(Dr. Wayne Book, advisor)

"Implementation of an Active Haptic Display as a Research Tool for Human Psychophysics Testing"

Abstract

With the increasing sophistication of computer generated environments, attention has been focused on new ways of more fully immersing human users into these computer worlds.  Beyond the traditional interfaces of video monitors, keyboards, mice, and speakers, a number of devices have been designed to allow humans to interact physically with objects that are part of the computer generated worlds.  These devices are known as haptic displays or haptic interfaces.  In order to better understand the effectiveness of haptic displays and to improve their designs in the future, it is important to evaluate humans’ perceptive abilities when using haptic interfaces.  This is particularly relevant for the haptics group of the IMD Laboratory at Georgia Tech, where researchers are studying two very different haptic display configurations: passive devices (not capable of adding or storing energy) and active devices (capable of adding energy to the system).  Until now, however, the lab did not have an active display testbed.

The primary goal of the research was to develop an active haptic display for use as an experimental testbed.  This actively actuated device allows for a variety of useful experiments including, but not limited to: testing new control techniques, evaluating haptic rendering methods, emulating a passive device, and testing human perception and task performance when exploring a virtual environment.  A 2 d.o.f. robot arm with force-sensing capabilities, actuated with dc servomotors, and controlled through a real-time kernel on a Windows NT machine was implemented as the active haptic display.  Various virtual constraints were developed, along with the corresponding collision detection algorithms.  In addition, the control code was adjusted to emulate a passive device.  The testbed was then used to evaluate human perception of stiffness in a virtual environment.  The development of the haptic display, as well as the performance of the human subjects, is discussed in the thesis.