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[in progress] 6DOF compact and small footprint

Discussion in 'DIY Motion Simulator Projects' started by Rens, Sep 5, 2020.

  1. Gadget999

    Gadget999 Well-Known Member

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    I had a read of the manual and it states 0 to 255 as the output

    However I think it may be refering to a binary output example which is charachters 0 to 255

    I might do some comport sniffing and see if the resolution really can go to 16 bit or if it just calculates the position to a higher number.

    @youbuddy what is the max resolution and what resolution does Rf2 send ?
  2. Thanos

    Thanos Building the Future one AC Servo at a time... or 6

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    RF2 output is 32bit, simtools output can be 16bit, arduino feedback loop resolution 8bit to 10bit...
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  3. Rens

    Rens Member

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    The Due, Zero and MKR Family boards have 12-bit ADC capabilities that can be accessed by changing the resolution to 12. This will return values from analogRead() between 0 and 4095.

    There are possibilities to get 16 resolution on pins 9 and 10 but it's more complicated.
  4. Thanos

    Thanos Building the Future one AC Servo at a time... or 6

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    yeah, be aware... these are 3.3v microcontrollers... you will need additional level shifters circuits...
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  5. Rens

    Rens Member

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    I have been asking 2 companies about their suggestion for a PSU in regards to my motors and setup. Got response from one and they highly recommended to use 2x SDR-960-24 Mean Well, and use 1 for 3 motors. They are quite expensive though ($247 each), but I think it's not good to save on PSU(s). I couldn't find any videos on this PSU to see how much sound it produces. It's a rather compact PSU: 5.91" L x 4.33" W x 4.93" H (150.0mm x 110.0mm x 125.2mm). What do you think about this PSU? It also has Control pins, (DC OK Relay Contact can be used to connect Emergency button I guess?).

    control-pins-dc-ok-relay-contact.JPG

    control-pins-dc-ok-relay-contact-2.JPG


    Below is a diagram on how it would look like for 3 motors circuit. I am planning on using a single arduino uno for now (I should have just about the right amount of Analog, PWM and direction pins?). At least I can do some testing with it, and later upgrade to a different board.

    I already purchase all parts except for the PSU.

    circuit-diagram.png
  6. Gadget999

    Gadget999 Well-Known Member

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    are you sure 220w is enough power ?
  7. Rens

    Rens Member

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    Already ordered those so it has to be. They recommended me those motors based on 150kg weight to lift. If it's not enough it would be unfortunate. So you think it's not enough? Let's hope I can prove you wrong :popcorn
  8. Rens

    Rens Member

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    Also got reply from other company today and they recommended a single PSU (1500W). Which is great to keep things simple. I created a more detailed circuit drawing with this new PSU and a fuse box in front of the motor driver. I should receive motor drivers and shunt regulators tomorrow, which means I can start playing/testing with code a little bit. :)

    circuit-diagram-v2.jpg
  9. byAGM

    byAGM New Member

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    Excuse me, I was afraid of that too. I'm from Spain I have 4.6kw at home so I was afraid of "750x6= 4500w only motors?" BUT a few months ago I asked to Christopher Knauf to make a video of the live consumption of the servos: I think it will help you:
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  10. Rens

    Rens Member

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    Just received motor drivers and shunt regulators today. Now I can start testing with a motor I have laying around. :D
    IMG_20200916_140547.jpg
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  11. Rens

    Rens Member

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    Just finished soldering the connector blocks to the boards. Long time ago that I soldered, but it should do the trick :p

    IMG_20200916_162052.jpg
  12. Thanos

    Thanos Building the Future one AC Servo at a time... or 6

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    My Motion Simulator:
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    Are you sure these screw terminals can fit AWG 8 size wires?? AWG8 = 3.3mm diameter by the way..

    The datasheet for these screw terminals mention that you can use only up to AWG 16 wiring, meaning should not load these thinner wires over 13Amp ...

    https://media.digikey.com/pdf/Data Sheets/Phoenix Contact PDFs/1729018.pdf


    Just saying... :nerd
    Last edited: Sep 16, 2020
  13. Rens

    Rens Member

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    @Thanos, I am not planning on exceeding the 13A, those motor drivers are rated 13A. 8 AWG will definitely not fit those sockets. :p Right now I have fitted 16 AWG wire to test with a 24v motor I had laying around. That motor only draws 1.8A peak at around 18v.
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  14. SeatTime

    SeatTime Well-Known Member

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    IMO I would solder the high DC current cables directly to the card instead of using those screw terminals and then use proper high current connectors. No way you will be drawing 1.8A peak once those motors have a realistic load/inertia on them. I use to regularly trip two 200 amp DC circuit breakers on my Stewart platform when the sim was going full tilt (had to change to slow blow fuses).
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  15. Thanos

    Thanos Building the Future one AC Servo at a time... or 6

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    1.8A is not stall current... stall current is probably 20 times more, also called short circuit... stall is common when you change direction of the motor really fast, because of inertia.
  16. Rens

    Rens Member

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    @Thanos, @SeatTime Thank you both for your input and for clarifying this. I will probably will have no other option than soldering bigger gauge wires directly onto the board then. But I think the maximum gauge to solder directly onto the board would be 12 (maybe 10 if lucky?). Based on the feedback I have a question:
    The motor drivers are rated 13A so I shouldn't exceed this anyways right? You say that the stall current of the motors would be much higher than that. Wouldn't that kill the motor driver?

    Yesterday I have been playing around with that DC motor I had laying around, wrote some code and tuned PID. It seems to be working quite well. I have also configured simtools, and all looking good code/settings wise. It will take awhile before I receive the motors though. I will wait until I receive both the PSU and motors and then continue with the project.
  17. SeatTime

    SeatTime Well-Known Member

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    Depends what the 13A rating is referring to - continuous, or peak. You don't see these big currents continuously. Good motor drivers should handle it OK, although often the power supplies can trip, which is why I also had a big battery to smooth things out (actually I ended up only running the sim on batteries - as they were constantly charged through the day by a solar array.
  18. Rens

    Rens Member

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    @SeatTime, they are rated 30A peak (10 sec.) and 13A continuous.
  19. Rens

    Rens Member

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    Anyways I ordered some other terminal sockets which should fit 10 AWG wires and should fit on the board. For both shunts and drivers. You can see in the picture how I am planning my layout. This way it should be compact enough and wiring shouldn't become a mess. Wires used in picture for the time being are 16 AWG. The terminals do fit 10 AWG, I tested that. :)

    16004524114372860011051175293769.jpg
  20. Rens

    Rens Member

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    Today I made some good progress on my "cabling" layout. The PSU will be fitted below the plexiglass (which I had laying around somewher) . Cables will go through some holes in the glass, and then directly into the driver and shunt. The DIR and PWM will also go through the glass back to the arduino board which sits below the plexiglass, at least that was my initial thought. But it might be easier to fit it on top of the plexiglass.

    As you can see I have placed the shunt above the driver (I had to drill bigger holes into it).

    I also might add some fans on the right side to blow hot air away. Will have to see about that. No idea if it's required or not. In that case the arduino might be better placed below. Anyway here are some pictures :cheers

    IMG_20200919_191739.jpg IMG_20200919_191734.jpg IMG_20200919_210735.jpg IMG_20200919_212732.jpg IMG_20200919_212735.jpg IMG_20200919_212741.jpg IMG_20200919_212751.jpg IMG_20200919_212803.jpg IMG_20200919_212813.jpg
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