Connect with us

** Need Help Designing Automated 12v DC Motor Test Fixture

Discussion in 'Sensors and Actuators' started by jatkinson91, Jan 25, 2012.

Scroll to continue with content
  1. jatkinson91

    jatkinson91

    3
    0
    Jan 25, 2012
    I am in need of a test fixture for an automotive door lock actuator.

    I have a door lock actuator using a tiny 12v DC electric motor (Mabuchi FC-280PC-22125) -- this motor has 5.56A stall current.

    I have sourced a new electric motor and want to test it thoroughly in the actuator to make sure it doesnt also die in short order, like the OEM version does.

    To do that, I want to build a test set up which will cycle the motor until the built in limit switch indicates full lock. Then wait 2 seconds, then reverse polarity until the unlock limit switch is triggered. The lock and unlock trigger switches send current to inputs in the wire harness connecting to the actuator. So, for the purposes of this project, they will be translated into current to indicate when the actuator has locked, and when it has unlocked.

    I would love for this set up to be powered off a standard 120v AC wall outlet, but if thats too difficult a standard 12v car battery will suffice.

    I also want a counter that is keeping track of how many locks and unlocks. If that is too difficult, I guess I could just time it and assume the average cycle time is X seconds and get my total cycles from there.

    Is there such a thing readily available, or would this need to be built from scratch?

    I appreciate any and all help with this project.

    Jeff
    [email protected]
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,397
    2,777
    Jan 21, 2010
    It sounds somewhat specialised and I doubt if someone just happens to make something to do this for sale (it is possible that the manufacturers of this equipment may have something that performs a similar function in order to test their devices)
     
  3. Harald Kapp

    Harald Kapp Moderator Moderator

    10,060
    2,146
    Nov 17, 2011
    You could use, partly, the car door's electronic:
    Measure the time it takes to open the window and to close the window.
    Connect the contacts of two relays in parallel to the open and close contacts of the switch in the car's door (or dashboard or wherever it sits).
    Close the relay's contacts altarnatingly for at least as long as the time you have measured. Let the car's electronics take care of the limit switches for the actuator (it does so when you push the switch manually for too long a time).
    A simple NE555 multivibrator can do the job.
    Let the setup run for the intended time of test.
    After the preset time, stop the test setup and calculate the number of cycles by dividing the test time by the sum of open time and close time as defined by the 555.

    That's as simple as I can imagine without resorting to some logic and figital counters or presumably a microcontroller.

    Harald
     
  4. jatkinson91

    jatkinson91

    3
    0
    Jan 25, 2012
    I appreciate the replies but let me simplify this question :

    I want to take a tiny 12v dc motor and spin it 1 way for 1 second, wait 1 second, then spin it the other way for 1 sec and again wait for 1 second. Repeat 100,000 times.

    Motor stall current 5.56a

    I dont want to use the car's internal wiring to accomplish any of this because the car is $50,000, the motors have been known to burn up and short out causing fires and all sorts of electrical problems.

    For these reasons, I want to do this test on a work bench completely independent of the vehicle electronics.

    If I could buy something that I could plug into wall outlet and adjust dwell times that would be even better. Something readily available off the shelf would be ideal so Im not well versed in IC's

    Jeff
     
  5. duke37

    duke37

    5,364
    769
    Jan 9, 2011
    A circuit such as this could work. I doubt if a wall wart could be found that is powerful enough but a battery charger and capacitor or small battery would provide a supply. Alternatively, CB power supplies at about 5A are available and have a controlled voltage.

    The circuit as shown just changes over a two pole changover relay. Timing is set by the variable resistor, this should be set to give the required dwell time after the motor reaches the end stop.

    I assume that the motor reverses if the power is reversed.

    A mechanical push button counter could count cycles if wanted.
     

    Attached Files:

  6. daGenie

    daGenie

    43
    0
    Jan 23, 2012
    when is d project due?
     
    Last edited: Jan 26, 2012
  7. jatkinson91

    jatkinson91

    3
    0
    Jan 25, 2012
    I have mistakenly written above that we could just time the motor 1 sec fwd, 1sec backwards. This will not work. As the motor wears out, it will move the mechanism less and less during each 1 second interval. Eventually, it would not be reaching lock or unlock.

    Instead, I will need to use the +12v limit switch inputs within the actuator to tell the motor when to stop. It sounds like I need a microcontroller and a motor driver.

    Any suggestions?

    When is project due? ASAP. Im wanting to test a repaired actuator to validate the replacement motor.
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,397
    2,777
    Jan 21, 2010
    I would suggest an arduino, an appropriate "shield" designed to drive migh current loads, and a trip to a local hackerspace to try to find someone who can give you some hands-on help.

    If you've never programmed one of these then you're facing a very steep learning curve, even for something as simple as this.

    Making a mistake would be bad, because a power supply capable of delivering high currents can easily destroy stuff if you wire it incorrectly.
     
  9. daGenie

    daGenie

    43
    0
    Jan 23, 2012
    i designed a circuit 4 ur application, but attaching the file is proving difficult................im still trying and hope it works this nite....................
     
  10. daGenie

    daGenie

    43
    0
    Jan 23, 2012
    d files r 2 big...............if u give me ur email address, i'll be more than happy to send it to u
     
  11. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,397
    2,777
    Jan 21, 2010
    daGenie, upload them somewhere and provide a link. (imageshack perhaps)

    if they're images, make them smaller.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-