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Thread: How can avoid the jerking of 6-DOF arm made up of AX-12

  1. #11
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    Re: How can avoid the jerking of 6-DOF arm made up of AX-12

    I think they're referring to using servo speed to control an entire large movement. Say from foot on the ground to foot up in the air with no interpolation.

    My code runs at 50hz and calculates the position IK at every frame. It does use the default servo move speed though. In order for perfectly smooth motion those, the servo speed should change depending on the distance traveled for the set frame rate. I believe default is full speed, which may be too fast for a short distance and might introduce some jitter since it may arrive too soon and have to wait. It probably overshoots its position a bit as well.

    I'm picturing real-time position and velocity IK at 30-50hz. The servos should move to the correct position at the correct speed for every frame. Ideally that would be pretty smooth

  2. #12

    Re: How can avoid the jerking of 6-DOF arm made up of AX-12

    If you send IK updates at 50 Hz, and you're getting a lot of jitter, then your problem is much more likely that the servos aren't strong enough, and/or the build is not rigid enough, for what you're trying to do.

    Post video, and perhaps a drawing of the different linkages/lengths, and someone might be able to help better.

  3. #13
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    Re: How can avoid the jerking of 6-DOF arm made up of AX-12

    No, I'd say my robot is pretty smooth. But things can always be better. If i were to calculate the proper move speeds i could probably dial back the frame rate to like 30hz and possibly end up being even smoother.

    We're learning about inverse velocity kinematics now in class so i may try to roll this into our class project since its relevant.

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