Donald M. Spaeth, PhD, RET, Rory A. Cooper, PhD, Jeremy Puhlman, BS

ABSTRACT:

There is long standing debate among researchers in the control interface community regarding relative merits of isotonic (movement sensing) vs. isometric (force sensing) joysticks. There is evidence that consumers may be better served if their control device can be customized to match their specific needs. For our current research, we are developing a variable compliance joystick which can be adjusted across the isotonic/isometric spectrum. It is based upon an isometric beam sensor with a flexible extension made of polyurethane rod. The elastimer is constrained to two degrees of freedom by an open center gimbal. The compliance is adjusted by either changing the durometer of the elastimer or restricting the length of the elastimer segment permitted to bend. A successful first generation prototype has been tested.

KEYWORDS: Isometric controls, Isotonic controls, Buckling spring, Joysticks, Power wheelchairs

Donald M. Spaeth, PhD, RET
Human Engineering Research Laboratories (151R1)
VA Pittsburgh Healthcare System
7180 Highland Drive
Pittsburgh, PA 15206
(412) 365-4850