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
Hi Julian,
Your log looks ok, good vibrations, but it might be worth dropping your ACCEL_Z_P and ACCEL_Z_I values by 50% and see how that feels.
If it doesn't fix the problem put the values back and let us know.
Sorry I couldn't be more help!!
Julian,
I'm having a hard time finding the place in the log that shows an issue. The desired altitude and actual altitude seem to be sticking pretty well together (see first graph below. maybe 20cm of movement?).
The desired and actual climb rate also look pretty good as well.
When my copter is loosing altitude, stationary or at the end of a high speed run, the altitude as displayed on the OSD is constant. If the copter's sensors think it has not lost altitude how can the log accurately reflect the true change in altitude?
The log may show 20cm though the actually change might be much more.
From my tuning experience on a Naze32, the alt hold tuning had 3 different parameters: P For baro vs accelerometer bias, I for voltage change over time and D for reaction force. You just increase the P and D to the point where the aircraft started osilating and then back then off a bit.
Are there equivalents in Arducopter?
Looks like this is a bad example log for my problem...
If I fly very slow or just stand still the copter hold the altitude pretty well, but if I fly faster it dramatically looses altitude and I have to switch to stabilize to prevent a crash.
I think this log shows the problem better (from 9min): https://drive.google.com/file/d/0B2P7_aBCn5tRN3JWaFZFUVNyam8/view?u...
Ok, so this is a "known issue" called "altitude loss after fast forward flight" in all versions of Copter including AC3.3 and is not an issue we were attempting to resolve with AC3.3. In this way it's a bit off topic but in any case, it's the barometer being upset by pressure differences caused by wind hitting the frame at different angles.
This is quite visible in the log. When the vehicle's Pitch angle (yellow, scale on right) goes to 40 (leaning back) the barometer altitude (dark blue, scale on left) climbs from 6.7m to 13.5m (a nearly 7m change). the 7m baro climb drags the inertial nav altitude up so it thinks it's climbing and so the vehicle descends to compensate.
There have been discussions on software solutions but at heart, it's a frame issue. A frame that's built with the baro effect in mind does not suffer from this effect. An IRIS for example does not suffer from this because it has somewhat balanced air holes on the top and bottom. A Solo does suffer from the problem because it's a closed top with a large hole on the bottom for the gimbal.
Randy please enlighten us!
http://diydrones.com/forum/topics/effects-of-frame-design-on-barome...
Are there already some good ones started or is going to be new ground for most of us?
Randy, if this is specific to pressure reading in AltHold, would this suggest that we shouldn't see this same issue with PosHold (due to its altitude being determined from GPS coordinates instead of pressure)? The reason I ask, is (and I know this isn't exactly on topic, but since the pressure phenomenon has been present in all versions historically) , is that I see the altitude drop (in 3.2.1) when moving forwards at speed (so at 45deg forward pitch attitude) when I am flying in AltHold mode. then upon a quick stop, the copter climbs to the initial altitude and holds there. Does this suggest that in PosHold, we are still using the barometer for altitude?
Paul,
I haven't seen your logs but what you're describing is likely a separate issue related to the pilot asking for a lean angle that the vehicle physically can't attain while also maintaining altitude. An enhancement request to prioritise altitude over lean angle is here on the to-do list.
Most vehicle's simply don't have the power to lean over at 45 degrees and maintain their altitude. I've been considering reducing the ANGLE_MAX default to 35deg or 30degrees but haven't yet.
In reality it's more like 1 to 2 meters. When descending it's slow, but when it's ascending it goes pretty hard. Sure doesn't look right. I'll shoot a little video with another log. I'm also taking up a 1300mm X8 with the same pixhack. See how that goes.
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