Towards automatic optimization of gait supported by a two channel implantable drop foot stimulator

An automated system is developed to optimize the timing and magnitudes of stimulation for a twochannel drop foot stimulator on the basis of criteria for the quality of the movement of the foot during the swing phase of gait. These criteria encompass the timing of the start of dorsiflexion movement after heeloff, foot clearance during the swing phase, and balance between inversion and eversion and heel-first foot placement at the end of the swing phase. These criteria are evaluated using a six degrees of freedom inertial sensor system placed on the foot. On the basis of this evaluation, the timing and magnitude of the stimulation are adapted from cycle-to-cycle. The observability of the formulated movement criteria from the inertial sensor measurements have been preliminary evaluated in a patient experiment with and without stimulation of the peroneal nerve. The approach is intended to result in an evaluation and tuning system for clinical use.