Title: Gait stabilisation of an underactuated bipedal walker on steep slopes

Authors: Surbhi Gupta

Addresses: Academy of Scientific and Innovative Research, CSIR-Central Scientific Instruments Organisation (CSIO), Chandigarh, 160030, India

Abstract: In this paper, we have demonstrated that by using optimised design parameters and appropriate reference trajectory, a bipedal model can be underactuated to stably walk on steep-sloped surfaces. Underactuated bipeds can walk stably on level-ground and slopes of up to 20°. Inspired by mass-distribution in human body, the foot-to-body mass ratio is considered negligible in the mathematical models of these bipeds. We considered this ratio to be non-zero and optimised it along with the leg-length for maximising the distance travelled by the simplest bipedal walking model before falling down. An optimal switching controller was designed to track a reference trajectory as the target gait cycle. This reference trajectory was obtained from the passive dynamics study of the optimised bipedal walker on steep slope instead of from conventional level-ground walking. The controller pushes the gait to the target pattern by switching the control between hip-joint, ankle-joint and no control, as per requirement. The resultant underactuated biped could walk on slopes 0°-30°.

Keywords: bipedal locomotion; underactuation; switched controller; optimal control; hybrid dynamics; nonlinear dynamics.

DOI: 10.1504/IJIEI.2021.10046406

International Journal of Intelligent Engineering Informatics, 2021 Vol.9 No.6, pp.533 - 550

Received: 07 Jan 2021
Accepted: 01 Oct 2021

Published online: 25 Apr 2022 *

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