Merge pull request #117 from group22DKE/varying_resistance_fix

Varying air pressure fixed

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

@@ -20,15 +20,15 @@ public class LandingController
 	private final double grav = 1.352;				// acceleration due to gravity
 	private final double k = 1.38064852e-23;		// Boltzmann constants
 	private final double m = 27.60867588e-3;		// average molar mass of air molecules
-
+	 
 	protected double stepSize = 1;
 	protected double deployParachuteHeight = 5000;
 	protected int parachuteState = 0;
 	protected boolean parachuteDeployed = false;
 
 	public ArrayList<LanderObject> plotTrajectory(Vector3d landerLocation, 
 			 						 Vector3d landerVelocity,
-									 double landerMass,
+									 double landerMass, 
 									 Vector3d planetLocation,
 									 Vector3d planetVelocity,
 									 double planetMass,
@@ -50,14 +50,14 @@ public ArrayList<LanderObject> plotTrajectory(Vector3d landerLocation,
 
 		ArrayList<LanderObject> trajectory = new ArrayList<LanderObject>();
 
-		Logger.logCSV("landing_controller", "Time,Pos X, Pos Y, Pos Z, Vel X, Vel Y, Vel Z");
+		Logger.logCSV("landing_controller3", "Time,Pos X, Pos Y, Pos Z, Vel X, Vel Y, Vel Z");
 
 		double time = 0;
 		while(!testHeight(currentState.position.get(0), currentState.position.get(1), planetRadius))
 		{
-			Logger.logCSV("landing_controller", time + "," + currentState.position.get(0).toCSV() + currentState.velocity.get(0).toCSV());
+			Logger.logCSV("landing_controller3", time + "," + currentState.position.get(0).toCSV() + currentState.velocity.get(0).toCSV());
 
-			Vector3d drag = calculateDrag(currentState.velocity.get(0), currentState.position.get(0), stepSize);
+			Vector3d drag = calculateDrag(currentState.velocity.get(0), currentState.position.get(0), stepSize, planetRadius);
 			currentState.velocity.set(0, currentState.velocity.get(0).sub(drag));
 			currentState = solver.step(f, time, currentState, stepSize);
 
@@ -111,7 +111,7 @@ public Vector3d removeZDimension(Vector3d v)
 	 * Implementing Fd = Cd * rho * (V^2 * Area)/2 * unitVector
 	 * Represents (respectively): Force of drag = dragCoefficient * airDensity * magnitudeOfVelocity^2 * 1/2 * unitVector  
 	 */
-	public Vector3d calculateDrag(Vector3d velocity, Vector3d position, double stepSize)
+	public Vector3d calculateDrag(Vector3d velocity, Vector3d position, double stepSize, double radius)
 	{
 		if (velocity.getX() == 0 && velocity.getY() == 0)
 			return new Vector3d(0,0,0);
@@ -121,7 +121,7 @@ public Vector3d calculateDrag(Vector3d velocity, Vector3d position, double stepS
 			totalArea = totalArea + getParachuteState();
 
 		double veloMagnitude = velocity.norm();
-		double drag = DRAG_COEFFICIENT * airPresSeaLevel * ((totalArea * (veloMagnitude * veloMagnitude))/2);
+		double drag = DRAG_COEFFICIENT * airPressureScaling(position, radius) * ((totalArea * (veloMagnitude * veloMagnitude))/2);
 		drag = drag * stepSize;
 
 		Vector3d direction = velocity.unitVector();
@@ -212,7 +212,7 @@ else if (-radius<realDistance && realDistance<=0) {			//touching or inside the p
 			return airPresSeaLevel;
 		}
 
-		double scaleOfDistance = realDistance/atmosphereMaxRange;
+		double scaleOfDistance = 1-(realDistance/atmosphereMaxRange);
 		return scaleOfDistance*airPresSeaLevel;
 	}
 }

app/src/main/java/src/land/OpenLoopController.java

@@ -52,11 +52,11 @@ public ArrayList<LanderObject> plotTrajectory(Vector3d landerLocation,
 			if(!parachuteDeployed && testHeight(currentState.position.get(0), currentState.position.get(1), planetRadius + deployParachuteHeight))
 				deployParachute();
 
-			Vector3d drag = calculateDrag(currentState.velocity.get(0), currentState.position.get(0), stepSize);
+			Vector3d drag = calculateDrag(currentState.velocity.get(0), currentState.position.get(0), stepSize, planetRadius);
 			currentState.velocity.set(0, currentState.velocity.get(0).sub(drag));
 			currentState = solver.step(f, time, currentState, stepSize);
-
-			trajectory.add(new LanderObject(currentState.position.get(0), 0));
+			 
+			trajectory.add(new LanderObject(currentState.position.get(0), 0)); 
 			time = time + stepSize;
 
 			if(time > 1e7)// Safety cutoff

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

@@ -177,13 +177,13 @@ void logBallFallFromOrbit()
 	{
 		LandingController controller = new LandingController();
 		Vector3d velocity = new Vector3d(5,10,0);
-		Vector3d position = new Vector3d();
-		Vector3d drag = controller.calculateDrag(velocity,position, 1);
+		Vector3d position = new Vector3d(); 
+		Vector3d drag = controller.calculateDrag(velocity,position, 1, 1);			//placeholder radius value
 		Vector3d expectedDrag = new Vector3d(-608.5377,-1217.0754,-0);
 		assertEquals(expectedDrag.getX(),drag.getX(),0.01);
 		assertEquals(expectedDrag.getY(),drag.getY(),0.01);
 		assertEquals(expectedDrag.getZ(),drag.getZ(),0.01);
-	}
+	} 
 
 	/**
 	 * Tests drag for negative velocity
@@ -198,7 +198,7 @@ void logBallFallFromOrbit()
 		LandingController controller = new LandingController();
 		Vector3d velocity = new Vector3d(-5,-10,0);
 		Vector3d position = new Vector3d();
-		Vector3d drag = controller.calculateDrag(velocity,position, 1);
+		Vector3d drag = controller.calculateDrag(velocity,position, 1, 1);
 		Vector3d expectedDrag = new Vector3d(608.5377,1217.0754,0);
 		System.out.println(drag.getX());
 		System.out.println(drag.getY());
@@ -220,7 +220,7 @@ void logBallFallFromOrbit()
 		LandingController controller = new LandingController();
 		Vector3d velocity = new Vector3d(0,0,0);
 		Vector3d position = new Vector3d();
-		Vector3d drag = controller.calculateDrag(velocity,position, 1);
+		Vector3d drag = controller.calculateDrag(velocity,position, 1, 1);
 		Vector3d expectedDrag = new Vector3d(0,0,0);
 		assertEquals(expectedDrag.getX(),drag.getX());
 		assertEquals(expectedDrag.getY(),drag.getY());
@@ -261,11 +261,13 @@ void logBallFallFromOrbit()
 
 
 	/*
-	 * Partitions:
-	 * Out of the atmosphere's range
-	 * In the atmoshpere's range
-	 * Touching the radius
-	 * On/inside the planet 
+	 * PARTITIONS:
+	 * 	Out of the atmosphere's range
+	 * 	In the atmoshpere's range
+	 * 	Touching the radius
+	 * 	On/inside the planet 
+	 * 	Just above halfway
+	 * 	Just below halfway
 	 */
 	@Test void testAirPresScalingAboveMax() {
 		LandingController control = new LandingController();
@@ -285,9 +287,21 @@ void logBallFallFromOrbit()
 		System.out.println(control.airPressureScaling(position,10));
 	}
 
-	@Test void testAirPresScalingHalfway() {
+	@Test void testAirPresScalingHalfway() {								//should be 0.75
 		LandingController control = new LandingController();
 		Vector3d position = new Vector3d(0,500000,0);
 		System.out.println(control.airPressureScaling(position,200000));
 	}
+
+	@Test void testAirPresScalingHalfOffsetUp() {								//should be less than 0.75
+		LandingController control = new LandingController();
+		Vector3d position = new Vector3d(0,550000,0);
+		System.out.println(control.airPressureScaling(position,200000));
+	}
+
+	@Test void testAirPresScalingHalfOffsetDown() {								//should be more than 0.75
+		LandingController control = new LandingController();
+		Vector3d position = new Vector3d(0,450000,0);
+		System.out.println(control.airPressureScaling(position,200000));
+	}
 }