[ Concept 60 in the sky ]


Pilot: Aaron Kahn
Curator: Trammell Hudson
Recorder: Holly Fabre
Camera: Joe Easley
Location: Charles County RC Field
Equipment: Concept 60
Board level: Rev 2.2 with CVS head as of 2002-09-22
iPAQ software: Flyer and Attitude from CVS head

Joe Easly made movies! They're Quicktime, so you'll need the new mplayer to view under Linux. I'm not sure which flights these correspond to, but they're fun to watch. Without Joe telling us when the autopilot is engaged, it is hard to tell the difference. It really is working that well!

This is the second day of autonomous flight with the flyer program doing attitude hold and attitude command mode. We had eight flights, with over twenty minutes of autonomous hovering. I haven't had time to produce good graphs from each flights since the output format has changed from the previous flights.

Flight 1

Pitch attitude control tests showed that the 2 deg limits on the controller were too small. The controller hit its "stops" while trying to maintain its attitude.

Flight 2

We increased the pitch control limits to 3.5 degrees and the roll limits to 4 degrees. We also fixed the sign on the roll control feedback. Aaron noticed the sign on the roll feedback was backwards, so we fixed it. The flight ended with a gust of wind sending us backwards too quickly, so Aaron took back manual control.

[ Roll commands and response ]

Flight 3

Roll tests on this flight were fine and showed no significant divergence. It hovered for two minutes through significant wind gusts with no problems. We eventually got bored and had to refuel.

Flight 4

We enabled both pitch and roll for this flight. It did a great job, but quickly maxed out the controller's limits due to the wind. Aaron couldn't get enough attitude deflection to overcome it quickly, so the helicopter sort of wallowed about.

After three minutes of hovering, we let it try a landing. Aaron eased the collective down to about six inches, then dropped it to plant the skids. The roll controller tried to maintain the hoveirng, skid-low attitude and maxed out its limits. We'll need a squat switch or something to disconnect the autopilot after landing.

Flight 5

We increased both pitch and roll authority limits to 5 degrees. This helped out quite a bit. We did a 2 minute hover that drifted aways, then flew back manually. Aaron re-engaged the autopilot and let it hover for another two minutes. He did another auto landing.

Flight 6

We increased the attitude command authority for Aaron from 5 to +/- 8 degrees. This produced more snappy controls, rather than the slower response that the lower settings allowed. We then flew an entire tank of fuel all the way to an automatic landing.

Flight 7

This time we tried to add a small amount of integrator state to the attitude controller. The roll axis PID loop was set to I=0.1 and the pitch I=0.06. Aaron let it hover for ten seconds, but the integrators added quite a bit of instability. He brought it down and we disabled the integrators.

Flight 8

With the integrators off, Aaron took off and had the aircraft do some high speed maneuvers. He also tried giving it impulses to see how well it could recover. The controllers recovered well for forward pitch and left roll, but backwards pitch and right roll did not recover quickly. After burning a full tank of fuel, Aaron let it autoland and we called it a good day. -->
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