Framework design for high-fidelity hardware-in- the-loop ... 03/Archivo 0… · I. S. Husain...

Framework design for high-fidelity hardware-in-the-loop LEO satellite simulations

I. S. Husain Cerruti – M. España - IAA-LA2-03-04

2nd IAA Latin American Symposium on Small Satellites

11–16 Nov. 2019, Buenos Aires, Argentina

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Santiago Husain Cerruti – Martín España12 November 2019





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Presentation outline

Motivation

Testbed architecture

Main class diagrams

Observers concept and communication with Spirent GNSS simulator

Technologies used and results

Conclusions and way forward





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Why do we need a satellite testbed?





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Advanced GNC concepts, especially for Distributed

Space Systems





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Space Systems

Develop autonomous control strategies (no

ground-station)





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Space Systems

Develop new hardware: GNSS receivers, on-board cameras, RF ranging system, Comms.


ground-station)





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Space Systems



ground-station)

Test & develop on-board computers





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Space Systems



ground-station)


Initial technology demonstration, especially

for small satellites





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Space Systems



ground-station)


Initial technology demonstration, especially

for small satellites

Develop satellite modules in a component-based fashion





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What challenges do we face?





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Initial software design:MatLab’s procedural

programming languageGood to set initial architectureFunctions calling each otherHighly coupled modulesNo clear responsibilities





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Initial software design:MatLab’s procedural

programming languageGood to set initial architectureFunctions calling each otherHighly coupled modulesNo clear responsibilities

Challenges to face: Many interacting components Diverse ways of communication Changes in HW & SW specifications Scalability





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Many layers of complexity called for a systematic approach Software Engineering Design Principles Software Engineering Tools Incremental development from simple to complex Modularity through well defined interfaces





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How do we design the testbed?





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How do we design the testbed? Define hardware components





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Simulation Server

Trajectory Generator

Ground-truth data





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Simulation Server


GNSS RF Simulator

SPIRENT SimGen : OMG<<TCP/IP>>

True TimeTrue Satellite Position, Vel, Acc.

Output Magnitudes Generator (OMG) software component

SPIRENT GSS 8000





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Simulation Server


Spacecraft

GNSS Receiver

NMG

GNSS RF Simulator


<<physical connection>>

True GNSS RF signalL1/L2/L5E1/E5ab

Navigation Measurements Generator (NMG) software

component





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Simulation Server

Trajectory GeneratorActuator Model

Spacecraft

OBC

GNSS Receiver

NMG

GNSS RF Simulator



<<TCP/IP>>

Control VectorTime of Application

Navigation solution

Delta-V





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Simulation Server


Accelerometer Simulator

OMG

Spacecraft

OBC

GNSS ReceiverIMU

NMG NMG

GNSS RF Simulator



<<TCP/IP>>





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Simulation Server



OMG

Gyroscope Simulator

OMG

Spacecraft

OBC

GNSS ReceiverIMU

NMG NMG

GNSS RF Simulator



<<TCP/IP>>





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What do we solve with this design approach?





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Many interacting components Modularization





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Diverse ways of communication Common interfaces





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Change in HW & SW specifications? Just adhere to the rules defined

by the interfaces





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Specialist develop their own componentsPlug in - Plug outIncrease development

speed and cycles



Change in HW & SW specifications? Just adhere to the rules defined

by the interfaces






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How do we design the software components?





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Object-oriented programming Best suited for simulation software






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Use Unified Modeling Language (UML) Convey concepts rapidly using diagrams






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Model the high-fidelity trajectory generator





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+ updateState()

+ getVelAndAccAt()

Spacecraft

Model the high-fidelity trajectory generator





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+ updateState()

+ getVelAndAccAt()

Spacecraft

+ updateState()

Integrator

+ sampleAttachedObjectAt(s : State)

Perturbation

+ getCurrentMass()

+ getAcceleration()

+ getAccumulatedDeltaV()

Actuator

*

*

A Spacecraft is affected by





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+ updateState()

+ getVelAndAccAt()

Spacecraft

+ updateState()

Integrator


Perturbation

+ getCurrentMass()

+ getAcceleration()


Actuator

*

*

A Spacecraft has





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+ updateState()

+ getVelAndAccAt()

Spacecraft

+ updateState()

Integrator


Perturbation

+ getCurrentMass()

+ getAcceleration()


Actuator

*

*

A Spacecraft needs





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+ updateState()

+ getVelAndAccAt()

Spacecraft

+ updateState()

Integrator


Perturbation

+ getCurrentMass()

+ getAcceleration()


Actuator

*

*





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+ updateState()

+ getVelAndAccAt()

Spacecraft

+ currentState()

+ setInitialState()

+ updateState()

Component

+ updateState()

Integrator


Perturbation

+ getCurrentMass()

+ getAcceleration()


Actuator

+ time()

+ acceleration()

+ velocity()

+ position()

State

*

*

*

Extract common interface





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+ updateState()

+ getVelAndAccAt()

Spacecraft

+ currentState()

+ setInitialState()

+ updateState()

Component

+ updateState()

Integrator


Perturbation

+ getCurrentMass()

+ getAcceleration()


Actuator

+ time()

+ acceleration()

+ velocity()

+ position()

State

*

*

*





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+ updateState()

+ getVelAndAccAt()

Spacecraft

+ currentState()

+ setInitialState()

+ updateState()

Component

+ updateState()

Integrator


Perturbation

+ getCurrentMass()

+ getAcceleration()


Actuator

+ time()

+ acceleration()

+ velocity()

+ position()

State

ReferenceSystem

*

*

*





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+ trigger()

+ run()

Controller

+ update() : void

Scenario

+ updateState()

+ getVelAndAccAt()

Spacecraft

+ currentState()

+ setInitialState()

+ updateState()

Component

+ updateState()

Integrator


Perturbation

+ getCurrentMass()

+ getAcceleration()


Actuator

+ time()

+ acceleration()

+ velocity()

+ position()

State

ReferenceSystem

*

*

*

1*

Extract common interface





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+ trigger()

+ run()

Controller

+ update() : void

Scenario

+ updateState()

+ getVelAndAccAt()

Spacecraft

+ currentState()

+ setInitialState()

+ updateState()

Component

+ updateState()

Integrator


Perturbation

+ getCurrentMass()

+ getAcceleration()


Actuator

+ time()

+ acceleration()

+ velocity()

+ position()

State

ReferenceSystem

*

*

*

1*





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+ trigger()

+ run()

Controller

+ update() : void

Scenario

+ updateState()

+ getVelAndAccAt()

Spacecraft

+ currentState()

+ setInitialState()

+ updateState()

Component

+ updateState()

Integrator


Perturbation

+ getCurrentMass()

+ getAcceleration()


Actuator

+ time()

+ acceleration()

+ velocity()

+ position()

State

ReferenceSystem

*

*

*

High-Fidelity


1*

Independent components





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RungeKutta

BullirshStoer

AdaptiveStep

AtmosphericDrag

SRP

ContinuousThruster

PulsedThruster

IAU76/FK5ITRFHill UTCGPS Time

Perturbation

Albedo

Integrator

Actuator

ReferenceSystem

Earth Gravity

Third-body gravity





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Modules communication





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Component-based design conceptClasses must minimize coupling

Interfaces

General communication mechanisms

Solved through Observer design pattern (DP)

DP: solution to a common recurring problem





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+ update()

<<interface>>

Observer

+ sendMeasurement()

+ generateMeasurement()

+ storeDataPacket()

<<interface>>

OutputMeasurementGenerator

+ sendUDPDatagram()

SimGenSocket

+ generateUDPDatagram()

SPIRENT_GNSS_Simulator





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+ notifyObservers()

+ subscribeObserver()

<<interface>>

ObservedSubject

+ update()

<<interface>>

Observer

+ sendMeasurement()


+ storeDataPacket()

<<interface>>


*

+ sendUDPDatagram()

SimGenSocket



*

Integrator





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Preliminary validationsLEO at 700km, i=98°, circular orbit

1 orbital period simulation.

JGM-3 70x70

RK-4 100 ms step

IAU76/FK5 - J2000 ECI reference frame

Developed a MatLab interface to control STK and automate tests.P-V-A differences and absolute values with

respect to STK/HPOP0,4 mm position difference

0,6 um/s velocity difference

0,4 nm/s^2 acceleration difference





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Technologies used

C++ 17

Eigen Linear Algebra Library

C++ Boost Libraries

YAML

Standards of Fundamental Astronomy Library - SOFA

Automate simulations through any scripting language





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Conclusions and way forwardDeveloped a framework to implement a high-fidelity spacecraft testbed with

real-time and hardware-in-the-loop capabilities





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Developed modules can be used in other projects.





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Test autonomous GNC algorithms developed by different specialists.





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Allows real-time and multi-CPU simulations.





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Allows real-time and multi-CPU simulations.

Framework not only applied to LEO satellite simulations, it’s flexible and generally applicable to any space vehicle simulation: Simulate satellite injectors

Servicing non-cooperative satellite simulation

Simulate distributed satellite platforms





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Questions?





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References1. J. Relloso - A. Laudari - J. Lavirgen - M. España, Hardware in the Loop Test Bed for Distributed Satellite

Platform Navigation and Orbit Control, 2nd IAA Latin American Symposium on Small Satellites, IAA-LA2-03-03, Buenos Aires, Argentina (2019)

2. R. C. Martin, Agile software development: principles, patterns, and practices, Pearson Education, Inc. (2003)3. I. S. Husain - M. España, Generation of GNSS Observables for LEO Satellites Using High-Fidelity Models, 1st

IAA Latin American Symposium on Small Satellites, IAA-LA-14-04, Buenos Aires, Argentina (2017)4. M. Page-Jones, Fundamentals of Object-Oriented Design in UML, Addison-Wesley (2000)5. B. Meyer, Object-Oriented Software Construction, 2nd edn., Prentice Hall (1997)6. E. Gamma, et al., Design Patterns: elements of reusable object-oriented software, Addison-Wesley

professional computing series (1994)7. S. D’Amico, Autonomous Formation Flying in Low Earth Orbit, Technische Universiteit Delft (2010)8. S. D’Amico, et al., GPS-Based Real-Time Navigation for the PRISMA Formation Flying Mission, NAVITEC’2006,

11-13 December 2006, Noordwijk (2006)





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Authors contact information

Ignacio Santiago Husain Cerruti EE Student at the School of Engineering of the University of Buenos Aires

[email protected]

Martín EspañaSenior researcher at CONAE

[email protected]

+54 11 4331 0074

mailto:[email protected]

mailto:[email protected]





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Back-up slides





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Simulation Server



OMG

Sky Imaging Simulator

OMG

Gyroscope Simulator

OMG

Spacecraft

OBC

Star TrackerGNSS Receiver IMU

NMGNMG NMG

GNSS RF Simulator



<<TCP/IP>>





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+ trigger()

+ run()

Controller

+ update() : void

Scenario

+ updateState()

+ getVelAndAccAt()

Spacecraft + currentState()

+ setInitialState()

+ updateState()

Component

+ updateState()

Integrator


Perturbation

+ getCurrentMass()

+ getAcceleration()


Actuator

+ time()

+ acceleration()

+ velocity()

+ position()

State ReferenceSystem

*

*

*

High-Fidelity

Model

May be triggered

by PPS signal

coming from

SPIRENT GNSS

signal simulator.

1*





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RungeKutta

BullirshStoer

AdaptiveStep

AtmosphericDrag

SRP

ContinuousThruster

PulsedThruster

IAU76/FK5ITRFHill UTCGPS Time

Perturbation

Albedo

Integrator

Actuator

ReferenceSystem

Earth Gravity

Third-body gravity





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Synchronization of the testbed?





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× Initial design in MatLab was not adequate× Depended on a particular calling sequence of functions× The integrator was in charge of doing it

× No loose-coupling and mixed responsibilities





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Controller class

× Initial design in MatLab was not adequate× Depended on a particular calling sequence of functions× The integrator was in charge of doing it

× No loose-coupling and mixed responsibilities





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Simulation Server



OMG

Sky Imaging Simulator

OMG

Gyroscope Simulator

OMG

Spacecraft

OBC

Star TrackerGNSS ReceiverIMU

NMGNMG NMG

GNSS RF Simulator



<<TCP/IP>>

How do we synchronize the testbed?

Precise Pulse-per-second (PPS) signal





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+ trigger()

+ run()

Controller

+ update() : void

Scenario

+ updateState()

+ getVelAndAccAt()

Spacecraft

+ currentState()

+ setInitialState()

+ updateState()

Component

+ updateState()

Integrator


Perturbation

+ getCurrentMass()

+ getAcceleration()


Actuator

+ time()

+ acceleration()

+ velocity()

+ position()

State

ReferenceSystem

*

*

*

High-Fidelity


May be

triggered by

PPS signal

coming from

SPIRENT

GNSS signal

simulator.

1*

How do we synchronize the testbed?

Synchronization





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Modules communicationComponent-based design conceptClasses must minimize coupling

Interfaces

General communication mechanisms

Solved through Observer design pattern (DP)

DP: solution to a common recurring problem

Component

+ notifyObservers()


<<interface>>

ObservedSubject

+ update()

<<interface>>

Observer

*

AnotherComponent





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+ notifyObservers()


<<interface>>

ObservedSubject

+ update()

<<interface>>

Observer

+ sendMeasurement()


+ storeDataPacket()

<<interface>>


*

GNSSreceiver

<<interface>>

NavigationMeasurementGenerator

+ sendUDPDatagram()

SimGenSocket



*

Integrator

Real Spacecraft





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+ notifyObservers()


<<interface>>

ObservedSubject

+ update()

<<interface>>

Observer

+ sendMeasurement()


+ storeDataPacket()

<<interface>>


*

AutonomousFormationControl

OnBoardComputer

GNSSreceiver

<<interface>>


+ sendUDPDatagram()

SimGenSocket



*

Integrator

Real Spacecraft

Produces maneuvers commands based on the nominal orbit calculated

by the OBC.





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+ notifyObservers()


<<interface>>

ObservedSubject

+ update()

<<interface>>

Observer

+ sendMeasurement()


+ storeDataPacket()

<<interface>>


*

Thruster


OnBoardComputer

GNSSreceiver

<<interface>>


+ sendUDPDatagram()

SimGenSocket



*

Integrator

Real Spacecraft





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Component

+ notifyObservers()


<<interface>>

ObservedSubject

+ update()

<<interface>>

Observer

+ sampleMeasurement()


+ storeDataPacket()

<<interface>>


+ logCurrentState()

<<interface>>

DataLogger

*

AccelerometerSimulator

StarTrackerSimulator

GyroscopeSimulator

Thruster


OnBoardComputer

GNSSreceiver

IMU

OnBoardCamera

Produces

maneuvers

commands based

on the nominal

orbit calculated by

the OBC.

High-fidelity Model

+ sampleMeasurement()

<<interface>>


+ sendUDPDatagram()

SimGenSocket

+ storeDataOnUMTFile()


SPIRENT_GNSS_SimulatorWhen SimGen receives

the UDP datagram, it

steers the GNSS signal

simulator physically

connected to the GNSS

Rx.

OMGs have a software reference

only for simulated NMGs. If the

IMU, GNSS Rx, etc... are real HW,

then this relationship doesn't exist

because there shouldn't be software

communication between them.





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: Integrator : SPIRENT_GNSS_Simulator

1: updateState()

: Spacecraft

1.1: getVelAndAccAt()

calculatedState

1.2: notifyObservers()

1.2.1: update()

1.2.1.1: currentState()

currentState 1.2.1.2: generateUDPDatagram()

1.2.1.4: storeDataPacket()

: SimGenSocket

1.2.1.3: sendUDPDatagram()

The high-fidelity spacecraft

state is used by SimGen to

steer the GNSS RF signal

simulator.

After this call completes, the

GNSS Rx may acquire the

GNSS observable.





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Use Precise Orbit Ephemeris (POE) of GRACE-A from NASA repository POE’s have mm and um/s average position and velocity errors, respectively Selected epoch: 8th july 2005 -> no solar storms, no maneuvers Used 30x30 EGM2008, spherical SC, Jacchia ‘71, SRP, albedo, 3rd body gravity Sun-Moon Runge-Kutta-Fehlberg 7/8 integration method Use POE’s as initial conditions

STK/HPOP vs true orbits validation





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XYZ pos & vel errors:

In 90 minutes: 20m & 0.03m/s

In 24 hours: 200m & 0.3m/s

Causes: poor spacecraft model & lack of precise knowledge of environmental parameters in that epoch





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Generation of GNSS observables & validation

Use TG ephemeris and load them into SimGen

Configure SimGen to use ideal GPS Rx (no clock errors)

Load GPS constellation using RINEX file with broadcasted ephemeris (NASA) at propagation epoch

Re-initialize periodically the TG using GRACE-A POE’s to limit synthetic ephemeris errors:





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GNSS validation

Compare generated L1 pseudo-ranges with real ones recorded on board GRACE-A. Results for GPS SVN = 1.

First 90 minutes: 10m errors compatible with standard PR errors

Found 12 hs periodic pattern (GPS orb. period) and 200m error after 24 hrs. -> real and synthetic constellation misalignment

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Framework design for high-fidelity hardware-in- the-loop ... 03/Archivo 0… · I. S. Husain...

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