my 3DRobotics Arducopter with APM crashed yesterday. Nothing broke at first sight (two props died) but now it's doing strange things. When I try to lift off it leans stangely to one side. I can get it in the air but it floats around like crazy. When I start the motors, at about 5% throttle one CCW motor spins, a little later the other CCW. At about 8 % throttle the other two CW motors start spinning. (see the youtube video!) Whats wrong? Soldering maybe?! I did ESC calibration - still the same. :( One motor does vibrate but this should not be the reason for the motors to not start together.
I postet a video on youtube so you can see what the effect is:
I am sure that your issue is with vibration. The vibes are causing the IMU to think it's tilted. Either try to straighten that motor shaft or replace it and you should be good. If the shaft is good, are you trying to run crashed props? Either way, eliminate the vibes and you should be good.
You may need to recalibrate your ESCs after a bad crash. I've had them loose calibration like that many times.
Also check for increased vibration due to bent motor shafts, prop adaptors.
Also, make sure you have soldered the low pas filter pads on the IMU as per instructions in the wiki.
Connect it to the APM Planner and check if the sensors are responding ok. This seems a hardware problem, it happens to me a lot of times after a hard crash: a gyro looses contact to the board and then AC gets crazy. Then I have to reflow the board with a heat gun and an infrared thermometer to control the temperature limit.
Thanks for the quick response,
I removed the props, and balanced the motors. Now there is hardly any vibration in the system. (I did fly before with really bad props and vibration, but I never had problems.)
Anyway - What else I did until now:
1.calibrated ESCs (I hope I did?! - Full throttle up (Ch3), power on, beep-beep, Di-da-di-da-di, throttle down, disconnect)
2. flashed new firmware.
3. checked sensor response in APM Planner. I can see the data produced by the sensors, but if what I see is cool?! I don't know. Looks alright. (what is a healthy gyro datastream?)
4. with no props I checked the copter response in STABILIZE mode. I reacts strange...e.g. when I tilt it around 45 degrees, one Motor does even stop. :(
what I will do: Check all my Soldering (oh F**K!)
Thank you very much, guys! I'm really desperate.
To check if the gyros are ok you can watch the artificial horizon on the APM Planner, if it reacts according to the board movements then gyros are ok.
The compass drift is normal, it starts pointing to the north and then it moves to the correct heading. The motors usually stop when you tilt the copter at low throttle, so the behaviour you've commented is not normal. Have you calibrated your radio?
Can you attach a flight log? For example the one recorded in the youtube video. Have you tweaked the default PID's?
" Have you tweaked the default PID's? "
Good call. Take a look, jjohow, and make sure you don't have a decimal in the wrong place or something on any of your PID parameters.
Also check the soldering on the actual motors. I had an issue (after a crash) where there was a dry joint on the one motor wire and had a similarish problem.
Although watching the video, it looks like hardware problem to me. If it was software, re-loading the firmware should of sorted out the problem...