Motor spin slow than others

Posted by Cristian Rougier on April 29, 2013 at 3:59pm

Hello, all , im working with APM 2.5, in X configuration, when i arm the APM, one motor (motor 4) spin slow than others 3.

When i calibrate the ESC's in automatic mode, all spin with same speed and work fine, but when
 i arm the APM and test, motor 4 speed slower. 

I changed the motor, but this continue...

Some configuration?

Any help?

Regards

Cristian

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Replies

  • ben November 14, 2015 at 10:21am

    Hi, I've just figured out I have the same issue here ( GE260 folding frame with mini APM 3.1 controller )

    - Motor#3 ( back left ) spins slower than others at low throttle commands ( approx less than 30% )
    ESC and motors are soldered, so I really can't swap them for testing, used to shorten previous #3 ESC one year ago .. replaced it, everything was fine using FLIP32 controller, issue appeared as soon as using the Mini APM.. thought it was some PID settings misconfiguration at first glance ..

    I did recalibrate the ESC then ( 4 at the same time ), at "slow" takeoffs the quad flips over itselfs in the #3 direction .. with a quick "40% throttle burst" the motor #3 will behave like the others, allowing a regular takeoff, stabilized, everything's fine ..

    Until I want to reduce my altitude, it most of the time results in a destab into #3 avis, then the quad reacts, bring it back, and destab again in quite a "funny" dance which ends only I if i use the pitch / roll command or throttle up a little bit .. everything's fine again

    At some points, it might lead to a crash ( as testing RTL , the AltHold mode, sometimes has baroglitches, resulting to altitude drop, same #3 issue and crashes this way, or at lower battery levels, it never compensates enough the motor #3 glitch and crashes again .. )

    - Here's a basic scheme of my problem :

    oQr1N.jpg

    Thanks for any help, notes, ideas ;) 

    Cheers :)

    • ben January 30, 2016 at 12:18am

      Hi, except PID tuning and radio's trimming here are the main differences with mine :
      ( did this with np++ excelent compare plugin .. )


      BAROGLTCH_DIST    250  500  ( yeah I do have some baroglitch appearing, and hate having them in auto / rtl mode -> this causes altitude loss and further unstabilities )
      ARMING_CHECK      1      0     ( arf )


      DCM_CHECK_THRESH    5=>0.8
      EKF_CHECK_THRESH     0=>0.8   ( put it to 0 because this caused me auto-mission to land in the trees once waypoint one reached )


      THR_ALT_P                     0.4 => 1 ( had huge stability issues when loosing altitude, some flips etc .. leaded to previous crashes )
      MOT_SPIN_ARMED         0=>70
      POSCON_THR_HOVER    461=>513

    • Hollis Inman > ben January 2, 2016 at 8:47am

      Did you have any luck figuring this out? I've had a similar issue... my faulty position will actually cut out completely if I lower the throttle too quickly.

    • andi azhar > Hollis Inman January 9, 2016 at 8:04am

      its seems new diy builder having the same problem, hehe, i face it too, and still searching for the solution, omg

  • Cristian Rougier April 30, 2013 at 2:47pm

    HELLO i checked in status and channel 4 output is lower than other channels.

    I tested in low and high speed, Please see the attached images.

    Can you help me to correct this please?

    Regards

    Cristian

    channel4_at_low_speed.png

    channel4_high_speed.png

    https://storage.ning.com/topology/rest/1.0/file/get/3692702548?profile=original
  • Cristian Rougier April 30, 2013 at 8:53am

    I changed all ESC's to CX-ESC-40A , and the problem persist, motor 4 spin slow

  • Cristian Rougier April 29, 2013 at 8:28pm

    Hello all if i change the output s3 to s4  (and s4 to s3) now motor 3 work bad and 4 fine, so may be the ESC ?

    is a new Hobbywing Skywalker Quattro 20A x4

    I repeat that all motors work fine in calibrate ESC mode single or automatic.

    Im testing without props, im checking the motor force comparing with finger..., now i can stop motor 3 with my finger, others not...

    Cables to motors are:

    Black to B
    Red to A
    Yellow to C

    i change A to C to change the orientation.

    What strange.. some help?

    Regards

  • Warren Purnell April 29, 2013 at 4:57pm
    I find that on spool up prior to takeoff one motor may spool slower. Once at takeoff speed and as it leaves the ground all is OK.
    I too think it's just adjusting against sensor inputs that aren't familiar while in contact with the ground. May also be an effect of ground resonance. Just my guess.
  • OG April 29, 2013 at 4:53pm

    Sounds like the connection between the ESC & motor is bad remove bullets & join connections directly together. setup your motors & ESC in CLI mode. turn on radio first set throttle to max power on copter to program ESC REMOVE PROPS !!

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