Group Control Strategy Of Spot Welding Based On Multiple Objective Majorization Theory

In spot welding plant, the electric network is struck seriously, which is caused by the disorder working of various spot welding equipments. Exactly because of these factors, welding quality and product rhythm are being effected heavily. Therefore, it is necessary to adopt the guoup control technology to stabilize electric network and production rhythm. The problem to be solved with group control system of spot welding is complicated and nonlinear.Moreover, it is a non-determinacy and multiple objective stochastic decision problem. Therefore, whether the control algorithm designed is reasonable or not will be critical in the whole group control system.In spot welding plant, the control algorithm of group control system used is simple without considering the complex multiple objective requirements. Aimed at the research of control algorithm of spot welding, this project will try to establish the multiple objective majorization model of group control and specific control strategy.The production state of spot welding and the necessity of group control are analyzed in detail. Besides, general methods of group control are introduced in this thesis. In the process of designing the control algorithm, this thesis will originally utilite the multiple objective majorization theory in the group control model. It is a nonlinear theory which is considered to be a optimal method for solving multiple objective requires in control system. This thesis introduces the theory in detail, including the mathematic model and solution procedure and so on.In this thesis, the main majorization objects for control algorithm of group control are minimum average waiting time of welding, maximum number of online spot welding machine, minimum consumption of energy of voltage transformer. The last two objects are inconsistent with each other. But Multiple objective majorization can solve this problem well. Against these majorization objects, the object functions will be established and solution method will be given.The scheduling strategy based on priority level will be intrduced in the group control model. In this thesis, welding signal application will be given. The priority level will be used in the multiply of spot weld completion rate and application times. The spot welder which has high-priority level will be welding at first. At last, intergrality control strategy of the spot welding group control will be confirmed on the base of basic rules and multiple objective majorization model. This intergrality control strategy will realize the multiple objective majorization, which uses scheduling strategy based on the rule of guarantee on product rhythm.