Chute Release and CO2 cartrige

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emre özkan

May 16, 2019
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Hi everyone. I'm building a high power model rocket. And i am planning to use 12gr co2 cartrige for recovery seperation. This co2 will seperate two boddies and both my parachutes will leave the body at the same time. Because of that i need to keep my main parachute as folded. For this job i made a diy chute release . In this mechanism i am using a servo , proccesor ,barometer(bmp280) and battery. It looks promising and all tests went okay. Except one of them. In final test when co2 deployed , barometer in the chute release sense this pressure change and release the parachute in the beginning.

So my question is " Have you ever used this configuration before?" , "How can I solve this problem?"

Thanks for all.
Whatever algorithm is polling your baro is too simple.

If I had to guess, your code is naively looking for a return to the baseline pressure plus an offset, which value was reached on the way down from the spike.

You want instead to look for a gradual increase in pressure AFTER the spike.
Okay I understand that. Thanks for the help. I'll try this.

Is chute release uses the same algorithm?

If not what if I want to use some sort of spring mechanism for separation? There will be no pressure spike.
I agree with dhbarr, fixing the code should be pretty simple, especially if you log the pressure data. I worked on a similar issue where I had to discriminate between two separate events that looked very similar to the sensor. Fortunately I had an audio sensor as well (along with IMU data) and I integrated that information to differentiate the two.

You know your ejection charge produces a very fast spike in pressure, followed by a return to pressure that was very similar to just before the spike. But you only want to release the chute after some period of gradually increasing pressure. So your code has to ignore the sharp spike from the ejection charge - if you give the issue some thought you should be able to code for that.

It gets challenging though when you start trying to account for flights that don't go as planned - like a CATO. Testing all the various possible scenarios is a challenge.

Good luck,