I . Design principle of the interaction with the environment
  We humans control the body compliance so as to realize desired behavior, which seems a key to realize adaptive motor skills. Based on such an idea, we try to derive a design principle of an intelligent robot that can realize adaptive behavior by utilizing pneumatic artificial muscles. Antagonistic drive of pneumatic muscles can realize joint compliance with little time-delay along with a simple control scheme. Biological mechanisms such as antagonistic drives and bi-articular muscles will enable us to build adaptive biped robots. A pneumatic actuator can generate explosive power, which is also an advantage over the conventional electric motors for the dynamic locomotion.
  Although the shape of a conventional humanoid robot is designed similar to that of a human, its dynamics is completely different. The biped robot built by this project has similar driving mechanism as a human. Therefore, its dynamics is expected to be similar to that of a human, and as a result, we can expect that dynamics of the biped robot is subject to the same principle that a human is subject to. We can derive such a principle through experiments with the biped robots.