【作者】 孙向飞；

【导师】 李冬青；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2007， 硕士

【摘要】 在汽车点焊车间中,由于各种点焊设备的无序工作,对电网造成了极大的冲击,严重影响了焊接质量和生产节拍。因此有必要对焊机进行群控,以起到稳定电网,保证生产节拍的目的。焊机群控系统所要解决的是一个复杂的、具有非线性和不确定性的多目标随机决策问题。因此,设计合理的群控算法就成为控制系统要解决的关键问题。在点焊车间中,现有的群控系统算法较为简单,没有考虑群控复杂的多目标要求。课题以点焊群控算法的研究为目的,尝试建立点焊群控的多目标优化模型,并最终给出具体的控制策略。本文对点焊车间的生产现状以及点焊机进行群控的必要性进行了详细分析,并介绍了群控的一般实现方法。在设计群控算法时,本文创新性地将多目标优化理论运用到群控模型中。多目标优化理论是一种非线性优化理论,是最佳的解决群控多目标要求的算法之一。本文详细的介绍了这种理论,包括数学模型的建立,求解等等。本文中点焊群控多目标优化模型的优化目标主要有焊接平均等待时间最小、在线焊机数量最多、变压器能耗最小。在线焊机数量最多和变压器能耗最小是相互矛盾的两个优化目标,这也是多目标优化理论所要解决的问题。本文分别针对这几个优化目标建立了目标函数,并给出了求解的办法。本文将基于优先级的调度策略引入到群控模型中,给出了焊接申请信号优先级的确定方法,即以焊点完成率和申请次数的乘积做为优先级等级。优先级高的焊机先焊接。最后,本文结合群控的基本规则和多目标优化模型确定了点焊群控的总体控制策略,即在保证生产节拍的前提下运用优先级调度策略实现多目标优化。更多还原

【Abstract】 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.更多还原