Composite Motion Control of Cable-Driven Continuum Robots: An Auxiliary-System Based Compensation Method

High-performance motion control of cable-driven continuum robots is challenging due to the inherent model uncertainties, actuator saturation, and measurement delays. Inthis article,we utilize the idea of auxiliary systemto reveal the dynamics of the model uncertainties, actuator saturation, andmeasurement delays, and design a composite motion control strategy to compensate themsimultaneously. First, a time-delay auxiliary system is designed using Pade approximation technique to approximate the saturated time delay, thereby transforming the saturated continuum robot system with time delay into one without time delay. A disturbance auxiliary system and a saturated auxiliary system are also designed to estimate model uncertainties and address actuator saturation, respectively. Second, based on the designed auxiliary systems, a feedback controller is proposed to compensate the model uncertainties, actuator saturation, and measurement delays. The stability of the closed loop system under the proposed control scheme is analyzed as well. Finally, the effectiveness of the proposed control scheme is verified by comparative simulations and experiments.