1. Do not share user accounts! Any account that is shared by another person will be blocked and closed. This means: we will close not only the account that is shared, but also the main account of the user who uses another person's account. We have the ability to detect account sharing, so please do not try to cheat the system. This action will take place on 04/18/2023. Read all forum rules.
    Dismiss Notice
  2. For downloading SimTools plugins you need a Download Package. Get it with virtual coins that you receive for forum activity or Buy Download Package - We have a zero Spam tolerance so read our forum rules first.

    Buy Now a Download Plan!
  3. Do not try to cheat our system and do not post an unnecessary amount of useless posts only to earn credits here. We have a zero spam tolerance policy and this will cause a ban of your user account. Otherwise we wish you a pleasant stay here! Read the forum rules
  4. We have a few rules which you need to read and accept before posting anything here! Following these rules will keep the forum clean and your stay pleasant. Do not follow these rules can lead to permanent exclusion from this website: Read the forum rules.
    Are you a company? Read our company rules

Pololu Jrk 12v12

Discussion in 'SimTools compatible interfaces' started by Frakk, Sep 29, 2010.

  1. BartS

    BartS Member

    Joined:
    Oct 10, 2010
    Messages:
    156
    Balance:
    417Coins
    Ratings:
    +5 / 1 / -0
    1 sec = 1000ms milliseconds
    1 sec = 1000000us microseconds
    To corrects BSFT post
  2. kubing

    kubing Member

    Joined:
    Sep 27, 2010
    Messages:
    259
    Occupation:
    teacher, Industrial electronic programmer
    Location:
    kelantan Malaysia
    Balance:
    350Coins
    Ratings:
    +0 / 0 / -0
    from my experiment about 1 and half yr ago with my controller, 1ms is necessary for high kP setting to make it smooth. 10ms pause with kp = 25 can cause the motor to oscillate :thbd: .
  3. bsft

    bsft

    Balance:
    Coins
    Ratings:
    +0 / 0 / -0

    Not that it make too much difference if you are using cheap motors but if you have good motors with no slack, you sure can get better detailed motion curve...

    Oh really ! Lets see you put some motors larger than wipers on yours. THEN you can advise.
  4. bsft

    bsft

    Balance:
    Coins
    Ratings:
    +0 / 0 / -0
    OK,thanks for that, google is lying to me.
  5. bsft

    bsft

    Balance:
    Coins
    Ratings:
    +0 / 0 / -0
    Thats where PID comes into play to smooth oscillation.
  6. BartS

    BartS Member

    Joined:
    Oct 10, 2010
    Messages:
    156
    Balance:
    417Coins
    Ratings:
    +5 / 1 / -0
    http://www.google.co.uk/search?q=mi...s=org.mozilla:en-GB:official&client=firefox-a
    http://www.google.co.uk/search?q=mi...s=org.mozilla:en-GB:official&client=firefox-a
    I dont think google is lieing to you, its easy to get milliseconds and microseconds confused, abreviated both you would think to be ms however microseconds is represented by a µs to be accurate.
  7. BartS

    BartS Member

    Joined:
    Oct 10, 2010
    Messages:
    156
    Balance:
    417Coins
    Ratings:
    +5 / 1 / -0
    Your motor osscilation is coming down to the resolution of the input, the resolution needs to be tuned to the magnets in the motor and the speed you read the input at. Ideally a half motor rotation needs to equal 1 unit resolution on input that is if you have a 2 magnet motor which should equal exactly 2 units in resolution, if you have four magnet motor 1 full turn should be tuned to a 4 unit resolution on input. This priniple should quite easily eliminate your osscilation problem provided you can convert your input sample fast enough to compare.
    Its best to read input direct from the motor axel rather than the driven gearboxed, reading input from the driven gearbox causes unsettling problems for instance my motors are 25:1 on a 2 magnet motor 25 x 2 = 50 so I need 50 units of resolution to accurately be able to stop and hold the motor in a selected position at its magnets meating points.
    From the above you should be able to see that a comparison gearbox of 60:1 altho maybe slower would be more accurate at holding a certain accurate position.
  8. eaorobbie

    eaorobbie Well-Known Member SimTools Developer Gold Contributor

    Joined:
    May 26, 2009
    Messages:
    2,574
    Occupation:
    CAD Detailer
    Location:
    Ellenbrook, Western Australia
    Balance:
    20,390Coins
    Ratings:
    +1,683 / 23 / -2
    My Motion Simulator:
    2DOF, DC motor, JRK, SimforceGT, 6DOF
    well we dont have any issues with the jrk, quiet wrapped with the motion , so how about stop downing the unit and stop hijacking a thread that none of you guys have this unit.
  9. bsft

    bsft

    Balance:
    Coins
    Ratings:
    +0 / 0 / -0
    Thats right what Eaorobie says, the jrks work just fine. So if you dont own JRKS , then you have no place to bag them. so maybe you should buy them , use them , then comment!
  10. tronicgr

    tronicgr

    Balance:
    Coins
    Ratings:
    +0 / 0 / -0
    All right, sorry for asking then. Well I guess there is no need for something better. I should keep it myself. Its clearly wasting of time since you can't compare a fresh of the shelf commercial product with something DIY... Never mind!
  11. Roadster2

    Roadster2 Member

    Joined:
    Apr 20, 2007
    Messages:
    170
    Location:
    UK
    Balance:
    1,194Coins
    Ratings:
    +42 / 2 / -0
    I haven't invested in either one yet as I'm still contemplating which type of motion system to build. I do however appreciate having a choice and I can see from many of the postings on here that your boards, and help/advice, are very well thought of.
    So, keep up the good work .....
  12. bsft

    bsft

    Balance:
    Coins
    Ratings:
    +0 / 0 / -0
    Its not a matter of keeping it to yourself, I am just stating that I have NEVER built a tronic card, so I cannot comment on that.
    I believe the tronic card is quite good from what other builders have done.
    The JRK was a simple setup for me, and I am happy to recommend it as I have USED it.
    All I am reading here is information written by people from, as far as I know, have not used a JRK.
    Sure I may have made comments in the past to people whom were trying to build your old 1.5 amc and hbridge and the never ending issues they seem to have. However, I only suggested they buy jrks, and save themselves a headaches, or at least, get their sim going and work on the tronic later.
    If you want to start a t AMC vs JRK thread so we can compare PROPERLY, I suggest you do so.
  13. kubing

    kubing Member

    Joined:
    Sep 27, 2010
    Messages:
    259
    Occupation:
    teacher, Industrial electronic programmer
    Location:
    kelantan Malaysia
    Balance:
    350Coins
    Ratings:
    +0 / 0 / -0
    Cool guys..we are here not for fight. long story short. last years i setup my own experiment to test how fast x-sim USO can go in milliseconds when you REALLY need them. here is the screen capture of my test.

    [​IMG]

    Windows take about 2.09 millisecond to send 8 bit binary signal to controller at 19200 baud-rate. even with pause = 1 ms on USO software. That is the Windows hardware restriction/limitation for uart communication. The more bit you send the longer period it take. In other word you will never ever achieve pure 1ms hardware refresh rate unless you built your own special .dll for your hardware.
  14. bsft

    bsft

    Balance:
    Coins
    Ratings:
    +0 / 0 / -0
    Nice work there kubing, good to see an actual result.
  15. tronicgr

    tronicgr

    Balance:
    Coins
    Ratings:
    +0 / 0 / -0
    My tests shows completely different story here... In this capture I show the timing of capturing a data frame of AB<16bit_value><16bit_value>

    FTDI USB serial packet timing at 115kbps.png

    As you can see there is plenty of time for AMC to receive data, calculate and position the motors within a 1millisecond (1ms) :mug1:



    Here is the capture file that you can analyze in depth with scanalogic software (free) here: http://www.ikalogic.com/ikalogic-products/scanalogic-2/downloads/
    amc uart data capture (scanalogic).zip

    Thanos
  16. kubing

    kubing Member

    Joined:
    Sep 27, 2010
    Messages:
    259
    Occupation:
    teacher, Industrial electronic programmer
    Location:
    kelantan Malaysia
    Balance:
    350Coins
    Ratings:
    +0 / 0 / -0
    115kbps obviously faster than 19200kbps.

    the screen shot was taken more than years ago. With AMD Athlon x2 running windows vista 32bit. Long before USB implementation on hardware side. I dont know if my picotech oscilloscope give me a wrong reading but here is my 16bit timing for same baudrate
    [​IMG]

    Sirnoname suggest me to built my own .dll for my hardware due to windows limitation. But i solve my problem when i use 115kbps to 256000kbps baudrate to comunicate with USB version of my hardware. I push my hardware to calculate PID as fast as 0.2 - 0.4ms. At about 3.00a.m Sunday morning i realize at this speed the controller can run faster than SCN5 if you want. the only limitation is wiper motor itself. I learn something very important that morning. You know what? 1-5ms of delay only can be feel by your body when you have super fast controller to sense that. that why i always use 1ms pause on my hardware. :yes:

    Jrk is good board on the market available today if you want some fun. for accuracy i have no comment.
  17. tronicgr

    tronicgr

    Balance:
    Coins
    Ratings:
    +0 / 0 / -0
    Well, its not only to be able to feel it but to minimize the motor overshooting too... Better refresh rate less chance of overshooting the motor aka smooth transitions in direction changes.

    BTW here is some math to confirm my capture:

    115200 / 8 = 14400 bytes per second ----- 14400 / 1000 = 14.4 bytes per millisecond ( I use only 6bytes per ms having space for more)
    19200 / 8 = 2400 bytes per second ----- 2400 / 1000 = 2.4 bytes per millisecond (For 6bytes you need at least 3ms !!! )


    Thanos
  18. silmar

    silmar New Member

    Joined:
    Sep 2, 2014
    Messages:
    25
    Balance:
    - 78Coins
    Ratings:
    +9 / 1 / -0
    My Motion Simulator:
    2DOF, Arduino
    Hooo...this is too confuse, I need to learn more
  19. bsft

    bsft

    Balance:
    Coins
    Ratings:
    +0 / 0 / -0
    @silmar , you already own an arduino, forget about this thread.
  20. Chumet1

    Chumet1 Member

    Joined:
    May 10, 2014
    Messages:
    59
    Balance:
    - 2Coins
    Ratings:
    +16 / 1 / -0
    My Motion Simulator:
    2DOF, JRK
    I'm waiting until someone has finished.