Mechanisms and control of under-actuated 4-legged locomotion robot -proposal of walking model by under-actuated system

This paper discusses the possibility to realize both of walking and running at a single robot with the under-actuated legged system, which is made by the combination mechanism of linkages and actuators. The under-actuated system is driven by less numbers of actuator than the numbers of degree of freedom of a system, and therefore it enables to reduce the weight of the robot. This study aims at realizing the 4-legged locomotion by controlling the phase to manipulate the legs made by links which is designed by the under-actuated system. This paper first shows the similarity of walking and running of 4-legged animal, and proposes the way of realizing the both actions by the declination of phase of motion. In order to design the leg mechanism with effective linkage systems, the kinematics simulator was developed and the performance was tested by the prototype.