Development of a General 2-DOF Space Module

This paper presents the concept of a general two degrees-of-freedom space module or TODOM. General TODOM is made up of three basic modules: one link module and two revolving modules. The reliability of the TODOM is improved by mutual backup of the control systems of the two revolving modules. Every revolving module corresponds to one degree-of-freedom (DOF). The two axes of the revolving modules can be configured to different orientations or positions by specific design of the mechanical interfaces between the three basic modules. Several such differently configured TODOMs can be assembled into some needed kinds of space manipulators that have even numbered DOF. By using integration design method, the mass and volume of the TODOM is dramatically reduced, and the system reliability of the manipulator can be improved. The rationality and feasibility of the TODOM concept is testified by the development of a 2-DOF wrist whose two joint axes are orthogonal