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Gyro goes crazy

Posted by Marc Puig on September 12, 2011 at 5:52am

After some crashes, the X-Y gyro started to give wrong values, I've made this video:

https://www.youtube.com/watch?v=kVbhHbRXSS4 (the blue line represents the X gyro). 

 

Apparently I can't see any physic damage. I've noticed that if I put my finger over the gyro chip it reacts giving high values. Maybe I broke it with the electrostatic charge of my hands...

 

Another problem I have is the analog readings of the battery, they are not accurate (~0.3V of error). I found the source of the problem: I measured the voltage the ArduPilotMega transmits to the IMU and it's only 4.65V so all analog readings are referenced from 0 to 4.65V instead of 0 to 5V (I power the board with an external battery, not usb cable). Without the IMU shield the ArduPilotMega gives the same voltage. The voltage of the external battery is 5.01V.

 

Firmware tested: latest ArduPilot and ArduCopter versions downloaded from mission planner.

Sorry for my bad English :(

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Tags: analog, battery, crash, gyro
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Replies

  • Marc Puig September 28, 2011 at 12:53am

    This is the response I got from diydrones store support:

    This does appear to be a hardware problem, and is most likely due to the gyros not contacting well with the PCB. We have found that this may sometimes happen after the boards are soldered, from wear during use, or when the boards are damaged such as during a crash. Our warranty covers factory defects identified during the 30 day warranty period which is stipulated in our terms of use, so unfortunately your board is no longer covered by the warranty. If you would like to try and fix the board yourself, you or an experienced friend can try to fix the board by re-flowing the X-Y gyro at 325 degrees Fahrenheit. This may help if the gyro is no longer contacting well with the board.

    I've re-flowed the gyro and now the IMU shield works well! I hope this may help more users.

    Diydrones store support is great, they answered extremely fast. Thanks!

  • Marc Puig September 14, 2011 at 3:00pm

    Today I've received a new APM, the gyro is ok but I have the same problem with the analog readings... :( I'm using another arduino as an OSD, I think I'll use it to measure the analog values, but I prefer to measure them on the APM and send them through serial port to the OSD.

    Can anyone measure the VCC of the board? (for example: the VCC in the telemetry port) Thanks!

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