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