An experimental study of pseudo passive walking robot-discussions about control parameters and expansion to flexible shoe system

For realization of medical, nursing and home-use robots, energetic efficiency must be improved more and more. Therefore, the authors' group has extended the idea of passive walking from slope to flat floor, using a small power actuator. They call this walking system the pseudo passive walking robot (PPWR). Besides, they analyze the manner of passive walking system with variable leg length. They confirm that leg length control works as an ankle joint torque input. Based on this study, an experimental system PPWR-II, II-R, III can be developed and realizes stable passive walking on flat floor. They examined various parameters on this experiment. The weight balance of the robot, parameters on leg length control, energy consumption and so on. They found that careful tuning of these parameters provides good reduction of walking energy consumption. In addition to these basic studies of PPWR, they consider the expansion of flexible shoe system. This system provides two functions. One is torque assist function equivalent to arc-shape foot. The other is stabilization function on non walking phase. This flexible shoe system can be made with split shoe with spring elements. Equivalent conditions can be introduced using the above analysis of passive walking with arc-shape foot. Based on this condition, they made a split shoe system, and realized passive walking on flat floor similar to the above experiment.