Development of Prototype Four Piece Servo Manipulator

Traditionally, Mechanical Master Slave Manipulators have been used as dexterous remote handling tools in hotcells. They are usually installed through the wall-sleeves of the hotcells. Second generation of manipulators is electrically powered servo manipulators, which are installed fully inside hotcells on movable support structures. In spite of their superior features, servo manipulators cannot be installed in most of the existing hotcells, due to the lack of the support structure in those cells. In view of this issue, a servo manipulator, called Four-Piece Servo Manipulator (FPSM), suitable for installation in conventional hotcells, through their wall-sleeves, has been developed. The 20 kg capacity FPSM has four distinct parts: the slave arm, the through-tube, the motor unit and the master arm. It combines the technologies of existing Sealed Type Three-Piece Manipulator (TPM) and Servo Manipulators. The FPSM offers maintainability of TPM and ease of operation of Servo Manipulators. The FPSM has been so designed that the Motor Unit can be directly connected to the slave arm (without the through-tube) and can then be mounted on a transporter to be used as conventional servo manipulators. The FPSM is a bilateral mechanism with both master-slave following and force reflection along with other auxiliary features like variable speed indexed motion of major joints, variable force reflection ratio etc. This system is based on a tightly coupled distributed digital micro-processing technique. This paper discusses the mechanical and control design and implementation of FPSM.