title: Application of the Actor-Critic Architecture to Functional Electrical Stimulation Control of a Human Arm.
abstract: Clinical tests have shown that the dynamics of a human arm, controlled using Functional Electrical Stimulation (FES), can vary significantly between and during trials. In this paper, we study the application of the actor-critic architecture, with neural networks for the both the actor and the critic, as a controller that can adapt to these changing dynamics of a human arm. Development and tests were done in simulation using a planar arm model and Hill-based muscle dynamics. We begin by training it using a Proportional Derivative (PD) controller as a supervisor. We then make clinically relevant changes to the dynamics of the arm and test the actor-critic's ability to adapt without supervision in a reasonable number of episodes. Finally, we devise methods for achieving both rapid learning and long-term stability.
authors.affiliation: Department of Electrical Engineering and Computer Science, Case Western Reserve University.
authors.forename: Philip
authors.initials: P
authors.lastname: Thomas
authors.forename: Michael
authors.initials: M
authors.lastname: Branicky
authors.forename: Antonie
authors.initials: A
authors.lastname: van den Bogert
authors.forename: Kathleen
authors.initials: K
authors.lastname: Jagodnik