Iterative learning control as an enabler for goal oriented upper limb stroke rehabilitation

People re-learning skills after a stroke go through the same process as someone learning to play tennis, but they have a problem because they can hardly move at all so they cannot practise, which means they dont get feedback. Muscles can be made to work by electrical stimulation where electrical impulses travel along the nerves in much the same way as the electrical impulses from the brain. If stimulation is carefully controlled, a useful movement can be made. This works better if the person is attempting the movement themselves; we therefore need to combine a persons own effort with just enough extra electrical stimulation to achieve the movement. Previous research with supporting clinical trial data has shown that iterative learning control can be used to regulate the electrical stimulation applied with the essential requirement that if the patient is improving with each attempt the level of voluntary effort increase and the applied stimulation decreases. This paper reports results, including patient experimental data, where wrist and hand extensors are also stimulated using a 40 element surface electrode array and thereby moves closer to facilitating the re-learning of goal oriented tasks that are essential to move this technology towards home use.