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2DOF with wheelchair motors

Discussion in 'DIY Motion Simulator Projects' started by Bernd Manger, Jan 8, 2016.

  1. Bernd Manger

    Bernd Manger Active Member

    Joined:
    Oct 6, 2015
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    156
    Occupation:
    Measurement and control mechanic
    Location:
    Germany
    Balance:
    962Coins
    Ratings:
    +254 / 12 / -0
    My Motion Simulator:
    2DOF, DC motor, Arduino
    Thanks, @speedy
    I will soon take videos of the sim and shifter.
    • Like Like x 2
  2. auryza

    auryza Active Member

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    My Motion Simulator:
    2DOF, 3DOF, Arduino
    Do not be so modest ! What we see you are great programer !
  3. Bernd Manger

    Bernd Manger Active Member

    Joined:
    Oct 6, 2015
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    Occupation:
    Measurement and control mechanic
    Location:
    Germany
    Balance:
    962Coins
    Ratings:
    +254 / 12 / -0
    My Motion Simulator:
    2DOF, DC motor, Arduino
    I was asked to post the Arduino and Processing3 files from my post:
    https://www.xsimulator.net/community/threads/2dof-with-wheelchair-motors.7905/page-2#post-125188

    Meant just for the sake of interest.

    At this moment these codes are NOT meant for members without Arduino- and Processing- programing skills.
    They are written to meet my hardware requirements. (2 motors with quadrature encoders, bluetooth interface, Sabertooth 2x32)

    About SMC3 and Quadrature encoders:
    In my opinion it's not possible without big changes. The SMC3-code reads the analog inputs(feedback pots) and calculates PIDs about 4000 times per second. So it's too busy to do deal also with encoders. But this high rate is not necessary. The values from SimTools come only 100 times per second(every 10msec).
    So i've decided to do PID calculations(now with floating point numbers for a better resolution) 125 times per second(every 8 msec). So there is enough time for the encoders and serial transmissions.
    Quadrature encoding needs a lot of Ard. performance. (max frequency is about 100kHz)
    For example:
    A motor with 3600 rpm and encoders(with 500 pulses per turn) mounted on the motor shaft = 30kHz count frequency.

    Because i needed other adjustment possibilities, but having no access to the SCM3Utilities-code, i've decided to write my own GUI with Processing3.

    Here is an overview:
    SMC_S.png
    Processing is used to set the PID parameters and watch the movements of the sim.
    But it is unhandy to work with an extra PC to do this.
    The good news:
    Because Processing is based on Java, it has an Android mode to write Apps.
    My goal is to transfer the Processing sketch to an App running on a tablet.

    For those members who do not know Processing:
    It is a sister project to Arduino and meant for all kinds of visualsations.
    It's also open source, has a simular gui, almost the same syntax and as many libraries available as Arduino.
    But it's based on Java, in contrast to the arduino code, based on C++.
    Arduino and Processing are a perfect combination.

    Attached Files:

    • Like Like x 3
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  4. auryza

    auryza Active Member

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    Location:
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    4,125Coins
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    +70 / 0 / -0
    My Motion Simulator:
    2DOF, 3DOF, Arduino
    Hi @Bernd Manger @
    I have everything what i need, except rotary encoders, i'm still waiting for them to arrive. Definitely will try this kind of setup. But what i see above in this thread , gonna be a lot of questions. ;)
  5. Bernd Manger

    Bernd Manger Active Member

    Joined:
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    Occupation:
    Measurement and control mechanic
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    Germany
    Balance:
    962Coins
    Ratings:
    +254 / 12 / -0
    My Motion Simulator:
    2DOF, DC motor, Arduino
    Here are 3 videos about Arduino & quadrature encoding:



    • Informative Informative x 4
  6. bergstein

    bergstein New Member

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    My Motion Simulator:
    Arduino
    Thanks for sharing the experience
  7. Tomsix

    Tomsix Member

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    My Motion Simulator:
    Arduino

    Hi

    Hi, i work on my own sim 2dof with Wheelchair motors. I have no motor brakes on it and have a big problem with the backdrive. How do you avoid the backdrive effect if the motors are not powered.
    Any ideas welcome
  8. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator

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    Innovative tech specialist for NGOs
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    My Motion Simulator:
    3DOF, DC motor, JRK
    The easiest approach is to make some locking chocks for when the rig is un-powered, and pivot them out of the way when you want to use it.