Revo GPS nightmare! Please help!
« on: August 23, 2016, 10:10:17 pm »
I'll try to make this short and to the point: I really like the CC3D and the Revo with GPS turned off. But, for the life of me, I cannot get GPS to work correctly. I've done all the calibrations 20 times to where the horizon is level and all meters are green. I get 13 satellites with my Ublox GPS puck pre-configured for Revo plugged in.

But, at this point, it will either not arm at all or else if it does arm, as soon as I lift off the quad banks extreme and flips over. I ran into the side of my house and broke off the GPS mast at one point

Sometimes horizon is all over the place. Only a few times is horizon steady. MAG always wants me to re-calibrate. It's never happy for long.

NOTE: It flies very well with GPS turned off so I don't suspect engine, vibration, ESC, etc. issues.

Please help!

Storm Type-A Frame
Taranis with Crossfire
Revo with Mini Ublox Neo-6M GPS
Another person with similar problems (also see Youtube thread below the video):
« Last Edit: August 24, 2016, 02:03:36 am by VoicOfReason7 »

hwh

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Re: Revo GPS nightmare! Please help!
« Reply #1 on: August 24, 2016, 05:58:53 am »
Your video shows the mag as red, you can't use the gps modes without perfect, green mag.  It can't go red even at full throttle.  I can't tell from the video whether the gps has a mag in it or not.   It's almost impossible to get the revo's internal mag calibrated and working because the revo is mounted too near the power wires.  If the gps does have a mag it's mounted in a bad position out on an arm near the magnetic field of the motor.

Wagsy

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Re: Revo GPS nightmare! Please help!
« Reply #2 on: August 24, 2016, 06:06:17 am »
Yes your mag is red, make sure you are using a external mag and not the mag on the REVO board itself.
If you get good green mags, it will boot up and arm super fast every time.
Calibrate it outside, getting a good green mag cal is the key to making it work.

chromvis

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Re: Revo GPS nightmare! Please help!
« Reply #3 on: August 24, 2016, 07:09:13 am »
Which GCS version you are using? Is it 15.09? If yes, it does not support AuxMag and UBlox GPS, only "next" version does, and there are still some difficulties with external mag calibration.
Model behavior in your video is typical for errors in mag calibration and overall system confusion due to sensors dissonance in INS13 mode.

hwh

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Re: Revo GPS nightmare! Please help!
« Reply #4 on: August 24, 2016, 07:12:52 am »
.... it does not support AuxMag and UBlox GPS, only "next" version does...
The 15.09 release doesn't support AuxMag but all versions support the UBlox GPS units.

Re: Revo GPS nightmare! Please help!
« Reply #5 on: August 24, 2016, 05:13:27 pm »
Actually, the video above is NOT me as I stated, but his problem is so similar to mine that everyone's advice still applies. Wow. So, maybe I need to consider a different FC if I really want to use GPS features?

f5soh

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Re: Revo GPS nightmare! Please help!
« Reply #6 on: August 24, 2016, 05:25:57 pm »
You can simply assume you cannot got the onboard Mag working on a small (250mm ?) frame.
All power devices are too close and create strong magnetic fields.
A simple Lipo saver can disturb the Mag.

Whatever the board you plan to use you need to setup a external Mag.
You should use the "Next" GCS version that support I2c Mag or better Naza GPS providing GPS data and Mag data using the same connection.
 

jtrout19

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Re: Revo GPS nightmare! Please help!
« Reply #7 on: November 19, 2016, 03:59:37 am »
just curious, why is there a internal mag on the revolution if it cannot be used?

hwh

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Re: Revo GPS nightmare! Please help!
« Reply #8 on: November 19, 2016, 06:05:53 am »
At the time it was designed they didn't know how bad the interference from power wires would be.  And it is usable on some big 450-550 size frames if power wires are done carefully.  Unfortunately most of us have gone in the opposite direction and are using 250 and smaller frames.

Re: Revo GPS nightmare! Please help!
« Reply #9 on: November 19, 2016, 02:30:30 pm »
Nightmare is the best description of this whole thing I've heard of yet!  I'm just about to walk away from this whole thing.  The idea of "building your own" quad is a few generations of equipment away from being at a reasonable state IMHO.  WAY too many compatibility and functionality problems with all these FC, GPS, OSD, ESC, Camera, Video TX/RX, motor, and batterie combinations (oh, and don't forget about good quality firmware for all the above.)  You darn near have to be a double major in electronics engineering and computer science to make all this work.  We're certainly not in a "plug and play" world yet... far, far from it.

My best reco is... buy a commercially engineered unit that already has ALL the features you want.  Hopefully if someone is willing to put their name on it... it's "good to go".

I've been working with my Revo for a couple of months now.  After trying GPS modes totally unsuccessfully (and ordering a "good" GPS advertised with a compass that didn't have a compass) I went back to non-GPS modes.

Even there I couldn't even get a successful "board level" calibration.  I'd "save" position once, rotate 180 degrees, save again.  Then as soon as I'd reboot the board, I'd watch the horizon go up and into a turn, predictably EVERY TIME.  The only way I could fly it was in Acro+ mode (where it doesn't need to know what "level" looks like).

The only thing that seems to have helped is doing the temperature calibration.  I stuck the whole thing in the freezer for an hour or so as directed by some posts, and let it do its thing.

I now get a "pretty good" but still not perfect flat calibration.  "Level flight" still requires a lot of manual control just to stay close to position, even with no wind.

I could go on about this extremely frustrating journey, but that's about the only helpful suggestion I have for you at this point.

Good Luck!

P.S.  I find it "interesting" that PAINLESS360 has yet to post his final 6/6 video on REVO with GPS flight.  Been quite a while now.  My only guess is that he's having issues getting it work "rock solid" as well.

Re: Revo GPS nightmare! Please help!
« Reply #10 on: November 19, 2016, 07:14:26 pm »
Isnt this exactly what it makes so funny and interesting?  ;D You learn a lot of stuff and sometimes you get an achievement  :D

I think many revo clones have just bad hardware...so you never get this thing working...

Anyway i also needed two weeks to get a revo clone flying in altitude hold mode. And now trying gps assist modes...seems that this will cost me a month :-)....but normal attitude mode works just out of the box without adjusting anything...

But youre right if you dont want to investigate your time in such a complex machine you better buy a commercial one...
« Last Edit: November 19, 2016, 07:17:39 pm by DocHardinger »
Hardware: F450 Frame--Revolution Board--EMax 2213-935kv--BullTec 30A Opto--5000mAh 3S 30C LiPo--NEO M8N GPS+MAG--Fr Sky Taranis Plus + OPLink Mini
Addon: sj5000x + two axis gimbal + minimosd + eachine VT + easycap
Software: Black Rhino, LP2GO

jtrout19

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Re: Revo GPS nightmare! Please help!
« Reply #11 on: November 20, 2016, 05:18:45 am »
I will comment on this. I had a horrible time as well. And yes it is a journey and a complicated one. But I will say this I am still under cost wise what I would of spent on a nice commercial drone. And the knowledge I have gained is priceless. I think I finally have my issues solved and we will see tomorrow. The latest things I have learn is on some revo clones there is a ceramic cap that is the wrong value on the bypass pin of a voltage regulator that powers the barometer. It makes your barometer values wonky. I was having that issue. Removed that cap and now I have less than a half a meter of drift in my scopes.

Second thing I originally bought a ublox neo 6m. Did some things with it. Never could get the mag quite right. Got really fed up with it ordered a genuine naza gps. That got here tonight. Hooked then up powered my quad and got a lock inside my house in less than 5 minutes. For shits and giggles I did a mag calibration in my house (I KNOW I KNOW) i did it just to see. I got better mag_transform values than I have ever gotten and, at one point I dressed all in sweats took my wedding ring off and walked a half mile into a corn field to do the calibration. I had my wife operating the computer. I would always be about .20 off in some value. Take a look at my values when doing it in the house!

Code: [Select]
1.02931  1.01459 1.0953

Yeah so if this doesn't work my next step is going to be to build a revo. Not buy a clone but order the boards and components and build the thing myself with the components that were originally supposed to go on it. I know there are "good" clones out there, but if a company decides to clone a precision electronic and lets say they use 5% resistors instead of 1% resistors or use a 100pf caps instead of 82pf.....the list goes on, but if they do this then small issues creep up. Something doesnt work quite right or doesnt calibrate right cause the sensor is supposed to see this voltage or that capacitance on this pin or that, and it throws everything off because on these flight controllers everything works together.

Also small details like barometers being super sensitive to light....is not right out there in the open. After I learned that I build a small box that now my baro rests in. No light, no airflow. Just a teensie little hole and I am talking tiny to allow pressure changes to happen inside the box. That coupled with the resistor thing fixed my baro issues.

So I would go out and fly tonight but the reelfeel temp where I am at is 9 degrees. Supposed to be 40 something tomorrow. So tomorrow is the day that I find out if my stuff works. If it does I will post a video and let everyone know.

Mateusz

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Re: Revo GPS nightmare! Please help!
« Reply #12 on: November 20, 2016, 10:22:43 am »
I think you should plan first what you want to do in RC hobby.

  • If you want working out of box "push a button" filming platform, then DJI Phantom line is what you are looking for.
  • If you want race, then build your copter and use Basic flying modes.
  • If you want an autonomous flying and DIY copter then it is a completely different story and you will need to learn a lot period.

Why ? Because every DIY copter is different, it's not mass production that can be tuned, optimized and all is the same. Software has to handle all wired things user may come up with and yet work reasonably well. Most of problems come from lack of knowledge which is related to NOT reading, or not willing to read Wiki combined with huge expectations that everything will magically work.

There are two most common fallacies that people fall into
  • Quad-copter is not flying well in Basic complementary (this uses just gyro and accel in attitude mode)
  • Quad-copter is flying well in Basic complementary but other sensors are not calibrated properly.

To begin with (1). Flying with Complementary that uses just two sensors is easy. It should work out of box if your build is solid and well balanced. For example I can hover 1-3s in place (without wind) even put transmitter on grass and pick it up, without huge drift of copter position. I am not using any crazy super-duper sensors here, just good solid well balanced and calibrated build.
If your copter is not flying well in Complementary (Basic) then it will not fly better with GPS. Why ? Because you have more basic problems and by adding GPS you attempt to add complexity on something that is not working. GPS won't magically fix that. Why ? Because autonomous flying is NOT just using GPS alone. GPS alone has humongous (huge) error of couple of meters and can suffer from multi-path reflections other sensors are needed to help it.

Here it's (2) point. All and absolutely all sensors are needed and deliver non-replacable information. Those different sensors are not there just because someone wanted higher board costs but because they measure completely different things required by autonomous system. You can't have one sensor not working and think something will compensate it, this won't happen. For example GPS does not know heading, only magnetometer knows. Revo has built-in magnetometer and it works if you put your board far from wires, or you have big copter (like in old days) where most wires that are twisted go far from the board. On <300mm builds this is no longer true. You need external magnetometer to use it. Built-in mag is still useful to determine correct mag rotation in GPS unit though. Not working Mag is usually cause of moving horizon when copter stands still.
Another sensors is barometer, it should also be well calibrated and altitude-hold function must be working properly, for autonomous flights using GPS. When you turn on GPS functionality, you must be sure, all sensors are functional as expected.

Problem is that most people come to this hobby, and assume that GPS alone gives good estimate, I think it might be related to smart-phones analogy. However, even smart-phones use sensors, gyro, accel, mag and wiresless network, wifi, nearby devices to improve accuracy of estimated position on the map. This is not just GPS alone.
Secondly, people have expectation that building DIY from not necessarily well picked components, should be easy, perhaps someone not knowing even what fail-safe modes settings are should be able to operate DIY copter. Definitely NOT, you really have to know what you are doing, read, learn and be responsible, not to cause more harm to other people in this hobby. 

I hope this calms damn a bit topic which is in my opinion exaggerated. People here are not any commercial company giving support for their product, everyone here is friend, trying to help you when they have spare time. But it's your responsibility to learn how to assemble, tune, operate DIY copter. We can't force you to read instructions after all.

What I like about this hobby, is that I learn a lot, and I can come up with my own improvements, that's what DIY hobby is, right ? Tinkering, learning, experimenting. Lots of fun is spend on building, customizing and I think that's where this project stands up in contrast to more ready-to-fly solutions such as DJI. I have full respect to DJI pilots, their engineers and programmers as they have a really smart team, the only difference is that they're targeting different niche and cover just one type of pre-assembled always the same hardware.
 
;)

ggrif

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Re: Revo GPS nightmare! Please help!
« Reply #13 on: December 02, 2016, 04:43:41 pm »
Mateusz, indeed, +1 😜!!

Getting GPS to work well is not for the lazy, it takes a lot of reading and work. And it may never work well for a particular frame, especially 250 and below.

If a person is really interested/challenged, it can be done. And it gets easier with each frame cause you learn what not to do as well as what to do.

Re: Revo GPS nightmare! Please help!
« Reply #14 on: January 06, 2017, 07:25:24 pm »
Mateusz, indeed, +1 !!

Getting GPS to work well is not for the lazy, it takes a lot of reading and work. And it may never work well for a particular frame, especially 250 and below.

If a person is really interested/challenged, it can be done. And it gets easier with each frame cause you learn what not to do as well as what to do.

Hey guys, I was pretty frustrated when I made my previous reply.  I value learning and the ability to customize.  I've been building and designing fixed wing for decades.

Pardon my frustration, but there does come a point when it seems there is no way to make something work.

I did buy a knock-off camera drone for now, and back to trying to get my DIY hybrid drone working as desired.


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