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Thread: Proble with Arlo with Eddie Control Board

  1. #1

    Default Proble with Arlo with Eddie Control Board

    Hi,

    I have bought a Arlo platform with a Eddie Control Board.

    The problem I am having is that I canīt get the motors to run.

    The encoders are connected to PIN 9-12. I changed the firmware code to "ENCODERS_PIN = 9"

    When I run GO 36 BC, nothing happens. If i repeat i few times I get "ERROR - Encoder error".

    If I comment the routine that handles Encoder error the motors still donīt run.

    When I try to turn the wheels by hand (when the power is off) they are completely stuck.

  2. #2

    Default Re: Proble with Arlo with Eddie Control Board

    You will need to rock the wheels back and forth with hand until they get un-stuck, then try power on again.

  3. #3

    Default Re: Proble with Arlo with Eddie Control Board

    I tried to do that but they wont turn. However, if I connect the wheels to the battery directly they turn, so it seems that this is not a mechanical error.

    I tried to load a very small motortest program, that does not work either:



    Con
    _CLKMODE = XTAL1 + PLL16X
    _CLKFREQ = 80_000_000

    Obj
    Motors : "Eddie Motor Driver"

    Pub Main

    Motors.Start
    repeat
    Motors.Left(35)
    Motors.Right(35)





    "Eddie Motor Driver" is the .spin file that comes with the Eddie firmware.

    Any suggestions?

  4. #4

    Default Re: Proble with Arlo with Eddie Control Board

    You probably can not turn the wheels because of the internal gearing. This is normal. Your motors seem fine.
    Infernal Machine

  5. #5

    Default Re: Proble with Arlo with Eddie Control Board

    If I remove the motors and measure the current it says 12 V during full run. If I connect the motors it goes down to 0 V. I have tried two different batteries, both working on other applications.

  6. #6

    Default Re: Proble with Arlo with Eddie Control Board

    Hi Hotta - Let's see if we can figure this out...
    You can not free-spin the Arlo wheels because of their internal gearing. This is normal.
    This is normal on the Arlo platform as Publison says. The motors have a worm drive in their final output gear that does not allow the wheels to "free spin" because the worm's angle of attack is very steep.

    The original Eddie motors could be rotated by hand, because they used a different gear ratio.

    If I remove the motors and measure the current it says 12 V during full run. If I connect the motors it goes down to 0 V. I have tried two different batteries, both working on other applications..
    I don't understand "...measure the current it says 12v...", it doesn't compute. Do you mean that there is current (amps) flowing or not? "Volts" is a measurement of potential, and "amps" is a measurement of "current flow".

    To measure current in the motor circuit you need to connect an amp meter into series with the current carrying wire. To measure voltage you need to connect power to the motor and then measure the voltage across the motor terminals - this should test out to be at very near battery voltage.

    So, the question would be, what is the voltage (measured across the motor terminals) when you connect the battery directly to it? And then, what is the current (aka amperage) flowing through the motor - that is measured by putting an ammeter in series with the battery and motor - essentially inserting the meter into the current flow circuitry.

    Lets' see what those numbers are and then we can know what's going on and get you up and runnin'

    -MattG
    - Matt Gilliland -
    - mattg@parallax.com
    - (916) 624-8333 x3018
    Ask me about the Lifetime Warranty on the Propeller BOE

  7. #7

    Default Re: Proble with Arlo with Eddie Control Board

    Sorry, my English is not perfect so a swapped the words current and potential.

    Scenario 1:

    12 V battery connected
    No motor connected
    Motor test program (see earlier post) running

    Measured 10V between motor output "ports".


    Scenario 2:

    12 V battery connected
    Motor connected
    Motor test program (see earlier post) running

    Measured 0V between motor output "ports".
    Motor is not turning

    Scenario 3:

    12 V battery connected directly to motors

    Measured 12V and motor i turning.


    I do not have access to the Eddie control board right now, bu I will measure the current as soon as I can and give you an update.

  8. #8

    Default Re: Proble with Arlo with Eddie Control Board

    Hoffa, Did you ever get this issue figured out?

    I've been working on getting the Eddie code to work with an Activity Board and HB-25 motor controllers. I found the motor control code kept turning itself off.

    I think this section is what was causing the issue (starts on line 556 in the "PDIteration" method).

    Code:
      ' Check to see if offset is higher than it should be for the current power level (When motor is moving)
      if ||Difference > SAFEZONE and ||Difference > ||SetPower[Side] / Kp + DEADZONE
        ' If so, bring the set point closer to the physical position
        ' MidPosition equals MotorPositionSample approaching MidPosition, as limited by SetPower / Kp + DEADZONE
        MidPosition[Side] := MotorPositionSample - (-(SetPower[Side] / Kp + DEADZONE) #> -Difference <# (SetPower[Side] / Kp + DEADZONE))
        if StillCnt[Side] => DIVISOR                       ' If the offset was high and the motor hasn't moved for the last second
          Motors.Stop
          PDRunning~                                        ' Then something is wrong -- stop the motor driver
          outa[24..19]~~
          cogstop(cogid)
    I believe the code assumes if the motors are stopped and the target distance wasn't traveled, then there's a problem with the motors not working properly so the code shuts the motors off. I believe this is a feature left over from the earlier Eddie code which used different motor controllers.

    Until a better solution is found (which I'm currently working on) I think you should just comment out the last five lines of the code listed above.

    Let us know if you're still having trouble. While my current work uses HB-25 motor controllers, I think I'm almost to the point of understanding the code well enough to help with conventional h-bridge controlled motors.

    Just to be sure, you're using these encoders right?

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