Air pressure height impl

app/src/main/java/src/land/LandingController.java

@@ -16,6 +16,11 @@ public class LandingController
 	private final double AIR_DENSITY = 5.428; 		// https://www.aero.psu.edu/avia/pubs/LanSch17.pdf, page 3
 	private final double LANDER_AREA = 1.91; 		// Mars InSight lander was 1.56 meters in diameter, pi * radius^2
 	private final double PARACHUTE_AREA = 1000;
+	private final double airPresSeaLevel = 1.5;		// 1.5 bars
+	private final double grav = 1.352;				// acceleration due to gravity
+	private final double k = 1.38064852e-23;		// Boltzmann constants
+	private final double m = 27.60867588;			// average molar mass of air molecules
+
 
 	protected boolean parachuteDeployed = false;
 
@@ -50,8 +55,9 @@ public ArrayList<LanderObject> plotTrajectory(Vector3d landerLocation,
 		{
 			Logger.logCSV("landing_controller", time + "," + currentState.position.get(0).toCSV() + currentState.velocity.get(0).toCSV());
 
-			//Vector3d drag = calculateDrag(currentState.velocity.get(0));
-			//currentState.velocity.set(0, currentState.velocity.get(0).add(drag));
+			Vector3d drag = calculateDrag(currentState.velocity.get(0),currentState.position.get(0));
+			currentState.velocity.set(0, currentState.velocity.get(0).add(drag));
+
 
 			currentState = solver.step(f, time, currentState, stepSize);
 			trajectory.add(new LanderObject(currentState.position.get(0), 0));
@@ -101,7 +107,7 @@ public Vector3d removeZDimension(Vector3d v)
 	 * Implementing Fd = Cd * rho * V^2 * Area * 1/2 * unitVector
 	 * Represents (respectively): Force of drag = dragCoefficient * airDensity * magnitudeOfVelocity^2 * 1/2 * unitVector  
 	 */
-	public Vector3d calculateDrag(Vector3d velocity)
+	public Vector3d calculateDrag(Vector3d velocity, Vector3d position)
 	{
 		if (velocity.getX() == 0 && velocity.getY() == 0) {
 			return new Vector3d(0,0,0);
@@ -114,7 +120,7 @@ public Vector3d calculateDrag(Vector3d velocity)
 		if(parachuteDeployed)
 			totalArea = totalArea + PARACHUTE_AREA;
 
-		double constant = DRAG_COEFFICIENT * totalArea * AIR_DENSITY * veloMagnitude * veloMagnitude * 0.5;
+		double constant = DRAG_COEFFICIENT * LANDER_AREA * airPresSeaLevel * veloMagnitude * veloMagnitude * 0.5;
 
 		Vector3d dragForce = vectorDirection.mul(constant);					//scale the unit vector by the constants we have, to get the actual drag force vector	
 		return dragForce;
@@ -136,4 +142,48 @@ protected void deployParachute()
 	{
 		parachuteDeployed = true;
 	}
+
+	/*
+	 * Method represents:
+	 * Ph = P0 * e^((-m*g*h)/k*T
+	 * Where:
+	 * Ph is pressure at height, P0 pressure at seal level
+	 * m is mass of one molecule of..., g is gravitational acceleration, h is the height	
+	 * k is Boltzmann's constant, t is the absolute temperature (in kelvin)
+	 * 
+	 * 
+	 * if impact() is true, return 1.5 (on surface)
+	 */
+	public double airPressureAt(Vector3d height) {
+
+		double h = height.dist(new Vector3d());
+		double t = generateTemp(h);
+
+		double result = airPresSeaLevel * Math.exp((-m*grav*h)/k*t);
+		return result;
+	}
+
+	public double generateTemp(double height) {
+		if (height == 0) {							// if impacted on surface hence temp is given
+			return 94;
+		}
+		else if (0<height && height<50000) {
+			long min = (long) 71;
+			long max = (long) 81;
+			double randValue = (double)Math.floor(Math.random()*(max-min+1)+min);
+			return randValue;
+		}
+		else if (height>=50000 && height<200000) {
+			long min = (long) 71;
+			long max = (long) 180;
+			double randValue = (double)Math.floor(Math.random()*(max-min+1)+min);
+			return randValue;
+		}
+		else {
+			long min = (long) 160;
+			long max = (long) 180;
+			double randValue = (double)Math.floor(Math.random()*(max-min+1)+min);
+			return randValue;
+		}
+	}
 }

app/src/test/java/src/test/TestLandingController.java

@@ -24,6 +24,27 @@ void logFallFromOrbit()
 		double titanRadius = 2575.5e3;
 	}
 
+	@Test
+	void logBallFallFromOrbit() 
+	{
+		LandingController lc = new LandingController();
+
+		Vector3d landerPos = new Vector3d(0,20000,100);
+		Vector3d landerVel = new Vector3d(0,0,0);
+		double landerMass = 1000;
+		Vector3d titanPos = new Vector3d(0,0,0);
+		Vector3d titanVel = new Vector3d(0,0,0);
+		double titanMass = 1e16;
+		double titanRadius = 100;
+
+		Vector3d[] array = lc.plotTrajectory(landerPos, landerVel, landerMass, titanPos, titanVel, titanMass, titanRadius);
+		for(int i = 0;i<array.length;i++)
+		{
+			System.out.println(array[i]);
+		}
+	}
+
+
 	/**
 	 * 	Testing Strategy:
 	 *  	|  1 |  2 |  3 |  4 |  5 |  6 |  7 |  8 |  9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 |
@@ -158,7 +179,8 @@ void logFallFromOrbit()
 	{
 		LandingController controller = new LandingController();
 		Vector3d velocity = new Vector3d(5,10,0);
-		Vector3d drag = controller.calculateDrag(velocity);
+		Vector3d position = new Vector3d();
+		Vector3d drag = controller.calculateDrag(velocity,position);
 		Vector3d expectedDrag = new Vector3d(-608.5377,-1217.0754,-0);
 		assertEquals(expectedDrag.getX(),drag.getX(),0.01);
 		assertEquals(expectedDrag.getY(),drag.getY(),0.01);
@@ -177,7 +199,8 @@ void logFallFromOrbit()
 	{
 		LandingController controller = new LandingController();
 		Vector3d velocity = new Vector3d(-5,-10,0);
-		Vector3d drag = controller.calculateDrag(velocity);
+		Vector3d position = new Vector3d();
+		Vector3d drag = controller.calculateDrag(velocity,position);
 		Vector3d expectedDrag = new Vector3d(608.5377,1217.0754,0);
 		System.out.println(drag.getX());
 		System.out.println(drag.getY());
@@ -198,7 +221,8 @@ void logFallFromOrbit()
 	{
 		LandingController controller = new LandingController();
 		Vector3d velocity = new Vector3d(0,0,0);
-		Vector3d drag = controller.calculateDrag(velocity);
+		Vector3d position = new Vector3d();
+		Vector3d drag = controller.calculateDrag(velocity,position);
 		Vector3d expectedDrag = new Vector3d(0,0,0);
 		assertEquals(expectedDrag.getX(),drag.getX());
 		assertEquals(expectedDrag.getY(),drag.getY());
@@ -231,6 +255,10 @@ void logFallFromOrbit()
 		assertEquals(control.normalise(new Vector3d(100,94,45),new Vector3d(213,432,113)),new Vector3d(-113,-338,-68));
 	}
 
-
+	@Test void testPressureAt() {
+		LandingController control = new LandingController();
+		Vector3d position = new Vector3d(0,2e25,0);
+		System.out.println(control.airPressureAt(position));
+	}
 
 }

app/src/test/java/src/test/TestOpenLoopController.java

@@ -1,5 +1,7 @@
 package src.test;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
 import org.junit.jupiter.api.Test;
 
 import src.land.LandingController;
@@ -8,6 +10,101 @@
 
 public class TestOpenLoopController {
 
+	/*
+	 * REP. INV.:
+	 * Height should be > radius
+	 * 
+	 * PARTITIONS:						Above				  |	Below
+	 * Left-hand side of planet			point = -ve,0 > height|	point = -ve,0 < height
+	 * Right-hand side of planet		point = +ve,0 > height|	point = +ve,0 < height
+	 * Centre above planet				point = 0,+ve > height| point = 0,+ve < height
+	 * Centre below planet				point = 0,-ve > height|	point = 0,-ve < height
+	 * 
+	 * Special cases:
+	 * Height of point == height, --> false
+	 * Height of point, impact() is true, --> true
+	 */
+
+	@Test 
+	void testAboveHeightRHSide() {
+
+		OpenLoopController controller = new OpenLoopController();
+		Vector3d point = new Vector3d(50000,0,0);
+		assertEquals(!controller.belowHeight(point),true);
+	}
+
+	@Test 
+	void testAboveHeightLHSide() {
+
+		OpenLoopController controller = new OpenLoopController();
+		Vector3d point = new Vector3d(-50000,0,0);
+		assertEquals(!controller.belowHeight(point),true);
+	}
+
+	@Test 
+	void testAboveHeightCentreTop() {
+
+		OpenLoopController controller = new OpenLoopController();
+		Vector3d point = new Vector3d(0,60000,0);
+		assertEquals(!controller.belowHeight(point),true);
+	}
+
+	@Test 
+	void testAboveHeightCentreBottom() {
+
+		OpenLoopController controller = new OpenLoopController();
+		Vector3d point = new Vector3d(0,-60000,0);
+		assertEquals(!controller.belowHeight(point),true);
+	}
+
+	@Test 
+	void testBelowHeightRHSide() {
+
+		OpenLoopController controller = new OpenLoopController();
+		Vector3d point = new Vector3d(5000,0,0);
+		assertEquals(controller.belowHeight(point),true);
+	}
+
+	@Test 
+	void testBelowHeightLHSide() {
+
+		OpenLoopController controller = new OpenLoopController();
+		Vector3d point = new Vector3d(-5000,0,0);
+		assertEquals(controller.belowHeight(point),true);
+	}
+
+	@Test 
+	void testBelowHeightCentreTop() {
+
+		OpenLoopController controller = new OpenLoopController();
+		Vector3d point = new Vector3d(0,6000,0);
+		assertEquals(controller.belowHeight(point),true);
+	}
+
+	@Test 
+	void testBelowHeightCentreBottom() {
+
+		OpenLoopController controller = new OpenLoopController();
+		Vector3d point = new Vector3d(0,-6000,0);
+		assertEquals(controller.belowHeight(point),true);
+	}
+
+	@Test
+	void testHeightsEqual() {
+
+		OpenLoopController controller = new OpenLoopController();
+		Vector3d point = new Vector3d(0,40000,0);
+		assertEquals(!controller.belowHeight(point),true);
+	}
+
+	@Test
+	void testImpactTrue() {
+
+		OpenLoopController controller = new OpenLoopController();
+		Vector3d point = new Vector3d(100,100,0);
+		assertEquals(controller.belowHeight(point),true);
+	}
+
 	@Test
 	void logFallFromOrbit() 
 	{