Locomotion and Control of a Friction-Driven Tripedal Robot

This letter considers control of a radially symmetric tripedal friction-driven robot. The robot features 3 servo motors mounted on a 3-D printed chassis 7 cm from the center of mass and separated 120 degrees. These motors drive limbs, which impart frictional reactive forces on the body. Experimental observations performed on a uniform friction surface validated a mathematical model for robot motion. This model was used to create a gait map, which features instantaneous omni-directional control. We demonstrated line following using live feedback from an overhead tracking camera. Proportional-Integral error compensation performance was compared to a basic position update procedure on a rectangular course. The controller reduced path error by approximately $46\%$. The error compensator is also able to correct for aerodynamic disturbances generated by a high-volume industrial fan with a mean flow speed of $5.5ms^{-1}$, reducing path error by $65\%$ relative to the basic position update procedure.