Design of a Novel Surgical Robot with Rigidity-Adjustable Joints based on Time-Division Multiplexing Actuation

Tendon-driven robots are commonly used in minimally invasive surgery (MIS) due to its small size, high dexterity and great controllability. However, there is a general tradeoff between miniaturization and dexterity of a tendon-driven robot, due to the large number of tendons required to actuate a multi-degree-of-freedom (multi-DoF) robotic motion. This work presents a novel design of robot that employs only one pair of tendons to actuate multiple rigidity-adjustable joints via a time-division multiplexing actuation method. The joints can be locked and unlocked by a fast-response and power-saving mini-solenoid clutch mechanism, and the accumulated actuation of the unlocked joints at each time yields a multi-DoF robotic motion. Experiments on a two-DoF robot prototype show that joint motions under the tendon actuation are well decoupled and have high repeatability in a wide range of angles. The results indicate that this method can be used to develop miniature and dexterous surgical robots with high control speed and accuracy.