Control Force Compensation and Wear Monitoring of Variable Stiffness Joints in Drive Machining Process

Wu Yan-Chen

doi:10.1155/2021/5524323

Abstract

Aiming at the joint flexibility and wear state existing in the process of driving mechanical parts, this paper first proposes a stiffness and position decoupling control method for variable stiffness joints, which realizes the joint position control and the unity of joint compliance. The joint stiffness model was obtained by using the static relationship between the Jacobian matrix and the model, and the nonlinear equations composed of the mechanical model and the stiffness model of the variable stiffness device were solved by the optimization method to realize the nonlinear decoupling of the stiffness and position of the variable stiffness joint. Secondly, this paper proposes an online monitoring method of wear state in the machining process based on machine tool information. In this method, OPC-UA communication technology was used to collect and store the information of CNC machine tools online, and the internal process information related to the wear of the machine tools was obtained. Based on such information and the corresponding wear information, a wear state recognition model is established by using a convolutional neural network. The feasibility and effectiveness of the proposed compliance control scheme and the performance of online monitoring of wear condition are analysed and verified by simulation experiments.

Highlights

In order to achieve high motion precision, large load capacity, and easy-to-implement tracking control in traditional industrial machining, high-rigidity joint drivers are usually used [1, 2]. e rigid drive can move to a specified position or track a predefined trajectory
Active compliance usually controls the relationship between contact force and contact displacement through force feedback [7, 8] to achieve active safety in machining
Aiming at the problems of joint flexibility and wear state, this paper firstly proposes a stiffness and position decoupling control method suitable for driving variable stiffness joints, which realizes joint position control and at the same time realizes the unity of joint compliance

Summary

Introduction

In order to achieve high motion precision, large load capacity, and easy-to-implement tracking control in traditional industrial machining, high-rigidity joint drivers are usually used [1, 2]. e rigid drive can move to a specified position or track a predefined trajectory. 3. Variable Stiffness Joint Control Force Compensation and Online Monitoring of Wear Status

Results

Conclusion