Servers by jDrones

Dual-motor tailsitters

( research air) #301

Hi, congrats! I find into the wind is most pridictable and controlable, and do transitions upwind
Tridge , I volenteered us for NASA Mars project, see last comment on mvi 0160

(tridge) #302

cool! That would be really fun. Thanks!

(lorbass) #303

I’m sorry, I have checked the safety procedure with 3 Controllers, each with Copter stable, Plane
stable, beta and latest. All systems could be switched to a stable Light on with nothing ready, just the controller
powered via USB. (Of course arming is then not possible)
The Pixracer PX4 V4 also but only with Plane stable and Beta of April 4.
But NOT with PX4 V4 latest.
The Light looks like:
And if everything ist OK (no error messages) arming via Throttle is possible and the mots are running.
Bug also confirmed by.

For I had a shocking experiance with ignoring a strange behavior of the safety switch with a copter,
I do not dare to continue with this issue.
Here the result after one week, nerves cutted should help to understand my wariness.

(kd0aij) #304

@ag-sys Nice flight, congratulations. The transitions at 1:22 and 2:40 look great to me, and you seemed to have good control on the final descent and landing. I’ll be interested to see how well it hovers in the wind. Thanks for posting the log, too.

What are the current spikes on the transitions?

(Alexi Gilbert) #305

I’m not sure what the current spikes are. There are also corresponding spikes on the CTUN.ThrOut graph but not on RCIN.C3. The motor / prop combination will pull about 25A each on 3s so 58A seems about right for full throttle spooling up.

The motor mounts are made of 2mm ply wood, same dimensions as the Flite Test Mini Arrow.

I’m also interested to see what happens in the wind. Today it’s 15 - 20 mph so a little too much for my liking. I want to work up to that level gradually. I’ll be trying out QLOITER on my next flight too.

(tridge) #306

you’re right, and I’ve reproduced the issue here. It seems to be specific to Pixracer. I’ll see if I can find the bug soon.

(tridge) #307

I’ve done a PR to fix this:
The Light looks like:
it should go into master in the next day I expect

(lorbass) #308

Thank you verry much, I’m happy!!!

Still waiting for new props.

( research air) #309

Hi Tridge,…is it yaw +tilt ? I am getting servo throw that sometimes point 180 deg in opposit direction to the point that the props will hit the mounts but not consistently? this is on illusion with 180 deg servos I can reprogram the servos for less throw, what paramiter to reduce yaw and tilt on the tilt servos?

(adlaif) #310

Hi Tridge et al. Could the master be adapted to fly a quad motor tailsitter? Something like

(tridge) #311

yes, it could be, but it would require some significant code changes. I do have that one on my list of vehicles to support, but I doubt I’ll get to it for a while. The key thing it needs is to be able to use AP_Motors when in fixed wing flight for rate control

(kd0aij) #312

I discovered that APM Planner2 had most of the KMZ export functionality necessary to display aircraft orientation from DF logs. Current WIP is in

This is what my first attempt at a back transition looked like. (blue line is FBWA, green is QSTABILIZE)

(tridge) #313

very nice!
I can see this being very useful for analysing logs from users

(Iam) #314

Mission Planner will do this too using Create “KML+GPX” and clicking on “Models” in the KMZ in Google Earth

(Alexi Gilbert) #315

QHOVER and QLOITER work well in calm conditions so any problems must be airframe issues. Transitioning from FBWA to either of these modes is a bad idea on my plane. As the nose comes up it gains altitude, causing the engines to shut down as it tries to get back to the altitude where the transition started and the attitude goes wonky. Sometimes it recovers and sometimes it can’t catch it in time.

Wish I had some advise about wind other than avoid it. As you suspect, the most stable way seems to be head on. I tried sideways but I can’t give it much roll before the torque and associated yaw gets too much for it. I’d like to try increasing the maximum pitch angle to 90 degrees in Q modes. Is that possible? Can I set a roll limit and max yaw rate for Q modes somehow?

(tridge) #316

if what you want is to be able to pitch forward a lot you could set:

  • LIM_PITCH_MIN=-7000
  • Q_ANGLE_MAX=7000
    the roll limit will come from LIM_ROLL_CD, and that wiill give you a 70 degree pitch range. It will also affect FBWA mode though, and that may be too much.

(kd0aij) #317

I’ve been working on the KML exporter in APMPlanner2 to help in analyzing tailsitter flightlogs. Here’s an example animation of a short QStabilize flight including takeoff and landing (tip-over backwards) done in Google Earth. The attitudes are taken from the XKQ1 (an EKF3 attitude quaternion) records and correctly represent the nose-up orientation during flight. Animation speed is 2X realtime. Link to mp4:

(kd0aij) #318

@tridge New Qstabilize flight log on latest master with the Stryker (AUAV-X2) log 50 in this folder:
I think the PID tuning is pretty good now. There’s also a …50.kmz file in that folder which contains plane models showing EKF3 attitude XKQ1 at 5Hz. I think that’s working pretty well now.

(tridge) #319

that’s looking pretty good now!

that didn’t work for me. I opened it in Google Earth on windows10, and it just shows the whole planet. It doesn’t zoom to the flight area. Even selecting one WP doesn’t work.
After I get the lat/lon from the log I can find it, but it just shows some green squiggly lines.

(kd0aij) #320

GE should fly directly to the right coordinates when you open the kmz file. The green line is the flight path, which is enabled by default.
Here is a snapshot of what I see immediately after opening the kmz:


By default, the plane models are not displayed, since they can bog the display down, so it’s a good idea to select a small time range using the “time slider” at the upper left of the map. This is what you should see after checking the EKFattitudes box, selecting a short time interval and zooming in:


The “Attitudes” folder is based on the ATT record (AHRS_VIEW roll/pitch/yaw), so it will be rotated 90 degrees when in Qstabilize mode. The EKFattitudes folder is calculating Euler angles from the XKQ1 quaternion.

I’m running Google Earth (64 bit) on Ubuntu 16.04