Online Estimation and Control for Feed Drive Systems With Unmeasurable Parameter Variations

Tiancheng Zhong,Wencheng Tang,Ryozo Nagamune,Alexander Yuen

doi:10.1109/access.2020.2974240

Abstract

This paper develops an online parameter estimation and control method for both rigid and flexible feed drive systems with unmeasurable parameter variations. The perturbations of the state-space model caused by the parameter variations are formulated, thereby making it possible to obtain the parameter variations in real-time by estimating the perturbations. To estimate the perturbations, they are regarded as the extended states and estimated through the extended-state-observer. With the estimation method, a novel state feedback control structure with double integrators is further proposed, which can eliminate the steady-state tracking error at constant velocities. The H$_\infty $ optimization technique is used to design the proposed state feedback controller. A simulation is conducted that integrates the estimator and the controller for a ball screw setup with mass-dependent resonant modes, where several proposed state feedback controllers are linearly interpolated into a gain-scheduling controller and scheduled by the estimated mass. The results demonstrate that the designed gain-scheduling state feedback controller outperforms a linear-time-invariant state feedback controller and an adaptive backstepping sliding mode controller. The proposed method is experimentally validated on a rigid linear-motor-driven motion stage, of which the results indicate the proposed estimation method can accurately estimate the parameter variations.

Highlights

The rapidly developing high-speed machining requires fast and accurate feed drive systems
In this paper, a significant problem caused by the parameter variations in feed drive systems was overcome by proposing a novel method of online estimation and control
The core concept of the proposed parameter estimation method is regarding the perturbations caused by the parameter variations as the extended states, formulating a new system containing the extended states, and estimating the extended states through the observer

Summary

INTRODUCTION

The rapidly developing high-speed machining requires fast and accurate feed drive systems. Various advanced control methods have been applied to feed drive systems, e.g., sliding mode control [2], state feedback control, including pole placement [3] and linear quadratic regulator [4], additional feedback loop control [5], H∞ robust control [6], and active disturbance rejection control [7]. T. Zhong et al.: Online Estimation and Control for Feed Drive Systems With Unmeasurable Parameter Variations methods can consider variations in the unmeasurable parameters by regarding them as uncertainties and design either robust linear-time-invariant (LTI) controller [13] or advanced gain-scheduling controller [14], these methods can not avoid the inherent conservatism that will limit the performances of control systems. The extensive simulation and experiment indicate the proposed parameter estimation method can accurately obtain the parameter variations, and the impacts of the unmeasurable parameter variations can be well compensated by using the estimated parameter to schedule the controller gain

PRELIMINARIES

PERTURBATION ESTIMATION THROUGH EXTENDED-STATE-OBSERVER

STATE FEEDBACK CONTROLLER DESIGN

SIMULATION

Findings

CONCLUSION