Discussions

iris strange flight dynamics

Posted by harry sawyer on April 20, 2016 at 8:20pm

Pretty green at this and need some help to diagnose a problem:

I'm flying an IRIS+ with a gopro session and a samsung S4 on the bottom to provide a cellular telemetry link.  

The issue i'm seeing is that as it flies a mission, it keeps pausing for a second or so and then will move on.  On the video, i see the pitch go nose down a bit as it flies to next WP at 10m/s, but it keep leveling out, pausing, and then continuing on.  It appears to be doing this between waypoints.

I downloaded the telemetry, and it is most obvious as pitch variations which goes positive every 10 seconds or so it seems.   On the mission, i had to abort and land halfway because it was not making time and was heading for a battery failsafe.

It did not do this for the whole mission, just for the beginning and middle.. I have noticed the behavior on a few flights now.. does anyone have an idea of what could cause this?

Appreciate the feedback! thanks.

Harry

2016-04-20 21-39-28 40.bin

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –
Follow

Replies

  • harry sawyer April 23, 2016 at 2:14pm

    Found this in the log using the 'auto analysis':

    Test: Compass = WARN - Moderate change in mag_field (31.74%)

    this seems to be the only warning. 

    Since the problems is evidenced by the pitch changes, i checked the ATT logs despitch vs pitch - i can see that these traces are aligned.  

    following the auto analysis warning, i do see some 'spikey' activity on the magx signal.  the magy looks good with small steps changes i assume are due to turning at each waypoint.

    i looked at vibrations, and i don't see anything abnormal according to the ranges in the mission planner flight analysis guides.  

    At this point, i want to understand the mag signal to figure out if something could be affecting that sensor.  And, would these problems cause the 'leveling' i see during flight. 

    going to review some older flight logs to see if this is normal, or something new.3702230791?profile=original

    • harry sawyer > harry sawyer June 5, 2016 at 6:55am

      For anyone noticing a simliar issue, i believe this problem is the result of altitude changes during waypoints changes.  If i don't change altitude, i don't get the pauses and delays during flight.  Therefore, i conclude that there is a tuning or programming issue to be performed.  

  • harry sawyer April 21, 2016 at 6:22am
    Charlie,

    Thanks for the reply- what are the best signals to monitor to check vibration? I will search around for this an the normal ranges. Would excessive vibration cause something to 'pause'? Forgot to mention - little to no wind at all on this mission.

    I upload the t log if anyone can help. Thanks.

    Harry
  • Charlie April 21, 2016 at 1:16am
    how are your vibrations? I was having a similar problem with an x8 on auto missions, particularly with a bit of wind when passing over tall trees or buildings. Copter would seem to hesitate and lose a metre or two of altitude before recovering and continuing the mission. Issue was only apparent in those conditions. Changed flight computer mount to blocks of HK orange foam top and bottom of the pixhawk, huge reduction in vibe, particularly z axis. This brought to light quite different performance from the imus, with imu2 seeming much noisier. Disabled it and since have carried out auto missions with very stable performance in 30mph wind, gusting 40. YMMV...

    looking forward to 3.3.4 and new ekf with separate filters for each imu :)
This reply was deleted.

Activity