In the Past, the full use of the robot in assembly process has been restricted primary because of the requirement that the parts to be assembled should be machined preliminarily with high accuracy and clearance, and also because of the lack of appropriate techniques which can be widely applied to the industrial processes. In the assembling process, many difficulties stem from the fact that the assembly operation is impossible or the parts to be assembled can be damaged by reaction forces due to even little misalignment in part mating. Lately the assembling technique have been developed in two areas. They are passive accommodation and active accommodation. The former is that the reaction forces are reduced by flexibility of robot hand and the latter is that the misalignment is to be corrected based upon its sensitivity. In this thesis, we layed the purpose on the development and design of the wrist of robot hand which has both flexibility and sensitivity.
The flexible structure of this wrist is linkage system composed of sheet springs and bearings, and the sensible structure is bridge circuit of the strain gages attached to its springs. By measuring strain gage output in assembly using this wrist, the reaction forces between peg and hole, or peg and Gripper can be analysed. These experimental data have been compared to theoretical data by taking account of effects of different parameters(clearance ratio, positioning error, and compliance length). The basic concept of the flexibility was based upon RCC(Remote Center Compliance), and sensitibility of it is similar to Hi-T hand in the point of using strain gage sensors. In this thesis, we analysed the characteristic performance of this wrist for assembly both theoretically and experimentally, furthermore a control algorithm for active accomodation is developed, and evaluated by computer simulations.
