The APM dev team is delighted to announce the release of APM:Plane 2.74, a major new release with a lot of new features. This release is recommended for anyone flying fixed wing aircraft with an APM2 or PX4.
There are a lot of changes in this release, but some of the highlights are:
- new APM_Control attitude controllers.
- new TECS speed/height controller from Paul Riseborough.
- two new flight modes, ACRO and CRUISE
- new camera trigger by distance system, for better aerial mapping
- dozens of small fixes and improvements from two months of development
- lots more documentation, including tuning guides for all the new parameters
Scroll down for a more complete list of changes, but before that I'd like to give you a bit more detail on the highlights above.
New Attitude Controllers
The new "APM_Control" attitude controllers have been in development for a long time. Originally developed by Jon Challinger last year, they were extended by Paul Riseborough and made compatible with the existing parameter names. The key advantage of these new controllers is their improved handling of noise, and much better ability to tune for your aircraft. There is a new tuning guide in the wiki which gives detailed instructions on how to make the most of the new capabilities.
One of the big effects you will see with the new attitude controllers is better handling of pitch compensation in turns. The new PTCH2SRV_RLL parameter makes tuning for flat turns much easier, which has been a major source of frustration in the past.
The new controllers also handle sensor noise much better, especially if you use any D term in your roll or pitch controllers.
New Speed/Height Controller
The new TECS speed/height controller is the second major controller change in this release, and will make a world of difference for aircraft with an airspeed sensor. After a lot of testing I decided to make TECS the default in this release, although you can switch back to the old controllers using the ALT_CTRL_ALG parameter if need be. If for some reason you find you do need these old controllers then please let me know, as I am planning on removing the old controllers in the next release.
The previous airspeed controller for speed/height suffered from a major problem that it gave absolute priority to airspeed. If the aircraft could not achieve the target airspeed you had set then it would dive to gain speed, even to the point of diving into the ground. This made it quite fragile, and you had to be very sure of your airspeed configuration.
The new controller operates over a range of airspeed values, set using the ARSPD_FBW_MIN and ARSPD_FBW_MAX parameters. That controller will try to meet both the airspeed and altitude demands of the mission, but if it can't reach the target speed it will happily fly a bit slower, as long as it doesn't get below ARSPD_FBW_MIN. You can control the relative priorities of speed versus height using the TECS_SPDWEIGHT parameter. See the full tuning guide for details.
New ACRO flight mode
After a suggestion from Thomas in the 2.73 release thread, we have added a new ACRO flight mode.
This modes brings rate controlled stabilization to APM:Plane, and should help give you an "on rails" manual flight experience. It is a lot of fun to fly, but it is not for beginners!
We're planning on expanding the ACRO mode in future releases. Right now it is great for "locked in" flying, and also good for loops and handles inverted flight very nicely. It doesn't yet handle knife-edge or prop-hanging.
New CRUISE flight mode
After a suggestion from Hein, we now have a new CRUISE flight mode. This mode is ideal for longer distance flying without a pre-programmed mission. It is like FBWB, but also does ground track heading hold, with heading update via aileron or rudder.
I've been testing CRUISE at my local flying field, and it is the easiest mode to fly in APM. Just steer the plane around the sky, and when you stop steering it locks onto a ground track and holds it. It isn't a good mode for takeoff and landing, but once you are in the air it is great.
New camera trigger system
When using APM for aerial mapping where you want photos taken at regular distances, the previous system was to setup a grid mission with a "camera trigger" mission item at regular intervals within the mission. That worked, but led to overly large and complex missions. You can now just set a single parameter CAM_TRIGG_DIST to the number of meters of flight between photos, and the APM will take care of when to trigger the camera. This makes for much simpler missions, and also works in other flight modes, including FBWB and CRUISE.
Lots of smaller changes
As is usual with a new release after a couple of months of development there were a lot of smaller improvements based on feedback from users. Many thanks to everyone who gave feedback and contributed patches!
Here is a partial list of the changes:
- added new GND_ALT_OFFSET parameter for ground station barometric correction
- made it possible to set the failsafe battery voltage and battery level at runtime via parameters
- added MIXING_GAIN parameter for controlling the elevon and v-tail mixers
- fixed stick mixing range in AUTO modes (thanks Soren!)
- fixed mode logging in dataflash
- added support for the EagleTree I2C airspeed sensor on PX4
- added new RCMAP_* parameters for re-mapping control channels (good for DSM and SBUS receivers on PX4)
- made it possible to configure board orientation at runtime, to make setup easier without rebooting
- switched to new task scheduler for more accurate internal timing
- added a new RELAY_PIN parameter for setting up camera trigger via a digital pin
- added secondary rudder support, useful for when a separate servo is used for a nosewheel and the rudder, or for v-tail planes with nosewheels
- fixed RTL glide slope when starting above the target RTL altitude. Descent should now be smooth over long distances. Many thanks to Kitsen13 for raising this.
- fixed a bug with FBWB airspeed control. Many thanks to Gabor for reporting this
- Added FS_LONG_TIMEOUT and FS_SHORT_TIMEOUT parameters. Many thanks for the suggestion by Aleck
- fixed handling of deadzone parameters on RC channels. Many thanks to Soren for reporting this
- many small C++ fixes from NeuroCopter. This sort of detailed review of our code is much appreciated!
- fixed analog in handling with some unusual devices - thanks to Andi for noticing this!
- added support for apparent versus true airspeed calculations based on pressure altitude, for better flight control at higher altitudes
- avoid writing unchanged bytes to EEPROM, for faster updates and less wear on the chip
- cope better with large yaw changes in the AHRS code
- improved the reliability of USB connections on PX4
- added PX4 support for RELAY (thanks to Marco Bauer)
- fixed handling of high spin rates in AHRS (thanks Jurgen!)
- removed support for the old APM1 1280 based boards.
This new release has a lot of new features that should improve the flying experience for all APM users. The APM dev teams wishes all APM users many enjoyable flights, and we hope you have as much fun flying this release as we had making it.
Happy flying!
Replies
@Pravit
Regarding your HIL problems...this sounds very similar to the issue I noted much earlier in this forum (see page 2). For me, every firmware after 2.68 has had this same problem where the MP HUD starts to deviate from FG and eventually the plane becomes uncontrollable. It happens after a few minutes of straight-level flight, but turns will exacerbate the issue rapidly. I'm using windows, most recent MP, FG (tried diferent versions, but normally I use 2.0), and the Rascal model. Tridge mentioned that he would try to take a look at this, but I haven't heard back yet...
Has anyone else seen this or have any ideas what settings we may have wrong? Thanks.
Can someone explain how KFF_THR2PTCH works?
Would it help me to not to pitch down when i set higher speed in cruise?
Thx,
Gábor
I can see in ArduPlane.pde, update_GPS that the check if the plane is moving has been removed. So has the call to ground_start.
The variable ground_start_avg is still there and is being written to but never read from.
Is everything under control here? How do I convince myself that init_home will not get called if eg. the APM resets on a brownout in flight?
Regards
Soren
I am wondering which parameters TECS will use if there is no airspeed sensor installed.
I find TECS difficult to tune, it keeps stalling the plane in tight turns due to lack of throttle usage.
Hello
I use FlightGear and HIL fw 2.74b to simulate my flight plans. I found something weird. When airplane get to the waypoint that will has the hard turn (90 degree or more) the airplane will pitch up by the HUD on MP shows it pitches down. So the APM corrects this by adding more pitch and reduce the throttle and cause airplane to stall. It is quite often the airplane stall in this way. I believe I saw this weird since fw 2.73 but not quite sure. I has tested this with Cessna172, Rascal and Malilo and they are happened in the same way.
Hello,
Thanks to the great work of the developers, my test bed, EZ Star I, was flying to WPs like it was on rails. The FBWA was working very nicely as well.
I do have one question though. On FBWA, I get a very slight turn to the left. I mean really slight. My Manual is pure straight and level. Is there a way to tune out the FBWA subtle turn?
Thanks,
Steven
On page 14, I reported a problem with the AHI after leveling the APM. This was after updating to MP ver. 1.2.61. I reloaded 1.2.60 and problem solved. I am reporting in a new post for easier identity for those of you who may be scratching your heads. In other words, I believe it to be a bug in 1.2.61.
Hello.
Please tell me, should I reset the settings on the APM 2.5 hardware after upgrading the firmware from the APM Plane 2.74beta2 to 2.74b? Heard about crashing the airplanes because of the same reason in RTL mode but don't know on what firmware version it was happened.
Sorry If I am asking the questions which is already asked, but I wont to know for sure.
Hi Guys,
Installed 2.74 on a previously flashed APM 2.5 and it completely fixed my altitude hold problems. Altitude on my F2 was typically within 5 feet and airspeed within 5 MPH. Great job!
Has anyone tried the camera triggers yet?
Jimmy
Hello all,
I just advanced the rev of my MP to 1.2.61. I have 2.74b FW installed. After a successful tuning flight, I was going tweak a little more.(you know that irresistible urge we all have to fix something until it is broke) While I was at it, I decided to re-level the plane. Much to my surprise, no matter how I tried, the leveling process kept putting in an automatic down pitch. I would say about 8-10 degrees. Before I declare the APM broken, I go in the house where I keep an exact "stunt double" of the APM in the plane. And yep, the same thing is happening? Any ideas? I am posting this in the MP thread too.
1. Have any of you seen this?
2. If so, what is the fix?
Thanks,
Steven
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