Harmonic and synchronous compound control of a dual-valve controlled single-rod electro-hydraulic actuator

Abstract

This article presents a novel harmonic and synchronous compound control scheme based on the dual-valve parallel structure for controlling a single-rod electro-hydraulic actuator with high-precision control and large-flow requirements. Harmonic and synchronous compound control consists of an adaptive robust control layer and a control law allocation layer. In adaptive robust control layer, an adaptive robust control algorithm is designed to deal with the system nonlinearities and uncertainties via backstepping method. Meanwhile, dynamic surface control technique and “lumped flow” are introduced to solve the differential explosion problem and the multiple input-single output control problem. In control law allocation layer, the harmonic and synchronous compound strategy allocates the control law to two valves reasonably based on system flow and valve frequency characteristics. Furthermore, since the effect of the proportional valve dead-zone can be compensated effectively by combining the estimation of the dead-zone flow by adaptive term, the estimation error compensation by robust term, and the allocation method of control law allocation layer, improved tracking performance can be achieved. Finally, both simulations and experiments are demonstrated to illustrate the advantages of the proposed control scheme.