Control of Lateral Bounding for a Pendulum Driven Hopping Robot

In this paper a novel hopping robot is introduced that uses inverse pendulum dynamics to induce several different gaits. Its mechanical structure consists of a rigid inverted T-shape mounted on four compliant feet. An upright “T” structure is connected to this by a rotary joint. The horizontal beam of the upright “T” is connected to the vertical beam by a second rotary joint. Using this two degree of freedom mechanical structure, the robot is able to perform lateral bounding in addition to hopping forward, reversing direction and turning. Here, the control of lateral bounding is investigated and experimentally tested. The results show that two unique limit cycles exist for lateral motion. Ipsilateral bounding, in the same direction as upper body motion, is fast but unstable and could be used for emergency situations. Contralateral bounding, on the other hand, is stable and robust, and can be viable for practical long-range applications on uneven terrain. The characteristics and control of these two modes of locomotion are explored in this paper.