Automatic synchronization of functional electrical stimulation and robotic assisted treadmill training.

This work presents a means to automatically synchronize two promising gait training technologies to address gait deficits in stroke survivors: functional electrical stimulation using intramuscular electrodes (FES-IM) and the Lokomat robotic gait orthosis. A system of hardware and software was developed to achieve the automatic synchronization. A series of bench tests were performed to verify the feasibility and reliability of automatic synchronization. The bench tests showed that automatic synchronization of FES-IM to the Lokomat gait cycle was feasible and reliable. Automatic synchronization was more consistent than manually triggered stimulation (10-fold smaller standard deviation of latency), and produced no early or missed stimulations across 634 strides. Automatic synchronization had greater accuracy than manually triggered stimulation, producing stimulation timed to an accuracy of 2.5% of one gait cycle duration (heel strike to heel strike = 100).