I'm delighted to announce the release of ArduPlane 2.50 for your flying pleasure. This release has a lot of advances to some of the core ArduPlane code, and should be a big improvement for many people.
Perhaps the most important change in this release is the new DCM code that does acceleration correction based on the GPS. This improvement is based on work by Bill Premerlani which really advances the state of the art for attitude estimation on small microcontroller based autopilots. The improvement in attitude estimation is very noticable in flight, resulting in significantly more accurate control. Many thanks to Bill for his patience in working with Jon Challinger and myself to bring this improvement to ArduPlane.
Other significant improvements include:
- updates to the barometer driver to sample the pressure and temperature much more rapidly, leading to better altitude estimation
- updates to the AP_AnalogSource driver to be interrupt driven, allowing us to sample all analog sources much more rapidly. For ArduPlane this improves the airspeed sensor on the APM2 a lot.
- updates to the waypoint completion logic, to use a "finish line" algorithm. This prevents the problem of circling around a waypoint when we miss it by more than the waypoint radius. The waypoint is now considered complete when we pass a line that is perpendicular to the track, and passing through the target waypoint.
- improvements to the AP_Mount code, allowing for control of roll/pitch/yaw stabilisation via EEPROM variables that can be set over MAVLink. This allows you to setup the mount once, and it will resume operation as soon as you boot. These changes also fix a number of bugs in the AP_Mount code, so it AP_Mount hasn't worked for you, please try again. Many thanks to Greg Fletcher and Amilcar Lucus for the AP_Mount improvements.
- Lots of improvements to the ArduPlane parameter documentation. This documentation should be the first place you look when trying to understand ArduPlane configuration parameters. Many thanks to Andreas Antonopoulos for his great work on generating these wiki docs based on the source code markup.
- New LAND_PITCH_CD parameter to control the landing pitch when not under airspeed control. Thanks to Jeff Taylor for fixing this!
- New SCALING_SPEED parameter that allows you to set the base speed for scaling PIDs. Previously we assumed a standard speed of 15 m/s, which is too low for fast aircraft. By adjusting SCALING_SPEED you can have the same set of PIDs for both airspeed and non-airspeed flight control.
There is one change in this release which may require some re-tuning. We were using the wrong value for time delta when using the PID controller for navigation roll. This has been fixed by making the PID library calculate the delta time internally, but it means that existing HDG2RLL_I and HDG2RLL_D values will be incorrect. I have fixed the defaults, but if you have your own settings for these, you will need to drop HDG2RLL_I by a factor of 5, and raise HDG2RLL_D by a factor of 5 to get the same result as for the previous release.
Thanks to everyone who has contributed to this release!
For the next release the plan is to concentrate on improved stabilisation and navigation controllers, based on the great work being done by Jon Challinger.
Happy flying!
Replies
Reset Mission – when do we get it?
I see that the RST_MISSION parameter is in the documentation but not available in 2.50. I really need this option. When can we expect the next firmware update?
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Hi Andrew,
Here's a little more on the strange waypoint following behavior I'm seeing. I set up a 4-waypoint pattern, with waypoint 5 being a DO-JUMP to keep the plane flying. The pattern you see below was repeated with each pass of the pattern. The plane (in sim) actually behaved differently on each of the four legs, but consistently in this regard as noted. From waypoint 1 to 2, the plane followed an S-curve. The actual point it was flying to changed during the leg. It started off to the right (east?) and migrated to the center of the waypoint. The plane clearly followed the moving waypoint. However, from waypoint 2 to 3 the plane behaved exactly as expected with zero-degree cross track correction. The orange line pointed to the center of the waypoint and the plane flew stright to the waypoint. From waypoint 3 to 4 the plane flew a curve. The orange line started off to the right (east again?) and migrated to the center of the waypoint as the plane approached. Finally, from point 4 to 1 the plane behaved as if I had cross track correction in. It overflew the line a little, came back and then flew straight to the center of the waypoint.
If this is a navigation bug, could it be related to the magnetometer?
Finally, although the oval pattern is gone in loiter, the circle is off-center relative to the waypoint (see graphic). Did you make any code changes recently to correct the oval? I did reload the firmware and things seem to have changed a little.
Thanks,
Paul
Rudder Tuning
I am trying to tune Rudder Mix (KFF_RDDRMIX) so that there is zero sideslip during a loiter turn. What parameter do I need to look at the well me which way to adjust that parameter?
I see that all the Servo Yaw PID’s are 0. Why is that?
Can I use servo yaw P (YW2SRV_D) to have the APM to automatically make the sideslip 0 during a turn. I really need a procedure on the best way to tune the rudder. This should make the airplane fly with minimum drag when turning.
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Along with the change in waypoint following that I noted above (plane flies an arc from waypoint-to-waypoint instead of straight line when cross-track correction set to zero degrees), the plane also flies an oval instead of a circle in loiter. I'm seeing this in simulation mode, but I assume this would apply to real mode as well. Also, I'm using an earlier version of Mission Planner in which this was not happening before the firmware upgrade. Was there a change in navigation code that would lead to this flight behavior? Also, I set my loiter radius to a higher value to see if it would make it easier for the plane to fly a circle. It still flies an oval.
Thanks,
Paul
Hi,
In auto mode, after the “takeoff” command is ended (reaching the right altitude), the plane dives few meters and then start to climb heading to WP #2. How do I correct that?
Thanks
Itzik
Hi Andrew!
I'm looking forward to the next release! Especially the improved stabilization, my project will greatly benefit from that.
By the way, can I conduct an interview with you? its just a couple of questions (5-6 questions). I'll send a friend request with you along with the specifics of my questions. I'll be using it for my university project somehow similar to the Canberra UAV project since it can also carry a package.
Thanks! :D
Hello,
Sorry if this has been covered before - but i can't find the answer anywhere.
I have updated to ArduPlane v2.50 from the previous version and it said that i need to update my APM2 to the latest firmware.
I fly an Easyglider and the only parameters i have modded are to do with 'dual ailerons' and 'servo reversing'.
Once I have updated the firmware, Is it safe to reload the old parameter file?
What are the correct and safest steps in this case? (and should you always do a setup/reset and setup/erase)
Thank you
James
Hello, I just uploaded the new code. I am running a APM 1.0. My system has been working great. I noticed today that when I was checking the throttle output (ch3 out) the command is to be at motor off in RTL, Auto, FBW B modes. The throttle is correct when in other modes. I am using an airspeed sensor. Is this because the airplane is stationary? Is there some new feature to keep the prop from spinning?
Thanks.
I had a long flight with APM1 and v2.50 this morning. RTL, Loiter, FBW-A & Stabilize all worked fine as per normal except for Auto. It would not navigate to waypoints no matter what I tried, When switching (and with confirmation from telemetry) the plane would return to home and then loiter around home.
What factors would cause the waypoints and auto mode to be ignored?
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