Servers by jDrones

SingleCopter & CoaxCopter Support

(Francisco Ferreira) #151

Wow that’s old. I’m not even sure there was Single and Coax support in that version. You will only find the FRAME_CLASS parameter from version 3.5 forward, it didn’t exist before (because all vehicles were separate firmwares but are now merged).

(Martin Snaith) #152

Hello Leonard

Thanks to you and all the others who enabled arducopter to control a Coaxial frame. After a couple of years using quadcopters as research platforms I’m now working on an underwater coax frame. This has coaxially mounted props on channels 5 and 6 and gimbal servos on channels 1 and 2.
After a bit of esc tuning we can get some x y z control with a joystick which is great.
But I notice that the gimbal (x y) control is linked to the throttle. So on the bench all looks good. In the water we need high throttle to control the gimble.
Could you or one of the developers point me at the likely parameters or pwm driver code to tune this relationship?

Thanks again for your work. I’ve attached a photo of the prototype and will post a tank test video as soon as possible.

Kind regards


(Colorfuljune) #153

HI, How to solve this problem?

(Andrew) #154

Hello Leonard,
I’m absolutely new to autopilots and software they run so I hope for some advise. I hope I’m directing my question to the right person.
I’m building a small single copter. I’m about to buy the Pixhawk Mini because the PX4 is quite large for this drone. Would appreciate it if you could confirm for me whether the Mini is fully compatible with the PX4. Will Ardupilot/Arducopter run properly on Pixhawk Mini in the single copter mode?
If not, what hardware-software combination would you recommend?

One more question: if Mini is acceptable - can I mount it vertically instead of horizontally?

Thanks a million!

(Sergio Postigo Huanqui) #155

Hi there! I´m a little confused. Copter documentation says I shouldn´t connect Servos to MAIN ports. Nevertheless, the SingleCopter & CoaxCopter information says they should be connected to MAIN 1 to 4…
Can anyone clarify me this? Thanks!

(Leonard Hall) #156

The output frequency of the ports are defined in blocks of 4. So you should not put ESC’s and servos on the same block of 4 outputs.

I think that is the only issue…

(Leonard Hall) #157

Hi Andrew,

It should be fine. And you can rotate it with the AHRS_ORIENTATION parameter.

Just a warning. I have learnt more since I did the output mixer and I suspect we can do a better job than we have currently. I will hopefully get a chance to improve the controller soon for single and coax copters.

(Andrew) #158

Thank you very much Leonard!
Please keep me posted on any improvements you make for a single copter.


(Nam ) #159

Hi all, I’m building a singlecopter and was able to fly in stabilize mode. However, in Althold mode the barometer seems to be strongly affected by the prop’s airflow as it is located directly above the prop. I’ve already shielded the baro with dark foam but that doesn’t help. Is there any solution other than just re-locating the baro outside the prop’s airflow (which is not an option for me right now). Do you think if we tune the control gain carefully they will automatically compensate for that effect?

(Lester Wong) #160

Hi, do you mind sharing your coding? because currently i’m designing a singlecopter and hope to get your coding as reference.

Thanks in advance.

(Reyes De Jong) #161

Hi Lester,

The code that we used for our coaxcopter was the one in the ArduCopter v.3.2 Firmware (latest version available back on 2015), which was a beta version in 2015. We didn’t make any code modifications, just selected corresponding firmware on the Config.h file.

I had download links but they don’t work any more, and I don’t currently have the files of the project

Good luck!

(Lester Wong) #162

HI ReyesDeJong,

Thanks a lot for the information.

(Lester Wong) #163

Hi Nam,

Can i know you refer to which source code version to build your singlecopter?

Thanks in advance.

(MadD MacKx) #164

Its pretty cool to see this thread still alive and growing…I wish I had the time to pull my coax project back out and dust her off !!

Best of luck to everyone!!

(Mohajer ansab) #165

hi Droner

I have a problem about surface control of single copter when copter armed.
at first test when the vehicle is not arm roll and pitch surfaces control work fine but when copter armed roll and pitch surfaces doesn,t work properly and roll and pitch servos starts jitering motion or there is delay in roll and pitch command from radio control to surface control. I use pixhawk board for control of single copter according to

can you help me for this problem?

(CM) #166

Hi Mohajer,

If I recall correctly the jittering once armed is normal for the later versions of the code. The control surface deflection is calculated to be inversely proportional to the throttle level. In other words, if the throttle is low the surface deflection is greater. This is because at low throttle levels the surfaces have less airflow over them and require more deflection to produce the same forces (moment). The output to the surfaces is fluctuating slightly and that slight fluctuation is amplified by the near (or at) zero throttle level. To confirm this, try removing the propellor or disconnecting the ESC and increasing the throttle to see if the jittering on the controls reduces. Additionally, the surfaces may not respond normally when on the ground because your control outputs are being combined with the sensor data to try and hold a particular attitude. If possible try having someone hold the copter in the air and change the vehicle’s attitude manually. First leave the controls centered and move the vehicle around to make sure the vehicle is using the control surfaces to make corrections in the correct direction. Next have them follow your inputs to essentially trick the controller into thinking it is flying and make sure the control movements again match what you expect.

I am not sure how to fix the delay. It is something I do recall experiencing in bench testing, but I do not remember it effecting the test flights. If the problem is serious enough it may be worth messaging one of the experienced developers on here such as Leonard Hall or Mackay. If at all possible I recommend preforming some form of tethered test flight once you’re ready to see if the problem occurs in flight without risk to the vehicle.

(Mohajer ansab) #167

Hi droner
I send Picture of My vehicle in this letter. Is there any problem in my
center of mass or external shape single copter? we test my copter and hold
the copter in the air and change the vehicle’s attitude manually.
in our test First leave the controls centered and move the vehicle around
to make sure the vehicle is using the control surfaces to make corrections
in the correct direction and them automatically roll and pitch by change of
my vehicle attiude but control surfaces don,t follow my command roll or
pitch even in high throttle.
where is my problem?

my adittional pics are:

in this Adress I upload the film of my test : > Blockquote

(Mohajer ansab) #168

hi I am too for this problem

(Leonard Hall) #169


It looks like you have surounded your fins in the shrowd making it hard for the air to be deflected by the fins. You should probably lift the lower edge of your showd to let the air move forward and back, left and right, to control roll and pitch.

Your fins should not touch each other at maximum deflection of both fins.

It is hard to see what way things are moving and what angle you are holding the aircraft in your video but it looks like it is moving in the right direction but that your gains are too small.

The other thing that is probably confusing you is the I term is growing to maximum and dominating your output. If you set I_Max to a small number this will make the reactions clearer.

I hope this helps.

(Mohajer ansab) #170

Thanks you from your Attention to my question. I have several questions from your opinion :

  1. What do you mean by shrowd? Is there the same white chamber that the blades are located in? And
  2. That you said shrowd should raise its lower edge so that the roll and pitch control are carried out, i.e the white chamber requires for bases or should the lower edge of the blades be taller?
  3. Is there a need to change the size of the blades? In height or longitude direction?
  4. What do you mean by gains? control PID gains or word mean resault? which one of control PID gains should be raise?
  5. I will reduce I_Max parameter next a few days and will send it’s resault. What is the effect of the I_Max parameter on the operation of the copter intuitively and physically?

excuse me because of my Shortage ٍEnglish language
Thanks alot for your help