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ć»Definition of Systems Engineering
ćExplanation and Other Informationć
ć»What is System Engineering (SE) ?
The Systems Engineering (SE) is an engineering methodology and a series of related activities for successful realization of the objectives, i.e. mission requirements.ć
ć»System engineering is defined as an interdisciplinary approach governing the total technical effort to transform requirements into a system solution1).
1) ECSS-E-ST-10C, Space Engineering, System engineering general requirements
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ć»What is systemļ¼
ćExplanation and Other Informationć
ć»System is defined as a collection of functional elements achieving specified objectives with higher performance than a simple sum of the elements.
ć»Total system of spacecraft consists of space segment, launch system and ground segment as shown in Figure 1-1.ćTypical composition of space segment is shown in Figure 1-2.
ć»Space Infra-structureļ¼Space Infra-structure means the industry which relates to
space activities such as makers of space equipment, processing companyes of observed space data, users of space data and so on.
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Total System of Spacecraft
ćExplanation and Other Informationć
ā Launch System: Launch Vehicle, Launch Facility
ā”Space Segment: Observation Satellite/ Payload, Bus, (Data Relay Satellite)
ā¢Ground Segment: Data Acquisition Station, Tracking & Control Station
ć
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Typical Spacecraft Configuration
ćExplanation and Other Informationć
ć»Spacecraft: Bus, Payload(Mission)
ć»Bus consists of the followings;
ćStructural S/Sļ¼maintains the position of equipments.
ćPower S/Sļ¼Creates the electric power from the solar and stocks it.
ćThermal S/Sļ¼Thermal control of spacecraft.
ćADCSļ¼Attitude and orbit control of spacecraft.
ćT & C S/Sļ¼Telemetry and command subsystem.
ćPropulsion S/Sļ¼Puts a satellite into orbit
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Boundaries of the system engineering discipline
ćExplanation and Other Informationć
ć»Managementļ¼ Cost, Planning, Configuration control, Procurement, Information, Documentation
ć»Product Assuranceļ¼Product assurance, Dependability, Verification, Procurement, Criticality analysis, PM&P, Safety, EEE component (S&MAļ¼safety & mission assurance in JAXAļ¼
ć»Productionļ¼Development M.A.I.T(manufacturing, assembly, integration and test)
ć»Operations and Logisticsļ¼Operations Engineering, Operations Verification, Logistic Analysis
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SE process and V-chart (1/2)
ćExplanation and Other Informationć
ļ¼SE processļ¼ć:
Customerās Needs ļ Mission statement(MS)ļ Technical Requirements Specification (TS)
ļ ā Mission Description Documentļ¼MDD)
ļ ā”Optimum System Selectionļ¼Trade-offļ¼
ļ ā¢Decomposition of System to Sub-systems
ćļ¼System ļ Sub-system ļ Componentļ¼
ļ ā£System Specification ļ Sub-system Specification ļ ICD
ļ ā¤Verification of Sub-system Characteristics
ļ ā„Integration of Sub-system to upper Systemć ćć
ļ ā¦Verification System Characteristics ļ Launch ļ Operation
MS: Mission statement,ćććTSļ¼Technical requirements specification
MDD: Mission description document
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SE process and V-chart (2/2)
ćExplanation and Other Informationć
ććććććļ¼Development ļ¼ć
ā Strong SE Organization
ā”Effective Objectives and Detailed Mission Analysis
ļļ Cooperative Work with Customers & Suppliers
ā¢Rigorous Decomposition and Allocation of Function to lower Sub-systems
ā£Clear Requirements and Clear Interface between Sub-systems
ā„Effective and Efficient Development and Product assuanceļ Phased Project Planning (PPP)
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Transition of System Engineering Effort
ćExplanation and Other Informationć
ć»The role of SE effort is most important in initial stage of development
System feasibility should be ensured to define the mission requirements. It requires a rough system design ļ¼i.e. Concept Study and Concept Design ļ¼ including operations concept and verification procedures. In addition, detail analyses on subsystems and components are also necessary to examine the feasibility of system. If these activities are well performed as front-loading in the early phase of development, the major activities in the later phases can be put on management of manufacturing and procurement, integration and testing as planned in the project management. This figure illustrates the roles of the system engineering and the project management.
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V chart in System Development
ćExplanation and Other Informationć
ć»V-chart is shown in this figure.
ć»The first step is to define the mission requirementsćclearly. System functions are to be defined based on this requirements and the associated constraints,
then, they are decomposed into elements from the top level to the bottom, and carefully examine relationships among the decomposed elements. It is followed by integrating the decomposed elements into appropriate subsystems, with checking if they fulfill the assigned functions. Finally, all the subsystems are integrated into a system and verification in operational conditions is required. The āVā curve in this figure shows this series of activities. The idea is to identify the whole processes into decomposition and Integration by folding it in the middle to form a āVā shape. This allows us to compare the outputs (or products) of both sides on the same level and to validate them with requirements from upper-level.
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PPP (Phased Project Planning)
ćExplanation and Other Informationć
PPPļ¼PPP is the development procedure created by NASA in APOLLO project.
ć»In PPP, the development stage is divided to plural phases where the necessary activities are defined. The result performed in each phase is estimated in Review meeting, and the migration to next phase is approved.
ć»NASA, ESA and JAXA use this PPP procedure.
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JAXAās Definition of Activity in related Phase
ćExplanation and Other Informationć
ć»There are no difference in the basic concept of phase activity in JAXA and NASA.
1)Concept studies: Define mission requirements : Phase 0
2)Concept design & Approval of Plan: Define system requirements, Architecture design: Phase A
3)Preliminary design: System specification, Define subsystem requirements and design subsystems: Phase B
4) Critical design: Subsystem Specification, implementation drawings and verification plan: Phase C
5) Manufacturing & test: Manufacturing, system assembly and test: Phase D
6) Launch site Preparations: Launch the spacecraft: Phase E
7)Operation: Operations and sustainment/Closeout or disposal: Phase F
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Concept studies (Phase O)
ćExplanation and Other Informationć
Phase 0: Concept studies: Define mission requirements.
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Concept studies (Phase O)
ćExplanation and Other Informationć
(1) Clarification of Mission Requirements :
Requirement Analysis shall be performed and Mission Definition Document(MDD) shall be made which clarify the mission requirements to be able to image the system design. ć
Requirement items: function, performance, Interface, environment, resources, physical items (size, weight,--), design standard, quality assurance and so on.
Quality of requirements: completeness, consistency, traceability, testability, unity.
Requirement analysis process: Mission statement by customer->clarify the environment -> clarify the product.
(2) Clarify the precondition:
Design philosophy , budget, reliability, launch vehicle, etc.
(3) Requirements to system and Mission Definition Review(MDD)System :
System architecture and system decomposition shall be performed based on the mission requirement analysis and the precondition and reality of the system shall be confirmed.
Total system specification, Operation concept and Development specification shall be documented, and shall be reviewed at MDR together with the Mission definition document.
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Concept Design (Phase A)
Concept design &ćApproval of Plan
ćExplanation and Other Informationć
ć»Phase A: Define system requirements, Architecture design
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Concept Design (Phase A)
ćExplanation and Other Informationć
Concept Design: Feasibility design shall be done to satisfy the system requirements derived from mission analysis and system constraints.
ć»Evaluate some alternative technologies and configurations to satisfy functional and design requirements in early trade-off study.
ć»Major evaluation criteria for trade-off includes:
ćć1)ćCost : generally a dominant factor
ćć2) Mission performance : image quality
ćć3)ćPhysical characteristics, mass, size and power
ćć4)ćTRL: Availability of suitable hardware technology and any predevelopment
ć (Heritage, maturity, existing hardware or predevelopment hardwareļ¼
ćć5)ćDevelopment schedule
ćć6)ćReliability and dependability
ćć7)ćCompatibility with launcher, ground system and other system
ć»Analysis and selection of system candidates ļ System design document
ć»1st definition of subsystem performance through the subsystem trade-off.
ć»Document the system specification ļ Review at SDRļ¼System Definition Review)
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Trade-off study (Phase A)
ćExplanation and Other Informationć
Trade -off study ; using preliminary analysis tools (calculator or PC)
Payload selection : Radar / Optical sensor, FOV(Swath), Tilting system,..
Orbit design: Sun synchronous orbit (SSO) / Non-synchronous orbit, Altitude, Local Time (LT), Position sensor,ā¦ .
Power: Array sizing, panel shape, buttery sizing, solar cell,ā¦
Mission data transmission: Data rate, storage capability,..
Thermal control: Active or passive control, tolerant temperature..
Configuration and mass distribution of spacecraft: Dry mass and wet mass, stowed and deployed configuration, position of sensors,ā¦
Field of view
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System Analysis (Phase A)
ćExplanation and Other Informationć
ć» Rough analysis using simple program or calculator
1)Power ļ¼Profileļ¼ Analysis (Including Operation mode)
2)Pointing Analysis (Agility: slew rate, error budget of sensor, alignment, etc)
3) Thermal Analysis, 4) Structural Analysis, 5)Mass properties,
6) FOV interference (Antenna, optical sensors),
7) Data Quantity (Memory size requirements)
8) Communication link analysis (Data rate requirements),
9) Radiation Environment, 10) Reliability and etc
ć» system budget , margin policy ļ system analysis
1)Mass and mass properties, 2) Power consumption budget,
3) ĪV and associated propellant quantity, 4) Pointing and stabilization,
5) Alignment (Error budget),
6)Telemetry (including sampling rate) and command budgets
7)Data rate and storage capability, 8)Communication link budget,
9)Reliability budget
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Preliminary design: Phase B
ćExplanation and Other Informationć
ć»Phase B: System specification, Define subsystem requirements and design subsystems
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System Design((Preliminary/Critical Design)
ćExplanation and Other Informationć
ć»System Design shall be performed from System Specification (same in the critical design).
ć»System trade-off analysis shall be performed in the consideration of a variety of technical fields.
ć»System designer shall perform the followings;
ć i) Environmental conditions to equipments, such as loads in lift-up which are vibration, shock and etc. and environmental loads in orbit which include radiation, electrical charge and etc.
ććii) Design standardļ¼Mechanical design, electrical design, thermal design, EMC design and etc
ććiii) Subsystem specificationļ¼AOCS, EPS, T&C, PROP and etc.
ć»System designer shall prepare the operation plan, perform the system analysis and determine the system parameters.
ć»These output are reviewed at Preliminary Design Review (PDR).
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Preliminary Design (Phase B)/Trade-off
ćExplanation and Other Informationć
The system engineer shall conduct or consolidate trade-off analyses to:
ć»assist in selecting system concepts, designs and solutions (including people, parts and materials availability);
support material selection and process decisions;
support make-or-buy and supplier selection;
examine alternative technologies to satisfy functional and design requirements;
evaluate environmental and cost impacts of materials and processes;
evaluate alternative physical architectures to select preferred products and processes;
establish the system and its configuration items;
analyze planning critical paths and propose alternatives;
select standard components, techniques, services and facilities that reduce system life-cycle cost;
establish model and product verification philosophy for achieving qualification and acceptance objectives while considering testability;
assess design capacity to evolve.
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Environmental Requirements
ćExplanation and Other Informationć
Spacecraft shall be designed considering the following conditions:
ć»Ground activities (transportation, handling condition)
ć»Launch & ascent condition (depend on launch vehicle and spacecraft)
Structural input and loads
Shock (caused by ordnance devices for separation)
ć»Operating orbit condition (depend on orbit and spacecraft configuration)
Shock (caused by ordnance devices for deployment)
Thermal input, range
Radiation, Ultra-violet rays, Atomic oxygen and etc.
EMC
Spacecraft charge (static charge)
Contamination by out-gassing and/or propulsion gas (against optical sensors)
Space debris
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Verification Test Plan
ćExplanation and Other Informationć
What tests shall be done and what models shall be built ?
ā Mandatory + Optional (Quality, Risk and Cost compromised)
ć»Parts/Material:
Thermal shock/ Shock/ High Frequency Vib./ Radiation test (Screening)/ PIND/ X-ray/ Life-cycle test , etc.
ć»Component Level:
EM, PFM ; Sinusoidal Vib./ Random Vib./ Shock/ Thermal Vacuum test (temperature test)/ EMC test
ć»System Level:
EM: Functional Test/ EMC
SLM: Static Load test
STM: Dynamic Load test
PFM:ćFunctional Test/ Mass Property/ Alignment/ Dynamic Load test (Acoustic, Vib. etc.)/ Thermal Vacuum
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Mission operational design
ćExplanation and Other Informationć
System engineer shall perform following activities,
Mission Operation Plan ćāćpower requirements and thermal design
Maximum / Normal / Minimum
Mission Operation(including data transmission) in eclipse (required or not)
Power Profile Analysis
ććććććāćsizing of power system, operational constraints
Solar power required in EOL(End Of Life)
Power consumption profile in day time and eclipse
Batteries charge and discharge
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Preliminary Design Review (Phase B)
ćExplanation and Other Informationć
At the end of phase B, Preliminary Design Review (PDR ) shall be performed.
The objective of PDR is ; To demonstrates that the preliminary design meets all system requirements with acceptable risk and within the cost and schedule constraints.
As a result of PDR, the design to baseline is approved and is authorized to proceed to the detailed design (phase C).
Documents reviewed at PRD
system specification, subsystem development specification
subsystem interface document
EMC specification, environment specification
Interface control drawing (ICD)
Verification plan
system drawings (Development model, EM, STM, etc.)
system parameters (mass budget, power budget, etc.)
Sequence of Event (SOE), spacecraft operations procedure (SOP)
EEE parts list, material and processing list, etc.
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Critical Design (Phase C
ćExplanation and Other Informationć
ć»Phase C: Subsystem Specification, implementation drawings and verification plan
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Critical Design (Phase C)
ćExplanation and Other Informationć
Design
The methodology of system analysis is almost same as before, but the parameter and data base used for analysis is more precise.
The design of system, subsystems, components are refined in detail.
Development test (design verification test)
The design verification which involves test of software and Engineering Model (include Structural Model, Thermal Model, etc) are performed as required.
The verification by test is mandatory for new design.
End-to-End test and polarity verification test are strongly recommended to extract potential interface inconsistency.
The tests shall be performed under the severer conditions* than the estimated flight conditions to verify the validity of design (including margins).
*Qualification Test Level
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Critical Design Review (Phase C)
ćExplanation and Other Informationć
The objective of Critical Design Review (CDR)
ć» To verify that the detailed design meets system requirements.
ć» To demonstrates that the maturity of the design is appropriate to support
proceeding with full scale fabrication, assembly, integration, and test, and that the technical effort is on track to complete the flight and ground system development and mission operations to meet mission performance requirements.
ćAs a result of CDR, the build-to baseline, production and verification plans are approved, and project are authorized to proceed to next fabrication and test phase (phase D).
Following documents shall be prepared for CDR
ć»Final System/Subsystem /Components specifications,
ć»Final Interface control documents (ICD), ć»Drawings (for PFM or FM)
ć»Final EEE Parts, Material, & Processes List
ć»Test Plan, Test specification and evaluation plan (for PFT or AT)
ć»Preliminary Spacecraft Operational documents (SOE, SOP, etc)
SOE: sequence of events , SOP: spacecraft operations procedure
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Manufacturing and testļ¼phase Dļ¼
ćExplanation and Other Informationć
ć»Phase D: System assembly and test
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Proto-Flight Test for Systemć(Typical)
ćExplanation and Other Informationć
ć»Flow of Environmental Test
Initial Performance Test (IPT)
ļ Vibration Test ļ Functional Test, Alignment/Leak
ļ Acoustic Test ļ Functional Test, Alignment/Leak
ļ Shock Test ļ Functional Test, Alignment/Leak
ļ Thermal Vacuum Test ļ Final Performance Test (FPT)
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Pre-Shipment Review (PSR)
ćExplanation and Other Informationć
After the completion of PFT, Pre-Shipment Review(PSR)
shall be performed. System engineer shall support PSR activities.
Confirmation at PSR includes;
Compliance with the test verification matrix
Acceptability of all non-conformances, failures, waivers
Any data to the trend (no remarkable change or drift of data)
Post shipment plans
Launch preparation plan
Operation plan
