SYNTHESIS AND STUDY OF THE WELDING ROBOT LINK CONTROL ALGORITHM WITH A TECHNICAL VISION ORGAN

Abstract

Traditional construction of control systems for welding robots (WR) is carried out on the basis of local servo drives of links, closed according to the signals of position sensors (encoders) on the shafts of motors. Along with this, to determine the butt position of the welded parts, technical vision organs are often used, according to the signals of which the programmed movement of the links is adjusted. The need for adjustment arises due to differences between the actual and the specified position of the joint due to inaccuracies in the manufacture and fastening of parts, as well as their thermal deformation during welding. Under these conditions, the problem of closing the control circuit of the position of the WR link on the signal of the organ of technical vision, in particular the laser sensor, becomes relevant. This will allow the use of simpler and cheaper speed-controlled drives than position-controlled drives in the WR. The purpose of the work is the construction and research of the system of automatic control of the position of the welding robot link with the closing of the main feedback according to the signal of the technical vision organ. The mathematical description of the control object consists of a model of the speed-regulated sensorless electric drive of the robot link and a model of the laser sensor of the welding torch position. In the synthesis of feedback by modal control, the poles of the controller and the state observer were optimized to meet the conflicting requirements for the system's ability to filter impulse noise at the output of the laser sensor and to provide a fairly rapid response to perturbations. The characteristic polynomials of the controller and the observer are selected according to the standard Butterworth form. The applied polynomial-modal approach to the synthesis of a digital control system for the position of the robot link allowed to perform the task signal with high speed and accuracy in the absence of overshoot. With the help of extended numerical studies, the compliance of static and dynamic quality indicators of the synthesized system of automatic control of the position of the WR link with the initial requirements is confirmed.