Hybrid FES orthosis for standing up in paraplegia

Functional Electrical Stimulation (FES) is one of the methods to activate paralyzed muscles for the restoration of functional movements in the patients of spinal cord or central nervous system injury. In the clinical application of FES, the convenience is important as well as safety. Hence, this work combines walker support and orthosis of lower limbs with FES, which is called a hybrid FES. It requires less power of stimulation and it is simple to put pn electrodes comparing with the stand alone FES system. The stimulator applies the constant current stimulus of which rectangular monophasic puluse train is amplitude-modulated. The stimulation is derivered through surface electrodes to quadriceps femoris and gluteus maximus muscles. The control strategy is open-loop, based on the stimulus pattern of standing up motion in nonparalyzed persons, whose electromyogram (EMG) is recorded at standing up motion. The envelope of the amplitude of the surface EMG corresponds to the amplitude of the stimulus current. We set the standard stimulus pattern to the maximal pulse height for each paralyzed persons and then made their own stimulus pattern of a specified paralyzed persons.