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Thread: Project

  1. Project

    Hi Everyone!

    Just wanted to showcase a project we (a couple of students from University of Applied Sciences Bielefeld) are currently working on. It is a continuous-track robot that is able to deform itself to a certain extent and thus, able to overcome obstacles or uneven terrain. The robot basically is built from out-of-the-box AX12-A servo drives with some 3-d printed encasings, which mainly exist to have something to place the sensors/boards on.

    I´ll let the video speak for itself and if there are any questions, let me know and i´ll try to do my best to answer all of them:



    If you´re interested in the mathemathics that run behind this, you can also take a look at the corresponding IEEE paper:

    http://ieeexplore.ieee.org/xpl/artic...r%3A7487087%29


    Thanks a lot for your interest!

  2. #2

    Re: Project

    Now to put four of them on a buggy and drive around a rock field :-)
    Is the blinky red light on the side an OpenCM?

  3. Re: Project

    Hey,
    that´s actually a Teensy-board: (https://www.pjrc.com/teensy/teensy31.html)


    We use it to read the data from the a/d-converters and to communicate with a desktop computer that calculates the kinematics of the movement.

  4. #4
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    Re: Project

    Quote Originally Posted by jwatte View Post
    Now to put four of them on a buggy and drive around a rock field :-)
    In a vacuum...

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    Re: Project

    Nice video. Well done.

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    Re: Project

    Nice work. What sensors do you use?
    Kåre Halvorsen aka Zenta
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  7. Re: Project

    Quote Originally Posted by Zenta View Post
    Nice work. What sensors do you use?
    We basically have self printed flex-pcbs that we put on the outer side of the encasing. On top of that is just regular ESD-foam.

    The "sensors" are two comb-shaped electrodes, which in combination with a voltage-divider circuit detect ground contact by increasing the area of contact between the electrodes and the foam and therefore, changing the resistance on the circuit. Probably sounds more complicated than it actually is .

    See if these pictures help you understand, and if not, don´t hestitate to ask!:
    Click image for larger version. 

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  8. Re: Project

    Quote Originally Posted by jwatte View Post
    Now to put four of them on a buggy and drive around a rock field :-)
    Is the blinky red light on the side an OpenCM?
    Haha yeah, we´re imagining situations like that everyday in our lab.
    That blinking thing is a teensy! Really cool and compact development board. (https://www.pjrc.com/teensy/)
    We use it to communicate with a desktop computer to calculate the kinematics of the movement and to pass on the ouputs of the a/d-converters.

  9. #9

    Re: Project

    I love the Teensy! Do you make that talk to the Dynamixel bus as well, or is that some other interface?

    Also, the kinematics could conceivably actually run on the Teensy itself? It's a pretty capable board.

  10. Re: Project

    Quote Originally Posted by jwatte View Post
    I love the Teensy! Do you make that talk to the Dynamixel bus as well, or is that some other interface?

    Also, the kinematics could conceivably actually run on the Teensy itself? It's a pretty capable board.
    Not yet, but we´re currently working on an attachable pcb for the Teensy (or maybe with the teensy, not sure about that yet) with some additional circuitry to make the full duplex UART on the Teensy board able to talk to the Dynamixel drives (which run half-duplex).

    We haven´t been doing any calculation-stuff on the teensy yet, but I think especially the inverse kinematics are rather heavy on the processor (plus, for now we´re checking every iteration to avoid any crazy/weird tension in the robot since the ax-12a drives are not the most sturdy ones) and we´re aiming at a high frequency for now. But obviously that could be one of the next logical steps, and is something we´ll be definitely looking into.

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