Mechanism and Control of a One-Actuator Mobile Robot Incorporating a Torque Limiter

This study presents a novel mechanism for the control of a wheeled robot maneuvering with a single actuator. Elements of snakeboard and two-wheeled skateboard propulsion are applied to the design. Two passive wheels, i.e., casters whose orientation can be controlled, are attached in the back and front of the robot body, and a rotor rotates above the body to induce body propulsion using its counter torque. Three degrees of freedom of motion, i.e., the orientation of the rotor and each of the two casters, are mechanically coupled to the single actuator via a torque limiter. The stoppers are set to restrict the angle of the caster orientation, and a torque limiter allows the rotor to continue rotating without being affected by the stopper’s restriction to the range of motion. Experiments demonstrate that the sinusoidal rotor rotation can propel this robot forward and that adding the increasing or decreasing offset to the sinusoidal rotor rotation can curve the robot’s motion. Next, a method to position the robot at a specified goal position is proposed, assuming that the current position of the robot is detectable in every control cycle. This method adjusts the rate of increase or decrease of the offset in sinusoidal rotor rotation depending on the direction of the goal position. Introducing the motion capture system enables the robot to successfully reach the specified goal positions.