Development of a pneumatic artificial muscle based on biomechanical characteristics

This paper reports the development of a pneumatic artificial muscle based on biomechanical characteristics. A wearable device and a rehabilitation robot which assists a human muscle should have characteristics similar to those of human muscle. In addition, because the wearable device and the rehabilitation robot should be light, an actuator with a high power/weight ratio is needed. At present, the McKibben type is widely used as an artificial muscle, but in fact its physical model is highly nonlinear. Further, the heat and mechanical loss of this actuator are large because of the friction caused by the expansion and contraction of the sleeve. Therefore, the authors have developed an artificial muscle tube in which high strength Kevlar fiber has been built into the silicone tube. However, its contraction rate is smaller than actual biological muscles. In this study, an artificial muscle with a high contraction rate was developed by using natural latex rubber as the tube material. Since the elasticity of this material is smaller than that of silicone, characteristics similar to those of an actual muscle can be expected. Experimental results demonstrate the effectiveness of this artificial muscle regarding its fundamental and biomechanical characteristics.