GALLOPING IN AN UNDERACTUATED QUADRUPEDAL ROBOT
James Andrew Smith
Keywords
Quadruped, legged robot, galloping, rotary gallop, running
Abstract
A series of experiments and simulations are presented here that provide insight into how an underactuated quadrupedal robot can gallop in a controlled manner simply by controlling touchdown and liftoff angles of the legs. Initial work resulted in a rotary gallop with significant yaw. On that basis, two hypotheses are presented and
validated here to yield straight-line galloping. The first hypothesis is that the yaw can be controlled by adjusting the liftoff angle of a rear leg – specifically, the rear leg found on the inside radius of the turn. However, it is not guaranteed that the resulting gait will remain a gallop. Based on the validation of this first hypothesis and,
having observed that animals can gallop in straight lines, a second hypothesis is put forward that, upon finding an initial stable gallop gait with non-negligible yaw, if sequential adjustments are made to both the touchdown and liftoff angles then it will be possible to zero the yaw while also providing for sufficient phase difference
between successive toe contacts to classify the gait as a gallop. The hypotheses are confirmed with experiments showing a repeatable straightened gallop at 0.7 m/s.
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