Hardware sensor filters - to use them or not?

Posted by Tomas Soedergren on October 12, 2011 at 3:23pm

I am currently putting together my first Arducopter hexa and as I am going through the manual wikis I am slowly realizing that everything might not be fully updated to reflect status of current hardware and firmware.

Reading the instruction it seemed like a good idea to activate the Oilpans hardware sensor filters, by solding the three bridges.

http://code.google.com/p/arducopter/wiki/AC2Assembly

But after doing so the attitude update seems to be very SLOOW. Not just smooth - SLOW.

Tilting the board 15 degrees and it takes around 9 seconds for the Flight Data attitude indicator to fully reflect the attitude change. Thats slow!

Is it good/ still recommended / normal?

Are you guys using the hardware filters or not?

And by the way, what are they? Just a R/C lowpass filter?

Comments please...

Thanks / Tomas

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Replies

  • ThomasB November 23, 2011 at 12:16am

    Hi Tomas

     

    The Low Pass Filter which is enabled by soldering has a border frequency around 2 kHz.

    Without this filter higher frequencies will be sampled too, which will have negative effect to the sampled data result.

    APM samples the gyro data with a much lower frequence, so it's not the question of 'should the filter be activated'. The question is: should we set down the low pass filter frequency  ;)

    Back to your question. After the activation of the Low Pass Filter you should not feel slower response, if yes, there must be an other reason.

     

    best 

     

        Thomas

     

  • Rz_Ten1 November 23, 2011 at 12:06am

    I don't know if this is your problem, but I've been dealing with the slow gyro updates for about a week now and I've finally figured out what was causing my issue.  I always connected the battery monitor cable before the main battery power cable, and when I do this about 75% of the time the gyros start doing the super slow update thing.  If I connect main power first and then the voltage monitor it works every time.

    This assumes you're using the onboard battery monitor function, of course.  :)

  • Developer
    Jani Hirvinen October 12, 2011 at 7:12pm

    As default those filters are enabled and they should be.

    Have you reseted all your settings? And what type of motors/hardware you are using?

  • steve October 12, 2011 at 5:12pm

    I always saw that when I don't make sure the copter is completely still during initialization.

  • Moderator
    Michael Pursifull October 12, 2011 at 3:30pm

    Also, since you are relying on the Mission Planner as your input, I recommend a simple test to eliminate a possible unrelated issue that might be misleading you.

     

    Using Mission Planner, go to Configuration->Planner. Find the checkbox for "Use GDI+" and select it.

    Restart Mission Planner, and connect to your APM. Does it respond normally/faster when you move the APM?

    If not, undue the setting. If it does, then the issue might not be related to the filters at all.

     

    It is an easy test, so I hope you will indulge me.

     

  • 3D Robotics
    Chris Anderson October 12, 2011 at 3:25pm

    The manual is correct and reflects latest firmware/hardware. Are you sure you didn't make an error in the soldering and short something out?

     

    Feel free to unsolder those pads if need be. It shouldn't make a huge difference one way or another. 

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