MultiWii ESC values for motor are off

[riahut.com]

He guys, please help me to figure out problem here:

When I arming my board (IOI) I see that values jump from 1000 to 1170 and motors start spinning right there.
1170 defined in #define MINTHROTTLE 1170 I have Hobbywings skywalker ESC.
But that I can adjust by playing with #define MINTHROTTLE 1170... correct?

But what bothers me alot that when frame with board rests on the table my ESC values so different, see picture, especially REAR_L


What to do?

BTW. I've tried ESCsCalibration procedure listed here - http://code.google.com/p/multiwii/wiki/ESCsCalibration
And have no clue if it successful as description of the procedure is very weigh and useless.

[Alexinparis]

http://www.multiwii.com/faq#The_motor_o ... l_RC_input

[riahut.com]

Thank you for the reply! But I believe this is not what you suggesting.
I can see something wrong because motor with lowest value start spinning very late, when throttle is all the way 50%, which is obviously wrong!
Note, that ESC were calibrated individually for throttle range by connected each of them to receiver so this is no ESC throttle problem, this is what FC sends on ESCs, I believe those values have to be identical or very close, not 50% difference.

[mr.rc-cam]

But what bothers me alot that when frame with board rests on the table my ESC values so different, see picture, especially REAR_L

When your model is sitting on a table the PID's are running open-loop (no practical feedback to attitude corrections). This can cause motor/ESC value offsets due the accumulation of the errors. The amount of this error can range from nearly nothing to really big values.

You have to go out and fly it if you want to accurately test the performance of the gyro and acc (in relation to the motor/ESC values). This will allow the model's attitude to react to the motor thrust changes and provide the proper feedback to the PIDs.

- Thomas

[riahut.com]

You have to go out and fly it if you want to accurately test the performance of the gyro and acc (in relation to the motor/ESC values). This will allow the model's attitude to react to the motor thrust changes and provide the proper feedback to the PIDs.

- Thomas

Great info! Thank you for explanation! But how can I fly If only 2 motors starts, then 3rd joins, and the 4th at 55% of throttle, quad will just flip over !!!

[riahut.com]

Just tried to fly, as I predicted, it flipped over because 2 front motors spinning full power when 2 rears barely spin. May be I missing some basic thing?

[chris ables]

I am running skywalker esc too and i have my minthrottle set at 1120 ! I had to calibrate mine 2 times before they synched together ! You need to solder together a cable with one male for reciever and 4 female for esc's and calibrate all 4 at once from reciever throttle channel ! Also i set my tx throttle channel to 100 % to calibrate esc's then readjusted the 1000 and 2000 on throttle channel in gui ! Hope this helps you ! And the gui motor levels will not run exactly the same in gui so you really cant go by that ! Good luck and let us know your progress!

[chris ables]

Also you need to calibrate the acc with your tx sticks the first time and then after that you can use the calibrate acc button in gui! And do not use bullet connectors on your esc's , be sure to solder motor wires - no connectors ! Connectors equal lots ofproblems in flight even if you think they are fine ! I have learned this the hard way and used to argue everyone about it until i started hardwiring my wires ! Turn your level P value to 5.0 in gui also !

[chris ables]

http://multiwii.googlecode.com/svn/bran ... -57721.pdf link to page with tx stick calibration and trim acc and calibrate acc ! And try to take off without acc on for first time . I think they lift off better without acc and then you can turn it on in flight to check it !

[riahut.com]

@chris ables
Thank you Chris for your advise, will try to do your recommendations first.

PS. What is the difference when I calibrate ESC individually and separately? For my KK board ESC calibrated individually were perfectly working.

[chris ables]

I think sometimes the tx doesnt go back to exact low and high throttle and if you make that cable then you can do all 4 the same time and you know they are synched since they get done together with one stick movement! It has nothing to do with board ! They just have to be in synch with each other and the tx to all work together!! Let us know what happens after you try all of this and best of luck !!

[chris ables]

Here's where i got that idea from with the cable ! http://witespyquad.gostorego.com/access ... cable.html

[tovrin]

i used some left over arduino breakout pins to make a 4-1 cable (just laid a bare wire down and soldered it to each pin and then to the white cable of an old ESC connector on the other side) , then ran a separate cable for RX power/ground. took longer to heat up the iron then it did to make the part.

But Chris' part is super cheap, if you want to wait fro shipping its very useful!

[chris ables]

Tovrin i didnt order one of these! Insted i took 2 servo y harnesses and made my own ! Ive seen pic of yours somewhere and it is nice also ! Calibrate all 4 at once from rx throttle channel works great !!

[Pyrofer]

I bought a servo tester off ebay that had 6 3pin connectors in parallel, great for testing all 4 motors and configuring them the same.
Only problem is its range isn't as large as it should be.

[riahut.com]

TeLet us know what happens after you try all of this and best of luck !!

Chris, I did like you seggested. Joined 4 in one and attached to Receiver TRR channel. Calibrated ESC usual way.
Then I calibrated ACC using sticks then I hit CALIB_ACC button in GUI.
Calibrated acto Gyro as well.

And you know what ?!

Still the same! but I've adjusted values of TX for Throttle channel using EP and Subtrims, so now I have 1000/1500/1978,
Still REAR_L TOP throttle value on ESC is 1470 and it spins slower than others

What to do?

[riahut.com]

I've created video to illustrate the problem I having.
Please take a look here http://www.youtube.com/watch?v=CMhBCFq_xEE

Appreciated for any suggestion how to fix the problem.

[chris ables]

You are still using those motor connectors i see in video ! You need to take those connectors off and solder those wires together ! I used to use connectors also and had those same motor problems ! NO CONNECTORS BETWEEN ESC AND MOTOR !!!

[chris ables]

Hey what kv motors are you using ? The timing comes set at low on default settings on the skywalker ! If your using higher than 1200 kv motors you might need to set timing on skywalkers at medium ! Timing can also cause motor problems ! I am running 1200kv motors and they are running on low timing and perform great !

[riahut.com]

You are still using those motor connectors i see in video ! You need to take those connectors off and solder those wires together ! I used to use connectors also and had those same motor problems ! NO CONNECTORS BETWEEN ESC AND MOTOR !!!

I though it is not necessary, because older KK board was ok.... but I cant solder anything anyways, If I cut it wont be enough length... waiting for shipment of wires.

Hey what kv motors are you using ? The timing comes set at low on default settings on the skywalker ! If your using higher than 1200 kv motors you might need to set timing on skywalkers at medium ! Timing can also cause motor problems ! I am running 1200kv motors and they are running on low timing and perform great !

1000kv, I believe I set it to low, it was medium, i think I was playing with settings before