Locomotion and Control of a Friction-Driven Tripedal Robot

Hermes, Mark; McLaughlin, Taylor; Luhar, Mitul; Nguyen, Quan

doi:10.1109/icra48506.2021.9561184

Cited by 2 publications

(3 citation statements)

References 21 publications

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“…Several recent efforts have considered the development of radially symmetric robots. Our previous work describing the development of the tripedal test system used in this study showed that the radially symmetric arrangement is controllable using an omnidirectional gait map Hermes et al (2021). This prior effort also highlighted an advantage of being able to define arbitrary lead limbs for radially symmetric robots: sharp path curves can easily be followed.…”

Section: Introductionmentioning

confidence: 78%

“…The ability to move along prescribed curves, rotate in place, and travel in a straight line establishes a framework for future motion planning efforts for radially-symmetric crawling robots. Using the models developed in this paper, we have successfully demonstrated path following for this robot using image-based feedback control Hermes et al (2021). The primary advantage of radial symmetries highlighted in this work is the omni-directional translation ability.…”

Section: Discussionmentioning

confidence: 98%

“…The friction coefficients measured were μ = 0.33±0.012 for the polymer-paper contact and μ = 0.85±0.043 for the sandpaper-paper contact. As described in Hermes et al (2021), these values were obtained by releasing a known mass (with appropriate contacts) from rest down a slope and measuring the velocity achieved by the mass after a set distance. The difference between the initial gravitational potential energy and the final kinetic energy of the sliding mass was attributed to friction, and friction coefficients were estimated from this frictional loss.…”

Section: Robot Design and Characterizationmentioning

confidence: 99%

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Frictional Locomotion of a Radially Symmetric Tripedal Robot

Hermes

Luhar

2023

J Nonlinear Sci

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This study seeks to provide physical insight into the friction-driven crawling locomotion of systems with radially symmetric bodies. Laboratory experiments with a tripedal robot show that both translation and rotation can be achieved with just three independently actuated rigid limbs, i.e., with 3 degrees-of-freedom. These observations are rationalized using a simple mathematical model, which assumes that the friction at each limb is linearly proportional to the normal force at the contact point, and opposes the direction of motion. This dynamic model reproduces experimental observations across an extensive parametric sweep involving sinusoidal rotation of the limbs with varying amplitudes and phase shifts. Model predictions highlight the role played by time-varying normal forces at the contact points. These predictions are confirmed using embedded force transducers in the limbs. We present a further simplified analysis explaining that a geometric nonlinearity is induced in the dynamics from the radial symmetry and that this nonlinearity is essential to the generation of pure translation. We also show that this nonlinearity can be amplified by a cyclic time-varying limb length variation. These results provide a framework for further study of radially symmetric movers.