Hey guys, I have some issues with my H frame copter (1200x800mm). The copter puts its nose down in an attempt to take off, but if you manage to take off, it gets tilted and crashed. It is definitely not a balancing problem, I’ve rotated the controller and balanced everything out perfectly, it still doesn’t work.
The controller works perfectly fine on an X frame (450).
Do you think I should attach PID somehow according to the frame size?
Here I am attaching my log file. I wish you could help me.
https://drive.google.com/drive/folders/1324SG9EJow09snZoAQTuGWrNRiff8eH_?usp=sharing - link to the videos
00000099.BIN (906.0 KB)
Seen this a gazillion times. You need to reverse the Elevator channel in the radio.
Thank you for the answer.
Could you please go in depth of it?
How do I reverse it?
And why does it work well with the same setup on 450 with X frame?
And what do you mean by reversing the elevator?
If I apply the full throttle the copter will fly, but it will be swinging back and forth and then crash.
Because an H frame and an X frame are different. Comparing the two is useless.
What I mean by reversing Elevator is to go into the radio setup for this aircraft and change the output for the channel you are using for Elevator (pitch). Then you need to calibrate the radio in Mission Planner.
Hi, looking at your params shows way too high values for the the size of your vehicle:
Try setting it to the following and I believe it shall resolve your takeoff issue or very close to it:
ATC_ACCEL_Y_MAX = 7000
ATC_ACCEL_R_MAX = 45000
ATC_ACCEL_P_MAX = 45000
ATC_ANG_RLL_P = 7
ATC_ANG_PIT_P = 7
ATC_ANG_YAW_P = 4
After that test and than I suggest following the instructions here with new Autotune.
I did it as you said and it still didn’t work. Please correct me if i did anything wrong
Thanks a lot for your help and for the link. Unfortunatelly, I still can’t take off without risking a crash, it still tilts.
Well, if you re-calibrated the radio in Mission Planner and you are still seeing this issue, then I suspect there is an issue with how you have the aircraft configured that ArduCopter does not know how to deal with and this brings up a question.
When I looked that the log you posted I noticed the motor outputs are not on C1 through C4. The are on C9 through C12. Why is that?
I also noticed that the logged outputs are all different when ideally they should all be the same. This is telling me that either the air-frame is not balanced around its center of mass/gravity, the motors are not perpendicular to the air-frame, or a combination of the two.
On a Cube Black, or any other FC with an IOMCU, this is required to run Dshot which he is configured for.
But to that point perhaps Dshot600 is not a wise choice here. Set it to Dshot150.
Checking you video… Which way is Front?
Reversing the pitch got nothing to do with the copter tilting forward on takeoff since you don’t use pitch on takeoff. Your pid settings are not right for such a big frame ATC_ACCEL… params are way too high. To get to a reasonable starting point where your copter takes off would be a bit of a trial and error on the values of ATC_ANG_PIT_P and ATC_ANG_PIT_R because of the aggressive H shape of your copter.
Yes, I re-calibrated the radio, in MP and the copter before testing. The engines are connected to S1-S4 outputs, using DSHOT 600 with CUBE 2 flight controller. The engines are perpendicular and the frame is balanced perfectly, I checked it several times. The difference might be there due to parameters that i change a lot.
Re-balancing the copter doesn’t solve the issue, I added a detail that weighs 150 grams to the back and it doesn’t help.
Thank you,I will try that. What are the restrictions that make it better on DSHOT 150 in that case?
The front is on the right.
I have no idea what to do at that point, I amjust trying whatever. I just readjusted the params according to the link you gave.
Here is the link to the parameter file:
There may be problems with larger motors and Dshot600. Even with smaller motors I have seen some stuttering at the higher Dshot rates. And in any case there is zero advantage to running a high Dshot rate on this craft. You could run PWM and not see any difference in performance.
The wire from flight controller to ESC is very long in my case. PWM signals wouldn’t work any better in that case due to the interference from the wires. Therefore, digital signal would be better than analog one. In earlier versions of the model I used PWM, but when i switched to DSHOT it got noticeably better.
As well, I removed the plugs and soldered the wires straight to ESC,so that there is less interference for the signal. those wires are like 5 cm.
OK. Try Dshot150 but perhaps there is something else fundamentally wrong. If you do get this off the ground with a burst of throttle does it fly at all?