Yes. Marc Raibert's 1, 2, and 4-legged robots from the late 1980s and
early 90s were all based on the basic deisgn of a 1-legged balancing
bot. Used 2-D gymbals for x-y, plus an explosive pneumatic thruster for
z. Check out the following for lots of the theory ....
- dan michaels
A pole in a coffee can filled with cement balances pretty well.
Seriously, *something* has to move or rotate in order to achieve dynamic
balance. Why don't you provide a little more of the design concept so
that the answers aren't so hit or miss. A "1 legged pole" sounds like
you wanted a hopping leg. A pole is a pole, and a leg is a leg.
A stationary Segway or a two-wheeled balancing robot does exactly what
you want, if you think about it. It's a "pole," and though it happens to
be on two wheels, when it's not being driven, it "stands there and stays
balanced." However, looke closely and the wheels are moving ever so
slowly back and forth to provide the balance.
There is no question that trying to convey ideas about physical objects
can be quite a challenge. The search engines don't help much if you
don't know the exact words to search for. But, in this case, there may
not be any good search terms.
Perhaps a new way to word what he is looking for would be "pole sitter"
robot. I think there is a circus trick with that title. However in
that case the are on a flexable pole which is rigidly connected to the
ground at its base.
I have seen people balance on a pole not connected to the ground. In 2
dimensions, I've done it myself when I was on crutches for a short
period of time. Obviously using a gyroscope to exert force is one
method, but I don't think it is necessary because people can balance
themselves on a pole without one. I have a hard time picturing what
kind of physics were involved.
I was thinks in terms of say a 16 inch vertical rod. Attached to the top
are 2 servos that can extend weights in 4 directions. Appropriate sensors
and a control algorithm sense that the robot is falling, and extend the
weight to counterbalance appropriately to maintain balance. Obviously,
slamming the side of the robot would make it fall, but I think it could be
made to maintain balance that way. Or perhaps not?? It would be like a
bipedal robot standing on one leg.
Balance needs to come from below, not above. Haven't seen too many
tightrope walkers use a balancing pole *over* their head.
In Japan they used to have contests on balancing pole robots. They did
use wheels as the concept was similar to a juggler who balances a long
stick on his fingertips. By moving the robot laterally the pole was kept
When you think about it they use their entire body (some don't even use
a pole). In any case, the pole is usually at about the center of mass on
a human, which differs somewhat by sex and body shape, but is roughly
the mid-to-lower abdomen. If a Polebot where to use a similar technique,
it would probably have its balancers at least at its center of mass.
I'm pretty sure you can balance from above with the right configuration.
It works because there would be lateral resistance between the pole and the
floor. The system would push against that to move its center of gravity
opposite the direction of fall.
A weight that moves in the lateral directions at the top of the pole
wouldn't work because the pole would just move and the center of gravity
wouldn't. But if you had a pole in two sections with a pivot in the
center, and a weight at the top, I think that might work. But it might
take three sections.
Inversely, if you had a rigid pendulum hanging from the top of the pole
with weight at the end it might work.
I don't think walking on a tight rope would be possible if you couldn't
balance from above (though some of that works because you can push the rope
left and right with your actions if there is enough slack in the rope).
You could do it for sure if you used air resistance to push against (like
when a tight rope walker cheats by using an umbrella). But I think it's
physically possible by just pushing against the floor in the later
directions if you have the right configuration system.
I've never heard of a robot doing it. Sounds like a fun challenge. Might
have to spend some time on the physics to see if it's really possible.
UK Technogames a couple of years ago had a bicycle steered by the use of
thrusters. Essentially propellors on the front wheel.
Moving masses about would be problematic for the reasons given by
another poster unless you had a relatively large foot - that would
defeat (hey a pun :) the purpose.
If you could make a set of thrusters work that would be neat. Especially
if you used three just for the extra complexity.
I thought long and hard about exactly this kind of balancer a
few years ago, and came to the conclusion that you could do it
if you had a bi-directional knee joint with the motors, and at
the top of a further shaft, the battery pack. That way, moving
the knee in one direction displaces the motor mass in one
direction and the battery mass in the other, with perhaps
similar masses but different angular moment of inertia.
Try looking for the "inverted pendulum". Two variants (two links each)
are sometimes called the acrobot and pendubot.
Here are a couple relevant papers:
Are these what you wanted?
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