Optimization of a fes cycling neuroprosthesis on stroke patients by means of the left and right crank measurements

The use of functional electrical stimulation (FES) is a well established method in the rehabilitation of stroke patients. In particular, a bilateral movement such as cycling induced by FES would be crucial for these patients who had an unilateral motor impairment and had to recover an equivalent use of the limbs. To improve the rehabilitative effects of the FES cycling, a metrologically qualified cycle-ergometer was used, so that the left and right crank torque values are measured in real-time. Three protocols were evaluated. First, healthy subjects performed voluntary pedaling. Second, healthy subjects were stimulated one muscle individually to study the contribution of each single muscle to the cycling. Third, stroke patients executed a complete FES cycling trials. Results demonstrated that the proposed sensors could be successfully used to monitor online the unbalance of the cycling. Single muscle tests showed that only the quadriceps and the hamstrings provided a significant contribution to the crank torque. Patient trials confirmed the difficulty for stroke subjects to carry out symmetrical cycling. The use of the proposed sensors, hence, could offer a good signal for biofeedback neuroprostheses and for closed loop controllers.