Point-to-point motion control of a unicycle robot: Design, implementation, and validation

This paper presents the design, implementation, and validation of balance control and point-to-point motion control of a single-wheeled (unicycle) robot. The robot consists of a wheel, a body, a reaction wheel, and a turntable. The wheel is used to move the robot forward and backward to obtain longitudinal stability. The reaction wheel is used for obtaining lateral stability. The turntable provides steering torque about the vertical axis of the robot. The dynamic model of the system is derived using Euler-Lagrange formulation. By retaining the predominant nonlinear terms and neglecting the high-order coupling terms, the system model is simplified to three decoupled systems. Sliding mode control is then used to design the balance and steering controllers for the simplified model. By combining the obtained balance control and steering control, a point-to-point motion control strategy is proposed. The experimental results are presented to verify the effectiveness of the designed control schemes.