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Showroom Compact AC Servo 6DOF Rotary Stewart platform

Discussion in 'DIY Motion Simulator Projects' started by knaufinator, May 26, 2020.

  1. FeidhlimLee

    FeidhlimLee New Member

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    Thank you so much for tutoring me, sir! I appreciate it so much. By the way, here is China and If you possibly need me to purchase anything for you I would be very happy to help.
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  2. FeidhlimLee

    FeidhlimLee New Member

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    one more question sir, does the servo driver needs to have Serial Communications capability.
  3. knaufinator

    knaufinator Active Member

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    My Motion Simulator:
    AC motor, 6DOF
    The way this design communicates is through the db25 connector on the servo driver, I understand there are modules you can get for like MBUS? ,.. i think it was called,.. that would allow for a greater level of communications... but no... I do not use this... only the standard db25 - using the direction/position inputs
  4. FeidhlimLee

    FeidhlimLee New Member

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    Thank you very much sir
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  5. FeidhlimLee

    FeidhlimLee New Member

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    Sir, here I encountered this issue. I tried all the ways and could not find 3.3v-5v level shifter like yours, same as 12v stepup regulator. I wonder if there is any substitute.
  6. knaufinator

    knaufinator Active Member

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    My Motion Simulator:
    AC motor, 6DOF
    The 3.3-5v shifters are sold under several names, here are 3 that I found. I just search for 3.3v -5v 8 channel,. look for the red color...
    https://www.aliexpress.com/item/32916611951.html?spm=a2g0o.productlist.0.0.4b935d09YSrryY&algo_pvid=fd529d4e-383b-44e4-8853-006ae8b5471a&algo_exp_id=fd529d4e-383b-44e4-8853-006ae8b5471a-1&pdp_ext_f={"sku_id":"65905787890"}

    amazon.com/gp/product/B075PSB71D

    https://www.ebay.com/itm/124928766690?epid=19009270602&_trkparms=ispr=1&hash=item1d1655b2e2:g:lu8AAOSwLgxhVwvq&amdata=enc:AQAGAAACoPYe5NmHp%2B2JMhMi7yxGiTJkPrKr5t53CooMSQt2orsSxXDXcCydCuSj2Tq2S%2F3Gnv1AuFBwEbb4mn37Tqe%2FvblRRUatmfIk2oxOvBxCYmXm6TnOBGA4W1RmjwRs0eUXxudoXvAhxJXcZkfPHDG0R1xJ5k0Ym8ZFk6jSGEBNRrCgoKwPQanhinGjrhOJUZTKW4vvvOl5cDtjQ4L8RHRV0%2BQjS3QDbE9BbIG7u1%2Bwc674uJTzzXcnTryVxXQCXZTFpVNOfQBv21qurn4oqFPxgeNqYi%2B59dyQmXnkGrqm%2FH%2BdfcunobIJRE%2FT4dsW2WNpbNIpzAR8pLmPheg6lOkLElBD4M6BjWo7t%2FO%2B1Ob0H7JlpA6WYoHAgiX0tV36q%2Fv6qZLAi0VlH1TPtqBZoSJ%2BY5Q0EFgAF%2BXHMBCueNsQYUJbi1ZuSktAde2QKFicMlV62RR7BBjkZ0E9gaQymBkTqB28oVSX0DtcyJyIRPod3W1YuLT6mn8x7j5Ol3WvPZg161h58eazqsr7kfJ1KnTpbZU%2B1luNf4PGBssn%2F4Mn30rIo861W32Bd6xuz1LUmJ7PzjolVPzXK%2Bmds2WzN75IjK%2FNIhxZx5R9EuNVA%2BBicpSkk33Gwbqgk6cseJO7VRupxPBUsgUBmmpL3mtsFLv%2Brslc8UnhjBp9RK4JCcEuKEh1s9B6yyiNSH%2BCK5wO9W3moiUXFRnnPBmCR0pjMNsJ%2FetQQ8Q7eWnUwsS5YvamosnUBSCg6lIvKYuN3iDsHzY6%2BdD1tUmRS2yW0XHLhPM%2FS%2BuEtXm3lyjSzlyWPzTzvDslP2Bxv4igp6L5d2c6Xhaij53GVXIqNNcutrHdj5nle4en6nGUq%2BhpbqKSrI5HNPX5%2FvsL2lMWSRQdAX1kv%2BQGbw%3D%3D|clp:2334524|tkp:BFBM0tehiZxf

    As for the 12 volt step up converter,... I used pololu for allot of my racing drone stuff, so I had them laying around ... the goal is to provide a 12v source to one of the pins given a 5v source and ground. .. it uses very little current, it is for the hall sensors. I know other builders of this platform have sourced different parts such as this one, and gotten it to work. I will reach out and see what they used.

    I used this one, I realize it may not be available to ship to all regions...
    https://www.pololu.com/product/2117
    Last edited: Nov 2, 2021
  7. sallerding

    sallerding New Member

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    My Motion Simulator:
    6DOF
    Great job! Curious to know whether the 1/4” steel plate (approx 6mm) has been sufficient for the gearbox and motors with little movement/flex?
    Last edited by a moderator: Nov 6, 2021
  8. knaufinator

    knaufinator Active Member

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    My Motion Simulator:
    AC motor, 6DOF
    Great question , The 1/2 inch plate does flex slightly with larger riders, and at full reaction speed. Not enough flex to cause distortions in the motion geometry. The 1/4 motor mounts with the angle supports are sufficient as well,..(for my weight).. It does not flex with sub 200lb riders as far as I can tell. it would only take a few supports under the plate in order to tame that base plate flex. its so insignificant I wont do it unless I have the plate upside down and near my welder.... so maybe if I move?.. ...
    Last edited: Nov 6, 2021
  9. sallerding

    sallerding New Member

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    My Motion Simulator:
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    Thx for the quick answer. Have already built my rig frame but machining the gear mounts using motion 4sims rig is proving expensive and slightly complicated (15mm plate with milled recess for gear mount to 6mm) secured to upper frame. Was seeing if an alternative might work with my rig. Perhaps a version of yours attached to a light upper frame would also help to provide stability, or your suggestion of a base . Thx again. Will give it some thought. Reason being is that I will be looking to support a larger weight (seat rig) on the upper platform
  10. sallerding

    sallerding New Member

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    My Motion Simulator:
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    Here’s the 3d printed mount created

    Attached Files:

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  11. tu xiao mi

    tu xiao mi Member Gold Contributor

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    My Motion Simulator:
    Arduino, 6DOF
    when you set up the axis3, does only the servo 3 move?
  12. knaufinator

    knaufinator Active Member

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    My Motion Simulator:
    AC motor, 6DOF
    No, each "Axis" is a DOF. Think of it as a representation of a 3d object in space. you need 6 values to define it.

    surge,sway, heave,roll, pitch,yaw, the rig will then, by using its own math.... figure out how to get there. any one value in any of those spots,... will cause ALL motors to move,.. ... in order get the platform to the desired position.
    Last edited: Nov 8, 2021
  13. tu xiao mi

    tu xiao mi Member Gold Contributor

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    My Motion Simulator:
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    If I change the diameter of the circle to 90 cm, do I need to modify the size between the connection points?
  14. tu xiao mi

    tu xiao mi Member Gold Contributor

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    My Motion Simulator:
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    and what's the Theta_R Theta_S Theta_P in the excel?
  15. knaufinator

    knaufinator Active Member

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    My Motion Simulator:
    AC motor, 6DOF
    no, as long as the machine can physically move its arms without hitting stuff,...

    This one took trial and error to figure out - change the number, and see what changes in the visualization

    Theta_R = Platform Joint Angle (β) = this is the angle between two connecting points on the upper chassis. the angle is measured from the center of the upper circle. .. the connecting points all exist on the same circle.

    Theta_S = Angle at which the servo arm lies(Degrees) = this is the position of the arm/motor. This tells the algorithm what way the motors/swing arms are pointing. change them,... and the visualization also changes, you may need to zoom in.

    Theta_P = Base Servo Joint Angle (α) = I believe this on is the angle between two servos along their axis, from the center of the base circle.
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  16. tu xiao mi

    tu xiao mi Member Gold Contributor

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    My Motion Simulator:
    Arduino, 6DOF
    Theta_S = Angle at which the servo arm lies(Degrees) = this is the position of the arm/motor. This tells the algorithm what way the motors/swing arms are pointing. change them,... and the visualization also changes, you may need to zoom in.

    I can not understand this angle
  17. tu xiao mi

    tu xiao mi Member Gold Contributor

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    My Motion Simulator:
    Arduino, 6DOF
    upload_2021-11-10_23-12-6.png
    and if the distance of two points is 14cm, the angle is 20 degree
  18. tu xiao mi

    tu xiao mi Member Gold Contributor

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    My Motion Simulator:
    Arduino, 6DOF
    upload_2021-11-11_0-21-29.png
    and in the code the theta_r is 10
  19. tu xiao mi

    tu xiao mi Member Gold Contributor

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    My Motion Simulator:
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    and what's the platformHeight? the chassis height from floor?
  20. tu xiao mi

    tu xiao mi Member Gold Contributor

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    My Motion Simulator:
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    and do you use washout algorithm