Cancellation of Feedthrough Dynamics Using a Force-Reflecting Joystick

Abstract

Abstract This paper reports on a set of theoretical and experimental investigations into the use of force reflection to enhance the dynamic behavior of human piloted vehicles, especially joystick-controlled vehicles such as fly-by-wire jets, bulldozers, and powered wheelchairs. Briefly, force reflection is used in the manual controls to cancel the effects of feedthrough dynamics. Feed-through dynamics refers to generation of inadvertent steering or speed command inputs due to the action of inertia forces between the pilot’s hand and manual controls. These inertia forces arise in the pilot’s body in response to vehicle accelerations. To eliminate feedthrough dynamics, a canceling force is produced on the force-reflecting joystick using a model of the pilot dynamics and the known vehicle accelerations. A custom motion platform and a commercial force-reflecting joystick are used in a set of experiments to test the idea. Parameter values for an assumed model are estimated by observing the response of the pilot’s body to known platform accelerations. Cancellation of feedthrough dynamics is demonstrated for a human subject.