Flightgear and Tx/Rx system

In the previous article the Flightgear's aircraft controlled using external program and in another article the Tx/Rx system connected to computer using Arduino. Today we will use those knowledges to connect Tx/Rx to Flightgear. Download the project from github and do the following steps.
1)Copy protocol files from Protocol/ to C:\Program Files (x86)\FlightGear\data\Protocol\
2)Compile and upload Rxreader/Rxreader.pde to the Arduino.

3)Connect Receiver to the Arduino

4)Run the C# program and connect to the Arduino and click to calibrate (this determines min-max values). When min-max values determined, finish the calibration.

5)Run Flightgear with the following arguments.

"C:\Program Files (x86)\FlightGear\bin\Win32\fgfs" ^
 "--fg-root=C:\Program Files (x86)\FlightGear\data" ^
 "--aircraft=Malolo1" ^
 "--generic=socket,out,10,127.0.0.1,49001,udp,outputprotocol" ^
 "--generic=socket,in,10,,49000,udp,inputprotocol" ^
 "--timeofday=noon"

6) Connect to Arduino, and connect the input and the output to Flightgear.

 

7)Try do not crash the airplane :)

That's all.

Flightgear: control aircraft externally

In the previous article the Flightgear program's some features were discussed. Today's topic will be about controlling aircraft through sockets from another program. There is a command line option "--generic" , which can be used for modifying items of property tree(see previous article, about http://localhost:1234).
Run the program with the following options.
The first generic argument means: Use sockets, for sending data out, 10 times a second, to the 127.0.0.1 machine(this is localhost's ip address), using the port 49001, use UDP protocol, the actual data which sent out are described in file "outputprotocol".
The second generic argument means: Use sockets again, for getting data from out, 10 times a second, skip the ip address, using the port 49000, use UDP protocol again, the coming data described in the file "inputprotocol".
If the program hangs, this means you are using the Flightgear version 2.0.0, which has a known bug and you need to downgrade to the version 1.9.1. Now if the hanging is over, then the program must give an error(see console's screen), because "outputprotocol" and "inputprotocol" files doesn't exists.
The following is "inputprotocol.xml" file's content, which describes 3 values, that the program will wait for input(aileron, elevator and throttle).
The following is "outputtprotocol.xml" file's content,which describes the same 3 values from input and plus one more (the speed of aircraft).
Now copy those files to the "C:\Program Files (x86)\FlightGear\data\Protocol" directory and run the program again. It will again give error(Error reading data), because no one send data to the input.
Now lets write a program in C#, which will send the input data to and receive output data from Flightgear. Add the controls to the main form as pictured in the screenshot:

We will use timer to send data in every 100ms(10 times in a second as described in the argument). This is sending part code: We will use threads to asynchronously get data from Flightgear. This is it:That's all.

Flightgear

Flightgear is open source flight simulator. It is weighted ~300MB for windows (relatively low compared to other simulators). It can be used not only for gaming. There are some R/C models, which can be used to practice on them. For example Malolo aircraft. Download and extract it to  C:\Program Files (x86)\FlightGear\data\Aircraft (Ubuntu: /usr/share/games/FlightGear/Aircraft/).
Then run the following from command line:
    "C:\Program Files (x86)\FlightGear\bin\Win32\fgfs" ^
        "--fg-root=C:\Program Files (x86)\FlightGear\data"  ^
        "--aircraft=Malolo1"
 or in Ubuntu
    fgfs --aircraft=Malolo1

Wait a minute, while the program finish loading, then you can drive the airplane using following keys.
    V                   : Change viewpoint
    Page-Up       : Increase throttle
    Page-Down  : Decrease throttle
    X                   : Zoom-in
    Shift-X          : Zoom-out
    Arrow keys   : Control elevator and aileron.
It is OK when you crash a plane just after a few seconds of flying :). Do some practice.

Flightgear has many useful features, and one of them is the ability to show the status of every components in the environment. Just run it adding the "--httpd=1234" argument and it creates a local web server. Navigating to http://localhost:1234 you can see a tree structure of all elements, which can be modified from browser also. For example start the program, change the viewpoint and navigate to http://localhost:1234/controls/engines/engine and click on throttle and change the value to 0.2.