Positraction Shoes

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 When the shoe detects 'smooth-hard-slippery' surfaces underfoot the outer ring of each lug is extended and the others withdrawn.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.