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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  • So far RC5 is very good.
    I went from v2.9.1b, straight to v3.0RC5.
    Had about 12 flights so far, no issues at all.
    Considering how bad my vibrations are, the performance is excellent.

    JDrones, 880kv motors, 10" props, 3300mah batt, Sonar-off

    Z=0 to -25
    X&Y=5 to -5

    -holds very well...even on very windy days...tilts in nicely
    -on extremly windy days, it gets a a little bouncy
    -I can change position via stick movements and stays put when I let go

    -same as loiter...nice touch down

    - same as Loiter

    -very cool feature. Works very well
    -however one thing I could do without is that it turns towards you when the mode is engaged. its should stay pointed in the same direction it was armed!  
    Randy, should be easy to code right?

    -so much better than v2.9
    -finally goes to the proper Alt of the WP
    -seems smootehr overall
    -WP changes are quicker (some times ubrupt, but still in to watch)
    -again...way better then v2.9.
    -the decent is sooo smooth...even on windy days
    -after some of the latest code changes I was expecting the copter to turn away from me (just as it was when it first took off.
    for some reason, it only turns 90 degrees instead of 180
    would be nice to have it turned with the back facing me, upon landing.

    -haven't see any upgrade changes when into this mode
    -then didn't seem to do much.  it just  moved very slowly
    -didn't bother testing to much..I think I need to increase the speed a bit

    So overall...10+ so far....excellent work....Arducopter has come a long way!!
    I can do AUTO missions and GUIDED modes with confidence.

    One more thing I'd like to add, about the MP...a bug  I think.
    When in GUIDED mode. 
    Telling the copter to move to a new location, brings up the Alt box.
    You enter the ALt and hit all is good.
    BUT...on the second and further movements, the Alt box no longer comes up.  So you ar forced to use teh same Alt.
    In the prev version of MP, the Alt box would come up every time you set a new WP.
    Your prev Alt was there and you could change if you wanted to.
    It was way better this way.
    not sure if it was changed on purpose, or just a bug.

    anyway...long enough post!!



  • Randy,

    Thanks for your compassmot calibration video tutorial on youtube.

    It helped out alot and cured the toilet bowl effect on my tricopter.

    So far, firmware v3rc5 is performing well after doing all the necessary prerequisite steps ( i.e. conducting the compass live calibration and the compassmot calibration).


    Hopefully, it stays this way. 


    Will there be a release candidate #6?

  • is version 3 anywhere on the horizon yet?

  • I'm using v3rc5 with apm2.5 and when I'm using alt hold it will momentarily switch to stab for about a second and then switch back. Has anyone else experienced this? It doesn't happen every time. Just once in a while. Next time it does I will upload the log.

  • Maybe it is possible to set the SBAS system direkt to the GPS. I read that sometimes in Europe the receivers got WAAS Signals, alltough in Europe they should only use EGNOS. I don´t know if its possible, but it should give a much better accuracy. Maybe it is OT but maybe someone could give a try?

  • Hi Michael,

    I didn't try to blow on mine, but will do it soon. On weekend I will do some tests on how to shield GPS antenna against electrostatic charges. As I told already, I think such effects usually happen in aircrafts. What does Boing or Airbus against that??

    The question is what kind of material is useful without dampening signal strength or causing a frequency drift in oscilator. Unfortunately I don't own a spectrum analyzer. So in my opinion I have to use material with low dielectric loss factor i.e PTFE, polyethylene or oily paper. It's worth a try and hopefully I can trust HDOP value from GPS.

    Randy: I've thought about the workaround I mentioned before. 

    #1 add a warning that you have to take your phone out of the pocket during calibration steps.

    #2 try and catch differences in GPS coordinates that are quite to big within a specific time.

    #3 add HDOP to the arming check list with user adjustable value.

    Reason: Satcount isn't the one and only indicator for a good signal strength. You can have 5 or 6 sats in a row(in space) but you only have a HDOP of 6. That's really bad for precise orientation! On the other hand If you have only 4 sats in a cross you can get a HDOP of 2,5 which is good. In best case 1,0 is possible, but I think for example 3,0 should be the upper limit. What do you think?

    Is anyone here who can confirm?

  • Thanks a lot.
  • real scary fly away in  V3rc5

    there was no wind so I tried stabilise mode wich went quite fine for a time. all of a sudden the hexacopter takes off to the left 

    and there was nothing I couldt do to stop it. it didnt resond to the radio at all. it was about 15 meters away from me when it happened. When I arrived at the crash site 50 meters away, it was still trying to dig a hole about 90 cm in dia. so I pulled the plug on it.

    and now I am a bit mad at myself and a bit mad at the apm board. this is getting to be a very expensive hobby with all those crashes. I hope someone can tell me what went wrong just before the crash.


    2013-06-10 22-06 1.log

    2013-06-10 22-06 1.log.gpx

    2013-06-10 22-06 1.kmz
  • Hi!

    Radovan, my geographic declination should be 2,14° that equals 0.038. I used Autodec many times before and ended in only 1,4°. So I do it manually now.

    Do you remember, if you have had your cell phone in your pocket? Only friday I had it in the pocket.... Maybee there are some interferences?!?!

    MHA: GPS is very sensitive due to touching on antenna. And like magnetometer more sensitve to negative/positive charges during flight. Some people remember now their army time. Never touch the ground while the helicopter isn't grounded yet!

    I believe there is a possibility that we also have such kind of effect. Especially with non conductive propellers? Thats like a tesla generator from shool, isn't it?

    Randy: I've found some interesting behaviour in my logs. They're from RC4 and I can't remember what happened. You can see Vcc in comparison with GPS values. There is only APM with GPS and telemetry connected to an ESC. I'll change that and also try to stabilize the power supply with some strange capacitors..3692740762?profile=original

    2013-06-04 18-35 6.log

  • Hello, I'm Steve and I have a quad copter with arducopter. My quad copter has propellers of 7" and my motors are from "hobby king" (ST 2004 Donkey). With all these my quad copter has problems with PID's and I'm a little bit fool, I don't know what I have to do.
    Please help me.
    ▶ Reply
This reply was deleted.


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