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3DOF with Pitch, Roll and 360º Yaw - Pulley Actuator System

Discussion in 'DIY Motion Simulator Projects' started by danalog, Oct 29, 2013.

  1. danalog

    danalog Motion Sim Wannabee

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    Hi all,

    As mentioned in the new member introduction thread, my brother and I are prototyping a few "out of the box" ideas:

    1. a 3DOF motion sim (with pitch, roll and 360º yaw), inspired by the sliding 2DOF by tahustvedt
    2. a linear actuator design I've never seen before
    The goal of the 3DOF is to create a low cost motion sim specifically for seated Virtual Reality experiences. To name a few: flight/space sims, racing and for whatever else we can think of. At this point we are just prototyping and validating our ideas.

    The linear actuator design is based on the idea of two opposing pulleys that uses one rope. For the rope we are using 4mm Dyneema DM20 which is a new kind of ultra strong fiber that does not stretch, will not creep (get longer over time) and will take 1700kg of load before breaking. Perfect for a high precision pulley system. We'll be using this actuator design for pitch and roll. For the yaw we're still brainstorming but the general idea is to use the DM20 fiber as well.

    Anyway, we're prototyping a proof of concept to find out if the idea actually works. We hope to share our findings soon and wish to share the idea by "open-sourcing" it here so everyone can use (or improve?) it.

    Here's a work in progress teaser:

    IMG_3023.JPG

    We have purchased or scavanged most of the required components:
    - bearings
    - lots of stainless steel and aluminum
    - DM20 rope
    - wiper motors (may change to higher quality but these will do for the prototype)
    - a fully loaded wood/metal workshop :)

    Wiper motors from Suzuki Samurai type SJ413
    wiper-motors.jpg

    We are still figuring out what electronics we should use.
    - Arduino with motor shield?
    - Custom electronics?
    The key here is to make it repeatable for others. Using off the shelve products are preferred.

    The Arduino combined with the Monster Moto Shield looks like it could work but I'm not sure about the voltages as it is rated for 16~41V. They also drive 2 motors and we need to drive 3 so we need two of them. It is however a cheap solution. Open for discussion...

    We're eager to try the SimTools software, I guess we don't need to wait very long as it will be released in the next few days anyway :)

    Hope you like it and I'll try to update soonish with some more pictures of our progress.
    • Like Like x 2
  2. Historiker

    Historiker Dramamine Adict Gold Contributor

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    My Motion Simulator:
    3DOF, DC motor, Arduino, Motion platform, 6DOF
    I am looking forward to seeing what you come up with!
  3. bsft

    bsft

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    looks good
  4. danalog

    danalog Motion Sim Wannabee

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    Here's a sideview sketch I made for a variable virtual pivot point.

    kruistafel-motion.jpg
    • Like Like x 2
  5. RacingMat

    RacingMat Well-Known Member Gold Contributor

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    My Motion Simulator:
    2DOF, DC motor, Arduino
    Hi Danalog!
    I'm using Motomonster: beware there is wrong voltage spec on sparkfun website. The max voltage is 16V! nothing more sadly...

    I'm eager to see more!
    Mat
    • Agree Agree x 1
  6. danalog

    danalog Motion Sim Wannabee

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    Thanks for the tip Mat. Are the amps also wrongly spec'd?
    Also, maybe you know.. is it possible to drive two Monster Moto Shields from one Arduino?
  7. RacingMat

    RacingMat Well-Known Member Gold Contributor

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    My Motion Simulator:
    2DOF, DC motor, Arduino
    The amps should be correct. I'm using 8Amp per motor in 12VDC

    You can drive 2 motomonster with one Arduino UNO ... but you cannot stack them ;)

    With an Arduino UNO,
    you need to connect ground and 5V to the 2 motomonsters
    and you need 6 + 6 pins for pwm and directions (from D2 to D13) OK
    plus 3 Analog pins for pots ! (from A0 to A5) OK

    your Arduino will be full! but it's Okay :cool:

    Arduino /..Motomonster1
    ......GND <-> GND pin
    ........5V <-> 5V
    .....pin 4 <-> pin 4 inA motor1
    .....pin 5 <-> pin 5 pwm
    .....pin 6 <-> pin 6 pwm
    .....pin 7 <-> pin 7 inA motor2
    .....pin 8 <-> pin 8 inB motor1
    .....pin 9 <-> pin 9 inB motor2
    • Like Like x 1
  8. danalog

    danalog Motion Sim Wannabee

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    That's great Mat, I'm very happy with that. Just ordered an Arduino Uno R3 and two Monster Moto Shields at dx.com (with a discount and free shipping, great deal!).

    I just remembered I still have a few old server power supplies rated at 12V 96A, probably enough power.
  9. eaorobbie

    eaorobbie Well-Known Member SimTools Developer Gold Contributor

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    My Motion Simulator:
    2DOF, DC motor, JRK, SimforceGT, 6DOF
    Be nice to see it moving , a design we have not seen, mmm Interesting.
  10. danalog

    danalog Motion Sim Wannabee

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    We moved it with a powertool, it worked... but not very well. The rope got stuck because it was too thin. That was a standard 2mm Dyneema rope, obviously not good enough. This is the reason we upgraded to 4mm DM20 rope, it doesn't get stuck and is much stronger. It is in fact a way too strong: 6 * 1700kg = 10200kg. We will never get a load on one actuator that high but we need the 4mm diameter to prevent the rope from getting stuck and to loop it over the driving wheel without slipping.

    It does however open possibilities of creating simulators that can handle high loads if you would use strong motors. I have two old school 36V tape drive motors, would be fun to see what kind of loads we can handle with those. These motors have electromechanical breaks that needs to be powered before they can turn so we probably don't need any (worm) gearing if we can match the pulley loops to the right reduction (added benefit of pulleys).
    • Like Like x 2
  11. RacingMat

    RacingMat Well-Known Member Gold Contributor

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    My Motion Simulator:
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    Last edited: Oct 31, 2013
  12. eaorobbie

    eaorobbie Well-Known Member SimTools Developer Gold Contributor

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    My Motion Simulator:
    2DOF, DC motor, JRK, SimforceGT, 6DOF
    Need a decent h bridge or motor controller and for sure we should be able to make these drives spin, and yes pulleys can be a lot more friendly in finding the torque(ratio) for the best movements.
    There is a couple of options to drive these with a couple of different micro controllers.
    There is a another member Omniatlas,is looking at driving a 2 man flight deck , around 350kg, your idea sounds what he is looking for, but a decent 12v worm gear would work, 150 rpm too quick.
    Would love to see your idea moving.
  13. danalog

    danalog Motion Sim Wannabee

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    Received the Monster Moto Shields today :)
    Arduino Uno is on back-order. Ordering one form a local vendor today as I don't want to wait for dx.com.

    IMG_3058.jpg
  14. Historiker

    Historiker Dramamine Adict Gold Contributor

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    My Motion Simulator:
    3DOF, DC motor, Arduino, Motion platform, 6DOF
    Let me know how it turns out. I also ordered a couple of those.
  15. danalog

    danalog Motion Sim Wannabee

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    The power supplies:
    IMG_3046.jpg

    The DM20 rope:
    IMG_3045.jpg

    22mm ball wheel (pot), we' be using three of these as bearings for the 360º yaw movement:
    kogelpot-22mm.jpg

    @Historiker, I'll post my progress here.
    • Like Like x 1
  16. danalog

    danalog Motion Sim Wannabee

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    And today came the Arduino Mega (Uno was out of stock at local supplier) and 6 neodymium magnets for the hall effect sensors.
    We have all components. Lets start the build!

    My brother is doing the hardware while I'm focussing on the software.

    Now, the software. I need to program the Arduino Mega. I found "X-PID-Arduino-PID-motor-control" on Github but it is from "the other" x-sim site. It looks like a good starting point though as it has the capability for a 360º axis.

    @RaceRay, do you have any advice how to progress?
  17. eaorobbie

    eaorobbie Well-Known Member SimTools Developer Gold Contributor

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    My Motion Simulator:
    2DOF, DC motor, JRK, SimforceGT, 6DOF
    Not 100% sure code will run here. Maybe little modification and we could get to run here, Prilads is more stable for 2dof plus he provides a nice little app to go with it.
  18. Historiker

    Historiker Dramamine Adict Gold Contributor

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    My Motion Simulator:
    3DOF, DC motor, Arduino, Motion platform, 6DOF
    I can attest that RacingMat's code works great as well. We have lots of options here! :thumbs
  19. danalog

    danalog Motion Sim Wannabee

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  20. danalog

    danalog Motion Sim Wannabee

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    I've searched the interwebs for Prilads code but I can't find it. Do you where it is?