Attitude Control of a Quadruped Trot While Turning

During a complete running stride, which involves significant periods of flight during which no legs are contacting the ground, a quadruped cannot employ static stability techniques. Instead, the corrective forces necessary to maintain dynamic stability must be applied during the short stance intervals inherent to high-speed running. Because of this complexity and the large coupled forces required to run, much of the research on the control of quadruped running has focused on planar systems which are not required to simultaneously control attitude in all three dimensions. The 3D trot controller presented here overcomes these and other complexities to control a trot up to 3.75 m/s, approximately 3 body lengths per second, and turning rates up to 20 deg/s. The biomimetic method of banking into a high-speed turn is also investigated here. Along with the details of the attitude control algorithm, a set of control principles for high-speed legged motion is presented. These principles, such as the need to counteract the disturbance of swing leg return and the usefulness of force redistribution during stance, are not dependent on a particular scale or actuation scheme and can be applied to a wider range of legged systems