Development of an Assembly System by Using of the Effects of Ultrasonic Vibration

针对装配过程中间隙小于几微米的零部件在装配过程中由于卡死或楔入等现象而难以实现完全自动化的问题，提出了一种新的间隙小零件装配系统的实现方法。非常精心设计的机制，如RCC机制和高层次的控制方法，作为状态反馈控制与随机模型已被用于这些过程中与灵活的机器人。然而，即使使用上述复杂的系统，非常接近的交配偶尔也会失败。这就是为什么在传统的处理中，桩与孔之间的相互作用力被认为是实现控制的被动信息，在本研究中，试图通过在零件表面施加超声波振动来主动地利用相互作用力。在插入过程中，钉的纵向振动或弯曲振动减小了钉与孔之间的接触点处的表观摩擦，并且产生了表面力，该表面力将钉驱动到孔部分中，如在线性超声波马达中那样。通过将超声波振动应用于要配合的钉或孔中的一个，插入运动变得平滑和容易。在将超声振动应用于嵌件加工的具体方法上，提出了周期冲击法和点支承法。研制了一个SCARA型机器人自动装配原型系统，系统中采用了纵向振动和弯曲振动相结合的方法。在几百微米左右的粗控制下，实现了小于几微米间隙的平滑配合。

This study aims to realize an assembly system with a new method for inserting operations of the parts with very close clearance.In assembly process, it is difficult to realize full automation of parts insertion with close clearance less tan several micrometers because of jamming or wedging phenomena in the mating process. Very carefully designed mechanisms such as RCC mechanisms and high level control methods as state feedback control with stochastic models have been used in these processes with flexible robots. However, very close mating occasionally ends in failure even in use of above sophisticated systems. This is why the reciprocal force actions between peg and hole are considered as passive informations for the attainment of control in the traditional treatment.In this study, it is attempt to use the reciprocal force actively by means of the application of ultrasonic vibration onto the surface of the parts. Longitudinal vibration or bending vibration of a peg in inserting process decreases apparent friction at the contact point between the peg and a hole and generates surface force which drives the peg into the hole part as in a linear ultrasonic motor. Inserting motion becomes smooth and easy by the application of ultrasonic vibration to one of the peg or the hole to be mated. As for some concrete methods of the application of ultrasonic vibration onto the inserting process, periodical impact method and point supporting method for vibrating elastic bodies are invented. A prototype automatic assembly system with a scara type robot was developed in which the combination of longitudinal and bending vibration were applied. Smooth mating with the clearance of less than several micrometers was realized under rough control of about several hundred micrometers.