Coaxial Integrated Tendon-Driven Actuator: Design, Modeling, Control, and Performance Analysis

In this letter, a novel tendon-driven actuator is presented for anthropomimetic robots, mimicking the functionality of a spindle muscle. This actuator can contract and relax, and its tension output can be measured and controlled. The proposed actuator features an innovative space-saving co-axial winding mechanism and an integrated tension feedback sensor. Furthermore, the actuator incorporates an integrated controller and motor driving circuit, powered by a brushless direct current motor. A custom-designed sensor comprising four load cells is employed to measure tension in the tendon, and a closed-loop tension control method is proposed and validated. Tests, including evaluations of dynamic performance and transient response, are conducted on a custom-built test bench to verify the feasibility and efficacy of the proposed design. The test results indicate that the proposed actuator is capable of producing a maximum tendon tension of 300 N with a power density of 0.92 W/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup>, while also facilitating the realization of backdrivability through closed-loop tension control.