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


DeveloperPermalink Reply by jasonshort on December 27, 2011 at 11:37am

I'm shooting for thursday/Friday so everyone can have it by the weekend. 

I'm away from home now and away from my quads. But tomorrow I'll be testing again.

Happy NY to you!

Jason

Permalink Reply by Chopper on December 27, 2011 at 2:10pm

Is it possible to reverse the Yaw output (APM not RC) from the MP? 

RC 4= -1 reverse only the RC not the correction.

 

Permalink Reply by afernan on December 27, 2011 at 2:40pm

I have a suspect in why to some of us the new code doest´t work at all in LOITER.

I´ve discover that using HIL with several code versions (I´ve tested from 2.0.49 to now) in all cases GPS is read correctly by the MP, taking the coordenates from the simulator (AeroSIM-RC, in this case).

In all, except in the 2.1.1. (I see in the MP "gps no fix"), so maybe this could explain that LOITER is not working since there is not GPS refference.

Could anyother check that (mainly the folks that 2.1.1 doesn´t work)?

Angel


DeveloperPermalink Reply by Marco Robustini on December 27, 2011 at 4:26pm

Tomorrow i check this here. I'm sure about this, if MP doesn't take the gps coordinates from sim it's impossible the calc and correction with loiter.
I put my gps with the backup battery at 4 Hz because with 2.1.1 does not communicates with the APM.
I think there's some stranger behavior with the 10 Hz gps on 2.1.1, but your problem is another, because in HIL i think the MK GPS is not used.


ModeratorPermalink Reply by Roberto Navoni on December 27, 2011 at 6:22pm

So We found the bug ... :) When you use the 10HZ GPS you need to change the rx buffer in fast serial.h from 128 to 256 so the gps start to work :)

We doing a test only on example now Marco try in the Arducotper 2.1.1 code.

The problem is the same with old code 2.x with new gps lib.

Best

Roberto


DeveloperPermalink Reply by Marco Robustini on December 28, 2011 at 1:16am

Yes, start to work on my system but only with the GPS_AUTO_test.pde, not with the AC code.


ModeratorPermalink Reply by John Church on March 15, 2012 at 10:32pm

Hi Roberto and Marco,

Do you have a fix for explicitly defining which GPS to use? I tried changing the rx buffer size to 256, but as Marco said, that didn't allow the specification- only auto seems to work. However, it does work while connected to USB. More ideas?

Thanks!

Permalink Reply by Balloon on December 27, 2011 at 8:43pm

In 2.1.1 , I have bug about some lagging and lock control there're hold angle pitch and roll when i will move stick about more than 30 %. Which i think have some crash or some out of control. 

I download from http://code.google.com/p/arducopter/downloads/detail?name=ArduCopte...  and GIT. 

Permalink Reply by Christopher Cooper on December 27, 2011 at 10:30pm

Just downloaded this from the downloads section and loaded it on with Arduino. When I try to access the CLI through serial monitor all i get is "Init A" scrolling over and over. What have I done wrong?


3D RoboticsPermalink Reply by Chris Anderson on December 27, 2011 at 10:53pm

Christopher: what board are you using (APM1 or APM2)? You need to add a line to the APM_Config if you're using APM2

Permalink Reply by Christopher Cooper on December 27, 2011 at 10:58pm

Chris, I'm using a APM1 board with the ATMega 2560. I'd loaded 2.0 on before with no problems.


3D RoboticsPermalink Reply by Chris Anderson on December 27, 2011 at 11:04pm

I'm not seeing any problem. Can you please re-download and try again?

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