A Virtual Retinal Display For Augmenting Ambient Visual Environments

by Michael Tidwell

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Chapter 5: Applications of an Augmented Vision Display

5.1 Introduction

This chapter explores the potential usefulness of an augmented vision (see-through) display system using application examples in medicine and manufacturing. These examples provide insight into the functionality of the system, although other applications are certainly possible.

5.2 An Application in Medicine

The proposed medical application is an augmented vision display for fluoroscopic examinations. A fluoroscope is a "real-time" x-ray device. A patient lies on a movable table between a low level x-ray source and a signal amplifier (x-ray detector and photomultiplier system). The signal amplifier sends video information to a monitor. While the x-ray source is on, the radiologist sees a real-time x-ray of the patient. Once the patient is in a desired position (determined by looking at the monitor), a hardcopy X-ray (onto film) is taken. To get the patient in the desired position, however, the table has to be translated and rotated and the patient sometimes has to be physically moved on the table.

The video monitor acts as a sort of information transducer in the feedback loop. The monitor converts the information "Where is the patient's organ?" to a visual form. The problem is that the video monitor can also slow down the feedback for two reasons; a) the radiologists must look away from the patient to look at the monitor and, b) the monitor is heavy, bulky, and difficult to move around. A light weight augmented vision display may solve both problems.

With an augmented display, the radiologist gets immediate visual feedback because the x-ray video follows the radiologist in his or her field of vision. The field of vision could constantly contain the video image and a switch could change the display intensity in a fraction of a second. It is also possible to use the exit pupil of the optical system as a switch. If the optical system is design and aligned properly, the user could view the display by looking in one direction, say slightly upward, and not view the display (but see the outside world) by simply looking in any other direction, say straight ahead, left, right, or down. In the latter approach only a slight gimbal of the eyes upward brings information to the radiologist for which he or she otherwise would have to look away from the patient.

In this particular application, weight is critical. The radiologist performs numerous examinations per day. If the display is too heavy (much more than a pound), fatigue becomes an issue in the performance and comfort of the radiologist. More work is needed to determine the exact design weight parameters for the medical field.

5.3 An Application in Manufacturing

In a manufacturing setting, an augmented vision display affords the user freedom from certain physical limitations. The worker no longer must be at a certain place to receive information. For example, a worker must no longer be at a drawing table or a computer terminal to see a large scale drawing. Instead, a worker could be off-site or across a factory floor and still receive a visual copy of the drawing. A see-through display informs the worker in conjunction with the physical environment without restriction on the worker's location. The result is higher quality information transfer, higher productivity, and fewer manufacturing errors.

For example, the Boeing Company is attempting to incorporate augmented reality into the aircraft manufacturing process [33]. The manufacture of aircraft is still a high manual labor process and it is important to maximize the efficiency of each worker. One possible way to reduce errors and maximize work time is to superimpose information such as blueprints, computer aided design (CAD) drawings, and part location directly over the work area.

A specific application in aircraft manufacturing is in the wiring process. Currently at Boeing, large formboards are setup on which wiring harnesses are assembled. With pre-process calibration and accurate head tracking, an augmented reality display system could superimpose proper wire locations, wire types, and alphanumeric information over the formboard. Essentially the system would trace out wires in front of the assembler in their proper location on the formboard. Because head position is calibrated and tracked, a computer knows at all times where the assembler's view is directed in reference to the formboard. Consequently, the wire assembler can just follow a single computer generated wire that leads along the correct path. The assembler no longer needs to discriminate between wires on the formboard or the blueprint.

Human Interface Technology Laboratory