How does a solid-state gyroscope work?

[Riscilla]

Hi everybody,

I think that I understand how classical gyroscopes work. But I can't understand how solid-state gyroscopes work. I have searched the internet for a good explanation of their principle of operation for several days but I've found nothing. I just don't see any relation between a classical gyroscope (with a spinning wheel) and a modern, solid-state one.

If you have time please explain it to me.

Thank you for reading my question.

Regards,

Riscilla.

 

[cesiumfrog]

Solid-state? Do you mean the MEMS thingies with microscopic spring-pendula?

 

[DannoXYZ]

Or do you mean a 3-axis accelerometer using gels?

 

[rcgldr]

Radio control models, normally RC helicopters, use a single axis gyro to assist with the tail rotor. These use a piezo crystal yaw detector, or a vibrating part on a silicon wafer. The "heading hold" gyro's allow the rc helicopters to hold a heading or maintain a yaw rate in spite of side loads on the tail rotor due to flying sideways.

http://www.rchelisite.com/how_do_gyros_work.php

http://www.rchelicopterfun.com/heading-hold-gyro.html

 

[Riscilla]

Solid-state? Do you mean the MEMS thingies with microscopic spring-pendula?

Well, I mean the gyroscopes whose operating principles are based on the coriolis force

 

[f95toli]

Solid-state gyroscopes are -as far as I know- essentially just miniature versions of ordinary gyroscopes, i.e they are still based on something moving.
With modern technology we can make these moving parts very small, but a micromechanical (=MEMS) gyroscope is still based in principles that goes all the way back to Newton.

 

[Cleonis]

Well, I mean the gyroscopes whose operating principles are based on the coriolis force

Well, rotation sensing is a subclass of acceleration sensing in general, and all acceleration sensing is in one form or another sensing of inertial effects. In that sense gyroscopes and solid state sensors do go back to the same principle.Concentrating on rotation sensors: whereas a traditional gyroscope works with rotation of the moving part, solid state sensors work with vibration of the moving part.

The simplest kind of vibrating part rotation sensor is a single rod. Actually, the first to describe the observation was Foucault (known for his Foucault pendulum)
Foucault had clamped a rod in the chuck of a lathe, he twanged the rod, and he slowly turned the lathe. Interestingly, the plane of vibration of the rod maintained its direction. The conclusion had to be that the inertia of the motion is not locked to the material of the vibrating rod; in that sense the direction of the plane of vibration is immaterial.

So if you design a casing with three vibration rods in it, pointing in three perpendicular directions, then you can always infer the overall rotation. Another example is a design that works with a ring.
The vibration that is set up is one in which the ring remains planar, but the vibration deforms it to elongated shape. The vibration has four nodes and four anti-nodes. This vibration pattern has a directionality: you can detect where the nodes are.
Interestingly, if you rotate that ring physically, the immaterial direction of vibration is conserved. It's a form of conservation of momentum.
Again, with a design with three rings perdendicular to each other, you can always infer your overall rotation.

The first rotation sensor that operated on the basis of vibration was the Foucault pendulum. In the following article on my own website I discuss http://www.cleonis.nl/physics/phys256/foucault_pendulum.php"

Cleonis
http://www.cleonis.nl

 

[cesiumfrog]

Or do you mean a 3-axis accelerometer using gels?

How are gels used? (Fabrication, damping, or actual operation?)

 

[Riscilla]

Thank you all for your detailed answers. Now I already understand the problem. :)

Regards,

Riscilla.