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Terry

Temperature Stabilisation

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I am 'playing' with a cheap GWS gyro but I find the neutral position changes with temperature. Has anyone been successful in adding temperature compensation to a gyro ?

The two ideas I have are to add a thermistor to adjust the neutral point voltage or to make the whole unit work at a fixed temperature with a heater.

Terry

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Is it the PG-03, and how are you using it? The sensor alone, or using the gyro's circuitry? There's a reference output on the sensor that is supposed to represent the output for zero rotation and have the same variation than the rate output.

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Is it the PG-03, and how are you using it?

No it's a cube shape one with no name on it. So far all I am doing is monitoring the red/green LED the goes off when the gyro is correctly set to neutral. At the moment it goes red when warm and green when cold.

There's a reference output on the sensor that is supposed to represent the output for zero rotation and have the same variation than the rate output.

I think I know what you are saying :unsure:

I have found a pin that changes voltage as the gyro is turned. This pin changes voltage by 0.05v when moved from a cool room to a sunny window.

Terry

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OK. There should be a second pin that has a constant voltage with regard to rotation, but whoud have the same voltage variation over temp.

I don't know what you have in your unit, but the PG-03 uses a Murata ENC-03J sensor. They were using the typical circuit mentioned in the datasheet where the output is sent into an opamp along with the reference, which compensates up to some extent. But the sensor is indeed pretty bad, I tried using it for a headtracker long ago, and it seems most attempts to do something long-term with it are doomed.

BTW, the same sensor is used on the mikrokopter, and I'll indeed have to trim the yaw axis (which is head-lock as for a heli) several times throughout a flight. Pretty much what I had observed with my own things.

Edited by Kilrah

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Has anyone been successful in adding temperature compensation to a gyro ?

The first hobby gyro I ever came across that had temperature compensation was the CSM360, the first heading hold. I recall they glued the thermistor to the sensor body. They claimed that the factory calibration took over one hour on each gyro (I think they had to bake the gyro at several temperatures and store cal constants in its E2Prom).

The oven idea might be easiest. Or, use a more expensive MEMS based hobby gyro.

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There should be a second pin that has a constant voltage with regard to rotation, but whoud have the same voltage variation over temp.

OK, found the pin you mean but there seems to be an error voltage between these 2 pins that changes with temp.

Maybe I will glue a thermistor to the gyro and use the output from that to compensate the value using a look up table in a pic as Mr RC-Cam said.

use a more expensive MEMs based hobby gyro.

Can you give any more info on this, dose it not suffer from temperature ?

Terry

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The typical MEMS gyro sensor IC has an internal temperature sensor for just that use. But, the installation still requires a bit of external circuitry and calibration at various temperatures. All this is handled for you if you use a high-end hobby gyro, like one of the newest Futaba offerings.

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I see, those gyro's come at a high price though and for what I want to do I don't think it would be worth while. Are the sensors availible for a fair price or is there a second hand gyro I should be looking out for on ebay ?

Terry

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The MEMS gyro sensor IC is expensive. Sparkfun.com has some little boards to offer. The bare IC is less costly, but they are not hobby-solder friendly. Used (or gray market) Futaba MEMS heli gyros will set you back about $100. So, I agree, they are expensive. But, they do work nicely.

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