From fe302e0a3dc01b770181f500c425337fcd4036e5 Mon Sep 17 00:00:00 2001
From: Marcodagostino2 <mcdago25@gmail.com>
Date: Sat, 16 Nov 2024 14:30:38 +0100
Subject: [PATCH] [design-updates] Fixed model gravity. Gravity model use a
point-mass gravitation model with an Earth radius defined in the Environment
class.
---
classes/components/Environment.m | 62 +++++++++---------------------
functions/odeFunctions/ballistic.m | 6 +--
2 files changed, 20 insertions(+), 48 deletions(-)
diff --git a/classes/components/Environment.m b/classes/components/Environment.m
index c0c5cd9..52ba0b1 100644
--- a/classes/components/Environment.m
+++ b/classes/components/Environment.m
@@ -12,29 +12,28 @@ classdef Environment < Component
% file
properties
- lat0 double % [deg] Launchpad latitude
- lon0 double % [deg] Launchpad longitude
- z0 double % [m] Launchpad Altitude
- omega double % [deg] Launchpad Elevation
- phi double % [deg] Launchpad Azimuth
- pin1Length double % [m] Distance from the upper pin to the upper tank cap
- pin2Length double % [m] Distance from the lower pin to the lower tank cap
- rampLength double % [m] Total launchpad length
+ lat0 double % [deg] Launchpad latitude
+ lon0 double % [deg] Launchpad longitude
+ z0 double % [m] Launchpad Altitude
+ omega double % [deg] Launchpad Elevation
+ phi double % [deg] Launchpad Azimuth
+ pin1Length double % [m] Distance from the upper pin to the upper tank cap
+ pin2Length double % [m] Distance from the lower pin to the lower tank cap
+ rampLength double % [m] Total launchpad length
- temperature double = 288.15 % [K] Ground temperature
- pressure double % [Pa] Ground pressure
- rho double % [Kg/m^3] Ground air density
- gamma double = 1.4 % [-] Gas constant
+ temperature double = 288.15 % [K] Ground temperature
+ pressure double % [Pa] Ground pressure
+ rho double % [Kg/m^3] Ground air density
+ gamma double = 1.4 % [-] Gas constant
end
properties(SetAccess = private)
- g0 double % [-] Gravity costant at launch latitude and z = 0m
- g0Centrifugal double % [m/s^2] Gravity due to earth rotation at launch latitude and z = 0m
- earthRadius double % [m] Radius used for g computation
- local double % [-] Vector conatining inputs for atmosphereData
- pinDistance double % [m] Distance of the upper pin from the rail base (upper pin-boat + boat-rail base)
- effectiveRampLength double % [m] Total launchpad length
- effectiveRampAltitude double % [m] Projection of effectiveRampLength on z axis
+ g0 double % [-] Gravity costant at launch latitude and altitude
+ earthRadius double = 6371007 % [m] Radius used for g computation
+ local double % [-] Vector conatining inputs for atmosphereData
+ pinDistance double % [m] Distance of the upper pin from the rail base (upper pin-boat + boat-rail base)
+ effectiveRampLength double % [m] Total launchpad length
+ effectiveRampAltitude double % [m] Projection of effectiveRampLength on z axis
end
properties(Access = protected)
@@ -66,8 +65,6 @@ classdef Environment < Component
methods
function updateAll(obj)
obj.updateG0;
- obj.updateG0Centrifugal;
- obj.updateEarthRadius;
obj.updatePinDistance;
obj.updateRamp;
obj.updateLocal;
@@ -81,28 +78,7 @@ classdef Environment < Component
function obj = updateG0(obj)
if(~isempty(obj.lat0))
- obj.g0 = gravitywgs84(0, obj.lat0);
- end
- end
-
- function obj = updateG0Centrifugal(obj)
- if(~isempty(obj.lat0))
- earthOmega = 2*pi/86164; % [rad/s] Earth angular velocity
- aEarth = 6378122; % [m] Earth semi major axis (radius at the equator)
- eEarth = 0.08182; % [/] Earth's ellipsoid eccentricity
- lat0rad = deg2rad(obj.lat0);
- obj.g0Centrifugal = - earthOmega^2 * aEarth * ((cos(lat0rad)^2)/(sqrt(1 - eEarth^2*(sin(lat0rad)^2))));
- end
- end
-
- function obj = updateEarthRadius(obj)
- if(~isempty(obj.lat0))
- earthOmega = 2*pi/86164;
- R0 = 6370000;
- lat0rad = deg2rad(obj.lat0);
- mu = 3.986e14; % [m^3/s^2] Earth's gravitational constant (GM)
- f = @(R) obj.g0 - (mu/(R^2)) + earthOmega^2*R*(cos(lat0rad)^2);
- obj.earthRadius = fzero(f, R0);
+ obj.g0 = gravitywgs84(obj.z0, obj.lat0);
end
end
diff --git a/functions/odeFunctions/ballistic.m b/functions/odeFunctions/ballistic.m
index 391f3c3..cce9648 100644
--- a/functions/odeFunctions/ballistic.m
+++ b/functions/odeFunctions/ballistic.m
@@ -58,11 +58,7 @@ dY = zeros(14, 1);
%% GETTING DATA
S = rocket.crossSection; % [m^2] cross surface
C = rocket.diameter; % [m] caliber
-earthOmega = 2*pi/86164; % [rad/s] Earth's angular velocity
-g = (environment.g0 - environment.g0Centrifugal)/...
- ((1 + ((altitude + environment.z0)/environment.earthRadius))^2) + ...
- environment.g0Centrifugal - earthOmega^2*...
- (altitude + environment.z0)*(cos(environment.lat0*pi/180)^2); % [N/kg] module of gravitational field
+g = environment.g0/(1 + (altitude/environment.earthRadius))^2; % [N/kg] module of gravitational field
tb = rocket.motor.cutoffTime; % [s] Burning Time
theta = t-t0; % [s] Time shift (needed for control)
local = environment.local; % vector containing inputs for atmosphereData
--
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