Developer

Arducopter 2.1.1 alpha

This is a work in progress. I've tried to address some fine tuning and performance issues.

Denny R. had made a comment about the inertia of bigger props causing issues. I've added a low pass filter to smooth the positive acceleration of the props to see if we can get at this issue. It may require tuning up Rate_P for a few folks, but I saw little issue in multiple flights.

Crosstrack had a small math error that decreased the resolution of it. I've fixed that and upped the default gains to get better tracking. 

Made WP hit radius 1 by default. even 3m is too much for quads. (If you pass a WP you will move on to the next)

The Loiter method is tuned a little better by default, and now uses GPS offsets when flying less than 1.5m/s. Code experimentation will continue on this front. Thanks to Emile and afernan for their help!

A fix in the Z Accel startup was added to get an averaged result.

Added the ability to enter Loiter with Optflow enabled. - still a work in progress, not for everyday use just yet.

This alpha is on GIT now and is for user's who want to test code. As always, you need to use the "relaxpatch" version of Arduino you can find in the downloads section. 

Update: We've found and patched some small type bugs in the latest and updated some GPS drivers in the Library. Be sure to pull the latest code and check http://apm.tridgell.net/ for the status of each build run against the SIL sim server.

Update r3:

I pushed a version on to GIT that addresses a number of issues.

- the low speed GPS XY calculations were incorrect and have been fixed

- Nav_Rate I term has been removed in loiter control - it's too easy to get two iterms working out of phase

- A second derivative has been added to Roll and Pitch. I found it removed wobbles nicely - Can be adjusted in the planner as STAB_D with a default of .25 (just enough)

- Smoothing has been applied to the motor commands in a way that really quiets down the alt hold pulsing without much effect on latency

- Yaw now has a dynamic constraint and I've upped the yaw gain.

- The motors output now have an LP filter on them so that the accelerate just a tad slower than the deceleration. This is a test to see if it helps big Octo's and Hexa's

- The Rate_I term is now zero'd for first five seconds after takeoff to keep balance.

- Loiter gains are lightened up a bit

- Nav_Rate_P is lower to remove back and forth sped related hunting in loiter

- Compass is enabled by default

- New I2C Library now included which should solve I2C related lockouts

- optflow is still a work in progress.

Update R4:

This update is based on flights today in a very windy environment.

It occurred to me that we're handling the WP nav I terms incorrectly and I reworked the WP navigation to share the same I terms from the Loiter. Even though they use different error input, etc, they turn out to both deal with wind in the same way. I have not Flown WPs with this new code, but heavily tested it in the sim and It's really rocking in hard wind. Transitions from Loiter flight and Nav flight are very smooth. Please let me know if you have luck.

Update R5:

This is a quick patch based on a bad crash Marco had. My theory was an I term that built up during wind that needed to be reset, but wasn't. It's a corner case but It bit Marco pretty bad. Please re-pull if you have R4 running to go to R5. And please, please be careful. This is alpha code not for general testing, but for development. Don't fly it on anything you would feel bad about crashing. 

Jason

Update R6:

Includes fix for Acro mode reset bug.
I went through all of the global variables and gave them lengthy descriptions. It's worth a read if you want to learn more how the internals work. I'll be doing some more organization like this as we move forward with an architectural redesign for 3.0 \
This version is mostly clean-up, but does include 1 interesting performance enhancement. It's disabled by default because It's fairly untested. The idea is that the wind compensation created by the Iterms for lat and lon in Loiter and Navigation are carried over into Stabilize. This unifies all of the modes so that when you switch modes, you don't get a small, but fast change in pitch or roll. This is only noticeable in high wind environment. 
To get this to work, I look for near zero velocity and start moving the pitch and roll into the wind control items. This takes a  transformation from copter frame to world frame, but the result is the copter will hold the position against the wind with the sticks in the center of the controller. If you fly around the wind compensation will bleed off slowly - about 30 seconds.
Again, this is off by default and needs significant testing, preferably in the HIL sim first.JNL has already started and flown this version for real.
The feature may be off by default for another version or two, but just letting you know it's there.
I think it will go a long way to making the mode changes feel seamless.

Update R7:

Added an auto-land timer for RTL. If you don't change modes for 20s after the copter arrives at home, it will begin to auto-land. If you have failsafe and no GPS, you will immediately begin auto-landing.
Failsafe RTL now goes 10M up as it RTLs to avoid obstructions.
Added SIL test for failsafe. 

Update R8:

Minor tweaks and cleanup

Update R9:

Made climb rate controller for landing universal for all altitude changes

Update R10:

Updated Loiter controller - Works great in the sim, thanks Afernan.

Thanks,

Jason

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Replies to This Discussion

Permalink Reply by afernan on January 5, 2012 at 3:58pm
Apart of the nominal settings, i see crazy behaviours due to incompatilities with other programs that interfer in the sim, like for example Camtasia screen recording, and maybe others. Once closed, the sim works fine.
Permalink Reply by Guy Gauthier on January 6, 2012 at 4:57am

Angel: I will take in consideration, softwares and process running in background.

Thanks!

Guy


DeveloperPermalink Reply by Marco Robustini on January 6, 2012 at 5:02am

Firrt record the fly with the internal recorder of AeroSim, then close the planner, start to grab the screen of the sim and play the recorder fly.

Permalink Reply by Don Brooks on January 5, 2012 at 6:41pm

So I know the feature is brand brand new, as is HIL with x-plane, but I've been running 2.1.1 r6 on there. The disarming of the motors on land is a nice feature, but I think I've missed something. The motors are disarming at about 2-3 meters in the air. Does this somehow look for 0 movement in X, Y and Z axis for a specific length of time before shutting down the motors gradually, or does it just kill them as soon as the land command is assumed to be executed?

My pre-land waypoint is at 3m, with a 5 second delay to allow any movement to be dampened. Land is at 0 altitude.


DeveloperPermalink Reply by Marco Robustini on January 6, 2012 at 2:36am

The Auto Land function is under progress.
I hope Jason put a parameter for enable/disable the automatic land if RTL is engage, with some heavy setup like mine the automatic land is not a nice idea.
They must also be included on several securities with the automatic shutdown of the engines, because in case of failure of some sensors may turn off the engines in flight at high altitude.
I think the best way is to put a new flight mode manageable with the radio switch, called "LAND" or "RTL+LAND", selectable by the planner.
In the tests we are making on the simulator in many cases do not turn off the engines, the drone continues to slam on the ground indefinitely, and the altimeter is much precise with the sim.

Permalink Reply by afernan on January 6, 2012 at 5:55am

Real flight test on 2.1.1. r6

I´ve long tested in my two copters (small and medium size). No wind. Started with defaults.

I´ve concentrated in LOITER, since the rest of modes works pretty well.

I can summarize the following.

- There is always a "swing" or "bounce" around LOITER point that I can´t eliminate. It remains between 3-6 m . Sometimes gets smaller, but again start the movement.
- Increasing the LOITER_P, increase the size and speed of the swing. Default value is the best.
- LOITER_I increase the size of the  movement but become slower. It must be kept low (<0.1 - 0.05)
- STAB_B increase doesn´t show a clear improvement (up to 0.4). Back again to deffault (0.2)
- Reducing LOITER _P = 0.15 and LOITER_I=0.2 eliminate the swing, but LOITER point is not precise (moves in an area of 10m)

In summary, I miss an effitient damper control component, that let us increase P and I without diverge.

Comparison with HIL behaviour.
HIL is almost perfect, but real flighht not. What can we deduce?

HIL copter and GPS signal are "perfect" versus real hardware.

We can say that (IMHO):
1.- the code is correct
2.- The code is not robust enough under imperfections of the hardware (yet).

...see next chapter

Angel


DeveloperPermalink Reply by R_Lefebvre on January 6, 2012 at 8:11am

Yes, it could be true that the code is not robust under imperfect conditions.  But maybe your hardware has a particular problem?  Maybe bad vibes that are making the gyros really struggle?

Permalink Reply by afernan on January 6, 2012 at 10:32am

Robert:

I´ve been using this same hardware (2 quads and 1 Hexa) since many months ago without a single crash (afortunally, LOL) and tested most of  fw versions till then.

I know that it works very well in loiter for other fw´s (I can name you some examples like the 2.0.49, my mod 2.1.0 AF#2 and even ardupirates).

So, I´m trying been as honest as possible while reporting my tests, changing one thing at a time, in this case only the fw. I´d like that this code gets fully perfect.

So, yes: IMHO, I´m pretty sure my hardware is good enough to flight test and give reliable conclussions.

The r6 code is safe enough to be tested by someone with a minimum of experience, in my opinion.

Best

Angel


DeveloperPermalink Reply by Jean-Louis Naudin on January 6, 2012 at 10:40am

Today, I have done some REAL tests flights of the ArduCopter v2.1.1 R6 in hard wind conditions (very gusty) with my quadcopter and I can say that its OK for me. The stabilization and the Loiter performances are really improved Vs the previous versions.

Regards,

Jean-Louis


DeveloperPermalink Reply by R_Lefebvre on January 6, 2012 at 11:32am

Angel, I'm just trying to figure out how come some people (like Jean-Louis) have good luck with some, but not others.

Permalink Reply by Chopper on January 6, 2012 at 2:59pm

What missing is the D  (PID) which is the dumper we all miss.

This is exactly my problem as well.

As i write before the hardware can do it!!  i did it with the ardupirate (PID controlller) with the same APM. so its possible and its defiantly software problem.


DeveloperPermalink Reply by R_Lefebvre on January 6, 2012 at 3:25pm

But then why do some have good results with the way it is now?  That's what I'm trying to figure out.  Either it's something in the code affecting the setup that we need to understand what it is.  Or some setups aren't being done right.

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