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DIY 2DOF Arduino Powered Race Sim

Discussion in 'DIY Motion Simulator Projects' started by ntbutler, Aug 16, 2017.

  1. SeatTime

    SeatTime Well-Known Member

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    My Motion Simulator:
    AC motor, Motion platform
    I would also recommend you try the SMC3 controller code for the Arduino. It has a configuration app, which makes setting up very simple.
    • Agree Agree x 1
  2. ntbutler

    ntbutler New Member

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    My Motion Simulator:
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    Right, so nearly a year on, I've finally got my butt in gear again to get this project sorted.

    After biting the bullet and buying another, different motor, it turns out the setup I had was OK, but the motors I'd bought just didn't like being driven with the Monster Moto shield - at least in one of the two directions.

    I found another post from @noorbeast (you are a champ mate!) pointing me to the motors I have now - from MotionDynamics here in Australia - https://www.motiondynamics.com.au/worm-drive-motor-12v-24v-200w-180-rpm-20nm-torque.html

    After ordering a couple of those, I checked out another post HERE that shows how to run each motor with it's own Monster Moto shield. I then jumped onto easyEDA.com and made up a quick custom PCB design, then used JLCPCB.com to have the boards printed - 5 boards delivered for roughly $21USD. The plan here was to be able to easily drop in a new Arduino / monster moto shield if I every blew up a component again. Here's the design:
    pcb.png

    So the plan was that I'd solder in some female headers for the monster moto shields, and male headers for the arduino. Then then basically flip the arduino upside down and just pop it on top of my PCB, and slot in the Monster Moto shields, and away I'd go.

    Unfortunately I'd stuffed up the placement of the Arduino pins - so long story short, the arduino now sits underneath this PCB.. oops.. But for $20USD, I'll end up just tweaking the design and having some new ones sent out. This design will also be updated shortly with some sort of connector added so I don't have to solder the 12V lines to the monster moto shield. Currently I haven't got a connector rated to a high enough amperage between my PCB and the power supply / motor lines, so I'm still soldering onto the shield, but that will change soon.

    So, just waiting now on another monster moto shield, and it should be good to go! Will post back soon with how things have shaped up..


    One quick questions for those SMC3 users out there - after so many modifications to my frame recently, it's a little out of balance (rear-heavy). I'll be tweaking things a little to make it more neutral, but I have noticed in my testing, that these particular motors don't have much holding torque. So when I'm sitting in the seat, the arm drops a bit, then the driver kicks in and re-corrects. It then dis-engages, and the motor arm drops again, so my seat is going up and down all the time.

    Is there a way in SMC3 to help stop the motor dropping? As mentioned, I'll try to cure most of this by balancing the sim frame better, but because I will be running a couple more games nights for kids in the coming weeks, I don't want to have to muck around with balancing the frame when different kids get in and out..

    Cheers!
  3. Gadget999

    Gadget999 Well-Known Member

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    My Motion Simulator:
    2DOF, DC motor, Arduino, 6DOF
    do the motors have a gearbox ?
  4. ntbutler

    ntbutler New Member

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    My Motion Simulator:
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    It does come with a gearbox, but after ordering (always after....) I did see this on their website:
    Holding torque : Low Holding torque, we've found these are quite easy to back drive, so if you need a worm drive with holding power this worm drive is not suitable.

    So looks a little like I've bought the wrong motors again. I'm hoping I can cure this with some extra weight on the front, but I do recall seeing in the Arduino code I had originally used before switching to SMC3 that there was an option in that package to use a "VCC Breaked" option, so wasn't sure if there was anything in SMC3 like this.
  5. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
    3DOF, DC motor, JRK
    The 25:1s from Motion Dynamics can be back driven by hand when not powered on, but are quite powerful when powered on. As long as your rig is properly balanced and has adequate design leverage then they will be fine.

    I use the same Motion Dynamics motors with my compact sim, but with 60:1 gearboxes, as my compact design needs a bit of torque and can handle users 130+kg. The 60:1s can't be back driven by hand or user load.
  6. Gadget999

    Gadget999 Well-Known Member

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    2DOF, DC motor, Arduino, 6DOF
    i use some wheelchair motors - they work great
  7. ntbutler

    ntbutler New Member

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    Crap electronics strikes again. I've tested both motors are working with the moto monster shield that I've had here for a while. I tested it out in the custom PCB I had made, which meant I could easily move the driver shield around to drive the other motor, and it worked great.

    I then had some new driver shields delivered, and again got stuck with neither of them being able to drive either of the motors in reverse. Super irritating, as I've now just bit the bullet and spent around $160 getting the original shields from sparkfun, instead of the $10 I have been spending... Well, because of all of the issues I've had lately trying to get some new shields delivered, if the ones that are 'in the mail' all arrive, I'll be have 6 boards to test with (4 knock-off and 2 legit), so guess I'll wait and see.
  8. ntbutler

    ntbutler New Member

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    Alrighty, well about time I probably posted an update.

    The legitimate Sparkfun driver boards worked straight away, so lesson learned.. After dropping them straight onto the custom PCB I had made, all worked well. I've gone with using the coolers mentioned at https://www.xsimulator.net/community/threads/xilence-cooler-for-moto-monster-sparkfun.6277/ which are also working well. I know others have asked about how to mount these, and I'd be interested if anyone has a good way. I've gone with cable ties for now, which I'm not so keen on, but it's working for now.

    Now that I have motion working, I'm starting to find a couple of things that need a little tweaking, so a few things to possibly look out for if you're just coming into this:
    • There's a little slop between my motors and the steel rod / lever arm. At this stage it's looking like I'll re-drill the hole through the rod and the motor itself and put a tight-fitting fastener through there to try to eliminate it. The effect doesn't seem too bad, but I'm sure it will be a much better experience with the slop removed.
    • For the current design (attached), the steering wheel and pedals have now lots some support due to some modifications I made to the frame. If you modify your design much, take a sec to look at how different parts are supported. I managed to have one of my potentiometers come loose during a test/calibration run (no driver), and the whole thing went off like a bucking bull. Everything seems to still be OK, but to be honest I'm surprised nothing broke - I think I got off lucky, so just a heads up :)

    One last question for anyone with a similar setup - In a couple of instances, one of my motors will get stuck at it's limit (straight up/down). I think this is stopping at the clip input limit I set in SMC Utils. But at those times, it seems to stop completely until I manually rotate it back to the neutral position. Is this expected? I have set the absolute limit a fair way past the clip limit bounds, so I don't think it's turning to that limit, but it may be - I still have to test it further. It may have something to do with the slop that I need to take out of the system, but just wanted to know if that behaviour indicates a particular limit that's set in SMC Utils being reached, or if it sounds like something else.

    Cheers,
    Nathan

    Attached Files:

  9. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
    3DOF, DC motor, JRK
    When it comes to levers they are very ineffective with respect to torque if they are using more than 40 degrees up and 40 degrees down.