Development of a flexible tail for legged robot

Some creatures can realize dynamic locomotions with a slender body by utilizing the dynamic effect by moving their whole body besides their legs. For example, some mammals moving by hopping with two legs at high speed and high efficiency have a tail as long as their body length. Their tails are composed of multi-joint and are flexible. The dynamic effect by swinging their flexible tails is useful for fast running and high jumping. In this paper, we develop a flexible tail mechanism for two-legged robot inspired by the flexibility of the animal tail. This tail is comprised of 6 linkages in series and the linkages are connected with elastic passive joints. First, the elasticity of tail joints and the motion of the tail base joint are designed by jumping simulations. To evaluate the effectiveness of the flexible tail mechanism, jumping experiments have been conducted using the prototype of the two-legged robot with the flexible tail as well as rigid tail. The results of these experiments show that the legged robot realized higher jumps with using the effect of swinging its flexible tail.