A Modular Lockable Mechanism for Tendon-Driven Robots: Design, Modeling and Characterization

Surgical robots with variable stiffness can provide more stable configurations during minimally-invasive surgery.This letter presents a new design of modular lockable mechanism which can be used to change the stiffness of tendon-driven surgical robots. Locking and unlocking are simply actuated by pulling one tendon, and each mechanism has several fixed locking angles on the joint. Consisting of this modular mechanism, a tendon-driven robot has a larger workspace and the variable stiffness. The robot shape can be maintained by the modular mechanisms rather than continuous external input. Both kinematic and shape compensation models of the robot have also been proposed. Results from simulations and experiments on the prototype have validated the locking capability of the proposed mechanism and the accuracy of the proposed models of the modular tendon-driven robots.