ping stick

feb 2020 note: The docs below are for the first model; I made a second, half the diameter, ten times battery life, much improved software (edge emphasis, etc) but haven't documented it. ask me if you care. There are a few pictures of it below.

the ping stick demonstrates some ideas implicit in embodied cognition, the philosophical idea that, in essence, what we call 'mind' is deeply and irretrievably embedded in, a part of, the body. it's a really interesting subject and a useful way to think about thinking and the body and interface (computer or otherwise) . the wikipedia page on embodied cognition is a decent introduction.

the ping stick couples your sense of touch to your mind's "visual" comprehension of space. put simply, you can feel the physical environment around you with your fingertip, and walk around a room or other space with your eyes closed. with essentially zero training, just holding the thing in one hand and gently waving it in front of you as you walk, you feel/sense/see walls, doorways, furniture, etc around you in a way that immediately makes sense. practice brings much subtlety to its use.

the ping torch is directly inspired by Adam Spiers' haptic torch (University of Reading, UK, 2004), encountered in Professor Simon Penny's reader for his Embodied Cognition class, University of California, Irvine, 2009. mine appears to be simpler, and much smaller (the inexorable stampede of technology).

usage is very simple; you hold it in one hand and point it like a flashlight in the direction you are walking, more or less gently swinging it back and forth in front of you, your finger resting on a small round button on the bottom. the sole purpose of the ping stick is to vibrate the small touch-button with an intensity proportional to distance to an object such as a wall or a chair, with things closer vibrating more intensely.

the vibrating button is the sole output; no pixels, LEDs or sounds. there is a power switch (which i would like to eliminate) and a sonar sensor in front, and no adjustments of any kind. software within the device translates sonar range (distance) data from the sonar device, into vibration intensity in the tiny motor. technical details are below.

the result is a fairly immediate mapping of what would seem to be utterly unrelated cognitive events; arbitrary sensation in a fingertip, and visualization of space. this is apparently due to the spectacular redundancy and innate ability of the body/mind to analogize sensory data, analogous (to me) as a form of useful synaesthesia. (it is very much like the instantaneous bodily orientation one gets by suddenly touching a wall after wandering around in a pitch-dark room; one swipe of a hand across the wall tells you much about the space that persists for some time after you walk away from the wall).

here's a brief (8 second) movie of it swept past a wall edge. this awkward video was taken with a remote microphone held onto the vibrating button so that it can be heard in the video as a mild buzzing. Note the edge-emphasis as it sweeps past the stepladder leaning on the building.

technical details

the ping torch consists of a Sparkfun Arduino Mini Pro, an EZ-1 sonar sensor (see note below), a vibrating motor, power supply and support glue, and housed in a thin wall aluminum tube. the software is almost trivially simple: sonar range is taken continuously (as the power button is held down), at the EZ1's maximum rate of about 20 measurements/second, and that range (in inches) is translated to an arbitrary "intensity" value. some heuristics are applied: the mapping is logarithmic, not linear; things closer are more "interesting" (collision avoidance, etc). objects beyond 80 inches are intentionally ignored; "feeling" things beyond that became confusing (sounds quite arbitrary here in type, but experienced quite obvious). to somewhat help overcome response time limitations inherent in the sensor, edge emphasis is done when there is an abrupt change in distance, eg. sweeping the sensor past a doorway, or an object projecting from the wall. emphasis is done by differentiating the range and adding this into the steadystate intensity. edges feel more edgy.

Second version, innards

First version, described above

Website contents, unless otherwise specified, © 2023 by Tom Jennings is licensed under CC BY-SA 4.0