1. For downloading SimTools plugins you need a Download Package. Get it with virtual coins that you receive for forum activity or Buy Download Package - We have a zero Spam tolerance so read our forum rules first.

    Buy Now a Download Plan!
  2. Do not try to cheat our system and do not post an unnecessary amount of useless posts only to earn credits here. We have a zero spam tolerance policy and this will cause a ban of your user account. Otherwise we wish you a pleasant stay here! Read the forum rules
  3. We have a few rules which you need to read and accept before posting anything here! Following these rules will keep the forum clean and your stay pleasant. Do not follow these rules can lead to permanent exclusion from this website: Read the forum rules.
    Are you a company? Read our company rules

my 2DOF +/-30 degrees tilting chair mosim

Discussion in 'DIY Motion Simulator Projects' started by steveh2112, Oct 14, 2016.

  1. steveh2112

    steveh2112 Member

    Joined:
    May 12, 2014
    Messages:
    104
    Occupation:
    semi retired
    Location:
    Phuket, Thailand
    Balance:
    1,024Coins
    Ratings:
    +22 / 0 / -0
    My Motion Simulator:
    2DOF
    so i have the mechanical part of my project working now so i thought i would start a new thread. i'm waiting for the arduino board and some other stuff and giving recent news in Thailand, i think the post office is going to running a bit slower than usual so that may take a while.

    anyhow, here is my design. it uses 2x 200w 24V worm drive motors and a 6:1 gearing system using motorbike parts. the gears get me down to about 400mm/sec at 140mm radius and 666N force to drive the chair, with a range of about 250mm. this gives me about +/- 30 degrees of lean which i hope will improve the sensation on flight sims.

    i can't drive it from the computer yet, but i hooked up the motors directly to a couple of car batteries while i wait for my PSU to arrive. it really moves me around with a lot pf power!

    the springs are designed to equalize the forces so it should be symmetrical in speed when going from level to full tilt and then back. the chair pivot is 700mm high to accommodate the +/- 30 degree tilt.

    the final cost, not including racing seat, is about $500.

    UPDATE, want to skip the BS as see it working?
    https://www.xsimulator.net/communit...s-tilting-chair-mosim.9181/page-3#post-118414
    and how i built it
    https://www.xsimulator.net/communit...s-tilting-chair-mosim.9181/page-3#post-118604

    Attached Files:

    • Agree Agree x 1
    Last edited: Nov 24, 2016
  2. Ads Master

    Ads Master

    Balance:
    Coins
    Ratings:
    +0 / 0 / -0
  3. outrunner

    outrunner Run to get the race leader flag!

    Joined:
    Oct 7, 2016
    Messages:
    53
    Occupation:
    father mother
    Location:
    Italy
    Balance:
    578Coins
    Ratings:
    +8 / 0 / -0
    My Motion Simulator:
    Arduino
    Looks like you have room for a 60° tilt, which (if my fly lessons from '95 are still imprinted in my mind :nerd) is the "other" standard tilt in aeronautics
  4. MarkusB

    MarkusB Active Member Gold Contributor

    Joined:
    Jun 30, 2015
    Messages:
    451
    Location:
    Germany
    Balance:
    3,357Coins
    Ratings:
    +432 / 1 / -0
    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, Motion platform
    That's really an interesting construction! I'm looking forward to seeing it in action when it's hooked up to DCS. Hope you get your parts soon.
    Where do you plan to mount the pots? At the motor axis (which would probably need a multi-turn pot) or at the large wheels?
  5. choclo

    choclo Member

    Joined:
    Sep 27, 2016
    Messages:
    34
    Location:
    Vienna
    Balance:
    344Coins
    Ratings:
    +28 / 1 / -0
    Wow... Things are getting double-decker hier :) Looking forwards for the results...
    :popcorn
  6. steveh2112

    steveh2112 Member

    Joined:
    May 12, 2014
    Messages:
    104
    Occupation:
    semi retired
    Location:
    Phuket, Thailand
    Balance:
    1,024Coins
    Ratings:
    +22 / 0 / -0
    My Motion Simulator:
    2DOF
    the pots will go on the big wheels, they will turn about 140-160 degrees in normal use, so should be good range for my pots.

    i saw this video
    that thing looks amazing, i especially like that it goes up and down so much.
    i know i can't help myself, as soon as i get this current design working, i'll start on the next one

    i was thinking the push system on there is quite complex and needs to be very strong, but i have an idea that i've never seen before, maybe someone could point me to an example.

    my idea is i build a big frame with a plywood base and 2"x4" corner posts and top beams, about 4' wide, 6' long and as tall as i can fit in my game room, so about 9' high. at 3 points on the top of the frame are 3 of the same motors i'm using now with the motobike front sprocket.

    there is a 2m long chain hanging over each sprocket, connected to steel wire that connects to 3 suspension points on the chair which is dangling in the middle of the tall frame. on the other side of the sprockets, the chain is connected to counterweights, that make the chair and ridder statically neutral

    so the motors can lift or lower the 3 chair pivot points to give pitch, roll, and vertical movement, at about 500mm/sec. i think i should be able to get at least +/-45 degrees of pitch and roll and maybe more than 1m of vertical lift/drop.

    for position feedback i'd use a multi turn pot on the motor shaft.

    anyhow, it would be an awesome project and i think quite original, and i can reuse all the expensive parts of what i have now.

    P.S. just thinking about the math again, the 200w motors i have give 20Nm Torque, and the radius of the drive sprocket is 30mm, so that's 666N at 30mm. so there are 3 motors potentially lifting me and the chair, so that's 2000N lifting (or lowering) about 90kg for me, chair, joysticks, headset, etc. so that's 22N per kg. BUT, because of the counterweights needed to equalize the downward gravity force on the chair, the weight is actually 2x90 so 180kg which gives 11N/kg.

    One newton is the force needed to accelerate one kilogram of mass at the rate of one metre per second squared in direction of the applied force.

    so that means i'd get about 11m/ss of acceleration, which is slight over 1G. is this math right?

    Attached Files:

    • p1.jpg
      p1.jpg
      File size:
      163.4 KB
      Views:
      493
    • p2.jpg
      p2.jpg
      File size:
      245.6 KB
      Views:
      492
    • p3.jpg
      p3.jpg
      File size:
      199 KB
      Views:
      502
    • p4.jpg
      p4.jpg
      File size:
      184.3 KB
      Views:
      457
    Last edited: Oct 16, 2016
  7. Nick Moxley

    Nick Moxley Well-Known Member

    Joined:
    Dec 13, 2013
    Messages:
    2,785
    Occupation:
    Owner/Operator- Moxleys Rantals
    Location:
    Winnipeg Manitoba Canada
    Balance:
    17,363Coins
    Ratings:
    +2,496 / 30 / -2
    My Motion Simulator:
    2DOF, 3DOF, DC motor, JRK
    Napkin calculations, Oh how some like to learn the hard way.

    3 motor's.....500mm/s......45 deg.......urr ya good luck with that.
  8. mprofitt

    mprofitt New Member

    Joined:
    May 27, 2014
    Messages:
    23
    Balance:
    131Coins
    Ratings:
    +8 / 0 / -0
    I would like to see the napkin calculations. Can you scan the napkin?
  9. steveh2112

    steveh2112 Member

    Joined:
    May 12, 2014
    Messages:
    104
    Occupation:
    semi retired
    Location:
    Phuket, Thailand
    Balance:
    1,024Coins
    Ratings:
    +22 / 0 / -0
    My Motion Simulator:
    2DOF
    i was under the impression i'd spelled out all my calculations in my last post, the one where i came to the conclusion i should get 1G up or down (effectively, weightless down). did i miss something?

    on the CAD drawing i attached above, i verified that at least mechanically, +/- 45 degree pitch and roll is possible, but unless i can get a lot of height for the rig, it would be hard to get much vertical range while leaning.

    i think my next step is to build a scale model just to see what's possible.
  10. OZHEAT

    OZHEAT Member

    Joined:
    Oct 26, 2015
    Messages:
    175
    Location:
    Australia
    Balance:
    2,027Coins
    Ratings:
    +86 / 6 / -0
    My Motion Simulator:
    3DOF, DC motor
    Looks like your cad drawings are depicting a mechanical swing.
    I also agree that your calcs are way off.
    • Agree Agree x 1
  11. steveh2112

    steveh2112 Member

    Joined:
    May 12, 2014
    Messages:
    104
    Occupation:
    semi retired
    Location:
    Phuket, Thailand
    Balance:
    1,024Coins
    Ratings:
    +22 / 0 / -0
    My Motion Simulator:
    2DOF
    i can't wait to see the corrected math
  12. OZHEAT

    OZHEAT Member

    Joined:
    Oct 26, 2015
    Messages:
    175
    Location:
    Australia
    Balance:
    2,027Coins
    Ratings:
    +86 / 6 / -0
    My Motion Simulator:
    3DOF, DC motor
    Well for correct math you would need to provide specs on the motor and gearbox.
  13. steveh2112

    steveh2112 Member

    Joined:
    May 12, 2014
    Messages:
    104
    Occupation:
    semi retired
    Location:
    Phuket, Thailand
    Balance:
    1,024Coins
    Ratings:
    +22 / 0 / -0
    My Motion Simulator:
    2DOF
    https://www.motiondynamics.com.au/worm-drive-motor-12v-24v-200w-180-rpm-20nm-torque.html

    • 24v No Load Current: 0.9A

    • Rated Torque:20 Nm (Locked Rotor Torque)

    • Optimal torque: is 12.5Nm
    • Motor Speed:3600 RPM/160-180 RPM at Gearbox dependant on load.

    • Rated Current 12/24 Volts:16amps at 12v OR 8 Amps FOR 24v, No load rating of 1A

    • 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.
    • Informative Informative x 1
  14. OZHEAT

    OZHEAT Member

    Joined:
    Oct 26, 2015
    Messages:
    175
    Location:
    Australia
    Balance:
    2,027Coins
    Ratings:
    +86 / 6 / -0
    My Motion Simulator:
    3DOF, DC motor
    Typical sales bullshit!!!
    Rated Torque:20 Nm (Locked Rotor Torque) so they call stall torque, rated torque....Wrong(maybe thats what they base their BS specs on)

    Ok looking at the PDF specs on G180-12 (12v version), I know yours is the 24v version so approx half the 12v motor current.
    www.motiondynamics.com.au
    G180-12

    Voltage 12V-16VDC
    Motor Power 180W
    No Load Current 1.8A
    Rated Current 16A
    Stall Current 32A
    Torque 20N.m
    No Load Speed(RPM) 180RPM
    Rated Speed(RPM) 150RPM
    Gearbox Ratio 25:1

    No speed/torque/current curve graph so what they actually base their ratings on is a bit of a mystery.

    OK then.
    You cannot use Locked rotor torque for your calculation, it only applies when the motor is starting or stalled(locked).
    Once the motor is moving the torque drops off significantly at rated.

    If you take their Optimal torque: is 12.5Nm (which looks suspiciously like a calc that I will describe later) to maybe mean their Rated Torque

    Stall current maybe plausible 32A@12V or 16A@24, Hmmmm going by this spec a single MM isn't suitable and NO bridging 2 chips on the MM WILL NOT double the amp capacity. It will Halve the RdsOn value but that is another subject.

    Rated current 16A@12v or 8A@24v If we look at the stall current @32A, the rated current is half of stall current. Hmmm at that level I would say the duty cycle would be ~10 - 20% or 1 min ON, 9 min OFF to 2 min On - 8min OFF.
    A motor with 100% duty cycle will typically have a rated current of a third of stall current.

    When we look at their "rated torque" compared to their "optimal Torque" it looks like they worked that out by multiplying the gearbox efficiency of 60-65%.

    So there you are, your using BS sales blurb which doesn't make sense for your calculations.
    If you want to truly know what the output of the motor & gearbox you are going to have to do a speed/torque/current graph of your own.

    Cheers Andy

    PS, no comment on your swing design?
    • Informative Informative x 1
  15. steveh2112

    steveh2112 Member

    Joined:
    May 12, 2014
    Messages:
    104
    Occupation:
    semi retired
    Location:
    Phuket, Thailand
    Balance:
    1,024Coins
    Ratings:
    +22 / 0 / -0
    My Motion Simulator:
    2DOF
    ok, so if it is more like 12.5Nm, not 20Nm i used above, that means i would only get just over 1/2 a G with my design. not sure if that's enough to make it interesting really.

    anyhow, this 2nd idea is just something of a brain fart at the moment, the rig i have running now in the 1st post (the mechanical part at least) has easily enough power to move me around at about 120 degrees/sec which is about 1/2 what an f16 can do, so that's good enough for me.
  16. steveh2112

    steveh2112 Member

    Joined:
    May 12, 2014
    Messages:
    104
    Occupation:
    semi retired
    Location:
    Phuket, Thailand
    Balance:
    1,024Coins
    Ratings:
    +22 / 0 / -0
    My Motion Simulator:
    2DOF
    i have a question about the oculus sensor, should it be stationary or mounted on the moving part of the rig? and what's the ideal place for it? thanks'
  17. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

    Joined:
    Jul 13, 2014
    Messages:
    14,952
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    110,426Coins
    Ratings:
    +8,946 / 43 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    The ideal would be motion cancellation, where the rig movement is subtracted from the Rift view.

    Unfortunately Palmer emphatically stated that Oculus will not make it possible for a generic form of motion cancellation. VectionVR did make a modified LibOVR file for developers to compile with games to provide motion cancellation, but that never took off.

    On fast small axis movement sims you can get away with having the Rift camera off the rig. But for large axis movement sims you need to mount the camera on the rig and the likes of @SeatTime have had good success using a gyro gimbal mount.
  18. steveh2112

    steveh2112 Member

    Joined:
    May 12, 2014
    Messages:
    104
    Occupation:
    semi retired
    Location:
    Phuket, Thailand
    Balance:
    1,024Coins
    Ratings:
    +22 / 0 / -0
    My Motion Simulator:
    2DOF
    'a gyro gimbal mount.' i wasn't expecting that. i just looked at seattime's thread here
    https://www.xsimulator.net/community/threads/seattimes-6dof-dc-build.6106/
    didn't see anything about the oculus sensor yet. anyhow, i'll check into it

    i just tried moving my head in a pitch and roll kind of movement the same way it would work in the mosim. i think pitch isn't a problem if i mount it to the moving part of the rig in front of me.

    but roll is a problem. the view in my headset is wrong, when i lean to the side, i'm leaning in the cockpit which is not what i want. and regardless if i lean the sensor or not, its the same problem.

    need to think about this

    thanks
    Last edited: Oct 17, 2016
  19. steveh2112

    steveh2112 Member

    Joined:
    May 12, 2014
    Messages:
    104
    Occupation:
    semi retired
    Location:
    Phuket, Thailand
    Balance:
    1,024Coins
    Ratings:
    +22 / 0 / -0
    My Motion Simulator:
    2DOF
    i just asked on the oculus forum too
    https://forums.oculus.com/community...simulator-what-about-position-sensor/p1?new=1

    i see the problem. when my whole body is leaned on my side, oculus has no way of knowing its my whole body (including head) leaning, it will assume its just my head. i need a way to unlean the view in the game, otherwise when i'm on a big roll, my head is fixed with reference to my body, and the cockpit, but oculus thinks i'm leaning, so the view in DCS is leaning. problem is, i'm not sure DCS even has a view lean command.
    Last edited: Oct 17, 2016
  20. MarkusB

    MarkusB Active Member Gold Contributor

    Joined:
    Jun 30, 2015
    Messages:
    451
    Location:
    Germany
    Balance:
    3,357Coins
    Ratings:
    +432 / 1 / -0
    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, Motion platform
    My first approach would be - and in fact it was and still is - to try small & fast movements and check if this feels right for you. For me it does, and I will keep my 2DOF rig with a tilt of about 10 degrees in each roll and pitch direction. And I am also mainly interested in flight simulations.

    One advantage is that motion cancellation is no issue at all. I never recognized any disturbance caused by the seat movements.

    The reason for this recommendation is that with your current state of development it would be quite easy to just try it out: Mount the lever directly to the motor axis, which will reduce the angle but increase the speed. Then spend some time in configuring your profile (which is one of the most essential steps), put on the VR headset and check the feeling.
    You won't lose much time with this little experiment. And maybe you will find out that it works well for you.
    And if not, you can still go on with the gyro mount or fixing the games. :)

    One additional note: The actual idea behind most motion platforms is not (at least in my understanding) to get as close as possible to the real movements of the simulated vehicle. Instead the idea is to fool your brain. And at least my brain is really gullible in this respect.
  21. steveh2112

    steveh2112 Member

    Joined:
    May 12, 2014
    Messages:
    104
    Occupation:
    semi retired
    Location:
    Phuket, Thailand
    Balance:
    1,024Coins
    Ratings:
    +22 / 0 / -0
    My Motion Simulator:
    2DOF
    thanks markus, but i'm more interested in experimenting with what's possible with VR and motion simulators than simply building something that is known to work. i can always limit the range in software if i really can't make +/- 30 degrees work properly with the headset.

    i found this thread
    https://www.xsimulator.net/communit...ft-will-support-motion-simulators.6352/page-2
    noorbeast, i see seattime's comments about stabilizing the sensor on page 3

    interesting stuff. i'm going to look into this problem a bit more this week.
    Last edited: Oct 18, 2016