git.gag.com Git - debian/openrocket/blob - src/net/sf/openrocket/optimization/rocketoptimization/parameters/StabilityParameter.java

   1 package net.sf.openrocket.optimization.rocketoptimization.parameters;
   2
   3 import net.sf.openrocket.aerodynamics.AerodynamicCalculator;
   4 import net.sf.openrocket.aerodynamics.BarrowmanCalculator;
   5 import net.sf.openrocket.aerodynamics.FlightConditions;
   6 import net.sf.openrocket.document.Simulation;
   7 import net.sf.openrocket.l10n.Translator;
   8 import net.sf.openrocket.logging.LogHelper;
   9 import net.sf.openrocket.masscalc.BasicMassCalculator;
  10 import net.sf.openrocket.masscalc.MassCalculator;
  11 import net.sf.openrocket.masscalc.MassCalculator.MassCalcType;
  12 import net.sf.openrocket.optimization.general.OptimizationException;
  13 import net.sf.openrocket.optimization.rocketoptimization.OptimizableParameter;
  14 import net.sf.openrocket.rocketcomponent.Configuration;
  15 import net.sf.openrocket.rocketcomponent.RocketComponent;
  16 import net.sf.openrocket.rocketcomponent.SymmetricComponent;
  17 import net.sf.openrocket.startup.Application;
  18 import net.sf.openrocket.unit.UnitGroup;
  19 import net.sf.openrocket.util.Coordinate;
  20 import net.sf.openrocket.util.MathUtil;
  21 import net.sf.openrocket.util.Prefs;
  22
  23 /**
  24  * An optimization parameter that computes either the absolute or relative stability of a rocket.
  25  *
  26  * @author Sampo Niskanen <sampo.niskanen@iki.fi>
  27  */
  28 public class StabilityParameter implements OptimizableParameter {
  29
  30         private static final LogHelper log = Application.getLogger();
  31         private static final Translator trans = Application.getTranslator();
  32
  33
  34         private final boolean absolute;
  35
  36         public StabilityParameter(boolean absolute) {
  37                 this.absolute = absolute;
  38         }
  39
  40
  41         @Override
  42         public String getName() {
  43                 return trans.get("name") + " (" + getUnitGroup().getDefaultUnit().getUnit() + ")";
  44         }
  45
  46         @Override
  47         public double computeValue(Simulation simulation) throws OptimizationException {
  48                 Coordinate cp, cg;
  49                 double cpx, cgx;
  50                 double stability;
  51
  52                 log.debug("Calculating stability of simulation, absolute=" + absolute);
  53
  54                 /*
  55                  * These are instantiated each time because this class must be thread-safe.
  56                  * Caching would in any case be inefficient since the rocket changes all the time.
  57                  */
  58                 AerodynamicCalculator aerodynamicCalculator = new BarrowmanCalculator();
  59                 MassCalculator massCalculator = new BasicMassCalculator();
  60
  61
  62                 Configuration configuration = simulation.getConfiguration();
  63                 FlightConditions conditions = new FlightConditions(configuration);
  64                 conditions.setMach(Prefs.getDefaultMach());
  65                 conditions.setAOA(0);
  66                 conditions.setRollRate(0);
  67
  68                 cp = aerodynamicCalculator.getWorstCP(configuration, conditions, null);
  69                 cg = massCalculator.getCG(configuration, MassCalcType.LAUNCH_MASS);
  70
  71                 if (cp.weight > 0.000001)
  72                         cpx = cp.x;
  73                 else
  74                         cpx = Double.NaN;
  75
  76                 if (cg.weight > 0.000001)
  77                         cgx = cg.x;
  78                 else
  79                         cgx = Double.NaN;
  80
  81
  82                 // Calculate the reference (absolute or relative)
  83                 stability = cpx - cgx;
  84
  85                 if (!absolute) {
  86                         double diameter = 0;
  87                         for (RocketComponent c : configuration) {
  88                                 if (c instanceof SymmetricComponent) {
  89                                         double d1 = ((SymmetricComponent) c).getForeRadius() * 2;
  90                                         double d2 = ((SymmetricComponent) c).getAftRadius() * 2;
  91                                         diameter = MathUtil.max(diameter, d1, d2);
  92                                 }
  93                         }
  94                         stability = stability / diameter;
  95                 }
  96
  97                 log.debug("Resulting stability is " + stability + ", absolute=" + absolute);
  98
  99                 return stability;
 100         }
 101
 102         @Override
 103         public UnitGroup getUnitGroup() {
 104                 if (absolute) {
 105                         return UnitGroup.UNITS_LENGTH;
 106                 } else {
 107                         return UnitGroup.UNITS_STABILITY_CALIBERS;
 108                 }
 109         }
 110
 111 }