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Adaptive locomotion on varying ground conditions via a reconfigurable leg length hopper


Sheikh, Farrukh Iqbal; Pfeifer, Rolf (2012). Adaptive locomotion on varying ground conditions via a reconfigurable leg length hopper. In: Azad, A K M; Cowan, N J; Tokhi, M O; Virk, G S; Eastman, R D. Adaptive Mobile Robotics. Baltimore, USA: Climbing and Walking Robots (CLAWAR), 527-535.

Abstract

In this paper, we present the concept of adapting to changes in ground conditions like stiffness, damping and friction, using a novel two degree of freedom reconfigurable leg length hopping robot with a fixed passive compliance. In such a robot, the change in the dynamics of the single legged hopper can be induced by the change in coupled stiffness and damping of the system, i.e., stiffness and damping of the ground coupled with the stiffness and damping of the robotic leg. It is experimentally shown by in-place hopping of a robotic leg on various grounds (stiff, less stiff and soft) that the leg can effectively adapt to changes in coupled stiffness and damping by the rate and the amplitude at which the leg length changes. This is true, while the leg hops in-place as the role of ground friction is negligible. However, in forward motion where the ground friction dominates, a change in initial effective leg length, i.e., shortening or lengthening can provide an additional support to the hip motor in overcoming even large variations in ground friction. This is demonstrated through a planar locomotion experiment on different ground surfaces. The overall results provide strong support for this concept.

In this paper, we present the concept of adapting to changes in ground conditions like stiffness, damping and friction, using a novel two degree of freedom reconfigurable leg length hopping robot with a fixed passive compliance. In such a robot, the change in the dynamics of the single legged hopper can be induced by the change in coupled stiffness and damping of the system, i.e., stiffness and damping of the ground coupled with the stiffness and damping of the robotic leg. It is experimentally shown by in-place hopping of a robotic leg on various grounds (stiff, less stiff and soft) that the leg can effectively adapt to changes in coupled stiffness and damping by the rate and the amplitude at which the leg length changes. This is true, while the leg hops in-place as the role of ground friction is negligible. However, in forward motion where the ground friction dominates, a change in initial effective leg length, i.e., shortening or lengthening can provide an additional support to the hip motor in overcoming even large variations in ground friction. This is demonstrated through a planar locomotion experiment on different ground surfaces. The overall results provide strong support for this concept.

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Additional indexing

Item Type:Book Section, refereed, original work
Communities & Collections:03 Faculty of Economics > Department of Informatics
Dewey Decimal Classification:000 Computer science, knowledge & systems
Language:English
Date:2012
Deposited On:21 Sep 2012 13:33
Last Modified:05 Apr 2016 15:58
Publisher:Climbing and Walking Robots (CLAWAR)
Number of Pages:9
ISBN:978-981-4415-95-8
Additional Information:Proceedings of the 15th International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines
Publisher DOI:https://doi.org/10.1142/9789814415958_0068
Official URL:http://www.worldscientific.com/worldscibooks/10.1142/8546#t=toc
Other Identification Number:merlin-id:7281
Permanent URL: https://doi.org/10.5167/uzh-64799

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