Adaptive Vibration Control of a Flexible Cable Driven Parallel Robot

Abstract

A cable-driven parallel robot (CDPR) possesses significant advantages over common rigid-link mechanisms including: large workspace, low inertia, small size actuators, and high speed motion. However, CDPRs have considerable restrictions consist of: holding tension in all cables, cables axial flexibility, and mechanism low rigidity resulting in mechanism undesired vibrations. In majority of previous studies related to redundant CDPRs control, the cables’ flexibility is assumed negligible and redundancy problem is solved regardless of mechanism stiffness. Vibration control of a new flexible redundant kinematically-constrained CDPR with warehousing applications is studied in this research. In proposed methods, for minimization of undesired vibrations, the CDPR redundancy problem is solved based on maximizing its stiffness. Proposed controllers are designed based on linear methods of pole placement and also linear quadratic regulation (LQR) technique. Transforming the designed controllers to adaptive ones has shown performance improvements in case of moving platform mass and inertia uncertainty. Simulations results show robustness and high performance of designed controllers beside practicality of the inputs.