Tiltrotor support for plane

Servus Jeff,

you need also a tilt servo for the rear motor to control yaw in hover. .

I’m working on changes to avoid the need for that, so we control yaw in hover by differential tilt of the front motors. That is needed for the eflite convergence, but also makes sense for any tilt-tri-quadplane as it saves you a servo output and makes the rear motor mount simpler.
The only real downside is you need to be able to go past vertical on the tilt of the motors, or you will tend to drift forward in hover.
Cheers, Tridge

Tridge,

Can Arducopter be configured for a reverse Y6 such as two motors on the front of the aircraft and the other four to the rear. If so, how would that be configured? Thanks for all your effort!

Tim.

I was hoping you were going to say that! That would be great!
Can you also have a look at my previous post further above addressed to you regarding setup and keeping the rear hover motor continuously on whilst tilting the other two forwards? Thx.

Regards
Sam

@Tridge
Clockwise from which point of view ? The pictures of copter-wiki suggests from above. If cw/ccw means cw/ccw seen from above we have this situation:


Increasing power on front right motor leads to roll-feedback in direction of the red arrow - the wrong way round ? In this case we have to change the front motor direction

Regards Rolf

you’re right, when viewed from above the right motor should be CCW, and left motor CW. I had it backwards!

1 Like

I added support for vectored yaw in tilt quadplanes today, and tested it on an EFlite Convergence.


It should allow any of the current tilt tricopters to be setup without having to have tilt on the rear motor.
The PR is here:
3 Likes

@tridge: Super, and congratulations.

We will probably design a new tilt mechanism for vectored yaw… So we can fly without the rear tiltservo.
.
Today we was happy with your improvements of the forwardtransition: Perfect- thanks a lot

Logfile: https://www.magentacloud.de/share/06cip1ly1r

Regards Rolf.

That is fantastically awesome! Thanks Tridge! :slight_smile:

Three questions:

  1. Roughly how much rearwards tilt angle do you need from vertical on the tiltrotors for effective yaw control? From the video yaw control authority looks really good.
  2. Is it possible to fly in reverse in hover?
  3. If I have a tiltrotor tricopter without any wings; how do I make the rear hover motor remain on throughout the flight, even in forward flight, and is there currently a way to limit the tilt motor forward angle, so it produces a minimum in hover lift?

(Note our intention is to have wings eventually, but we’d like to configure the copter etc first and experiment how much wing is required to maintain forward cruise winged flight)

Some recorded log data (Dashware)

Rolf

2 Likes

It’s about 10 degrees on my convergence.

yes

I don’t know if this will work at all, but you could try setting the SERVOn_MIN/MAX values to prevent the motors moving all the way forward, and then set Q_TILT_MAX=90 and set Q_ASSIST_SPEED=100.
I haven’t tried it though.

really nice! I hadn’t heard of DashWare till now. Nice system!

A quick note on how to configure tilt-quadplanes with vectored yaw.
The two key parameters are:

  • Q_TILT_TYPE=2

  • Q_TILT_YAW_ANGLE=10
    The Q_TILT_TYPE=2 means that you have a tilt rotor that uses motor tilt for yaw (ie. vectored yaw).
    The Q_TILT_YAW_ANGLE is the angle in degrees that the tilt motors are tilted back when at their full up value (as set with SERVOn_MIN or SERVO_n_MAX if the servo is reversed).
    For my convergence I set Q_TILT_YAW_ANGLE=10 as the motors tilt back about 10 degrees when fully up. This parameter allows the code to work out what PWM value to use for the motors to be straight up, and also to work out what range of movement to use in controlling yaw when hovering.
    The only other unique setup for this type of vehicle is you need to tell ArduPilot which servo output controls tilt of the left motor, and which controls tilt of the right motor. The SERVOn_FUNCTION for left motor tilt is 75 and for right motor tilt it is 76.
    So I have:

  • SERVO3_FUNCTION 75

  • SERVO3_MAX 2050

  • SERVO3_MIN 1000

  • SERVO3_REVERSED 0

and

  • SERVO4_FUNCTION 76
  • SERVO4_MAX 2000
  • SERVO4_MIN 950
  • SERVO4_REVERSED 1

that sets up the aircraft so that servo output 3 is the left motor tilt, and servo output 4 is the right motor tilt. The MIN/MAX values and have been adjusted to point the motors straight forward in manual, and so they are centred on being straight up in QSTABILIZE mode. Notice that for the convergence the right motor tilt is reversed (which is why SERVO4_REVERSED is 1).

1 Like

@tridge

Marvellous ! SERVO3_TRIM and SERVO4_TRIM value 1500 may remain ?

yes, when used for tilt of this type of vehicle the motor tilts are treated as range values, not angle values, so the trim is unused.

Another note on the EFlite Convergence. The wires going into the ESCs can be very confusing. It uses reasonably thick 3 wire cables, which correspond to power, ground and signal (signal as PWM). The colours are very confusing though, and there is a hidden connector inside the wing cavity which on my plane swapped colours. So white went in on the fuselage side, but it emerged as black at the ESC. It is really baffling when setting it up until you pull out the wire and see there is the hidden connector inside the wing cavity which swaps the colours.
Make sure you trace the connections carefully with a multimeter.
When we discovered this we wondered if the people in the factory were just trying to confuse DIY people :slight_smile:

Hi Tridge,

Could vector control of the front motors be used not only for yaw but also for forward flight ? This could reduce battery consumption:

It costs a lot of power to fight nose down against the wind due to downforce on the wings. Here is an example, as at 15 kph headwind the climbing ability decreased to zero and current inreased significantly. I then let the VTOL drift backwards with the wind and was thus able to win a safe height for forwardtransition.

Especially at the end of the flight with an almost empty battery vector control could save time (and batterycapacity) while exact reaching the desired landingpoint in windy conditions. We ask from expirience at the end of today’s flight (Backtransition at 09:05)

Regards Rolf

1 Like

yes, that’s a good idea. It could be linked to Q_VFWD_GAIN. The question is really what angle limit to apply to retain stability. Maybe just Q_TILT_MAX ?
I can try it on the convergence and see how it goes.
Thanks for the suggestion!

It turned out to be one line to implement it:


I’ll try it on the convergence on the weekend. Works fine in the simulator.

1 Like

What modes will this work in? In Quadplane we only get to enjoy the benefits of Q_VFWD_GAIN while in QLOITER mode. I have a Github request for that to be expanded to QHOVER.
With this tilt rotor, will the motors tilt forward in QHOVER, or is it limited to QLOITER also?