Wide Area Exploration System Using Passive-Follower Robots Towed by Multiple Winches


J.V. Salazar L.1, M. Hoshi1, Y. Hirata1

1. School of Engineering, Tohoku University, Sendai, 980-8579, Japan

Published in IEEE Robotics and Automation Letters, 5 (2020) 6459 - 6466

DOI: 10.1109/LRA.2020.3013859

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In this study, we propose a wide area exploration system that consists on passive wheeled robots equipped with exploration sensors that are pulled from a high position with wires fed out from two winches. The robots are driven by the pulling force from the winches and they are able to steer by controlling brakes attached to their wheels. By adjusting the wire length, the passive-follower robot is pulled within the exploration area and it controls the braking torque of the wheels to follow a desired trajectory based on its current position. This system has the advantage that it is effective for ground exploration, does not require advanced calibration, and can be installed quickly. In this letter, we first explain the outline of the proposed system. Then, we introduce the hardware design of the developed winches and passive-follower robot. Next, the control method of the winch unit and the passive-follower robots are described. Here, we introduce the feasible braking control region for motion analysis and control of the passive-follower robot. Finally, we apply these control methods to the proposed system and report the results of verification experiments. We describe the feasible range of a follower robot, which changes depending on the position of the winches. We conducted an outdoor experiment, and confirmed the effectiveness of this system by evaluating the trajectories of the passive-follower robot.