According to Randy the know issue of altitude loss after a high speed run is at its heart a frame issue.This seems to me a very worthwhile discussion to have.Once the majority of us understand this, we will be less likely to muck up other threads.Take it away Randy...
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Ah, you might have to be careful about the voltages supplied to the baro. The Pixhawk's I2C port provides 5V power although the signal levels are all 3.3V. So just need to make sure that the external baro board has a regulator that can accept 5V for it's power source.
2. make a cable to plug it into the Pixhawk's I2C port correctly (see this wiki page)
3. load up the "latest" Copter firmware by pressing Ctrl-Q on the MP's install firmware page (sorry, dual baro's not supported in Copter-3.3, but will be in Copter-3.4 which will begin beta testing later this month)
4. set the GND_PRIMARY to "1" to use the external baro (switching it back to "0" will make it use the internal baro which uses SPI by the way).
I think Chris’s idea of isolating the baro has a lot of promise for a couple of reasons. #1 it negates the issue of large numerous openings on the pixhawk. #2 it opens up the possibility of being able to easily modify the input source for air pressure via simply moving the air hose around on the DIY frame until you achieve the desired results and or installing a ’T’ and providing a source of air from more than one location which I have personally found to be the key. That old adage ‘KISS’ keep it simple stupid might well apply here. The ease of which the baro could be isolated and shipped with a small nipple ready for the consumer to use small rubber fuel tubing [ or a minor mod by the user like JoeBob did ] and adjust as needed might work better than trying to work a miracle with code. Because of the million different set ups involved in the DIY type platform it might prove to be just that… a miracle. At the very least the code would probably require a set of adjustments to accommodate the different frame / set ups it seems. I can see a 1500 page thread on people trying to get that set up…. moving a hose is simpler. IMHO of course.
I understand the nature and mechanics of the discussed issue, but why on the earth primitive Naza doesn't suffer from this?!?! there gotta be a logic solution to this problem.....
Are you referring to the naza in general or the phantom? The phantom of course is inside an enclosed shell but has leaks available all over which is perfect. Have you ever tried a naza on an open type DIY type frame? Many of the frames DIY people use set the controller on top of a flat surface that then acts like an air ram of sorts in fast forward flight over a wide open controller creating a higher pressure all over the board which explains why it then shoots way higher because of the higher pressure it thinks it's lower than it was. At least that's been my impression but if a naza works fine on the same frame as a pixhawk had a problem with then I guess it really might just be too many large openings in the pixhawk. I'd be curious to know which it is I suspect it's a little of both.
Replies
Randy,
Any info you can provide on the external baro requirements? Does the EKF fuse the two baro sensors, or do you need to disable one in the code?
Ah, you might have to be careful about the voltages supplied to the baro. The Pixhawk's I2C port provides 5V power although the signal levels are all 3.3V. So just need to make sure that the external baro board has a regulator that can accept 5V for it's power source.
This is great, thx !.I always got in trouble covering the internal baro w/o covering its "hot" neighbours as well, so this is a fine alternative.
Btw. The board you linked to, is called GY-63 and its coming with a low drop LDO advertised for 3-5V operation.
Mike,
After a quick check with Tridge, the easiest way would be to:
1. buy an I2C based MS5611 baro (probably like this one)
2. make a cable to plug it into the Pixhawk's I2C port correctly (see this wiki page)
3. load up the "latest" Copter firmware by pressing Ctrl-Q on the MP's install firmware page (sorry, dual baro's not supported in Copter-3.3, but will be in Copter-3.4 which will begin beta testing later this month)
4. set the GND_PRIMARY to "1" to use the external baro (switching it back to "0" will make it use the internal baro which uses SPI by the way).
I think Chris’s idea of isolating the baro has a lot of promise for a couple of reasons. #1 it negates the issue of large numerous openings on the pixhawk. #2 it opens up the possibility of being able to easily modify the input source for air pressure via simply moving the air hose around on the DIY frame until you achieve the desired results and or installing a ’T’ and providing a source of air from more than one location which I have personally found to be the key. That old adage ‘KISS’ keep it simple stupid might well apply here. The ease of which the baro could be isolated and shipped with a small nipple ready for the consumer to use small rubber fuel tubing [ or a minor mod by the user like JoeBob did ] and adjust as needed might work better than trying to work a miracle with code. Because of the million different set ups involved in the DIY type platform it might prove to be just that… a miracle. At the very least the code would probably require a set of adjustments to accommodate the different frame / set ups it seems. I can see a 1500 page thread on people trying to get that set up…. moving a hose is simpler. IMHO of course.
I understand the nature and mechanics of the discussed issue, but why on the earth primitive Naza doesn't suffer from this?!?! there gotta be a logic solution to this problem.....
Are you referring to the naza in general or the phantom? The phantom of course is inside an enclosed shell but has leaks available all over which is perfect. Have you ever tried a naza on an open type DIY type frame? Many of the frames DIY people use set the controller on top of a flat surface that then acts like an air ram of sorts in fast forward flight over a wide open controller creating a higher pressure all over the board which explains why it then shoots way higher because of the higher pressure it thinks it's lower than it was. At least that's been my impression but if a naza works fine on the same frame as a pixhawk had a problem with then I guess it really might just be too many large openings in the pixhawk. I'd be curious to know which it is I suspect it's a little of both.
IMO, the casing is the key. You want really tiny openings, really, as little entryway as possible.
All the large openings on the Pixhawk act like air scoops. Think "Ram Air" for cars.
wow great idea
So, the key is for someone to make a naza style Pixhawk with no "beloved" df13 ports and a tight case for it? Sounds almost like an auav-x2?
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