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Compact Racing Sim - 6 DOF

Discussion in 'DIY Motion Simulator Projects' started by early_m, Aug 13, 2020.

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  1. Gadget999

    Gadget999 Well-Known Member

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    My Motion Simulator:
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    Check out my 6dof build, the 100A motor drivers have been excellent
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  2. cfischer

    cfischer Active Member Gold Contributor

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    The sabertooth drives will have a max current draw. Use that to size your wire. Add a little buffer for safety.
    https://www.powerstream.com/Wire_Size.htm
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  3. early_m

    early_m Active Member

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    Sorry, could you tell me, in that table am I looking at the 'Maximum amps for
    power transmission' column?
  4. cfischer

    cfischer Active Member Gold Contributor

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    No for chassis wiring. These numbers are for steady state. Short bursts of current above these numbers should be ok. If you over load the wire the result is heat. Too much heat and you get fire.
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  5. SeatTime

    SeatTime Well-Known Member

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    My Motion Simulator:
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    I was using 2 x 60 Sabertooths and it worked OK with my light carbon frame and body weight, but needed gas shocks once I added a DD wheel/fiberglass shell or a bigger driver. It would often trip out two 200 amp DC circuit breakers when I was running it hard in Rally games (used big batteries for filtering - moved to slow blow fuses to fix the tripping) - and I had to change out two motors due to heat failure. Note that Silent Chill went from MMs to 2 x 32 to 2 x 60 Sabertooths and then Brushless. Many others have moved onto AC or brushless from standard DC motors and it was not to save money. Anyway I think I have said enough and don't want to look like I am brow beating you to change tack especially if you may be on a budget. Just wanted to give you my take on it from my own experience and what I have seen of others - although some seem to be fine ... so maybe just ignore me :). Again all the best in your project :thumbs.
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  6. early_m

    early_m Active Member

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    Great, thanks for clarifying.

    I've just checked the sabertooth spec sheet and handily they've included this info

    Screenshot_20200826-064031_Drive.jpg
  7. early_m

    early_m Active Member

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    Thanks for taking the time to provide your past experiences with DC motors. Can I asked which motors you used? I agree that they perhaps arent the best solution. But with budget and space being key it will be the route that I take. Maybe I'll live to regret it, but I have faith that there have been many successful builds with DC motors and I take encouragement from their build treads.
  8. adgun

    adgun Active Member

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    Hi
    I admire youre work
    About the motors, did you look at bldc motors nema 23 and 34, i have for €150 a nema 23 motor with driver and planetary gearbox at my door, and for €200 the same with nema 34.
    With the nema 23 you stay in H6 specs and with nema 34 you go further.
    The avantage from this is a far longer lifetime and less backlash, you must by glad to get a 5000 hour lifetime with a brusshed dc motor (brush life) and with bldc motors its bearing life 30000hour for EU brands.
    And 20000 hour for a planetary gearbox is nothing special.
    Becauce a pl. gearbox is rolling not sliding there is no chance of jitthering what often happens with big ratio wormgearboxes, and gives better motion, and will be more precice also.
    Sorry for the bad english
    regards Ad
  9. SeatTime

    SeatTime Well-Known Member

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    My Motion Simulator:
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    They were 38 amp 12V motors from Motion Dynamics - no gearbox. They are obsolete now.
  10. early_m

    early_m Active Member

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    Thanks for your kind offer, but I don't think those motors would suit my compact design. Plus I need 6 motors which, if you could provide, would be out of my budget. Appreciate the thought.
  11. early_m

    early_m Active Member

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    OK thanks. I plan to use 400W 24V DC motors with 1:50 gearbox giving 60RPM and 48Nm of torque. Rated load current is 22 amp.
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  12. Gadget999

    Gadget999 Well-Known Member

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  13. early_m

    early_m Active Member

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  14. Gadget999

    Gadget999 Well-Known Member

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    My Motion Simulator:
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    I run 3 of them and they have been faultless

    They have way more power then I need

    I run them at 20 khz
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  15. early_m

    early_m Active Member

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    OK thanks, I will look into them :thumbs
  16. early_m

    early_m Active Member

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    My Motion Simulator:
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    Made a 1:6 scale model just for fun and to experiment with setting up the DOFs.

    IMG_1734.JPG
    20200526_154037.jpg


    I'm thinking of setting it up so that pitch/roll is used for acceleration/cornering in order to have the feeling of gforce. The sim will be used with VR. Anyone got any experience of this?
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  17. Gadget999

    Gadget999 Well-Known Member

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    My Motion Simulator:
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    Looks great !

    What board did you use to control 6 motors ?

    I find tilting the sim to simulate feels a bit fake

    Surge and sway feels more relaistic imo

    With sim tools you can edit the dofs so you can add it bit of pitch and roll to any axis you want
  18. early_m

    early_m Active Member

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    My Motion Simulator:
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    used a single ard uno.

    Thanks for the info on pitch/roll.

    Ideally I'd like the initial surge to happen and then the sim starts to pitch to continue the feel of acceleration - not how you'd do that or of kts even possible?

    When you say edit the dofs, do you mean simply change the values so, for example, surge is slightly pitched instead of horizontal?
  19. Gadget999

    Gadget999 Well-Known Member

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    My Motion Simulator:
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    my susggestions

    firstly get each dof working as it should

    for surge get the rear 2 actuators to drop a bit and the front 2 to raise a bit

    i am not sure you can get the motion to move first and then apply a different motion - however in my experience the sim is always moving when you run a powerful car
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  20. Erik Middeldorp

    Erik Middeldorp Member

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    Have you seen @Dirty 's rig? He's doing what you want to do but for a flight sim. Looks really good though. https://www.xsimulator.net/community/threads/dirtys-6dof-aasd-servos.14621/page-3#post-202008
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