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Implement drag #111

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merged 3 commits into from
Jun 21, 2021
Merged

Implement drag #111

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ff50fe6
implements parachute system
S010MON Jun 20, 2021
b67fde2
Implement addition of drag per iteration
S010MON Jun 20, 2021
a06e8e3
Temp comment out drag
S010MON Jun 21, 2021
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20 changes: 18 additions & 2 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 @@ -12,9 +12,12 @@

public class LandingController
{
private final double LANDER_AREA = 1.91; // Mars InSight lander was 1.56 meters in diameter, pi * radius^2
private final double DRAG_COEFFICIENT = 2.1; // page 1187, from https://pdfs.semanticscholar.org/5410/30f5b4c387a3d5d06fbee8549347d6bddf82.pdf
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;

protected boolean parachuteDeployed = false;

public LandingController()
{
Expand Down Expand Up @@ -51,6 +54,10 @@ public Vector3d[] plotTrajectory(Vector3d landerLocation,
while(!impact(currentState.position.get(0), currentState.position.get(1), planetRadius))
{
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));

currentState = solver.step(f, time, currentState, stepSize);
trajectory.add(currentState.position.get(0));
time = time + stepSize;
Expand Down Expand Up @@ -108,7 +115,11 @@ public Vector3d calculateDrag(Vector3d velocity)
Vector3d vectorDirection = unitVector.mul(-1); //drag acts in the opposite direction in relation to the velocity.

double veloMagnitude = velocity.norm();
double constant = DRAG_COEFFICIENT * LANDER_AREA * AIR_DENSITY * veloMagnitude * veloMagnitude * 0.5;
double totalArea = LANDER_AREA;
if(parachuteDeployed)
totalArea = totalArea + PARACHUTE_AREA;

double constant = DRAG_COEFFICIENT * totalArea * AIR_DENSITY * 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;
Expand All @@ -125,4 +136,9 @@ protected Vector3d[] toArray(ArrayList<Vector3d> input)
}
return array;
}

protected void deployParachute()
{
parachuteDeployed = true;
}
}