Sky-Hook Suspension control of a quadruped walking vehicle

This paper discusses foot force control of a quadruped walking vehicle on rough terrain. The proposed control algorithm has two parts. One is a feedforward control to produce a smooth touch-down and lift-up motion of the leg. The other part is a feedback control to maintain the body´s posture under the conditions of some disturbances. A command force of the feedforward control is calculated beforehand from the data of the body´s position, its acceleration and leg positions. The force increases smoothly from zero after touch-down on the ground, and it decreases smoothly to zero before lift-up. On the other hand, a command force of the feedback control is calculated from the data of the body´s posture measured by gyroscopes. The effect of the feedback control is as if the body is suspended to an absolute frame by springs and dampers. Therefore, it is called `Sky-Hook Suspension´. By this control-algorithm the experimental vehicle TITAN VI is able to walk smoothly on a rough terrain