Development a fuzzy PID controller for a parallel cable robot with flexible cables

Abstract

Dynamic modeling and control of planar parallel cable robot with considering elastic and inertia effects of cables and pulley dynamic consideration in final equation of motion is calculated in this paper. In this paper, planar parallel cable robot has four cables, demonstrate one degree of actuation redundancy. More perfect dynamic equation of cable robot is derived that contains end-effector, cable, and pulley dynamics that does not be seen completely in other researcher works. In this equation and with considering other researcher works, cables are considered as linear axial springs. Elastic and inertia effects of cables in open loop and closed loop response of the system is studied. Feedback linearization and Ziegler-Nichols method are used for designing closed loop control system. Online dynamic minimum torque estimation is used that all cable tensions be positive during the motion. Two cases are studied. In case 1, dynamic equation of planar parallel cable robot is derived without considering elastic and inertia effects of cables and in case 2, total dynamic equation is driven with considering elastic and inertia effects of cables. Two control systems are designed for robot, PID control system, and fuzzy PID control system for tuning gains to be more robust at encounter of disturbances and parameter uncertainties. System responses show that fuzzy PID controller is more robust than PID controller at encounter of disturbances. For validation of derived dynamic equation without considering cable effects, planar parallel robot is modeled with Adams software and responses derived from MATLAB and Adams software comprised together. Responses of two systems were much closed together.