Legless Locomotion: A Novel Locomotion Technique for Legged Robots

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. KEY WORDS—legged robots, mobility, dynamics and kinematics.