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Thread: Servos resetting IDs?

  1. #21
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    Re: Servos resetting IDs?

    If you have any servos that have duplicate IDs, everything will fail. Please verify none of your servos have the same ID before proceeding. This may entail hooking each one up individually and using the Pypose terminal to verify/reset if you do not own a USB2Dynamixel.

  2. #22
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    Re: Servos resetting IDs?

    9 should give you something. Usually a position of -1 will be reported for the servo IDs that have been reset. You are getting -0.1 back due to the same issue. Un-hook the leg that has servo with the ID:1 and try again.
    Last edited by KevinO; 05-29-2013 at 11:26 PM.

  3. #23

    Re: Servos resetting IDs?

    I also have sufered id resets, even around 16 AX-12 recently, using my own software and connected to SMPS, so I suspect that some wrong but valid sequence could be the cause.

  4. #24
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    Re: Servos resetting IDs?

    Thanks for the support guys, things are starting to make sense. I was getting a little nervous there.

    I didn't have a chance to work on it yesterday, but i will today.

    I plan to use the 12V 5A from Trossen (came with my kit for the battery charger) to power the bot on the bench. Is 5A enough to ensure i don't brown-out? From what I've been reading I'm thinking it might not be enough. I'll probably need to find a beefy adjustable benchtop supply so i can supply more juice and also adjust to 11.1V to better reflect application. Then again if the legs are floating in the air and I don't do anything stupid in my code, the servos shouldn't stall.

  5. #25

    Re: Servos resetting IDs?

    It will be interesting to get a definitive answer to the resets. As it has been suggested, it could be a low power situation, but I wonder as the code I run on the Phantom checks the power and shuts off the servos if the voltage gets below some threshold. Note: this code I believe is disabled in the PhantomX_AX12_Stock project as when I started adapting the Phoenix code to run on the PhantomX, I was finding the communications to the AX12 to be unreliable for this, so instead I wired up a resister divider circuit up from the battery to one of the Analog IO pins, which not only was more reliable but less overhead.

    Later I figured out what was going on with the AX12 communications, to clobber the data and wrote my own version of the library to fix it. The issue was fixed a different way in the main code base. As a side effect, these fixes significantly reduced the number of times my servo IDs were reset.

    The code is still in place to ask the servos for the voltage. That code originally always asked servo ID #1 for it's voltage. I believe some others have modified it to maybe ask different servos for it. Potentially ones that have more stress put on them. I don't remember if they cycle through multiple servos or always ask the same one.

    Kurt

  6. #26
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    Re: Servos resetting IDs?

    Kurt, to clarify, i wasn't running your Phoenix code during any of this. When my lipos dipped low, i was running the "stock" Nuke code provided on the Trossen website. During the debugging effort I've only run the "stock" Nuke code, my code, and your AX12_Test code.

  7. #27

    Re: Servos resetting IDs?

    Understood,

    Personally I have doubts that this is a low voltage issue. That is I am assuming you are running a 3s lipo and probably worst case you ran it down to 10v? It is my understanding that the default Bioloid Comprehensive Kit ships with a 9.6v NIMH battery. So I doubt you got that low. My assumption is also that the battery has a VR in it that runs the electronics at a considerably lower voltage... Could be wrong. But AX-12 manual says 7-10v, likewise DFRobot makes an serial interface adapter for AX like servos (http://www.robotshop.com/productinfo...142&lang=en-US) and they also say the input voltage should be between 7-16v (obviously for these I would not go that high!)

    Not sure which version of the AX12 code you are running, but assume that you have linuxfergy's fix in it. My version is quite a bit different in that I don't use an interrupt for the RX, but instead read it in as it comes in. Also the main fix was to instead of try to guess how long I need to wait before switching between TX and RX mode, I instead I setup and wait for the TX complete flag before I switch modes. Also on general principle as I have been bit on other processors, I made the bit changing code be interrupt safe... I have posted this code up here before and can again if anyone want's to take a look at it.

    Kurt

  8. #28
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    Re: Servos resetting IDs?

    Kurt,

    I'm using your tool now and have identified the culprit. My problem earlier was that had the Serial Monitor set to
    'no line ending'. When i set it to return with a CR, the menu responds to my commands.

    After unplugging the real #1 and using the position listing i've found that my #10 servo has reset to #1. The voltage also looks correct.

    My problem now is that when i enter command 8 to "Set ID: <old> <new>" i can't get the prompt to appear. I see in the code that it should ask me to enter the old and new servo IDs. Whenever i enter 8 to run the command, the menu just appears again. I tried entering "8 1 10" as well but no luck. Any ideas?

  9. #29

    Re: Servos resetting IDs?

    FWIW: A 5A supply is not enough for transients such as start-up, enabling servos, etc, for my bot (with bigger current draw servos.) When I parallel my benchtop supply to 10A, it's still not enough for the initial power-on draw, but it's okay for movement with legs hanging in the air.
    Typically, I keep the battery connected, and add power with the benchtop; the battery supplies current when the benchtop sags. This keeps the battery at a fixed voltage, which is not great for long-term lifetime, but I keep it below max voltage so it's not been bad so far. For a 4S battery, max charge is 16.8V, nominal voltage is 14.8V, I keep it at about 15.3V. When I was running 3S, max was 12.6V, nominal was 11.1V, I kept it at 11.5V. If you really care about the "no trickle charging" advise, you can add a large current diode from the battery to the power supply connection point, so the battery will kick in once voltage sags enough, but won't be kept at voltage when there's no load.

  10. #30
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    Re: Servos resetting IDs?

    ^That's a good idea to run both sources in parallel, interesting.

    Its fixed! I installed pypose and used the Terminal to change the servo ID. It worked like a champ and now i'm off and running. And i'm super pumped because my latest bug fix worked and now my IK works perfectly for body translations and rotations! Baby steps to you guys, but quite an achievement for me. Thanks for all your help!

    Now onto moving these feet...

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