Tag Archives: capacitive sensing

Sometimes when we touch: Touché, a sensing project from Disnery Research and Carnegie Mellon

Researchers at Carnegie Mellon University and Disney Research, Pittsburgh (Philadelphia, US) have taken capacitive sensing, used for touchscreens such as smartphones, and added new capabilities. From the May 4, 2012 news item on Nanowerk,

A doorknob that knows whether to lock or unlock based on how it is grasped, a smartphone that silences itself if the user holds a finger to her lips and a chair that adjusts room lighting based on recognizing if a user is reclining or leaning forward are among the many possible applications of Touché, a new sensing technique developed by a team at Disney Research, Pittsburgh, and Carnegie Mellon University.

Touché is a form of capacitive touch sensing, the same principle underlying the types of touchscreens used in most smartphones. But instead of sensing electrical signals at a single frequency, like the typical touchscreen, Touché monitors capacitive signals across a broad range of frequencies.

This Swept Frequency Capacitive Sensing (SFCS) makes it possible to not only detect a “touch event,” but to recognize complex configurations of the hand or body that is doing the touching. An object thus could sense how it is being touched, or might sense the body configuration of the person doing the touching.

Disney Research, Pittsburgh made this video describing the technology and speculating on some of the possible applications (this is a research-oriented video, not your standard Disney fare),

Here’s a bit  more about the technology (from the May 4, 2012 news item),

Both Touché and smartphone touchscreens are based on the phenomenon known as capacitive coupling. In a capacitive touchscreen, the surface is coated with a transparent conductor that carries an electrical signal. That signal is altered when a person’s finger touches it, providing an alternative path for the electrical charge.

By monitoring the change in the signal, the device can determine if a touch occurs. By monitoring a range of signal frequencies, however, Touché can derive much more information. Different body tissues have different capacitive properties, so monitoring a range of frequencies can detect a number of different paths that the electrical charge takes through the body.

Making sense of all of that SFCS information, however, requires analyzing hundreds of data points. As microprocessors have become steadily faster and less expensive, it now is feasible to use SFCS in touch interfaces, the researchers said.

“Devices keep getting smaller and increasingly are embedded throughout the environment, which has made it necessary for us to find ways to control or interact with them, and that is where Touché could really shine,” Harrison [Chris Harrison, a Ph.D. student in Carnegie Mellon’s Human-Computer Interaction Institute] said. Sato [Munehiko Sato, a Disney intern and a Ph.D. student in engineering at the University of Tokyo] said Touché could make computer interfaces as invisible to users as the embedded computers themselves. “This might enable us to one day do away with keyboards, mice and perhaps even conventional touchscreens for many applications,” he said.

We’re seeing more of these automatic responses to a gesture or movement. For example, common spelling errors are corrected as you key in (type) text in wordprocessing packages and in search engines. In fact, there are times when an applications insists on its own correction and I have to insist (and I don’t always manage to override the system) if I have something which is nonstandard. As I watch these videos and read about these new technical possibilities, I keep asking myself, Where is the override?