0
TECHNICAL PAPERS

The Effect of Leg Specialization in a Biomimetic Hexapedal Running Robot

[+] Author and Article Information
Jonathan E. Clark

Department of ESE, University of Pennsylvania, Philadelphia, PA 19104jonclark@seas.upenn.edu

Mark R. Cutkosky

Department of Mechanical Engineering, Stanford University, Stanford, CA 94305

The interested reader can view a clip of the high-speed video (250framess) superimposed on the animated model at the following URL: http://dart.stanford.edu:88/Get/File-442/blenḏlight.mov.

J. Dyn. Sys., Meas., Control 128(1), 26-35 (Dec 01, 2005) (10 pages) doi:10.1115/1.2168477 History: Received April 01, 2005; Revised December 01, 2005

The biologically inspired Sprawl family of hexapedal robots has shown that fast and stable running is possible with only open-loop control. Proper design of the passively self-stabilizing leg structure has enabled these robots to run at speeds of up to 15 bodylengths/s and over uneven terrain. Unlike other running robots built to date, the Sprawl robots’ front and rear legs are designed to preform distinct functional roles. Like the cockroaches that inspired them, the front legs of the robots act to lift and decelerate, while the rear legs provide the primary forward thrust. This paper uses a dynamic simulation to investigate the effect that changing the robot’s leg structure and posture has on its performance. The simulation results support our hypothesis that the use of a differential leg function induced through postural adjustments effectively trades efficiency for stability.

FIGURES IN THIS ARTICLE
<>
Copyright © 2006 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Functional design principles adapted from biomechanical analysis of running cockroaches

Grahic Jump Location
Figure 2

(A) Overview of the hop model and (B) the step deflection response for both the robot leg and the model

Grahic Jump Location
Figure 3

A comparison of the pressure rise and ground reaction force for (A) the robot leg and (B) model

Grahic Jump Location
Figure 4

Ground reaction forces for each leg of the robot and the model

Grahic Jump Location
Figure 5

Effect of leg angle on the velocity of Outdoor Sprawl. Each grid location represents a different nominal configuration of the robot. Each point is where the lines of action of the legs intersect. The circle radius at each point is proportional to the velocity at that configuration. The shaded area represents the unstable operating regime.

Grahic Jump Location
Figure 6

Effect of altering hip stiffness on velocity for a range of leg angles: (A) for the softest hips tested, (B) for optimal stiffness selected in Sec. 5, and (C) for the stiffest value tested. (D) Shows the peak velocity for all configurations at each level of stiffness tested, (E) shows the fraction of the tested configurations at each stiffness that resulted in fast, period-1 running.

Grahic Jump Location
Figure 7

Effect of leg configuration on the model’s velocity (A) and the on band of slopes that it can traverse (B)

Grahic Jump Location
Figure 8

Effect of leg configuration on fore-aft (A) and pitch (B) perturbation settling times

Grahic Jump Location
Figure 9

Comparison of the effect of leg posture for four different stability measures considered in this chapter. The circles represent the velocity at stable configurations.

Grahic Jump Location
Figure 10

Whole body and individual leg ground reaction forces for the Narrow and Sprawled configurations of the model

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In