The purpose of this study was to develop the robotic gait orthosis using two-joint-muscle model. The concept of two joint muscles applied to this orthosis is similar to actual human skeletal muscle system. The air actuator that is high safety was utilized for each joint movement. Six and/or eight rubber tube actuators were used to exert each joint torque of gait orthosis like the actual human muscle. The property of this rubber tube actuator is lightweight and high output power as compared to other electric motor actuator. Therefore, this actuator is easy to attach the frame of gait orthosis, and to control the joint stiffness. It is effective to maintain a static posture against some external forces.
