Self-tuning quantitative feedback theory for parallel force/position control of electro-hydrostatic actuators

Abstract

Hydraulic power systems and actuators play an important role in modern industry because they have many advantages over other technologies with electric motors, high durability, and the ability to produce large force at high speeds. In order to improve the control performance of electro-hydrostatic actuators, the aim of this paper is to propose a novel parallel control strategy based on the self-tuning quantitative feedback theory (STQFT) technique and then applying it to control force and position of a new kind of hydraulic experimental system - the electro-hydrostatic load simulator (EHLS). The EHLS is very useful to test the force or/and position control of electro-hydrostatic actuators (EHAs). The STQFT controller is designed to satisfy the robust criterions based on the QFT technique. Then the parameters of the STQFT force and position controller are automatically tuned online to minimize the system error by using the gradient descent method and speed up convergence. Consequently, the EHLS using the novel controller is able to obtain the force and position control performance with high precision in a wide range of working conditions including perturbations. Experiments are carried out to evaluate the effectiveness of the proposed parallel force and position control method applied to the EHLS system.