Finite-Time Observer-Based Variable Impedance Control of Cable-Driven Continuum Manipulators

Human-robot interaction has been widely studied, where compliant and safe human-robot interaction of continuum manipulators in the constrained environment is one of the key issues that have not been well addressed. In this study, finite-time observer-based variable impedance control of cable-driven continuum manipulators (CDCM) is proposed to overcome the limitation of existing methods. First, the pseudo-rigid modeling method is utilized to establish the kinematics and dynamics of the CDCM. Then, a variable impedance controller with selected controller parameters for the CDCM is designed to realize compliant and safe human-robot interaction operations with force-position coupling constraint, which is rarely studied in the literature. In order to realize the closed-loop variable impedance controller, a finite-time observer is designed to estimate acceleration feedbacks, which can avoid the difficulty of directly sensing the interaction forces and shows excellent robust stability in noisy environments. On this basis, by combining the advantages of the variable impedance controller and finite-time observer, the finite-time observer-based variable impedance controller is proposed, and the stabilities of the proposed method are analyzed. Finally, the feasibility of the proposed control scheme for the CDCM is demonstrated by some numerical simulations.