Performance Guaranteed Robust Tracking Control of Electro-Hydraulic Systems With Input Delays and Output Constraints

This article addresses the challenge of achieving prescribed performance robust control for electro-hydraulic systems (EHSs) subject to input delays and output constraints. Firstly, a novel shift function that incorporates the information of input delays is introduced to construct a barrier function (BF). By stabilizing this BF, the output of the EHSs is guaranteed to reach the specified bounds within the prescribed time. Furthermore, by introducing the error transformation functions and the auxiliary function, we handle the tracking error constraints of EHSs in the presence of input delays without imposing any restrictions on the initial relationships between error variables and predefined boundaries. Finally, the proposed controller design does not rely on any specific knowledge of EHSs and avoids the use of approximation or adaptive techniques. Based on Lyapunov stability theory and proof by contradiction, we prove that the closed-loop system is stable. Experimental results demonstrate the effectiveness of the proposed approach.