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
Thankyou for taking a look at the problem. I am very new to apm so i am still learning. I was under the impression that when mission planner had a 3d lock and that my hdop was below 2.0 i was good to go. Is there a way to verify in realtime that my ekf is good ?
LifeSTyle,
If you have Tower connected it should tell you but also when arming, try arming in Loiter, It won't let you arm unless it has a good lock and position estimate.
LifeSTyle,
Thanks for the report.
Ok, so what happened here is takeoff happened before the EKF was confident in it's position (i.e. before home was set). The EKF actually never became confident enough of it's position so the home was never set and the autonomous modes were never enabled.
Generally we don't recommend taking off without a GPS lock if you hope to use GPS flight modes. Bad things happen like the RTL location (aka home) is set wherever the vehicle happens to be when the EKF does finally decide it's position is ok.
Anyway, it should be possible for the EKF to become happy while it's flying but it's not something we've tested too much on the dev team so we can look into that further.
Hi.
I tried to use RC8 on the same copter that crash with RC7. After a few minutes of flight received a message in MP - Error compass variance, after that copter tilted approximately for 30 degrees and started to fly in opposite direction. Fortunately I landed it without crash.
2015-07-27 18-37-04.bin
As I can see I have acceptable level of vibration for IMU and not acceptable for IMU2. I think is it a root of problem. Is AC3.3 more use IMU2 data that AC3.2?
Evgency,
Yes, you're right. Thanks for the self diagnosis. We can see that the vibration levels are quite often in the 50m/s/s range (i.e. 5G) with peaks up to 80ms/s/s (8G). That's perhaps 4x those of my IRIS. There's also clipping happening and it starts at the moment the EKF Check goes off.
This data is quite helpful in that it gives us an upper bound where we know problems start happening.
I don't understand how it happens, that two accels placed on the same board have such different vibrations.
Evgeny,
We can't explain why one shows more clipping than the other I'm afraid but it could be some kind of physical effect of board flexing maybe.
This log is making us re-think whether the solution we put in place after your previous crash did any good. That solution was to de-weight the accels that are clipping but in this case things started going wrong even before they began clipping.
What's unusual about the vibration it is in the horizontal direction. Normally the vibrations are in the vertical direction presumably caused by the motors and propellers but in this case, it's in the horizontal direction which makes us wonder if something is bumping against the flight controller.
Some questions:
1. you don't remember which direction the vehicle leaned in do you? We have two attitude solutions running and they disagree so it's hard for us to be sure which one to believe. You helping us break the tie would be good.
2. Is this a 3DR pixhawk or another manufacturer's board? We don't mind the source of course but it removes some variables if we know.
3. how is the flight controller mounted? Can you provide a picture?
4. if you have a log of this copter flying AC3.2.1 that'd be cool.
Thanks for support. Answers:
1. Lean to left side, you can see MP log in attach (fly from 70% of length of log)
2. It is Pixhack. It have anti-vibration plate inside with sensors.
3. It is on double-sided adhesive tape and attached by buckle (see photo below).
4. I try to fly today or tomorrow.
P.S. You write: "That solution was to de-weight the accels that are clipping but in this case things started going wrong even before they began clipping."
I not very good speak English (as you can see), can you explain what mean "clipping" in this case? It is mean sharp?
IMG_20150730_120721.jpg
2015-07-27 18-28-58.tlog
Evgeny, Jesus, Paul, Artem,
Well, I wouldn't have expected that! I've heard of the PixHack but did not know it had built in anti-vibration isolated IMU. It seems like a good idea but in this case at least it's performance is not good. I'd recommend going back to the more traditional 3M vibration dampening foam.
Evgeny, we don't actually have a lot of vehicles with this level of vibration. I was wondering if you could leave it in it's current configuration and test -rc9 when it's out in about a week (or maybe a little less)? We're going to try one more idea to improve vibration resistance. After that testing is done, I'd recommend using the 3M foam or something similar.
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