APM Copter 2.9.1.b has been released


APM Copter 2.9.1.b has been released to the Mission Planner and is also posted in the downloads area.
2.9.1b is a maintenance release incorporating changes to 4 default parameters that have been optimized since 2.9.1 was released.  There are also 4 minor bug fixes.  There are no code function changes or additional features.
The changes are:
1) reduce default INS_MPU6K_FILTER to 20hz
2) reduce InertialNav Z-axis time constant to 5 (was 7)
3) increased max InertialNav accel correction to 3 m/s (was 1m/s)
4) reduce yaw_rate P default to 0.20 (was 0.25)
5) bug fix for alt_hold being passed as int16_t to get_throttle_althold_with_slew which might have caused problems if you climbed over 320m.
6) bug fix for throttle after acro flip (was being kept at min throttle if pilot switched out of ACRO mode while inverted)
7) bug fix to acro trainer to do with roll correction 
8) prevent cli from being entered more than 20seconds after reboot.
Users are recommended to:
    Update Mission Planner to 1.2.41 and
    Update their flight code to 2.9.1b from the Firmware tab on Mission Planner. There is no need to go through a new configuration process in the Mission Planner.


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  • Is this video usefull to calibrate the motors? or there is possible to read vibrations in real time from the APM to calibrate the motors? Thank's

  • if my copter climb when switch to alt hold is that sign of throtle mid to big?

  • Hi randy,

    Is it safe to test the ROI on v3-R5 ?

    And also LAND ?

    This post said ROI being ignored :

    Thanks as always..

  • I just have time for test 3.0 RC5. Becauase, In Thailand have a raining everyday.

    Frame : Tarot Quad 650

    Motor : T-Motor MT4008 600KV

    ESC : T-Motor 40A

    Prop : 15x4

    Battery : Zippy 4s 8000 mAh 30C

    Radio : Turnigy9x Upgrade Frsky Mudule

    Hover Time : about  24 - 26 mins.

  • Randy,

    I was flying 3.0-rc5.  Switching from descend in ALT-HOLD or LOITER to STAB makes copter free fall immediately.  Apparently full throttle does not save if from 40 meter altitude and I hit ground.  That hurts.  Any parameters I can adjust to make it going higher throttle when  I put throttle stick to the top?

    Had same thing with 3.0-rc3.

    Also how I can make descent in ALT-HOLD or LITER faster than 1m/s?


    2013-06-14 05-27 3.kmz

    2013-06-14 05-27 3.log

    2013-06-14 05-27 3.log.gpx

  • How come the "APM input voltage" is no longer available to be entered in the Mission Planner-Battery Monitor?

  • Several days ago I’ve experienced a crash using v3.0.0-rc5. It was probably my fault but I’m not sure what happened. I was flying in stab mode, tried alt hold, loiter and land. Everything was fine. So after 9 mins of flying and when I was in stab mod my hex began suddenly slowing down and wobble than it inclined by 90° (nose down) and fell down from about 25 meters on the ground.

    At that moment, when it began slowing down I thought that it was in a battery failsafe mode configured with RTL so I tied to change the modes but I could not regain the control of it.

    So I would appreciate if someone could take a look at my logs and give me an opinion. (I’m a newbie with the hobby). Thanks in advance.

    2013-06-11 03-22 1.log

    2013-06-11 03-22 1.log.gpx

  • Major issue with RTL 3r5.. grounded till find out what is going on..

    Over the last several weeks,  I have had 3 separate sporatic runaways in the final stages of RTH, whether it is at the end of mission or de novo RTL.. Today I had been flying multiple missions ending with RTH without issue but with the final RTL around 10 feet I noticed a twitch in decent, sudden full thr and horizontal tilt, saved with STAB mode. All other episodes also occurred close to landing completion..

    3dr drone, wind 3-5 mph, radio T8FG, TFR4

    Are any gains to high?

    All mode parameters are tuned for smooth stab, alt-hld and loiter....  Thanks for any help..

    2013-06-13 13-21 4.log

  • Strange phenomenon...

    Yesterday I was out to our field to do some testing on 3.0rc5, which I like very well.

    Everything set, ready to go, but quad does not arm.
    Checking the mission planner (via telemetry) and HUD displays: check magfield.

    Indeed magfield was off scale at 770, pre flight check is working: very good.

    Now very bad: why is this value so high? As I didn't change anything on the quad.

    Anyhow I overruled the prefflight check as I wasn't going to use GPS for this test.

    For the record I did switch to loiter to see what will happen and quad was going in any possible direction no loiter at all.

    Back home I checked the magfield again, back to normal 320.

    I don't have an explanation yet as it is a plane open field.

    Anyhow my conclusion of last flight: pre flight check is working just fine and preventing from having surprises while in flight.

  • Gentleman,

    I want to run this idea by you.

    How about an Aluminium (Al) enclosure for the APM.

    The motor currents are AC (at a fairly high frequency) the magnetic field of our earth is "DC" ( see the "" ? )

    the AC currents induce an eddy current on the outside of the Al box. and shouldnt be visible on the inside of the box.

    The eddy's are transformed in heat and dissipated (the uW's wich get induced that is :-). the earth's magnetic field is not hindered by the Al box and our sensor measures magnetic north without a problem. (exept if you rotate the copter very very fast)

    What do you think?


This reply was deleted.


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