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Author Topic: Runaway robot  (Read 451 times)

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Offline obiwanjacobiTopic starter

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Runaway robot
« on: May 17, 2013, 06:52:29 AM »
Hi,
[not sure if its a hardware or software problem]

I have build a kit for a car robot and am using the Arduino Uno as its brains.
On the work bench it works fine, but when I go out into the real work it looks like the program is going crazy.

Is there a common cause that makes your MCU go nuts?


PS: If you need more info, please say so. I will give all details that are needed.

Offline johnwarfin

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Re: Runaway robot
« Reply #1 on: May 17, 2013, 10:53:31 AM »
ive also experienced that with some early builds. in one case it was sunlight interfering wih optical encoders and switching to hall effect fixed that. a couple other runaways were due to motor noise reseting the mcu. a 100uh inductor between motors/battery and mcu with couple caps on the mcu side fixed that. this is not counting the many software bugs resulting in lost models.

Offline obiwanjacobiTopic starter

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Re: Runaway robot
« Reply #2 on: May 17, 2013, 03:49:54 PM »
I did some measurements on the current and voltage of my battery powering the Arduino (and motor controller and sensors). The 9V battery I plug into the Arduino power (barel) jack was just too low. I used some old rechargeable that clearly is past its lifetime. All the electronics is drawing about 100mA, so that is not too bad. I will (field) test tomorrow.  I have a separate battery pack (5x1.2V AA) powering the wheels (6V). Under load it drops to about 5.8V.

Is having a separate battery pack for the motors enough to reduce noise (only grounds are connected)?
« Last Edit: May 17, 2013, 03:55:10 PM by obiwanjacobi »

Offline johnwarfin

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Re: Runaway robot
« Reply #3 on: May 20, 2013, 05:13:27 PM »
separate power is the best way to isolate noise. personally i dont like duplicate components and like to keep cost down so prefer the rc or lc filter method. but that would certainly be a good diagnostic step.

 


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