Control of a tube crawling machine

Abstract

The project of an eight legged pipe crawling robot is presented. First the mechanical design is described with particular emphasis on the sensors and actuators of the robot. These provide the input to the nonlinear controller that is organized hierarchically. According to the mechanical structure of the system, the control task is distributed to a central level, controlling the overall system behavior and a decentral level, corresponding to the individual legs. Both on the central and on the decentral level, the control problem covers coordinative tasks, concerning the sequence of phases in the gait pattern and operative tasks, concerning the control of the forces during each phase of the gait. On the central level, the forces are controlled based on linear theory and distributed to the legs. According to the demands of the overall system, the decentral controllers are designed to adjust the forces of each leg employing the method of feedback linearization.