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Volume 27 Issue 5 - Publication Date: 1 May 2008
 
Legless Locomotion: A Novel Locomotion Technique for Legged Robots
 
Ravi Balasubramanian Computer Science and Engineering, University of Washington, Box 352350, Seattle, WA 98195-2350, USA, Alfred A. Rizzi Boston Dynamics, 614 Massachusetts Avenue, Cambridge, MA 02139, USA and Matthew T. Mason Robotics Institute, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213-3890, USA
 
We present a novel locomotion strategy called legless locomotion that allows a round-bodied legged robot to locomote approximately when it is high-centered. Typically, a high-centered robot is stuck since the robot’s legs do not touch the ground. Legless locomotion uses the legs as a reaction mass to set up oscillatory body rotations which when coupled with ground contact gradually translate the robot. Legless locomotion’s continuous dynamics differs from previously studied locomotion methods because of the simultaneous interaction of gravityinduced oscillations, a configuration-dependent system inertia, and non-holonomic contact constraints. This paper employs simple models to capture the complex dynamics and uses the intuition developed from the models to develop gaits that provide planar accessibility. We also present a quantification of legless locomotion’s properties using simulations and motion-capture experiments.
 
Multimedia Key
= Video = Data = Code = Image
 
Extension
Type
Description
1
Example 1: RHex escapes after becoming highcentered. (2.31 MB) mp4
2
Example 2: A round-bottomed RHex locomotes by swinging its legs. (8.94 MB) mp4
3
Example 3: A simulation of the sphere–plane contact kinematics illustrates a sphere can translate in any direction using roll, pitch, and yaw oscillations. (1.96 MB) mp4
4
Example 4: Experiment showing RRRobot locomoting sideways. (3.26 MB) mp4
5
Example 5: Simulation showing RRRobot locomoting sideways. (8.87 MB) mp4
6
Example 6: Experiment showing RRRobot locomoting in a counter-clockwise path. (8.89 MB) mp4
7
Example 7: Simulation showing RRRobot locomoting in a counter-clockwise path. (14.4 MB) mp4
8
Example 8: Animation of experiment motion capture showing legless locomotion gait transitions. (7.17 MB) mp4
 
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