191 lines
6.8 KiB
Text
191 lines
6.8 KiB
Text
# This is a small script that adjusts autopilot target values to track
|
|
# (fly in formation with) an AI or Multiplayer aircraft.
|
|
|
|
# Quick start instructions:
|
|
#
|
|
#
|
|
# 1. Copy this file into $FGROOT/data/Nasal (along with the other
|
|
# system nasal scripts.)
|
|
#
|
|
# 2. Start up FlightGear selecting an airplane with a reasonably configured
|
|
# autopilot that responds to and works with the standard autopilot
|
|
# dialog box (F11). The MiG 15 is one that works, the 777-200 works,
|
|
# the Citation Bravo does not work, the default c172 probably does not
|
|
# work, etc.
|
|
#
|
|
# 3. Take off and establish stable flight.
|
|
#
|
|
# 4. Open the property browser (File->Browse Internal Properties) and navigate
|
|
# to /ai/models/ Choose one of the available aircraft[] or multiplayer[]
|
|
# entries. You can look at all those subtrees to find the call sign you
|
|
# want. Also note that the subtree for each entity has a radar area that
|
|
# will show range and offset from your current heading.
|
|
#
|
|
# 5. Open a second property browser window (upper left click box in the first
|
|
# property browser window.) Navigate to /autopilot/target-tracking/
|
|
#
|
|
# 6. Set "/autopilot/target-tracking/target-root" to point to the entity
|
|
# path you discovered in step #4. For instance, this should be set to
|
|
# something like /ai/models/multiplayer[2] or /ai/models/aircraft[0]
|
|
#
|
|
# 7. Set "/autopilot/target-tracking/goal-range-nm" to the follow distance
|
|
# you want.
|
|
#
|
|
# 8. Set "/autopilot/target-tracking/enable" = 1, this will turn on the radar
|
|
# computation for each ai/multiplayer entity and will tell the tracking
|
|
# script to start updating the autopilot settings.
|
|
#
|
|
# 9. Open up the autopilot configuration window (F11) and activate any of the
|
|
# heading, pitch, and speed axes. The script will begin updating the heading
|
|
# bug angle, the "speed with throttle" value, and the "altitude hold" value.
|
|
#
|
|
# 10. You can choose to mix and match any of the autopilot modes you want, i.e.
|
|
# you could turn off the heading control and turn manually while the system
|
|
# holds speed and altitude for you.
|
|
#
|
|
# 11. It always helps to have a sensible target arcraft to chase. You are
|
|
# flying within the turn radius and climb rate limits of your autopilot.
|
|
#
|
|
# Don't forget you are pilot in command and at all times responsible for
|
|
# maintaining safe airspeed and altitude.
|
|
#
|
|
# Enjoy the ride!
|
|
|
|
|
|
print("Target Tracking script loading ...");
|
|
|
|
# script defaults (configurable if you like)
|
|
default_update_period = 0.05;
|
|
default_goal_range_nm = 0.05;
|
|
default_target_root = "/ai/models/aircraft[0]";
|
|
default_min_speed_kt = 120;
|
|
|
|
# master enable switch
|
|
target_tracking_enable = 0;
|
|
|
|
# update period
|
|
update_period = default_update_period;
|
|
|
|
# goal range to acheive when following target
|
|
goal_range_nm = 0;
|
|
|
|
# minimum speed so we don't drop out of the sky
|
|
min_speed_kt = 0;
|
|
|
|
# Target property tree root
|
|
target_root = "";
|
|
|
|
# Initialize target tracking
|
|
TrackInit = func {
|
|
target_tracking_enable = getprop("/autopilot/target-tracking/enable");
|
|
if ( target_tracking_enable == nil ) {
|
|
target_tracking_enable = 0;
|
|
setprop("/autopilot/target-tracking/enable", target_tracking_enable);
|
|
}
|
|
|
|
update_period = getprop("/autopilot/target-tracking/update-period");
|
|
if ( update_period == nil ) {
|
|
update_period = default_update_period;
|
|
setprop("/autopilot/target-tracking/update-period", update_period);
|
|
}
|
|
|
|
goal_range_nm = getprop("/autopilot/target-tracking/goal-range-nm");
|
|
if ( goal_range_nm == nil ) {
|
|
goal_range_nm = default_goal_range_nm;
|
|
setprop("/autopilot/target-tracking/goal-range-nm", goal_range_nm);
|
|
}
|
|
|
|
min_speed_kt = getprop("/autopilot/target-tracking/min-speed-kt");
|
|
if ( min_speed_kt == nil ) {
|
|
min_speed_kt = default_min_speed_kt;
|
|
setprop("/autopilot/target-tracking/min-speed-kt", min_speed_kt);
|
|
}
|
|
|
|
target_root = getprop("/autopilot/target-tracking/target-root");
|
|
if ( target_root == nil ) {
|
|
target_root = default_target_root;
|
|
setprop("/autopilot/target-tracking/target-root", target_root);
|
|
}
|
|
}
|
|
settimer(TrackInit, 0);
|
|
|
|
|
|
# If enabled, update our AP target values based on the target range,
|
|
# bearing, and speed
|
|
TrackUpdate = func {
|
|
target_tracking_enable = getprop("/autopilot/target-tracking/enable");
|
|
update_period = getprop("/autopilot/target-tracking/update-period");
|
|
|
|
if ( target_tracking_enable == 1 ) {
|
|
# refresh user configurable values
|
|
goal_range_nm = getprop("/autopilot/target-tracking/goal-range-nm");
|
|
target_root = getprop("/autopilot/target-tracking/target-root");
|
|
|
|
# force radar debug-mode on (forced radar calculations even if
|
|
# no radar instrument and ai aircraft are out of range
|
|
setprop("/instrumentation/radar/debug-mode", 1);
|
|
|
|
my_hdg_prop = sprintf("/orientation/heading-magnetic-deg" );
|
|
my_hdg = getprop(my_hdg_prop);
|
|
|
|
my_hdg_true_prop = sprintf("/orientation/heading-deg" );
|
|
my_hdg_true = getprop(my_hdg_true_prop);
|
|
|
|
alt_prop = sprintf("%s/position/altitude-ft", target_root );
|
|
alt = getprop(alt_prop);
|
|
if ( alt == nil ) {
|
|
print("bad property path: ", alt_prop);
|
|
return;
|
|
}
|
|
|
|
speed_prop = sprintf("%s/velocities/true-airspeed-kt", target_root );
|
|
speed = getprop(speed_prop);
|
|
if ( speed == nil ) {
|
|
print("bad property path: ", speed_prop);
|
|
return;
|
|
}
|
|
|
|
range_prop = sprintf("%s/radar/range-nm", target_root );
|
|
range = getprop(range_prop);
|
|
if ( range == nil ) {
|
|
print("bad property path: ", range_prop);
|
|
return;
|
|
}
|
|
|
|
h_offset_prop = sprintf("%s/radar/h-offset", target_root );
|
|
h_offset = getprop(h_offset_prop);
|
|
if ( h_offset == nil ) {
|
|
print("bad property path: ", h_offset_prop);
|
|
return;
|
|
}
|
|
|
|
if ( h_offset > -90 and h_offset < 90 ) {
|
|
# in front of us
|
|
range_error = range - goal_range_nm;
|
|
} else {
|
|
# behind us
|
|
range_error = goal_range_nm - range;
|
|
}
|
|
target_speed = speed + range_error * 100.0;
|
|
if ( target_speed < min_speed_kt ) {
|
|
target_speed = min_speed_kt;
|
|
}
|
|
|
|
setprop( "/autopilot/settings/target-altitude-ft", alt );
|
|
setprop( "/autopilot/settings/heading-bug-deg", my_hdg + h_offset );
|
|
setprop( "/autopilot/settings/true-heading-deg",
|
|
my_hdg_true + h_offset );
|
|
setprop( "/autopilot/settings/target-speed-kt", target_speed );
|
|
}
|
|
|
|
# last thing to do before we return from this function
|
|
registerTimer();
|
|
}
|
|
|
|
|
|
# timer handling to cause our update function to be called periodially
|
|
registerTimer = func {
|
|
settimer(TrackUpdate, update_period );
|
|
}
|
|
registerTimer();
|
|
|