Abstract: Aiming at the problems of low stiffness and low precision of traditional cable-driven manipulators, a novel cable-driven 7-DOF anthropomorphic manipulator system is designed with the characteristics of light weight, low inertia, high stiffness and high positioning accuracy at the same time. Using the design principle of modular robotic arm, the entire robotic arm is divided into three parts:shoulder, elbow and wrist. The one degree of freedom (DOF) elbow joint and three DOF wrist and shoulder joints based on closed-loop rope actuation are designed respectively. The encoder is integrated into the motion pair to detect the joint position, which effectively improves the joint control accuracy. The multiple-layer kinematics models among the actuation space, joint space and task space are established, and the motion equations of the antagonistic elbow joint and the coupled wrist joint are further derived, which simplifies the motion transfer relationship between different space and improves the transmission accuracy and efficiency. The equivalent stiffness of the manipulator joint is calculated, and the stiffness characteristics under different joint angles are analyzed. Finally, the performance tests of the prototype, such as joint stiffness test, end precision test, and load test, are carried out. The experimental results show that the designed cable-driven 7-DOF anthropomorphic manipulator has the characteristics of dexterous movement, high positioning accuracy and high stiffness.

Key words: cable-driven redundant manipulator, antagonistic joints, dual encoders, equivalent stiffness