Arm goes automatically down2018-11-18T16:34:26+00:00

Forums Niryo One Troubleshooting Arm goes automatically down

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  • Author
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  • wodcleaner
    Participant
    Post count: 17

    Hi There ,

    i am still wondering if it is correct that my Arm goes down automatically because of that large spring in the shoulder. But only when it is powered down.

    A Video

    BManCan
    Participant
    Post count: 22

    I have been wondering the same thing with my new Niryo One Robot. In some videos (see  link ) it looks like the robot should be able to hold up its own weight better on axis 2, but mine also drops like in your video.

    • This reply was modified 3 weeks ago by  BManCan.
    duck
    Participant
    Post count: 39

    @wodcleaner and @bmancan

    I am wondering if the problems that you are experiencing are related to something happening with the torsion spring inside Axis 2 (the Shoulder) becoming unseated from it’s mount in the Arm Bottom.

    I was surprised at the strength of the torsion spring during the assembly of the v2.0 robot. It may have to do with the differences in the assembly procedure compared to v1.x, but I am wondering if I the torsion spring in the v1.x robot that I have is having some issues. Neither of the robots that I have is behaving as extremely as what @wodcleaner shows in his video; I really do suspect that what he is seeing is a fully unseated torsion spring.

    It would probably be best to see what Edouard and others from Niryo might advise, but it might be worthwhile for you to disassemble the Shoulder to check whether the torsion spring is still seated properly.

    I have had some experience disassembling the Shoulder. It is somewhat difficult to accomplish. You need to use a regular screwdriver and a putty knife to carefully coax the torsion spring out of it’s sockets in order to get the Arm out of the Shoulder.

    By the way, @wodcleaner, I really love the color scheme on your self-printed robot and look forward to seeing it in action soon. @BManCan: have you been able to get your robot to calibrate?

    BManCan
    Participant
    Post count: 22

    I decided to disassemble the shoulder to check on the torsion spring. I could not determine if the spring was unseated, but now that it is reassembled it appears to be holding position better when powered down (assuming the shoulder and elbow are near calibration position).

    @duck: I have not really had any issues with calibration. I usually use the manual calibration.

    • This reply was modified 3 weeks ago by  BManCan.
    duck
    Participant
    Post count: 39

    @bmancan

    I guess I am used to doing automatic calibrations periodically since with the older software the manual calibration method didn’t work as reliably.

    Do you have a v1.x robot with a stepper on Axis 4 or a v2.0 robot with a Dynamixel XL-430 on Axis like @wodcleaner?

    I assume that your robot is able to complete automatic calibration successfully. How is it behaving otherwise? Any problems or is it working as expected?

    wodcleaner
    Participant
    Post count: 17

    I disassemble the shoulder later this day to check the torsion Spring. Maybe i‘ve put it upside down.
    That would at least explain why the arm goes down and does not stand still at the top.

     

    @Duck

    when you push down the arm, does it straighten up again?

    • This reply was modified 2 weeks, 6 days ago by  wodcleaner.
    • This reply was modified 2 weeks, 6 days ago by  wodcleaner.
    • This reply was modified 2 weeks, 6 days ago by  wodcleaner.
    • This reply was modified 2 weeks, 6 days ago by  wodcleaner.
    wodcleaner
    Participant
    Post count: 17

    Update : in the Bottom Arm the inner Ring  was Brocken, where the spring is.

    Edouard Renard
    Keymaster
    Post count: 122

    Hi everyone,

    The fact that the axis 2 is going forward (when motor is not running) is not an issue. It sometimes happens, due to the strength of the torsion spring.

    @wodcleaner if you’re able to use the robot now with your configuration, then I can assure you the torsion spring is not upside down (any way you’d have much trouble to assemble it upside down because it simply won’t fit).

    This is an improvement we are currently working on, so in the future we might be able to put all the torsion springs with the exact same configuration. (which is not an easy thing)

     

    duck
    Participant
    Post count: 39

    @wodcleaner

    To answer your question above, no, the arm does not straighten on its own on either of my robots. The weight of the full arm when assembled seems to counteract the torsion spring. I did experience the kind of behavior to which I believe you are referring in regards to the Shoulder assembly after completing Step 2 of the v2.0 robot assembly (before the Elbow and all the parts of the Arm where attached in Step 5).

    You mentioned that you found something broken when you disassembled the Shoulder. Was the 3D-printed Arm Top broken inside where the torsion spring attaches? That would probably make the torsion spring float freely inside and explain the behavior you were experiencing.

    Would you please post a photograph showing what was broken? I am just interested in what was causing the problem. This would probably be of use to others on the forum in diagnosing problems that might occur with their robots.

    wodcleaner
    Participant
    Post count: 17

    The torsion spring presses laterally against the inner ring during movements, so it is probably broken off and the spring has shifted.

    I printed this part from PLA with 20% Infill, which seems to be too little. the next one gets 40% Infill.

    Video of broken Part

     

    greetings from Germany,

    Christopher

    duck
    Participant
    Post count: 39

    Thank you for posting the video showing how the Arm Bottom broke.

    I don’t know if it is helpful, but the Arm Bottom that I received from Niryo in my v2.0 kit weighed 85g. I suppose different filaments might have different weight and other properties but maybe that can serve as a reference point for the parts that you are printing.

    I hope that the 40% fill part holds up better.

    One more question: how are you embedding YouTube videos in your posts? When I tried to paste the EMBED text from Youtube into my thread in the Showcase section, I got a security error. Niryo’s WordPress functionality doesn’t seem to like something in that text.

    wodcleaner
    Participant
    Post count: 17

    I just copied the „Share“ link of the Videos here

    duck
    Participant
    Post count: 39

    @wodcleaner

    Thank you very much for sharing how you included a YouTube video. I had been trying to copy and paste the EMBED code from YouTube into the Text tab of a post in Niryo’s forum, but I just tried as you suggested and got a video to appear within the post without getting any errors.

    I hope that you are making good progress on reprinting the Arm Bottom for your robot and look forward to seeing more posts about your robot in the near future.

    wodcleaner
    Participant
    Post count: 17

    short Update :

     

    I have mounted the robot with the newly printed part ( arm bottom ), but the arm still goes down by itself.

    The Torsion Spring is mounted correctly.

    Maybe the top part is just a few grams to heavy , cause I´ve printed all parts in a higher quality from PLA.

     

    duck
    Participant
    Post count: 39

    @wodcleaner

    Perhaps your idea about the weight of the upper pieces of the robot being greater than Niryo’s printed parts would explain why the arm drops so easily. As Edouard suggested in his reply above, maybe it’s not a critical issue so long as your robot is calibrating correctly and other issues aren’t occurring during normal movement.

    Did you weigh the Arm Bottoms that you have printed (both 20% and 40% infill) and compare them to the weight I reported? Perhaps that might give you an idea of the approximate potential weight difference of the parts above. I could list out the weights of the rest of the parts in my kit if that would be helpful.

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