Basic Study of Quadruped Locomotion System with Ability to Adjust Compliance
Akihito Sano*, Junji Furusho* and Akihiro Hashiguchi**
*Department of Mechanical and Control Engineering, The University of Electro-Communications, 1-5-1, Chofugaoka, Chofu, Tokyo 182, Japan
**Fuji Photo Film Co., Ltd., 798, Miyanodai, Ashigarakami-gun, Kanagawa, 258 Japan
It is very important to adjust the dynamics of a robot in order to achieve a natural behavior under the complicated interaction between the robot and the external environment. With respect to dynamic walking control of the quadruped locomotion system, a compliance control is discussed. In this paper, the stiffness and dumping of tiptoe motion in the coordinate fixed on the body is controlled at each configuration of the leg. The hierarchical control structure is adopted. In the lower level, torque feedback control at each joint is executed by using a torque sensor which was developed to accurately measure the torque of the joint. In the upper level, the reference torque signal to the lower level is generated to realize the desired compliance. The compliance control is applied in the three-leg-supporting phase and in the touchdown of the swing leg. The desired compliance is designed to absorb the vibration caused by the collision at the touchdown and not to prevent the forward movement. The effectiveness of the proposed control strategy is confirmed by experiments using walking robot “COLT 3”.