Undulatory Locomotion

What is it?


An alternative to locomotion by legs, by actuated wheels or by actuated tracks.
A ``snake-like'' locomotion paradigm.

What's the idea?


Take a multi-degree-of-freedom body whose shape can be made to vary in a controlled way. Vary its shape periodically. In the presence of some form of interaction of the body with its environment, this CAN give rise to global motion (as opposed to in-place oscillation of the system).

Biological examples?


Locomotion of snakes, worms, paramecia, fish, ...
The falling cat.
Ice skaters.
Snakeboard riders. Roller Racer riders.

So, what happens?


Take the Roller Racer: The wheels specify a particular form of interaction of the articulated body with its supporting plane, that can be modelled by so-called nonholonomic constraints. If the front wheel assembly is made to oscillate periodically around the vertical pivot, the system can be seen to move! The wheels are not directly actuated. The motion of the system is due to the periodic shape variation and to the nonholonomic constraints.

What's the big deal?


Man-made systems whose motion is related to these ideas:
Orbiting satellites equipped with manipulator arms.
Minimally-invasive surgery tools (e.g. self-propelling endoscopes).
Ultrasonic motors.
One of the goals of this line of research: A general theory of locomotion.

Examples of such systems:


G-Snakes


o SE(2)-Snakes: Nonholonomic Variable Geometry Truss Assemblies
o A two-node SE(2)-Snake: The Roller Racer

Snakeboard

Snake-like/Hyper-Redundant Locomotors


Who is working on Undulatory Locomotion?


o Prof. Joel Burdick's group at Caltech
o Prof. P.S. Krishnaprasad's group at the University of Maryland
o Prof. Shigeo Hirose's group at the Tokyo Institute of Technology

Please send comments to tsakiris@ics.forth.gr.
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