Nonlinear sliding-mode control for motion of a spherical robot

In order to research the problem about the motion control of a spherical robot, using the constrained Lagrangian method the motion models with uncertainty items are developed, and the motion control strategies, including the lateral attitude controller and longitudinal velocity controller, are designed based on the nonlinear sliding-mode control method. Both controllers guarantee convergence of the controlled states to the desired neighborhood. Then, the structure and composition of the control system is described and analyzed in detail. For the purpose of the real-time and accurately measuring the motion states of the spherical robot, the arc odometer model and line odometer model are developed under the condition of the nonholonomic motion constrain, respectively. Moreover, in order to verify the effectiveness of the presented strategies, the position control experiment of the spherical robot is introduced based on the path follow controller and the robust controllers presented in this paper. The experimental results show that the presented simplified motion model and motion control strategies based on the sliding-mode control method are feasible.