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Wormmotor any good?

Discussion in 'SimTools compatible interfaces' started by bever24, Apr 5, 2012.

  1. bever24

    bever24 New Member

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    Hi,
    I am hoping to be able to make a motion platform ((almost) without any technological or electronical knowhow;) )
    I managed to get a few identical dc motors almost for free, but I have no idea if they are suitable for the job and I was hoping that perhaps people here could advice me on that.
    They are 150 Watt Permanent magnet DC electric worm gearmotor wheelchairmotors. ( Micro-Motor AG PMGSt 80/45L 150 watt 24VDC ). ( They look a bit like these, although not quite the same: http://www.directindustry.com/prod/micr ... 63775.html )
    They are fitted with 7 cm beltdrive 'disks/cogs?' that rotate about 1.7 times per second.

    What I'm hoping for in a motionplatform is something with fast and strong movement. Something suitable to make a rollercoastersimulator with.

    Also, as these are wormmotors, i am afraid that these will result in jerkey movement.
    If the motor isn't powered, then the platform abruptly stops.. right?
  2. bever24

    bever24 New Member

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    I just read a bit further in the forum that 50-65 RPM would be desired. Would it make sense to find a solution to gear them up, or will this be such an undertaking that it's best to just leave these motors and search for better ones?
  3. bsft

    bsft

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    If you want big worm gear motors with speed, try these http://www.motiondynamics.com.au/worm-d ... orque.html , I use them and they are good, more like 100-180 rpm, They need some serious power to drive them though. Heres a video of how well they go http://www.youtube.com/watch?v=ZbN8XF027lc
    For control boards , for simplicity, go to the famous Pololu JRK http://www.pololu.com/catalog/product/1393 , plenty of us use them , they are easy to set up. One board per motor, 7 wires per board, one usb cable per board, and by golly do they perform well!
    Cheers, David.
  4. bever24

    bever24 New Member

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    Thanks for the advice, but my main questions remain.
    - Are my wormmotors any good, or should i get others?
    - Are wormmotors the best type of motors for motion platforms, or do they result in less fluent motion?
    (i assume the less fluent motion because i have a small wormmotor that if i where to rotate the axis by force, I would destroy the gears, the 150 watt motors have to much resistance to try this without mounting it and adding some stick or so, so i assume when they are not powered. they will instantly stand still and stay in that position.)
    As for the power supply, atm i have a 24 Volt, 20 Ampere supply, but if a different supply is needed for different motors, then so be it.



    ---
    Although much further on in the project, as for the controllers I plan on using a bit of an alternative method, However, as I do not have the knowledge to design circuitboards myself, this might be to complex for me to make.
    What I'm planning to use is a Falcon haptic controller http://www.youtube.com/watch?v=gjAxGVH1JOM
    as usb interface, and connect motor controllerboards to that.
    This will give me
    - Access to a ready made scripting language + dlls and memory reading tools
    - The option to make very complex and unique effects
    - Absence of need for c programming, or premade sim applications.

    The Falcon controller consists of 3 x Mabuchi RS-555PH-3255 Brushed DC Motors (rated 5000 RPM, 12 V, 3 A) connected to 3 encoders (which i can resize and print on plastic for use with bigger motors) and are driven with a 1 Khz resolution. Although i haven't measured the voltagerange yet, i assume these motors get driven with a range of -12 to +12 volts.
    I was hoping to be able to connect 3 Ocean Controls kit No KT 5198 http://store.qkits.com/moreinfo.cfm/KT-5198A.pdf (or other 1ms 2 directional motor controllers) to that.
    The problem with this is that they accept a 0-5v range of input, and not -12 to +12. Wether or not i will be successful will depend on if this -12 +12 range can be converted to a 0-5v range.(where 2.5v = 0rpm).
    If this wont work, then i will interface it the default way, but for now I'm still hoping for this solution.

    However, the project starts with good motors, so that's step one :D

    (*The platform i'm hoping to build is a 3 dof platform that i can place under my 3 seater couch, if this appears to be to hard due to the force and precision required for the y-axis, then i will settle for now with a 2dof platform for under the couch :D)
  5. bsft

    bsft

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    Wormgear motors are fine, its the strength of the gearing and how the sim is setup is the issue. The big motors are very strong, I have abused mine very hard.
    Wipers are more sensitive , but still do well.
    SCN5 and 6 actuators are better, but they do not move much weight and are EXPENSIVE.
    Design a frame and post it so we can advise and help.
    Cheers, David.
  6. bever24

    bever24 New Member

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    Did you refer to mine being strong enough, in essence saying that the once i have can indeed be used for a motion platform?

    (These are screenshots of the motors i have and the gears (i have 8 working, and 9 broke .. the gear in the photo is broken;P)

    [​IMG]



    [​IMG]




    The reason i don't have a design yet, is because some of this stuff is really expensive or rare. Its better to see what i can get, and try to build around that.

    Perhaps the slow speeds of my motors would allow me to build a 2, or 3 dof platform of this type:

    [​IMG]

    I like the design very much, but 3 dof might be to much for me to start with, and 3 x 150watt probably wont be able to push +- 200 - 300 kg (couch + 1 or 2 fat persons;) up.
  7. bsft

    bsft

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    That is a nice 3 DOF but shows 240 3 phase motors for movement. They would move probably over 400 kg each motor.
    I'd say the way you may have to go for a 3 DOF , is a centre spring to alleviate the weight against the motors.
    This guy, Aldoz has done well using 12v winch motors and a centre spring my-3dof-project-is-born-t3096.html , go through the whole thread. The videos are awesome to watch the movement.
    Also, here is someone else having a go at a 3 DOF 3dof-ac-motor-t2556.html
    Cheers, David.
  8. bever24

    bever24 New Member

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    with spring would then be something like this:
    [​IMG]

    thanks a lot for your help so far, i still have a few questions i hope you can help me with.
    -Is it harder to control a motor configured like in the motion platforms i pasted in this thread, that has all movement within 180 degree of one rotation, or is it harder to control a motor configured in a way that it must do multiple rotations before reaching the maximum or minimum point of that axis from the motionplatform?

    -How do i find out if my motors are strong enough to push a platform within 180 degree of rotation instead of with multiple rotations?
    I cant find any more information on the internet then is written on the motors themselves which is:
    Also, based on this:
    http://wiki.answers.com/Q/Convert_10000_min.-1_to_rpm
    I thought 3500min-1would be 3500 RPM, but considering the fact that while testing this was about 1.7 rotations per second and not 58, i must have been very wrong in this assumption (or am i a fool in expecting the motor to perform at 100% speed when connected directly and without controller to a dc power supply?.. or was it not powerful enough?.. or.. or might i have been testing them with the brakes on and do they need to be powered to be off..lol, that would be stupid, ill try that right away :p)
  9. bever24

    bever24 New Member

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    lol.. it appears that the brakes are on per default, and that i have been testing them with their brakes on and probably have been labeling those with to good brakes as broken ;P (I wasn't kidding when i mentioned my absence of experience in all required fields:p)

    in any case, without the brakes on their rpm is about 4 rotations per second. Also i was measuring the power consumption of the power supply, and that dropped from 1000 watts to 35 watts :p (so i guess i must expect to peak at 3 Kw at maximum force? .. that probably also means my power supply wont suffice for 3 of those motors.)

    as for documentation.. these are the same type, although they look a bit different:
    http://www.micromotor.ch/go/?action=Doc ... c_id=10167
  10. bever24

    bever24 New Member

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    How much Nominal torque would be required to build a platform like the above?

    In the Micro-Motor PMG type motor pdf, i can find the following info:
    - the brake is 24VDC, 5 Nm
    - an 800 watt motor of this type has 60 Nm nominal torque, and a 100 watt motor of this type has 5Nm

    At 800 watt, Nm is 800 / 60 = 13.3 times less then nominal power.
    At 100 Watt, Nm is 100 / 5 = 20 times less then nominal power,
    So in the least favorable situation my motor is 150/20 = 7.5 Nm
    and in the best possible situation it is 150/13.3 = 11,3 Nm

    A different way to estimate nominal torque might be by using the difference in speed with and without the 5Nm brake on,
    with brake, rotations per seconds = 1.7
    without brake its (harder to eyeball) about 3.7 rotations per second.
    meaning 5Nm represents about 2 rotations per second, or about 54% of total power, meaning the motor should be about
    9,26Nm nominal torque.

    is this enough for this type of platform?
  11. bsft

    bsft

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    OK, I am out of my league here, can anyone else help?
    And did you read Aldoz thread I posted? it may have some answers.
  12. jyrki.j.koivisto

    jyrki.j.koivisto New Member

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    Motor speed would be the said 3500rpm, but a wormgear is a reduction gearing so the speed will drop but the torque will increase...
  13. bever24

    bever24 New Member

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    @bsft, I have read a couple of pages but not all. Monday i will read the rest, but for the biggest part they are all far beyond where i am, which is to determine the usability and limits of the motors, as well as trying to find the path of least knowledge required ;P
    @jyrki
    tnx, i think you are correct, actually the 15:5:1 ratio is only written on some motors, and while writing this today was the first time i see it, but that did seem to give the final clue :)
    3500min-1 / 15:5:1
    would then be
    (3500 / 3) / 5 = 233.33 rpm = 3,89 rotations per second (which means i am a good rpm eyeballer ;) )

    This Nm, i tried to find out its meaning on wiki, but how am i to translate this value. if a nominal torque rating is 10Nm, then how many kilos can it push without further gearing?
  14. jyrki.j.koivisto

    jyrki.j.koivisto New Member

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    With 10Nm you could lift aprox. 1kg on a 1 meter lever, but no one has that long levers on their sim. If the lever is 100mm then it could lift 10kg
  15. BartS

    BartS Member

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    Jyrki in my opinion is one of the best people that you can have to get advise from on this site and has pointed me in the right direction before. His advise is alway 100% reliable, a well respected member of x-sim IMHO to receive advice from.
  16. tahustvedt

    tahustvedt Member

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    Which motor are you talking about? What are its specs?
  17. bever24

    bever24 New Member

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    thanks a lot for all the help.
    So in conclusion this means my motors are way to weak for attaching levers directly to them, and what i would need for that would be in the range of 120 - 150 Nm.

    I messaged the company for further specs, but i dont expect the 10Nm to be far off.

    i guess then now is the time to research motion platforms with weaker motors to find out if what i'd like, can be achieved with this hardware.
  18. bsft

    bsft

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