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Discussion in 'Electronics' started by Colin Snow, Jan 23, 2013.
Here's the data under load (with gimbal and camera).
Crazy, crazy, crazy....
MK Version: FC HW:2.1 SW:0.88e + NC HW:2.0 SW:0.28h
Flight time: 1:24:28 PM - 1:29:55 PM (327 secs, 00:05:27)
Total: 328 secs, 00:05:28
Elevation(GPS) : 0 2.44 4.45 m
Altitude(Barom.): -0.7 5.52 7.55 m
Vertical speed : -1.17 -0.02 0.82 m/s
Max speed : 15.2 km/h
Max target dist.: 9.5 m
Sats: 8 11 12 (min/avg/max)
Voltage: min. 14.3, max. 16.6 V
Current: 18.2 43 51.9 A
Wattage: 302 647 772.2 W
Capacity: 3932 mAh
Motor1: 1.2 8.5 13.0 A Temp: 28 66 82 °C
Motor2: 0.3 3.1 4.3 A Temp: 26 62 76 °C
Motor3: 2.1 8.4 11.5 A Temp: 27 67 80 °C
Motor4: 1.5 6.6 8.3 A Temp: 28 67 81 °C
Motor5: 3.5 9.1 11.9 A Temp: 31 75 87 °C
Motor6: 1.6 5.8 8.3 A Temp: 28 60 71 °C
Magnet Field: 99 100 105 % (ok)
Magnet Inclination: 58 60 64 deg
No errors found
Dave - Thanks for showing this. Looks easy enough to build.
Ziggy at MK.us had this to say about the odd motor issue:
"Its your compass, we'll probably your Lipo wires.
move your lipo wires, make them short and straight as possable,
tie wrap them so the red and black do not seperate, or
better yet heat shrink them all the way form the lipo to the plug and from the plug to the power dist board.
also a good test is to fly with out your navi and see if it does the same thing.
but what happens is its fighting some EMF and always trying to Yaw against it, to yaw it slows down every other motor, and the others work harder. Some how though when this happens it never seems to yaw it just thinks it has to.
another fix is to get your Navi board as high in the stack as you can , sometimes its just really one small move of a lipo wire or raising the Navi that fixes it.
your lipo wires should go straight down and away a fast as it can away from the FC and Navi."
So I want to fly without Navi but still record data. How do I do that?
Please keep in mind that Ziggy probably assumes that you are stacking your navigation board onto of your flight control board. In the freefly kits the navigation board is moved over to boom one to rectify this. Can you post a picture of your lipo and battery wires? I also believe that you can have the same type of symptons you are experiencing if you have a bad compass calibration. Before fliying without the navigation board I would try to eliminate any lipo wire issues and also to recalibrate the compass. It helps when the props are off. Also make sure you do the compass calibration away from all metal objects and to do it in a nice space 50 feet away from anything. Make sure you cell phone is not in your pocket when you do the caibration.
BTW: You can't log data if you do not have a nav board functioning.
Furthermore, you won't get a log if the Nav board doesn't get a GPS fix. I found that out recently when I was flying indoors at Moscone Center. I was expecting no GPS or compass assistance, but I didn't realize that the MK Navi board logger won't even write a log if the GPS doesn't get a fix. Kind of bummed about that because, although the flights went very well, I wanted to see the data.
I appreciate Dave (and everyone's) suggestions and input. Here's some pics.
What I have done so far is:
Replaced Motors 2 and 5 with new one
Balanced all props and hubs
Braided motor wires for booms 1, 2, and 6
Straightened all motors
Re-calibrated compass (free and clear)
Twist and heat shrink Lipo wires
Moved potential EMF producing wires away from Navi stack
Things I have not tried yet:
Braid motor wires on boom 3, 4, and 5
Move the OSD to bottom of the Navi stack
Move the TM100 to sit between booms 5 and 6
Drink more alcohol
Become an monk and practice asceticism
Seems like there is something obvious I am not doing or perhaps a MK setting that's incorrect? At this point I am open to ideas before I try #4 or #5...
Colin you might consider 2 things. Route the power wire out the back underneath the PDB to get it even further away from the Navi stack. And move the TM1000 to the rear of the copter. Otherwise it looks like you have a clean setup.
What's the downside for doing #4, #5 first and then doing the rest?
Seriously, the only thing that I would contemplate, given the symptoms you first reported, would be to add Xbee Wifi so you can use MK Tool's Balance window to get some idea of where the MK Board's determine the center of gravity and yaw balance are.
The yaw balance could explain why the clockwise motors are working harder (that is #1, 3 and 5). I doubt it's a CoG issue as those three motors are obviously spaced out around the copter -- therefore the sneaking suspicion is that it's yaw related.
Hope this helps
Oh Boy! More stuff to buy and software to configure! I've started on #4...
I see QC sells this and have followed this issue. And see this thread but could not glean what to do with the data once I have it. What values would I change in MK Tools to compensate the tendency for the kopter to want to yaw?
QC's product are indeed the Xbee Wifi I was suggesting.
The reason I'm suggesting you start there is just to try and diagnose what the actual problem is.
The yaw stability is controlled somewhat by the contribution made by the Compass Effect on the MKTOOL Misc window.
Can you also confirm what the Yaw P and Yaw I values are on the Gyro window in MK Tool. The defaults are 100 and 120 respectively.
Here are snapshots of my Misc and Gyro tabs.
I did a flight again today after I:
Braided motor wires on all booms
Twist and tide all leads including the BL leads
Moved the power leads from btw boom 2 & 3 to 3 & 4
Moved the TM100 from btw 1 & 2 to 2 & 3
Moved TX satellite to btw 4 & 5
Here's the result of that flight:
Flight time: 4:10:32 PM - 4:19:16 PM (524 secs, 00:08:44)Total: 522 secs, 00:08:42Elevation(GPS) : 0 3.48 5.896 mAltitude(Barom.): -1.1 3.95 7.2 mVertical speed : -1.46 -0.02 1.31 m/sMax speed : 12.1 km/hMax target dist.: 6.9 mSats: 10 11 12 (min/avg/max)Voltage: min. 14.8, max. 16.2 VCurrent: 0.5 21 32.7 AWattage: 8 331 500.31 WCapacity: 3116 mAhMotor1: 1.0 3.9 7.3 A Temp: 14 36 45 °CMotor2: 0.0 1.8 3.2 A Temp: 12 35 45 °CMotor3: 1.1 4.8 8.0 A Temp: 14 40 47 °CMotor4: 0.9 2.8 4.9 A Temp: 14 37 46 °CMotor5: 1.3 4.0 6.7 A Temp: 16 39 51 °CMotor6: 0.8 2.3 4.7 A Temp: 16 30 38 °CMagnet Field: 102 102 106 % (ok)Magnet Inclination: 56 59 68 degErrors / warnings:FC-Flag "LowBat" (5) occured 1 times!
It was bit windier than other filighs, but as you can see there is no change. The odd motors are stilling pulling more current. I have no idea why the "LowBat" waring came on. It was toward the end of the flight. On that log line Voltage 14.8, Current 20.6, Capacity 3103. Not much different than all of the :30 sec before it.
I got the Xbee to work so hopefully someone can guide me on what to look for in flight and how to correct for errors (?).
Odd that those three motors would be doing that.
Using MKTool, click on Flight Control, then the 3D button and you'll see the Balance window open up. The dot in the balance window should be at the center or close to it. Yaw scale running across the top should be pretty much at zero.
You do this while the copter is flying, of course, so some folks set up a camcorder to record the PC screen rather than fly and watch the screen.
The documentation for this feature, such as it is, is at http://www.mkmanual.com/mikrokopter-tool -- scroll down for the heading "3D."
Hope this helps
Colin this may sound nuts but what about taking motor 1 and 2 off of the booms, swap them, and give it another flight? To eliminate the motors this might work. If the readings are still the same then I would suspect the PDB and the various BL's
One othe etching to check would be the manual setup setting for each of the BL's. This is done in MKTools. Maybe Andy chime in about where it is. It might be there is something in the settings that the BL's have fundamentally different settings.
I think the only changes you can make for the BL-Ctrl are to change the default current and temperature alarm thresholds and which way the motor spins.
But your idea of swapping motors is a good one, but I'd only change one motor at a time.
Thanks guys. Motor 2 and 5 are brand new (see above). Still I will replace motor 1 with the one I took off 5 because nothing was really wrong with it.
Colin were you seeing the same results with the original motor 5 with the high readout on motor 5? If you do then it probably isn't the motors since you replaced it already. Better to switch 1 and 2 so you aren't introducing another variable.
Yes. Same results.
I switched motors 1 and 2. Here are the results of a flight with no gimbal /no load and almost no wind:
Flight time: 11:57:05 AM - 12:05:10 PM (485 secs, 00:08:05) Total: 483 secs, 00:08:03 Elevation(GPS) : 0 0.1 6.271 m Altitude(Barom.): 0 12.67 14.75 m Vertical speed : -2.35 -0.06 1.4 m/s Max speed : 9.7 km/h Max target dist.: 7.4 mSats: 6 7 9 (min/avg/max)Voltage: min. 14.8, max. 16.3 V Current: 11.6 21 27.7 A Wattage: 175 332 415.65 W Capacity: 2884 mAhMotor1: 1.3 2.9 5.2 A Temp: 24 42 52 °C Motor2: 0.9 2.0 3.4 A Temp: 22 44 52 °C Motor3: 1.3 3.3 4.7 A Temp: 25 44 50 °C Motor4: 1.6 4.5 7.1 A Temp: 21 55 65 °C Motor5: 1.6 3.2 5.0 A Temp: 22 50 58 °C Motor6: 2.1 3.7 6.7 A Temp: 22 45 53 °CMagnet Field: 101 101 104 % (ok) Magnet Inclination: 57 59 63 degNo errors found
What do you make of it? Why are motors 4 and 6 now pulling more current? Why is 2 still low? What do you recommend?
Not quite sure what to make of it. My hunch is that it is an aerodynamic problem as the problem didn't exactly move with the motor.
If it were my copter, I'd be hooking up MK Tool with a Xbee Wifi setup so I could bring up the Balance/Yaw window of MK Tool while the copter was flying so I could videorecord the MK Tool screen and see how the balance/yaw was being determined by the MK Boards.
Then I would use MK_GPXTOOL to play back the GPX file from the test file superimposed on the video of the MK Tool Balance/Yaw screen to see what was going on .
That might get us one step closer to diagnosing this.
I agree with Andy, those would be the next steps.