As I mentioned in the last blog post, we were inspired by the Feelspace Project (which gives you a magnetic compass sense, like migrating birds) to have a go at making a wearable device that would allow you to feel your surroundings – essentially extending your sense of touch out to a range of three metres or so.
The idea is to have a set of rangefinders in armbands that point outwards around your body. Each armband also has vibrators in that vibrate against your skin at an increasing frequency as the range from each sensor gets smaller. The left armband covers your left-side surroundings, and the right your right-side.
Our researcher Matt and I programmed an Arduino Uno to loop through a bunch of the rangefinders in turn getting a distance in metres from each and to use the results to set the mark/space ratio of the signals sent to the corresponding vibrators. The Uno outputs can drive the vibrators directly with no extra electronics needed, as they are very low-current.
The whole thing is powered by one of those recharge-your-phone USB battery packs. These are compact, and have enough amp-hours of charge to run the device for over sixteen hours a day (that is to say, all the time you are awake, with overnight recharging). For the Arduino, they also conveniently provide power as a USB socket.
We made the armbands by directly printing on the fabric that will form them as described in the last post. This allowed us to construct a case for each ultrasonic sensor and a holder for the corresponding vibrator in a hole in its base. The only mechanical location of the vibrator was done by the fabric, which allowed it to be pressed against the skin by simply putting a little foam rubber in the case to push it downwards bending the fabric slightly. It could then vibrate freely.
It works! It needs some extra adjustments and a bit of tidying up and refining, but you can feel walls, and even bushes, as you get close to them, and you know whereabouts relative to you they are.
Here is Sally using the device. Note that all the time she is moving in the video she has her eyes closed.
Feelspace have found that, when you wear a device like this, your brain integrates the signals into your sensory map and moves the processing down into your subconscious. Thus, with their compass sensor, after a few weeks the wearer finds that they have a near perfect sense of direction and – equally interestingly – when asked how they do it they can’t put the experience into words, just as we all cannot explain by introspection how we see what we see.
All the files for this project are on our Github repository with an OS licence so feel free to download them and have a go yourself.
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