Energy-efficient Locomotion of Elastic Snake Robots

Abstract

Inspired by nature, elasticities and natural dynamics can be used to improve the locomotion efficiency of robotic systems. Advances in nonlinear normal mode theory have recently provided a new way to characterize natural dynamics in nonlinear robotic systems. Snake-like robots are nonlinear systems that can locomote without the need for hybrid dynamics. This allows easier analysis of their natural dynamics. This thesis investigates if and how the natural dynamics of a kinematic elastic snake robot can be used to design efficient gaits. Two approaches to design gaits based on natural dynamics are presented and compared to elliptical gaits from literature using dynamic simulations and hardware experiments with a self-designed modular snake robot. For gaits generated by switching between two nonlinear normal modes, the simulations show that they do not improve the locomotion efficiency of the robot. Gaits based on non-braking periodic trajectories are ideally efficient in theory, but in the hardware experiments they also do not improve the locomotion efficiency compared to the elliptical gaits. Nevertheless, the investigation reveals promising insights into the design of efficient gaits based on natural dynamics, which will improve further research in this field.