The simulation of tiptoe mechanism for biped robots

The joints of biped robots generally are fewer than that of the human. As parts which are related to the human gait, the tiptoe mechanism is included among the abbreviated joints. The mammal is categorized into the plantigrade, the unguligrade and the digitigrade by using a footmark and a walk function. The human belongs to the plantigrade, and walks like a monkey or a bear by adapting to a ground from a toe to a heel. From this adaptive walk, its stability is excellent although this gait is not suitable for a quick walk. To improve a turning capability and run swiftly, the other mammals - are categorized into the unguligrade or the digitigrade - are reducing a landing area of soles by atrophying fingers and toes and landing on a ground by fingertips and toes. Moreover, these are employing a quadrupedalism for keeping its stability. On the other hand, the current biped robots take widely a landing area of their soles, to give the stability top priority. Therefore, their feet do not have a tiptoe mechanism, and the gait of biped robots is not achieving a turning capability and quickness like the human. In this paper, as the first step, the tiptoe mechanism is introduced to feet of biped robots with a goal of realizing a turning capability and quickness like the human. Via the multi-body dynamics analysis, we confirmed that a stable gait by adding a tiptoe mechanism is obtained with kinetic energy smaller than a simple gait of the general biped robot.