I have been working on a quadplane project for the past few months with mixed results.  This airframe is a 3 meter wing span custom design flying wing weighing between 12-15kg.  I started off with a quad setup for the VTOL capabilities.  I had some very unfortunate problems with the quad motors and ESCs though which led me to the decision of an X8 configuration.  I loaded the latest Copter X8 firmware and started testing without the wings attached... all was well and I was able to tune the setup well and had good results.  I then loaded the latest Plane firmware, leaving Q_Enable at 0 I bench tested the plane equipment and all seemed well.  Then, I set Q_Enable to 1 and copied over the X8 PID settings.  Once changing the Frame configuration to Octaquad (3) all kinds of things were screwed up... The plane motor esc was no longer receiving a PWM signal and the control surface servos were acting very strange, humming and moving on their own regardless of flight mode.  The octa motors did however work normally.  I tried plane firmware from 3.5 all the way to the latest 3.7 with the same results.  I just loaded the beta 3.8 rc5 and this problem went away.  All systems work properly.  However, the motor mapping on the octaquad configuration is not right.

I setup with octaquad motors as suggested in the wiki:

Ch5 = motor 1  

Ch6 = motor 2

Ch7 = motor 3

Ch8 = motor 4

Ch9 = motor 5

Ch10 = motor 6

Ch11 = motor 7

Ch12 = motor 8

I have the ESC labeled by location, not # to make things easier. 

Ch5 - motor 1 = Front Right Top

Ch6 - motor 2 = Front Left Top

Ch7 - motor 3 = Rear Left Top

Ch8 - motor 4 = Rear Right Top

Ch9 - motor 5 = Front Left Bottom

Ch10 - motor 6 = Front Right Bottom

Ch11 - motor 7 = Rear Right Bottom

Ch12 - motor 8 = Rear Left Bottom 

When I use the motor test menu, these are my results:

A spins motor A 

B spins motor E

C spins motor F

D spins motor C

E spins motor G

F spins motor B

G spins motor D

H spins motor H 

I was able to switch inputs around until A=A, B=B and so on but the mapping is still messed up in the firmware.  Control inputs don't match motor outputs. 

I checked the RC outputs to verify their channel mapping and they seem accurate: 

Rc5 =33

Rc6=34

Rc7=35

Rc8=36

Rc9=37

Rc10=38

Rc11=39

Rc12=40 

Does anybody have experience with this, or any suggestions on how to fix this? 

Thanks,

Chris 

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I just found some more information over on arudpilot and it seems that a couple people are having the same or similar problems.  

http://discuss.ardupilot.org/t/quadplane-octaquad-servo-buzzing/111...

Any resolution to this? 

After some creative motor mapping, I was able to have all channels working properly.. or so I thought. 

I bench tested and everything seemed fine but its hard to tell while the aircraft is secured down.  I took it outside and attempted  a hover in QStabilize.  Throttle, roll and pitch seemed fine but Yaw was not.  I added a touch of right rudder and the plane yawed to the left and tried to flip over the nose.  Not sure what this means other than there must be a mapping/control output issue.   

If anyone is curious or has some suggestions, please advise. 

Here is my param file. 

Parameters 

Attachments:

FIXED!

I uploaded the latest beta firmware 3.8 rc6, then figured out that the Frame Type number is off by 1.

Frame Type:
0 = Quad
1 = Hex
2 = Octa
3 = Octaquad
4 = Y6

The actual correct type identifier for Octaquad is #4. Once I selected this, everything worked fine and I was able to complete two successful hover tests.

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