Development of a micro-manipulation system having a two-fingered micro-hand

A dexterous micro-manipulation system has been developed for applications in assembling micro-machines, manipulating biological cells, and performing micro-surgery. We have proposed a micro-hand having two fingers, a prototype of which has been designed and built using parallel mechanisms. In this paper, we discuss the structure of our micro-hand and its operation system. The structure of the two-fingered micro-hand is strongly related to its effective workspace, i.e., the common workspace of its two fingers, as well as its cooperation control algorithms. The design of the micro-hand has been influenced by consideration of the usage of chopsticks. A calibration method based on least-square error is proposed for three degrees of freedom (DOF) translational motion in task coordinates fixed under a microscope. Development of a useful operational device to control the micro-hand is important for achieving dexterous micro-manipulation. A force feedback system would be ideal for such manipulation. In the case of micro-manipulation, though, a sensor with high resolution and multiple sensing axes is needed. There is no sensor meeting this demand currently. In order to achieve micro-manipulation without the force feedback system, an operational system which can be controlled with natural operational feeling like manipulation of actual human hand, is important. We have developed an operational device which is controlled by one hand. The forefinger and thumb are used to manipulate microscopic objects in tele-operation. However, due to kinematic dissimilarity between the master and the micro-hand, the motion of the fingers cannot be directly used as operational signals to move the micro-hand. We have therefore developed an operational strategy which compensates for this dissimilarity, thus providing for easy manipulation. The effectiveness of the two-fingered micro-hand and micro-manipulation system has been demonstrated by picking up and positioning a microscopic glass ball, 2 μm in diameter. The positioning accuracy is less than 0.1 μm. Other objects, such as a latex ball, micro stick, and biological cell, can be manipulated as well.