If your barometric sensor exposed on APM2.5?? Or you have tape/foam hack to cover it. Here is more elegant way to cover your baro nicely. On older APM2.0 baro sensor was covered with another PCB so it was not so exposed to wind blows and you got better altitude hold with it. On new APM2.5 board upper daughter board has been removed and barometric sensor is now fully exposed so it needs to be covered to avoid erroneous altitude readings.
We made custom APM2.5 Filter PCB for this purpose. It connects on both ISP pins on APM2.5 and foam on middle covers baro. There are additional +5V input provided on this board if you want to boost +5V system on your flight controller.
Ardupilot-Mega Wiki page has guide how to cover your baro but we were thinking that there has to be better ways than using tape and foam. Yes there are.
Which one you prefer?
Filter PCB's are now available on jDrones store, 4.5 USD each. So grab one during your next order and you will get a lot more accurate altitude response from your APM2.5 boards.
Jani / jDrones
Comments
Hello, does the new APM2.5 Cover not do the trick for this? or do you still required this PCB Cover with the Plastic APM2.5 Cover?
Thanks.
@Jani - Fully hear you there. I'm actually using the "Clear Spot" Band Aids...
I do change my BandAid after a few flights out at the field. Especially if dust is introduced to the board. I'm more concerned about Iron being picked and sticking to the Band Aid shorting the board vs the Band Aid itself shorting the board.
Scott.F don't feel :)
But becareful as some of tapes, bandaids can cause electronics problems as they can deliver small currents/voltages.
I can attest that getting the bvent holes int eh wrong place/too big on a rocket can be disastrous. But the basic point is to get to a point whether through foam or a bandaid (good idea, that) or a sealed chamber with a small hole, where any changes in pressure are gradual - essentially a physical low-pass filter for the air pressure. In the case of a plane, this should be easier since you can have the entire board enclosed and the airflow is more uniform. On a multi-rotor you get prop wash, wind, etc... on all sides, so it takes alittle more care.
And here I just put a band aid over my baro sensor. I feel so low tech :-D
@Patch
"calibrated holes"
I agree, that is the best way to make baro-based altm's work as advertised in nearly all conditions.
Good Idea and good design.
@Jani; lol..... I've had some fun border crossings, but its all legit. I have all of my certifications & licenses in order.
Maybe we can work on integrating your buffer design into the next style of APM 2.5 casing? It could easily be made weather resistant, and permit proper static pressure. I'll try and CAD up a new option.
Patch, have you ever tried to hand carry your cylinder in airplane?? Might get interesting on security checkpoint :)
Yeah rocketry is one really interesting area. I gotta keep my self out from that as running low on time even on current things.
Correct you need to be careful with airflows. Especially when having really fast planes. Pressure difference can be big depending on your flight position.
Just a note; if the fuselage cavity is being "force fed" air( like through an open port on the frontal area), or experiencing a slight negative pressure( due to open holes experiencing a venturi effect), the airspeed of the craft and angle of attack can cause enough of a pressure difference, to offset the barometer, even several meters or so.
Worst case? You dive the nose and increase airspeed, which could actually reduce pressure in the fuselage; the APM thinks it's going up, but it's not.
Food for thought.
PT
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