Subject:
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Pneumatic "One Leg at a Time" Robot Circuit
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Newsgroups:
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lugnet.technic
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Date:
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Tue, 13 Sep 2005 16:46:11 GMT
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Viewed:
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3620 times
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A while ago I saw an electric robot on TV that had 6 legs in 2 rows of 3 and
moved one leg at a time forwards (lift, forward, down), then all back together.
I thought this is an ideal application for Lego pneumatics.
I don't still have it built, but my prototype leg used parallelograms to lift
the foot vertically, keeping its track constant but allowing it to swing forward
and back. The hip joint was based on a technic turntable. I used one cylinder
for the foot and two for the hip, working in opposite directions on bevel geared
axles to turn the turntable.
Here's the pneumatic circuit diagram that will allow the above function to be
realised, whilst allowing a variable number of legs to be used. The diagram has
2 leg modules in it, but the table shows enough columns for four legs. I
suggest that four legs is probably the minimum for stability but I'd be
interested to see a stable tripod.
http://www.brickshelf.com/gallery/mbellis/Technic/Pneumatics/Building-Blocks/pneumatic_one_leg_at_a_time_robot_circuit.jpg
There are 5n+3 steps in the cycle, where n is the number of legs. The circuit
uses 3n+1 (or 4n+1) cylinders and 7n+2 valve switches.
Load bearing is accommodated by the fact that all the legs share the weight, so
if a small pressure drop occurs when a raised foot is lowered, all the other
feet would rise a bit rather than one leg rising all the way, and it would equal
out by the time the raised foot was fully lowered.
As well as walking robots, this circuit lends itself to any function that
requires several sub-systems to operate in sequence, with a global reset at the
end.
Mark
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Message has 1 Reply:
 | | Re: Pneumatic "One Leg at a Time" Robot Circuit
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| (...) Hi Mark, Now I know what to build next..... a four legged walker that lifts one leg at a time. On paper it looks like I can get one made for 1+2n pistons and 2+4n switches. This assumes that legs mechanically lock when weight bearing. I don't (...) (19 years ago, 13-Sep-05, to lugnet.technic)
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