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Quad motors running instantly on arming

Posted by Ken DAvies on January 9, 2015 at 2:08am

As you will realise I am a complete novice in this field and I don't know if this is the correct forum to raise my problems. I do not have a genuine 3DR APM but using a HK Pilot Mega2.7 FC but I hope someone can help me.

My kit consists of a Spektrun DX6 Tx with an AR610C Rx connected to the FC. Also a NEO7 GPS and remote compass. These are driving 4 Turnigy PLUSH25A ESCs. The ESCs are all connected to the FC by their 3 core cables. I have a PC card but at the moment powering the FC via the ESC BECs.The FC is set up via Mission planner 1.3.17 with the 3DR_QUAD_X4_RTF.param loaded, I assume these are the correct parameters. I have followed the set up procedure of the MP but I have struggled to get the Speed controllers to calibrate however they seem to be OK now except for the control via the FC.

I have been through the calibration processes shown here https://code.google****/p/arducopter/wiki/AC2_ESC and can now get the board to arm and the motors to run however although during the calibration process I have full control of the motors, when I arm the board the motors instantly run at about half spped and the throttle stick acts more like a switch. If I leave it alone the board disarms as expected after 10 secs. If I move the stick slightly up the motors instantly speed up to I would guess about 3/4 spped maybe more but no other response to the stick even up to full. Mode select is at stabilise, loiter and RTB do not change anything other than the board will not arm in those positions I assume correctly. If I move the board the motors change speed as I would expect as it attemps to level the quad if I had props fitted.

I have run the motor test facility in NP and the motors respond as expected.

Can any one Help, Any ideas?  Thank you in anticipation.

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Replies

  • Scott Reid January 17, 2015 at 3:29pm
    Assuming MOT_SPIN_ARMED is nonzero (default is around 80 I think), the behavior you are describing sounds normal. The motors spin at low speed when armed. When you advance the throttle just a little, it will quickly bring the motors up to closer to hovering speed.
    • Ken DAvies > Scott Reid January 18, 2015 at 4:44am

      Thanks Scott,  I think I got a bit ahead of myself without fully understanding the workings of the APM.  Have now changed the throttle response setting and all seems to work OK.  Just need a bit of calm weather to learn how to fly it.  Tried once so far and crashed, very short flight! no serious damage but noticed with this frame the motors very easily go out of alignment.

      Thank ypou for your input.

  • Zhen Liang January 9, 2015 at 3:05am
    Can u check ur full parameter list on mission planner and check ur THR_MAX value? Initially mine was 8 only and i changed it to 1000 and it was running okay already
    • Zhen Liang > Zhen Liang January 9, 2015 at 4:23am
      Just set ur throttle max value to 1000 and it will work accordingly already. No worries
    • Ken DAvies > Zhen Liang January 9, 2015 at 3:58am

      Thank you Zhen I have THR_MAX at 8%, THR_MID at 51% and THR_MIN at 13% all a bit odd, I don't know where these settings have come fromso that may be the cause.  Unfortunately I have just stripped it down to complete making an antivibration mount so cannot try at the moment but will give it a go asap. Fingers crossed!  Possibly one bit of the setup I have missed.

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