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Showroom My 2 DoF Zero Weld Seat Mover

Discussion in 'DIY Motion Simulator Projects' started by PMK, Mar 25, 2020.

  1. PMK

    PMK New Member Gold Contributor

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    Hi all,
    I've finished bolting together the first prototype build of my 2 DoF seat mover. The design is inspired by the Next Level Motion V3 and DoF Reality M2 seat movers.

    I'm using:
    2x - 12V 200W Motion Dynamics Motors with 25:1 Gearboxes
    (https://www.motiondynamics.com.au/worm-drive-motor-12v-24v-200w-180-rpm-20nm-torque.html)

    2x - JRK 12v12 Motor Driver Boards
    (https://core-electronics.com.au/pololu-jrk-12v12-usb-motor-controller-with-feedback.html)

    1x - 650W Seasonic Modular Power supply
    (This will be upgraded to a 1000W dedicated 12V LED PSU)

    2x - 300 degree pots
    (https://www.jaycar.com.au/10k-ohm-linear-b-single-gang-24mm-potentiometer/p/RP3510)

    1x - DIY universal joint made with 4 rod ends
    (To be upgraded to a motorbike driveshaft universal joint)

    90704113_2587135588223687_4783826327671144448_n.jpg

    This is my prototype power circuit
    90480472_514447909499715_5732409231252914176_n.jpg
    As I'm using the modular power supply and can only use 3 12V lines per motor I have had to limit the max current on the JRK's to 20A as each pin of a 12V line is rated for 7A. I've ordered a 1000W 84A 12V power supply to replace the current PSU.

    I'm currently running the whole setup with 25mm CTC levers and getting some really aggressive and pretty detailed motion out of the setup.

    Simcalc gives the following outputs:
    upload_2020-3-25_9-56-57.png
    With a linear speed of 392.7mm/s

    My JRK's are cooled with 2 heat sinks attached with thermal adhesive, one onto of the main chip and one on the underside of the board. With the single 120mm fan, the boards only just warm up after running Dirt Rally 2 for an hour.
    90442243_215351709878169_1259273459020595200_n.jpg
    The motors definitely require some better cooling as they get very warm to touch after play, probably around 50 degrees.
    I've attached the STEP and STL files I designed for the JRK mounts.

    To improve the resolution of the pots I've used a 2:1 gear ratio to get some more detailed control from them/address the play in the gearboxes.
    91280156_249360492766705_4182872446325489664_n.jpg

    Here's a video of the rig in action:


    Moving Forward
    Now that I'm happy with the basic motion and setup of everything I want to start cleaning up all my wiring, better cooling, proper cut lengths, etc

    The universal joint needs replacement as there is a few degrees of play in the yaw axis, hopefully the driveshaft joint fixes this.

    Would it be safe for me to move to 45mm CTC levers with the new PSU? Simcalc gives:
    231Nm of pitch torque and 200Nm of roll torque and a linear speed of 706.86mm/s.
    Is that enough torque for someone who weighs 85KG with this design or would I have to move to shoulder mounts?

    I plan to build a cooling array of fans for the motors and JRK's instead of the single fan I am currently using.

    A huge thankyou to everyone on the forum that's provided advice and help with building these things!

    Attached Files:

  2. Ads Master

    Ads Master

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  3. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator

    Joined:
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    Innovative tech specialist for NGOs
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    My Motion Simulator:
    3DOF, DC motor, JRK
    Disregarding mechanical loss, to know what Newtons it will take to move something it will be Mass (kg) x Acceleration (m/s) = F (N). So to move 100kg at 0.7 m/s needs 70 N. It takes 9.8N per kg to counteract gravity. Keep in mind there is significant mechanical loss in things like the gearbox, depending on the ratio you may want to allow between 10% to 50% loss for worm gears and the greater the gear ratio the higher the % loss is: http://www.meadinfo.org/2008/11/gear-efficiency-spur-helical-bevel-worm.html
  4. PMK

    PMK New Member Gold Contributor

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    Don't I also have to take into account the lever from the rod end to the universal joint as that gives a huge mechanical advantage?
    How do I effectively estimate the mass directly over the end of the CTC arm?
  5. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator

    Joined:
    Jul 13, 2014
    Messages:
    14,192
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    105,910Coins
    Ratings:
    +8,745 / 42 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    SimCalc is already giving you the numbers, including taking into account the rig dimensions and intended mass, what I was trying to add was some understanding of how to interpret those.
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