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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Comment by Bryan Cuervo on May 2, 2009 at 7:00am
Still trying to manually tune the flights. Next flight, i'm going to start over with the unaltered code and take incremental steps. I think think I'm still making too many changes without understanding the code. The Paparazzi site has some info on tuning flights that is helpful.

Comment by Bryan Cuervo on May 3, 2009 at 5:35pm
Latest thoughts, flight and more thoughts----

3D Robotics
Comment by Chris Anderson on May 3, 2009 at 6:04pm
Thanks Bryan. Very useful as always. I think you're the first to tune ArduPilot 2.1 for ailerons, so it's definitely uncharted territory. I suprised it's proving so hard, however, since the EasyStar is now rock solid and the FunJet, which uses elevons, was pretty easy to tune in 2.0. Now that you've got the sensor in the right direction, I think you're right to start from scratch with unmodified 2.1 code and see how close that is.
Comment by Bryan Cuervo on May 3, 2009 at 6:18pm
Thanks for the feedback Chris. The main issue now is the sporadic elevator response. I didn't see this in 2.0 so I wonder if it has to do with the configuration tool? Also, I double checked and there is a quirk in the code when you reverse the servos; this causes the Tx inputs to the servos to be reversed when the GPS is removed and you are "flying by wire".
Comment by Bryan Cuervo on May 9, 2009 at 12:00pm
More flight testing with 2.1. Roll behaving as expected but plane always dives when switching to RTL.

3D Robotics
Comment by Chris Anderson on May 9, 2009 at 2:16pm
Bryan, when you're testing the plane on the ground, do the control surfaces respond to tilting the plane the way you would expect? In my EasyStar setup, with the XY cable facing forward, I have to reverse my elevator servo:

#define REVERSE_X_SENSOR 0 //1 = cable behind, 0 = cable front

#define REVERSE_ROLL 0 //To reverse servo roll
#define REVERSE_PITCH 1 //To reverse servo pitch
Comment by Bryan Cuervo on May 9, 2009 at 3:14pm
When I walk the plane around while in RTL, the ailerons guide me back to "home" and the elevator rises (positive pitch). I tried reversing the pitch to see what would happened and the plane pitched up violently.
If the rain holds off, I'll try again before dark and mess with the "trim" in the configtool.

3D Robotics
Comment by Chris Anderson on May 9, 2009 at 3:46pm
And when you pitch the nose down, the elevator goes up and vice-versa? Also for the roll?
Comment by Bryan Cuervo on May 9, 2009 at 6:35pm
I downloaded the latest 2.1 code today, flew again with a few changes and finally got stable flight!

Comment by Bryan Cuervo on May 9, 2009 at 6:42pm
The WP path flown today with the 2.1 code is just an 800' path square. Still needs a lot of tuning but at least she's flying stable.

The following WP was flown with the 2.0 code.


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