A template candidate for miniature legged robots in quasi-static motion

The paper introduces the Switching Four-bar Mechanism (sfm), a new low-dimensional kinematic abstraction forminiature legged robots, aimed at quasi-static motion planning in the horizontal plane. The model comprises a rigid torso and four rigid legs which engage in an alternating tetrapod gait. As the gait is executed, the torso and the legs form two switching four-bar linkages, parameterized by the leg touchdown and liftoff angles, as well as the leg angular velocity. We show that the sfm model captures on average experimentally observed behaviors of an eight-leggedminiature robot crawling at low speeds quasi-statically. This work represents a first step toward a template that captures critical aspects of the kinematic behavior of miniature legged robots implementing quasi-static gaits. Such template can be used as a tool to facilitate motion planning tasks with such robots.