Disturbance Compensation Control for Humanoid Robot Hand Driven by Tendon-Sheath Based on Disturbance Observer

Abstract

The operation accuracy of humanoid robot hands driven by the tendon sheath will be reduced due to the influence of friction torque during rotation, which is not conducive to the dexterous operations of humanoid robot hands. In order to improve the control accuracy of humanoid robot hands, this paper proposes a control strategy based on the disturbance observer compensation, which eliminates the external disturbance torque by compensating the friction torque. Firstly, this article proposes the mechanical structure of humanoid robot hands driven by the tendon sheath with 19 degrees of freedom (DOF). This humanoid robot hands can grasp most irregular objects. Next, the dynamic model of humanoid robot hands’ drive systems is established based on the tendon sheath transmission theory. The driving system’s dynamic model reveals the influence of friction torque on the motion accuracy of the humanoid robot hand. Then, the disturbance observer (DOB) is designed based on the robust stability theorem. The DOB is used to improve the control accuracy of the driving system, thereby improving the operational accuracy of humanoid robot hands. Finally, this article conducts simulation rotation tracking control and prototype grasping control experiments on humanoid robot hands. The experimental results show that the proposed control strategy based on disturbance compensation can effectively improve the operational accuracy of humanoid robot hands. Note to Practitioners—This paper proposes a humanoid hand with 19 degrees of freedom based on the tendon-driven theory and applies the cable theory for its dynamic modeling. To address the issue of decreased precision caused by friction in practical operations, a friction compensation control strategy based on disturbance observer is proposed in this study. This control strategy improves the motion accuracy and stability of the mechanical hand. Finally, the effectiveness of the proposed control strategy is demonstrated through numerical simulation and experimental validation.