High-Speed Sliding Locomotion Generation on Slippery Surface of an Indirectly Controlled Robot With Viscoelastic Body

Towards achieving stable and high performance locomotion on a slippery ground, underactuated sliding locomotion robots have been proposed in our previous studies. Unlike walking robots stepping with legs, this legless robot generates sliding locomotion on a slippery road surface by means of its body rotation, which is indirectly controlled by an active wobbling mass via entrainment effect. To concentrate the sliding directions towards forward movement as well as to excite the propulsive force at the underactuated grounding point, a viscoelastic body, which contains spring and damper, is applied to the new model in this letter. First, we derive the equations for generating the sliding locomotion and the mechanism for its indirect control. Second, typical sliding locomotions are generated via numerical simulations. In addition, stick diagram of the locomotion is shown, where limit cycle is obtained from the phase-plane plot. The results show that the sliding velocity is extremely increased by the new model. Third, the effects of damping and spring on the locomotion pattern are analyzed from the energy consumption point of view and the parametric study, respectively. Finally, with the existence of body rotation, spring oscillation, and active wobbling motion and by considering all of them as nonlinear oscillators, we conduct nonlinear analysis to deepen our understanding of the detailed locomotion dynamics.