NOVEL 4-DOF SCARA PARALLEL ROBOT WITH CYLINDRICAL WORKSPACE

In this paper, we present a novel 4-DOF SCARA parallel robot. The 2-DOF portion of the novel robot has been proposed before and consists of an end-effector connected to the base through two legs of type RRR and one passive constraining leg of type RP, where all the base-mounted revolute joints are coaxial. Contrary to SCARA robots based on the four-bar mechanism (RRRRR), the novel robot has a fully cylindrical workspace with no voids or parallel singularities in it. The novel robot has essentially the same workspace as that of a similarly sized ceiling-mounted SCARA serial robot (RR) with links of equal length. However, the proposed robot has the advantage of having all motors mounted on the base. We present the 2-DOF portion of the robot, its kinematic analysis, and its optimal design, and finally propose a mechanism design for the 4-DOF SCARA parallel robot.