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1
Indeed that would be very nice to have but surely be a considerable effort.

Meanwhile, the wing that is intended for FPV flight will be fine to use.

Just wanted to share a video to illustrate the position hold, starts at ~2:30 and all the way to close before landing at ~13:30 something. I think i might have switched over to attitude mode once in the middle of that since i got scared it got too low altitude and then went back to pos hold.
I only have the low resolution fpv version of the flight.

https://drive.google.com/file/d/1KITYJ8vshnRfQO6ptpx4_oon-ler1yqi

There is just a weak wind of like 2 knots (1m/s) coming from the sea.
It behaves surprisingly well (what i am used to) and is interesting and entertaining to see what the fc will do.
Mostly it flies in counter clockwise circles but not always. It will rise and run at pretty low speed going towards the sea but increase speed and sink going away from it (with the wind). It picks up altitude again after it starts to make a turn to left or right. I noticed on the flight logs that there are very often autopilot warnings during pos hold, but not always. I don't know the reasons but assume it could be crossing some limits for speed, banking etc etc.

Anyway, the season for wing flying is over for this year for me - it was a good one.
2
I've got several fixed wings that do waypoint (including altitude changes) and RTB, but I did several changes and hacks to get it working:
- The altitude and throttle was oscillating.  It would go from stopped motor to 100% throttle, especially during Position Hold.  I should have spent more time trying to get the PID adjusted, but I set FWPF min and max thrust to some values that tamed this down and set Min and max airspeed to the same number which was a reasonable cruise speed.  There are different alarms for FWPF min/max airspeed and for SystemSettings min/max arispeed.  (settings hacks)
- I increased the max bank angle so that it would stay closer when doing Position Hold.  (settings change)
- Especially with the increased bank angle, in a turn it would drop the nose and loose altitude before adding elevator.  I added a code change that starts off with a reasonable amount of elevator, so it does more of a normal turn, rather than bank, drop the nose, finally add some elevator.  (code change)
- Waypoint flight would never get past the first waypoint or 2 without returning to the first waypoint.  This is because of the various airspeed alarms that were happening (partly because of my airspeed and thrust settings hacks).  I set Error Destination to -1 on each waypoint to get it to ignore this, and waypoints worked fine.  (settings hack)

Certainly a lot of hacks that I need to clean up.  :(  Fixed wing GPS flight needs a detailed set of instructions that can guarantee good GPS flight if you start with an airplane that flies good.  It should be possible to set up both a 3 channel high dihedral powered glider and a 3D stunt airplane.

Figuring out and writing a good complete set of setup instructions for fixed wing GPS flight is at the top of my wish list.  The code change to add elevator as soon as it banks would help too.
3
Vehicles - Fixed Wing / Re: Position hold on a fixed wing - Altitude control mystery
« Last post by karla on November 16, 2019, 08:15:04 am »
Thanks a lot Cliff for clear confimation.
plus all extra resources and experience on what can possibly be done about it.

Start and landings always in attitude mode. Before, when ins13 was not reliable and also during setup of servos I did fly rate so I know all is nicely centered. Now attitude is very convenient to use at most times.
No real problem with pid windup here, maybe because I reboot and arm very shortly before I take off generally. After getting a good altitude I have experimented mostly with Position hold and RTB.

Since its been taking a long time and effort to get to point I am today and now learning there seems to be no proven solution for getting a mako to do position hold when there is wind, I am seriously considering to migrate over to another platform for these wings. To control altitude is crucial for trying waypoints and complete missions. 
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Vehicles - MultiRotors / Re: Position hold not working
« Last post by TheOtherCliff on November 16, 2019, 04:04:30 am »
The increasing oscillation (with a period of about 4 seconds for me) is caused by the DJI/Naza GPS smoothing and thus delaying the GPS data.  Just like when you use slow ESCs you get (much quicker) Attitude mode oscillations.

There is a workaround here until the cause found in either the EKF configuration (tweakable in the GCS) or the flight code is changed to take this into account.  There is pre-compiled firmware for 16.09 and source code for you to build your own version of whatever else you are using:
https://forum.librepilot.org/index.php?topic=3012.msg21154#msg21154

Or now that we have your configuration working, you could also try going back to your previous GPS and see if your mag issues are small enough to allow you to fly.
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Vehicles - MultiRotors / Re: Position hold not working
« Last post by trust on November 16, 2019, 02:17:02 am »
I did some more testing of VelocityRoam and RTB. They both seem to be working basically fine, but in both cases, if the quad sits in one position (or when RTB returns to the base point), it seems to slowly sway tilting from left to right, right to left, with an amplitude that slowly increases centered around one point. It doesn't just sit. There is also a slight rearward drift in VelocityRoam. Is there a way to dial these out?
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Thank you for your reply just wonder I have this DJI faulty gimbal but there also are ESC build in, together with motors and encoder. maybe there is a way to use it. It is only matter to read colour coding on them there is 6 colourful wires.
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General Discussion / Problem with USB - Revolution
« Last post by Blauner on November 15, 2019, 08:53:41 pm »
Hello everyone,
I have a problem with my 2019 MacBook Pro - Catalina 10.15.1, when I connect the flight controller -Revolution-, the LibrePilot program does not recognize the device.

Note:
these devices are displayed:
-tty.usbmodem14401
-cu.usbmodem14401

Has anyone experienced this problem?

MacBook Pro 2019
Mac OSX: Catalina 10.15.1
USB: USB-C
LibrePilot: 16.09

Thanks.
8
Italiano / Re: informazioni su cc3d com computer mac
« Last post by Blauner on November 15, 2019, 08:45:09 pm »
Ciao,
io ho lo stesso problema, quando collego il Revolution a LibrePilot non riconosce il dispositivo.
Ho un MacBook Pro 2019 con installato Mac OS Catalina 10.15.1, non sono riuscito al momento a far funzionare il Revolution, te per caso hai risolto il problema?

Grazie.
9
What mode were you flying in that video?  Especially takeoff and landing.  Attitude mode takeoffs are usually a problem because of PID windup.

Fixed wing hasn't received the love it should.  Indeed, the coded way to increase altitude is to add power and as I recall, the coded way to decrease speed is to climb.  So e.g. when following a waypoint course, it adds power, and after a while it starts to climb.

There are some "cross feeds" that are designed (my understanding) to make this work more quickly.  I haven't played with them.  The units in System->Settings->FWPF are what you have to try to figure out how you might change them.  FWPF setup is not intuitive for a model pilot.  :)

One reason I can imagine for doing it this way is that you won't ever stall by asking it to climb too quickly or by asking it to climb with a dead or failing motor.

This algorithm seems to also fit well where you trim a commercial aircraft for best fuel economy and want to keep it trimmed that way.  Also, commercial aircraft change attitude / altitude slowly as compared to models.

I've made several comments about this over the years, among them that:
- If you determine that you need to increase altitude quickly, this is not effective.
- If you want to make a terrain following aircraft, it will crash when flying toward a hill if you give it a normal climb command.
- The way the physics works, it seems to me much better to instantly climb with elevator which causes a gradual slowdown that can be offset by adding power. Conversely, if you only climb by adding power and then because increased speed causes the code to pull up elevator, then, well the aircraft doesn't come to full speed instantly and the climb is delayed.
- The statement was made back in the OP days, that all airplanes climb when you add power, but that isn't true.  It may be true that the design of full sized aircraft works this way, but many models are designed so that adding power neither climbs nor descends and if your aircraft is built (e.g. tail heavy or motor in a pod over wing) so that adding power forces the nose down, then some aircraft even descend when adding power.

One of the things on my wish list of things I would like to do is a different FWPF that uses elevator to climb.

Some related threads:
https://forum.librepilot.org/index.php?topic=4644.0
https://forum.librepilot.org/index.php?topic=3518.0
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Vehicles - Fixed Wing / Position hold on a fixed wing - Altitude control mystery
« Last post by karla on November 15, 2019, 08:04:50 am »
Hi all  :)

last summer I had some great weeks flying my mako fixed wings.



One has a Revolution board and the other a Revo Nano and both controlled via OPLINK from ground tx.

I first upgraded to the official 'latest' Librepilot version 16.09 +r782
https://forum.librepilot.org/index.php?topic=4580.0
This version finally feels like a mature code when it comes to the magnetometer calibration and using the Attitude Estimation Algorithm set to GPS navigation (INS 13).
I found it stable and predictable on my fixed wings (finally :) )



So far so good.
I made many flights to try out Position hold under INS13.
I have some experience and some questions.

It seems when the altitude is getting low, then the fc will try to increase it, but only by increasing the rpm of the motor.
Is that correct?
One could have thought that adding a bit pitch would be included in the code, but it does not seem that way.

Would be great if anyone (cliff :) ?) could confirm this.


I can upload other videos of what happens in good wind conditions (no wind, and some 15 min of successful pos hold) and another (more than one) what happens if trying to increase altitude just by using rpm increase when going down-wind (doesn't do the job unless you are at very high altitude).
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