Conceptual design and kinematic analyses of a 3-DOF robot wrist

A novel and plug-and-play robot wrist with three rotational degrees of freedom (DOF) is proposed in this paper. The wrist is composed of three independent kinematic chains, each of which rotates with respect to the fixed reference frame. Thus, the output of the wrist is the resultant of the differential motions of the three kinematic chains. The structure of the mechanism is simple and compact with a relatively large orientation capability. Various end-effectors, CCD camera for instance, can be mounted on the wrist through standard interface. The working principle and mechanical structure are described and the mathematical models for inverse and forward analyses are developed. The singularity of the wrist is also obtained.