Balanced Motions Realization for a Mechanical Regulators Free and Front-Wheel Drive Bicycle Robot Under Zero Forward Speed

This paper focuses on a mechanical regulator free and front‐ wheel drive bicycle robot. We present a scheme to achieve the robotʹs track‐stand motion and circular motion under zero forward speed. In a situation where the robotʹs front‐bar is locked at 90 degrees, a kinetic constraint about the rotating rate of the front‐wheel and the yawing rate of the frame is derived. Using the constraint as a basis, we developed a simplified model of two independent velocities for the robot. The model suggests there is an under‐ actuated rolling angle in the system. Our control strategy originates from the under‐ actuated characteristics of the robot system. Concretely, we linearize the rolling angle of the frame and set the bicycle robot to regulate its tilting by rotating the front‐wheel. In the track‐stand motion, we control the position and the rotational rate of the front‐wheel; but in the circular motion, only the rotational rate of the front‐wheel is strictly regulated. Both simulations and physical experiments results show that our strategy is effective for achieving these two motions.