ArduPlane 2.73 released

I've just released ArduPlane 2.73 as a bug fix release for several important bugs in 2.72

The main reasons for this release are:

  • fixed a noise and scaling problem with airspeed sensors
  • fixed a potential flyaway problem with the L1 navigation controller
  • improved handling of poor GPS velocity for attitude correction

This release does not contain the new attitude controllers that I previously said would be in 2.73. Paul and I decided that it would be better to hold those over to the next release, and get this release out with just the above critical bug fixes.

The airspeed problem stemmed from a changed introduced in 2.72 to make ArduPlane automatically scale analog inputs with board voltage. That change was good for voltage and current sensing, but it added a lot of noise to airspeed sensing as the 3DR airspeed sensor is ratiometric (the sensor output scales with the supply voltage). The fix was to add support for ratiometric analog inputs. This release also fixes a bug in the airspeed ratio handling. To confirm the fix I have been driving around in my car with an APM2 and PX4 logging airspeed and GPS speed - that test confirmed the airspeed sensing is now accurate.

The flyaway bug in L1 was caused by an unusual situation where the previous waypoint was equal to the next waypoint, which can happen when a mission is interrupted and restarted. The L1 controller would then level the wings and fly straight ahead until the operator intervened. The bug fix was to make the L1 controller detect this situation and track directly to the next waypoint. I don't think many users would have seen this bug, but it definitely could happen and warranted a bug fix release.

The GPS handling bug was related to the MTK GPS, which can be very slow to report loss of GPS lock, which could lead to very poor attitude from DCM and even a crash if the plane tries to turn while the GPS is reporting incorrect velocity information. The fix was to watch the satellite count, and stop using the GPS velocity for accelerometer correction when it had less than 6 satellites. This is selectable with the new AHRS_GPS_MINSATS option.

Other changes

While this release doesn't have the new attitude controllers I decided to leave in some other smaller changes that have been made since the 2.72 release that I consider to be low risk, including:

  • fix the PX4 barometer driver to run at full rate
  • fixed handling of a saturated compass on PX4
  • added COMPASS_ORIENT option to support external compasses
  • fixed the compass in HIL simulation
  • added GCS messages to flash logs
  • allow 3D accel calibration over MAVLink
  • Added new ELEVON_OUTPUT option
  • removed MANUAL_LEVEL option (manual level is now always on)
  • improved pitch handling when inverted

Of these, perhaps the most useful is the ELEVON_OUTPUT option. That makes it possible to setup your transmitter with normal aileron/elevator and get the APM to do a software elevon mixer on output. That gives better control in FBWA mode than the previous elevon options.

I recommend that all users of 2.72 upgrade to 2.73. Happy flying!

Cheers, Tridge




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  • Tridge,

    I had a couple of flyaways with 2.72. It happened when I restarted a mission. As you said, wings-level flyaway. I had to create a new mission and upload it before the plane would respond.

    Thanks for the fix.  

  • Hi, 

    I have uploaded 2.72 release, in case that I would like to come back to 2.68 release  again, what should I do?.

    Is there any speciall procedure or we can do it from the mission planner, firmware screen choosing the 2.68 release

    Thank you.

  • I upgraded to the latest mission planner version and latest firmware for the 2.5 but now my skywalker will not hold altitude in any computer controlled mode. In manual mode it flies great, climbs / turns with plenty of authority and its trimmed so it flies straight and level hands off.

    when i switch to stabilize mode it does good roll stabilization and some pitch stabilization but it settles with 2-4 degrees of down pitch so that it slowly loses altitude. It used to hold zero pitch when i let go of the stick. 

    In RTL it goes full throttle and turns to home where it circles and slowly loses altitude. It used to climb or descend to the default altitude and hold it. When i switch to manual (to prevent it crashing into the ground) it has enough airspeed that it climbs quickly as soon as i switch over. i have min max and cruse set at 10, 22 and 12m/s but now its often flying 15-17 m/s air and ground speed in this mode.

    In AUTO it will climb to the auto takeoff height but then as soon as it heads to the first waypoint it begins losing altitude. It used to hold the altitudes or climb without any problems.

    I looked through the logs and this is what Im seeing.

    I start a mission in AUTO and the altitude error decreases till it reaches the target takeoff altitude which is correct. the nav pitch shows 15 degrees which is what i set for the takeoff climb and the pitch value also shows 15 degrees which means its climbing easily. 

    this is where the fun begins 

    As soon as it heads to the first waypoint the plane begins to descend and the altitude error starts to go up because it needs to climb to hit the target altitude. the nav pitch goes up because it knows it needs to climb but the planes pitch value doesnt budge and stays slightly negative so it continues to slowly lose anyway. Its flying at  12-14m/s which in manual mode is plenty of airspeed to climb and well above the minimum FBW airspeed.

    what control loop do i need to go tweek to fix this ?!

  • I get this error when trying to use GridV2 on MP 1.2.50.

    Also when I check the "Area" under Auto WP, it is showing "Area:-9548.23543215 m2".

    The error mentions an index that cannot be negative. Is this the problem?


  • Thank you for adding Elevon Output, that is a great feature.  The work you two have put into Aurduplane has been nothing short of amazing.

  • Hi Andrew,

    Thank you for the fixes.

    I give it a try in Xplane9 in HIL mode and checked the modes however the HUD display shows inconsistent angles.

    Actually it starts with around 90 degree positive pitch and later on all of the angles go crazy. I can only fly with manual mode.

    My configuration is: Xplane9, Missinon Planner 1.2.50, APM2.5, Turnigy 9X Tx/Rx

    I also checked my configuration with:

    Arduplane 2.72 behaves the same

    Arduplane 2.69 and 2.71 works fine


  • Thank you for the bug fixing.before you release the 2.73,I fly my skywlker(1680)and it appears the two cases(airspeed sensor,L1 algorithm).Now I use the 2.73 firmware,thank you for your hardworking.

  • Tridge -- thank you, you rock! This was a great move.

    I had some fly aways happen in 2.7.2 and thought it might have to do with WP telemetry data transfer errors but I never experienced that before 2.7.2. It always failed and gave an error or worked flawlessly in previous versions. 

    I would like to also continue testing the 2.7.3 beta (now 2.7.4beta?) with the new attitude controllers and happy to provide feedback. 

    Great work! I look forward to testing the new 2.7.3 production firmware.


  • Andrew, when are you going to enable gimbal control? And GRIDv2 not filling in the polygon. You had to have seen my many posts about this...

    It seems like 90% of people just use Arduplane for flying waypoints. But those wanting to map are plagued with bugs and no help. We are the minority but we still want a working product. I cant even use this for mapping because of the lack of gimbal control through DO commands, and the problem with GRIDv2, which I need for camera triggers...

     I don't understand how to beg harder than I already have for some assistance.

  • Andrew thanks for the quick turn around on a bug fix. I'll load up the firmware later on today and give it a whirl! 

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