Quote:
Originally posted by Gope
Ummm...if u control everywheel independantly you run the risk of running them in opposite direction due to either driver or programing error and either stalling ur motors or ripping ur bot appary....sounds way to risky for the very very little advantage it gives over crab steering
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There are many different ways of successfully incorporating crab steering into a design. The two many ways are either 5 or 8 motor designs.
Each unit/wheel is mounted on a vertical shaft, and consists of a wheel driven by a motor. The motors need to be geared so that they all spin at approximately the same RPM. Then, for the 8 motor design, each vertical shaft is driven by a motor so that the shafts can be rotated independently. This design requires a potentiometer on each shaft to recieve the direction of the wheels. Because of this, the wheels cannot be rotated a full 360 degrees, or the potentiometer will be damaged.
The 5 motor design uses the same wheel unit, but uses sprockets on the vertical shafts. Then, all the shafts are connected by a chain, which is driven by 1 single motor. I remember one bot that used this. They used 2 Fisher Prices, 2 drills on their wheel units, and then used the extra drill for rotating the wheels. The cons of this design, is if the chain "skips", one wheel will be thrown off. I'm not sure if it's necessarily lighter because of the chain (I would probabaly use 3/8" to be safe, but I think they used 1/4"). The advantage is that it is simpler, and you would only need 1 potentiometer to tell the direction of the wheels, and less motors and gears need to be used.
WildStang CAD Drawing Picture 2nd Picture WildStang Website
Check the whitepapers section.