Dynamic control of a quadruped robot based on free movement in a gravity field

It is generally recognized that cursorial animals possess off-road mobility characteristics far superior to those of conventional wheeled or tracked vehicles. In this paper, a control method for speedy quadruped locomotion is presented which is based on free movement in a gravity field and saves energy. In the supporting phase, the waist joints are under an open-loop control which consists of two control modes: 1) a free rotation mode and 2) a constant voltage mode. The stability of the proposed method is examined by numerical analysis. The walking robot 'COLT-1' is able to achieve average speed of 0.5 m/s by using this control method. (author)