Merge pull request #2514 from JoePfeiffer/fix-2443
Reduce redundant acceleration data storage
This commit is contained in:
Sibo Van Gool
GitHub
commit
3f8a118298
@ -70,22 +70,24 @@ public abstract class AbstractEulerStepper extends AbstractSimulationStepper {
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}
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// Compute drag acceleration
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store.linearAcceleration = airSpeed.normalize().multiply(-store.dragForce / store.rocketMass.getMass());
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Coordinate linearAcceleration = airSpeed.normalize().multiply(-store.dragForce / store.rocketMass.getMass());
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// Add effect of gravity
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store.gravity = modelGravity(status);
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store.linearAcceleration = store.linearAcceleration.sub(0, 0, store.gravity);
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linearAcceleration = linearAcceleration.sub(0, 0, store.gravity);
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// Add coriolis acceleration
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store.coriolisAcceleration = status.getSimulationConditions().getGeodeticComputation().getCoriolisAcceleration(
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status.getRocketWorldPosition(), status.getRocketVelocity());
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store.linearAcceleration = store.linearAcceleration.add(store.coriolisAcceleration);
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linearAcceleration = linearAcceleration.add(store.coriolisAcceleration);
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store.accelerationData = new AccelerationData(null, null, linearAcceleration, Coordinate.NUL, status.getRocketOrientationQuaternion());
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// Select tentative time step
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store.timeStep = RECOVERY_TIME_STEP;
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// adjust based on acceleration
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final double absAccel = store.linearAcceleration.length();
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final double absAccel = linearAcceleration.length();
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if (absAccel > MathUtil.EPSILON) {
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store.timeStep = Math.min(store.timeStep, 1.0/absAccel);
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}
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@ -105,7 +107,7 @@ public abstract class AbstractEulerStepper extends AbstractSimulationStepper {
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log.trace("timeStep is " + store.timeStep);
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// Perform Euler integration
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EulerValues newVals = eulerIntegrate(status.getRocketPosition(), status.getRocketVelocity(), store.linearAcceleration, store.timeStep);
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EulerValues newVals = eulerIntegrate(status.getRocketPosition(), status.getRocketVelocity(), linearAcceleration, store.timeStep);
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// Check to see if z or either of its first two derivatives have changed sign and recalculate
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// time step to point of change if so
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@ -115,7 +117,7 @@ public abstract class AbstractEulerStepper extends AbstractSimulationStepper {
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// Note that it's virtually impossible for apogee to occur on the same
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// step as either ground hit or descent rate inflection, and if we get a ground hit
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// any descent rate inflection won't matter
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final double a = store.linearAcceleration.z;
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final double a = linearAcceleration.z;
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final double v = status.getRocketVelocity().z;
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final double z = status.getRocketPosition().z;
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double t = store.timeStep;
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@ -136,11 +138,11 @@ public abstract class AbstractEulerStepper extends AbstractSimulationStepper {
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// dA/dT = dA/dV * dV/dT
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final double dFdV = CdA * store.atmosphericConditions.getDensity() * airSpeed.length();
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final Coordinate dAdV = airSpeed.normalize().multiply(dFdV / store.rocketMass.getMass());
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final Coordinate jerk = store.linearAcceleration.multiply(dAdV);
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final Coordinate newAcceleration = store.linearAcceleration.add(jerk.multiply(store.timeStep));
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final Coordinate jerk = linearAcceleration.multiply(dAdV);
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final Coordinate newAcceleration = linearAcceleration.add(jerk.multiply(store.timeStep));
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// Only do this one if acceleration is appreciably different from 0
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if (newAcceleration.z * store.linearAcceleration.z < -MathUtil.EPSILON) {
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if (newAcceleration.z * linearAcceleration.z < -MathUtil.EPSILON) {
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// If acceleration oscillation is building up, the new timestep is the solution of
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// a + j*t = 0
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t = Math.abs(a / jerk.z);
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@ -159,7 +161,7 @@ public abstract class AbstractEulerStepper extends AbstractSimulationStepper {
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store.timeStep = maxTimeStep;
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}
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newVals = eulerIntegrate(status.getRocketPosition(), status.getRocketVelocity(), store.linearAcceleration, store.timeStep);
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newVals = eulerIntegrate(status.getRocketPosition(), status.getRocketVelocity(), linearAcceleration, store.timeStep);
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// If we just landed chop off rounding error
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if (Math.abs(newVals.pos.z) < MathUtil.EPSILON) {
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@ -171,7 +173,6 @@ public abstract class AbstractEulerStepper extends AbstractSimulationStepper {
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status.setRocketPosition(newVals.pos);
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status.setRocketVelocity(newVals.vel);
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status.setRocketAcceleration(store.linearAcceleration);
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// Update the world coordinate
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WorldCoordinate w = status.getSimulationConditions().getLaunchSite();
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@ -163,14 +163,12 @@ public abstract class AbstractSimulationStepper implements SimulationStepper {
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*
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* @param status the current simulation status.
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* @param timestep the time step of the current iteration.
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* @param acceleration the current (approximate) acceleration
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* @param atmosphericConditions the current atmospheric conditions
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* @param store the simulation calculation DataStore (contains acceleration, atmosphere)
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* @param stepMotors whether to step the motors forward or work on a clone object
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* @return the average thrust during the time step.
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*/
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protected double calculateThrust(SimulationStatus status,
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double acceleration, AtmosphericConditions atmosphericConditions,
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boolean stepMotors) throws SimulationException {
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protected double calculateThrust(SimulationStatus status, DataStore store,
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boolean stepMotors) throws SimulationException {
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double thrust;
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// Pre-listeners
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@ -240,16 +238,11 @@ public abstract class AbstractSimulationStepper implements SimulationStepper {
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public FlightConditions flightConditions;
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public double longitudinalAcceleration = Double.NaN;
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public RigidBody rocketMass;
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public RigidBody motorMass;
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public Coordinate coriolisAcceleration;
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public Coordinate linearAcceleration;
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public Coordinate angularAcceleration;
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public Coordinate launchRodDirection = null;
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@ -264,9 +257,6 @@ public abstract class AbstractSimulationStepper implements SimulationStepper {
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public double dragForce = Double.NaN;
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public double lateralPitchRate = Double.NaN;
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public double rollAcceleration = Double.NaN;
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public double lateralPitchAcceleration = Double.NaN;
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public Rotation2D thetaRotation;
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void storeData(SimulationStatus status) {
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@ -286,12 +276,12 @@ public abstract class AbstractSimulationStepper implements SimulationStepper {
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dataBranch.setValue(FlightDataType.TYPE_CORIOLIS_ACCELERATION, coriolisAcceleration.length());
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}
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if (null != linearAcceleration) {
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if (null != accelerationData) {
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dataBranch.setValue(FlightDataType.TYPE_ACCELERATION_XY,
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MathUtil.hypot(linearAcceleration.x, linearAcceleration.y));
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MathUtil.hypot(accelerationData.getLinearAccelerationWC().x, accelerationData.getLinearAccelerationWC().y));
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dataBranch.setValue(FlightDataType.TYPE_ACCELERATION_TOTAL, linearAcceleration.length());
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dataBranch.setValue(FlightDataType.TYPE_ACCELERATION_Z, linearAcceleration.z);
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dataBranch.setValue(FlightDataType.TYPE_ACCELERATION_TOTAL, accelerationData.getLinearAccelerationWC().length());
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dataBranch.setValue(FlightDataType.TYPE_ACCELERATION_Z, accelerationData.getLinearAccelerationWC().z);
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}
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if (null != rocketMass) {
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@ -57,7 +57,7 @@ public class RK4SimulationStepper extends AbstractSimulationStepper {
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// private static final double MAX_ROLL_STEP_ANGLE = 8.32 * Math.PI/180;
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private static final double MAX_ROLL_RATE_CHANGE = 2 * Math.PI / 180;
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private static final double MAX_PITCH_CHANGE = 4 * Math.PI / 180;
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private static final double MAX_PITCH_YAW_CHANGE = 4 * Math.PI / 180;
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private Random random;
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DataStore store = new DataStore();
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@ -133,8 +133,10 @@ public class RK4SimulationStepper extends AbstractSimulationStepper {
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dt[1] = maxTimeStep;
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dt[2] = status.getSimulationConditions().getMaximumAngleStep() / store.lateralPitchRate;
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dt[3] = Math.abs(MAX_ROLL_STEP_ANGLE / store.flightConditions.getRollRate());
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dt[4] = Math.abs(MAX_ROLL_RATE_CHANGE / store.rollAcceleration);
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dt[5] = Math.abs(MAX_PITCH_CHANGE / store.lateralPitchAcceleration);
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dt[4] = Math.abs(MAX_ROLL_RATE_CHANGE / store.accelerationData.getRotationalAccelerationRC().z);
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dt[5] = Math.abs(MAX_PITCH_YAW_CHANGE /
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MathUtil.max(Math.abs(store.accelerationData.getRotationalAccelerationRC().x),
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Math.abs(store.accelerationData.getRotationalAccelerationRC().y)));
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if (!status.isLaunchRodCleared()) {
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dt[0] /= 5.0;
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dt[6] = status.getSimulationConditions().getLaunchRodLength() / k1.v.length() / 10;
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@ -273,8 +275,8 @@ public class RK4SimulationStepper extends AbstractSimulationStepper {
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// Call post-listeners
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store.accelerationData = SimulationListenerHelper.firePostAccelerationCalculation(status, store.accelerationData);
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params.a = dataStore.linearAcceleration;
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params.ra = dataStore.angularAcceleration;
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params.a = dataStore.accelerationData.getLinearAccelerationWC();
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params.ra = dataStore.accelerationData.getRotationalAccelerationWC();
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params.v = status.getRocketVelocity();
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params.rv = status.getRocketRotationVelocity();
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@ -298,7 +300,9 @@ public class RK4SimulationStepper extends AbstractSimulationStepper {
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* @throws SimulationException
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*/
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private AccelerationData calculateAcceleration(SimulationStatus status, DataStore store) throws SimulationException {
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Coordinate linearAcceleration;
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Coordinate angularAcceleration;
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// Compute the forces affecting the rocket
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calculateForces(status, store);
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@ -325,35 +329,33 @@ public class RK4SimulationStepper extends AbstractSimulationStepper {
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double fN = store.forces.getCN() * dynP * refArea;
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double fSide = store.forces.getCside() * dynP * refArea;
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store.thrustForce = calculateThrust(status, store.longitudinalAcceleration, store.flightConditions.getAtmosphericConditions(), false);
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store.thrustForce = calculateThrust(status, store, false);
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double forceZ = store.thrustForce - store.dragForce;
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store.linearAcceleration = new Coordinate(-fN / store.rocketMass.getMass(),
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linearAcceleration = new Coordinate(-fN / store.rocketMass.getMass(),
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-fSide / store.rocketMass.getMass(),
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forceZ / store.rocketMass.getMass());
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store.linearAcceleration = store.thetaRotation.rotateZ(store.linearAcceleration);
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linearAcceleration = store.thetaRotation.rotateZ(linearAcceleration);
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// Convert into rocket world coordinates
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store.linearAcceleration = status.getRocketOrientationQuaternion().rotate(store.linearAcceleration);
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linearAcceleration = status.getRocketOrientationQuaternion().rotate(linearAcceleration);
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// add effect of gravity
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store.gravity = modelGravity(status);
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store.linearAcceleration = store.linearAcceleration.sub(0, 0, store.gravity);
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linearAcceleration = linearAcceleration.sub(0, 0, store.gravity);
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// add effect of Coriolis acceleration
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store.coriolisAcceleration = status.getSimulationConditions().getGeodeticComputation()
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.getCoriolisAcceleration(status.getRocketWorldPosition(), status.getRocketVelocity());
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store.linearAcceleration = store.linearAcceleration.add(store.coriolisAcceleration);
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linearAcceleration = linearAcceleration.add(store.coriolisAcceleration);
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// If still on the launch rod, project acceleration onto launch rod direction and
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// set angular acceleration to zero.
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if (!status.isLaunchRodCleared()) {
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store.linearAcceleration = store.launchRodDirection.multiply(store.linearAcceleration.dot(store.launchRodDirection));
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store.angularAcceleration = Coordinate.NUL;
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store.rollAcceleration = 0;
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store.lateralPitchAcceleration = 0;
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linearAcceleration = store.launchRodDirection.multiply(linearAcceleration.dot(store.launchRodDirection));
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angularAcceleration = Coordinate.NUL;
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} else {
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@ -366,24 +368,18 @@ public class RK4SimulationStepper extends AbstractSimulationStepper {
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double momY = Cm * dynP * refArea * refLength;
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double momZ = store.forces.getCroll() * dynP * refArea * refLength;
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// Compute acceleration in rocket coordinates
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store.angularAcceleration = new Coordinate(momX / store.rocketMass.getLongitudinalInertia(),
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// Compute angular acceleration in rocket coordinates
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angularAcceleration = new Coordinate(momX / store.rocketMass.getLongitudinalInertia(),
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momY / store.rocketMass.getLongitudinalInertia(),
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momZ / store.rocketMass.getRotationalInertia());
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store.rollAcceleration = store.angularAcceleration.z;
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// TODO: LOW: This should be hypot, but does it matter?
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store.lateralPitchAcceleration = MathUtil.max(Math.abs(store.angularAcceleration.x),
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Math.abs(store.angularAcceleration.y));
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store.angularAcceleration = store.thetaRotation.rotateZ(store.angularAcceleration);
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angularAcceleration = store.thetaRotation.rotateZ(angularAcceleration);
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// Convert to world coordinates
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store.angularAcceleration = status.getRocketOrientationQuaternion().rotate(store.angularAcceleration);
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angularAcceleration = status.getRocketOrientationQuaternion().rotate(angularAcceleration);
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}
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return new AccelerationData(null, null, store.linearAcceleration, store.angularAcceleration, status.getRocketOrientationQuaternion());
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return new AccelerationData(null, null, linearAcceleration, angularAcceleration, status.getRocketOrientationQuaternion());
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}
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