Well after much testing (where I never had a compass problem) the C8 (my baby) has been taken into the field to do a survey. And, of course, because it's very important that it work this time, it's not working. The report I am getting says that they calibrate the compass and it shows green in MKTool, then they calibrate the gyro for take off, and the icon goes red and MKTools reports Error 6: Bad compass value. They have gone through the compass - gyro calibration cycle multiple times in the field and it's the same every time. To add to the confusion, if they do it in a house it works just fine. So... the only thing I can think of is that it is cold outside, 10F with wind, and that maybe the compass doesn't work so well in the cold. Any thoughts?
Hi William: It sounds more like the place where they're trying to do the compass calibration has large masses of metal or something that's interfering with the compass? The reason that I'm saying that is it seems very odd indeed that it would not work in the field but works indoors -- the only difference being the magnetic field? I've not heard of any problems of the cold being a problem (except for the LiPos and the pilots, of course...) Andy.
Yeah, I have thought of that. There could be a lot of iron in the soil I suppose. They are in the middle of a huge field in the middle of no place so it's not power lines or pipe lines or anything like that. I have advised that they set the copter to ignore the compass on take off and then try a position hold to see if the compass is working in the air. I am assuming that it needs the compass to properly hold its position.
William might be that there is magnetic interference. If you run an MX-20 you can see whether the compass value is too low or too far misaligned with what the GPS thinks it should be. With the MK screen shown press and hold the SET button for a couple of seconds until the line at the bottom of the screen changes. It will look like the photo below. Mag % you would like close to or higher than 100. The incl value should be no greater than a 10 point difference. A wide spread might trigger the error message. Many times simply moving the copter where it is setting on the ground to another location will fix this. Example I can't launch from my front sidewalk due to the steel re-bar in the concrete. Same thing when calibrating the compass. Any iron/scrap metal in the area or even a cell phone turned on when you are holding the copter can mess up the calibration. Send some photos of your wiring setup for the batteries and a shot of where you have the NAVI and GPS mounted.
There could also be irrigation or drainage pipes, I suppose -- but that's pure speculation on my part. Andy.
Unfortunately, my kit from Quadrocopter came with a Spektrum DX8. They thought of that, and they moved the CS8 all over the place trying to get it to work. No joy. I don't have a picture on me, and I can't take one as the CS8 is hundreds of miles away at the moment. However, my member image shows how the navi and GPS are mounted. It's set up in the customary way. I run two batteries in parallel and they connect in the rear opposite from the GPS. It has flown many times without issue so I don't think it's how it's built.
Well it's not the cold. Because it's warm today and the problem persists. It has something to do with the site. At the house they are staying at it works, at the site it doesn't work. At the site when they power it up the compass icon shows red. Then they calibrate the compass at the site, and it shows green, then they calibrate the gyros and compass switches to red. It's kind of a mystery.
Are there any other sites that they can go to just to test this phenomenon? Maybe it is temperature related as you suggest...but an outside test at a different site would speak to that point.... Definitely a mystery....maybe they're discovered another Bermude Triangle? Andy.
No it's not the cold. It's 50 degrees today and calm winds. And it works at the house outside. They flew it a couple of times at the house. So it's the site. There is another site nearby that they could try it out at, but now the CS8 is complaining that it's not receiving an RC signal. They rebound the transmitter and receiver, but that didn't fix it. So the first expidition we sent the CS8 on is an epic failure. #@$%!
It's a Spektrum. But they got it working again. (Thanks to help from Quadrocopter support.) Apparently, when they were doing their 100th compass calibration they accidently switched the flying mode. The new flying mode wasn't set up, so the flight controller didn't realize it was connected to a Spektrum receiver. I suppose one thing I ought to do is configure all the modes exactly the same so this problem doesn't occure again. So, last I heard they were off to try flying at the other site.