Design of a symmetry controller for FES cycling - Preliminary re- sults on post-acute stroke patients

The aim of the present study was to develop an automatic controller for FES cycling able to assure a symmetrical pedalling. The controller is therefore exploitable in the rehabilitation of hemiplegic patients. Starting from a measurement in real time of the bending moments produced at right and left crank, the controller tries to reduce the unbalance of the movement and then to maintain a symmetrical pedalling. To reach this goal the controller updates the stimulation pulse width of the two legs independently. Specific FES cycling experiments were carried out on two healthy subjects and two hemiplegic patients to test the controller. These trials showed that the controller was able to reach and then to maintain a symmetrical pedalling. In particular, the controller took less than 1 minute to achieve a stable condition. The symmetry controller developed could accelerate the recovery of motor symmetry, crucial aspect in the rehabilitation of stroke patients.