Multi-Joint Actuation of Robotic Arm Using a Switchable Tendon-Sheath Drive System

Wearable upper limb exoskeletons and robot arms have shown great application prospects in both daily life and industrial applications. However, since human arms have many degrees of freedom, these robotic devices usually require a large number of actuators to provide sufficient driving force and flexibility. For most motor-driven robotic arms, this drive requirement typically results in a large, heavy, and costly system. Furthermore, the increase in the number of motors also brings additional energy consumption. To address this, we proposed a switchable tendon-sheath drive system that can achieve multi-joint actuation with only one main drive motor. It uses a tristable clutch to switch the end anchor at the output end of the tendon-sheath mechanism. Based on this actuation system, we developed a two-degree-of-freedom robotic arm platform and a voice control method, and conducted experimental studies to evaluate the multi-joint actuation performance. The experimental results demonstrated that the switchable tendon-sheath system successfully realizes the motion control of the shoulder and elbow joints using a main drive motor, and the self-locking ability of the clutch can effectively maintains the joint posture under variable load conditions.