Development of MAGLEV micro hand for assembly and machining

近年来，微电机和微机械部件在微机械和生物领域得到了发展，其中一些已经投放市场，而传感器和处理器已经小型化。因此，制造具有高水平功能的微机械系统在原则上是可能的。然而，传统的微型机械制造是在显微镜下使用微操作器完成的，缺乏自主性。此外，它还缺乏钻孔等简单加工的能力。本研究的目的是开发一种用于灵巧装配和加工的微操作手。对于灵巧的操作，力控制是有效的。本研究对微操作手的机构和控制进行了研究。手形设计包含以下重要特征。首先，采用磁悬浮技术，实现了不使用力传感器的力控制。其次，每个手指被约束到一个平行运动机构。这种机构适合加工，因为连接在手指上的刀具的方向保持不变，并且该机构本身在加工时可以抵抗大的反作用力矩。第三，手由三个自由度的两个手指组成，因此可以应用于包括组装和加工在内的各种任务。在控制方面，设计了主从协调控制系统，主手指采用新设计的PID扰动观测器进行位置控制，从手指采用PD阻抗控制进行力控制；实验微操作手由并联机构、激光直接位置测量传感器和新设计的电磁执行器组成。利用这只手，成功地完成了微拉伸、微钻孔、孔中导线等微加工任务，达到了本研究的目的。

Micro motors and micro mechanical parts have been developed recently in micro-machine and biological areas, and some of them are in market, while sensors and processors are already miniaturized. Therefore, manufacturing of micro machine systems with high level functions is possible in principle. However, conventional production of micro machines is done using micro manipulators under the microscope and lack in autonomy. Moreover it lacks in a capability of simple machining like drilling.The aim of our research is to develop a micro operation hand for dexterous assembly and machining. For dexterous operations, force control is effective. Mechanisms and controls of micro operation hands have been investigated in this research. The hand design contains significant features as follows. First, magnetically suspension technology is adopted to realize force control without using force sensors. Second, each finger is constrained to a parallel motion mechanism. This mechanism is suitable for machining, since the orientation of a cutter attached to the finger is kept constant and the mechanism itself can resist large reaction torques while machining. Third, the hand consists of two fingers with three degrees of freedom and thus it can be applied to various tasks including assembly and machining. Concerning the control, a master-slave coordinate control system has been designed, where the master finger is position controlled with a newly designed PID disturbance observer, while other slave finger is force controlled with a PD impedance control.An experimental micro operation hand was developed which consists of the parallel motion mechanisms, laser displacement sensors for direct position measurement and newly designed electro-magnetic actuators for direct actuation. Using this hand, various micro tasks such as micro drawing, micro drilling and wire in hole were successfully conducted and the goal of this research was achieved.