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use sideslip for heading offset in-air, and heading change rate on-ground.

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Unfortunately, this is quite jittery on some aircraft, so it uses a slower
lowpass filter. I'd like to fix that, but don't even know what causes it.
Considering /sim/time/delta-realtime-sec didn't help.  :-/
This commit is contained in:
mfranz 2006-08-19 22:24:24 +00:00
parent 8ac2c6a674
commit 07f5dd24f3
1 changed files with 62 additions and 15 deletions
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77
Nasal/dynamic_view.nas
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@ -6,6 +6,32 @@ nsigmoid = func(x) { 2 / (1 + math.exp(-x)) - 1 }
pow = func(v, w) { math.exp(math.ln(v) * w) }
npow = func(v, w) { math.exp(math.ln(abs(v)) * w) * (v < 0 ? -1 : 1) }
clamp = func(v, min, max) { v < min ? min : v > max ? max : v }
normatan = func(x) { math.atan2(x, 1) * 2 / math.pi }
f1 = func(x) { 3.782 * math.sin(x) * math.sin(x) * math.exp(-x) }
f2 = func(x) { 2 * sin(x) / (x * x * x + 1) }
f3 = func(x) { 1 / (x * x + 1) }
# Class that implements EWMA (Exponentially Weighted Moving Average)
# lowpass filter. Initialize with coefficient, set new value when
# you fetch one.
#
LowPass = {
new : func(coeff) {
var m = { parents : [LowPass] };
m.value = nil;
m.coeff = 1.0 - 1.0 / pow(10, abs(coeff));
return m;
},
get : func(v) {
me.get = me._get_;
me.value = v;
},
_get_ : func(v) {
me.value = v * (1 - me.coeff) + me.value * me.coeff;
},
};
@ -82,6 +108,10 @@ ViewManager = {
m.headingN = props.globals.getNode("/orientation/heading-deg", 1);
m.pitchN = props.globals.getNode("/orientation/pitch-deg", 1);
m.rollN = props.globals.getNode("/orientation/roll-deg", 1);
m.slipN = props.globals.getNode("/orientation/side-slip-deg", 1);
m.wind_dirN = props.globals.getNode("/environment/wind-from-heading-deg", 1);
m.wind_speedN = props.globals.getNode("/environment/wind-speed-kt", 1);
m.heading_axis = ViewAxis.new("/sim/current-view/goal-heading-offset-deg");
m.pitch_axis = ViewAxis.new("/sim/current-view/goal-pitch-offset-deg");
@ -89,16 +119,19 @@ ViewManager = {
# accerations are converted to G (one G is subtraced from z-accel)
m.ax = Input.new("/accelerations/pilot/x-accel-fps_sec", 0.03108095, 0, 1.1, 0);
m.ay = Input.new("/accelerations/pilot/y-accel-fps_sec", 0.03108095, 0, 1.1);
m.ay = Input.new("/accelerations/pilot/y-accel-fps_sec", 0.03108095, 0, 1.3);
m.az = Input.new("/accelerations/pilot/z-accel-fps_sec", -0.03108095, -1, 1.0073);
# velocities are converted to knots
m.vx = Input.new("/velocities/uBody-fps", 0.5924838, 0);
m.vx = Input.new("/velocities/uBody-fps", 0.5924838, 0, 1);
m.vy = Input.new("/velocities/vBody-fps", 0.5924838, 0);
m.vz = Input.new("/velocities/wBody-fps", 0.5924838, 0);
# turn WoW bool into smooth values ranging from -1 to 1
m.wow = Input.new("/gear/gear/wow", 2, -1, 1.2);
m.wow = Input.new("/gear/gear/wow", 1, 0, 1.2);
m.hdg_chg_rate = LowPass.new(1.3);
m.last_heading = m.headingN.getValue();
m.size_factor = -getprop("/sim/chase-distance-m") / 25;
m.reset();
return m;
},
@ -117,22 +150,36 @@ ViewManager = {
var roll = me.rollN.getValue();
var wow = me.wow.get();
var ax = me.ax.get();
var ay = me.ay.get();
# var ax = me.ax.get();
# var ay = me.ay.get();
var az = me.az.get();
var adir = math.atan2(-ay, ax) * 180 / math.pi;
var aval = math.sqrt(ax * ax + ay * ay);
# var adir = math.atan2(ay, ax) * 180 / math.pi;
# var aval = math.sqrt(ax * ax + ay * ay);
#var vx = me.vx.get();
#var vy = me.vy.get();
#var vdir = math.atan2(vy, vx) * 180 / math.pi;
#var vval = math.sqrt(vx * vx + vy * vy);
# var vx = me.vx.get();
# var vy = me.vy.get();
# var vdir = math.atan2(vy, vx) * 180 / math.pi;
# var vval = math.sqrt(vx * vx + vy * vy);
var steering = 80 * wow * nsigmoid(adir * 5.5 / 180) * nsigmoid(aval);
# var wspd = me.wind_speedN.getValue();
# var wdir = me.headingN.getValue() - me.wind_dirN.getValue();
# var u = vx - wspd * cos(wdir);
var hdg = me.headingN.getValue();
var hdiff = me.last_heading - hdg;
me.last_heading = hdg;
while (hdiff >= 180) {
hdiff -= 360;
}
while (hdiff < -180) {
hdiff += 360;
}
var steering = 40 * normatan(me.hdg_chg_rate.get(hdiff)) * me.size_factor;
me.heading_axis.apply( # heading ...
-20 * sin(roll) * cos(pitch) # due to roll
+ steering # due to accleration (also ground steering)
-15 * sin(roll) * cos(pitch) # due to roll
+ steering * wow # due to ground steering
+ 0.5 * me.slipN.getValue() * (1 - wow) # due to sideslip
);
me.pitch_axis.apply( # pitch ...
10 * sin(roll) * sin(roll) # due to roll
@ -142,7 +189,6 @@ ViewManager = {
me.roll_axis.apply(0 # roll ...
#0.0 * sin(roll) * cos(pitch) # due to roll (none)
);
},
};
@ -195,6 +241,7 @@ settimer(func {
props.globals.getNode("/accelerations/pilot/x-accel-fps_sec", 1).setDoubleValue(0);
props.globals.getNode("/accelerations/pilot/y-accel-fps_sec", 1).setDoubleValue(0);
props.globals.getNode("/accelerations/pilot/z-accel-fps_sec", 1).setDoubleValue(-32);
props.globals.getNode("/orientation/side-slip-deg", 1).setDoubleValue(0);
props.globals.getNode("/gear/gear/wow", 1).setBoolValue(1);
# let listeners keep some variables up-to-date, so that they don't have