Breakout Chairman: Dan Siewiorek, Carnegie Mellon University

Several observations set the context for the discussion. The first observation is that wearable computers are different from desktop computers. In particular, the desktop metaphor of windows, icons, menus, and pointers (WIMP) is not the metaphor for wearable computers. There was some discussion about what was a "wearable computer". The consensus was that wearable computers were "always on" in contrast to notebook computers which are "mostly off". Thus watches and cellular telephones could be considered instances of wearable computers. Second, a "killer application" would help launch wearable computer software. The microprocessor and operating system technologies already exist for wearable computers. What is missing is the word processing and spreadsheet type applications which drove the desktop computing revolution. Third, the main application for wearable computers would be acquiring, storing, and retrieving data.

System Architectures

Three different system architectural approaches were identified. Each approach had both advantages and disadvantages. The first approach building upon desktop computer technology. Commercial off-the-shelf (COTS) hardware (e.g., Intel processors, etc.), operating systems (DOS, Windows, etc.), and application software could be used. As noted before, the desktop metaphor is poorly suited to wearable computer applications. By adopting mainstream platforms from the desktop there is extra overhead in processing power, storage, and power consumption for the wearable computer application. However, COTS software is portable, reusable, and minimizes application development time.

The second architectural approach builds upon real-time embedded system technology. Low energy processors, real-time operating systems, and custom software could produce lighter weight, longer battery life, and more responsive applications. However, real-time operating systems have a limited number of software drivers and the system developers may have to write software drivers for input/output devices that are not normally encountered in embedded systems (e.g., global position sensing, speech recognition, etc.). The development time for application software may be longer than for desktop systems since there are a limited number of software development tools for embedded systems. However, this cost can be offset if dedicated application metaphors are developed that have standards for intercommunication and information exchange.

The third approach could be built upon the emerging web browser technology. Future dedicated web browser hardware and operating systems could be augmented by web "plug in" applications allowing the wearable computer user to become a network node.

The discussion in the breakout session then turned to wearable computer subsystems. In particular, head-mounted displays and energy sources were considered.

Head-Mounted Displays

During a brain-storming session over 30 attributes of head-mounted displays were identified. participants were each given a fixed number of votes to select what they felt were the most important attributes. The following are the top ten attributes determined by the vote.

1. Smaller, lighter
2. Focal depth, eye relief, convergence/accommodation
3. Cost
4. Ruggedized, temperature extremes
5. Low power
6. Position in the field of view including moving out of the way and disabling the display
7. More comfortable
8. Color display
9. Wireless connection to the wearable computer
10. Resolution greater than VGA

Note that half of these attributes can be considered human factors (i.e., 1, 2, 6, 7, and 9). It was also observed that industry was working on all the attributes except #6, position in the field of view.

Energy

The discussion focused on batteries. The goal should be one power source with redundancy for added capacity. In particular, a single standard battery type would be very attractive, For example, the land warrior has nine different battery types. In consumer electronics we have seen the size of the standard battery decrease from D to C to AA to AAA. The desire is to have a highly-available battery form factor.

Since battery technology moves slowly, the focus in wearable computers should be on power reduction using lower power components and better power management.

Interconnection Standards

The group felt that an important standardization activity should be the interconnection between wearable computer subsystems such as the head-mounted display, batteries, and computer. Currently, each wearable computer has its own connectors and wire harnesses. In the near future it would be very desirable to have standard connectors and standard buses so that subsystems from various vendors could be intermixed into different systems. In the future it would be highly desirable if all the components could communicate in a wireless fashion.