Position Control with ADRC for a Hydrostatic Double-Cylinder Actuator

Bin Wang,Rui Chang,Hengyu Ji

doi:10.3390/act9040112

Abstract

A compact and flexible hydraulic double-cylinder actuation scheme is proposed for use in applications, especially where power density is extremely demanding. In view of flexible amounting requirements, long and thin hoses were utilized to connect two cylinders. Affecting the actuation preciseness, volume variation of the hoses caused by pressurized oil and bubbles was the main problem the system encountered. In this study, an active disturbance rejection control (ADRC) strategy was adopted for the improvement of displacement control performance under uncertain external load. After the experimental verification of the necessity of a hose model for the system, a centralized-parameter hose model was constructed where the coefficients are determined on the basis of the experimental data. Additionally, the system and the controller proposed were mathematically modeled. Simulation results shows that the system using ADRC exhibited higher displacement accuracy and better dynamic performance than that using PID (Proportion-Integral-Derivative) or fuzzy PID. ADRC has a stronger disturbance rejection ability. ADRC is an effective solution to nonlinear control of systems with uncertain parameters or various loads.

Highlights

Due to small size, light weight, fast response and high accuracy, the electrohydraulic servo system has been widely used in many fields such as aerospace, robot, construction industry, etc. [1,2].At present, hydraulic actuation mainly includes valve-controlled and pump-controlled schemes.The valve-controlled system has been widely used in engineering fields owing to its high response frequency and power-to-weight ratio [3]
A robust fixed-gain linear output pressure controller was designed for a double-rod electrohydrostatic actuator using quantitative feedback theory (QFT) to provide desired transient responses, tracking bandwidth, robust stability, and disturbance rejection for the closed-loop system [15]
This paper focuses on the active disturbance rejection control strategy for a hydrostatic double-cylinder actuator, which was systematically analyzed and compared with the conventional

Summary

Introduction

Light weight, fast response and high accuracy, the electrohydraulic servo system has been widely used in many fields such as aerospace, robot, construction industry, etc. [1,2]. A speed and position control system using double cylinders adopted a hydraulic accumulator instead of conventional oil tank, and an electric motor was used to achieve closed-loop control [7]. It is extremely necessary to model the hose in small-size and high-pressure displacement control systems. A robust fixed-gain linear output pressure controller was designed for a double-rod electrohydrostatic actuator using quantitative feedback theory (QFT) to provide desired transient responses, tracking bandwidth, robust stability, and disturbance rejection for the closed-loop system [15]. NLSEF uses the total perturbation observed by the ESO to generate the control variables, so as to ensure the stability of the system This can provide a theoretical basis for ADRC application in double-cylinder hydraulic actuators.

System Principle

System Mathematical Model

Controller Design

Results

Conclusions