Study on the Application of Model-based Control Algorithm for a Suspended Cable-Driven Parallel Robot

Abstract

This paper introduces a model-based control scheme for controlling the position of a suspended cable-driven parallel robot. The robot is designed to have a fixed frame base with four cables. The cables are attached to winches on one end, driven by stepper motors, and to a moving platform at the other end. The control scheme consists of two systems: the reference model and the implemented control. The implemented control hosts the stepper motor to drive the winch based on the requirements derived from the reference model. The reference model converts the desired Cartesian trajectory into joint spaces, which are then translated into the number of required steps. The number of steps will act as a set point for the stepper motor. Three trajectories are generated to test the compliance of the controller with its position. The error compensation scheme is introduced to increase the positional accuracy of the previous controller, especially on the z-axis. This algorithm uses the nature of discrete stepper motor movement to estimate the actual cable length, which is then fed back to the control system as an error. The control simulation results indicate a significant improvement in control performance, i.e. reduced position error, was achieved.

Keywords

• cable-driven parallel robot (cdpr)
• error compensation
• model-based control
• stepper motor