Path tracking control of a spherical mobile robot

The typical dynamic path following method presents a systematic framework for nonholonomic mobile robot and exhibits excellent tracking performance in simulations and experiments. However, it fails to converge the position and pose simultaneously for spherical robot with a 2 DOFs pendulum. This paper discusses the practical path tracking control of a spherical robot, focusing on the simultaneous converges of position and pose. The kinematics and dynamics models of a spherical robot are deduced and regulated to be a canonical form through the null space method and nonlinear feedback. Under the inspiration of human-like tracker-guide mode, a real-time fuzzy guidance scheme for the path tracking control of the spherical robot is proposed. To deal with the dynamics, a hierarchical sliding mode controller is integrated with the fuzzy guidance scheme through a backstepping strategy. The effectiveness of the proposed path tracking method is validated trough MATLAB simulations on both the comparisons with the typical dynamic path following algorithm and several practical cases: effect of initial conditions, complex curves and piecewise continuous paths tracking.