Module MAPLEAF.Rocket.CompositeObject
Both Stage and Rocket objects inherit from CompositeObject.
It implements functionality to add forces and inertias from an arbitrary number of subcomponents.
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'''
Both `MAPLEAF.Rocket.Stage` and `MAPLEAF.Rocket.Rocket` objects inherit from `CompositeObject`.
It implements functionality to add forces and inertias from an arbitrary number of subcomponents.
'''
from MAPLEAF.Motion import ForceMomentSystem, Inertia, Vector
from MAPLEAF.Utilities import cacheLastResult
from MAPLEAF.Rocket import FixedMass
__all__ = [ 'CompositeObject' ]
class CompositeObject():
"""
Represents a collection of physical objects with masses.
Expects:
Components to have the following methods:
.getAppliedForce(state, time, environmentalConditions, rocketCG)
.getInertia(time)
.getMass(time) (optional as long as getInertia is implemented)
Objects that inherit from FixedMass to be fixed mass objects. Their inertias are cached and not recomputed
Objects that do not inherit from FixedMass to be variable mass objects. Their inertias are recalculated all the time.
"""
def __init__(self, components=[], CGOverride=None, MOIOverride=None, massOverride=None):
self.components = components
self.CGOverride = CGOverride
self.MOIOverride = MOIOverride
self.massOverride = massOverride
# Initialize lists of fixed and variable-mass components
self.fixedMassComponents = []
self.variableMassComponents = []
self._initializeComponentLists()
# Pre-calculate inertia of all fixed-mass components
self.fixedMassInertiaComponent = None
self.fixedMassMassComponent = None
self._initializeFixedMassInertia()
#TODO: Add ability to override aero-properties
def _initializeComponentLists(self):
# Sort component lists
self.fixedMassComponents = []
self.variableMassComponents = []
for component in self.components:
if isinstance(component, FixedMass):
self.fixedMassComponents.append(component)
else:
self.variableMassComponents.append(component)
def _initializeFixedMassInertia(self):
if len(self.fixedMassComponents) > 0:
inertiasList = []
for fixedMassComponent in self.fixedMassComponents:
inertiasList.append(fixedMassComponent.getInertia(0, None))
self.fixedMassInertiaComponent = inertiasList[0].combineInertias(inertiasList)
self.fixedMassMassComponent = self.fixedMassInertiaComponent.mass
else:
self.fixedMassInertiaComponent = Inertia(Vector(0,0,0), Vector(0,0,0), 0)
self.fixedMassMassComponent = 0
def recomputeFixedMassInertia(self):
''' Intended to be called if fixedMass components are added/removed or modified from the composite object '''
self._initializeComponentLists()
self._initializeFixedMassInertia()
# Try to recompute inertias of sub-object, in case any of them are also CompositeObjects
# This happens in the case of a Rocket, where the components are Stages (also CompositeObjects)
for component in self.components:
try:
component.recomputeFixedMassInertia()
except AttributeError:
pass # Not a CompositeObject
#TODO: Compute forces at interfaces between components
@cacheLastResult
def getAppliedForce(self, state, time, environmentalConditions, rocketCG):
'''
Computes the aerodynamic force experienced by the stage.
Does not include gravitational force - gravity is added at the rocket level.
'''
# Add up forces from all subcomponents
totalAppliedComponentForce = ForceMomentSystem(Vector(0,0,0), rocketCG)
for component in self.components:
componentForce = component.getAppliedForce(state, time, environmentalConditions, rocketCG)
# Log applied forces and moments if desired
if hasattr(component, "forcesLog"):
component.forcesLog.append(componentForce.force)
component.momentsLog.append(componentForce.moment)
totalAppliedComponentForce += componentForce
return totalAppliedComponentForce
@cacheLastResult
def getInertia(self, time, state):
''' Returns an Inertia object, used for 6DoF computations '''
# Add up component inertias
inertiasList = [ self.fixedMassInertiaComponent ]
for component in self.variableMassComponents:
inertiasList.append(component.getInertia(time, state))
combinedInertia = inertiasList[0].combineInertias(inertiasList)
# Overrides
if self.CGOverride != None:
combinedInertia.CG = self.CGOverride
combinedInertia.MOICentroidLocation = self.CGOverride
if self.MOIOverride != None:
combinedInertia.MOI = self.MOIOverride
if self.massOverride != None:
combinedInertia.mass = self.massOverride
return combinedInertia
def getMass(self, time, state):
'''
Returns an inertia object where the CG and MOI members are zero.
Only the mass is filled out correctly.
Used for 3DoF computations
'''
if self.massOverride == None:
totalMass = self.fixedMassMassComponent
for component in self.variableMassComponents:
try:
totalMass += component.getMass(time, state).mass
except AttributeError:
totalMass += component.getInertia(time, state).mass
else:
return self.massOverride
return totalMass
def getCG(self, time, state):
return self.getInertia(time, state).CGClasses
class CompositeObject (components=[], CGOverride=None, MOIOverride=None, massOverride=None)-
Represents a collection of physical objects with masses.
Expects:
Components to have the following methods:
.getAppliedForce(state, time, environmentalConditions, rocketCG)
.getInertia(time)
.getMass(time) (optional as long as getInertia is implemented)
Objects that inherit from FixedMass to be fixed mass objects. Their inertias are cached and not recomputed
Objects that do not inherit from FixedMass to be variable mass objects. Their inertias are recalculated all the time.Expand source code
class CompositeObject(): """ Represents a collection of physical objects with masses. Expects: Components to have the following methods: .getAppliedForce(state, time, environmentalConditions, rocketCG) .getInertia(time) .getMass(time) (optional as long as getInertia is implemented) Objects that inherit from FixedMass to be fixed mass objects. Their inertias are cached and not recomputed Objects that do not inherit from FixedMass to be variable mass objects. Their inertias are recalculated all the time. """ def __init__(self, components=[], CGOverride=None, MOIOverride=None, massOverride=None): self.components = components self.CGOverride = CGOverride self.MOIOverride = MOIOverride self.massOverride = massOverride # Initialize lists of fixed and variable-mass components self.fixedMassComponents = [] self.variableMassComponents = [] self._initializeComponentLists() # Pre-calculate inertia of all fixed-mass components self.fixedMassInertiaComponent = None self.fixedMassMassComponent = None self._initializeFixedMassInertia() #TODO: Add ability to override aero-properties def _initializeComponentLists(self): # Sort component lists self.fixedMassComponents = [] self.variableMassComponents = [] for component in self.components: if isinstance(component, FixedMass): self.fixedMassComponents.append(component) else: self.variableMassComponents.append(component) def _initializeFixedMassInertia(self): if len(self.fixedMassComponents) > 0: inertiasList = [] for fixedMassComponent in self.fixedMassComponents: inertiasList.append(fixedMassComponent.getInertia(0, None)) self.fixedMassInertiaComponent = inertiasList[0].combineInertias(inertiasList) self.fixedMassMassComponent = self.fixedMassInertiaComponent.mass else: self.fixedMassInertiaComponent = Inertia(Vector(0,0,0), Vector(0,0,0), 0) self.fixedMassMassComponent = 0 def recomputeFixedMassInertia(self): ''' Intended to be called if fixedMass components are added/removed or modified from the composite object ''' self._initializeComponentLists() self._initializeFixedMassInertia() # Try to recompute inertias of sub-object, in case any of them are also CompositeObjects # This happens in the case of a Rocket, where the components are Stages (also CompositeObjects) for component in self.components: try: component.recomputeFixedMassInertia() except AttributeError: pass # Not a CompositeObject #TODO: Compute forces at interfaces between components @cacheLastResult def getAppliedForce(self, state, time, environmentalConditions, rocketCG): ''' Computes the aerodynamic force experienced by the stage. Does not include gravitational force - gravity is added at the rocket level. ''' # Add up forces from all subcomponents totalAppliedComponentForce = ForceMomentSystem(Vector(0,0,0), rocketCG) for component in self.components: componentForce = component.getAppliedForce(state, time, environmentalConditions, rocketCG) # Log applied forces and moments if desired if hasattr(component, "forcesLog"): component.forcesLog.append(componentForce.force) component.momentsLog.append(componentForce.moment) totalAppliedComponentForce += componentForce return totalAppliedComponentForce @cacheLastResult def getInertia(self, time, state): ''' Returns an Inertia object, used for 6DoF computations ''' # Add up component inertias inertiasList = [ self.fixedMassInertiaComponent ] for component in self.variableMassComponents: inertiasList.append(component.getInertia(time, state)) combinedInertia = inertiasList[0].combineInertias(inertiasList) # Overrides if self.CGOverride != None: combinedInertia.CG = self.CGOverride combinedInertia.MOICentroidLocation = self.CGOverride if self.MOIOverride != None: combinedInertia.MOI = self.MOIOverride if self.massOverride != None: combinedInertia.mass = self.massOverride return combinedInertia def getMass(self, time, state): ''' Returns an inertia object where the CG and MOI members are zero. Only the mass is filled out correctly. Used for 3DoF computations ''' if self.massOverride == None: totalMass = self.fixedMassMassComponent for component in self.variableMassComponents: try: totalMass += component.getMass(time, state).mass except AttributeError: totalMass += component.getInertia(time, state).mass else: return self.massOverride return totalMass def getCG(self, time, state): return self.getInertia(time, state).CGSubclasses
Methods
def getAppliedForce(*args)-
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def memoized_func(*args): # Return cached result if available if cache[1] == args: return cache[2] # Compute and cache result result = func(*args) cache[1] = args cache[2] = result return result def getCG(self, time, state)-
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def getCG(self, time, state): return self.getInertia(time, state).CG def getInertia(*args)-
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def memoized_func(*args): # Return cached result if available if cache[1] == args: return cache[2] # Compute and cache result result = func(*args) cache[1] = args cache[2] = result return result def getMass(self, time, state)-
Returns an inertia object where the CG and MOI members are zero. Only the mass is filled out correctly. Used for 3DoF computations
Expand source code
def getMass(self, time, state): ''' Returns an inertia object where the CG and MOI members are zero. Only the mass is filled out correctly. Used for 3DoF computations ''' if self.massOverride == None: totalMass = self.fixedMassMassComponent for component in self.variableMassComponents: try: totalMass += component.getMass(time, state).mass except AttributeError: totalMass += component.getInertia(time, state).mass else: return self.massOverride return totalMass def recomputeFixedMassInertia(self)-
Intended to be called if fixedMass components are added/removed or modified from the composite object
Expand source code
def recomputeFixedMassInertia(self): ''' Intended to be called if fixedMass components are added/removed or modified from the composite object ''' self._initializeComponentLists() self._initializeFixedMassInertia() # Try to recompute inertias of sub-object, in case any of them are also CompositeObjects # This happens in the case of a Rocket, where the components are Stages (also CompositeObjects) for component in self.components: try: component.recomputeFixedMassInertia() except AttributeError: pass # Not a CompositeObject