Development of Pressure Intensifier for Water Hydraulic McKibben Muscles

In rehabilitation field, clean actuators driven by water are required. In particular, water hydraulic McKibben muscles receive remarkable publicity. However, pressure level of tap-water in Japan is not sufficient to drive the actuators. To overcome the problem, a novel pressure intensifier for water hydraulic McKibben muscles is developed. The intensifier is driven by only tap-water and its working principle is based on the difference of pressure receiving area. It consists of six syringes and then four of them are used in inlet side and the others are used in outlet side to make pressure receiving area of inlet side double. In this paper, some static and dynamic experiments for a muscle displacement control system are carried out: 1) to examine a muscle displacement - supply pressure characteristics and a rated intensified pressure of the proposed intensifier as static characteristics, and 2) to investigate a frequency response of the intensifier and a control performance of the whole system as dynamic characteristics. In addition, these characteristics are also examined under some loaded conditions because the characteristics of McKibben muscles is drastically changed by loads connected to the end of the muscles.