Abstract: Base on a structural synthesis method of the theory of reciprocal screw, the design method of parallel manipulator of 3 rotational DOFs for pose adjusting of radar and other equipment was proposed. Furthermore, the linear relationship of 3 limbs when platform singularities happened was analyzed. With the specific constraints provided by 3 limbs, a construction synthesis method that can completely avoid platform singularities is introduced. Finally, 3 novel manipulators are sketched as design examples.

Key words: automatic control technique , parallel manipulator , theory of reciprocal screw , platform singularity , rotational motion