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Author Topic: Problem with dynamixel ax-18a and axon II in the feedback  (Read 1295 times)

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Offline Ricardo GómezTopic starter

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Greetings, I have an axonII and a Dynamixel ax18a, I am using interface indicated by webbotlib and using version 2.09 webotlib, I already set the ID in each servomotor. Position the servomotors with
 ax12_set_GOAL_POSITION(&_servo_, X);
 and
servo.setSpeed(X);
functions perfectly.

The configurations are generated WebbotLib dynaixel Project Designer with 1M in theUART0. The problem is that when I try to feedback to the command servo.dumpAll() or servo.read() throws me the error 0x400 "we received an invalid header". Any ideas or help?
« Last Edit: May 31, 2012, 05:57:42 PM by Ricardo Gómez »

Offline Gertlex

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Re: Problem with dynamixel ax-18a and axon II in the feedback
« Reply #1 on: May 31, 2012, 06:11:50 PM »
I've used the AX-12 (identical to the AX-18 in software of course) successfully with Webbotlib 2.0x.  I've been using C, rather than C++ though; I think you're using C++?

I can successfully do
Code: [Select]
ax12DumpAll(&UART3toAX12_driver);Which is for all of my servos... but I'm not sure I've ever done data fetching from single servos.

I don't want to make you redo your code in C, if possible... I'm sure Webbot will have better ideas :)
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Offline Webbot

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Re: Problem with dynamixel ax-18a and axon II in the feedback
« Reply #2 on: June 01, 2012, 06:41:20 PM »
Haven't tried, or got, th ax18a. But I guess it should work ok.
The dumpAll command Gertlex mentions just does a read/dump of each servo in turn.
Only thing I can suggest is try a lower baud rate. Also try with just one servo connected - to make sure you've got your wiring correct
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Offline Gertlex

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Re: Problem with dynamixel ax-18a and axon II in the feedback
« Reply #3 on: June 02, 2012, 03:39:28 PM »
Oohh, and idea that just occurred is to double check that the tristate buffer is working/hooked up right?  Make sure the signal wire is connected too... I had mine wired to the wrong pin for a few months and so it just floated.  Most of the time I could send commands to the servos, but it was flaky... and getting info back just didn't work, if I recall correctly.
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Offline Ricardo GómezTopic starter

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Re: Problem with dynamixel ax-18a and axon II in the feedback
« Reply #4 on: June 04, 2012, 07:47:37 AM »
Thanks for your support. the problem was with the source, I was using a laboratory power supply and replace it with a lipo battery I worked right all ...

Offline Gertlex

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Re: Problem with dynamixel ax-18a and axon II in the feedback
« Reply #5 on: June 04, 2012, 06:00:00 PM »
Good to hear... they take a lot of current, aye.  Make sure to get a battery monitor, e.g. these.
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Offline Ricardo GómezTopic starter

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Re: Problem with dynamixel ax-18a and axon II in the feedback
« Reply #6 on: June 05, 2012, 07:34:17 AM »
ok you're right! the problem was that the source was generating a magnetic field that corrupted packets
« Last Edit: June 05, 2012, 07:53:03 AM by Ricardo Gómez »

Offline Admin

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Re: Problem with dynamixel ax-18a and axon II in the feedback
« Reply #7 on: June 05, 2012, 08:03:27 AM »
ok you're right! the problem was that the source was generating a magnetic field that corrupted packets
wha?

Offline Ricardo GómezTopic starter

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Re: Problem with dynamixel ax-18a and axon II in the feedback
« Reply #8 on: June 05, 2012, 03:00:42 PM »
the power supply generated a magnetic field that corrupted packets

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Re: Problem with dynamixel ax-18a and axon II in the feedback
« Reply #9 on: June 06, 2012, 08:54:54 AM »
the power supply generated a magnetic field that corrupted packets
How'd you determine that? Are you sure it wasn't noise, or insufficient current? (if a power supply can't supply enough current, the voltage drops, and that would interfere with binary)

Offline Gertlex

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Re: Problem with dynamixel ax-18a and axon II in the feedback
« Reply #10 on: June 06, 2012, 09:32:38 AM »
Not that we're diagnosing something right now, but out of curiosity, what was the Axon II's power supply?
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