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.

Vibration reduction of Cable-Driven Parallel Robots through elasto-dynamic model-based control

“…Several controllers have been proposed in the literature to improve CDPR accuracy locally or on trajectory tracking [11,12,13]. In [14], the control of CDPR in the operational space is presented while considering non elastic but sagging cables through the Assumed Mode Method.…”

Design Optimization of Redundantly Actuated Cable-Driven Parallel Robots for Automated Warehouse System

“…(10), all components in RW satisfy the inequality in Eq. (11) if and only if (15) which can be further expressed as…”

“…Wang et al [14] minimized the energy consumption of the CDPR in an AWS by optimizing the tension distribution of the cables. But it is difficult to get accurate estimation of the payload weight in AWS [15], and the low cable tension will reduce the out-of-plane stiffness and cause the unexpected vibrations. Jamshidifar et al [16] proposed a robust control method to reduce undesired vibrations of the plannar AWS when keeping the cable tension low.…”

Elasto-dynamic Model-Based Control of Non-redundant Cable-Driven Parallel Robots

“…Thanks to their low inertia, CDPRs can reach high velocities and accelerations in large workspaces [4]. Several controllers have been proposed in the literature to improve CDPR accuracy locally or on trajectory tracking [5], [6], [7]. In [8], the control of CDPR in the operational space is presented, where the CDPR model is derived using Lagrange equations of motion for constrained systems, while considering non elastic but sagging cables through the Assumed Mode Method.…”