基于多色集合约束模型的车间层印刷电路板组装优化

针对多组装设备、多组装任务的车间层印刷电路板（PCB）组装优化问题，提出了一种将多色集合与遗传算法（GA）相结合的新的优化方法。基于多色集合理论，用数值围道矩阵描述了复杂PCB组装工艺流程中组装优化问题的设备资源约束和工艺约束，建立了PCB组装的优化约束模型。约束模型使得遗传算法始终在有效解空间中进行搜索，不仅简化了GA适应度值的计算，还可通过约束模型的简单修改，动态描述受设备故障和组装任务变化等因素影响的车间层组装优化问题。实例计算结果表明，该方法能显著提高车间层PCB组装优化问题的求解效率，实现车间层PCB组装的动态优化。

Analysis and Research of Returnability for Rhombic Vehicles

Since the special layout of steering system,the rhombic vehicle cannot
obtain the returnability by means of the steering wheel’s orientation parameters.
A spring returnable structure was used to turn around the revolving drum of the steering system to carry out the returnablity of the steering wheel.
The analysis of steering resistance torque and returnable torque suggests that extra torque is necessary to obtain the returnability.The formula of the locus was obtained based on the analysis.The returnability test suggests the spring returnable system can ensure good returnability of the rhombic vehicles. 