Yaw dont works!

PX4 Autopilot Flight Controllers đź’»
1

Hello everyone,

I’m working with a hexa airframe and the stabilize mode is works well (pitch and roll), but the equipment is rotating around its own axis on the fly.

Even if i do a yaw command, nothing happens, it only destabilizes the flight.

Has anyone had the same problem?

I’m using the pixwalk1 and EDF motors.

2

Hi @alcomen,
Do you have a log of the flight and maybe a picture of the drone? Are the rotors maybe not well aligned?

3

Hi @bresch,

Sorry for my absence, I was hospitalized with health problems. I’m back and fine, I’m returning to the project.

Attached to the picture of drone.

I checked the motors alignment and apparently everything is ok.

IMG-20211116-WA0037~2
IMG-20211116-WA0037~21233Ă—717 194 KB

4

Hi @alcomen sorry to hear that, I’m glad you’re fine now!

Two things that come in my mind when I see that picture:

  1. do you have 2 CW and 2 CCW EDFs?
  2. most EDFs have static blades after the rotor to cancel out the torque; did you remove/modify them?

DeepinScreenshot_select-area_20220106143620
DeepinScreenshot_select-area_202201061436201160Ă—711 283 KB

Good luck!

5

Hi @bresch

Thanks very much!

  1. yes, a have 2 CW and 2 CCW EDFs;
  2. I don’t have experience with EDF. All my projects before this one were with propellers. I didn’t know about that “anti-torque” detail. I haven’t modified it.

maybe I have to manufacture another metallic part to replace this one with “anti-torque” or think of some device to control the air flow.

thanks for the info, would hardly find about this effect in these EDFs so fast.

6

Yes, you’ll see that an EDF is designed to produce no torque at its nominal RPM.

However, the good news is that you don’t need that torque to produce yaw control, you can also slightly tilt (3-5 degrees should be enough) the EDFs to produce this yaw torque. For example,on a quad x multirotor, the front right motor is turning CCW, so it’s supposed to produce a CW torque. Now If you tilt it to the rear-right, its thrust will produce a CW torque.

So just tilt them and you won’t need to modify the stator of the EDFs

1 Like
7

Hi,
It’s a good idea, I’ll do it and test.
I’m a little worried about the weight of the drone and how much torque I’m going to get, these motors apparently seem small.
I changed this setup from Quad to Hexa (+) due to the low thrust for the weight of drone, now the thrust is ok, this yaw control issue remains to be resolved.

My setup:
EDFs: EDF Ducted Fan JP Hobby 120mm + motor 18s 510Kv
Aircraft weight: ~20Kg/44lbs.

I’ll be back with the results as soon.

Thanks

8

Hi @bresch
I tilted the motors and now the yaw control works very well.
Thank you for all information!
Best regards,
alcomen

1 Like