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My 3DOF project is born!

Discussion in 'DIY Motion Simulator Projects' started by AldoZ, Mar 20, 2011.

  1. AldoZ

    AldoZ Member

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    Hello dudes.
    After the great help of this forum, eaorobbie, frakk and the other guys, now I can to show to you my newborn 3DOF project :)

    I am in full test time but unfortunately my third Jrk12v12 is broken so I have to stop main experiments for the time I need to buy and to have another one jrk12v12 :( .

    first to see that one of the Jrk was broken, I could do various experiments about how many amps my motor draws and especially many tests about mechanical limits of the three platform legs in the various type of movements and inclinations.

    I am very sad about my broken jrk because without this forced stop now I made ​​my first experiments with the rFactor running under the X-Sim :resent:

    Sure the joy about my creation is very high but believe me, to be almost to the top and not be able to reach it is a very bad feeling.

    If you want to understand the Jrk problem you can go to this link (pololu forum):
    forum.pololu.com/viewtopic.php?f=15&t=3735

    Now I am forced to do just the tests about left and right leg with my stern leg in stop condition. Better than nothing.

    Here the pics:
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  2. Ads Master

    Ads Master

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  3. Frakk

    Frakk Active Member

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    Good job Aldo! I would try to make the moving upper part much lower for stability and safety.

    Have you tried if the motors will be strong enough for vertical movement?
  4. eaorobbie

    eaorobbie Well-Known Member Staff Member SimTools Developer Gold Contributor

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    My Motion Simulator:
    2DOF, DC motor, JRK, SimforceGT, 6DOF
    wow looking good but agree with Frakk on height of top platform reducing this will take some forces of the motors,
    power for vertical lift cant see a problem mate tested my units on me joyrider with 200kg in chair for extreme weight test and not slowing in motor movement or excess heat. Units can dead lift 150kg easy, so when ya times the power by 3 plus spring backup cant see an issue.
    Jrk problems the only issues i've had is burning out the inbuilt power regulator because of hooking in too much amps, unit still works but needs a usb connection at all times or the max and min values wander, still go as a demo unit but.
    If ya havent got any burn marks on the card or strange electrical smells it all should be still go. Something to try would be a firmware re flash which ya can download from pololu v1.3 a strong power spike or too much amps can cause the firmware to corrupt sometimes.

    Again looking good, didnt hear from ya for awhile, so I thought ya shelved it, but I was wrong looking good.
  5. kubing

    kubing Member

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    nice implementation. good effort bro.
  6. AldoZ

    AldoZ Member

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    Thank you all dudes! your help and support it's great! :cheers:
    Today I am very happy 'cause I find the jrk problem! not broken, just my weldyngs was not perfect!.
    Now new weldings done and the Jrk working great!

    @Frakk :
    About height, yes, it's a bit too tall.. just I had made the project mantaining the original dimension of the spring (a car damper). Sure I will to follow your words and I will cut about 30/40 cm the total height.
    ehh Frakk I remember when I wrote the first post on this forum.. you just start to help me since now (and it's really good for me to show to you my progress!) and without your initiation and help in this forum I could not absolutely be at this level. :clap:

    @eaorobbie :
    mate in first I need to say to you that your idea of using winches was great! (an idea that allow to start to think about making a 3DOF!!) and a big thank you for all! :cheers:

    I am very curious about the amps draws when the motors are at full cycle.
    When I try to move my motor (changing continuosly the motor direction) at full cycle (without wheight to be lifted) I get my motor draws 7/9 amps.
    Maybe It's not the best thing in the word but is better than nothing.
    I think that when the platform will lift the weight of the final configuration so the total amps will be over the 12 of the Jrk specifications..... lucky the jrk12v12 can handle peaks of 30amps but this matter remain to be seen until I run the new tests (tomorrow!).

    About my third Jrk lucky it's working! just my weldings was really ugly! :blush:
    Please teach me about your problem of the the inbuilt power regulator burned.
    how many amps were handling? And what do you mean when you say that after the accident you need to use the usb connection at all the time? I have already my jrks all the time connected via usb!! :?

    @kubing:
    Thank you!! :)
  7. eaorobbie

    eaorobbie Well-Known Member Staff Member SimTools Developer Gold Contributor

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    My Motion Simulator:
    2DOF, DC motor, JRK, SimforceGT, 6DOF
    to start with i had my jrks hooked to a mastro rc controller, biting too much off attempting a 6dof first up, quickly changed to 2dof first off, then discovered that i could talk to the jrks directly took a while to work out because the pololu crowd just kept saying read the manual.
    We live on a property so power is not too clean got a 45amp surage through the first power supply i used, modifed pc psu, not good, heard the pop saw the smoke,but by the time i hit the power button too late, hence now running 20amp fuses between power supply and jrks, and a decent filtered power supply, no worries now all safe as houses. Only used the usb on the jrks to set the mins and max then unplugged them from the usb and let the maestro go to work.

    Still hoping to use the rc card to build a servo controlled dash as xsim talks to the maestro with ease and hold 12 servos so that a dashboard with 12 guages cheaper that any bought unit but a little involved in setting up.

    And mate the help that goes around here is getting better just with there was more people like Frakk and kubing would make it alot more frendlier for new guys just coming in, there a bloody lot to get ya head around, motion sim building is not easy, but once ya got the basics it the ideas begin the flow, so thanks to all i wouldnt have a sim without their help and pats on the back.
  8. AldoZ

    AldoZ Member

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    @eaorobbie:

    ahh very unlucky mate and I am thinking too about the use of some fuses to avoid bad amps peaks. This motor controller is great but I don't want to risk to broke it.. Italian distribuitors is empty of Jrk12v12 and order from USA can mean over a month to have another jrk...

    Here my video of today, first decent tests about mechenical stress (plus an always good jorge baker song :happy: ):
    (The video is edited without the anoyng pause times)

    test done using the JRK configuration utility
    1/2 of motor duty cycle
    1/6 of motor accelleration
    (really far from the maximum obtainable performance! )

    http://www.youtube.com/watch?v=t7qCj_qZoUc

    PS:
    at 1:15 sec you can listen the CRACK sound... just I need to add some another iron strips to join better the 2 parts of my wood dais (the forces start to be high!)

    PS2: at the finish you can notice the drift of my platform.. this is cause I exceeded the maximum height of the spring with the motor arm.


    Soon my vids with X-Sim! ;D
  9. Frakk

    Frakk Active Member

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    It is great to see that my help doesn't go wasted guys. :)
  10. kubing

    kubing Member

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    too bad if you gonna wait for a month..maybe somebody around here have some. :yes:
  11. AldoZ

    AldoZ Member

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    Hi guys, some news here:

    In first, for the first time I tried to use X-SIM (3 axis) using test palet with very good results!
    I tried to use test slider 21 to move left and right legs cloned and inverted (when I push up the slider so left leg go up and the right leg go down) plus stern leg moved using slider 22.
    All very good and with a good speed (perhaps closer to flight simulators that racing sims).

    The real first problem is that my JRK can't obtain the maximum available motor power! :eek:
    With my tests using max duty cycle and max acceleration I obtain that the single motor can lift more or less 70/75kg slowing down slightly. If I try to lift over so my motor get slowing much and my JRK get overheats (I get maximum currect exceeded from JRK config utility many times).
    So I wanted to take my doubt off (it's the motor or the jrk limitation?) and I try to use the motor directly connected to the battery to try to lift up 100 kg and I obtain that the motor lift up 100kg easly without slowing!. Then the problem is from the Jrk.
    Just the Jrk can not give enough current to the motor for lift up weight over 70kg. (jrk limitations are 12amps continuosly with 30amps peaks)

    I want to says to you that in the final configuration sure my platform no plans to put 70kg directly in the vertical of my motor leg as these tests eh! :) But I would more!

    It's not the end of the world.
    I have again 210/225 kg (the 3 legs summed) available to be lifted with my platform (I figured my final configuration with an human onboard + all racing or flight devices will be more or less 130/140 kg) but maybe I find a way to obtain the 100% motor power using the Jrk.

    Sure, I can raise the max amps from 12amps to an higher value from the jrk config utility but sure I risk to burn my Jrk.. so today I will to try to using some relay to obtain my motor get the amps from these relay instead from the Jrk!.. The jrk will provide just a very little amps value to the relay, just to excite these. So later, will be the relay to provide the amps to the motor.. theoretically I can get 100% of my motor power.
    My english is not enough good to describe correctly this process but today I will try this solution and later I will can says to you if I had a good result.

    :hi:
  12. eaorobbie

    eaorobbie Well-Known Member Staff Member SimTools Developer Gold Contributor

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    My Motion Simulator:
    2DOF, DC motor, JRK, SimforceGT, 6DOF
    With my setup , i stuck a small heatsink onto the md03a chip (big chip)plus installed a small 12v pc fan on top,
    no problems with heat then. I run at 100% everything if much slower than 80% movement starts to lag a little.
    And yes the movement will be more suitable for flight with a litle experimenting with lever lengths and pivot locations you should be able to get a good car movement, plus relying on battries not good ya must keep them at full charge or ya might only get about an 1 hours use in total and with age the voltage can rapidly drop.
    And another point the higher the platform is the more (N) force is required, so i would place the actuator levers all the way down ,hence the position of lowest vertical movement then setting the base as low as possible to the motors lets say 1 to 2 away(25-50mm). Plus the lever on the winch should not be much larger the gear that it is mounted too. The gear itself is about 125mm in dia so the lever for optmion torge and speed should only stick out 25-50mm from the gear itself resulting in 150mm to 175mm of movement, which is ample i feel.
    Anyway my two bits.
  13. Frakk

    Frakk Active Member

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    There are a lot of variables in the overall power delivery. 1) Power supply has to provide enough current and keep voltage, 2) Motor driver has to deliver this current without overheating. 3) The motor has to be matched to the supply voltage and current not to draw too much, or too little. Don't expect too much from the jrk12v12, it is a low power driver and has to be cooled as much as possible. Higher the temperature, less power is delivered.

    I don't know how you plan to use relay's with the pololu, but you're wasting your time and risking damage to the circuit.
  14. AldoZ

    AldoZ Member

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    Ok dudes, I made my power tests and result is : AMAZING.

    I'll try to explain with my bad english the main logic to obtain winch motor at 100% of his power without heating the Jrk!! yeah you understand, the jrk12v12 remain as fresh as it was in the Alps and the winch motor connected going at 100% power! :thbup:

    1) JRK motor outputs no longer connected to the motor but connected to 2 relays (the same inside the winch!)

    2) Relays connected to the motor

    3) the VIN and GND connected in the relays and in battery too

    4) when the Jrk receiving the input from pc :
    the Jrk give to the relay just the amps to excite it
    5) the relay give maximum amps power to the motor (25amps)

    6) the motor will go to maximum performance (duty cycle 600 - accelleration 600)

    7) now my jrk can control the winch motor at full power and my Jrk remain fresh and relaxed (no heatskin or fan needed)!!

    8) I try to put 100+ kg perfectly above my leg motor and the winch motor has raised the weight without any effort!! the jrk providing amps very under the jrk limits (limit is 12amps).
    Yesterday when my test was without the relays so with a weight of 70 kg I had the motor slowing down and struggling and the Jrk that is heated so much! So a very BIG step forward!

    9) the switch motor direction from software (jrk utility or X-SIM) remain perfectly working.

    10) The negative point:
    With the use of the relays I can't set my Jrk duty cycle or accelleration. I will have always the max power of the motor 600 duty cyle and 600 accelleration.
    A bit inconvenient when you need to do some tests in relax because the motor is always in full power mode. For some tests is better to have the motor running slow (example for to watch how the rods are working or when you try to find the end zone of the leg movement)
    So for someone maybe is not the best way to use the motors but if you want all the power using the poor and weak Jrk12v12 now you can! :uups:


    Tomorrow I will cut the height of my spring following your words about safety, performance and mechanical stability and tomorrow I will change the wood dais in another one more resistant

    ps. Today for a distraction my arm motor (the iron piece mounted in the gear) has really destroy the dais under it......
    at least I realized even more the enormous power of these engines but unfortunately with this accident I broke a potentiometer.. ;P

    Please tell me what do you think about the relays method!
  15. Frakk

    Frakk Active Member

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    First, it would be nice to know what kind of relay is used, and how you wired them up.
    Having only max speed is not only inconvenient, but it also turns a simulator into a cheap arcade ride. The movements will be unrealistic and very rough.
  16. eaorobbie

    eaorobbie Well-Known Member Staff Member SimTools Developer Gold Contributor

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    My Motion Simulator:
    2DOF, DC motor, JRK, SimforceGT, 6DOF
    agreed wrong way around it. my jrks run for over 6hrs some nights with all sorts of heafty guys tring to wrangle the best time of the night yes jrks reach a temp of 45c but functions without no problems. got me stuffed with what ya doing.the movement at full speed only defeats the purpose of using the jrk, ya should go bigtalltims way, the k8055 with relays.
    Plus ya might find ya height and angles on the main connecting rods are wrong, its easy design a system but to get all the kenitics right and have the unit moving the mininum weight possible is the key to a low cost system.
    or just buy the already made mega servo from pololu $278 last time i looked,
    its a jrk with 12v motor on reduction box (winch/wiper) lifting 100 odd pounds with no effort or heatsink. So bets me. Over and out
  17. kubing

    kubing Member

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    :thbup:
  18. AldoZ

    AldoZ Member

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    Yes Frakk, you are right. Your words are similar to the doubt that I had.
    I have not done tests with x-sim with all this power but I do not want the movement becomes too violent. Just I don't want to overcome the right mix between a realistic movement and pure power.

    if I wanted to have less power using the relay (So no problems about heating and 12amps jrk limits too), I would just use relays that provide less amps.
    With 25amps relays = 100% power (at maximum effort winch motor draw 25amps)
    with 20amps relays = 90% power (more or less)
    ecc

    BUT AFTER ALL THAT I have a very big question, one thing that I have not yet understood:

    when X-Sim give the input to the Jrk so this input has always the same motor force?

    Example (without use of relays):
    I set my jrk using the config utility in this mode:
    duty cycle = 500 of 600
    accelleration = 300 of 600
    ok, now I start an rFactor session.
    I play the game and I decide to make the first track corner very softly and slowly with my car so I get my motor arm move in a certain mode (should be!).

    Now I play again and I decide to make the first track corner very hard and with fast car.
    So Now I should get a faster motion right?

    Or maybe between a slow and a fast corner I can obtain just a different platform inclination?

    In other words, can the X-SIM input to the Jrk provides a speed movement attribute?
    Or just when I make a fast corner in rFactor I can just and only obtain a more platform inclination??

    Today after the work I put the electrical schema about relays configuration
    • Optimistic Optimistic x 1
  19. Frakk

    Frakk Active Member

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    X-Sim outputs a position. The jrk goes to this position based on the PID settings and maximum acceleration/speed values. The PID should be tuned so the physical position (feedback) follows as close as possible the X-Sim position (setpoint).

    How the cars feel on each track will depend on the profile. Given same car, same track and same profile, a larger G-Force will generate a larger movement (tilt angle). If you turn suddenly, G-Force changes suddenly, and the chair should move very quick too until it reaches the G-Force (tilt angle / position) too.
  20. EL-CORAZON

    EL-CORAZON New Member

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    USING 20AMP RELAY INSTEAD OF 25AMP WOULD NOT MEAN THAT THE RELAY ONLY DELIVER 20AMP..U WILL HAVE THE SAME BRUTAL FORCE GOING TO THE MOTOR... WITH BOTH.
  21. AldoZ

    AldoZ Member

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    @EL-CORAZON:
    Yes you are perfectly right. I was wrong when I wrote of different amps relay to choice the power percentage and when I wrote that is the Jrk that to excite the relay.
    The relay is connected directly to the battery so the motor will take directly the max amps from battery. Just a 25Amps relay will broke if it handle over the 25amps. A 30amps relay will broke if it handle over the 30amps ecc

    @Frakk:
    Thank you frakk, now I have no more doubts about the input that the jrk12v12 receive from X-SIM. Just the position based on the PID.

    @eaorobbie:
    Mate, now I am trying to find the better legs and spring position so that the engines make less effort possible.
    For now I decide to use my system without the use of relay.
    when I did some tests with a person sitting on the platform, I'll know better what my engines strive.
    I hope that all my calculations about force/effort/legs and spring positions are correct to obtain my platform working without the relay trick.
    I would to have the possibility to configure how I want the duty and accelleration of my motors!


    Today I cut my spring, and tomorrow I will cut my platform legs for the new spring height. Tomorrow I will to try to remount all too.

    Soon I will show to you all the new configuration pics :)

    Ps. Thank you ALL!