Wouldn’t it be cool if you could make your desk interactive? Pressing on the right side to skip the song you’re playing, on the left to start it again, and on the middle to pause it? Using Echotube you can! Echotube is an approach to add touch and press sensing to existing objects using ultrasound. Echotube is made up of four very easily accessible components: a rubber tube, an off-the-shelf ultrasonic transducer, our custom built software (this you can get from Github), and a microcontroller to drive the transducer, and relay the data to our software. To assemble these components is as easy as connecting the transducer and the rubber tube, and also the transducer to the microcontroller. Last, you connect the microcontroller to the computer running our software and you’re ready to go!
Echotube has a series of benefits when compared to the other techniques researchers have investigated. Echotube is very robust, since all of the sensible electronics are hidden away from where the interaction is taking place. Echotube is flexible, it is possible to route the rubber tubes around objects of different shapes. Last, Echotube is inexpensive, all the components can be bought for less than $30.
How does it work?
We’ve all experienced echoes, hearing yourself talk (or yell) with some delay after the space you’re in bounces the sound of your voice back to you. This is the main concept behind transducers: they constantly emit a sound (usually in very high frequencies so humans can’t hear it), and wait for the reflection, or echo, to reach back to it. Since it is know how quick sound travels through air, depending how long the sound takes to come back, the transducer can estimate how far the object is. Echotube is based on this very principle, but we instead enclose the sound, and its echo, in a tube (get the name now?), allowing us to detect presses along this tube.
Echotube is robust
Because all the sensitive electronics are placed away from where the interaction is taking place, this means that Echotube can be deployed in very adverse conditions. Examples of this is (as seen on the picture above) using Echotube as a bicycle counter, and (as see on the picture below) using Echotube to control music playback while fully submerged on a sink.
Echotube can be deployed where normal touch sensors can’t: here is an example of using Echotube in a sink full of water to control music playback.
Echotube is modular
A very interesting thing about Echotube is that thanks to it’s almost 3 meters of range, this range can be made up of smaller tube sections. Below we see an example where we connect three Echotube buttons by extending the original tube.
You can download this paper from the ACM Digital Library, or directly from this website.