Adaptive Control of a Spatial 3-Degree-of-Freedom Cable-Driven Parallel Robot with Kinematic and Dynamic Uncertainties

Abstract

This paper addresses the problems of model uncertainties and tension restraints in a spatial 3-degree-of-freedom (3-DOF) cable-driven parallel robot, a novel adaptive control (AC) scheme is designed to handle the kinematic and dynamic uncertainties simultaneously, regulate the tension in 4 cables, and perform high-precision tracking tasks. The linear expressions of kinematic and dynamic models are derived, based on which the adaptation laws are proposed through gradient descent method. A tension distribution algorithm is considered to keep all the cables in tension as well. By applying Lyapunov stability theory, the convergence properties of the cable length tracking errors and the ultimate boundedness of the estimated kinematic and dynamic parameters are guaranteed. Trajectory tracking experiments with a spatial 3-DOF CDPR are presented. It is shown that compared with classical augmented PD (APD) scheme, the proposed AC scheme can effectively enhance the tracking accuracy by correction of model parameters, and eventually have an improved performance of the mobile platform.