Difference between revisions of "NPS"
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Revision as of 17:20, 17 January 2013
NPS contains a sensors model and can use Jsbsim as FDM (FlightDynamicModel) to allow fairly complex models. Other FDMs can be integrated easily.
- Compile paparazzi
cd paparazzi make
- Compile the vehicle
make AIRCRAFT=Quad_LisaM_2 clean_ac nps
- Start paparazzi_center if you want click to start programs
- Start messages to monitor the middleware activity ( from the tool menu of paparazzi center) or with
- Start the sim
You should now see activity in the "messages" window
- Plot the value of a message field.
start 'plotter' (Real-time plotter from the tool menu of paparazzi center) or with
for example drag the label 'int32 phi' from the ROTORCRAFT_FP message to the drawing area of the plotter
- Use the datalink to change the tlemetry mode
start 'settings' ( from the tool menu of paparazzi center) or with
./sw/ground_segment/tmtc/settings -ac Quad_LisaM_2
start 'server' to dispatch datalink messages ( from the tool menu of paparazzi center) or with
change the field "telemetry" on the first page to "Att loop" and send by pressing the green check button. The label on the left or the drop box should change to "Att loop" confirming your essage has been received. "message" should now show that the message "STAB_ATTITUDE_INT" is received
- Use flightgear to visualize your vehicle
If you want a view of a quadrotor in flightgear, make a link from /usr/share/games/flightgear/Models/Aircraft/paparazzi to PAPARAZZI_SRC/conf/simulator/flightgear/
sudo ln -s $PAPARAZZI_SRC/conf/simulator/flightgear/ /usr/share/games/flightgear/Models/Aircraft/paparazzi
start flighgear with
fgfs --fdm=null --native-gui=socket,in,30,,5501,udp --prop:/sim/model/path=Models/Aircraft/paparazzi/mikrokopter.xml
restart your simulator with
./var/Quad_LisaM_2/nps/simsitl --fg_host 127.0.0.1
- Save you session
- If you get an error like "JSBSim failed to open the configuration file: (null)/conf/simulator/jsbsim/aircraft/BOOZ2_A1.xml", you need to set your $PAPARAZZI_SRC and $PAPARAZZI_HOME environment variables. Add the following to your .bashrc, change paths according to where you put Paparazzi. Open a new terminal and launch the sim again.
export PAPARAZZI_SRC=~/paparazzi export PAPARAZZI_HOME=~/paparazzi
- If you did not install the jsbsim package your JSBSim installation under /opt/jsbsim will be used and you will have to set your library path (either in your shell startup file or when running the sim on the command line), e.g.:
LD_LIBRARY_PATH=/opt/jsbsim/lib ./var/Quad_LisaM_2/nps/simsitl --fg_host 127.0.0.1
Pausing or running the sim at a different speed
You can pause the simulation with CTRL-z in the terminal. You can then enter a different time factor (default 1.0) to make the simulation run slower or faster than real-time. Hit enter to resume the simulation or CTRL-z again to suspend it like any normal Unix process (use the fg (foreground) command to un-suspend it again).
Tunning the attitude control loop
Here we are going to use the simulator to demonstrate a way of tunning the attitude control loop.
- Restart your previous session
- Set telemetry mode to "Att loop"
- Display two real time plotter windows
In the first one, plot the field "m_phi" from the "STAB_ATTITUDE_int" message. This is our estimation of roll angle. On top of that, plot the field "phi" from the "STAB_ATTITUDE_REF_INT" message. This is our reference roll angle, that is, the roll value we are trying to achieve.
In the second plotter, plot the fields "delta_a_fb" and "delta_a_ff". Those are respectively the feddback and feedforward part of our roll command. The sum of those two terms is what is used as roll command.The feedforward part is the part used to follow our trajectory and the feedback part is the part used to reject perturbations.
- In "Settings", go to the "Att Loop" tab
We notice that the vehicle doesn't follow accurately the step trajectory we are trying to make him do.
Start by setting the value of the proportional gain ('pgain_phi') to 1000 instead of 400. The vehicle now follows the trajectory faster but overshoots. To prevent that, increase the value of the derivative gain ('dgain p') from 300 to 700.
If you look at the plotter where you're ploting the commands, you'll notice that during steps, the feedback command has to work hard. This means that our feedforward command is badly tunned, and namely not working hard enough.Increase the value of the feedforward gain ('ddgain p') from 300 to 540. You'll notice that now the feedback command has becomed marginal during the steps. This is the right value for the gain. Anything bigger will make the feedback command fight against the feedforward command during steps, anything smaller will make the feedback command have to complement the feedforward command.
- try starting flightgear with
fgfs --fdm=null --native-gui=socket,in,30,,5501,udp --prop:/sim/model/path=Models/Aircraft/paparazzi/simple_bipe.xml
an the sim with
./var/Quad_LisaM_2/nps/simsitl --fg_host 127.0.0.1 --rc_script 1
Use a Joystick
You can use a joystick (or connect your RC transmitter as a joystick) to control the quad in the simulator.
./var/Quad_LisaM_2/nps/simsitl --fg_host 127.0.0.1 -j
or, with a specific device index (0 is default):
./var/Quad_LisaM_2/nps/simsitl --fg_host 127.0.0.1 --js_dev 0
Joystick support uses the Simple DirectMedia Layer (SDL) library. Rather than specifying an input device name as one normally does on Linux, you just supply an index value (0, 1, 2,...) of the device you wish to use. Typically, the order of devices is the order in which you plugged them into your computer. The sim will display the name of the device being used to double check. If the -j option is used with no argument, the sim defaults to using device on index 0 (which is usually correct if you have only one joystick attached).