Warning #1: an issue has been found with Tower's Pause button which can cause the vehicle to fly to an old position if the vehicle has not sent a position update to Tower in some time.
Warning #2: Copter-3.3.2 fixes a bug found in Copter-3.3.1's desired climb rate initialisation which could lead to a sudden momentary drop when switching from Stabilize or Acro to AltHold, Loiter or PosHold.
Warning #3: Copter-3.3.2 fixes an issue found in Copter-3.3.1 which could lead to hard landings in RTL or AUTO if the WPNAV_SPEED_DN was set too high (i.e. >400 or 4m/s) and/or the WPNAV_ACCEL_Z was set too low (i.e. <100 or 1m/s/s).
Warning #4: a bug was found in Copter-3.3 which could cause a sudden crash if you abort a Take-off initiated from a ground station. Video description is here. The bug is fixed in Copter-3.3.1 so we recommend upgrading.
Note #1: AC3.3-rc8 corrected a long standing bug in the HDOP reporting. HDOP values will appear about 40% lower than previously but this does not actually mean the GPS position is better than before.
Note #2: if upgrading from AC3.2.1 the vehicle's accelerometer calibration needs to be done again.
Note #3: set SERIAL2_PROTOCOL to "3" and reboot the board to enable FrSky telemetry like in previous versions.
Note #4: the wiki will be updated over the next few weeks to explain how to use the new features
Copter-3.3.1 is available through the mission planner. The full list of changes vs AC3.2.1 can be see in the ReleaseNotes and below are the most recent changes since AC3.3.
Sadly this version (and all future versions) will not run on the APM2.x boards due to CPU speed, flash and RAM restrictions.
Changes from 3.3:
1) Bug fix to prevent potential crash if Follow-Me is used after an aborted takeoff
2) compiler upgraded to 4.9.3 (runs slightly faster than 4.7.2 which was used previously)
Changes from 3.3-rc11:
1) EKF recovers from pre-arm "Compass variance" failure if compasses are consistent
Changes from 3.3-rc10:
1) PreArm "Need 3D Fix" message replaced with detailed reason from EKF
Changes from 3.3-rc9
1) EKF improvements:
a) simpler optical flow takeoff check
2) Bug Fixes/Minor enhancements:
a) fix INS3_USE parameter eeprom location
b) fix SToRM32 serial protocol driver to work with recent versions
c) increase motor pwm->thrust conversion (aka MOT_THST_EXPO) to 0.65 (was 0.50)
d) Firmware version sent to GCS in AUTOPILOT_VERSION message
3) Safety:
a) pre-arm check of compass variance if arming in Loiter, PosHold, Guided
b) always check GPS before arming in Loiter (previously could be disabled if ARMING_CHECK=0)
c) sanity check locations received from GCS for follow-me, do-set-home, do-set-ROI
d) fix optical flow failsafe (was not always triggering LAND when optical flow failed)
e) failsafe RTL vs LAND decision based on hardcoded 5m from home check (previously used WPNAV_RADIUS parameter)
Thanks for your testing!
Replies
Here is a picture and you can see it up on the 3DR tower. I have used this configuration for a long time without this issue.
These are all excellent suggestions that I will be following up on and implementing, but if you look at the logs, it is just chugging along smoothly, then it instantly drops many of its satellites, so its position appears to change. These interferences could affect things, but they are pretty constant, so I'm not sure it would suddenly see a lot of interference all at once. I will know more as I go through these steps, though. Thanks for the excellent suggestions.
I want to follow up on this, in regard to my Pixhawk having abrupt changes in course when in GPS modes. Based on analysis of logs and suggestions for different configuration and some shielding, it now has much better performance. The copter now has the 1.3GHz vtx antenna on the bottom, with foil shielding on the video signal lines and covering the single-board camera. The logs now still show drops in number of sats and peaks in HDOP that look similar in shape to before, but the numbers are better, so it doesn't seem affected by them. Number of sats was high of 13 with drops to 9, now highs of 15 with drops to 13. HDOP was normally .8 with spikes up to 1.2 and now levels out to under .7 with spikes up to a max of .8. Thanks to Andy, Derek, Vesselin, Ivan, Cala, and DG for the diagnostics and excellent suggestions. My confidence is much higher with this platform now. It takes a village...
FWIW looking at your photo again, I have discovered that the cable end of LiPo batteries give off a lot of magentic interference and now mount my batteries with the cable end as far away from the compass as possible. I suspect you have enough distance for this not to matter, but FYI.
Sorry to barge in and this has probably been discusses a thousand times 'somewhere' but do you think it's advantageous to put copper foil tape on the bottom of a gps case? I have the typical black round plastic gps case on a mast. Would copper tape on the bottom be a good idea? Seems a but less messy that copper foil on all the wires. Thoughts? Thanks
copper base helps a bit. but what helps way better is to use properly filtered 5V voltage feed, from a BEC separate from the one that feeds flight controller. when i rerouted power and stopped using 5V from the COM port where GPS was connected to quality of data has improved tremendously, as well as speed of sats lock.
So I've always been suspicious of this since I'm pretty sure every GPS has a ground plane anyway. I think the EMF interference is a field rather than unidirectional, so you'll be missing some of the radiation this way. That's why I think identifying the sources and shielding them is more effective.
But Cala's experience shows that it still works pretty well!
I put cooper under gps on my last build, It's changed from 10-12 sats to 18-20 sats :O and I don't need a tall mast, only a second floor over the Pix, I connected the cooper to the pix with a ground wire.
Sweet! Glad you got it sorted.
I think this kind of story shows just how vunerable GPS's really are and just how much the FC is using it. I had no idea when I first got into this. I'm also amazed how much difference shielding makes - its so much more convient than distance!
Could try connecting to ublox ucenter and doing a cold restart, then let it run for a while (30min?). I've had that help on big deviations.
What hdop and # sats are you getting?
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20
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21
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22
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23
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24
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