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Merge pull request #1947 from JoePfeiffer/tumble-solve-for-0

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Solve time step for ground hit in tumble stepper
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Joe Pfeiffer 2023-01-05 10:55:58 -07:00 committed by GitHub
commit 4010fe3f5b
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1 changed files with 21 additions and 0 deletions
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core/src/net/sf/openrocket/simulation/BasicTumbleStepper.java
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@ -69,6 +69,27 @@ public class BasicTumbleStepper extends AbstractSimulationStepper {
double timeStep = MathUtil.min(0.5 / linearAcceleration.length(), RECOVERY_TIME_STEP);
// Perform Euler integration
Coordinate newPosition = status.getRocketPosition().add(status.getRocketVelocity().multiply(timeStep)).
add(linearAcceleration.multiply(MathUtil.pow2(timeStep) / 2));
// If I've hit the ground, recalculate time step and position
if (newPosition.z < 0) {
final double a = linearAcceleration.z;
final double v = status.getRocketVelocity().z;
final double z0 = status.getRocketPosition().z;
// The new timestep is the solution of
// 1/2 at^2 + vt + z0 = 0
timeStep = (-v - Math.sqrt(v*v - 2*a*z0))/a;
newPosition = status.getRocketPosition().add(status.getRocketVelocity().multiply(timeStep)).
add(linearAcceleration.multiply(MathUtil.pow2(timeStep) / 2));
// avoid rounding error in new altitude
newPosition = newPosition.setZ(0);
}
status.setRocketPosition(status.getRocketPosition().add(status.getRocketVelocity().multiply(timeStep)).
add(linearAcceleration.multiply(MathUtil.pow2(timeStep) / 2)));
status.setRocketVelocity(status.getRocketVelocity().add(linearAcceleration.multiply(timeStep)));