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A320-family/Nasal/Systems/brakesystem.nas
Josh Davidson d40bdc5444 Files: 2023
2022-12-31 12:56:08 -05:00

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# A3XX Autobrake and Braking
# Joshua Davidson (Octal450)
# Copyright (c) 2023 Josh Davidson (Octal450)
##########################################################################
# Simple Brake Simulation System
# 2010, Thorsten Brehm
#
# Simple simulation of brake energy absorption and cooling effects.
#
# This module computes (approximates... :-) ) an energy level which
# (faintly) resembles the kinetic energy absorption and cooling effects
# of a brake system. But instead of computing real temperatures, this
# is just meant to distinguish normal energy levels from exceptionally
# high levels. The target is to drive EICAS "brakes overheat" messages
# and gear effects only, to "reward" pilots with exceptionally bad
# landings...
#
# To avoid complicated calculations of different braking effects (roll/air
# drag, reverse thrust etc), we simply assume the brake system to cause a
# fixed deceleration (me.BrakeDecel). With this deceleration we approximate
# the speed difference which would be caused by the brake system alone for
# any given simulation interval. The difference of the kinetic energy level
# at the current speed and the decelerated speed are then added up to the
# total absorbed brake energy.
# Units (knots/lbs/Kg) do not matter much here. Eventually a magic scaling
# divisor is used to scale the output level. Any output > 1 means
# "overheated brakes", any level <=1 means "brake temperature OK".
# No exact science here - but good enough for now :-).
##########################################################################
#
# Added brakes temp calculations and adapted for A320-family
# 2020, Andrea Vezzali
# Updated Nasal to project standards
# 2020, Jonathan Redpath
##########################################################################
var LThermalEnergy = 0;
var RThermalEnergy = 0;
var dt = 0;
var LBrakeLevel = 0;
var RBrakeLevel = 0;
var tatdegc = 0;
var L_thrust = 0;
var R_thrust = 0;
var airspeed = 0;
var BrakeSystem =
{
new : func()
{
var m = { parents : [BrakeSystem]};
# deceleration caused by brakes alone (knots/s2)
m.BrakeDecel = 1.0; # kt/s^2
# Higher value means quicker cooling
m.CoolingFactor = 0.000125;
# Scaling divisor. Use this to scale the energy output.
# Manually tune this value: a total energy output
# at "/gear/brake-thermal-energy" > 1.0 means overheated brakes,
# anything below <= 1.0 means energy absorbed by brakes is OK.
#m.ScalingDivisor= 700000*450.0;
m.ScalingDivisor = 0.000000006;
m.LSmokeActive = 0;
m.LSmokeToggle = 0;
m.RSmokeActive = 0;
m.RSmokeToggle = 0;
m.thermalEnergy = [0.0, 0.0];
m.brakeFans = props.globals.getNode("/controls/gear/brake-fans");
m.fireServices = props.globals.getNode("/sim/animation/fire-services");
m.gearSmoke = [props.globals.getNode("/gear/gear[1]/Lbrake-smoke"), props.globals.getNode("/gear/gear[2]/Rbrake-smoke")];
m.lBrakeTemp = [props.globals.getNode("/gear/gear[1]/L1brake-temp-degc"),props.globals.getNode("/gear/gear[1]/L2brake-temp-degc")];
m.rBrakeTemp = [props.globals.getNode("/gear/gear[2]/R3brake-temp-degc"),props.globals.getNode("/gear/gear[2]/R4brake-temp-degc")];
m.L1error = 0;
m.L2error = 0;
m.R3error = 0;
m.R4error = 0;
m.counter = 0;
return m;
},
reset : func()
{
# Initial thermal energy
me.thermalEnergy[0] = 0.0;
me.thermalEnergy[1] = 0.0;
me.brakeFans.setValue(0);
me.gearSmoke[0].setValue(0);
me.gearSmoke[1].setValue(0);
me.fireServices.setValue(0);
#Introducing a random error on temp sensors (max 5°C)
me.L1error = math.round(rand()*(5));
me.L2error = math.round(rand()*(5));
me.R3error = math.round(rand()*(5));
me.R4error = math.round(rand()*(5));
var tatdegc = pts.Fdm.JSBsim.Propulsion.tatC.getValue() or 0;
me.lBrakeTemp[0].setValue(tatdegc+me.L1error);
me.lBrakeTemp[1].setValue(tatdegc+me.L2error);
me.rBrakeTemp[0].setValue(tatdegc+me.R3error);
me.rBrakeTemp[1].setValue(tatdegc+me.R4error);
me.LastSimTime = 0.0;
},
# update brake energy
update : func(notification)
{
if (me.counter == 0) {
me.counter = 1;
} else {
me.counter = 0;
return;
}
LThermalEnergy = me.thermalEnergy[0];
RThermalEnergy = me.thermalEnergy[1];
me.CurrentTime = notification.elapsedTime;
dt = me.CurrentTime - me.LastSimTime;
LBrakeLevel = notification.leftBrakeFCS;
RBrakeLevel = notification.rightBrakeFCS;
tatdegc = pts.Fdm.JSBsim.Propulsion.tatC.getValue() or 0;
if (pts.Sim.replayState.getValue() == 0 and dt < 1.0) {
#cooling effect: adjust cooling factor by a value proportional to the environment temp (m.CoolingFactor + environment temp-degc * 0.00001)
var LCoolingRatio = me.CoolingFactor+(tatdegc*0.000001);
var RCoolingRatio = me.CoolingFactor+(tatdegc*0.000001);
if (me.brakeFans.getValue()) {
#increase CoolingRatio if Brake Fans are active
LCoolingRatio = LCoolingRatio * 3;
RCoolingRatio = RCoolingRatio * 3;
};
airspeed = notification.airspeedV;
if (pts.Gear.position[1].getValue()) {
#increase CoolingRatio if gear down according to airspeed
LCoolingRatio = LCoolingRatio * airspeed;
} else {
#Reduced CoolingRatio if gear up
LCoolingRatio = LCoolingRatio * 0.1;
};
if (pts.Gear.position[2].getValue()) {
#increase CoolingRatio if gear down according to airspeed
RCoolingRatio = RCoolingRatio * airspeed;
} else {
#Reduced CoolingRatio if gear up
RCoolingRatio = RCoolingRatio * 0.1;
};
if (LBrakeLevel>0) {
#Reduced CoolingRatio if Brakes used
LCoolingRatio = LCoolingRatio * 0.1 * LBrakeLevel;
};
if (RBrakeLevel>0) {
#Reduced CoolingRatio if Brakes used
RCoolingRatio = RCoolingRatio * 0.1 * RBrakeLevel;
};
var LnCoolFactor = math.ln(1-LCoolingRatio);
var RnCoolFactor = math.ln(1-RCoolingRatio);
# disabled thrust effect
L_Thrust = 0;
R_Thrust = 0;
if (notification.gear1Wow) {
var V1 = pts.Velocities.groundspeedKt.getValue();
var Mass = pts.Fdm.JSBsim.Inertia.weightLbs.getValue() * me.ScalingDivisor;
# absorb some kinetic energy:
# dE= 1/2 * m * V1^2 - 1/2 * m * V2^2)
var V2_L = V1 - me.BrakeDecel * dt * LBrakeLevel;
var V2_R = V1 - me.BrakeDecel * dt * RBrakeLevel;
LThermalEnergy += (Mass * pts.Gear.compression[1].getValue() * (math.pow(V1, 2) - math.pow(V2_L, 2)) / 2);
if (pts.Services.Chocks.enable.getValue()) {
if (!notification.parkingBrake) {
# cooling effect: reduce thermal energy by (LnCoolFactor) * dt
LThermalEnergy = LThermalEnergy * math.exp(LnCoolFactor * dt);
} else {
#LThermalEnergy += L_Thrust;
# cooling effect: reduce thermal energy by (LnCoolFactor) * dt
LThermalEnergy = (LThermalEnergy * math.exp(LnCoolFactor * dt)) + (L_Thrust * dt);
};
} else {
if (!notification.parkingBrake) {
if (LBrakeLevel>0) {
if (V2_L>0) {
#LThermalEnergy += (Mass * (math.pow(V1, 2) - math.pow(V2_L, 2)) / 2) + L_thrust;
# cooling effect: reduce thermal energy by (LnCoolFactor) * dt
LThermalEnergy = LThermalEnergy * math.exp(LnCoolFactor * dt);
} else {
#LThermalEnergy += math.abs(L_Thrust);
# cooling effect: reduce thermal energy by (LnCoolFactor) * dt
LThermalEnergy = (LThermalEnergy * math.exp(LnCoolFactor * dt)) + (L_Thrust * dt);
};
} else {
# cooling effect: reduce thermal energy by (LnCoolFactor) * dt
LThermalEnergy = LThermalEnergy * math.exp(LnCoolFactor * dt);
};
} else {
#LThermalEnergy += math.abs(L_Thrust);
# cooling effect: reduce thermal energy by (LnCoolFactor) * dt
LThermalEnergy = (LThermalEnergy * math.exp(LnCoolFactor * dt)) + (L_Thrust * dt);
};
};
RThermalEnergy += (Mass * pts.Gear.compression[2].getValue() * (math.pow(V1, 2) - math.pow(V2_R, 2)) / 2);
if (pts.Services.Chocks.enable.getValue()) {
if (!notification.parkingBrake) {
# cooling effect: reduce thermal energy by (RnCoolFactor) * dt
RThermalEnergy = RThermalEnergy * math.exp(RnCoolFactor * dt);
} else {
#RThermalEnergy += math.abs(R_Thrust);
# cooling effect: reduce thermal energy by (RnCoolFactor) * dt
RThermalEnergy = (RThermalEnergy * math.exp(RnCoolFactor * dt)) + (R_Thrust * dt);
};
} else {
if (!notification.parkingBrake) {
if (RBrakeLevel>0) {
if (V2_R>0) {
#RThermalEnergy += (Mass * (math.pow(V1, 2) - math.pow(V2_R, 2)) / 2) + R_thrust;
# cooling effect: reduce thermal energy by (RnCoolFactor) * dt
RThermalEnergy = RThermalEnergy * math.exp(RnCoolFactor * dt);
} else {
#RThermalEnergy += math.abs(R_Thrust);
# cooling effect: reduce thermal energy by (RnCoolFactor) * dt
RThermalEnergy = (RThermalEnergy * math.exp(RnCoolFactor * dt)) + (R_Thrust * dt);
};
} else {
# cooling effect: reduce thermal energy by (RnCoolFactor) * dt
RThermalEnergy = RThermalEnergy * math.exp(RnCoolFactor * dt);
};
} else {
#RThermalEnergy += math.abs(R_Thrust);
# cooling effect: reduce thermal energy by (RnCoolFactor) * dt
RThermalEnergy = (RThermalEnergy * math.exp(RnCoolFactor * dt)) + (R_Thrust * dt);
};
};
} else {
LThermalEnergy = LThermalEnergy * math.exp(LnCoolFactor * dt);
RThermalEnergy = RThermalEnergy * math.exp(RnCoolFactor * dt);
};
if (LThermalEnergy < 0) {
LThermalEnergy = 0
};
if (LThermalEnergy > 3) {
LThermalEnergy = 3
};
if (RThermalEnergy < 0) {
RThermalEnergy = 0
};
if (RThermalEnergy > 3) {
RThermalEnergy = 3
};
me.thermalEnergy[0] = LThermalEnergy;
me.thermalEnergy[1] = RThermalEnergy;
#Calculating Brakes temperature
me.lBrakeTemp[0].setValue(tatdegc+me.L1error+(LThermalEnergy * (300-tatdegc-me.L1error)));
me.lBrakeTemp[1].setValue(tatdegc+me.L2error+(LThermalEnergy * (300-tatdegc-me.L2error)));
me.rBrakeTemp[0].setValue(tatdegc+me.R3error+(RThermalEnergy * (300-tatdegc-me.R3error)));
me.rBrakeTemp[1].setValue(tatdegc+me.R4error+(RThermalEnergy * (300-tatdegc-me.R4error)));
if (LThermalEnergy>1 and !me.LSmokeActive) {
# start smoke processing
me.LSmokeActive = 1;
settimer(func { BrakeSys.Lsmoke(); },0); # is settimer needed?
};
if (RThermalEnergy>1 and !me.RSmokeActive) {
# start smoke processing
me.RSmokeActive = 1;
settimer(func { BrakeSys.Rsmoke(); },0);
};
};
me.LastSimTime = me.CurrentTime;
},
# smoke processing
Lsmoke : func()
{
if (me.LSmokeActive and me.thermalEnergy[0] > 1) {
# make density of smoke effect depend on energy level
var LSmokeDelay = 0;
var LThermalEnergy = me.thermalEnergy[0];
if (LThermalEnergy < 1.5) {
LSmokeDelay = (1.5 - LThermalEnergy);
};
# No smoke when gear retracted
var LSmokeValue = (pts.Gear.position[1].getValue() > 0.5);
# toggle smoke to interpolate different densities
if (LSmokeDelay > 0.05) {
me.LSmokeToggle = !me.LSmokeToggle;
if (!me.LSmokeToggle)
LSmokeValue = 0;
else
LSmokeDelay = 0;
};
me.gearSmoke[0].setValue(LSmokeValue);
settimer(func { BrakeSys.Lsmoke(); },LSmokeDelay);
} else {
# stop smoke processing
me.gearSmoke[0].setValue(0);
me.LSmokeActive = 0;
};
if (me.thermalEnergy[0] > 1.5) {
me.fireServices.setValue(1);
} else {
me.fireServices.setValue(0);
};
},
# smoke processing
Rsmoke : func()
{
if (me.RSmokeActive and me.thermalEnergy[1] > 1) {
# make density of smoke effect depend on energy level
var RSmokeDelay = 0;
var RThermalEnergy = me.thermalEnergy[1];
if (RThermalEnergy < 1.5) {
RSmokeDelay = (1.5 - RThermalEnergy);
};
# No smoke when gear retracted
var RSmokeValue = (pts.Gear.position[2].getValue() > 0.5);
# toggle smoke to interpolate different densities
if (RSmokeDelay > 0.05) {
me.RSmokeToggle = !me.RSmokeToggle;
if (!me.RSmokeToggle)
RSmokeValue = 0;
else
RSmokeDelay = 0;
};
me.gearSmoke[1].setValue(RSmokeValue);
settimer(func { BrakeSys.Rsmoke(); },RSmokeDelay);
} else {
# stop smoke processing
me.gearSmoke[1].setValue(0);
me.RSmokeActive = 0;
};
if (me.thermalEnergy[1] > 1.5) {
me.fireServices.setValue(1);
} else {
me.fireServices.setValue(0);
};
},
};
var BrakeSys = BrakeSystem.new();
#############
# Autobrake #
#############
var Autobrake = {
active: props.globals.initNode("/controls/autobrake/active", 0, "BOOL"),
mode: props.globals.initNode("/controls/autobrake/mode", 0, "INT"),
decel: props.globals.initNode("/controls/autobrake/decel-rate", 0, "DOUBLE"),
_wow0: 0,
_gnd_speed: 0,
_mode: 0,
_active: 0,
init: func() {
me.active.setBoolValue(0);
me.mode.setValue(0);
me.decel.setValue(0);
},
arm_autobrake: func(mode) {
me._wow0 = pts.Gear.wow[0].getBoolValue();
me._gnd_speed = pts.Velocities.groundspeedKt.getValue();
if (mode == 0) { # OFF
absChk.stop();
if (me.active.getBoolValue()) {
me.active.setBoolValue(0);
pts.Controls.Gear.brake[0].setValue(0);
pts.Controls.Gear.brake[1].setValue(0);
}
me.decel.setValue(0);
me.mode.setValue(0);
} else if (mode == 1 and !me._wow0) { # LO
me.decel.setValue(2.0);
me.mode.setValue(1);
absChk.start();
} else if (mode == 2 and !me._wow0) { # MED
me.decel.setValue(3);
me.mode.setValue(2);
absChk.start();
} else if (mode == 3 and me._wow0 and me._gnd_speed < 40) { # MAX
me.decel.setValue(6);
me.mode.setValue(3);
absChk.start();
}
},
loop: func() {
me._wow0 = pts.Gear.wow[0].getBoolValue();
me._gnd_speed = pts.Velocities.groundspeedKt.getValue();
me._mode = me.mode.getValue();
me._active = me.active.getBoolValue();
if (me._gnd_speed > 72) {
if (me._mode != 0 and systems.FADEC.detent[0].getValue() == 0 and systems.FADEC.detent[1].getValue() == 0 and me._wow0 and systems.HYD.Switch.nwsSwitch.getBoolValue() and systems.HYD.Psi.green.getValue() >= 2500 ) {
me.active.setBoolValue(1);
} elsif (me._active) {
me.active.setBoolValue(0);
pts.Controls.Gear.brake[0].setValue(0);
pts.Controls.Gear.brake[1].setValue(0);
}
}
if (me._mode == 3 and pts.Controls.Gear.lever.getValue() == 0) {
me.arm_autobrake(0);
}
if (me._mode != 0 and me._wow0 and me._active and (pts.Controls.Gear.brake[0].getValue() > 0.05 or pts.Controls.Gear.brake[1].getValue() > 0.05)) {
me.arm_autobrake(0);
}
},
};
# Override FG's generic brake
controls.applyBrakes = func(v, which = 0) {
if (!pts.Acconfig.running.getBoolValue()) {
if (which <= 0) {
pts.Controls.Gear.brake[0].setValue(v);
}
if (which >= 0) {
pts.Controls.Gear.brake[1].setValue(v);
}
}
}
# Autobrake loop
var absChk = maketimer(0.2, func {
Autobrake.loop();
});
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