Page 241 - LEGO MINDSTORMS - Robotics Invention System-2 Projects

Robot 8 • The ULK (Useful LEGO Knowledge)

Base Step 1a

A differential drive won’t travel in a straight
line without some sort of tracking
correction. Some robots use rotation sensors
and special software to ensure that both
wheels travel the same distance. ULK uses a
clutch to coerce the left and right wheels
into turning at the same speed.
A ribbed hose slipped over the drive axles
makes a simple and effective clutch. I cut a
piece three studs in length from the long
teal hose. If you are nervous about defacing
any of your LEGO pieces, Base Step 1b
shows an alternate wheel attachment that
doesn’t require any cutting.

Base Step 1b

If you choose to not use the clutch,
additional support for the drive axles
help ULK drive a little straighter.

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