular rotation of a link by linear electrohydraulic actuation

Precise control of link rotation through linear actuation system invokes considerable research interest in the emerging field of electrohydraulic robotics for negotiating heavy external loads. Major challenges emerge for achieving precise control despite wide ranges of demands and disturbances overcoming severe nonlinearities of an electrohydraulic system. A set up has been commissioned to generate angular motion of a link by linear eletrohydraulic actuator. An advanced integral control has been developed in combination with first-order sliding-mode control, or 1-SMC, which is withdrawn for small value of the sliding variable to avoid inherent chattering due to SMC. The controller has been executed in the joint space of linear actuation of a cylinder-piston arrangement through kinematic transformation of the output space of rotation of a link. Most notable outcome of the proposed design is control with low chattering of the control voltage to the valve and its superiority over the conventional PI has been attributed in this study.