I finished my build last weekend.
-TBS style frame
-APM 2.6
-Sunnysky V2216-12 800KV motors
-Hobby King 30A Blue ESC (f-30)
-GPS-6M+HMC5883L Compass module
-3s 5000 mah 20c LiPo Zippy
-3DR Power Module
-Hobby King Orange receiver and Futaba T8FG Super transmitter
The issue I am having is that immediately upon take off the quad spins out of control.
The steps I have taken so far include:
- Ensuring motors are securely fastened, prop installation and prop directions are correct
- Re-installing the firmware on my APM 2.6 (many times)
- Re-installing the firmware using X style frame type (where I was using the "Spider" style frame before)
- Resetting the APM in the CLI and re-installing the firmware
- Calibrating the ESCs together
- Ran the Test>Motors in the CLI to ensure that I have the motors hooked up properly
- Ran the Test>Compass in the CLI to ensure working compass as well as the GPS
- Adjusting the trim via my Transmitter (I can get it to spin the opposite direction but doesn't settle out)
- Using the "Save Trim" setting in the Extended Tuning menu to try to trim out the spinning (same outcome I can over correct, but not correct the issue)
Today a friend gave me a tachometer and I noticed that at 50% throttle both of my counterclockwise motors seem to spin at about 1.5-2k rpm faster than the two clockwise motors. I ran this test about 3 times with the same results.
I also ran the ESC calibration and noticed that when I am at the part of the ESC calibration where the motors power on all of them seem to run at the same RPM at about 30% and 50% throttle.
This leads me to believe that there may be an issue with my APM 2.6. I was wondering if anyone had any ideas on this. I am new to builds, have about a years worth of experience flying a RTF quad, don't rule boneheaded mistakes out :)
Thanks much!
Jason
Replies
Tried to tune PID settings.
I tuned it following the Dave C method : http://diydrones.com/forum/topics/arducopter-tuning-guide
P and D values were really low compared to similar spider style builds like this one: http://www.diydrones.com/profiles/blogs/tbs-disco-first-flight-report
For P I got 0.0020
For D I got 0.0005
I tried it several times and rested on those numbers. Any higher and I would get strong oscillations.
I am not entirely sure what I may have changed but the spinning is pretty much under control now. What I did was essentially take apart everything and rebuilt it.
Now it's not spinning like a top, but instead the spin is correctable with a tap of the yaw/rudder in the opposite direction, However when i do this the quad just keeps moving the in that direction. Same goes for any pitch or tilt maneuvers, the quad starts to keep going in those directions - a good adjective would be "sailing". Any clue as what this might be indicative of?
Since the rebuild I have:
I was told to try to see if there is a way to adjust the gimbal gain I might take a look at that when I get home.
Wondering if anyone had suggestions.
Thanks!
Jason
When you correct the yaw, what do you mean it moves away ? Your yaw correction should at worst make it spin in the opposite direction. The yaw control has no effect on movement up/down, left/right or forwards/backwards.
Your corrections against the original drift seem to be just that. It might be moving say away and you counter that with a move towards thats a bit too much, so it comes towards more.
if the drift is not too much have you tried loiter mode to see if holds still ?
When I correct for the any motion including yaw it will continue to move in the opposite direction of the original movement. It usually yaws, right, rolls right and pitches forward a little on take off so I have to try to correct for all three movements right off the bat.
I really have to work hard with the transmitter to get it to stay in a relatively small area, which isn't right to me.
Centering the sticks does make the copter frame come level with the ground and stay at a fixed height, but it will continue to move sideways, either backward/forward and yaw in whatever direction it was last going and carry whatever speed it was moving at.
To me centering the sticks should make the copter level out and stay in a relatively fixed position when in stabilize mode.
I will try to get a video up. I will also give loiter a try.
Thanks for the help so far, I really appreciate it.
I meant to say gyro gain in the above post. At any rate didn't do it because I couldn't find a way to do it haha.
Compassmot = 6% (checked that today)
Going to try tuning the PIDs next. I read that it helped some other folks stabilize their birds. I will post what I find.
If both CCW motors are trying to spin it sounds like the APM is trying to yaw itself for some unknown reason.
Sounds like a radio calibration with no trims might help. It might turn out your yaw might be slightly off center forcing the APM to want to yaw to do what your radio is telling it to do.
You really shouldnt be using tx trim at all. Adjustments should be done to the APM config using something like MP.
Thanks! I checked around the settings on my transmitter for any remaining trim adjustments I had made previously. I didn't find any in the 'sub trim' menu or on the main screen. I re-calibrated the radio via Mission Planner - if the values work like i think they do: for the yaw i get a min of 1100 and a max of 1942, right in the middle of those values is 1521 and that's where it's resting (it jumps between 1521 and 1522 a little), but that should effectively be 0 yaw - that makes sense to me not sure if it's right.
I'll have to try it in the morning. If that doesn't help I might make another profile on my transmitter to make sure that I'm starting with clean settings.
I'll post my findings. Thanks for the tip about not using the transmitter to trim out the quad. It makes sense.
J
Might be my imagination but It seems like it helped a little. Still spins clockwise on take off though.
Not sure on what to try next other than replacing the computer. I bought parts to replace motors and escs because i thought that was the original problem, but seeing that the two cc props and the two ccw props are spinning with the same RPM this makes me think the motors/escs are fine.
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