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[in progress] 6DOF compact and small footprint

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

  1. Rens

    Rens Member

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    You are right about that, but because of it I will probably use smaller levers too. I received quote from sunrise motors $100 each, with shipping to netherlands total of $255 for shipping. Gearbox and shaft are included.
  2. adgun

    adgun Active Member

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    Nice to start with.
    If you got the feefer you allways can go better!
    Mag ik vragen waar je woont.
    Ad Den Bosch
  3. Thanos

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

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    Funny, because I can run six of these 750watt servos on single phase 110v 15A fuse without any problems. You see these servomotors are really efficient and the 750watt rating is the max peak draw at 300% of its torque rating...
  4. adgun

    adgun Active Member

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    I didnt know that.
    I had in mine mind 2.4NM at 3000 rpm rated power
  5. Thanos

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

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    Yes, the 2.4Nm torque is at 100% torque on these servomotors, they can deliver up to 7.2Nm on peak torque (300%). And they can deliver same torque depending on the load, across any RPM speed they are commanded to have. From 0RPM up to 3000RPM.
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  6. adgun

    adgun Active Member

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    Do they have soft current limiting?
  7. Thanos

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

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    Yes, you can limit max RPM and Max torque levels if you want to ensure it won't go over a specified power rating.
  8. Rens

    Rens Member

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    @adgun Gelderland (ten oost van Arnhem vlakbij de Duitse grens).

    I am now shopping for potentiometer and motor driver. The motor draws 24v at 220w. I read about the benefits of an Hall effect sensor and am considering it over the regular potentiometer method. However from the wikipedia page I do not understand what they mean with:

    "Hall effect sensors provide much lower measuring accuracy than fluxgate magnetometers or magnetoresistance-based sensors. Moreover, Hall effect sensors drift significantly, requiring compensation."

    Perhaps one of you more experienced guys know what this means? @noorbeast, @Thanos, @T R Para, @accelero, @adgun, @Gadget999

    When I google for "Hall effect sensors" there isn't any good sites nearby that sell these, only found two really and they both sell the exact same one for decent price. It also appeared to me that 180 degree vs 360 degree price didn't matter so I guess I can go for the 360 continuous, might become useful for other projects too.

    The Hall effect sensors I am considering:
    https://www.digikey.com/product-detail/en/tt-electronics-bi/6127V1A360L-5FS/987-1393-ND/2620662

    The motor drivers I am considering are:
    1) Cytron 10A 5-30 V Dual Channel DC Motor Driver - https://www.robotshop.com/nl/nl/cytron-10a-5-30-v-dual-channel-dc-motor-driver.html
    30A peak (10 sec)

    cytron-10A-5-30V.JPG

    2) 50A Dual-Channel H Bridge Motor Driver Module Robot Chassis Servo Geekcreit - https://banggood.app.link/2qVY6NLoC9

    50A-Dual-Channel-H-Bridge.JPG

    I am leaning towards the Cytron, because of the many good reviews on it. However I will probably need to attach an heatsink on top of it no? If so, how do I go about this, do you use special glue (thermal paste) and just glue it on top?
    EDIT: To answer my own question, I read this from the Cytron manual: "Fully NMOS H-Bridge for better efficiency and no heat sink is required." so that's great :)

    I currently own an Arduino Uno, which according to @Thanos can only output 8-bit on the PWM pins. Did some research on this and came across a PWM extension for Arduino which allows 12-bit:
    PCA9685 16-channel 12-bit PWM - https://banggood.app.link/hWcL7gcpC9
    This would mean I could drive all motors with just 1 Arduino and with 12-bit instead of 8-bit?

    Upon doing some more digging I came across this article which makes it possible to generate a 16-bit PWM: https://www.teachmemicro.com/generate-arduino-16-bit-pwm/ (only on pin 9 and 10 as per my understanding).

    And if you own an Arduino Due, you can call: analogWriteResolution(12); (https://www.arduino.cc/reference/en/language/functions/zero-due-mkr-family/analogwriteresolution/)

    Please note: I just did some research and have no experience with any of the above whatsoever. I only did one project with Arduino before. But I figured it might be worth sharing here. :nerd

    Regarding the connection of the sensor, I wanted to mount it on the back side of the shaft. So I requested if it's possible for them to add a 8mm diameter and 20mm length extension to the shaft, so it's easy to connect it with the use of a 6.35mm and 8mm coupler. :thumbs

    custom-shaft.png
    • Like Like x 1
    Last edited: Sep 9, 2020
  9. Mike Melga

    Mike Melga Member

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    @Rens

    Hi.
    These are the hall sensors I am buying. They were recommended by someone here.

    https://uk.farnell.com/bi-technolog...sensor-hall-0-2v-20v-to-10v-180deg/dp/2319661

    The drivers I bought are these:

    https://www.robotshop.com/uk/cytron-13a-dc-motor-driver---grove-compatible.html

    Cytron MD13S

    These are the ones from the DOFReality kits.

    Did you request that shaft change?
    I didn't request anything...but probably should have :p
    What do you think?

    Just one question to satisfy my curiosity: you have an avatar picture of a Transtecno motor. Transtecno also makes very good motors and they are produced in Italy (I only knew this recently). Why haven't you choose their motors?
  10. Rens

    Rens Member

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    Hi @Mike Melga , yes I have seen those, I have purchased the same one but 360 and FS (flat surface for better connection with the coupler).

    I actually already purchase those MD13S myself (after being in contact with Cytron they recommended me that one over the other). I didn't know DOFReality uses these! They also told me to use a Shunt Regulator since I am not planning on using any batteries.

    Did you request that shaft change?
    Yes I did ask them for that change, I thought it would be easier to connect the sensor through a coupler that way :)

    The avatar is indeed from a Transtecno motor, and I did look it up but couldn't really find much. That picture is from a YouTube video from someone that either had a H3 or H6 from DOFReality. I think those are the motors they used in the early days? (I don't know).

    Below you can find a list of all items that I have purchase so far:

    Motors:
    - 80ZYT165-2420-30RV25-63B14+customized shaft

    Motor driver:
    - https://www.cytron.io/p-13amp-6v-30v-dc-motor-driver

    Shunt regulator:
    - https://www.cytron.io/p-26.4v-2.8ohm-15w-shunt-regulator

    Sensor:
    - https://www.digikey.com/product-detail/en/tt-electronics-bi/6127V1A360L-5FS/987-1393-ND/2620662

    Couplers:
    - https://www.123-3d.nl/123-3D-Flexibele-motor-koppeling-6-35-mm-8-mm-i2471-t3045.html

    Cabling:
    - https://droneshop.nl/krimpkous-assortiment-kit-150-stuks
    - https://droneshop.nl/10-awg-siliconen-kabel
    I purchase 10 awg to 20 awg, so that I have enough cables in stock. I bought only 1 meter for all, just for testing things, after I know exactly how I am going to wire things I will probably have to purchase some more wire, and perhaps some connectors, not sure yet.

    The above are things I require to start testing with code and such, since I am not using SMC3 or any other ready to go code, and will try to write my own. I have been researching other codes and will have to see how they did it and learn from it. I still have difficulty understanding the PID (code wise). What code are you planning on using?
    • Like Like x 1
  11. Rens

    Rens Member

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    ps. I haven't decided on PSU yet... I have been in contact with 2 parties regarding this. I rather spend some good money to get a good PSU with good protection than a cheap one. Cost wise I am at 1024 EUR right now. My goal was to stay below 1500 EUR, which seems to be playing out well. Just have to build the frame out of wood and purchase levers or create them myself and some gas struts and push rods and nuts and bolts :p
  12. Mike Melga

    Mike Melga Member

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    @Rens

    It's good to have someone building the same hardware based project. That way we can share ideas :)

    I did not know of that shunt regulator. Will I need only just one or one for each motor?

    You sensors look nice. I have read in here somewhere that the 360º sensors were tougher to configure. Don't know if that's true. Those do seem easier to fit due to the flat surface.

    The PSU's I am buying are these:

    Meanwell LRS-350-24

    https://www.meanwell.com/productPdf.aspx?i=459

    Meanwell is one of the best PSU manufactures.

    I will also be using this:

    https://www.ebay.co.uk/itm/1-channel-24v-relay-module-board-shield-for-arduino-with-optocoupleryu/392847826326?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

    connected to a mushroom-type button as an emergency stop button if things begin to shake out of control :)


    As for software...I will stick to SMC3. I do not have the knowledge or skill to look further.
    You have to understand that I am building my first rig. I have zero previous knowledge of these kind of motors, software, hardware...
    I set myself a goal to build one with 2DOF and traction loss and build my own direct drive wheel.
    The last time I played with a wheel was like in 1999 when I played Sierra's Grand Prix Legends. It was a Thrustmaster wheel with a 15-pin gameport connection :)

    So...everything is new to me :D
  13. Rens

    Rens Member

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    This is my first project to, figured I just go for 6dof instantly and see where it goes from there.
    I also have no experience in any of all of this. Just been researching a lot and learn as I go.

    I don't think it matters what sensor it is as long as it has the range that your lever needs to make.
    I think it's easier to have 360 so you have more margin, but I will configure min/max of potentiometer in my code. I already have some code in place, and have tried with a custom H-bridge, but really have to wait till my MD13S arrives along with the hall sensors so I can really start playing with the code and do testing/debugging.

    Where do you put that relay in your circuit? Is 10A relay enough? I am not an expert in electricity really...
    I thought I needed 6 relays, each for 1 motor so I can cut the power to the motor driver.

    I also want to use a single PSU for 6 motors, to keep things compact/clean. (not sure if this is possible either).

    I don't even have any wheel, pedals, shifter etc. yet. Just the VR headset really :)

    I did not know of that shunt regulator. Will I need only just one or one for each motor?
    Yes I believe so, I ordered 6, 1 for each motor. You can see circuit below. The "Optional additional protection" (fuse/diode) is not required btw.


    Shunt Regulator Connection.png
  14. Mike Melga

    Mike Melga Member

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    @Rens

    I really don't know if 10A is enough. I again copied the function of the DOF Reality systems:



    (minute 13:45)
  15. Rens

    Rens Member

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    Ok, I guess you will just have to try it out, if you see fire or smell something you will know ;):p
  16. Mike Melga

    Mike Melga Member

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    Attached Files:

  17. Rens

    Rens Member

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  18. Gadget999

    Gadget999 Well-Known Member

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    My Motion Simulator:
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    I use three of these motor drivers 100A and have not missed a beat !

    https://images.app.goo.gl/a8ifyw1HdsSZGXYaA


    Some arduino compatible boards have 13 bit resolution that over 8 thousand steps !
  19. Gadget999

    Gadget999 Well-Known Member

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    Iirc simtools can only output 255 steps of resolution !

    So a high resolution board may be wasted
    • Disagree Disagree x 1
  20. SeatTime

    SeatTime Well-Known Member

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    I'm currently using a 'Output Bit Range' of 16bit from Simtools.
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