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Start a 3DOF with DC motors

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by alejandro2lanz, Jan 17, 2021.

  1. alejandro2lanz

    alejandro2lanz Lanz

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    My Motion Simulator:
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    Hello, I want to start a 3DOF project, and the more I read in the forum, the more doubts I have.
    For which I would like some advice.
    First of all I want to use DC motors, because of budget.
    After much searching I had decided on these:

    https://es.made-in-china.com/co_mei...DC-Motor-80mm-24V-3000rpm-400W_ruiiyyrig.html

    But the manufacturer recommends motors with the same brushless specifications (BLDC).
    Here my first question, they are a little more expensive, but is it worth the (BLDC)?
    Are these motors compatible with SMC3, and with the H bridges, mentioned below?
    I want to use the heave without springs, the motors are 57Nm, could they handle my weight and the colpick? about 120 Kg approximately


    About potentiometers I was thinking of Farnell's hall sensors, but at home I have two precision Spectrols, from an old project.
    Are good ?

    81291

    As it is necessary to assume expenses of motors potentiometros and source.
    In principle I'm going to start with Arduino UNO R3, SMC3 RufusDufus, cheap 43A IBT-2 H bridges.
    Is there a better PID than SMC3?

    And this is where I have more debts,
    In the short term I want to improve the simulator.
    I continue with arduino with good H points, like the Sabertooth?
    Is there much difference from one bridge to another?


    I happened to pololu?
    If so, what pololu plate options do I have, for motors that are over 20A?
    Pololu worth it?

    Or some other option?
    Thanks in advance
  2. Ads Master

    Ads Master

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  3. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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    It is hard to judge if a motor is adequate or not without knowing all aspects of the design and load. Alternatively you can look for similar successful member project and compare specifications.

    Personally I prefer Hall Sensors, they are very accurate, robust with a long life span, and won't break if over rotated.

    There is alternate code options to SMC3, depending on hardware choices, see the FAQs: https://www.xsimulator.net/community/faq/arduino.6/category

    But SMC3 is popular because it has the Utility application, which makes configuration much easier.

    Similarly, there are potential hardware choices, see the FAQs: https://www.xsimulator.net/community/faq/motor-drivers.11/category

    IBTs are a budget option but if your plans are long term refinement then Sabertooth may be the way to go, as they are very robust with good manufacturer support.
  4. alejandro2lanz

    alejandro2lanz Lanz

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    I forgot something,
    What type of gearbox is better, or should I reuse?: Worm gearboxes, helical, planetary,
    At first, the engine I was planning to buy comes with an RV40 or 60.
    Is it good?

    About the mounting of the potentiometers, or hall sensors:
    What gear ratio should I use? 1/1 with the same speed as the engine?, Or reduced, and at what ratio?
    Or is it the same?
  5. Sam Neall

    Sam Neall Member

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    My Motion Simulator:
    2DOF, DC motor, Arduino, Motion platform
    It is best to use a 1/1 ratio for reading on pots with >360 degrees rotation. When researching a motor, look at torque and rpm. The gearbox is only half of the equation. The motor itself needs to have sufficient torque and speed. In my opinion, more than 60 rpm is fine and the torque depends on your rig.
  6. alejandro2lanz

    alejandro2lanz Lanz

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    My Motion Simulator:
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    I continue with the project, I have already bought the engines, total 4.
    three for the 3dof and one for the loss of traction.
    The reference: 80zyt165 80mm 24V 440W 60: 1

    As they have double shaft I suppose I don't need a cardan joint for the colpick?
    Won't they do the yaw thing?
    Or if ?

    Over the bridges I will pass directly to the Sabertooth 2x32A.
    For europe where are they cheaper?

    About the power supply, that you advise me.
    4 of 600W, two in parallel for each bridge?
    Or two 1200W one per bridge?
    Or more? , or less power?

    On arduino I want to use SMC3, the questions are if I buy the UNO or the MEGA?
    I will have to use two cards.
    Connect two motors per card? Or three in one and the loss of traction in the other.

    In some posts I have seen that they connect some orange boxes to the Sabertooth bridges. Are they clamp resistors?
    If so, are they necessary? Which ones should I buy?
  7. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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    As mentioned in my earlier post, the adequacy of motors are influenced by design of the rig, in particular how much inherent design leverage is used.

    A traditional 3DOF does not use a cardan, but some 3DOF rigs still use them for particular design reasons, so I do on my compact 3DOF, as I use adjustable spring assist, which in turn lets me use smaller motors: https://www.xsimulator.net/community/threads/dx-compact-simulator.5866/page-15#post-83752

    @prilad has an innovative design that combines what would be a 3DOF but allows traction loss: https://www.xsimulator.net/community/threads/prilads-4dof-dc-motor-sim-rig.6157/

    SMC3 is coded for the UNO and yes you use 2 motors per Arduino with @BlazinH's modified SMC3 code: https://www.xsimulator.net/communit...ket-serial-pid-motor-driver-for-arduino.9277/

    I believe @Rens used those motors and a single 1500w PSU for his compact 6DOF, so likely is in a better position to give advice on motor capacity and PSU load.

    I am not in Europe but suspect Sabertooth are likely comparative in price.
  8. alejandro2lanz

    alejandro2lanz Lanz

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    My Motion Simulator:
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    Thank you very much Noorbeast.
    I am inspired by this.
    https://www.xsimulator.net/communit...lator-building-tutorial-3dof-heave-axis.9249/

    Although I will put a lever longer than 70mm
    , with several holes for the connecting rod.
    Which will allow me to use the appropriate lever length for the deck design.

    I have already studied your wonderful project, and you deserve a good compliment
    But in my case, I have a lot of space, and I'm going to do things the other way around.
    I'm going to start the house from the roof.
    I will first do the upper part of the chair with the steering wheel and pedals.
    I'll keep going down with the cranks, giving it 14 degrees of openness.
    And from there the measurement of the base will result