|
QUESTION:I've a vehicle that works well in the lab, using
two small geared motors, with r/c monster truck
wheels, and a castor at the front. Power comes
down an umbilical cable from a power supply.
I want to let it loose in the big wide world, which
means carrying its own power supply. I would
like to use a car battery or similar- but that would
mean its got to be big, so I'm into mechanical
problems.
As it works with two wheels + a castor, the
easiest step would be skid-steer. Two rows of
wheels with tracks on means I only have to
get drive to one wheel per track, but how do I
obtain or make substantial track?
I have considered 4 or 6 wheels and no track
(pathfinder Sojourner style), but would have
to get drive to all wheels for skid steer to work.
ANSWER: Interesting you should ask. I've been musing about the possibility of
building a bot that would be agile on various terrains. What came to my
mind was a belt (similar idea to what others have mentioned) like the
one on my race car. If you aren't familiar with those, they come in
several different flavors, but are all toothed in design. Mine is called
a Gilmer style, and it's three inches wide with teeth that have half
inch pitch. It's used to run the GMC 6-71 blower sitting atop the
engine, by the way. I surmised I'd flip one over and put the teeth on
the outside, which of course would necessitate having the drive sprocket
somewhere on top and on the outside of the "track". I haven't priced a
new one lately but a few years ago I could pick them up for about fifty
bucks. These belts are pretty common around the U.S. since all the
racers/truck pullers have gone to the "millimeter" drives. Two inch
widths are fairly common also. Obviously, used ones are a much better
deal, and unless they've been shredded, would be fine for a bot track.
If someone out there employs a large Gilmer belt for a track before I
get the chance, let us all know how it works out.
This isn't terribly difficult or expensive. Consider the motors used in
kid's sidewalk cars. They can be had cheap from surplus houses, and I've
found two of these cars (2 motors each) set out for the trash collector in
the last 6 months. You really only need to power four of the wheels on
a 6-wheeled bot. Note, though, that Sojourner isn't skid steer, it turns
the wheels.
I put together a page with a picture of using molded ladder-chains
and sprockets for a tracked robot. These come in a variety of sizes
and work quite well in areas without flat floors.
|
|
|
|
