Mechanism and Position Tracking Control of a Robotic Manipulator Actuated by the Tendon-Sheath

Abstract

To achieve a manipulator that is lighter and more anthropomorphic, a 7-DOF robotic manipulator driven by the tendon-sheath is designed. Its mechanical system and control system are both introduced in this paper. An encoder is installed on both the driver side and the joint side to realize double closed-loop control. Considering the transmission characteristics of the reducer and the tendon-sheath, a position transmission model of a single joint is constructed. Furthermore, the correctness of the transmission model is verified based on the prototype joint four. A proportional-integral-differential (PID) controller and fuzzy PID controller with time-delay estimation (TDE) are designed based on double encoders, and some experiments on the position tracking control are carried out for the robotic joints. The experimental results show that each joint can rotate normally and there is no interference between the different tendon-sheaths. When the drive motor moves to follow the position command of the sinusoidal signal, the TDE-based fuzzy PID controller can reduce the maximum tracking error compared with the traditional PID controller. According to the experimental results, it is feasible to apply the tendon-sheath transmission to the manipulator, which provides a reference for the development of other equipment based on the tendon-sheath.