No single shoe sole gives perfect traction on all surfaces. Generally my lug-soled boots slip on wet tile and my sneakers slip in mud. Positraction shoe soles have tiny (1 mm) hard rubber balls set in teflon sockets spaced out on special lugs--a few under the ball of the foot and a few in the heel. When the shoe slips on a wet floor the balls rotate, and sensors in the socket detect slippage (a small amount of movement is ignored). Now, the traction lugs on the soles of these shoes are concentric (two rings surrounding a hard cylindrical center); for 'baseline conditions'the middle ring is in use. When the shoe detects 'smooth-hard-slippery' surfaces underfoot the outer ring of each lug is extended and the others withdrawn. The outer ring is soft, cushy rubber perfect for walking on wet floors. It even has a little bit of a suction-cup effect, though it's not too pronounced. To detect other conditions, simple flap-like sensors are positioned between the lugs, normally out of contact with the ground. When the shoe sinks in gooey stuff the flaps dig in, and if the foot slips the flaps twist, sensors detect slippage, and the hard center portions of the concentric lugs are extended (very much like the cleats on football shoes).

I note that there are patents for retractable-cleat golf shoes and athletic shoes with detachable cleats, but I couldn't find any shoes that sense conditions underfoot and change lugs on the fly.
-- Dog Ed, Jun 15 2001

If you can fit all that mechanical stuff into the 1/4" sole of a wingtip, I'll buy a pair.
-- snarfyguy, Jun 15 2001


Before I read the description I was imagining shoes with a rubber seal around the outside edge and an air pump to maintain a vacuum between the shoe and the ground. This would hold the foot to the ground and improve traction ... perhaps this feature could be incorporated in a future more-expensive line of Positraction Shoes.
-- wiml, Jun 18 2001


Actually, now that the new has worn off the idea, I think that both types of slip sensor--flaps and balls--would clog up in the mud, and even on city streets the balls would pick up grit and quickly cease to turn in their sockets. Back to the thinking board.
-- Dog Ed, Jun 18 2001


something similar to those "Pin-Pressions" executive desk tops might be a good idea - with preasurised gel behind them to push them out, they would mould to the shape of the ground exactly.
-- CasaLoco, Jun 20 2001


CasaLoco, that begins to sound like the "SmartWheels(tm)" from Snow Crash. That being a somewhat over-the-top sf novel, the smartwheels used miillimeter-wave radar and lots of computation to adjust the zillions of individually rubber-tipped spokes. But a more passive device might work as well.
-- wiml, Jun 21 2001



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