Copter-3.3 beta testing

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!

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        • That would indicate that your aircraft is under powered. 

          • 700 = WAY under powered

            • My problem was apparently a matter of jacked-up settings. I tend to tweak my Iris's parameters a lot. When a new firmware release comes out, I typically merge new relevant-looking settings with my current parameter file, keeping my settings, and go with it. It usually works out pretty well. Sometimes the effects are pretty cool. (Try merging Iris+ WPNAV_* settings with a WPNAV_SPEED of 1350 to see what I mean.)

              Anyway, I'm guessing the 700 THR_MID came from the "classic" Iris days when the Iris was kind of a dog compared to how it performs now, and I didn't merge it for whatever reason. I can't remember, but it's always been the setting I've used. 

              Several authoritative sources here are saying 700 indicates a grossly under-powered machine. But my Iris is basically a bone-stock Iris+ with no extra crap attached, which seems strange. It certainly doesn't act under-powered to my eye. So I played with it some more this evening. 

              At 300, 65% throttle is required for a hover. Switching to AltHold causes it to start rising in altitude, which makes sense obviously.

              700 requires 45% throttle, and switching between Stabilize and AltHold requires throttle adjustment. Aside from the "drop" issue (which I'll get to later), this is the way I've gotten used to flying when switching modes. I just compensate without thinking about it. 

              A setting of 500 for THR_MID maintains a stable hover at exactly half-way up on the throttle. Switching to AltHold maintains the same altitude, with *no* change. (It's almost as if these settings are correct!) So, 500 it is. 

              As for the "drop" issue: It would only happen the first time I switched to AltHold from Stabilize after arming. The copter would drop until I moved the throttle *at all*, at which point it would hover according to the current throttle setting. After setting THR_MID to 500, I didn't notice it, so it may be something in 3.3 that reacts differently to a dumb THR_MID setting than 3.2 does.

              Also, I found the parameter I need to adjust to fix the "vertical acceleration" problem I was having. It's PILOT_ACCEL_Z. Set to a higher value (e.g. 500), it responds throttle inputs in alt-compensated modes more the way I like for it to. ACCEL_Z_P/I (apparently new names for THR_ACCEL_Z_P/I) seem to control how fast it can rise and fall in general. With the high settings I specified (when I thought they were the relevant settings), the copter (in Stabilize) can climb at crazy high speeds. So I put those back to their stock settings.

          • Well, it's an Iris+ (actually original Iris upgraded to "+" configuration). No weak motors, bricks strapped to it, etc. So what would make it under powered? A couple of nights ago, I was flying with a 10mph tailwind in a field along a highway with a 60 mph speed limit. A couple of times, I started at the east end of field and "raced" cars going past on the highway, while flying over the field. In a couple of cases, I passed them. Suppose they were going 50 mph instead of 60. Still, that's 50+ in an Iris. Doesn't seem under-powered to me, but maybe I'm mistaken. 

            • 70% throttle to maintain a steady hover is incredibly underpowered.  Something's clearly wrong. If you're confident that there's nothing wrong with the 'copter, have you tried a different LIPO?

            • The fact that it drops when going from Stabilize to an altitude controlled mode would indicate that THR_MID is set too high. That is, in Stabilize hover you probably have less than 50% throttle applied from your radio transmitter. When you switch to Altitude Hold or Loiter, the flight controller sees less than 50% throttle so it figures it has to descend.

              All this doesn't explain why this wasn't the case with previous firmware versions but I think this is probably what's happening. If you look at the logs, what does "Throttle Out say when you're in Stabilize hover? Whatever that read should be the setting for THR_MID.

              Edit::: Actually, I had missed where you said it only happens once, so there probably is something else going on?

    • hmm, it does not happen to me. it sometimes drops down from alt hold into stabilize if you did not have throttle leveled up to where it needs to be, but I just flew in both alt hold, loter, stabilize - did not drop down once.

  • I'm still flying 3.2 and after careful set up and calibration have zero error messages and it flies flawlessly. Perhaps if others simply want to fly without testing might want to just use 3.2 for now. 

  • Developer

    I would like to remind everyone that this is just a release candidate, not a full release. This is where we ask the wider community to give us feedback so we can address problems and bugs before we do a release.

    So if you are flying a release candidate then you should not expect perfection. You should also not base your decision to return hardware based on release candidate warnings.

    The Ekf is relatively new and we are still polishing it. Too many people are getting too many warnings for my liking and we don't have clear solutions to these warnings.

    Please be patient as the devs are under a lot of pressure at the moment.

    I would also like to apologise for the slow reply to some of you. I have been away for work and have not had time to reply as I am limited to my phone. I will be back on line in another 5 hours or so.


    • Leonard, I totally understand what you are saying here. I am very grateful, as we all are for the efforts of all the devs on this project - you provide an awesome service to all us enthusiasts, and we wouldn't be able to practise our hobby/profession(in some cases) without the awesome efforts you selflessly provide. I also appreciate the situation with beta code - I just raised the post here purely to ascertain if my issue was down to my own hardware setup or if it was something code related. As regards returning hardware - I wasn't considering doing this because of the EKF issues, but for the IMU2 Vcc filtering issue which is purely hardware related (just bought a second HK copy based on pixhawk and this also has the Vcc issue causing bad accel/mag health reports unless I first short the power cables before connecting battery).

      Can I ask though - in order to take 3.3 and switch off EKF, returning it to the filtering methods of 3.2.1 - is it simply a case of setting EKF_CHECK_THRESH to zero? 

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