Tickle (prototype #1 1996) is a small autonomous robot: a blank aluminium capsule that is fitted with a pair of nubbed rubber caterpillar tracks, to give a pleasurable tickling skin massage.

Tickle crawls over a reclining body, powered by rechargeable batteries and equipped with sensors and motors. It has one motor for each track, so it can move forward or backward and it can turn left or right. A sensor measures pitch and roll angles and the control program decides how to move. The robots orientation is connected to its motion in a way that prevents it from falling off the subjects body. When it encounters a slope that is too steep, it will pivot until a safe level is found and continue its wandering, unpredictable path.