Modeling and Robust Control for Tendon-Sheath Artificial Muscle System Twist With Time-Varying Parameters and Input Constraints: An Exploratory Research

Tendon-sheath artificial muscle (TSAM) is a type of artificial muscle, which is widely used in robotic flexible endoscopies. The characteristics of the tendon force/position transmission were studied recently, but the control issue of the TSAM twist is still barely concerned. In this article, an effective robust control scheme is proposed for the TSAM twist, which achieves satisfactory tracking performance. First, a rigorous model was developed for the TSAM twist with consideration of parameters uncertainty and actuator input constraints, moreover, the disturbance of the discontinuous friction (Coulomb friction) was analyzed. Next, by applying some signal operation methods, a nonlinear robust controller was designed. In addition, the stability of the control strategy was proven theoretically by utilizing Lyapunov-based theory. Finally, a series of hardware experiments were conducted on a robotic flexible ureteroscope test-bed. The feasibility of the proposed model, the effectiveness and robustness of the designed control method were extensively validated.

Automated summary

This article studies the control issue of the TSAM twist in robotic flexible endoscopies and proposes an effective robust control scheme. The model is rigorously developed and a nonlinear robust controller is designed, with stability proven theoretically. Hardware experiments validate the feasibility, effectiveness, and robustness of the proposed model and control method.