Servers by jDrones

Arduplane - tilt-quadplanes with all four motors tilting


(arnaud) #1

Hi everyone,

I am sorry if this might be a basic question but I am exploring Arduplane to use to control a VTOL fixed wing aircraft that has 4 motors that all tilt at once thanks to a servo.

Reading through Ardupilot website I see that part of the tilt-rotor configurations supported are:

tilt-quadplanes with all four motors tilting

So I presume this should cover my needs?
What I am interested in is to be able to use the very same motors in vertical and horizontal flight (no surfaces) to control all rotations (yaw, roll pitch). In particular, I also would like the autopilot to automatically switch roll to yaw once level so it can be flown intuitively with the RC.

Assuming it does suit my needs, I have a slight issue that someone may be able to help with:
I followed the best I could the set-up instructions on the website and when I got to assigning my servo to tilt and tried to test the servo, I couldn’t get it to work (my understanding is that he servo should change position when going from Qstabilise to Manual?)

Would anyone be kind enough to a) confirm that as it stands Arduplane is indeed able to do what I am trying to do, b) clarify how to assign a servo and then how to test it?

Many thanks,
Arnaud


(Greg Covey) #2

Hi Arnaud,

Yes, I agree this should work for you.

I believe you will want the Q_TILT_TYPE parameter set to Vectored for this feature.

Make sure the Safety button has been pressed to arm the servos and that you have properly powered the Main/Aux outputs with a separate 5v BEC.

The APM v3.8 servo output control is super flexible! I would follow the APM Wiki setup here and use the example in the “Tilt Servos” section. You assign what servos you want to use by setting the appropriate SERVOn_FUNCTION on the servo n of your choice.

The setups may be limited to a tricopter layout so you may need to tie the rear two motor tilts together. It may also be that the Wiki isn’t complete in this area so hopefully @tridge will see your post here or in the tiltrotor thread.

Good luck!


(arnaud) #3

Hi Greg,

Thanks for getting back to me, much appreciated.

I have made some progress with the servo and it now works well to tilt. It is great to have the parameters to set speed and range of tilt, as well as reverse direction, very convenient. In VTOL it seems indeed that my motors are behaving like a quad but as soon as I switch from Qstablise to Manual (which causes the servo to tilt) my motors seem to all spin evenly and only be controlled by the throttle. I hold my plane without props and when I effect a transition and then move the aircraft about, the motor speed remains constant and the ardupilot does not seem to try to control pitch/roll/yaw with the motors. I don’t know if I was clear in my previous post but I have NO control surfaces (no elevator, aileron or rudder) I just want to do everything with the motors.

@tridge, if you see this can you help?

Cheers,
Arnaud


(arnaud) #4

Hi everyone, I have been playing around with Quadplane and I have come to the conclusion that in its present form it won’t do what I want it to do, which is for memory to control a quadcopter with fixed wings using ONLY the 4 motors in both vertical and level flight.

I have managed to achieve this using Copter by tilting the Pixhawk at the same as I tilt the motors (using one servo). It works but the problem I have is that as soon as I transition roll and yaw become inverted and so it is difficult to fly.

Is there a way to switch the yaw and roll channel at the flick of a switch on the remote, or better still based on the position of my servo?

Thanks for your help,
Arnaud


(arnaud) #5

Hi guys,

I still haven’t resolved this problem, so I am once again reaching out for help.

I am developing a concept of electric VTOL aircraft with fixed wings, it is very similar to Airbus Vahana, with 2 staggered wings and 4 props per wing. I have a Pixhawk 2 in an experimental plane I am developing and I would like to adapt the SW to something more specific to my concept. Unfortunately, none of the VTOL options in Ardupilot/PX4 fit my concept.

I am using the copter firmware (Ardupilot build, mainly because of the Landing gear function) to fly the aircraft. My aircraft is controlled like a quad in vertical flight (I have 8 props for redundancy and have duplicated outputs to 4 groups of 2 props). I rotate my wings using a servo linked to the landing gear function (that way during landing the aircraft transition back to vertical automatically as the landing gear deploys). My aircraft transition from vertical to horizontal flight pretty well but once transitioned I want to control the aircraft with only thrust, I have NO control surfaces at all.

It works OK so far but there are 2 problems:

Problem #1, yaw and roll are inverted in horizontal flight compared with vertical flight, which makes it a little difficult to control by the pilot and I suspect difficult to stabilize by the autopilot too (as the autopilot does not “know” that yaw and roll are inverted).

Problem #2, I don’t believe the autopilot can control the aircraft in horizontal flight and RTL or follow a mission because the autopilot does not “know” that my props are now applying forward thrust (rather than upward thrust).

I noticed that there are a number of VTOL options in both Ardupilot and PX4 builds but none of them attempt to control the aircraft using only CCW and CW props in both vertical and horizontal flight.

Would anyone be able to help me create a new configuration that matches my airplane so that it can be flown safely with my Autopilot in both vertical and horizontal configurations using only my props? (What is mean by safely is both in manual flight and in automatic flight, being as part of an automated mission or following the trigger of a failsafe).

I hope someone will be able to help,

Many thanks,
Arnaud