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Varying air pressure fixed #117

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merged 4 commits into from
Jun 21, 2021
Merged

Varying air pressure fixed #117

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97ba851
Fixed implementation issue with air pressure scaling.
Jun 21, 2021
d50b7c7
Fixed implementation of air pressure scaling.
Jun 21, 2021
57a012c
Fixed implementation of air pressure scaling in controller, open&landing
Cagancancacan Jun 21, 2021
e270993
Added 2 more partitions to air pressure scaling tests.
Cagancancacan Jun 21, 2021
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16 changes: 8 additions & 8 deletions app/src/main/java/src/land/LandingController.java
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Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand All @@ -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);

Expand Down Expand Up @@ -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);
Expand All @@ -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();
Expand Down Expand Up @@ -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;
}
}
6 changes: 3 additions & 3 deletions app/src/main/java/src/land/OpenLoopController.java
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Expand Up @@ -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
Expand Down
36 changes: 25 additions & 11 deletions app/src/test/java/src/test/TestLandingController.java
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Expand Up @@ -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
Expand All @@ -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());
Expand All @@ -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());
Expand Down Expand Up @@ -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();
Expand All @@ -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));
}
}