The linear-actuated parallel mechanism that changes the motion characteristic according to the actuator configuration is known. The authors previously (2000) reported on the kinematics and the motion characteristic on the basis of the motion transmissibility. In this report, we analyze the changed in motion characteristics using the measures of manipulability. Indices of manipulability are given with components of the value determined by the singular value decomposition. The typical index is a volume of the manipulability ellipsoid. We clarify the features of the motion characteristics according to a change in the actuator configuration using these indices. Finally, we show the recommended application examples that are designed for mechanisms using the obtained result.

Parallel mechanisms driven by fixed linear actuators promise high speed and high output, thanks to lightweight movable parts. Several types of mechanism applying this mechanical principle are already known. Although these have different methods of actuator arrangement, they may be considered the same mechanism since they can be treated using the same kinematics. However, it is not known how the output characteristics differ with differences in actuator arrangement. The article first shows the general kinematics that can be applied regardless of actuator arrangement. Next, changes are shown in the output characteristics occurring with changes in the actuator layout angle in a linear-actuated parallel mechanism with validity arranged actuators. The movable space and motion transmission indexes were used to determine the output characteristics. A total transmission index integrating the transmission index into the movable space is proposed, and the effects of design parameters other than actuator layout angle were investigated while giving weight to the motion transmissibility. The results show that the best actuator layout angle is 45-75 (deg).

A dexterous micro manipulation system is developed for the application in assembling micro machine, manipulating cell, and micro surgery. We have proposed a concept of a two-finger micro hand, and designed and built two types of hand modules based on parallel mechanisms. In this paper, we mainly discuss the structure of a two-finger micro hand. The structure of the two-finger micro hand is strongly related to the effective work space, or the common work space of two fingers as well as its cooperation control algorithms. We design a structure to be suitable for a two-finger micro hand and made a prototype. Development of useful master device to operate the two-finger micro hand is important issue for the dextrous micro manipulation system. We developed a master device which is operated by one hand. The forefinger and thumb is generally used to manipulate objects by one hand. However, motion of each finger cannot be directly used to move the micro manipulator operational signal. We observed difference between the manipulation by two-finger hand like chopsticks and the manipulation by forefinger and thumb in human hand, and discuss operational algorithm for easy manipulation. By using this system for the micro manipulation, we evaluated effectiveness of the two-finger micro hand. In the actual micro manipulation, we succeeded to pick up, place and rotate a micro glass ball having size of 2 microns. The positioning accuracy is less than 0.1 micron.