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

3 dof inspired by h3

Discussion in 'DIY Motion Simulator Projects' started by Jordan Casalini, Apr 26, 2022.

  1. Jordan Casalini

    Jordan Casalini Member

    Joined:
    Apr 22, 2022
    Messages:
    46
    Balance:
    327Coins
    Ratings:
    +14 / 0 / -0
    My Motion Simulator:
    3DOF
    hi
    i am starting a project inspired by "DOF Reality Motion Simulator H3"
    i am waiting for the delivery of a wheelchair motor 24v 220w which i hope have couple.

    for the electronic part i am thinking of starting with itb-2,Arduino Uno r3,smc3 and see if the project works and maybe deserves a sabertooh.

    this simulator is delivered with optional steering dumpers
    I do not quite understand the usefulness apart from adding a constraint, this type of shock absorber does not return to this position like a spring.
    [​IMG]
  2. Ads Master

    Ads Master

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

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

    Joined:
    Jul 13, 2014
    Messages:
    18,017
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    129,218Coins
    Ratings:
    +10,068 / 47 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    I suspect the steering dampeners are for load compensation in circumstances where the motors are marginal specs for the rig design.
  4. Jordan Casalini

    Jordan Casalini Member

    Joined:
    Apr 22, 2022
    Messages:
    46
    Balance:
    327Coins
    Ratings:
    +14 / 0 / -0
    My Motion Simulator:
    3DOF
    Thank you for your reply.

    What do you find marginal in the specs?
    Speed 50 cm/s (86 °/s)
    Torque 25 n/m

    On some diy simulators I regularly see springs to "help" the engine.

    I don't quite understand how it works because it will be help to go up but will add additional force to go down?
  5. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

    Joined:
    Jul 13, 2014
    Messages:
    18,017
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    129,218Coins
    Ratings:
    +10,068 / 47 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    There is always a tradeoff between design/performance Vs physics, SimCalc can help understand those compromises: https://www.xsimulator.net/communit...e-linear-speed-and-forces-of-your-design.270/

    Assists can mask fine motion, in addition as gravity/mass assists going down is not really the issue, but rather going up.

    I am not being critical of assists, I created an adjustable heave knee for my compact rig, rather it is all about implementation Vs compromises, particularly on a commercial rig that needs to account for a wide range of user variables.

    In my view Torque 25 n/m for a commercial rig is likely marginal in some circumstances, 35+n/m would likely be better for a full frame rig with knee leverage, particularly for larger users and heavier peripherals.
    • Like Like x 2
  6. GWiz

    GWiz Active Member

    Joined:
    May 12, 2019
    Messages:
    116
    Occupation:
    Dentist
    Location:
    Aberdeenshire, Scotland
    Balance:
    1,018Coins
    Ratings:
    +72 / 0 / -0
    My Motion Simulator:
    6DOF
    The dampeners on the DOFReality H3 are to provide smoothing to mask the effects of backlash on the gears of the gearbox attached to the motor. The H3 uses a universal joint as a pivot point and there is a bit of freeplay when you move past the tipping point. Carefully balancing the weight on the rig apparently helps quite a bit to mitigate this. They have a new gearbox system now that uses a short ball screw moving the lever instead of the current arm on the gearbox design. It apparently works quite well and looks like a clever solution, though presumably you lose some fidelity compared to a more traditional linear actuator.

    As a side note, the mentioned freeplay in the gearing can be a considerable problem. It's not such a big deal for racing sims using small, fast movements as you often won't notice a bit of a wobble, but with flight simulations using a larger and slower motion, it can be very obvious and immersion breaking if the rig doesn't move correctly and smoothly through the whole motion.

    DOFReality also has a 6 DOF version that uses gas struts to provide smoothing and additional lift to help the motors push against gravity.

    Springs are often used for the same purposes - i.e. providing a bit of preload or assisting an underpowered motor.
    • Like Like x 2
    • Agree Agree x 2
  7. Jordan Casalini

    Jordan Casalini Member

    Joined:
    Apr 22, 2022
    Messages:
    46
    Balance:
    327Coins
    Ratings:
    +14 / 0 / -0
    My Motion Simulator:
    3DOF
    Thank you very much for all these explanations, I hope to succeed in having the minimum of Backlash in my assembly.

    the springs seem to me a good solution remains to draw and test I have different springs in stock that can help (bad in calculation)
    Last edited: Apr 30, 2022
  8. Jordan Casalini

    Jordan Casalini Member

    Joined:
    Apr 22, 2022
    Messages:
    46
    Balance:
    327Coins
    Ratings:
    +14 / 0 / -0
    My Motion Simulator:
    3DOF
    hello thank you all for your help.

    currently i waiting for my engines (returned to sender for an unknown reason).
    i continue to analyze the model and make diagrams, i have noticed that the distance between the gimbal and the connecting rod is greater in width than in length.
    I imagine the torque will be greater to move from right to left compared to front to back? Does that seem logical to you compared to a square?

    Insert image IS possible only by URL?

    Thanks
    Last edited: Apr 30, 2022
  9. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

    Joined:
    Jul 13, 2014
    Messages:
    18,017
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    129,218Coins
    Ratings:
    +10,068 / 47 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    There are some initial restrictions on new members, to prevent spam: https://www.xsimulator.net/community/threads/motorcycle-4-dof-motion-sim.16530/page-3#post-228009

    But after 5 posts you can directly upload and insert an image into a post: https://www.xsimulator.net/community/faq/upload-pictures-or-files.81/

    As mentioned in my earlier post SimCalc will help you understand design and related things such as what the torque will be for each axis for a given design and motors:
    • Like Like x 1
  10. Jordan Casalini

    Jordan Casalini Member

    Joined:
    Apr 22, 2022
    Messages:
    46
    Balance:
    327Coins
    Ratings:
    +14 / 0 / -0
    My Motion Simulator:
    3DOF
    ok i understand better thank you.
    I will install simcalc as soon as possible and test the difference in torque between a rectangle and a square
    (a photo would have helped to understand this sentence)

    my question was more to understand if one movement needed more torque than the other

    in the example (rectangle h3) the movement right left is wider so more torque (I suppose)
    I will check this with the software.
    I hope to be able to illustrate my remarks soon.

    concerning the ibt-2 or sabertooh I have heard of the risk of overvoltage or intensité by Dynamo effect of the motor I have great difficulty imagining that even a sudden movement of 120 degrees can provide so much intensity or voltage it IS a guess or a real problem?

    for sabertooh some are installing resistors and on ibt-2 diodes ... do you think it would be better to install diodes?
  11. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

    Joined:
    Jul 13, 2014
    Messages:
    18,017
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    129,218Coins
    Ratings:
    +10,068 / 47 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    The shorter the inherent leverage and motor capacity the more torque required.
  12. Jordan Casalini

    Jordan Casalini Member

    Joined:
    Apr 22, 2022
    Messages:
    46
    Balance:
    327Coins
    Ratings:
    +14 / 0 / -0
    My Motion Simulator:
    3DOF
    ok so the left right axis is wider in order to relieve the engines
    it may seem logical that the constraint is greater on this axis compared to front rear the weight is perhaps better distributed
  13. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

    Joined:
    Jul 13, 2014
    Messages:
    18,017
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    129,218Coins
    Ratings:
    +10,068 / 47 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    Generically speaking the front/rear distribution is favored in terms of inherent design leverage. But both axis have to be capable of meeting the designed mass and performance design objectives.
  14. Jordan Casalini

    Jordan Casalini Member

    Joined:
    Apr 22, 2022
    Messages:
    46
    Balance:
    327Coins
    Ratings:
    +14 / 0 / -0
    My Motion Simulator:
    3DOF
    hello

    I come back after having finished my first engine.
    (If you have any questions about the modification ask.)
    I tested it with a weight after one meter and an ampermeter.

    Your predictions what is the torque of this engine? (24v 220w 150rpm)

    Attached Files:

  15. Jordan Casalini

    Jordan Casalini Member

    Joined:
    Apr 22, 2022
    Messages:
    46
    Balance:
    327Coins
    Ratings:
    +14 / 0 / -0
    My Motion Simulator:
    3DOF
    hello,
    I'll put an end to the suspense...
    I was very shocked at the weight that this motor lifted and so easily.

    I started the test at 12v, it lifted 5.5 kg at 75 rpm and 11 kg at 150 rpm at 24 v...
    before buy second-hand motors I looked at the motors sold for simulator from 35nm to 65nm and a speed around 50 rpm. (24v)

    Is it better to use it in 12v so that it is closer to the parameters of engines sold for simulator (75rpm 55nm) or the fact that it is very strong and fast is better?
  16. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

    Joined:
    Jul 13, 2014
    Messages:
    18,017
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    129,218Coins
    Ratings:
    +10,068 / 47 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    It is more a question of getting 24v controller and PSU, that takes full advantage of the motors you have, though you could use 12v if you wanted to. The rest comes down to suitable design choices..
    • Like Like x 1
  17. Jordan Casalini

    Jordan Casalini Member

    Joined:
    Apr 22, 2022
    Messages:
    46
    Balance:
    327Coins
    Ratings:
    +14 / 0 / -0
    My Motion Simulator:
    3DOF
    Hi
    I heard that the torque is never too much.
    but that the speed (150rpm at 24v) can be a difficulty in setting (pid, setpoint overrun)

    I am looking for information on this subject
    I still have to learn the software part, I don't haven't started the chassis yet, I'm gathering the parts and preparing the future engines
  18. MarkusB

    MarkusB Well-Known Member Gold Contributor

    Joined:
    Jun 30, 2015
    Messages:
    556
    Location:
    Germany
    Balance:
    4,198Coins
    Ratings:
    +581 / 2 / -0
    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, Motion platform
    I can confirm this.

    I am using very similar wheel chair motors and definitely recommend using 24V.
    Some time ago one of my two 12V power supplies stopped working, so that the motors were running with only 12V. The result was that they were much less responsive.

    I don't see a speed of 150rpm as an issue. A high speed just means that the rig is responsive. If you encounter too hard movements, you can still apply smoothing filters.
    • Like Like x 1
  19. Jordan Casalini

    Jordan Casalini Member

    Joined:
    Apr 22, 2022
    Messages:
    46
    Balance:
    327Coins
    Ratings:
    +14 / 0 / -0
    My Motion Simulator:
    3DOF
    hello,
    thank you very much, that's reassuring.
    have you shared your work here?
    I started to make a model of the 2dof part (cooperative engine) based on existing diagrams.
    The idea being to find the placement before welding the chassis.

    Compress_20220512_165452_2651.jpg
  20. Jordan Casalini

    Jordan Casalini Member

    Joined:
    Apr 22, 2022
    Messages:
    46
    Balance:
    327Coins
    Ratings:
    +14 / 0 / -0
    My Motion Simulator:
    3DOF
    the radius of the circle is 30 cm and the middle between the motor shaft and the crank (between 4.5 cm and 6 cm) is placed at 45 degrees.
    the gimbal is at the center of the circle.
    Compress_20220512_182756_6294.jpg
  21. MarkusB

    MarkusB Well-Known Member Gold Contributor

    Joined:
    Jun 30, 2015
    Messages:
    556
    Location:
    Germany
    Balance:
    4,198Coins
    Ratings:
    +581 / 2 / -0
    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, Motion platform
    Yes, here is my build thread:
    My 3 DOF motion-enhanced G-Seat
    • Like Like x 2