Master–Slave-Type Gait Training System for Hip Movement Disorders

Robotic devices intended to assist patients recovering from hip movement disorders face two major problems, namely, difficulty in (1) enhancing self-efforts in gait training by only using a robotic device and (2) reproducing a patient's own coordinated motion during gait training. To solve these problems, the authors have developed a gait training device based on the master-slave system. This device treats the user's healthy limbs as the "master" and the paretic limbs for which the user wishes to achieve normal gait motions as the "slave". An inertial measurement unit is used to detect hip joint angular displacements and the time it takes for each displacement to occur; the hip joint angular displacement on the slave side is controlled by a proportional-integral-derivative (PID) controller. Six healthy persons were equipped with the device and asked to walk along a walkway so that their gait motion and the electromyographic activities in their lower limb muscles could be evaluated. The results of that experiment indicate that gait motion was preserved in the simulated paresis in the subjects' hip muscles, which suggests that the proposed master-slavetype gait training device can enhance users' efforts, and that the PID controller controlling angular displacements of the hip joint is able to reproduce natural gait motions.