VSI is jumping

Hi my VSI gage is jumping aroung with the quad just sitting on the ground....am i missing something here? here is a vid..... and i have the latest FW on it.. Oh i do have a sonar on it but its the ez4...could this be it?

VSI.3gp

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  • It is interesting to read this post after recently getting my new APM2 and starting bench testing over the weekend.  I first noticed the VSI jumping around on my APM1 after updating the software around the 2.0.49 level.  This is going back a while so I apologise for not being specific.  Eventually I ignored the VSI jumping around putting it down to the baro and older APM1.  However I am not sure now.  

    With my new APM2 on the bench and no sign of any vibration source  I see the APM2 VSI readings jumping around.  This leads me to believe the VSI issue has remained and is inherent in the APM design or the baro unit is no better than the one in the old APM1.  It has been a concern of mine since the APM2 was released it has serious internal noise issues. In addition many have commented the APM2 is so sensitive it has to been encased in very thick foam (1-2 inches) otherwise it will not work. In other words you cannot secure it to the frame on thicker double side tape or a simple rubber pad

    For now I am not planning on installing the APM2 in my multicopters until I am convinced it is reliable and the sensor issues are resolved.  People have reported crashing due to unexpected reboots, magnetic compass reversal, MPU6000 ranging issues and the list goes on.   Looking at the rapidly changing VSI readings one has to imagine the software is already fighting to compensate for this even before the copter is flying. The same could be said for the noisy APM2 electronics and this might just explain why very little progress has been made in achieving stable alt hold or loiter.  For example, with the latest loiter testing on 2.6 people are still reporting their multicopters wandering around and not able to hold a fixed position.

    Don't get me wrong the software developers do a hell of a job, but I think the electronics issues in the APM2 are letting them down, constantly having to cancel out the noise / sensitivity effects.   I will spend more time now looking at the APM2.  I am quite happy flying my quadcopter on 2.0.54 with APM1 which is nice and stable and does not suffer from the problems of the later releases and new hardware.

    Hopefully some attention might be given to the VSI now there are more people seeing this in the APM2 not just APM1.  It is particularly significant  seeing this on bench testing with no other external factors acting on the APM other than minor temperature fluctuations.

    I should point out we expect to see some variability on the baro readings, but given it is a VSI reading its probably not coming from one sensor.

  • VSI is the vertical spped indicator

     

    Have you got a bit of foam over the baro sensor? it could be wind buffeting the sensor. but i dont think the baro comes into play untill higher altitudes.

     

    I'm having problems with noise on my sonar and looking at the logs it is the source of the VSI problem. where ever there is a spike on the sonar signal there is a corresponding + and - on the VSI. its basically reading 1m then going straight up to 2m then straight back to 1m, so there is a fast jump up giving a big postitive vertical speed then a fast drop giving a big negitive vertical speed.

  • Same here, VSI gauge is jumping around.   Not sure if it has always been like this.  APM1

  • I have the problem of the baro reading jumping around on the ground also.  I think mine jumps around a little more than 20cm.  Looking at the VSI guage in the latest MP, it constantly bounces from 2 to -2 or more.

  • I have same trouble But not big like you.Copter is on ground and VSI (baro) meter bouncing up and down around 20cm also in raw data from baro sensor.

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