Design method of non-circular pulleys for pneumatic-driven musculoskeletal robots that generate specific direction force by one-shot valve operations

This paper describes a design method for pneumatic-driven musculoskeletal robots that generate specific direction force. In a dynamic motion, it is often the case that a part of a robot generates specific direction force. Supplying air to muscles contributing to the motion during the motion is desired to realize such motion with discontinuous control system using ON/OFF valves. A mechanism distributing joint torque for each joint is necessary to realize the motion with maximum air supplying. We use a variable moment arm system to distribute joint torque. We propose a design method to determine moment arms of the musculoskeletal systems. In the method, we calculate joint torque that is necessary for a motion and tension of the muscles, and determine moment arms from the joint torque and the tension. In this paper, we developed a one legged jumping robot using non-circular pulleys based on the design method, and verified that the robot generated force as designed.