Adaptive Path Following of Underactuated Snake Robot on Unknown and Varied Frictions Ground: Theory and Validations

Abstract

This letter investigates the straight path following problem for a class of underactuated bioinspired snake robots on ground with unknown and varied friction coefficients. Existing works usually design control input requiring the exact values of these friction coefficients, which however rely on the specific operating terrain and may not always be known a priori. By virtue of backstepping technique, we present a novel adaptive controller that can perform the path following tasks and meanwhile it can compensate for unknown and varied friction coefficients in real time. Moreover, it is proved via LaSalle-Yoshizawa theorem that the path following errors converge to zero asymptotically and all the parameter estimates are bounded. Simulations and experiments on an eight-link snake robot are carried out to demonstrate the effectiveness of the proposed control strategy.