A Novel 4-DOF 3UPU-2UPU-RRR Parallel Manipulator with Full Rotational Capability Based on Redundancy

This paper presents a new parallel manipulator (PM) called 3UPU-2UPU-RRR. Such PM is composed of two sub-PMs, i.e., 3UPU and the 2UPU, connected by an RRR chain where the end-effector is set. This kinematic arrangement needs five actuators to provide the 4-DOF, making the proposed PM redundantly actuated. The use of an additional actuator provides the PM the ability to rotate the end-effector unlimitedly. The forward and the inverse position analyses are solved in closed form. Also, its instantaneous kinematics is addressed to identify all its singularities. Eventually, an simulation study demonstrates the unlimited rotation of the end-effector.