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Robot Goes Crazy By Itself! Help! Very Important!

Hello, I need assistance in understanding why my robot is controlling itself. It is supposed to be controlled from a laptop keyboard and it works fine at times but at VERY IMPORTANT times it starts to go crazy like its spazzing. I was testing my teams robot in the operating room at our local hospital to see if it would work with the robotic microsurgery equipment but it kept going crazy! We are trying to use the arm to help with the irrigation that goes on during surgery. Attached below is a video of the situation but the arm gets worse at times. I figured out that one of the arms joints is most likely the cause but it would be helpful to here other peoples opinions to help solve this problem. Please respond asap, it would be much appreciated!

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Check your power source, that has been an issue in the past.


The power source seems fine. We have changed the batteries but it still continues to act like that. We are using the EZ-Bv3 board. Any ideas on how to check for a defect on the board?


@Rich , Even I faced the same problem a couple of days ago, I would like to know the issues with power supply... Is it because of supplying higher voltage or what might it be?

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I recall Technopro had similar issues and it turned out to be the power supply which was causing it.

There is a tutorial on EZ-B diagnostics under the support page.

Similar can happen if the software is attempting to move a servo to a position and the supply is not man enough, or if the servos draw too much current for the EZ-B (the limit is 5A total on the EZ-B regulator). Check the maximum current draw all servos may have if they all try moving at the same time, if it's over 5A you will need to provide an external VCC to the servos.


@martinl3, a couple things can happen with too little power. If the voltage drops below 4.8 volts a digital servo can black out and reset. When they reset they usually turn clockwise until the establish signal from microcontroller again. I believe this is why the servos suddenly do that. Use a better lithium ion battery pack or a 6 volt lead acid battery ub645 is a common battery. AA batteries cannot support digital servos as they can suddenly draw a great deal more current than a AA battery pack can provide.


Any robot I build I include a small volt meter to monitor the supply this is my favourite

User-inserted image

especially when the load is over a few amps a quick glance at meter will tell if you have a voltage drop


Martinl3, My robot did that with low voltage. I purchased a rechargable battery pack from Radio Shack.

Bravia, That looks great. Do you have a link for that? Thank You Steve S

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They are readily available in a variety of colours on ebay, I have a bunch of blue ones I got a while back that I occasionally use when setting things up.


Rich, Thank you for responding. Do you have a link where I can purchase them? I will try google, Ebay.

Thank You Steve S


Get a few different colours they look very impressive, I use red for EZ supply & blue for servo's

search for voltage meter


Bravia, Thank You, I will do that. Steve S


Okay I will try the voltage check and post my results. Thanks to everyone that is helping me with the problem. I greatly appreciate it!


I love the adjustable regulators that have the built in lcd:)


@Martin , I am just checking in. It looks we we able to offer some good suggestions. I'm trying to clear out some of the old questions. Do you mind marking the thread as answered? Thank you


Remember it is not only the voltage that is important, also the curret carrying capabilities. That is where the "hump!" comes from. Make sure your battery is strong enough with enough Amphours.

my 2 cents. ;)


OH! Make sure your not plugged into the Gnd port between D13 and D14. It can short out the board.


@martin. I watched that video again. Are you using that robot arm in a surgery room?