Forward Kinematics and Workspace Analysis for a 7-DOF Cable-Driven Humanoid Arm

Cable-driven mechanisms have high load capacity. Motivating from the latest research results of humanoid-arm bionics and parallel manipulators, a novel design of cable-driven humanoid-arm, which combines the merits of cable-driven and parallel mechanism, is proposed. This paper introduces the specific structure of cable-driven humanoid-arm. The modes of cables distribution and the coupling among joints are also studied. With analysis of the four-cable approach to drive 3-DOF parallel mechanism, the relationships between cable lengths and joint angles is analyzed, the motion ranges of joint angles are also discussed. Based on the analysis above, forward kinematics and workspace of the manipulator are analyzed, the pose of end-effector relating to base frame is deduced. At last, according to three groups of kinematic solutions, a simulation by ADAMS is carried out to verify the effectiveness of proposed algorithms.