Adaptive Fuzzy Hierarchical Sliding Mode Control for Ball Segway

This paper proposes an adaptive fuzzy hierarchical sliding mode controller (AFHSMC) for a ball segway. A ballbot-type personal carrier robot, the ball segway is a nonlinear, under-actuated system. As a challenge in control problems, this robot follows a desired trajectory while remaining balanced. The dynamic model of the ball segway is built from the Euler-Lagrange equation. The proposed controller is designed using the hierarchical sliding mode control (HSMC) method. In addition, the controller's parameters are adjusted to compensate for model errors and external disturbances via the Sugano fuzzy model. The stability of the closed-loop control system for the ball segway is also analyzed according to Lyapunov criteria. Simulation results demonstrate the effectiveness of the proposed approach, such as exact robot movements and minor body tilt angles. Moreover, the proposed method yields significantly better results than the previous HSMC method.