Need help understanding a concept in Gyroscopes

[ME101]

So I've been trying to understand a concept in gyroscopes and I hope the guys and girls here can help me with it.

I first read it here, the part about mounting 2 gyroscopes with their axes at right angles to each other. It said that the platform will remain totally rigid.

I tried to consult a few of my teachers about this but none of them seemed to have an answer why. I've been searching online and the closest I came to finding something that relates is an old US patent No. US3398586. Fig 1 seems to be working around the same concept.

So does anyone here know why this happens? Any help would be greatly appreciated. Thank you and have a great day.

 

[jedishrfu]

Not sure if this is helpful, but it talks about using gyro and the Earth's rotation to make a stable platform:

http://en.wikipedia.org/wiki/Gyrotheodolite

 

[Baluncore]

No forces may be transformed by the gyroscopes, without causing precession. The platform with the two gyroscopes must therefore be free to rotate space, or mounted in gimbals on a vehicle.

One gyroscope can give you a single reference axis direction, relative to the stars. It takes a second gyroscope, with an axis that is not parallel with the first, to resolve another direction. Given those two axial directions you know platform orientation relative to the stars.

A vehicle can be made to remain stable by sensing vehicle orientation relative to the gyro platform and applying torque to the vehicle to correct the vehicle orientation.

 

[ME101]

Hi Baluncore and thank you for your response. I just want to know that if two gyroscopes with perpendicular axes are mounted on a platform that is in turn mounted on gimbals, will the platform maintain its orientation in space such that the gimbals rotate? If it does, why does that happen?

 

[Baluncore]

Yes, it will be stable, but only if it is precisely balanced, has no friction in the bearings and is operated in a vacuum.

It must obey principles of conservation of energy and momentum. Without some external force being applied there can be no change in orientation. http://en.wikipedia.org/wiki/Gyroscope#Properties

It turns out that a gyroscope's frame of reference is the same as the stars. It is called a “gyroscope” because it was originally intended to demonstrate that the Earth rotates. http://en.wikipedia.org/wiki/Gyroscope#History