Kinematic Analysis, Control and Motion Planning of a Redundant (6+3)-DOF Hybrid Parallel Robot

This paper introduces a (6+3)-DOF spatial hybrid parallel robot. It presents an innovative 3-DOF parallel wrist-gripper assembly, building upon the advancements highlighted in previous work, aiming to significantly enhance the base robot's capabilities. This assembly comprises a zero-torsion 2-DOF parallel wrist and a 1-DOF parallel gripper. The wrist enables a large singularity-free range of motion by generating a 2-DOF sphere-on-sphere pure rolling motion. This extensive singularity-free 2-DOF motion of the wrist facilitates seamless and precise manipulation of objects across various orientations, rendering it suitable for diverse applications such as assembly, pick-and-place, and inspection tasks. The paper leverages a geometric approach to derive analytical solutions for the robot's inverse kinematic problem. Validation of the derived inverse kinematics equations is carried out using MSC Adams. Additionally, a straightforward PD position control scheme is proposed for the control of the robot. Subsequently, a physical prototype is constructed, and experimental validation is conducted to demonstrate the effectiveness of the proposed controller. Overall, the (6+3)-DOF hybrid parallel robot proposed herein exhibits substantial potential for en-hancing the efficiency and adaptability of robotic manipulators across a broad spectrum of industrial and research-based applications.