Passive creeping of a snake-like robot

The control of a snake-like robot is a challenging problem because of the complex dynamics. In this paper, we present a novel method, called passive creeping, to control the serpentine locomotion of the snake-like robot. The kernel of this method is composed of the following two concepts: 1) dynamic shift brings the tendency toward the serpentine locomotion; and 2) energy links the environments and the dynamics with the control law based on passivity. The head module leads the movement, and the body modules push the robot forward. The movement is a dynamic process from an unordered state to an ordered state, and the maximal Lyapunov exponent explicates the orbital stability of the movement in the phase space. Especially, the snake-like robot can adapt to the environments with different friction coefficients according to the dynamic state not the environment information. The validity and adaptability of the method is studied through simulations