Tendon-Driven Compliant Prosthetic Wrist Consisting of Three Rows Based on the Concept of Tensegrity Structure

One degree-of-freedom (DoF) virtual rolling-contact joint for the prosthetic wrist is proposed in this letter. For prosthetic wrists, the wrist mechanism should basically be lightweight and have a wide range of motion (RoM). In addition, it is desirable to have compliant characteristics to protect amputees or prosthetics from unexpected external forces. The design of the proposed wrist is based on the concept of tensegrity structure which is similar to ligamentous structure combined with bones and ligaments so that it has compliant and lightweight properties. Actually, the proposed mechanism structurally mimics three rows of the human wrist. Since these three rows move simultaneously and create a single degree-of-freedom in flexion and extension, the proposed wrist covers a wide RoM without any interference between the links, which is similar to the RoM of human wrist. The inherent compliant features of the proposed wrist are validated through experiments.