Sliding Mode Control of Planar Snake Robot With Uncertainty Using Virtual Holonomic Constraints

In this paper, we present a sliding mode control (SMC) based approach to address the velocity tracking and head-angle control problem of a planar snake robot. The motion characteristics of a snake exhibit the generation of propulsive force as a result of anisotropic friction with respect to the ground. To imitate the motion of a snake, all the joints of the snake robot are tracked to a serpenoid gait function utilizing virtual holonomic constraints. The parameters of the gait function are obtained from the SMC resulting in head-angle control and velocity tracking. SMC has been chosen to ensure robustness and stability of the system in the presence of uncertainties arising from variation in the friction force coefficients between the robot and the ground. Lyapunov's stability analysis proves the finite-time stability of the system. The control scheme has also been verified and compared with an existing approach through simulation studies.