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fgdata/Aircraft/c172p/Nasal/action-sim.nas

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##
# action-sim.nas Updates various simulated features every frame
##
# Initialize local variables
var H = nil;
var L = nil;
var phi = nil;
var C = nil;
# set up filters for these actions
var cdi0_lowpass = aircraft.lowpass.new(0.5);
var cdi1_lowpass = aircraft.lowpass.new(0.5);
var gs0_lowpass = aircraft.lowpass.new(0.5);
var gs1_lowpass = aircraft.lowpass.new(0.5);
# Properties
var propNav0 = props.globals.getNode("instrumentation/nav[0]", 1);
var propNav1 = props.globals.getNode("instrumentation/nav[1]", 1);
var navLights = props.globals.getNode("controls/lighting/nav-lights", 1);
var instrumentsNorm = props.globals.getNode("controls/lighting/instruments-norm", 1);
var instrumentLightFactor = props.globals.getNode("sim/model/material/instruments/factor", 1);
var panelLights = props.globals.getNode("controls/lighting/panel-norm", 1);
var dhN_ft = props.globals.getNode("gear/gear[0]/compression-ft", 1);
var dhR_ft = props.globals.getNode("gear/gear[2]/compression-ft", 1);
var dhL_ft = props.globals.getNode("gear/gear[1]/compression-ft", 1);
var propGear0 = props.globals.getNode("gear/gear[0]", 1);
var propGear1 = props.globals.getNode("gear/gear[1]", 1);
var propGear2 = props.globals.getNode("gear/gear[2]", 1);
# Associate Nodes
var cdiNAV0 = propNav0.getNode("heading-needle-deflection", 1);
var cdiNAV1 = propNav1.getNode("heading-needle-deflection", 1);
var gsNAV0 = propNav0.getNode("gs-needle-deflection-norm", 1);
var gsNAV1 = propNav1.getNode("gs-needle-deflection-norm", 1);
var filteredCDI0 = propNav0.getNode("filtered-cdiNAV0-deflection", 1);
var filteredCDI1 = propNav1.getNode("filtered-cdiNAV1-deflection", 1);
var filteredGS0 = propNav0.getNode("filtered-gsNAV0-deflection", 1);
var filteredGS1 = propNav1.getNode("filtered-gsNAV1-deflection", 1);
var nose_link_rot = propGear0.getNode("compression-rotation-deg", 1);
var left_main_rot = propGear1.getNode("compression-rotation-deg", 1);
var right_main_rot = propGear2.getNode("compression-rotation-deg", 1);
var init_actions = func {
filteredCDI0.setDoubleValue(0.0);
filteredCDI1.setDoubleValue(0.0);
filteredGS0.setDoubleValue(0.0);
filteredGS1.setDoubleValue(0.0);
# Make sure that init_actions is called when the sim is reset
setlistener("sim/signals/reset", init_actions);
# Request that the update fuction be called next frame
settimer(update_actions, 0);
}
var update_actions = func {
# Note: R2D and FT2M are unit conversion factors defined in $FG_ROOT/Nasal/globals.nas
# R2D (radians to degrees) FT2M (feet to meters)
##
# Compute the scissor link angles due to nose strut compression
##
var theta = 0.0;
# Compute the angle the nose gear scissor rotates due to nose gear strut compression
H = 0.240626; # Nose gear oleo strut extended length in m
L = 0.194716; # Nose gear scissor length in m
phi = 0.666058;
C = dhN_ft.getValue()*FT2M;
if (C > 0.0) {
theta = scissor_angle(H,C,L,phi)*R2D;
}
# Compute compression induced main gear rotations
#
# constants
var R_m = 0.919679;
var h0 = 0.63872;
var theta0_rad = 0.803068;
# Right main
var delta_h = dhR_ft.getValue()*FT2M;
var right_alpha_deg = ( math.acos( (h0 - delta_h)/R_m ) - theta0_rad )*R2D;
# Left main
var delta_h = dhL_ft.getValue()*FT2M;
var left_alpha_deg = ( math.acos( (h0 - delta_h)/R_m ) - theta0_rad )*R2D;
# Outputs
instrumentLightFactor.setDoubleValue(instrumentsNorm.getValue());
panelLights.setDoubleValue(instrumentsNorm.getValue());
filteredCDI0.setDoubleValue( cdi0_lowpass.filter(cdiNAV0.getValue()));
filteredCDI1.setDoubleValue(cdi1_lowpass.filter(cdiNAV1.getValue()));
filteredGS0.setDoubleValue(gs0_lowpass.filter(gsNAV0.getValue()));
filteredGS1.setDoubleValue(gs1_lowpass.filter(gsNAV1.getValue()));
nose_link_rot.setDoubleValue(theta);
right_main_rot.setDoubleValue(right_alpha_deg);
left_main_rot.setDoubleValue(left_alpha_deg);
settimer(update_actions, 0);
}
var scissor_angle = func(H,C,L,phi) {
var a = (H - C)/2/L;
# Use 2 iterates of Newton's method and 4th order Taylor series to
# approximate theta where sin(phi - theta) = a
var theta = phi - 2*a/3 - a/3/(1-a*a/2);
return theta;
}
# Setup listener call to start update loop once the fdm is initialized
#
setlistener("sim/signals/fdm-initialized", init_actions);