Matthieu LABAN
.NET, My Life, Flight Simulation and Real Flight...

 
About Me :
25 Years old developer and aviation
enthusiast living in Santa Clara, California.
View Matthieu Laban's profile on LinkedIn 
Contact me at :
mlaban at gmail dot com


Photo & Video Galleries:
- Gallery List
- Flight Videos
Resume :
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Playing with Silverlight... 

Silverlight 2.0 Beta 1 was released on Wednesday and I've had some time to play with it. I coded two application, one that connects to my website and retreive all the comments posted by my fellow readers, and another more amusing one, a small minigame...

Minigame...

Click on the image to get to the game page!
(Silverlight Beta1 can be installed from the game page, it's a really compact download and quick install)

I've included the source code. It might not be super optimized, super smart, super kewl... but somebody might find it useful...

Click here to download the source code

If you are a silverlight guru and know a better silverlighty way of doing things better that how I did, let me know! :)

Autopilot Fighting with the Wind 

Two quick videos before going to bed...

I worked on the Autopilot today... trying to get rid of the shimmering/stuttering effect in the yoke whenever the autopilot was in control. I solved this problem by fixing a long time bug which had the animations of the control surfaces and moving parts tied to the joystick rather than the actual physical damped values set by the flight model.

The way the controls are moved in a different manner for each airplane is done via a simple delayed response with non linear interpolation from the joystick inputs multiplied by a scalar on the input value. The delay is independant for each control surface, so the longer the delay, the slower the aircraft will respond to a user input from the joystick.
An aircraft with a fast response would be an aerobatic airplane, and an airplane with a slower response could be a Cessna, Piper, or even slower for an airliner...

But the jitteriness was not only due to that animation bug, there was another problem with the PID controllers... linked again to the chaining of two pid... the first pid had issues when calculating the derivative for small corrections, which made it output spikes, which in turn caused even more disturbance in the following PID...

I also made some changes to the wind/turbulence system, and the following video shows the Autopilot in action in severe turbulences. I could watch this video for hours... I love how the controls move on their own to counter the wind forces :-)
The second video shows the failure of the autopilot, I had set it to a low speed, with heavy turbulences... it shows how a turbulence that was a tiny bit too strong knocked the plane over and threw it in a spin... It's funny to see how the autopilot is still trying to recover hopelessly during the spin :-)

Just one note though, the airplane doesn't have an spin-out system, I just disconnected the autopilot and got out of it before it was too late!


Autopilot fighting... from Matt on Vimeo.

Severe Turbulences with Autopilot from Matt on Vimeo.

Silverlight 2 is coming... 

Silverlight 2 is coming... this is my dream come true... create desktop like experience in my favorite managed language, but on the web! (and cross platform!)

Beta 1 will be released next week during Mix08 in Las Vegas!

Scott Guthrie has a list of tutorials to demonstrate how to create a simple silverlight widget that connects to the Digg.com webservice.

I'm really impatient to try this new beta! I played with 1.0 and 1.1 but it was too javascipty for me and there was pretty much no support for built in controls. Silverlight 2 will come with a list of controls like buttons, lists, progress bars, images, video controls and even a datagrid (!), which is just what I need! (Hello Linq Queries!!)

This will be the opportunity to re-do the FSP's website draft which lead to the rant post about html last month... let's hope Silverlight helps me out with this!

G1000 Checkout! 

I finally had time to fly with an instructor at West Valley to complete my G1000 checkout and BFR. We flew for about an hour, played around with the G1000 (but looked outside 90% of the time ;)) did some stalls, slow flight, touch and goes, landings in different configurations, go around and used the autopilot a bit...

The 172SP G1000 is a very cool machine, it flies so much faster than the planes I usually fly in, and it is incredibly easy to control!

So two days ago, while I was watching Max Trescott's G1000 CD section about the KAP 140 (autopilot), I realized that the designers of the autopilot must have had the same problems as me... I mentionned in an earlier post that I had difficulties tweaking the autopilot PID's at low/high speeds... But here are the autopilot limitations:

Cessna 172R/S Autopilot Limitations
(Reference the appropriate PIM for the complete list of limitations)
Maximum Airspeed ........................................................... 140 KIAS
Minimum Airspeed .............................................................. 70 KIAS
Minimum Approach Speed.................................................. 80 KIAS
Maximum Flap Extension...................................................... 10 deg

How interesting! And thinking I was trying to make the AP work at 65kts or less with full flaps!! I should have come up with such limitations as well! And I will ;-)


So Bruno, when are you coming with me so I can teach you how to use the G1000 ? :)