Finite-time convergent sliding mode control method for parallel robot combined with robust exact differentiator

Abstract

The invention discloses a sliding mode control method for limited time convergence of a parallel robot for transportation combined with a robust precise differentiator. Carry out kinematics analysis for the parallel robot for transportation and give the expected trajectory; use time-delay estimation technology to obtain the dynamic model including unknown dynamics, external disturbance and friction and other uncertain factors of the parallel robot for transportation in real time; for time-delay To estimate the delay estimation error generated by the technology, a finite-time convergent robust accurate differentiator for the parallel robot system for transportation is designed to observe; further, based on the feed-forward compensation effect of the delay estimation error observation value, a finite-time convergence is designed Sliding mode controller. Through software programming, the finite-time convergent sliding mode control of the parallel robot for transportation combined with the robust and accurate differentiator feed-forward compensation technology is realized. The present invention has significant suppression effect on sliding mode control chattering, and the sliding mode variables and their derivatives converge to the origin in a limited time, thereby improving motion tracking precision.

Description

technical field [0001] The invention relates to a parallel robot for transportation, in particular to a model-free combined robust precise differentiator finite-time convergent sliding mode control method for a parallel robot for transportation. Background technique [0002] In order to meet the engineering application requirements of automotive coating conveying equipment, a parallel robot for conveying was developed based on a parallel mechanism to overcome the lack of carrying capacity and low flexibility of the existing automotive electrophoretic coating conveying equipment that adopts a cantilever beam series structure defect. The parallel robot for transportation has many advantages such as strong carrying capacity, wide applicability of vehicle models, high positioning accuracy, small motion inertia of the end member, no cumulative error, and fast response speed. However, the characteristics of the multi-branch closed-chain structure and the coupling relationship bet...

AI Technical Summary

Problems solved by technology

There are two disadvantages in this method: (1) the control method needs to establish the dynamic model of the parallel robot first, which requires a large amount of calculation; (2) the control law of the approaching law sliding mode control has a discontinuous sign function, which leads to the failure of the sliding mode control. Chattering

This method has the following disadvantages: (1) The control method directly uses sliding mode control to overcome the influence of uncertain factors such as time delay estimation errors, resulting in a large amount of control required, and a large switching gain is easy to aggravate the chattering of sliding mode control; ( 2) This control method introduces an adaptive rule to adjust the control switching gain, but since the obtained sliding mode control law is still discontinuous, the ability to suppress chattering in sliding mode control is limited, and the adaptive parameters are not easy to adjust in practical applications

(3) This control method belongs to the first-order sliding mode control, which can only guarantee the convergence of the sliding mode variables

Images