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Question Hydraulic 6DOF Stewart Platform Control Hardware?

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by Khaotic, Oct 15, 2018.

  1. Khaotic

    Khaotic New Member

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    Hi everyone!

    I have recently acquired a large 6DOF Stewart motion platform on eBay (For a total of $500AU!). It apparently originally came from an arcade where it was paired with a cinema screen with a total of 9 seats on top. Unfortunately, through the changing of hands, the computer that ran the software is no longer with it, and it only has the control board. It looks to have 6 solenoids to control the hydraulic rams, and some chinese board that runs the solenoids. The board looks to have a 4 pin input that is labelled COM, so I am assuming it communicates via some form of UART to send control signals, but I have no idea what the protocol is. I have tried reaching out to the original manufacturer of the sim as well as the control board and they no longer have anyone working there who is familiar with the system.

    Is anyone familiar with this sim/control board, and if not, what are my options for replacing the control board with another controller that will work with the hydraulics?

    Photos are attached below of the sim.

    Cheers,
    Khaotic

    44028483_258353688217491_6136083264554663936_n.jpg 44033745_458204521368834_2381890443186012160_n.jpg 44041482_311736142746951_1475876609742340096_n.jpg 44041566_520487548377607_5950518828868829184_n.jpg 44045273_515776462228782_4170956574958813184_n.jpg 44054589_311004336363369_2063718621653237760_n.jpg 44065130_304299073633384_7341298169243762688_n.jpg 44076955_530488920749161_7647623465951821824_n.jpg 44110196_1385315158265749_513418565202739200_n.jpg 44154293_2159399074381456_5864708521915842560_n.jpg 44168598_245334892997616_6184305490906841088_n.jpg
  2. noorbeast

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

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  3. AussieSim

    AussieSim Member

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  4. Khaotic

    Khaotic New Member

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    Thanks guys. Shame that forum thread ended in him selling it before he got it working! I've been looking at the AMC1280USB controller and trying to figure out whether I will be able to get it to control the hydraulic solenoids. Not sure the exact signals required to control them and whether I'll need to use an Arduino to sit in the middle. Have you guys used that controller before?
  5. prodigy

    prodigy Burning revs

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    Maybe the creator of the AMC1280 can answer you? @Thanos
  6. noorbeast

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

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    The AMC1280USB is a very flexible controller and its creator @Thanos has assisted many to jailbreak closed system motion sims, so well worth considering.
  7. Khaotic

    Khaotic New Member

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    So I've spent a bit more time looking over the existing control board and I have a pretty good idea of how it is working and how I could add the AMC1280USB. I have annotated the board below:

    control_board.jpg

    Firstly, the red chip is some sort of microprocessor with unknown firmware on it. The 4 pin yellow input is the COM input, where I assume the serial connection to the controlling computer comes in and is processed by the microprocessor. The cyan wires connect to the 6 variable resistor sensors attached to the hydraulic rams to give position information. The big magenta block contains 12 24V MOSFETs that drive the 6 pairs of solenoids on the hydraulic manifold, which go out via the two magenta connectors. The orange block of MOSFETs connect to 3 valves that let air through to little rubber pipes that whip the user's feet.

    What I am thinking is, I could be able to desolder the microcontroller off the board and replace it with the AMC1280USB, running its 5V outputs directly to the pins under where the micro was to directly the control the solenoids. My only concern is I don't think the AMC currently supports 12 outputs, so I may need to put a NOT gate on each of the outputs to the corresponding paired solenoid. If @Thanos is around, I'd love to hear if he thinks that would work!
  8. Thanos

    Thanos Active Member

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    The AMC1280USB, has 12 digital outputs for direction, so you could connect the solenoids there. The position sensors are also connected in the 6 inputs on the AMC1280USB. The only thing missing is the speed. I don't think this platform supports speed control. It will require to setup the AMC1280USB with low "step" setting to simulate the missing speed control, so it will switch its direction pins on and off proportional to the feedback sensors to approximate the position.

    I believe it can be done if you use the AMC1280USB 5V signals to bypass that control chip.

    Thanks
    Thanos
    • Informative Informative x 2
  9. Khaotic

    Khaotic New Member

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    Awesome, thanks @Thanos! When do you think you'll be getting another batch of AMC1280USBs made? I've jumped on the wait list, I'm just a bit impatient! :grin
  10. Thanos

    Thanos Active Member

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    I'm restocking parts currently, some parts are getting hard to get and take longer to ship and arrive to USA

    Right now the waitlist on Tindie is 5 people and growing each day...
    Last edited by a moderator: Oct 22, 2018
  11. Thanos

    Thanos Active Member

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    Last edited by a moderator: Oct 22, 2018
  12. Khaotic

    Khaotic New Member

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    Looking forward to getting my hands on one of the controllers @Thanos! Thanks for the work you're doing on them!
    Last edited by a moderator: Oct 22, 2018
  13. Khaotic

    Khaotic New Member

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    Hi @Thanos. I recently received my AMC1280USB and I have started connecting it up to my motion simulator and I have a few questions for you. I have removed the old micro off the board and mapped out the pins on the footprint to each of the solenoids. The control signals for the solenoids appear to be triggered when the input pins are pulled down from 5v to gnd. I have found a CMOS inverter that I should be able to use if the digital outputs on the AMC are at 5V when trying to trigger the solenoid (TI CD74HC04E). How do I set the AMC up to use 2 channels for each ram, one for up and one for down? And how do I set the low "step" setting to simulate the missing speed control?

    Cheers,
    Khaotic
  14. Thanos

    Thanos Active Member

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    First, you need to setup the board in the menu, the Input for Analog with 10bit, 180.
    Then setup the Output for Analog 8bit, and bi-directional.

    Second, did you connect the analog position sensors to the analog inputs of the AMC?
    (A1, A2, A3, A4, A5 and A6), I assume the position feedback sensors on your platform are linear potentiometers, right? Can you show them here?

    Based on the feedback on the sensors, the AMC will enable each of the two digital direction outputs, so each should be connected to the solenoid for up and down. When the position sensor is on target, both digital outputs are disabled (0v). The gap for these two outputs to be off, is small, but you can increase it if you increase the Min Speed parameter (i think it goes up to 14).

    Also decrease the PID settings down to:
    P= 10, I=0, D=0, for all motors.

    Then, to create virtual steps for controlling the speed, try to decrease the STEP parameter, that is located under the 6DOF home position menu item. Set the step down to 10.

    Give it a try, if the actuators move all the way to one direction, you may need to reverse the connection for the two digital direction pairs for the actuator to get the correct direction.

    Thanks
    Thanos
  15. Khaotic

    Khaotic New Member

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    Awesome, that's super useful info. Will give it a try soonish and let you know how we go! The sensors are these linear potentiometers, which already operate from 0-5V from my testing, so they should just work out of the box.

    [​IMG]

    Fingers crossed we get it working and don't kill someone in the process! :D
  16. Thanos

    Thanos Active Member

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    Connect one linear potentiometer and one set of solenoid first to try one actuator... dont try all together!!
  17. Khaotic

    Khaotic New Member

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    Yeah that's the plan. I have removed one of the linear pots from the side of the rams so I can manually adjust it, and the hydraulics run on a separate circuit from the solenoids, so I can operate the solenoids without the 3 phase hydraulic pump turned on.