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Question Motors informations (RPM, ration, Nm) for a beginner

Discussion in 'New users start here - FAQ' started by alenig, Feb 15, 2017.

  1. alenig

    alenig New Member

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    Hello, :sos

    first of all I introduce myself, my name is Alessandro and I'm from Italy. I just decided to start with my first DIY 2 dof simulator project.
    After reading many and many threads regarding the possible system to adopt, I choice to use 2 Pololu Jrk 12v12 with 2 motors behind my seat.

    Now it's time for an hard choice: which motor should I use (good quality/price)?

    I would like to say that I am not an expert in mechanics so it is difficult for me to understand all the aspect to take into account during the motor choice. For this reason I decided to open this thread, so I will ask some questions:

    1) Some of you have already found good motors (in terms of quality and price)? It have to be accessible also from Italy.
    2) Could someone help me to understand the technical aspect of RPM, ratio and Nm?
    3) How can calculate the RPM, the ration and the Nm that I need for my 2 dof simulator?

    I take the opportunity to say sorry for my not perfect english :grin:grin:grin
    • Like Like x 1
  2. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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  3. alenig

    alenig New Member

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    Thank you very much for your quick reply.
    Due my english, I'm not sure that I well understood the meaning of CTC lever. Is it the metal bracket builded to connect the motor to che arm?
  4. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    Yes you got it, he CTC is the Center To Center distance on the lever from the shaft center to the hole in it where the arm connects.
  5. alenig

    alenig New Member

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    If I consider the characteristics here below, is there someone that have some advise for me (both in high or lower value)?

    12v DC, 180W, 50:1 gearbox ratio, 20N.m, 80 RPM output speed

    Thank you in advance!!
  6. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    Motor choice depends on the design but those would work for a lot of them.
  7. obobo

    obobo Active Member

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    for 2DOF, it's good

    for 3DOF, with 3 motors it's small

    for 3DOF with 4 motors, its good
  8. Pit

    Pit - - - - - - - - - - - - - - - - Gold Contributor

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    From the technical viewpoint I really doubt you will get a 3 DOF working with 180W motors, especially if we have monitors, OSW or other gadgets attached to the rig.
  9. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    You would need some form of heave assist, but monitors would kill it.
    • Agree Agree x 1
  10. obobo

    obobo Active Member

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    a 3DOF roll pitch heave seat mover !!
  11. Pit

    Pit - - - - - - - - - - - - - - - - Gold Contributor

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    As @noorbeast mentioned you need a heave assist f.eg. in form of a spring or gas strut
  12. mirkobastianini

    mirkobastianini Active Member

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    Ciao Alessandro, da Roma!

    Hi Alessandro, from Rome! I'm in the same situation, I want to build a 2DOF compact, with motor under the seat. The best thing that you can do to start, is to build a small RC model to understand all of theory behind simulation and you can be confident with simtools (the software for the simulator).

    You can easily build it with Arduino and 2 RC motors.

    Here you can see my little model in action:


    After that you can think about simulator .. if you want to put motors under seat you need 50:1 or 60:1, and if you want to use JRK you must stay under 16/20A load. Other parameters are not very important, except speed (70-80 RPM is good).

    Anyway, why you want to put motors on back? If I can give you advice, I would suggest to put motors on front under the seat, so the sensations of corners are more realistic (build little model and you can see this thing).