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29 November 2024 03:48
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Question |
| Asked by: |
Alexandr Leniv |
| Subject: |
Information about Coriolis vibratory gyroscope (CVG)??? |
| Question: |
Hi! I need your HELP!!!! I need to get information about Coriolis vibratory gyroscope: descriptions, principles of work, photoes, diifferent kinds of CVG. It's for my science project into my university. But I cann't find such full information. Please HELP me!!!!!! |
| Date: |
10 December 2006
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Answers (Ordered by Date)
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| Answer: |
Todd Blackmon - 12/01/2007 00:32:43
| | | I would suggest that you look at Analog Devices for some information, but I didn't see any that would interest you. However, they did a lot of the work bringing these to market. The ADXRS300 is an example.
Working Principle. coriolis vibratory gyroscopes work because of coriolis force.
This is best explained by example:
Imagine you are standing in a room with no windows that is spinning. There is a dot on the floor 10' in front of you that is the center of rotation. When you are in the spinning room you are looking at the world in a 'non-inertial frame of reference'. From your point of view the room is not moving at all. However, if an observer outside could look at you, they would say you were spinning. They are in an 'inertial frame of reference'. Newtons laws only apply in an inertial frame of reference. In non-inertial FORs, other forces show up. These are called 'inertial forces'.
For example, in the inertial FOR, by staying in place, you are going to lean forward (towards the center) to force yourself to the center because you want to stay in the same location (from your point of view). You are providing centripetal force so that you will move in a circle. But your don't really feel this. Remember there is always and equal but opposite force. This is the one you feel. It is called centrifugal force.
To get back to coriolis force, since you are about 10' away from the center of rotation, every time the room spins around you travel about 63'. If you were to step in closer to the center, let's say a 2' step, you would travel about 50'. Since you travel these distances in the same time (the time for one rotation of the room), you are traveling less distance in the same time, so your are slowing down. So by moving straight to the center (from your point of view), you are moving slower to the inertial POV. Again you are applying this force. If the room was going clockwise looking down, you would be accelerating yourself to the right. But again you don't feel the force you supply but the equal but opposite force, so you feel a force pushing you to the left. This is coriolis force.
In a CVG, the room is the gyro housing, and you are the vibrating mass. Since you are moving back and forth towards and aways from the center, you will feel a push one way then the other. The amount of push depends on the spin rate. The mass is connected to springs that center it. So it will get pushed by coriolis force to the left and the right of the spring depending on direction, and the amount of distance is determined by the spin rate again. They measure this distance, and it tells the amount of force that is used to tell the rotation rate.
For the people who really want to know, these are usually called MEMs sensors, the spring is actually a silicon spring, and the distance is measured using teeth on each end of the mass. The teeth fit between teeth in the housing, and the distance between the edge of the two sets of teeth causes a capacitance. The capacitance is proportional to the distance, and can be measured down into the fempto-Farads, that is 10^-15 Farads. The mass is vibrated by a piezo-electric response.
Sorry, I don't know where to find any photos, though. Hope this is enough.
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