Model-Based Adaptive Command Filtering Control of an Electrohydraulic Actuator With Input Saturation and Friction

Abstract

This brief improves the motion precision of a pump-controlled electrohydraulic actuator with input saturation and heavy friction. A model-based adaptive commander filtering control (CFC) with the integration of an anti-windup auxiliary system and friction compensation is proposed. Firstly, CFC is designed to solve the problem of the “explosion of complexity” in the classic backstepping design technology, which reduces the online computation burden and is more suitable for industrial applications. Next, an auxiliary dynamic system is introduced to handle the effect of input saturation. The Nussbaum functions are adopted to avoid the derivative singularity of approximate saturation function and improve the anti-windup control performance. Moreover, the designed controller theoretically guarantees asymptotic stability, and the boundedness of all closed-loop system signals is guaranteed. Finally, using a modified continuous LuGre model, a friction compensator is designed in order to improve tracking precision. Comparative experimental results demonstrate the effectiveness of the proposed anti-windup and friction compensation approaches.

Keywords

• Input saturation
• command filtering control (CFC)
• electrohydraulic actuator
• Nussbaum function
• friction compensation