THE STUDY OF KINEMATICS AND TRAJECTORY PLANNING OF A 9-DOF SERIAL REDUNDANT ROBOTIC MANIPULATOR

Abstract

A serial manipulator exhibits kinematic redundancy when the number of dimensions in its joint space exceeds that of its end-effector space. This paper proposes a solution to resolve the redundancy issue in a 9-Degree-of-Freedom (DOF) serial manipulator. The solution involves segmenting the robot's kinematic model into two sections: a 3-DOF base (axes 1-3) and a 6-DOF body (axes 4-9). Denavit-Hartenberg (D-H) parameters and homogeneous transformation matrices are used to formulate the forward kinematics equations for both sections. Subsequently, the inverse kinematics solutions for each section are derived using the Jacobian pseudo-inverse method. The proposed method's effectiveness is tested by commanding the base and body sections of the 9-DOF manipulator to follow two independent trajectories simultaneously, demonstrating its ability to generate dexterous motions. An experiment to assess the manipulator's capability to maneuver its end-effector along a specified path while its redundant links follow another, all while avoiding obstacles in a constrained environment is conducted. The results show that the end-effector and redundant links successfully track their respective trajectories with minimal position error and no collisions with the obstacle. In conclusion, the proposed method has been successfully demonstrated to effectively address the kinematic redundancy problem in a 9-DOF serial manipulator.