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Wearable Computer Systems for Affective Computing

The unique needs of an affective computing system present challenges to designers of hardware as well as software. We expect to build systems that maintain not only constant sensing contact with the user, but also contact via more traditional user interface paradigms. One solution to these hardware design challenges that we are investigating is the wearable computer. Several research projects in Affective Wearable systems are currently underway, and may be seen at the bottom of this page.

Wearable computers are entire systems that are carried by the user, from the CPU and hard drive, to the power supply and all input/output devices. Such systems are under development here at the Media Lab, where we are also working to create prototypes of uniquely affective wearable systems. The size and weight of these wearable hardware systems are dropping, even as durability of such systems are increasing. We are also designing clothing and accessories (such as watches, jewelry, etc.) into which these devices may be embedded to make them not only unobtrusive and comfortable to the user, but also invisible to others.

Wearable computers allow us to create systems that go where the user goes, whether at the office, at home, or in line at the bank. More importantly, they provide a platform that can maintain constant contact with the user in the variety of ways that the system may require; they provide computing power for the all affective computing needs, from affect sensing to the applications that can interpret, understand and use the data; and they can store the applications and user input data in on-board memory. Finally, such systems can link to personal computers and to the Internet, providing the same versatility of communications and applications as most desktop computers.


For more information on affective wearable computers, see the Vision and Modeling Group's Technical Report (TR) page, specifically:

The prototype affective computing system we are currently developing uses a modified "Lizzy" wearable. We have several such wearable systems, and plan to use them to create a uniform set of affective computing hardware platforms, both to conduct affect sensing/recognizing experiments, and to develop eventual end user systems. An example of this hardware system is shown below. The computer module itself is five and a half inches square (about the length of a pen), by three inches deep. It runs the Linux operating system. The steel casing can protect the computer in falls from heights up to six feet, even on hard surfaces like concrete. This system is durable enough that it can withstand occasional blows, knocks, even the user's accidentally sitting on various parts of the system without damage.

The wearable computer module we are using to develop the affective computing system. The strong steel case is five and a half inches square by 3 inches deep, shown with the cover on (left) and off (right).


Output devices

Three interface devices for wearables: The Private Eye (left) provides a tiny monitor display that only one eye can see, and may be mounted on a pair of safety glasses. The JABRA net (right) is an earphone device for listening to auditory output from the system. The green part of the JABRA fits in the ear; a microphone that sits on the end that is exposed to the outside is for listening to sound that the ear would normally hear without the earpiece. The PalmPilot (middle) is a PDA that can be used without obscuring the user's vision.

The Private Eye
Instead of an LCD screen monitor attached to the computer (as with a laptop model), the wearable computer uses more robust, personal interfaces for "hands free" operation which allows the user to walk around freely and have the computer operational at all times. Currently, the standard interface for our system is the "Private Eye" (see photo below), a text only interface that is positioned in front of one of the user's eyes. This interface uses a row of LED's (light emitting diodes) and a rapidly spinning mirror to create the illusion of a full screen of text. The Private Eye is a very low power device (one half watt compared to 3.5 watts for typical VGA, head mounted devices) which means a much lighter (and therefore slower) drain on the battery.

The Palm Pilot is an example of a more socially acceptable interface. While it is uncommon to see someone wearing a head mounted display or earpiece, it is fairly common to see someone using a Palm Pilot. This interfaces allows the user to harness the full power of the wearable while remaining socially inconspicuous.

The JABRA net (as shown, below) is an example of a lightweight, auditory interface, and a candidate output device for the affective wearable computer. This interface paradigm leaves the user's eyes unobscured, and is barely noticeable to the casual observer. An auditory interface like the JABRA would serve well for a variety of applications, including those that are not vision intensive. Using this interface, the computer would use computer generated speech to speak with the wearer; the user would be able to communicate with the system via several possible means:

  • A one handed keyboard like the Twiddler (see below);
  • A PDA style handwriting tablet or miniature keyboard;
  • Eventually by speaking directly to the system, with a speech recognition system in tandem with a microphone.

Input devices

The Twiddler is currently the preferred input device for wearable computers. It is a lightweight, one-handed, "chordic" keyboard. A chordic keyboard, like those used by court stenographers, produces characters by pressing combinations of buttons. Two handed chordic keyboards are capable of typing speeds that are much faster than traditional QWERTY keyboards; an experienced user of the Twiddler can exceed speeds of 50 wpm while using only one hand. The Twiddler is made by HandyKey, and is friendly to user modifications such as remapping the keys or reconstructing the case. The Twiddler shown here has an attached "orthotic spacer" (the orange lump on the bottom side of the Twiddler in the photo below) which makes operation more comfortable for some users. A chordic keyboard is very quiet, and offers the user a way to silently (and, in many cases, privately) communicate with their computer, a desirable option even after sophisticated speech recognition systems come of age.

The PalmPilot works as an input device as well as an output device. It can be used for both functions simultaneously, or it can be used in conjunction with another device.

Traditional hardware alternatives

Before we obtained a wearable computer we simply used the sensing system in conjunction with a lightweight laptop computer (shown to the right) the Compaq Aero 486. This may still be the best interface for some researchers until the wearable system is fully developed. 

Research projects in Affective Wearable Computing


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