Trajectory control of the cable-based parallel mechanism based on dynamics

This paper is concerned with trajectory control system of cable-based parallel mechanisms (CPM) based on dynamics. Firstly, the dynamic formulation of the CPM with non-negligible cable mass was established by means of Newton-Euler formulation. Secondly, considering the inherent characteristics of nonlinearity, slow time-variant, and multivariable coupled system, a decentralized control approach is proposed, and an immune proportional-integral-derivative controller, using fuzzy logic controller as anti-body-suppressed function to improve the self-tuning capability, is developed for each subsystem of the CPM to realize the trajectory tracking of the end-effector. Finally, simulation is performed to validate and highlight properties of the proposed control strategy in the presence of external disturbances.

I. Introduction

The most remarkable point of cable-based parallel mechanism (CPM) is that it uses flexible cables instead of rigid links. The cable-based parallel mechanisms have several advantages over rigid-link mechanisms. Firstly, they can have larger workspaces because their joints can reel out a large amount of cables. Secondly, all of their actuators and transmission systems can be mounted on the fixed base and thus, they have a higher payload-to-weight ratio, which makes them attractive for high-load and high-speed applications. Finally, their special designs make them potentially inexpensive, modular, and very easy to reconfigure.