Hi everyone!
We have customized hexa+ and we seem to be having a problem with it pulling forward automatically when throttle is applied. I understand that the PID setting are crucial when using a customized hexacopter. Here are the specs of our rig:
The controller /stabilizer is a Sparkfun APM 1, assembled by UDrones.
40 amp ESCs, from Innovative Designs.
30 amp Scorpion series II motors from Innovative.
Camera gimbal, interchangeable to 3 lbs., with gyro stabilization.
13,5000 mah 14.8V lipo battery
The length from motor to motor is 840mm
The props are 10x7 Tri-Blades from Masterscrew
All up weight with a GoPro Hero II: 9.57 lbs.
All the motors have been tested to be within 50kv of each other
I have adjusted the P setting for large motors, but I'm still confused a bit about I and D, and maybe they are making the Hexa go forward? Leveling of the gyro has been checked and double checked, and it still wants to fly forward.
When doing the hand test, it seems to really only pull forward when you give it ample throttle to get off the ground (just enough to crash)
Here's some pictures of the rig, let me know what you guys think...
Replies
We're still struggling with this rig. We've put a brand new APM 2.5 board in it, thinking it was a gyro or accelerometer or chip problem. The firmware has been reloaded/reset 20 times, brand new manually calibrated ESCs... The data from mission planner seems to suggest the board is putting out incorrect PWM to the ESCs...
Can someone please help? I've attached the data log for the last two "attempts"... It just keeps pulling to the forward right no matter what with just straight throttle applied...
2012-10-25 13-07-56.tlog
Im new to this, BUT,
have you calibrated all esc´s the same? have you checked that there isnt a bad motor somewhere on the front ?
i had this problem and it was a motor that appeared to work but was drawing more current than the others and thus not spinning as fast at the same throttle level,
PID tuning is to control the change of attitude, to get it following your stick or autopilot inputs quickly and smoothly without too much oscillation.
if its consistently pulling forward in stabilize, then its because it thinks its not level. if the level is good enough to fly with then the in flight level (with no wind) will give you the best results. if not, then level it on the ground first, it looks new so your landing gear is probably still square, but the important thing is to level the motors. i do it with a spirit level between prop spinners, then invoke level either through mission planner steup (if using a usb cable make sure the cable isnt pulling APM off its resting position) or with the radio holding disarm for ~10 seconds.
james
Check motor axle lengths from the CG/center. Check motor mount tilting/bent.
On the software side, minor roll/pitch on take off is usually a leveling issue. If you auto-leveled, then your APM is way out of physical tolerance--physically level the board and run the level command (don't auto-level).
Also, not liking your GPS mount position. Get it up and away from the Rx.
And... are those Aircraft Spruce AL booms? I just got them for my Y6 repair and they are very nice pieces (and 6037 AL).
We have used a tachometer to read all the engines while running and when enough throttle is applied for the unit to lift we're getting ~43k RPM on the front 3 Motors, and ~55k on the rear 3 motors...
Is this a firmware problem? PID? Any help would be appreciated =)