Even while walking rather slowly, making a turn indoors requires significant acceleration since the radius is generally rather small. The problem is that the acceleration is perpendicular to the current velocity, so the ankles get strained sideways.
By attaching small, firm wedges to the floor, you could create a 'selectively banked' turn. That is, you could choose to step on the wedges in sequence and experience a banked turn, or you could choose to step between the wedges for an un-banked turn.
Alternatively, the wedges could be continuous and radially varied in slope (greater toward the walls). This system would have the advantage that users could account for temporary changes in coefficient of static friction and incoming velocity by choosing the appropriate radius of travel.
For a person weighing 70 kg turning with radius 1 meter at speed 1.33 meters per second (3 mph), the wedge angle would have to be 10.4 degrees to eliminate the need for lateral friction. If the width of a person's shoe could fit on a wedge 15cm (6in) wide, then the 'selective banking' wedge is less than 3cm tall. Yeah, you'll probably trip on it, and you may have trouble with wheeled equipment, which is one of many reasons why this works best in stairwells.-- Ketchupybread, Mar 10 2009 Active Sole! for people with somewhat inactive Active Soul!
overall i expect that this idea will appeal to people who are lazy walking turners, i read this and then saw one. Funny how the slightest suggestion makes you notice things.-- vfrackis, Mar 10 2009 I must be dizzy but I've no idea what in hell either of you are discussing.-- blissmiss, Mar 10 2009 The same effect could be achieved 'client-side' with shoes that actively alter the sole-to-heel angle with hydraulics. For this option, you would have to tell your shoes before making a turn.-- Ketchupybread, Mar 10 2009 On Monday I spoke with my shoes and I made it perfectly clear to them that I would be turning left and that I would be turning right.-- vfrackis, Mar 10 2009 Didn't Maxwell Smart talk into his shoe?-- blissmiss, Mar 10 2009 This is all fine & good but what if you are carrying a bowl of soup or a tray of drinks? The strain on your ankles would be reduced but you would have extra strain on your wrists & arms. As the ankles seem to be the weak link here, I think it would probably be better to get rid of them altogether. I propose a trip to the garden shed followed by a quick bit of sawing to see them off. Then simply replace your lower leg with casters. Problem solved.-- DrBob, Mar 10 2009 Like the idea [+], but what happens if your orthopedic inserts cancel out the banking?-- eight_nine_tortoise, Mar 11 2009 Interestingly, London Transport implement a form of this, by making pedestrian tunnels in underground Tube stations roughly circular in cross-section. If they were perfectly cicular it would be great - in fact they have a flat segment at the bottom, but even so, it is sometimes possible to use the sloping wall to conserve momentum when walking fast around corners in tunnels (oblig.: "You are in a maze of twisty tunnels, all alike" comment). Anyway, [+]-- hippo, Mar 11 2009 random, halfbakery