Test System Architecture for AOCS Testing October 2015 1 Test System Architecture for AOCS Testing S Sudhakar-Group Head, CDEG,ISAC/ISRO Email: [email protected]

Test System Architecture for AOCS Testing

October 2015 1


S Sudhakar-Group Head, CDEG,ISAC/ISRO Email: [email protected]

FSW-2015John Hopkins Applied Physics Lab,Maryland, USA

October 2015


October 2015 2

Agenda

• Introduction• AOCS Test Requirements• Architecture• Design of Various Features• Summary


October 2015 3

DedicatedDiscrete Hardware Units

DOS Based System User I/f + Command Line I/f +8086 Based Unit- AOCE

Digital Unix + Front End Processor (DOS) + Xwindows – AOCEMultiple FEPs

Linux Based Host + Linux Based FEP-Integrated FEP +Qt GUI – AOCE, OBC, NGC, OILS, SILS

Control and Digital Area

Control and Digital

Electronics

Onboard H/w Development

Onboard S/W development

-

Test System Development

-

Hardware Dev Team

In House Hardware

Design, Cards, VLSI

Standard Procured

Units Design

Customised Designs

Software Dev Team

Device Drivers

Applications –Host, GUI

Applications, FEP

Control Dynamics, Simulation

HILS

Integration

Spacecraft Checkout

Mission

Mission Development

Ground Systems Development Areas (AOCS Related)


October 2015 4

AOCS – On Board Computer

Earth Sensor

Gyro

Wheels

Thrusters

S

N

Magnetic Torquers

Star Sensor

PAA

Magnetometer

GPS SPSPayload

PowerTelecommand

OBC

Telemetry

Sun Sensor


October 2015 5

AOCC Functions• Attitude and Orbit Control, Controllers, Filters,

Estimators , Acquisition, Onorbit Modes, Station Keeping Modes

• Sensor Interface - Earth Sensor, Star Sensors, Coarse Analog Sun Sensor, 4pi Sun Sensor, FASS, Solar Panel Sun Sensor, Digital Sun Sensor, Inertial Reference Unit , Accelerometer

• Actuator Interface – Reaction Wheels (RW) , Reaction Control Systems (RCS), Apogee Motor (LAM), Torquer (MTC) , Antenna Pointing Mechanism (APM)

• Onboard Time Reference

• Attitude Reference generation – Model / Profile Based for Normal Pointing, Imaging, Orbit Maneuver

• Orbit Reference generation Model / Profile / GPS Based

• TC, TM

• Mil Std 1553B Bus Control

• Solar Array Drive , Antenna Control

• Safety Logics, FDIR, Autonomy

• Operational Autonomy – Launch Phase Sequencer, LEB sequencer, Payload Sequencer


October 2015 6

Testing Aspects – Different Phases

With Test SystemHardware Tests Software Unit Level TestsFunctional checks Input , output , Logical, computational ChecksSoftware –HW Integrated TestsOpen Loop Tests – Static Open Loop – Dynamic - Tests – Simulated Input Profile (SIP) TestsClosed Loop Dynamic Tests – On Board Computer In loop simulation (OILS) TestsMission Scenario TestsEnvironmental TestsOperational Validation TestsWithout Test SystemHILS- Hardware In Loop Simulation TestsIntegrated Spacecraft Tests


October 2015 7

Ground Test System Design Test System Provides

All Electrical I/f, Power I/f, Loads Multi RT Simulator + Bus Monitor (1553) Electrical Stimuli + Measurements Instruments Supports Open Loop /Closed loop Testing Interface verification Timing Verification OBC/AOCC Simulators for prototype or i/f testing

of other subsystems Software for

Interface Simulation Sensor, Actuator Models Orbit Model, Sun Model Dynamics Simulation Automatic Testing GUI, RT Plot, Display, Data Logging and Retrieval Mil 1553 Bus Monitor

Front End Processor

System Under Test

Host

Located Near SUT - AOCC

Linux BasedRT – With PCI based Add on

cards + Hardware

Linux BasedHost

• Distributed Architecture• Host System – Data Processing,

User Interface, Simulation

• FEP ( Front End Processor) System – Data Acquisition, System Interface

• Dedicated Ethernet Interface


October 2015 8

Ground Test System Elements


October 2015 9

Typical Test System Architecture


October 2015 10

Software Architecture

TCP/IP

FEP software: 1553 Receive

Data, data Acq, 1553 Monitor

data

TM-External Data Acq Systems

(DAS)

HK Data

High Rate Data Acq data

MIL-1553 Data

HOST software: Data processing, RT plot, log and

User displayAuto TestHK TM Client socket

Dwell/PB-TM

Normal-TM

FEP software: command, sensor Actuator, Analog,

digital simulations, 1553,

HOST software: s/c model,

sensor/actuator Model

SIPOILSSILS

Tele-Commands

Sensor

Actuator, OBC Sync signals

1553 Pkts Sen/Act

Data socket

Data Processing ( Non RT)

Data Processing ( RT ) AOCS

HOST software:Open Loop Test

Auto TestTC


October 2015 11

Realtime Management

• Processes segregated to RT, Non RT• Priorities maintained accordingly• Scheduling - FIFO• Inter Process communication• Shared Memories• Message Queues• Semaphores

• Kernel Preemption enabled• Memory Locks provided• Double buffered interfaces• RT Diagnostics• Deadline Miss Counters• Parallel Integration in TS to compare

with Flight

Realtime Processes

• FEP Software• FEP Communication Software at Host• Sensor, Actuator, Mil 1553 Interface

Software• Spacecraft Model Software• OILS, SIP Interface Software

Data Processing Software + GUI• Telemetry, Data Stream Acquisition

Software.• RT Plotting• GUI• Page Display• Command, Open Loop test software

Offline – Non RT• Logging + offline software

Real Time / Non Real Time Management


October 2015 12

Different Processes Organisation – For open loop

Data Process

ing

DAS Data

Data Log

User

Open Loop

Test I/F GUI

TC Process

ing

Sensor Actuato

r I/f

Spacecraft

Model

FEPSystem Under

Test

RT Plotting

, Utiities

Open Loop Test

Sensor Stimuli

Telecommand

Test System Settings

Mil 1553B Stimuli, Bus

HandlingInstruments

Dynamics, Initial

Conditions SettingsOpen Loop Static Tests:

• All Logical Tests for Sensor Inputs and Actuator Outputs

• Performance of AOCS – Gains verification• Open Loop AOCS mode Test Vector reading,

processing, Verification• Sync with Onboard wherever required.


October 2015 13

SIP Software

Buf1 Buf 2

Data Files Test System Software

Simulated Input Profile – Open Loop Dynamic Tests

• Validates the AOCS / NGC Loops• Open Loop Dynamic Testing• Actuator to Sensor Closed loop is by Simulated Profile ( i.e Loop through Test System is opened)• Every Sensor Step input is simulated• Requires high Real Time Performance + Synchronised to Onboard

• RT Techniques Employed• Double Buffering• File readout + Update Test system I/f• Onboard Sync handling with real time sampling• Process Priority Management

• Sync With onboard• Advanced Information from Onboard• Advanced Data Update to onboard


October 2015 14

Fig 2.0 OILS (On Board In Loop Simulation)

Actuator data Reading

•Thruster Firing On time Measurement•Wheel TachoData Reading

Spacecraft Dynamics

Model

Body rate and error

calculation

AOCE (Main & Redt)

Thruster Torque

calculation

Thruster torque table

Wheel Torque

calculation

Wheel Matrix

Star Sensor Q’s update

DTG rate update

SS mounting matrix

Gyro matrix

`Wheel matrix

CASS matrix &Sun Model

`

Sensor Simulation•Gyro rate •Star Sensor Q’s•CASS error angle•Wheel speed

Wheel speed update

CASS error update

SADA/ SPDM angle

calculation

Closed loop Simulation

Potentiometer update

Actuator data Reading

•Thruster Firing On time Measurement•Wheel Torque Data Reading•Magnetic Torquer

Spacecraft Dynamics

Model

Body rate and error

calculation

AOCE (Main & Redt)

Thruster Torque

calculation

Thruster torque table

Wheel Torque

calculation

Wheel Matrix

Star Sensor Q’s update

DTG rate update

SS mounting matrix

Gyro matrix

`Wheel matrix

CASS matrix &Sun Model

`

Sensor Simulation•Gyro rate •Star Sensor Q’s•CASS •Wheel speed• SPSS

Wheel speed update

CASS /SPSS rror update

Typical Onboard Computer In Loop Simulation

OILS• All Dynamics Logics verified.• Interface simulations remain same• Inputs for Interface simulation arrive from OILS• For Closed Loop NGC Six D Dynamics are

simulated + Accelerometer + GPS data simulation


October 2015 15

Data Scheduling & Synchronisation

DAS s/w FEP

AOCS ReadsGyro

DAS s/w FEP

Sensor I/f S/w Host

Actuator I/f

S/w Host

Sensor Model

Actuator Model

Open Loop

SIP

OILS

SpacecraftModel

InterfaceProcess

FEP Data Acq

Sync Cycles8ms

Sensor Data Update

Actuator Data Read

Y,R,P

Torque

Sensor I/F

ActuatorI/F

Data I/F

Data I/F

AOCSData I/F

Synchronisation Processes Involved:• Async / Sync Mode• Synchronisation with Onboard• Sync with respect to Signal – • Parallel Accumulation / Integration• Simulation runs at higher Resolution – say 2ms• Integration cycle is submultiple of onboard clock – To ensure proper Integration & transfer of data wherever required.


October 2015 16

Interface Simulation Software -Sensors

Sensors / Any Input Stimuli • e.g. Star Sensor, Battery Current, Solar Array Drive Pos• OO Based approach • Component - Database Driven• Component Data Base – Describes Types

Earth Sensor / Star sensor• Project Database – Objects from above components –

Declared – Each instance of sensor + other Info• Shared Memory for Interface Level inputs• User Input / OILS / SILS Input

• All Sensor Interface Inputs• Bias, Correction, Scale factor Provisions. (like Drift,

Misalignment etc)• Update Rates ( If variable)• Sensor Modes (If variable)• Latency ( If required)

• Inputs for FDIR Simulation• FDIR at Interface Level simulation

• Output for• FEP communication Interface

ESSen1

ES

Stimuli I/f

Processing

Sensor Model

Commn I/f

FEPOpen loop/OILS/SIP

Components

Sen4SS

Project DatabasesInstances


October 2015 17

Interface Simulation Software -Actuators

Actuator / Any Output• e.g. Reaction Wheel, Torquer, Thruster ,

Solar Array Drive, Antenna Control• OO Based approach • Component based - Database Driven

• Component Data Base – Describes Types Wheel, Thruster

• Project Database – Objects from above components – Each instance of Actuator + Other Info

• Shared Memory for Interface Level inputs• Output to OILS• Inputs for FDIR Simulation

• Failure simulation for Actuators• Output for• Actuator Model

RWAct1=RW

Actuator I/f

Processing

Actuator Model

Commn I/f

FEP

Open loop/OILS/SIP

To Stimuli

Act5=MT

C

ComponentsProject DatabaseInstances


October 2015 18

Spacecraft Model ProcessModels for Open Loop Testing:• Orbit Model• Orbit Profiles• Selection for Orbits • Sun Model

• Attitude Reference Model• Attitude Reference Profile• Functional – sun Pointing, Earth Pointing etc

• Sensor Model• Mounting, Bias, Misalignment, Scalefactors• Sensor Modes• Noise Model

• Actuator Models• Mounting, Dynamics Model

• Specific Models• Solar Array Drive to Array Angle generation

• For Closed Loop testing• Sun and Earth Reference for Validation• Spacecraft Dynamics • Six D Dynamics for Navigation Computer.

Attitude Model

Orbit Model

Sun Model

SpacecraftDynamics

Sensor Model

Actuator Model

From I/F

To I/f

Data / Coeffts

Time Sync


October 2015 19

Time Sync Interfaces

Time Synchronisation Interfaces• Test System Maintains separate Time• Counter at FEP• Transferred to host at Actuator cycle

• Time Synchronisation• Time sync done at Host• Provision to offset, Sync, Start with a

particular Date to simulate Overflow etc.• Normally one time sync and Periodic

Verification

• On Board Time Sync• Through Discrete I/O ( at OBT Reset)• Through TM Stream – As carried out in

Mission• From Payload Time sync Transfer

For Events• Advanced Event Info like Navigation Start• Maneuver Start for Profiling Error

OBT Reset Event

Payload Time Event(Periodic) & Any time

Downlink Stream(Periodic) & Any time

Test System OBT process

Hardware TimerFrom FEP

Provision for Bias, Offset, drift to match onboard

Time Ref for Models


October 2015 20

Typical Star Sensor Simulation

Profile RefProfile Ref

Data Reading

Transform to S/c Frame

Latency Correction

Update Attitude

Sun Ref

Earth Pointing Ref

FEP I/f Simulation

Host I/f Simulation

Body to Sensor

( Sensor Model)

Sensor I/f

Sun Ref

Earth Pointing Ref Attitude ErrorAttitude Error

Time Sync

32ms REFT n REFT n+1 REFT n+2CCD Integration

Delta t

Any ErrorIn Time syncOr onboard Time errorLatency shows up


October 2015 21

Test System

Data Processing

Onboard Telemetry

Payload Aux

Actuator DataMil 1553B

Read out DataInstrument Measurements

Dynamics Data

Test System HK TM, TC Mon

Data Processing Software• Real Time - For OILS, Open Loop tests• Thruster On time data• Motor Pulse data• Torque Data from Wheel, Torquer

• Non Real Time• Telemetry Streams – Typical 6, • Test System House Keeping – 1 Stream• Actuator Data – Sampled, Formatted –

Wheels, Antenna Drive for open loop Validation

• Mil 1553 Data Received by RT• Payload Aux Data• Dynamics Data

• Processing Data Base Driven (Parameter IDs)• Map Info provides mapping from Stream data

format to TS channels

Data Processing Software


October 2015 22

Data Processing Databases

Typical

• Upto 50 Streams ( 25 Typical)• Data Rates 4kbps – 32kbps• Multiple Frames• Typical 10000 TS channels• Typical 100 Post Processing channels • 6000 PIDs• Upto 40 Processing Types• Bit Info• Byte/ Word• Hex, Decimal• 2’scomp, Bin • IEEE, 1750 Formats• Time formats

BPTCUpSVSts1 No:1901 type:9 wno:3582,3433 And:80 shift:7 Data:2 data:stringAORSteps No:1902 type:11 wno:3564,3421 data:ushortPosX_OrbtCtrl No:1903 type:16 wno:3566,3423 A:0.305185 B:0.000000 UL:10000.000000 LL:-10000.000000 Err:0.100000 Unit:kms data:floatPosY_OrbtCtrl No:1904 type:16 wno:3568,3425 A:0.305185 B:0.000000 UL:10000.000000 LL:-10000.000000 Err:0.100000 Unit:kms data:floatPosZ_OrbtCtrl No:1905 type:16 wno:3570,3427 A:0.305185 B:0.000000 UL:10000.000000 LL:-10000.000000 Err:0.100000 Unit:kms data:float

STREAM 0FRSYNCNO 3FRSYNCCODE AC_CA_1F_FRID 4NOOFFRAMES 64WORDSPERFRAME 128PROCESSRATE 128DWELL 1FRSYNCCHK 1WRDSFROMIF 66RAWDISP 1MAPCHANNEL 0DEFCHAIN 0DEFLOG 1DEFPROC 1MAPSTART 0MAPSIZE 4900MAPCODE PPOSTPROCSTART 9500POSTPROCSIZE 200ALWAYSPROCSTART 9698ALWAYSPROCSIZE 196

Typical Stream Infotypedef struct{ Value PIDValue; char cParameterName[PARAMETER_SIZE]; char cDisplayValue[DISPLAY_SIZE + 10]; char cOldValue[DISPLAY_SIZE + 10]; int iDisplayInfo; int iPlotCounter; /* counter to indicate plotting for the PID is requested by the clients */ int iAnamoly; int iFilter; float resolution; int DataType; /*verification */ int iVerify_reqd; // 1 or 0 int iVtype; // 1: int, 2: float, 3: compare Value Verify_value; float deviation; char Verify_attr[DISPLAY_SIZE + 10]; // 0: OK, 1: Not OK, 3: No Verification /*log on change */}

Typical PID Structure


October 2015 23

Typical Data Processing Software

Initialisation• Read Data Bases PID Data, Map Data,

Stream Info• Create Linked Lists, Cross Ref Lists

• On Receiving Stream Data• Log the Stream Data• For Every Sub Block of Stream Data

• Map the Stream Data to TS Channels• For Each TS Channel Updated

• Process all Affected PIDs • For all the Post Processing TS

Channels Updated• Process all Affected PIDs

• Update the PID Data for all the Logging Plotting Utilities through Queue

( RT Plotting, Anomaly, Automatic Testing inputs)

Stream 1

Map 1

PID Linked ListTS Channels

Stream 2Stream 3

Stream n

Map 2Map 3

Map n

Post Processing Updates


October 2015 24

Front End Processor Software

Device Drivers• Mil 1553B Multi RT Simulator• TC Encoder• ISR 1ms• Data Acquisition Driver Analog, Digital• Functions for Sync Mode with SUT /

Non Sync Mode

• Applications• Host – FEP Communication 1• Mil 1553 B Handling and Host

Communication 2• For Real Time Data• For Stream Data ( Non RT)

• Mil 1553 Bus Monitor• Instruments Readout

• Power Supply, Current Meters

1553 FEP

1553 Host

Real Time

Data Proces

sing Softwr

awe

Non 1553

I/f

Non 1553 Host

1553 Device Driver

1553 Bus

Monitor

Hardware

Device Driver


October 2015 25

FEP Software Features

Multithreaded architecture with pthread level synchroniszation between threads.

Data Acquisition + Simulation with a granularity of 1ms with Hardware interrupt.

• Time Synchronization option with GPS time source.

Real time I/O performance is required.

Intel/AMD processors and real time variants of Linux - used in test beds.

FEP Software Features


October 2015 26

Testing FDIR Logics

FDIR Logics

• Requirements for providing all Interfaces for FDIR• Nominal and Non Nominal Simulations• Negative checks verification• Verification of Time checks – require synchronised Real time

simulation. ( Carried out in the lines of SIP mode)• Event Handling - Time line to be simulated in TS

( To simulate exact action)• Interface Level failures simulation

• Checksum errors• Latency Errors Simulation• Complex with Multiple Buffers

Error Simulation-Ve checks

Error Simulation+Ve checks

On Board Cycle and TS cycle synchronisedFor simulations


October 2015 27

Software In Loop Simulation

Host Software ElementsWithout Any change

Actuator I/F

Dynamics Model

Sensor I/F

Simulation

AOCCH/w

Sensor I/F S/w

Sensor Model

Actuator I/F s/w

Actuator Model

AOCCSoftware

AOCCH/w

Actual AOCC software Emulated in Host

FEP H/w EmulationIn Host

Open Loop /

SIPTest I/F

AOCC Hardware Emulation in Host

Software In Loop Simulation

• Full Software Platform to Test all AOCC Software Functions• Simulation of All Hardware / Interface Elements by Software Aimed mainly at :

Logical ChecksComputational checksData FormatsMil 1553 I/FHK Data Checks

• Platform for Mission Operations Simulation


October 2015 28

Verification for critical Mission Phases

Hardware Verification if RequiredSoftware Verification in All Phases Integrated Spacecraft Test – Simulations if any.Launch Phase Sequence of Events VerificationPayload Operations Profile VerificationSafety Logics / FDIR logics VerificationCritical operations like MOM EBN, TMI, TCM, MOI Phase

Rehearsal of OperationsProfile Validation, Accuracy EstablishmentProgrammable Autonomy like

Event Based Command logic verificationRemote / Patch Update Verifications


October 2015 29

Other Features

Test System Features

• Page Display

• Real Time Plotting

• Inter Message Queues between RT Plot and Data Processing Software

• Data Logging

• Real Time Commanding, Delay Simulation

• Off Line Data Processing

• Same as RT Data Processing – Data received from File

• Automatic Testing

• Testing of Open Loop Test Vectors

• Automatic Verification OK/Not OK

• Auto Test Language with Script Files with

various Features.

Other Test Systems

• BC Simulators ( OBC Simulators)

• Test System for Motor Drive Electronics ( Antenna Control, Payload

Platform Control)


October 2015 30

Major causes of Error in Testing / Simulation

Test Level

• Simulation Assumptions / Actual Information not available

• Time Synchronisation Errors

• Scenario / Sequence Coverage

• Accuracy, Precision, Sampling Simulation Errors

• Test coverage is not complete/insufficient test cases

• Actuator I/f clearance with Diagnostic TM rather than actual actuator output.

• Insufficient Test – especially less critical ones like TM

• Independent Tests – Interrelated effects missing

• Test Limitations

• Simulation Errors

Solutions Proper ICDs Mission Scenario Tests Operational Validation Identification of simulation

limitations and addressing alternate methods of validation

Analysis, Review and Process Implementation

Test case generation from requirements /Test Review Boards/Test procedure review/ Automation of testing / Test Results Review

Observations tracking and guidelines/check list generations


October 2015 31

Summary & Future Enhancements.

The Distributed Test System Architecture has been used extensively for AOCS, Integrated OBC, NGC applicationsWith little modifications, same frame work is being used for HILS.Continuous improvements in terms of Automation, Simulations, Data Presentations, Validations are being done.Increased real time performance, Inclusion of Flexibility dynamics for Closed loop simulation & higher models - the requirements for AOCS are being continuously improved / added.Software In Loop simulation – being developed for Testing, Operational requirements. Hardware Modelling is also being attempted.Standard Auto Test Languages, Databases are to be explored.Miniaturisation in Hardware is being attempted.


October 2015 32

Acknowledgements are Due to

• Dr. A S Kiran Kumar, Chairman ISRO• Dr. M Annadurai, Director ISAC• Mr. Subramanya Udupa, DD, CDA, ISAC• Colleagues and Team members of

Control and Digital Electronics Group,

Sincere thanks to• Dr. Allen D Unell, Chairman FSW-2015• Mr. Subodh Harmalkar, FSW-2015, APL

[email protected]

Documents

Test System Architecture for AOCS Testing October 2015 1 Test System Architecture for AOCS Testing S Sudhakar-Group Head, CDEG,ISAC/ISRO Email: [email protected]