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Kermit Kong's 6DOF Project

Discussion in 'DIY Motion Simulator Projects' started by kermitkong, Jun 15, 2016.

  1. SilentChill

    SilentChill Problem Maker SimTools 2.0 Beta Tester

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    My Motion Simulator:
    DC motor, Arduino, Motion platform, 6DOF
    Just use headphones cant hear nothing then :)
  2. kermitkong

    kermitkong Active Member Gold Contributor

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    My Motion Simulator:
    DC motor, Motion platform, 6DOF

    Yes noise is normal, but I had an issue where the gear part contacted the housing which made the noise. But it is fixed now.

    Only have the normal ball bearings noise now.
    Last edited: Dec 11, 2017
  3. Doon1

    Doon1 Member

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    I'm wondering if it would be worth the effort to install shaft seals and o-rings to seal up the tube and then fill it with mineral oil to absorb the noise.
    Is that a continuous recirculating ball type screw?
  4. thecure

    thecure New Member

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    nice i wait the building plan ;)
  5. Limongi

    Limongi Member

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    Hi Kermit, wonderful build. How did this choice work out for you? I'm trying to brainstorm a parts list and design for a set of compact actuators and would love this solution if you recommend it.
  6. kermitkong

    kermitkong Active Member Gold Contributor

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    My Motion Simulator:
    DC motor, Motion platform, 6DOF
    hi @Limongi

    the magnetopots parts work good so far, testing time until now is about 2h. no issues found.
    so i would say the magnetopot is definitely a possible good option as i think.
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  7. kermitkong

    kermitkong Active Member Gold Contributor

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    My Motion Simulator:
    DC motor, Motion platform, 6DOF
    Hello guys,

    hereby i would like to share my actuator and motionseat design. This design was inspired by Hoddems actuator design.
    complete_Actuator.JPG
    I created a OneDrive folder, please feel free and download it if you are interest it.
    The Dataset also includes to Bill-Of-Material (BOM) and a wiring diagram of the motion-seat as well.
    if you have any question, please let me know.
    https://1drv.ms/f/s!AmCwooBbjonByhp8Kd3xmfgRgRxl
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    Last edited: Dec 19, 2017
  8. kermitkong

    kermitkong Active Member Gold Contributor

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    My Motion Simulator:
    DC motor, Motion platform, 6DOF
    Quick important note here !
    After 20h of testing

    The magneto pots has a hysteresis which meight be affect the smooth motion (depending which resolution is needed).
    For car racing game this should be ok.
    For elite dangerous which need a super smooth back and force movement this is a drawback!

    I will check out alternatives e.g. soft-pots which not have the hysteresis effect.

    Will come with a solution soon.
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  9. kermitkong

    kermitkong Active Member Gold Contributor

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    My Motion Simulator:
    DC motor, Motion platform, 6DOF
    just another change for my actuators.
    this is only meaningful for elite dangerous or flight simulators in general.

    i reduced the gear ratio from 1:1 to 2:1.
    Before i had 5mm shaft-travel per motor axis turn.
    now i have 2.5mm shaft-travel per motor axis turn.
    the result should be more smoothness, less jerking on the platform.

    The actuator speed is reduced to about 110mm/sec. (before 220mm/sec.)
    This is great for flight simulation, but could be slightly too slow for car racing simulation.

    anyway both option fits into the construction. the 1:1 and the 2:1 setup.
    also added a belt-tightener as you can see in the picture.
    gear-ratio.JPG
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    Last edited: Jan 22, 2018
  10. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator SimTools 2.0 Beta Tester

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    My Motion Simulator:
    3DOF, DC motor, JRK
    Did you try lowering the Main % in Game Manager before the gear ratio change, as that adds global smoothing.
  11. fuad

    fuad New Member Gold Contributor

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    nice work ....
    can you put the diagram and components for the battery connection. do i connect it in parallel with bridge or add some thing in between.
  12. kermitkong

    kermitkong Active Member Gold Contributor

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    My Motion Simulator:
    DC motor, Motion platform, 6DOF

    Hi @fuad ,

    there're two version for the regen energy buffer available.
    This is the version which discharge the battery over time to about 50% capacity.
    This give the smaller battery enough capacity to buffer the energy which comes back from the motors.
    [​IMG]

    this is a simplified circuit. This configuration has an drop-voltage over D1 which ecceptable low.
    This Version needs more capacity for the batteries compared to the previous to be efficient.

    upload_2018-1-25_8-5-6.png
  13. kermitkong

    kermitkong Active Member Gold Contributor

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    hi @noorbeast

    yes, i did
    the problem is more on the physical side.
    i use a softpod with 500m length, this is great because give the system enough physical resolution in terms of the feedback loop.

    One of the issue here is, that the PWM resolution is relativly low (10bit), usable resolution is 9bit due to the hysteresis filter (deadzone filter) i need to make the actuator silent when its in the hold position.:think

    so 9 bit means 512 steps. which is about 1mm travel per PWM step.
    This means the highest best resolution is 512 which will result into a smallest travel of 1mm.:(

    This is also because of this design. I have an linear actuator, without a gearbox to reduce speed and increase physical resolution.
    In a classical servo-lever/gearbox design this resulution issue is not happen at all because of the gearbox ratio 30:1 to 60:1.

    back to this issue on my Design, so 1mm movement is quite a notable movement on the chair. this relatively low physical resolution in the movement, reduce the perceived smoothness in chair-movement quite significantly.:mad:

    on th other hand the it is quite difficuilt for a DC motor driver (includes the PID feedback loop) to drive the motor to move less than one turn, this is due to the physical design inside the DC-motor. (overshot effect/magnetization reload). The Motor-design also affect the physical resolution of the actuator movement.

    in my case, one turn of the motor is about 5mm travel on the actuator (1:1 gear ratio).
    1/2 turn about is controlable, less than about 1/2 turn seems to be impossible in my design currently. The new gear-ratio will reduce the smallest travel on the axis of the actuator-shaft by factor 2. (change from 1:1 to 2:1). Theoretically down to 1/4 turn.


    i decided to change the gear ratio from 1:1 to 2:1 of the beltdrive, that means the physical resolution increased by factor 2, smallest movment will be about 0.5 (electrically) and 1 mm (physically), i guess this is nice.:)

    for sure, for any car raycing simultion this is not an issue at all. but for flight simulation like elite dangerous where i'm falling in love with, it is really important i learnt to have a smooooth movement.:D
    Last edited: Jan 26, 2018
  14. fuad

    fuad New Member Gold Contributor

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    @kermitkong thank you very helpful
  15. fuad

    fuad New Member Gold Contributor

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    HI @kermitkong i have done the second option but with a sight change since i have rectifier in hand i used it instead of the Diode you provided in your design. kindly check the attached diagram and advice. note i will double the IBT h-Bridge since they cutoff when i use 1 and my motors are 350W they draw lots of amps.... i have tried this solution and it works....
    thank you
    rec diagram.jpg
  16. thecure

    thecure New Member

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    It's possible to use a same circuit whit battery who have 45 A ?

    Attached Files:

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  17. kermitkong

    kermitkong Active Member Gold Contributor

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    hi @thecure

    thats possible, but makes no difference functional wise.

    if you expect a benifit from the larger batteries (more capacity) i would recommend to use the 2nd circuit option.
    This circuit option give you the benefit to use the battery as a buffer to save powersupplies for over current peaks.
    In this case larger batteries like 45A/h capacity is better than lower e.g. 2.4A/h capacity.
    [​IMG]
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  18. kermitkong

    kermitkong Active Member Gold Contributor

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    My Motion Simulator:
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    hi looks good so far, but theres on issue !!!!

    the power supply deliver AC12V*1.414 = DC16.9V that too much to charge the battery.
    The typical charging voltage is 14.5V to 14.7V

    so you have to reduce the voltage. maybe use some diodes to drop the voltage down to about 14.5V ???????

    Best,
    Kermit
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  19. thecure

    thecure New Member

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    TKS SO MUCH.....i have another questiom.....i have four motor...can i use your circuit ....because absorbe 1400 w..in full work..tks
  20. kermitkong

    kermitkong Active Member Gold Contributor

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    My Motion Simulator:
    DC motor, Motion platform, 6DOF
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