APM:Plane double release 3.5.3 and 3.6.0beta1

3689651507?profile=originalAs mentioned on the 3.5.2 release discussion we have decided to do a 3.5.3 release to fix a couple of important bugs found by users in 3.5.2.

The main motivation for the release is a problem with flying without a compass enabled. If you fly 3.5.2 with MAG_ENABLE=0 or no compass attached then there is a risk that the EKF2 attitude estimator may become unstable before takeoff. This can cause the aircraft to crash.

The other changes in the 3.5.2 release are more minor:

  • fixed loiter radius for counter-clockwise loiter
  • fixed the loiter radius when doing a RTL at the end of a mission
  • provide reasons to the GCS when a uBlox GPS fails to properly configure
  • support a wider variety of NMEA GPS receivers
  • use EKF1 by default if no compass is enabled

For those of you feeling a bit more adventurous you might like to try the 3.6.0beta1 release. There is still a fair bit more to do before 3.6.0 is out, but it already has a lot of new features and I have been flying it for a while now.

The biggest single change in 3.6.0beta1 is the update of PX4Firmware. This brings with it a lot of changes, including much better support for the Pixracer flight board.

There has also been a lot more work on QuadPlane support, which a new QRTL flight mode, plus support for using the forward motor in VTOL flight and active weathervaning support. If you are flying a QuadPlane you'll find the names of the copter rate control parameters have changed (just like they have in copter). You should be able to find the new parameters OK, but if not then please ask. I'll provide more detailed documentation with the final 3.6.0 release.

Detailed changes in 3.6.0beta1 include:

  • merge upstream PX4Firmware changes
  • new AC_AttitudeControl library from copter for quadplane
  • modified default gains for quadplanes
  • new velocity controller for initial quadplane landing
  • smooth out final descent for VTOL landing
  • changed default loop rate for quadplanes to 300Hz
  • support up to 16 output channels (two via SBUS output only)
  • fixed bug with landing flare for high values of LAND_FLARE_SEC
  • improved crash detection logic
  • added in-flight transmitter tuning
  • fix handling of SET_HOME_POSITION
  • added Q_VFWD_GAIN for forward motor in VTOL modes
  • added Q_WVANE_GAIN for active weathervaning
  • log the number of lost log messages
  • Move position update to 50hz loop rather then the 10hz
  • Suppress throttle when parachute release initiated, not after release.
  • support Y6 frame class in quadplane
  • log L1 xtrack error integrator and remove extra yaw logging
  • limit roll before calculating load factor
  • simplify landing flare logic
  • smooth-out the end of takeoff pitch by reducing takeoff pitch min via TKOFF_PLIM_SEC
  • added support for DO_VTOL_TRANSITION as a mission item
  • fixed is_flying() for VTOL flight
  • added Q_ENABLE=2 for starting AUTO in VTOL
  • reload airspeed after VTOL landing
  • lower default VTOL ANGLE_MAX to 30 degrees
  • Change mode to RTL on end of mission rather then staying in auto
  • implemented QRTL for quadplane RTL
  • added Q_RTL_MODE parameter for QRTL after RTL approach
  • reduced the rate of EKF and attitude logging to 25Hz
  • added CHUTE_DELAY_MS parameter
  • allow remapping of any input channel to any output channel
  • numerous waf build improvements
  • support fast timer capture for camera trigger feedback
  • numerous improvements for Pixracer support
  • added more general tiltrotor support to SITL

I flew both 3.5.3 and 3.6.0beta1 today and both are really flying nicely. I hope you all enjoy flying it as much as the dev team enjoy working on it!

Happy flying!

E-mail me when people leave their comments –

You need to be a member of diydrones to add comments!

Join diydrones


  • Developer

    @Keeyen, thats a great log, thanks! Paul and I had a good look at it. We don't yet have an explanation but we're working on it.

    We'd appreciate it if you could keep the aircraft config exactly the same for the next couple of days. We are likely to ask you to run the test again with a new firmware that will log some additional information. So we really need to keep the aircraft as close to its current state as possible.

    Also please note where you had the aircraft at the time, and any metal around it. That could be critical to reproducing the problem with the additional logging.


  • 100KM

    Dear Andrew

    I'll do as what you have instructed and report my finding. I'll also change the original SD card with ScanDisk micro SDHC UHS-1. FYI, I'm using original 3DR Pixhawk for my Skywalker as a test bed.  

  • Developer

    @keeyan, you can also raise LOG_FILE_BUFSIZE to give more memory to logging to reduce the change of losing log messages.

  • Developer

    @keeyen, I'd love to get DF logs showing that issue. If you can setup logging while disarmed (set LOG_BITMASK to 131071) and get DF logs showing the attitude going off that would be greatly appreciated.

    It would be ideal if you could do this with 3.6.0beta1 or with master as that will provide more useful logs. The 3.5.3 logging tries to log the EKF data at too high a rate for most microSD cards to keep up, so you end up losing log messages. To be useful for diagnosis and to fix this problem we need a log with no lost messages. In 3.6.0beta1 you can look at the PM.LogDrop message in the log to see how many lost log messages there are. That really needs to be zero. You may need to get a high quality microSD card for that.

    Do you have time to help us with this? I don't see the issue on my aircraft so your logs would be very valuable in ensuring we get this fixed properly.


  • 100KM

    Dear Andrew

    Thanks for the update. I've install the this firmware 3.5.3 and notice some issue during bench test.

    I'm aware of the compass issue. But it actually also doing the same error with MAG_ENABLE = 1 with the previous 3.5.2 firmware. I have a near miss during a test flight but luckily save with manual mode. Yesterday I updated to 3.5.3 and during  bench test, I put the plane in open space to get GPS signal and suddenly the pitch and roll go haywire as shown in HUD while the plane was stand still. Unfortunately I can reproduce the same problem this morning but do notice that once I put the plane back indoor, without GPS reception, the EKF turn red. Velocity - RED, Position ( Horitz ) - YELLOW . Is this going to cause problem if GPS signal temporally lost during auto flight ? 

  • Developer

    @Hellcat74, Y6 can be used with quadplane in the 3.6.0beta1 release. I also have experimental code that supports tiltrotors, including tiltrotor Y6 setups like the FireFlyY6. I expect that to be in the final 3.6.0 release.

    It also supports tri, tilttri, hexa, octa, octaquad and of course quad

  • Hi Tridge what configuration can quadplane handle? Would be great if a Y6 could be used.
  • Thank's Tridgell, I remember to read something about but I couldn't find now and was no shure.

  • you are right tridgell

    on top of that pixhawck is really cheap team loose time to work again on the old apm..

This reply was deleted.