Kazuaki Hiramatsu

Robotic gait trainer in water: Development of an underwater gait-training orthosis

Purpose. To develop a robotic gait trainer that can be used in water (RGTW) and achieve repetitive physiological gait patterns to improve the movement dysfunctions. Method. The RGTW is a hip-knee-ankle-foot orthosis with pneumatic actuators; the control software was developed on the basis of the angular motions of the hip and knee joint of a healthy subject as he walked in water. Three-dimensional motions and electromyographic (EMG) activities were recorded in nine healthy subjects to evaluate the efficacy of using the RGTW while walking on a treadmill in water. Results. The device could preserve the angular displacement patterns of the hip and knee and foot trajectories under all experimental conditions. The tibialis anterior EMG activities in the late swing phase and the biceps femoris throughout the stance phase were reduced whose joint torques were assisted by the RGTW while walking on a treadmill in water. Conclusion. Using the RGTW could expect not only the effect of the hydrotherapy but also the standard treadmill gait training, in particular, and may be particularly effective for treating individuals with hip joint movement dysfunction.

Development of Pneumatic Gait Assist System

The aim of this study is to develop a pneumatic gait training system. This study report the prototype of pneumatic gait training system based on a modified long-leg orthosis and a treadmill system. The special pneumatic actuator, the similar actuator to human muscular system, was used as the actuator for hip and knee flexion/extension movement. This prototype system of pneumatic gait training is able to utilize for both land and underwater environments. We evaluated this system by the experimental test on land and underwater conditions. It is indicated from the experiment test that 1) the hip and knee joint movement patterns of both on land and underwater gait were quite similar kinematics for normal gait pattern, 2) the activity of lower limb muscles decreased across the gait cycle on land gait, 3) the activity of hip extensor and knee flexor muscles decreased during stance phase in underwater gait. These results of this study suggest that the pneumatic gait training system might be effective for gait training to several motor disorders.