Model-Free Adaptive Control of Direct Drive Servo Valve of Electromagnetic Linear Actuator

Jianhui Zhu,Jianguo Dai,Cheng Wang

doi:10.1155/2018/7105872

Abstract

An electromagnetic linear actuator (EMLA) has a promising application in direct motion control. However, ELMA will inevitably inherit uncertainties in the face of load changes, system parameter perturbation, and inherent system nonlinearities, all of which constitute disturbances adversely affecting the precision and adaptability of the control system. A model-free adaptive control (MFAC) strategy based on full form dynamic linearization (FFDL) was proposed to reduce the sensitivity of the control system to the disturbances. An adaptive control of direct drive servo valve was achieved based on the online interaction of characteristic parameters and control algorithms. The feasibility and precision of the proposed algorithm were verified through simulation and experimental results. The results show that the proposed algorithm could achieve adaptive adjustment of the servo valve response at different openings of 0-3 mm without changing control parameters, with the response time controlled within 10ms and steady state error less than 0.04mm. Furthermore, the proposed algorithm had better robustness and capacity of resisting disturbance.

Highlights

Electromagnetic linear actuator (EMLA) has a wide range of applications in the field of linear motion control, because of high-precision, high-response, and nonintermediate conversion [1, 2]
Gas Outport (a) Schematic diagram (b) Three-dimensional model diagram. It mainly consists of magneto-resistive displacement sensor, electromagnetic linear actuator, poppet valve, seat, and valve cover fixed to the central axis
It can be seen that the controller mainly consists of model-free adaptive controller module for generating control quantity u(k), estimator module for estimating the algorithm in pseudo-gradient vector, the controlled object- direct drive servo valve of EMLA, and submodule constituted by the nonlinear model

Summary

Introduction

Electromagnetic linear actuator (EMLA) has a wide range of applications in the field of linear motion control, because of high-precision, high-response, and nonintermediate conversion [1, 2]. EMLA has been widely applied in electromagnetic engine valve, automatic transmission, and freedom motion platform of six degrees. It has drawn more and more attention as a part of electrical-mechanical conversion device of direct drive servo valve [3,4,5]. For direct drive servo valve, the control algorithm is normally based on accurate modeling for control object, which is very difficult to be achieved; control effect is poor [10, 11]. For discrete-time nonlinear systems, MFAC (Model-Free Adaptive Control) uses a new dynamic linearization method and a concept of pseudo-partial derivative. A model-free adaptive control strategy was proposed based on full format dynamic linearization to achieve better control effect and high-response. Simulation and test were carried out to verify the adaptive control of ELMA for direct drive servo valve

System Description

Model-Free Adaptive Controller Design

Results and Analysis

Conclusion