Development of a 3-DOF Tendon-Sheath-Driven Upper Limb Exoskeleton with Sliding Mode Admittance Control for Microlaryngoscopic Surgery Assistance

Microlaryngoscopic surgery requires surgeons to maintain elevated arm postures for extended periods, often leading to muscle fatigue, hand tremor, and reduced precision. To address these challenges, this paper presents a tendon-sheath-driven upper-limb exoskeleton (TULE) designed to provide ergonomic support during long-duration procedures. The system provides three degrees of freedom per arm and adopts a simplified dynamic model customized to the characteristic motion patterns of microlaryngoscopic surgery, while employing a hybrid control strategy that integrates admittance control with computed-torque sliding-mode control. Simulations and hardware experiments demonstrate that the proposed controller substantially reduces joint tracking errors compared with PID control, while maintaining smooth torque output. Motion-following experiments further confirm that the exoskeleton achieves compliant human–robot interaction with low interaction torques, and tremor-suppression tests show a reduction of wrist tremor amplitude by approximately 75–80% in lock mode. These results indicate that the exoskeleton can effectively enhance surgeon endurance and stability in microsurgical applications.