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![Lab2 Classes
The Cadac hierarchy
Abstract base class Cadac
Hierarchy Virtual functions
Derived class Round3 newton ( )
round3 [ ] environment ( )
Virtual functions
Derived class Target Cruise Satellite
target [ ] cruise [ ] satellite [ ] Module-Variable arrays aerodynamics ( )
propulsion ( )
SATELLITE3 forces ( )
Vehicle names TARGET3 CRUISE3
targeting ()
seeker ( )
guidance ( )
control ( )
Communication bus combus [ ] intercept ()
aerodynamics ( ) propulsion ( ) forces ( ) newton ( ) intercept ( )
Modular structure seeker ( )
control ( ) guidance ( ) environment ( )
SCHEDULE targeting ( )
♣
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![Lab2 Classes
Abstract base class Cadac
• Cadac declares
– Pointers of module-variable arrays
Run-Time – Pure virtual functions for the executive processes
Polymorphism – Pure virtual functions for the modules
class Cadac
{
private:
char name[CHARN]; //vehicle object name
protected:
//module-variable array of class 'Round3'
CRUISE_2 Variable *round3;
//module-variable array of class 'Cruise'
Variable *cruise;
//module-variable array of class 'Target'
Variable *target;
//module-variable array of class 'Satellite'
Variable *satellite;
class Variable
public: {
Cadac(){} private:
virtual~Cadac(){}; char name[CHARN];
//executive functions char type[CHARN];
//pure virtual functions double rval;
virtual void sizing_arrays()=0; int ival;
.... Matrix VEC;
//module functions Matrix MAT;
//... pure virtual functions char def[CHARL];
}; char mod[CHARN];
char role[CHARN];
char out[CHARN];
public:
//methods for initialization
//methods for reading and loading ♣
};
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![Lab2 Classes
Cruise inherits from Round3
class Cruise:public Round3
• Bank-to-turn UAV {
protected:
void Cruise::aerodynamics(); //name of “CRUISE3” vehicle object
char cruise3_name[CHARL];
Modules Drag polar //array pointers
...
void Cruise::propulsion(...); public:
Cruise(){};
Cruise(...);
Turbojet virtual~Cruise();
void Cruise::forces(); //executive functions
...
Aerodynamic and propulsive
//module functions
void Cruise::control(...); virtual void aerodynamics();
virtual void propulsion(...);
CRUISE_2 virtual void forces();
Heading, flight path, bank angle, load virtual void control(...);
virtual void guidance();
factor, altitude hold virtual void targeting(...);
virtual void seeker(...);
void Cruise::guidance(); virtual void intercept(...);
Line, pro-nav, point, arc //functions of control module
double control_heading(...);
void Cruise::targeting(...); double control_flightpath(...);
double control_bank(...);
double control_load(...);
Satellite targeting double control_lateral(...);
double control_altitude(...);
void Cruise::seeker(...);
//functions of guidance module
Line-of-sight seeker Matrix guidance_line();
Matrix guidance_pronav();
void Cruise::intercept(...); Matrix guidance_point();
double guidance_arc();
double guidance_spline();
Waypoint and target miss distance
//functions of seeker module
void seeker_grnd_ranges(...);
//functions of targeting module
void targeting_satellite(...);
void targeting_grnd_ranges(...); ♣
};
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![Lab2 Classes
Target inherits from Round3
CADAC
class Target:public Round3
Hierarchy
{
protected:
//name of “TARGET3” vehicle object
char target3_name[CHARL];
//array pointers
...
public:
Target(){};
CRUISE_2
Target(...);
virtual~Target();
//executive functions
...
• Target over the round, rotating Earth //module function dummy returns
virtual void def_aerodynamics(){};
void Target::forces(); ...
//module functions active
Compensating for Coriolis and virtual void forces();
centrifugal accelerations virtual void intercept(...); ♣
};
void Target::intercept(...);
Setting target status (alive, hit, dead)
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![Lab2 Classes
Satellite inherits from Round3
class Satellite:public Round3
{
protected:
//name of ”SATELLITE3” vehicle object
char satellite3_name[CHARL];
//array pointers
...
public:
Satellite(){};
CRUISE_2
Satellite(...);
virtual~Satellite();
//executive functions
...
//module function dummy returns
• Target over the round, rotating Earth virtual void def_aerodynamics(){};
void Satellite::forces(); ...
//module functions active
Mass properties and optional thrusting
virtual void forces();
void Satellite::seeker(...); virtual void seeker(...); ♣
Radar seeker (simplified) };
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![Lab2 Satellite Simulation
Class hierarchy of satellite simulation
Abstract base class Cadac
Virtual functions
Derived class Round3 newton ( )
round3 [ ]
environment ( )
Module-
Derived class
Variable arrays Satellite forces ()
satellite [ ]
SATELLITE3
environment ( ) forces ( ) newton ( )
Modular structure
♣
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![Lab2 Satellite Simulation
Equations of motions are derived from Newton’s Law
Zipfel, p. 261 *
Newton’s Law
mD I v IB = f a , p + mg
Relationship of inertial and geographic
velocities
v IB = v E + Ω EI s BI
B
Matrix equations programmed in ‘newton’ module
(
m [dvB / dt ]I = [T ]GI [T ]VG [ f a , p ]V + m [ g ]G
I
) I Inertial coordinates
[dsBI / dt ] = [v ]
I I I
B G Geographic coordinates
* “Modeling and V Flight path coordinates
Simulation of
Aerospace Vehicle
Dynamics”, AIAA
Education Series, 2nd ♣
Edition, 2007
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![Lab2 Satellite Simulation
Inertial and Earth coordinate systems
• Inertial coordinate system
1I axis is aligned with the Vernal Equinox
3I axis is aligned with the spin axes of the
Earth
Zipfel, p. 71
• Angle Ξ is the hour angle
• The transformation matrix of Earth wrt inertial coordinates is
⎡ cos Ξ sin Ξ 0⎤
[T ]EI = ⎢− sin Ξ cos Ξ 0⎥ ♣
⎢ ⎥
⎢
⎣ 0 0 1⎥
⎦
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![Lab2 Satellite Simulation
Earth and geographic coordinate systems
• Earth coordinate system
1E axis is at the intersection of the Greenwich
Meridian and the equator
3E axis is aligned with the spin axis of the Earth
Zipfel, p. 72
• Geographic coordinate system
1G axis points to the north pole
3G axis point to the center of the Earth
• l longitude
• λ latitude
• TM sequences through two intermediate coordinate systems X and Y
[T ]GE = [T (180o )]GY [T (90o − λ )]YX [T (l )]XE
• The TM of geographic wrt Earth coordinates is
⎡ − sin λ cos l − sin λ sin l cos λ ⎤
[T ]GE = ⎢ − sin l cos l 0 ⎥♣
⎢ ⎥
⎢− cos λ cos l − cos λ sin l − sin λ ⎥
⎣ ⎦
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![Lab2 Satellite Simulation
Geographic and flight path coordinate system
• Geographic coordinate system
1G axis points to the north pole
1V 3G axis point to the center of the Earth
• Flight path coordinate system
Zipfel, p. 80 1G
2V
2G X
1V axis parallel and in the direction of the
2X 1 velocity vector
2V axis is horizontal and points to the right
3V 3V axis point “down”
• χ heading angle (chi)
X
3 = 3G
• γ flight-path angle
• The TM of flight path wrt geographic coordinates is
[T ]VG = [T (γ )]VX [T ( χ )] XG
⎡cos γ 0 − sin γ ⎤ ⎡ cos χ sin χ 0⎤ ⎡cos γ cos χ cos γ sin χ − sin γ ⎤
[T ]VG =⎢ 0 1 0 ⎥ ⎢− sin χ cos χ 0⎥ = ⎢ − sin χ cos χ 0 ⎥ ♣
⎢ ⎥⎢ ⎥ ⎢ ⎥
⎢ sin γ
⎣ 0 cos γ ⎥ ⎣ 0
⎦⎢ 0 1⎥ ⎢ sin γ cos χ
⎦ ⎣ sin γ sin χ cos γ ⎥⎦
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![Lab2 Satellite Simulation
Geographic initialization
• Geographic initialization converted to inertial position and velocity
CRUISE_2 Implemented in: void Round3::init_newton()
E Geographic speed
| vB |
χ Heading angle
γ Flight path angle
| v B | , χ , γ , l, λ , h
E
l Longitude
λ Latitude
h Altitude
E
| vB |
[T ]GE = cadtge( l, λ)
[ s BI ] I
[sBI ]E = [T ]EG[sBI ]G Inertial position
[vB ]G = cart_ from_ pol | vB |, χ, γ
E E
( ) [v B ] I
I
Inertial velocity
[T ] = [E]
IE
GV
[T ]IG = [T ]IE[T ]EG [T ] T.M. of geographic wrt flight path coor.
[vB ]I = [T ]IG[vB ]G + [ΩEI ]I [sBI ]I
I E
[T ] IG T.M. of inertial wrt geographic coor.
VG
[T ] = mat2tr( χ, γ )
[T ]GV = [T ]VG
♣
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![Lab2 Satellite Simulation
Solving the equations of motion
• Integrating inertial states and converting them to geographic output
CRUISE_2 Implemented in: void Round3::newton(double int_step)
[ f sp ]V Propulsive specific force
(
[ dvB / dt ]I = [T ]IG [T ]GV [ f sp ]V + [ g ]G
I
)
[ dsBI / dt ]I = [ vB ]I
I
E
| vB |
[T ] EI = cadtei (time)
χ
γ
[ s BI ] E = [T ] EI [ s BI ] I
(l , λ , h ) = cadsph ([ s BI ]E )
l
λ
[T ]GE = cadtge (l , λ ) h
[T ]GI = [T ]GE [T ] EI
(
[v B ]G = [T ]GI [v B ] I − [Ω EI ] I [ s BI ] I
E I
)
( | v B |, χ , γ
E
) = pol _ from _ cart ( [v B ]G
E
)
[T ] VG
= mat 2tr ( χ , γ )
[T ]GV = [T ]VG
♣
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![Lab3 Modules
Modules are called every integration cycle
Calling sequence established in
input.asc
MODULES
environment def,init,exec struct Module
aerodynamics def,exec {
propulsion def,init,exec string name;
forces def,exec string definition;
newton def,init,exec string initialization;
targeting def,exec string execution;
seeker def,exec string termination;
guidance def,exec };
control def,exec
intercept def,exec
END
Loading modules into module_list
void order_modules(fstream &input,int &num,Module *module_list)
Module calling
//Vehicle’s constructor calls module to define module-variables
if((module_list[j].name==“newton")&&(module_list[j].definition=="def"))
def_newton();
//Module is initialized in ‘main()’
if((module_list[j].name==“newton")&&(module_list[j].initialization=="init"))
vehicle_list[i]->init_newton();
//Every integration step, module is called in ‘execute(…)’
if(module_list[j].name==“newton")
vehicle_list[i]->newton(int_step);
♣
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![Lab3 Modules
Module-variables are of type Variable
class Variable
{
Defining module-variables in void Round3::def_newton() private:
char name[CHARN];
round3[19].init("lonx",0,"Vehicle longitude - deg","newton","diag","scrn,plot,com"); char type[CHARN];
double rval;
round3[20].init("latx",0,"Vehicle latitude - deg","newton","diag","scrn,plot,com"); int ival;
Matrix VEC;
round3[21].init("alt",0,"Vehicle altitude - m","newton","out","scrn,plot,com"); Matrix MAT;
char def[CHARL];
Documenting module-variables in doc.asc char mod[CHARN];
char role[CHARN];
char out[CHARN];
Round3 Module-Variable Array public:
methods to initialize
---------------------------------------------------------------------------------------------------------------------
|LOC| NAME | DEFINITION | methods to read OUTPUT
MODULE | PURPOSE | and load|
---------------------------------------------------------------------------------------------------------------------
};
…………………………………………………………
19 lonx Vehicle longitude - deg newton diag scrn,plot,com
20 latx Vehicle latitude - deg newton diag scrn,plot,com
21 alt Vehicle altitude - m newton out scrn,plot,com
…………………………………………………………
Using module-variables
void Round3::newton(double int_step)
{
//localizing module-variables
//input from other modules
double time=round3[0].real();
Matrix FSPV=round3[10].vec();
...
//-----------------------------------------
... computations ...
//-------------------------------------------
//loading module-variables
//state variables
round3[35].gets_vec(SBII);
round3[36].gets_vec(VBII);
♣
...
}
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![Lab3 Modules
Example code of module ‘newton’
CRUISE_3 void Round3::def_newton()
{
name, value, definition, module, type, out to: screen, plot file, combus
Definition of //Definition of module-variables
module-variables round3[19].init("lonx",0,"Vehicle longitude-deg","newton","diag","scrn,plot,com");
round3[20].init("latx",0,"Vehicle latitude-deg","newton","diag","scrn,plot,com");
in array ‘round3[ ]’, round3[21].init("alt",0,"Vehicle altitude-m","newton","out","scrn,plot,com");
a member of class ...
‘Round3’ }void Round3::init_newton()
{
........................
}
void Round3::newton(double int_step)
{
//localizing module-variables
Getting module- //input from other modules
double time=round3[0].real();
variables from Matrix FSPV=round3[10].vec();
‘round3[ ]’ array double grav=round3[11].real();
Matrix WEII=round3[27].mat();
//state variables
Matrix SBII=round3[35].vec();
Matrix VBII=round3[36].vec();
Matrix ABII=round3[37].vec();
...
//-------------------------------------------------------------------------
//building gravitational vector in geographic coordinates
GRAV.assign_loc(2,0,grav);
//integrating inertial state variables
Computations ABII_NEW=TIG*((TGV*FSPV)+GRAV);
VBII_NEW=integrate(ABII_NEW,ABII,VBII,int_step);
SBII=integrate(VBII_NEW,VBII,SBII,int_step);
ABII=ABII_NEW;
VBII=VBII_NEW;
...
//-------------------------------------------------------------------------
//loading module-variables
Loading module- //state variables
variables onto round3[35].gets_vec(SBII);
round3[36].gets_vec(VBII);
‘round3[ ]’ array round3[37].gets_vec(ABII);
♣
...
}
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![Lab3 Modules
How to build a module
1. Start with sample module as template Example: Newton Module
2. Reserve contiguous slots in the module-array
3. In ‘def_module’ categorize module-variables as /////////////////////////////////////////////////
//Definition of newton module-variables
"data" input data values //Member function of class 'Round3'
"init" initialized in init_module //Module-variable locations are assigned
// to round3[17-39]
"state" state variables for integration //000624 Created by Michael Chiaramonte
"out" output to other modules /////////////////////////////////////////////////
"diag" diagnostic, not used by other modules void Round3::def_newton()
{
"save" value saved for next cycle
4. In ‘module’ localize module-variables by category //Definition of module-variables
round3[19].init("lonx",0,"Vehicle longitude-d
//input data round3[20].init("latx",0,"Vehicle latitude-deg
//restore saved values round3[21].init("alt",0,"Vehicle altitude-m","
//state variables }void Round3::init_newton()
//input from other modules {
5. Insert computations ........................
}
6. In ‘module’ load module-variables by category void Round3::newton(double int_step)
CRUISE_3 //state variables {
//saving values //localizing module-variables
//input from other modules
//output to other modules double time=round3[0].real();
//diagnostics Matrix FSPV=round3[10].vec();
double grav=round3[11].real();
7. Incorporate new module into simulation frame Matrix WEII=round3[27].mat();
//state variables
Definition module is called once, before ‘input.asc’ Matrix SBII=round3[35].vec();
Matrix VBII=round3[36].vec();
Defines all module-variables Matrix ABII=round3[37].vec();
...
Directs variables to output streams //------------------------------------------
Initialization module is called once, after ‘input.asc’ //building gravitational vector in geographic
GRAV.assign_loc(2,0,grav);
Executes initial calculations
Module is called once every integration step //integrating inertial state variables
ABII_NEW=TIG*((TGV*FSPV)+GRAV);
Localizes module-variables VBII_NEW=integrate(ABII_NEW,ABII,VBII,int_step);
Executes computations every integration step SBII=integrate(VBII_NEW,VBII,SBII,int_step);
ABII=ABII_NEW;
Integrates state variables VBII=VBII_NEW;
...
Calls other subordinate functions //--------------------------------------------
Calls utility subroutines //loading module-variables
//state variables
Performs table look-up round3[35].gets_vec(SBII);
Loads module-variables round3[36].gets_vec(VBII);
round3[37].gets_vec(ABII);
Watch out ...
Initialize all local variables }
Don’t call other module’s subordinate functions ♣
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![Lab3 Modules
Matrix utility operations
• Source code should be programmed in matrices as much as possible
– Compact code
– Avoids errors
• Requirements of flight simulations
– Mostly 3x1 and 3x3 matrices, some of higher dimensions (Kalman filters)
– Elements of matrices are of type double
• Class Matrix instantiate a pointer to the matrix *pbody and
initializes the elements to zero
• Examples from module Target::forces()
CRUISE_3 //Coriolis acceleration in V-coordinates
WEIG=TGE*WEII*TEG;
CORIO_V=TVG*WEIG*VBEG*2;
//centrifugal acceleration in V-coordinates
CENTR_V=TVG*WEIG*WEIG*TGI*SBII;
• Special features
– All matrix manipulations are carried out in pointer arithmetic
– Creating a matrix returns *this of the initialized matrix
– Usage of copy constructor for the matrix assignment operator
– Overloaded offset operator [] ♣
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;
Matrix sub_matrix(const int &row, const int &col); double operator^(const Matrix &B);
Matrix trans();
Matrix operator~();
Matrix univec3();
Matrix & zero();
Matrix vec9_mat33();
♣
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![Lab3 Target Simulation
Class hierarchy of target simulation
CRUISE_3
Abstract base class Cadac
Virtual functions
Derived class Round3 newton ( )
environment ( )
round3 [ ]
Module-
Derived class
Variable arrays Target forces( )
target [ ] intercept ( )
TARGET3
environment ( ) forces ( ) newton ( ) intercept ( )
Modular structure
♣
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![Lab3 Target Simulation
Equations of motions are compensated
• Newton’s Law governs the motion of the target
• Compensating forces are applied to constrain
the target to the surface of the Earth
Newton’s Law with compensation ma comp
mD I v I = ma comp + mg
B
Matrix equations programmed in ‘newton’ module
I Inertial coordinates
(
[dv B / dt ] I = [T ]GI [T ]VG [acomp ]V + [ g ]G
I
) G Geographic coordinates
V Flight path coordinates
♣
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Uploaded byJim Jenkins
ATI Technical Training Short Course Aerospace Simulations In C++
This document describes a four-day course on building aerospace simulations in C++. The course uses a hierarchy of classes based on an abstract base class called Cadac to build simulations of satellites, unmanned vehicles, and missiles. Students will learn how to model vehicle dynamics, aerodynamics, propulsion, guidance and control by working with provided C++ simulations throughout the course. The instructor has over 40 years of experience in modeling and simulation.
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ATI Technical Training Short Course Aerospace Simulations In C++
- 1. Professional Development ShortCourse On: Aerospace Simulations In C++ Instructor: Dr. Peter Zipfel ATI Course Schedule: http://www.ATIcourses.com/schedule.htm http://www.aticourses.com/aerospace_simulations_in_C++.htm ATI's Aerospace Simulations In C++ :
- 2. Aerospace Simulations inC++ Apply the power of C++ to simulate multi-object aerospace vehicles $1995 Summary This four-day course introduces engineers and programmers to object oriented programming of aerospace vehicle simulations. Building on your basic understanding of C++, this course will bring Participants may bring an IBM compatible laptop with Microsoft Visual NEW! alive polymorphism, inheritance and encapsulation C++ 2005 or 2008 installed (free download) or Visual FORTRAN 6.1 by hands-on experimentation with simulations of or later (currently sold by Intel). satellites, unmanned combat air vehicles, and air intercept missiles. Lecture and computer lab will guide you from single object architectures to Course Outline multiple interacting vehicles. Demonstrations on 1. Building the Satellite Simulation. Reviewing C++ basics. Modeling modeling of aerodynamics, propulsion, flight three DoF equations of motions. Introducing the satellite simulation control and navigation & guidance assume some architecture making use of inheritance. Running your first simulation in familiarity with these disciplines. You will take MS Visual C++. Exploring the characteristics of satellite trajectories. home five simulations with plotting utilities, ready 2. Building the Truck Simulation. Converting to the truck simulation. to run, and the instructor’s textbook Modeling and Understanding C++ input, and object replication. Experimenting with Simulation of Aerospace Vehicle Dynamics. multiple vehicles moving on the ground. 3. Building the Unmanned Combat Air Vehicle (UCAV) Simulation. Understanding aerodynamic and propulsion modeling. Applying run-time Hands-On Training polymorphism to the UCAV class hierarchy. Understanding flight control. During this course, under the instructor’s Exploring utility classes and operator overloading. Using output files for guidance, you gain extensive C++ experience plotting. Understanding navigation and guidance. Combining UCAV and working ‘real-world’ aerospace simulations on truck targets for attack trajectory studies. supplied PCs: 4. Merging the Satellite, Truck and UCAV Simulations. Studying the • Compiling and running C++ simulations in MS run-time interface communication among the vehicles. Running multi- Visual C++ vehicle, multi-object trajectories and displaying them graphically. • Defining and using classes 5. Investigating the Air Intercept Missile Simulation. Understanding a • Building class hierarchies typical six DoF missile simulation. Modeling interaction of missiles and targets. Conducting air-to-air engagement studies. • Reading and writing formatted I/O • Applying run-time polymorphism • Running, plotting and interpreting satellite, Included with this short course is the instructor’s text book UCAV and missile trajectories “Modeling and Simulation of Aerospace Vehicle Dynamics”, a complete set of course notes, five C++ simulations, and a free CD-ROM with CADAC-Studio for plotting. Instructor Dr. Peter Zipfel is an Adjunct Associate Professor at the University of Florida and has What You Will Learn taught courses in Modeling & Simulation in C++, • Exploiting the rich features of C++ for aerospace application Flight Dynamics, Guidance and Control for the last • How to use classes and inheritance to build vehicle objects twenty years. His forty years of M&S experience • How run-time polymorphism makes multi-object simulations possible in helicopters, missiles, aircraft and hypersonic • How the run-time interface communicates among vehicles vehicles was acquired at the German Helicopter • Understanding three and six DoF aerospace simulations Institute, the U.S. Army and U.S. Air Force and his • How a vehicle is subdivided into subsystem modules consulting business Modeling and Simulation • How aerodynamics, propulsion, guidance and control are modeled Technologies. Having given short courses on M&S • How C++ facilitates the data exchange between subsystems in the UK, Germany, France and the U.S. he is an internationally recognized lecturer. Recently he • Running aerospace simulations authored the text book Modeling and Simulation of • How to set up input in C++ • How to execute and record the output Aerospace Vehicle Dynamics. • How to plot and interpret the trajectories of satellites, aircraft and missiles Register online at www.ATIcourses.com or call ATI at 888.501.2100 or 410.531.6034
- 3. e e at at lic l ia om lic up er .c up at D es D IM ot rs ot N om AT ou N o Ic o D .c • AT l • D l ia www.ATIcourses.com es te l• er rs a ia w. a ic at om er w ri ou pl M w ate .c at Ic u TI D es M M Boost Your Skills •A ot rs TI 349 Berkshire Drive I AT w. N ou A te Riva, Maryland 21140 AT with On-Site Courses w Do Ic te • .c ca Telephone 1-888-501-2100 / (410) 965-8805 te om es li ca l• om a rs up Tailored to Your Needs Fax (410) 956-5785 w .c lic ia w. li ou D Email: ATI@ATIcourses.com w up er es up AT Ic ot at w D rs D AT N M The Applied Technology Institute specializes in training programs for technical professionals. Our courses keep you ot ou ot o current in the state-of-the-art technology that is essential to keep your company on the cutting edge in today’s highly N I Ic N w. D AT competitive marketplace. Since 1984, ATI has earned the trust of training departments nationwide, and has presented o AT Do l• D on-site training at the major Navy, Air Force and NASA centers, and for a large number of contractors. Our training ia l• increases effectiveness and productivity. Learn from the proven best. w. • er w ial ia w at er w er For a Free On-Site Quote Visit Us At: http://www.ATIcourses.com/free_onsite_quote.asp IM at at IM AT IM For Our Current Public Course Schedule Go To: http://www.ATIcourses.com/schedule.htm w AT AT
- 4. Building Aerospace Simulationsin C++ Lab2 Classes … build your world of hierarchies Lab Topics Simulation • CRUISE is built on the Cadac hierarchy 1 C++ Essentials QuickStart CRUISE • The classes of CADAC++ 2 Classes CRUISE_2 • Multiple encapsulated objects Satellite Simulation 3 Modules CRUISE_3 • The Cadac hierarchy Target Simulation Tables • Abstract base class Cadac 4 CRUISE_4 UAV Uncontrolled Events • Round3 inherits from Cadac 5 CRUISE_5 UAV Controlled • Cruise inherits from Round3 Polymorphism 6 CRUISE_6 UAV Navigation • Target inherits from Round3 ComBus 7 CRUISE_7 UAV Homing • Satellite inherits from Round3 Architectures 8 UAV Netcentric CRUISE • What you have learned ♣ SCHEDULE Copyright © 2009 Modeling and Simulation Technologies
- 5. Lab2 Classes CRUISE is built on the Cadac hierarchy • Cadac is the abstract base class Classes – Characterized by the fact that it contains pure virtual functions • Round3 class is derived from Cadac – Provides the structure for the equations of motion • Cruise, Target, and Satellite classes are derived from Round3 – These classes declare the vehicle types with names: CRUISE3, TARGET3, and SATELLITE3 • Modules are member functions of the derived classes – They define the mathematical models of the vehicle components • Other classes support the simulation architecture ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 2
- 6. Lab2 Classes The classes of CADAC++ CLASS DESCRIPTION CADAC Cadac, ... Hierarchical class structure of vehicles Hierarchy Vehicle Hosting a pointer array of type Cadac Module Storing module information Variable Declaring module-variables Event Storing event information Packet Declaring data packets for global communication bus Datadeck Hosting a pointer array of type Table Table Storing tabular data Matrix Storing matrix operations Document Storing module-variable definitions ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 3
- 7. Lab2 Classes Multiple encapsulated objects • Each aerospace vehicle is an object created from its hierarchical class structure – Data and methods (member functions) are encapsulated • Aerodynamic and propulsion data tables • Vehicle characteristics are computed in module functions – Cadac is the abstract base class • Examples Cruise Missile Air Engagement Aircraft Simulation Simulation Simulation Cadac Cadac Cadac Round3 Flat6 Flat6 Flat3 Target Cruise Satellite Plane Missile Recce Target • Polymorphism enables the call of the vehicle objects during run-time Inheritance – Inheritance enables a derived object to acquire the properties of the base object Run-Time Polymorphism – Virtual functions are overridden until the correct module is executed ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 4
- 8. Lab2 Classes The Cadac hierarchy Abstract base class Cadac Hierarchy Virtual functions Derived class Round3 newton ( ) round3 [ ] environment ( ) Virtual functions Derived class Target Cruise Satellite target [ ] cruise [ ] satellite [ ] Module-Variable arrays aerodynamics ( ) propulsion ( ) SATELLITE3 forces ( ) Vehicle names TARGET3 CRUISE3 targeting () seeker ( ) guidance ( ) control ( ) Communication bus combus [ ] intercept () aerodynamics ( ) propulsion ( ) forces ( ) newton ( ) intercept ( ) Modular structure seeker ( ) control ( ) guidance ( ) environment ( ) SCHEDULE targeting ( ) ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 5
- 9. Lab2 Classes Abstract base class Cadac • Cadac declares – Pointers of module-variable arrays Run-Time – Pure virtual functions for the executive processes Polymorphism – Pure virtual functions for the modules class Cadac { private: char name[CHARN]; //vehicle object name protected: //module-variable array of class 'Round3' CRUISE_2 Variable *round3; //module-variable array of class 'Cruise' Variable *cruise; //module-variable array of class 'Target' Variable *target; //module-variable array of class 'Satellite' Variable *satellite; class Variable public: { Cadac(){} private: virtual~Cadac(){}; char name[CHARN]; //executive functions char type[CHARN]; //pure virtual functions double rval; virtual void sizing_arrays()=0; int ival; .... Matrix VEC; //module functions Matrix MAT; //... pure virtual functions char def[CHARL]; }; char mod[CHARN]; char role[CHARN]; char out[CHARN]; public: //methods for initialization //methods for reading and loading ♣ }; MaSTech © 2009 Building Aerospace Simulations in C++ 6
- 10. Lab2 Classes Round3 inherits from Cadac • Spherical rotating Earth, 3 degrees of freedom • void Round3::environment(…) – ISO 62 standard atmosphere – Newton’s gravitational acceleration (inverse square law) • void Round3::newton(…) – Equations of motion are integrated in inertial coordinates – Conversion of input and output from/to geographic coordinates CRUISE_2 class Round3:public Cadac { protected: //declaring index arrays which identify module-variables for output public: Round3(); virtual~Round3(){}; //executive functions //... pure virtual functions //module functions //... pure virtual functions //virtual functions to be defined in this class virtual void def_environment(); virtual void init_environment(...); virtual void environment(...); virtual void def_newton(); virtual void init_newton(); virtual void newton(...); ♣ }; MaSTech © 2009 Building Aerospace Simulations in C++ 7
- 11. Lab2 Classes Cruise inherits from Round3 class Cruise:public Round3 • Bank-to-turn UAV { protected: void Cruise::aerodynamics(); //name of “CRUISE3” vehicle object char cruise3_name[CHARL]; Modules Drag polar //array pointers ... void Cruise::propulsion(...); public: Cruise(){}; Cruise(...); Turbojet virtual~Cruise(); void Cruise::forces(); //executive functions ... Aerodynamic and propulsive //module functions void Cruise::control(...); virtual void aerodynamics(); virtual void propulsion(...); CRUISE_2 virtual void forces(); Heading, flight path, bank angle, load virtual void control(...); virtual void guidance(); factor, altitude hold virtual void targeting(...); virtual void seeker(...); void Cruise::guidance(); virtual void intercept(...); Line, pro-nav, point, arc //functions of control module double control_heading(...); void Cruise::targeting(...); double control_flightpath(...); double control_bank(...); double control_load(...); Satellite targeting double control_lateral(...); double control_altitude(...); void Cruise::seeker(...); //functions of guidance module Line-of-sight seeker Matrix guidance_line(); Matrix guidance_pronav(); void Cruise::intercept(...); Matrix guidance_point(); double guidance_arc(); double guidance_spline(); Waypoint and target miss distance //functions of seeker module void seeker_grnd_ranges(...); //functions of targeting module void targeting_satellite(...); void targeting_grnd_ranges(...); ♣ }; MaSTech © 2009 Building Aerospace Simulations in C++ 8
- 12. Lab2 Classes Target inherits from Round3 CADAC class Target:public Round3 Hierarchy { protected: //name of “TARGET3” vehicle object char target3_name[CHARL]; //array pointers ... public: Target(){}; CRUISE_2 Target(...); virtual~Target(); //executive functions ... • Target over the round, rotating Earth //module function dummy returns virtual void def_aerodynamics(){}; void Target::forces(); ... //module functions active Compensating for Coriolis and virtual void forces(); centrifugal accelerations virtual void intercept(...); ♣ }; void Target::intercept(...); Setting target status (alive, hit, dead) MaSTech © 2009 Building Aerospace Simulations in C++ 9
- 13. Lab2 Classes Satellite inherits from Round3 class Satellite:public Round3 { protected: //name of ”SATELLITE3” vehicle object char satellite3_name[CHARL]; //array pointers ... public: Satellite(){}; CRUISE_2 Satellite(...); virtual~Satellite(); //executive functions ... //module function dummy returns • Target over the round, rotating Earth virtual void def_aerodynamics(){}; void Satellite::forces(); ... //module functions active Mass properties and optional thrusting virtual void forces(); void Satellite::seeker(...); virtual void seeker(...); ♣ Radar seeker (simplified) }; MaSTech © 2009 Building Aerospace Simulations in C++ 10
- 14. Lab2 Classes What you have learned • Class structure of the CADAC++ architecture • Cadac is an abstract base class • The class hierarchy declares the vehicle objects Cruise, Target, and Satellite • The vehicle objects are named CRUISE3, TARGET3, and SATELLITE3 in the ‘input.asc’ file • Modules are member functions (methods) of the derived classes • Use of access specifiers • Use of constructors and destructors ♣ SCHEDULE MaSTech © 2009 Building Aerospace Simulations in C++ 11
- 15. Building Aerospace Simulationsin C++ Lab2 Satellite Simulation … is the simplest simulation • Features of satellite simulation Lab Topics Simulation C++ Essentials • Class hierarchy of satellite simulation 1 CRUISE QuickStart • Equations of motions are derived from Classes 2 Satellite Simulation CRUISE_2 Newton’s Law 3 Modules Target Simulation CRUISE_3 • Inertial and Earth coordinate systems 4 Tables UAV Uncontrolled CRUISE_4 • Earth and geographic coordinate systems 5 Events UAV Controlled CRUISE_5 • Geographic and flight path coordinate system 6 Polymorphism CRUISE_6 • Geographic initialization UAV Navigation 7 ComBus CRUISE_7 • Solving the equations of motion UAV Homing Architectures • Circular orbiting satellite over the equator 8 CRUISE UAV Netcentric • What you have learned ♣ SCHEDULE Copyright © 2009 Modeling and Simulation Technologies
- 16. Lab2 Satellite Simulation Features of satellite simulation • 3 DoF, round, rotating Earth; • Coordinates: longitude, latitude, altitude • Newton’s equations solved in inertial coordinates • Conversion from geographic to inertial coordinates and vice versa • Propulsion is optional ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 2
- 17. Lab2 Satellite Simulation Class hierarchy of satellite simulation Abstract base class Cadac Virtual functions Derived class Round3 newton ( ) round3 [ ] environment ( ) Module- Derived class Variable arrays Satellite forces () satellite [ ] SATELLITE3 environment ( ) forces ( ) newton ( ) Modular structure ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 3
- 18. Lab2 Satellite Simulation Equations of motions are derived from Newton’s Law Zipfel, p. 261 * Newton’s Law mD I v IB = f a , p + mg Relationship of inertial and geographic velocities v IB = v E + Ω EI s BI B Matrix equations programmed in ‘newton’ module ( m [dvB / dt ]I = [T ]GI [T ]VG [ f a , p ]V + m [ g ]G I ) I Inertial coordinates [dsBI / dt ] = [v ] I I I B G Geographic coordinates * “Modeling and V Flight path coordinates Simulation of Aerospace Vehicle Dynamics”, AIAA Education Series, 2nd ♣ Edition, 2007 MaSTech © 2009 Building Aerospace Simulations in C++ 4
- 19. Lab2 Satellite Simulation Inertial and Earth coordinate systems • Inertial coordinate system 1I axis is aligned with the Vernal Equinox 3I axis is aligned with the spin axes of the Earth Zipfel, p. 71 • Angle Ξ is the hour angle • The transformation matrix of Earth wrt inertial coordinates is ⎡ cos Ξ sin Ξ 0⎤ [T ]EI = ⎢− sin Ξ cos Ξ 0⎥ ♣ ⎢ ⎥ ⎢ ⎣ 0 0 1⎥ ⎦ MaSTech © 2009 Building Aerospace Simulations in C++ 5
- 20. Lab2 Satellite Simulation Earth and geographic coordinate systems • Earth coordinate system 1E axis is at the intersection of the Greenwich Meridian and the equator 3E axis is aligned with the spin axis of the Earth Zipfel, p. 72 • Geographic coordinate system 1G axis points to the north pole 3G axis point to the center of the Earth • l longitude • λ latitude • TM sequences through two intermediate coordinate systems X and Y [T ]GE = [T (180o )]GY [T (90o − λ )]YX [T (l )]XE • The TM of geographic wrt Earth coordinates is ⎡ − sin λ cos l − sin λ sin l cos λ ⎤ [T ]GE = ⎢ − sin l cos l 0 ⎥♣ ⎢ ⎥ ⎢− cos λ cos l − cos λ sin l − sin λ ⎥ ⎣ ⎦ MaSTech © 2009 Building Aerospace Simulations in C++ 6
- 21. Lab2 Satellite Simulation Geographic and flight path coordinate system • Geographic coordinate system 1G axis points to the north pole 1V 3G axis point to the center of the Earth • Flight path coordinate system Zipfel, p. 80 1G 2V 2G X 1V axis parallel and in the direction of the 2X 1 velocity vector 2V axis is horizontal and points to the right 3V 3V axis point “down” • χ heading angle (chi) X 3 = 3G • γ flight-path angle • The TM of flight path wrt geographic coordinates is [T ]VG = [T (γ )]VX [T ( χ )] XG ⎡cos γ 0 − sin γ ⎤ ⎡ cos χ sin χ 0⎤ ⎡cos γ cos χ cos γ sin χ − sin γ ⎤ [T ]VG =⎢ 0 1 0 ⎥ ⎢− sin χ cos χ 0⎥ = ⎢ − sin χ cos χ 0 ⎥ ♣ ⎢ ⎥⎢ ⎥ ⎢ ⎥ ⎢ sin γ ⎣ 0 cos γ ⎥ ⎣ 0 ⎦⎢ 0 1⎥ ⎢ sin γ cos χ ⎦ ⎣ sin γ sin χ cos γ ⎥⎦ MaSTech © 2009 Building Aerospace Simulations in C++ 7
- 22. Lab2 Satellite Simulation Geographic initialization • Geographic initialization converted to inertial position and velocity CRUISE_2 Implemented in: void Round3::init_newton() E Geographic speed | vB | χ Heading angle γ Flight path angle | v B | , χ , γ , l, λ , h E l Longitude λ Latitude h Altitude E | vB | [T ]GE = cadtge( l, λ) [ s BI ] I [sBI ]E = [T ]EG[sBI ]G Inertial position [vB ]G = cart_ from_ pol | vB |, χ, γ E E ( ) [v B ] I I Inertial velocity [T ] = [E] IE GV [T ]IG = [T ]IE[T ]EG [T ] T.M. of geographic wrt flight path coor. [vB ]I = [T ]IG[vB ]G + [ΩEI ]I [sBI ]I I E [T ] IG T.M. of inertial wrt geographic coor. VG [T ] = mat2tr( χ, γ ) [T ]GV = [T ]VG ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 8
- 23. Lab2 Satellite Simulation Solving the equations of motion • Integrating inertial states and converting them to geographic output CRUISE_2 Implemented in: void Round3::newton(double int_step) [ f sp ]V Propulsive specific force ( [ dvB / dt ]I = [T ]IG [T ]GV [ f sp ]V + [ g ]G I ) [ dsBI / dt ]I = [ vB ]I I E | vB | [T ] EI = cadtei (time) χ γ [ s BI ] E = [T ] EI [ s BI ] I (l , λ , h ) = cadsph ([ s BI ]E ) l λ [T ]GE = cadtge (l , λ ) h [T ]GI = [T ]GE [T ] EI ( [v B ]G = [T ]GI [v B ] I − [Ω EI ] I [ s BI ] I E I ) ( | v B |, χ , γ E ) = pol _ from _ cart ( [v B ]G E ) [T ] VG = mat 2tr ( χ , γ ) [T ]GV = [T ]VG ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 9
- 24. Lab2 Satellite Simulation Circular orbiting satellite over the equator Input alt 300000 //Vehicle altitude - m module newton psivgx 90 //Vehicle heading angle - deg module newton CRUISE_2 thtvgx 0 //Vehicle flight path angle - deg module newton dvbe 7243.2 //Vehicle speed - m/s module newton Satellite inertial speed G×M⊕ | v B |= I R⊕ + alt Earth circumferential speed at equator | Δv |= (R⊕ + alt )ω EI ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 10
- 25. Lab2 Satellite Simulation What you have learned • The core of the simulation, i.e., the ‘newton’ module, simulates satellite orbits • Key coordinate systems – Inertial, Earth, geographic and flight path angle • Newton’s equations of motion are integrated in inertial coordinates • Input/output conversion are from geographic to inertial coordinates and back ♣ HandsOn2 SCHEDULE MaSTech © 2009 Building Aerospace Simulations in C++ 11
- 26. Building Aerospace Simulationsin C++ Lab2 HandsOn2 … let’s start with a simple class structure and simulation • HandsOn2_1 Duplicate the satellite trajectory • HandsOn2_2 Add the module ‘seeker’ to the ‘Satellite’ class • HandsOn2_3 Find the constructor and destructor of the ‘Satellite’ class SCHEDULE • HandsOn2_4 Raise the satellite orbit by thrusting Copyright © 2009 Modeling and Simulation Technologies
- 27. HandsOn2 HandsOn2_1 Duplicate the satellite trajectory 1. Load the CRUISE_2 project and run the test case with input file ‘input2_1.asc’ 2. Plot the trajectory with the KPLOT-GLOBE program and thus duplicate the circular satellite trajectory over the equator, as shown in Slide 10 of ‘Lab2 Satellite Simulation’ 3. What is the deviation in percent from the starting altitude? 4. Reduce and increase the integration step size by an order of magnitude Result2_1 - How does the integration step size effect the accuracy? ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 2
- 28. HandsOn2 HandsOn2_2 Add the module ‘seeker’ to the ‘Satellite’ class • For future usage, the ‘Satellite’ class needs a ‘seeker’ module. Provide two skeleton member functions ‘def_seeker()’ and ‘seeker(…)’ as place holders in the file ‘satellite_modules.cpp’ 1. In file ‘satellite_modules.cpp’ add the skeleton of ‘def_seeker()’ and ‘seeker(…)’ following the example of functions ‘def_forces()’ and ‘forces()’, without code inside the function scopes 2. Declare the two new functions in the class ‘Satellite’ of the header file ‘class_hierarchy.hpp’ Result2_2 3. Check your modifications by recompiling ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 3
- 29. HandsOn2 HandsOn2_3 Find the constructor and destructor of the ‘Satellite’ class 1. Locate the constructor of the ‘Satellite’ class What is the purpose of the parameters? What memory allocations occur? 2. Locate the destructor of the ‘Satellite’ class Result2_3 What action does the destructor perform? ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 4
- 30. HandsOn2 HandsOn2_4 Raise the satellite orbit by thrusting • In the ‘force’ module a constant thrust force can be applied to the satellite 1. Augment the input file ‘input2_1.asc’ with the satellite thrust variable 2. Determine what thrust is required to increase the satellite altitude by 100 km after one orbit Result2_4 3. Make a plot with KPLOT-GLOBE ♣ SCHEDULE MaSTech © 2009 Building Aerospace Simulations in C++ 5
- 31. Building Aerospace Simulationsin C++ Lab2 Result2 … let’s start with a simple class structure and simulation • Result2_1 Duplicate the satellite trajectory • Result2_2 Add the module ‘seeker’ to the Satellite class • Result2_3 Find the constructor and destructor of the ‘Satellite’ class SCHEDULE • Result2_4 Raise the satellite orbit by thrusting Copyright © 2009 Modeling and Simulation Technologies
- 32. Result2 Result2_1 Duplicate the satellite trajectory 1 & 2 Self explanatory 3. The deviation form the starting altitude is 0.33% 4. Integration step size - increased by order of magnitude the error is 3.3% - decreased by order of magnitude the error is 0.031% MaSTech © 2009 Building Aerospace Simulations in C++ 2
- 33. Result2 Result2_2 Add the module ‘seeker’ to the Satellite class CRUISE_2 • For the implementation of the two member functions ‘def_seeker()’ and ‘seeker(…)’, look into the file ‘satellite_modules.cpp’ and ‘class_hierarchy.hpp’ of the CRUISE simulation ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 3
- 34. Result2 Result2_3 Find the constructor and destructor of the ‘Satellite’ class CRUISE_2 1. The constructor is located in file ‘class_functions.cpp’ The parameter list consists of the pointer to the module array and the size of the module array Dynamic memory allocation is made for Module variable array ‘satellite’ Combus index arrays ‘round3_com_ind’ and ‘com_satellite3’ 2. The destructor is located in file ‘class_functions.cpp’ It releases the dynamic memory allocated of the ‘Satellite’ members ‘satellite’, ‘round3’, ‘round3_com_ind,; ‘satellite_com_ind’, ‘com_satellite3’ MaSTech © 2009 Building Aerospace Simulations in C++ 4
- 35. Result2 Result2_4 Raise the satellite orbit by thrusting CRUISE_2 Required thrust to raise satellite by 100km SCHEDULE sat_thrust = 1.03 N MaSTech © 2009 Building Aerospace Simulations in C++ 5
- 36. Building Aerospace Simulationsin C++ Lab3 Modules … model the vehicle components • Modules form the core of the simulation Lab Topics Simulation • Module-variables interface between modules C++ Essentials 1 QuickStart CRUISE • Three functions compose the ‘newton’ module 2 Classes CRUISE_2 • Modules are called every integration cycle Satellite Simulation Modules • Module-variables are of type Variable 3 CRUISE_3 Target Simulation • Example code of module ‘newton’ Tables 4 UAV Uncontrolled CRUISE_4 • How to build a module 5 Events CRUISE_5 • Matrix utility operations UAV Controlled Polymorphism • Matrix class and methods 6 CRUISE_6 UAV Navigation • More examples of Matrix methods ComBus 7 CRUISE_7 UAV Homing • Utility functions of class Matrix SCHEDULE Architectures 8 UAV Netcentric CRUISE • What you have learned ♣ SCHEDULE Copyright © 2009 Modeling and Simulation Technologies
- 37. Lab3 Modules Modules form the core of the simulation • Modules are public functions (methods) of the classes Round3, Cruise, Satellite and Target • The structure Module declares the type of the elements in the ‘module_list’ array CRUISE_3 • The module list and calling sequence is established in the ‘input.asc’ file • Coding of the modules is greatly simplified by matrix equations • The class Matrix enables the straightforward writing of matrix equations ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 2
- 38. Lab3 Modules Module-variables interface between modules • CADAC’s modular structure mirrors the hardware components of an aerospace vehicle – A module is a model of a vehicle component • Examples: aerodynamics, propulsion, actuator, guidance, control,… – Each module consists of at least two functions and possibly four: • def_module(), init_module(), module(), term_module() • The calling order of the module is controlled by the input file Module-Variable • Data between modules is transferred by module-variables Arrays – Module-variables, being the only allowed interface, are strictly controlled – Each vehicle object reserves protected arrays for its module-variables – There is a one-to-one relationship between the module-variable name and the array location CRUISE_3 – The file ‘doc.asc’ documents all module-variables • Module-variables can only be of type int, double, 3x1 vector, and 3x3 matrix • Inside a module – Module-variables are localized as input from other modules – Computations create new module-variables – These are loaded onto the object’s array for output ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 3
- 39. Lab3 Modules Three functions compose the ‘newton’ module void Round3::def_newton() Definition of module-variables used in this module void Round3::init_newton () Initial calculations void Round3::newton(double int_step) Integrations and time-phased calculations Integration loop ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 4
- 40. Lab3 Modules Modules are called every integration cycle Calling sequence established in input.asc MODULES environment def,init,exec struct Module aerodynamics def,exec { propulsion def,init,exec string name; forces def,exec string definition; newton def,init,exec string initialization; targeting def,exec string execution; seeker def,exec string termination; guidance def,exec }; control def,exec intercept def,exec END Loading modules into module_list void order_modules(fstream &input,int &num,Module *module_list) Module calling //Vehicle’s constructor calls module to define module-variables if((module_list[j].name==“newton")&&(module_list[j].definition=="def")) def_newton(); //Module is initialized in ‘main()’ if((module_list[j].name==“newton")&&(module_list[j].initialization=="init")) vehicle_list[i]->init_newton(); //Every integration step, module is called in ‘execute(…)’ if(module_list[j].name==“newton") vehicle_list[i]->newton(int_step); ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 5
- 41. Lab3 Modules Module-variables are of type Variable class Variable { Defining module-variables in void Round3::def_newton() private: char name[CHARN]; round3[19].init("lonx",0,"Vehicle longitude - deg","newton","diag","scrn,plot,com"); char type[CHARN]; double rval; round3[20].init("latx",0,"Vehicle latitude - deg","newton","diag","scrn,plot,com"); int ival; Matrix VEC; round3[21].init("alt",0,"Vehicle altitude - m","newton","out","scrn,plot,com"); Matrix MAT; char def[CHARL]; Documenting module-variables in doc.asc char mod[CHARN]; char role[CHARN]; char out[CHARN]; Round3 Module-Variable Array public: methods to initialize --------------------------------------------------------------------------------------------------------------------- |LOC| NAME | DEFINITION | methods to read OUTPUT MODULE | PURPOSE | and load| --------------------------------------------------------------------------------------------------------------------- }; ………………………………………………………… 19 lonx Vehicle longitude - deg newton diag scrn,plot,com 20 latx Vehicle latitude - deg newton diag scrn,plot,com 21 alt Vehicle altitude - m newton out scrn,plot,com ………………………………………………………… Using module-variables void Round3::newton(double int_step) { //localizing module-variables //input from other modules double time=round3[0].real(); Matrix FSPV=round3[10].vec(); ... //----------------------------------------- ... computations ... //------------------------------------------- //loading module-variables //state variables round3[35].gets_vec(SBII); round3[36].gets_vec(VBII); ♣ ... } MaSTech © 2009 Building Aerospace Simulations in C++ 6
- 42. Lab3 Modules Example code of module ‘newton’ CRUISE_3 void Round3::def_newton() { name, value, definition, module, type, out to: screen, plot file, combus Definition of //Definition of module-variables module-variables round3[19].init("lonx",0,"Vehicle longitude-deg","newton","diag","scrn,plot,com"); round3[20].init("latx",0,"Vehicle latitude-deg","newton","diag","scrn,plot,com"); in array ‘round3[ ]’, round3[21].init("alt",0,"Vehicle altitude-m","newton","out","scrn,plot,com"); a member of class ... ‘Round3’ }void Round3::init_newton() { ........................ } void Round3::newton(double int_step) { //localizing module-variables Getting module- //input from other modules double time=round3[0].real(); variables from Matrix FSPV=round3[10].vec(); ‘round3[ ]’ array double grav=round3[11].real(); Matrix WEII=round3[27].mat(); //state variables Matrix SBII=round3[35].vec(); Matrix VBII=round3[36].vec(); Matrix ABII=round3[37].vec(); ... //------------------------------------------------------------------------- //building gravitational vector in geographic coordinates GRAV.assign_loc(2,0,grav); //integrating inertial state variables Computations ABII_NEW=TIG*((TGV*FSPV)+GRAV); VBII_NEW=integrate(ABII_NEW,ABII,VBII,int_step); SBII=integrate(VBII_NEW,VBII,SBII,int_step); ABII=ABII_NEW; VBII=VBII_NEW; ... //------------------------------------------------------------------------- //loading module-variables Loading module- //state variables variables onto round3[35].gets_vec(SBII); round3[36].gets_vec(VBII); ‘round3[ ]’ array round3[37].gets_vec(ABII); ♣ ... } MaSTech © 2009 Building Aerospace Simulations in C++ 7
- 43. Lab3 Modules How to build a module 1. Start with sample module as template Example: Newton Module 2. Reserve contiguous slots in the module-array 3. In ‘def_module’ categorize module-variables as ///////////////////////////////////////////////// //Definition of newton module-variables "data" input data values //Member function of class 'Round3' "init" initialized in init_module //Module-variable locations are assigned // to round3[17-39] "state" state variables for integration //000624 Created by Michael Chiaramonte "out" output to other modules ///////////////////////////////////////////////// "diag" diagnostic, not used by other modules void Round3::def_newton() { "save" value saved for next cycle 4. In ‘module’ localize module-variables by category //Definition of module-variables round3[19].init("lonx",0,"Vehicle longitude-d //input data round3[20].init("latx",0,"Vehicle latitude-deg //restore saved values round3[21].init("alt",0,"Vehicle altitude-m"," //state variables }void Round3::init_newton() //input from other modules { 5. Insert computations ........................ } 6. In ‘module’ load module-variables by category void Round3::newton(double int_step) CRUISE_3 //state variables { //saving values //localizing module-variables //input from other modules //output to other modules double time=round3[0].real(); //diagnostics Matrix FSPV=round3[10].vec(); double grav=round3[11].real(); 7. Incorporate new module into simulation frame Matrix WEII=round3[27].mat(); //state variables Definition module is called once, before ‘input.asc’ Matrix SBII=round3[35].vec(); Matrix VBII=round3[36].vec(); Defines all module-variables Matrix ABII=round3[37].vec(); ... Directs variables to output streams //------------------------------------------ Initialization module is called once, after ‘input.asc’ //building gravitational vector in geographic GRAV.assign_loc(2,0,grav); Executes initial calculations Module is called once every integration step //integrating inertial state variables ABII_NEW=TIG*((TGV*FSPV)+GRAV); Localizes module-variables VBII_NEW=integrate(ABII_NEW,ABII,VBII,int_step); Executes computations every integration step SBII=integrate(VBII_NEW,VBII,SBII,int_step); ABII=ABII_NEW; Integrates state variables VBII=VBII_NEW; ... Calls other subordinate functions //-------------------------------------------- Calls utility subroutines //loading module-variables //state variables Performs table look-up round3[35].gets_vec(SBII); Loads module-variables round3[36].gets_vec(VBII); round3[37].gets_vec(ABII); Watch out ... Initialize all local variables } Don’t call other module’s subordinate functions ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 8
- 44. Lab3 Modules Matrix utility operations • Source code should be programmed in matrices as much as possible – Compact code – Avoids errors • Requirements of flight simulations – Mostly 3x1 and 3x3 matrices, some of higher dimensions (Kalman filters) – Elements of matrices are of type double • Class Matrix instantiate a pointer to the matrix *pbody and initializes the elements to zero • Examples from module Target::forces() CRUISE_3 //Coriolis acceleration in V-coordinates WEIG=TGE*WEII*TEG; CORIO_V=TVG*WEIG*VBEG*2; //centrifugal acceleration in V-coordinates CENTR_V=TVG*WEIG*WEIG*TGI*SBII; • Special features – All matrix manipulations are carried out in pointer arithmetic – Creating a matrix returns *this of the initialized matrix – Usage of copy constructor for the matrix assignment operator – Overloaded offset operator [] ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 9
- 45. Lab3 Modules Matrix class and methods class Matrix { •Matrix class is global in scope private: //number of rows • Private methods declare size and int num_row; //number of columns pointer of array int num_col; //total number of elements • Public methods are the int num_elem; //pointer to array constructors/destructor and utility double *pbody; public: functions //default constructors Matrix(); CRUISE_3 //overloaded constructor Matrix(int row_size,int col_size); //copy constructor Matrix(const Matrix &MAT); //destructor ~Matrix(); //printing matrix array to console //////////////////////////////////////////// //Absolute value of vector void print(); //Example: value = VEC.absolute(); //Returns absolute value of a vector VEC //////////////////////////////////////////// //Example: value=VEC.absolute(); double Matrix::absolute() double absolute(); { … }; double ret=0; for(int i=0;i<num_elem;i++) ret+=(*(pbody+i))*(*(pbody+i)); ret=sqrt(ret); return ret; } ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 10
- 46. Lab3 Modules More examples of Matrix methods /////////////////////////////////////////////////////////////////////////////// //Returns the value at offset-row 'r‘, offset-col 'c' of MAT //Example: value = MAT.get_loc(2,1); (3rd row, 2nd column) ////////////////////////////////////////////////////////////////////////////// double Matrix::get_loc(const int &r,const int &c) { if((r<num_row)&&(c<num_col)) return *(pbody+r*num_col+c); else {cout<<"*** Error: invalid matrix loc. 'Matrix::get_loc()' *** ";exit(1);} } /////////////////////////////////////////////////////////////////////////////// //Builds a square identity matrix of object 'Matrix MAT' //Example: MAT.identity(); /////////////////////////////////////////////////////////////////////////////// Matrix & Matrix::identity() { if (num_row==num_col) { for(int r=0;r<num_row;r++) *(pbody+r*num_row+r)=1; } else {cout<<"*** Error: matrix not square 'Matrix::identiy()'*** ";exit(1);} return *this; } ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 11
- 47. Lab3 Modules Utility functions of class Matrix Member functions void print(); double absolute(); Matrix adjoint(); void assign_loc(…) Overloaded operators Matrix & build_mat33(…); Matrix & cart_from_pol(…) bool operator!=(const Matrix &B); Matrix col_vec(const int &col); Matrix operator*(const double &b); double determinant(); Matrix operator*(const Matrix &B); Matrix diamat_vec(); Matrix diavec_mat(); Matrix & operator*=(const double &b); void dimension(int row,int col); Matrix & operator*=(const Matrix &B); Matrix ellipse(); CRUISE_3 Matrix operator+(const double &b); int get_cols(); Matrix operator+(const Matrix &B); int get_index(const int &row,const int &col); double get_loc(const int &r,const int &c); Matrix & operator+=(const double &b); double * get_pbody(); Matrix & operator+=(const Matrix &B); int get_rows(); Matrix operator-(const double &b); Matrix & identity(); Matrix operator-(const Matrix &B); Matrix inverse(); Matrix mat33_vec9(); Matrix & operator-=(const double &b); Matrix & ones(); Matrix & operator-=(const Matrix &B); bool operator!=(const Matrix &B); Matrix &operator=(const Matrix &B); Matrix pol_from_cart(); Matrix row_vec(const int &row); bool operator==(const Matrix &B); Matrix skew_sym(); double & operator [](const int &r); Matrix sub_matrix(const int &row, const int &col); double operator^(const Matrix &B); Matrix trans(); Matrix operator~(); Matrix univec3(); Matrix & zero(); Matrix vec9_mat33(); ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 12
- 48. Lab3 Modules What you have learned • Modules mirror vehicle components • Module loading and calling sequence is established in the input file • Communication between modules is only by module-variables • The value of module-variables is stored in protected arrays of the vehicle classes • Computations in modules are carried out in matrix form, where applicable SCHEDULE • Matrix manipulations use methods of the class Matrix ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 13
- 49. Building Aerospace Simulationsin C++ Lab3 Target Simulation … simulates vehicles moving on the ground Lab Topics Simulation 1 C++ Essentials CRUISE • Features of target simulation QuickStart Classes • Class hierarchy of target simulation 2 CRUISE_2 Satellite Simulation Modules • Equations of motions are compensated 3 CRUISE_3 Target Simulation • Vehicles on the Earth’s surface experience Tables 4 UAV Uncontrolled CRUISE_4 apparent forces 5 Events UAV Controlled CRUISE_5 • Calculating the acceleration compensation 6 Polymorphism UAV Navigation CRUISE_6 • Straight target trajectory 7 ComBus CRUISE_7 • What you have learned ♣ UAV Homing Architectures 8 CRUISE UAV Netcentric SCHEDULE Copyright © 2009 Modeling and Simulation Technologies
- 50. Lab3 Target Simulation Features of target simulation • Targets move on the surface of the round, rotating Earth – Fixed – Translating – Accelerating • Coordinates: longitude, latitude, altitude • Newton’s equations are compensated with apparent forces ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 2
- 51. Lab3 Target Simulation Class hierarchy of target simulation CRUISE_3 Abstract base class Cadac Virtual functions Derived class Round3 newton ( ) environment ( ) round3 [ ] Module- Derived class Variable arrays Target forces( ) target [ ] intercept ( ) TARGET3 environment ( ) forces ( ) newton ( ) intercept ( ) Modular structure ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 3
- 52. Lab3 Target Simulation Equations of motions are compensated • Newton’s Law governs the motion of the target • Compensating forces are applied to constrain the target to the surface of the Earth Newton’s Law with compensation ma comp mD I v I = ma comp + mg B Matrix equations programmed in ‘newton’ module I Inertial coordinates ( [dv B / dt ] I = [T ]GI [T ]VG [acomp ]V + [ g ]G I ) G Geographic coordinates V Flight path coordinates ♣ MaSTech © 2009 Building Aerospace Simulations in C++ 4
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