Flight tests with ArduPilot in EasyGlider Pro

I posted an earlier blog with pictures on how I placed the avionics in an EasyGlider Pro for autonomous flight. I found out that was the easy part! Now I’m performing flight tests to hone in on the code mods for stable flight ( as Jordi states, the latest code is optimized for the EasyStar). My method has been:
Fly and observe performance in autonomous mode – record observations – make code modifications on laptop – remove GPS and upload code – replace GPS – fly again. Laborious but also fun since physical computing yields immediate effects that you get to see.
I’ve attached a table I made in Excel to organize my iterations and keep me on track. Maybe this will help others in the same situation. One mistake I made was getting in a hurry to go fly. I could have found out about the reversed servo throws and IR sensor placement by just walking the plane around on the ground and changing its attitude by hand. This would have avoided the “death spirals” I experienced on that first day of flying!

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3D Robotics
Comment by Chris Anderson on May 9, 2009 at 6:43pm
Glad to hear it. You weren't flying the latest 2.1 code before? (We haven't updated the code for a few weeks, so it hasn't changed recently). Can you post your Easy Glider PID settings? I'll try it next week.
Comment by Bryan Cuervo on May 9, 2009 at 7:27pm
The code changes in yellow are the only changes made to the latest code (I have no idea of how often the 2..1 code is updated). I'm guessing the problems I had with pitch were caused by messing with the define_alt_error_max. The biggest problem I have is my lack of knowledge on control systems and programming but I’m eating that elephant one bite at a time!

3D Robotics
Comment by Chris Anderson on May 9, 2009 at 7:45pm
Nice one! Kudos to you for sticking with the tuning process on a new airframe. We'll be following in your footsteps!
Comment by Bryan Cuervo on May 10, 2009 at 3:23pm
I was suspicious of the altitude settings in the configtool. The last flight tests included an increase from 50m to 75m to 100m. Just plotted my last flight that had all altitude values set in the configuration tool to 100m. Looks like she's stuck at about 50m no matter what value is entered.

3D Robotics
Comment by Chris Anderson on May 10, 2009 at 5:36pm
Byran: Interesting. We'll check it out (we always fly at 50m anyway, so we may not have tried other altitudes)

3D Robotics
Comment by Chris Anderson on May 10, 2009 at 5:59pm
Jordi explains (we set it to a fixed altitude for the Sparkfun competition and uploaded that code. You can fix it as follows):

"Yes is correct. Is set to it 75 meters by default for sparkfun competition... ;-)

Please, go to the "Amain: tab and inside the navigation function is this piece of code:

int temp_error =altitude_error(70, Get_Relative_Altitude());

Change it to:

int temp_error =altitude_error(wp_current_alt, Get_Relative_Altitude());

And the autopilot will try to maintain the altitude set in the utility...
Comment by Bryan Cuervo on May 11, 2009 at 5:12am
Thanks Chris,
I'll make the changes and see what happens. To hold the data logger and extra GPS, I made more room in the EasyGlider. Removed the rudder servo and cut/ground into the right wall. The thin wall was reinforced with fiberglass. I'll post pictures when I get a chance.
Comment by Bryan Cuervo on May 11, 2009 at 9:31am
I went into the code and didn't find
int temp_error =altitude_error(70, Get_Relative_Altitude()); but I did find a similar line and made the following changes:

Comment by Bryan Cuervo on May 14, 2009 at 9:47am
I can't get consistent results but at least I learned you can get the plane flying level with the trim function in the configtool. Still need to figure out why IR sensors aren't working with the ailerons.
Before launching, I'll flip to RTL or WP mode and pitch the plane up and down. The IR sensors immediately make the elevator respond. If I roll the plane back and forth, there is little or no corrective aileron response.

3D Robotics
Comment by Chris Anderson on May 14, 2009 at 10:12am
Bryan: just checking a few things:

--On the 2.0.1 code, did you get aileron response, either to your hand or in the air?
--I presume you've checked all your sensors with the sensor test app
--On the ground are you seeing any aileron response when you roll the plane to one side or the other? You should be seeing something, although it's not linear and very much depends on proximity to other IR sources like your body.


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