Motors twitching in flight

John Arne Birkeland March 10, 2013 at 6:39am

To check if you need the latest PPM encoder there is a new RC Jitter test in the source repository.

https://github.com/diydrones/ardupilot/tree/master/libraries/AP_HAL...

Either compile and upload it yourself using Arduino 1.0.3 (Autopilot version) or use on of the pre-compiled files that I have included here, and upload using the "Load custom firmware" option in the Mission Planner.

The jitter test is a APM application, not a PPM encoder firmware. Do NOT try and upload it to the PPM encoder chip using the DFU bootloader.

After a successful upload, connect to the APM board using the Mission Planner Terminal window (CLI) and let the test run for about 30min. Make sure you do not touch the R/C radio while doing the test.

After a while your test should look something like this.

< 00:08:24> -------------------------------------------
ch1: center:1520 min:1516 max:1522 delta:4
ch2: center:1542 min:1539 max:1545 delta:3
ch3: center:1934 min:1930 max:1936 delta:4
ch4: center:1520 min:1516 max:1522 delta:4
ch5: center:1851 min:1849 max:1854 delta:3
ch6: center:1520 min:1517 max:1522 delta:3
ch7: center:1521 min:1519 max:1523 delta:2
ch8: center:2074 min:2069 max:2076 delta:5

If no channel show delta changes above 10, you do not need to upgrade the PPM encoder. If they are much higher (and you are sure you did not touch any of the sticks during the test), you definitively need to update to the latest version (V2.3.16).

Also, you have problems with jitter delta greater then 10, please send me a PM with some details about your radio setup.

RCJitterTest_APM2.x.hex

RCJitterTest_APM1.x.hex

Daryl February 2, 2013 at 10:47am

I have a question for the group and this may be unrelated to this latest upgrade, but since I flashed the AdruPM v2.3.13 fw, I cannot seem to get channel 6 to tune my PID terms. The APM recognizes channel 6 with a range from 1101 to 1941, but when I set up CH6 to a P term with min=0 to max=3, I note while refreshing the config screen for each turning of the radio dial it remains at the min value until CH6 reaches somewhere between 1353 and 1381 where it then jumps to the max value. I am not getting a linear setting in between the min and max.

Has anyone else experienced this problem or tried the CH6 tuning options since they flashed in the new fw?

avionics February 2, 2013 at 3:58am

after updating i tested and it works fine no more twitch. well done.

Daryl February 1, 2013 at 6:30pm

Now that there is a solution for the Futaba receivers, is this firmware compatible with other receivers or does a person need to flash the other version? If it’s compatible across the board, can we assume future shipments of the APM will have the new release in it?

P.S. Thanks to the OP for starting this thread, it was a big help and great resource.

Daryl January 28, 2013 at 6:26pm

I've been beating my head against the wall all weekend wondering why I was getting this twitching or glitching issue. I was trying everything from isolating the APM via various sizes of foam to the frame, filtering, tuning, fresh batteries, logging and analyzing, and getting to the point of developing a love hate relationship with this thing. Late last night after numerous searches, I came across this thread and thinking this has got to be it. Eager to try this new firmware, today I took the APM 2.5+ out of the xcopter, opened the case to expose the board and flashed in the new firmware. Sadly, I have no time tonight to test it, but when I do, I will post up. In the meantime, here is a compilation of videos showing the twitching during my futile attempts on the weekend to resolve this issue. The big one is at 52 seconds and after that, it was like "f*&%k it", this thing is coming out.

https://www.youtube.com/watch?v=8PxUfscup2s

Incidently, I am using a Futaba 2.4GHz FASST radio/receiver combo with the receiver being a R6014HS 14-channel receiver.

Mike Boland January 16, 2013 at 9:44pm

This thread seems to have gone quiet without any news of a fix for us APM1.4 users who also use Futaba.

Has there, is there, will there, be any fix for the PPM encoder on the 1.4 boards?

Developer

Marco Robustini December 27, 2012 at 1:23am

Hi Oliver, with your latest ArduPPM this problem has been resolved, after many flights have established two quad that I have no more "kick", thank you!
You should open a discussion advising all users with Futaba tx to perform this update on APM2/2.5.

Bests, Marco

Søren Kuula December 23, 2012 at 1:53am

Hi,

One great way to overcome problems with PWM to PPM (back-)conversion is not to use it.

I can recommend the FrSky TFR4 receiver for FASST. It is small, inexpensive, works with 7CH and "multi" as well, it has a direct PPM output with 8 channels, it has diversity and it has an RSSI output.

It will also rid you of half a dozen servo jumper cables :)

Regards

Soren

Mike Boland December 16, 2012 at 7:46pm

I am trying to load the new PPM encoder into a couple of V1.4 boards I have and have run into a couple of problems.

Following the Wiki instructions:

Using the the AVR ISP Mk2 I first tried downloading the latest AVR Studio 6, unfortunately the stk500 is no longer an exe but an xml file??

So I tried downloading AVR 4.19 and all went well up to the reading of the FLASH input file where I get the error "could not read FLASH input file firmware.hex" and the procedure aborts.

I had downloaded the latest ArduPPM_v2.3.13_ATMega32U2.hex placed it in the folder with firmware_arduino_328_16mhz.bat and renamed it firmware.hex.

Am I missing something here?

Any help would appreciated.

Mike

avionics December 16, 2012 at 11:49am

Excellent work any chance we get an explanation as how you solved this problem.

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Motors twitching in flight

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