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Move actual Euler integration into a separate method, to avoid code duplication when it has to be recalculated.

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This commit is contained in:
JoePfeiffer 2024-02-25 09:21:34 -07:00
parent b285de1c49
commit e6e92d6a7b
1 changed files with 25 additions and 9 deletions
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34
core/src/net/sf/openrocket/simulation/AbstractEulerStepper.java
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@ -91,11 +91,13 @@ public abstract class AbstractEulerStepper extends AbstractSimulationStepper {
log.trace("timeStep is " + timeStep);
// Perform Euler integration
EulerValues newVals = eulerIntegrate(status.getRocketPosition(), status.getRocketVelocity(), linearAcceleration, timeStep);
/*
Coordinate newPosition = status.getRocketPosition().add(status.getRocketVelocity().multiply(timeStep)).
add(linearAcceleration.multiply(MathUtil.pow2(timeStep) / 2));
add(linearAcceleration.multiply(MathUtil.pow2(timeStep) / 2));*/
// If I've hit the ground, recalculate time step and position
if (newPosition.z < 0) {
if (newVals.pos.z < 0) {
final double a = linearAcceleration.z;
final double v = status.getRocketVelocity().z;
@ -105,19 +107,18 @@ public abstract class AbstractEulerStepper extends AbstractSimulationStepper {
// 1/2 at^2 + vt + z0 = 0
timeStep = (-v - Math.sqrt(v*v - 2*a*z0))/a;
log.trace("ground hit changes timeStep to " + timeStep);
newPosition = status.getRocketPosition().add(status.getRocketVelocity().multiply(timeStep)).
add(linearAcceleration.multiply(MathUtil.pow2(timeStep) / 2));
newVals = eulerIntegrate(status.getRocketPosition(), status.getRocketVelocity(), linearAcceleration, timeStep);
// avoid rounding error in new altitude
newPosition = newPosition.setZ(0);
newVals.pos = newVals.pos.setZ(0);
}
status.setSimulationTime(status.getSimulationTime() + timeStep);
status.setPreviousTimeStep(timeStep);
status.setRocketPosition(newPosition);
status.setRocketVelocity(status.getRocketVelocity().add(linearAcceleration.multiply(timeStep)));
status.setRocketPosition(newVals.pos);
status.setRocketVelocity(newVals.vel);
status.setRocketAcceleration(linearAcceleration);
// Update the world coordinate
@ -190,5 +191,20 @@ public abstract class AbstractEulerStepper extends AbstractSimulationStepper {
(System.nanoTime() - status.getSimulationStartWallTime()) / 1000000000.0);
log.trace("time " + data.getLast(FlightDataType.TYPE_TIME) + ", altitude " + data.getLast(FlightDataType.TYPE_ALTITUDE) + ", velocity " + data.getLast(FlightDataType.TYPE_VELOCITY_Z));
}
private static class EulerValues {
/** linear velocity */
public Coordinate vel;
/** position */
public Coordinate pos;
}
private EulerValues eulerIntegrate (Coordinate pos, Coordinate v, Coordinate a, double timeStep) {
EulerValues result = new EulerValues();
result.vel = v.add(a.multiply(timeStep));
result.pos = pos.add(v.multiply(timeStep)).add(a.multiply(MathUtil.pow2(timeStep) / 2.0));
return result;
}
}