B Control moment gyroscope design - question

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1. Aug 9, 2015

stencilman

Hi all,

Like a lot of folk on here I am interested in the idea of a CMG used to stabalise a single track vehicle.

<< Link to CMG info added by Mentor >>
https://en.wikipedia.org/wiki/Control_moment_gyroscope

I have designed this;

the pink discs spin in opposite directions and the pendulum rotates them.

My question is could this replace a complex control system? or am i making it to simple?

(i tried to simulate it in SW but have not got the premium license)

keen to hear your thoughts

tom

Last edited by a moderator: Aug 13, 2015
2. Aug 13, 2015

stedwards

I don't understand. The pendulums swing in opposite directions. Is this intentional?

3. Aug 14, 2015

stencilman

it is just one pendulum joined with a pin. (i could have made that clearer)

4. Aug 14, 2015

stedwards

Though your intent is not clear, I don't think it's going to operate as you wish. If the assembly tilts 5 degrees what happens? In which direction do things move?

5. Aug 14, 2015

stencilman

my intention is that the frame should be rigidly bolted into a motorcycle frame.

when the motorcycle stops the pendulum provides a negative feedback system tilting the counter rotating gyroscopes so that the rider never has to put his feet down.

6. Aug 14, 2015

stedwards

OK, so the axis at the bottom of the box is inline with the long axis of the motorcycle, right?

Then, with the way the gyros are gimbaled, you're counting on the procession of the of the gyros to move the pendulums. I'm not sure how the angular velocity could effect pendulum displacement.

7. Aug 14, 2015

stencilman

I think you see what I am trying to do.

the pendulum is acted on by gravity and g force and it dictates the gyros position.

"I'm not sure how the angular velocity could effect pendulum displacement." - if by this your saying the gyros may try to move the pendulum (equal and opposite) then I am not sure either.

on this Wikipedia page a similar system is discussed under principles of operation;

https://en.wikipedia.org/wiki/Gyro_monorail

what i am trying to find out is can a simple mechanical linkage/mechanism replace what lit motors are doing with software/complexity.

The above links and below seemed to without software.

8. Aug 15, 2015

stedwards

It's interesting what you are trying to do. The modern approach is to use some electronics feedback to obtain stability.

Consider the limits. When the gyros are spinning at zero angular velocity, the pendulums don't move at all. In some classical limit of high angular velocity of the gyros, the pendulums will move to their limits.

Somewhere in between, a full dress Harley might slowly tip over waiting for the light to turn green.
Then you've got to correct for the lean coming out of the red light. It won't do If you have to
change lanes to do it. I think you just have to try it to see how how it handles. It might suck in the turns. So go for it, and see how it handles. It could be really stiff; impossible to turn. Put a prototype on a bicycle so your friends can laugh at you.

Last edited: Aug 15, 2015
9. Aug 17, 2015

stencilman

i think i understand what your saying; - your concerned the gyros wont always return to center.

on the wikipedia page i referenced there is the figure of 5% of total vehicle mass required for gyros. we had the same idea, first i will check it on SW at work then if it seems workable i will make up a little prototype, say a pair of 200mm diameter 10mm thick steel discs (2.5kg each) at say 5000 or 9000rpm. (depends on which motors i buy) and bolt it to the back of my bicycle (in a sturdy box!)

would you say its better to mount them lower or higher?

10. Aug 17, 2015

A.T.

A differently loaded vehicle will need different gyro action for the same lean angle. How would pendulums, affected only by the lean angle, account for this? And since the gyros have to be powered anyway, what is the point in removing the powered control system?

11. Aug 17, 2015

stencilman

I think the pendulum will provide a negative system

12. Aug 19, 2015

stencilman

A japanese gentleman makes these for a hobby;

notice how they seem to lean like a bike into the corners.

13. Aug 19, 2015

A.T.

14. Aug 20, 2015

stencilman

15. Jan 5, 2017

ibrar

what is mobility of this mechanism?

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