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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  • Developer

    I've now released APM:Plane 2.74

    Thanks to everyone who contributed! Please give feedback on the new release in the 2.74 release thread.

    Cheers, Tridge

  • Moderator

    Please could someone clarify the ARSP2PTCH_P and ALT2PTCH_P parameters, what they do and their effect on level flight?

    On another note: today I tried "takeoff", I loaded a mission which consisted of "1).Takeoff @ 20° to 50m 2). loiter @ 50m AGL unlimited", the first time worked great, the motor started as soon as I hit AUTO but the climb out was not very steep but no problem, I landed and tried again. The second time the motor wouldn't start and even clicking 'Restart Mission' would not get the mission to run again. Is there something I'm missing?

  • Is it normal for the amp to register a altitude of several hundred feet on every start up? I re-set to zero each time but was wondering if I missed a setting so that it would do this automatically on start up just as it sets RTL each time. Or... if not perhaps there is a valid reason for it not to do this? Thank you!

  • Hello, I cant get my elevons to move up and down more than a couple mm's, where do I adjust that?

  • Developer

    I've just done a new ArduPlane 2.74beta3 release

    This release includes the great new TECS speed/height controller from Paul, plus the new attitude controllers and a new ACRO flight mode that was requested by Pieter, Thomas and Soren.

    Please test it as much as you can and give feedback in that discussion thread.

    Cheers, Tridge

  • Hi Andrew,

    Would it be possible to add a current based compass compensation functionality like in ArduCopter 3.0's compassmot?

    I have moved the APM in Skysurfer as much as I can but I still see some interference and it looks like compassmot like functionality would be really useful.



  • Moderator

    Tridge, any chance of a Mission Planner-initiated "auto take off followed by a loiter at x altitude" sequence? Currently, I think this can only be done by a preloaded mission.

  • Hi
    Sorry if I'm posting in the wrong place, I'm setting up my APM 2.5 and have many questions, the first is about Failsafe
    I did the Failsafe setup and it is working ok, when I turn off the radio I can see changing flight modes in MP as expected (first circle after RTH). one thing does not happen as I expected the throttle not going to cruise mode. Even when I start with the throttle stick in the middle and turn off the radio the throttle goes to zero, is this correct? I expected the throttle to maintain cruising speed for the plane back home safely? (I did these tests on land and the GPS locked, I have no airspeed)
    (sorry for the mistakes I do not speak English and use the google translator)

  • Hi

    I was wondering if the ACRO mode will be available for the arduplane too?

    A plane stabilized without leveling would be great for normal flying (especially for FPV)

    I had a KK-Board with openaero in my plane before an I loved the gyro stabilization. The plane flew like it was on rails.

    Adding a KK board in series to the APM would be just stupid ;)  So what do you think?



  • @sergey, i had the exactly same problem with my skywalker which otherwise would fly fine in any auto modes in all the prior releases of arduplane. in my case what i found was  that the tailplane had come loose which is held down by two M3x25 screws. so when u put it in RTL the elevator tries to pitch the plane up slightly and a s a result the tailplane's angle of attack increases (since it was loose). this causes the plane to nose dive. my problem was solved when i tightened the two tail plane screws. but it took me a long............ time to find the cause. this time u put blue color thread lock on the tailplane screws.

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