Intelligent control of a four-rope-driven level-adjustment device with constrained outputs

This paper mainly concerns the intelligent control of a four-rope-driven level-adjustment device with constrained outputs. In the paper, an intelligent controller based on fuzzy systems is designed for the device to adjust eccentric payloads to level and keep the rope´s tension balanced. The controller is composed of two sub-controllers, each of which deals with various situations by choosing different fuzzy rules. As the actuators adopted in the device can only move within a certain range, it is necessary to take their moving ranges into consideration. Actually, each control cycle includes two stages. At the first stage, the controller regulates the payload´s diagonal joined with the constrained actuators. At the second stage, the controller adjusts the other diagonal. If the actuators joined with this diagonal are also constrained, the controller mainly regulates the payload´s posture. Otherwise, the controller regulates the payload´s angle as well as the ropes´ tension simultaneously. Finally, the intelligent controller is used to control the four-rope-driven level-adjustment device, and gets satisfying results.