General

JERG-2-152A

DISTURBANCE CONTROL STANDARD

May 10 , 2012 Revision A

Japan Aerospace Exploration Agency

JERG-2-152A

This is an English translation of JERG-2-152A. Whenever there is anything ambiguous inthis document, the original document (the Japanese version) shall be used to clarify theintent of the requirement.

Disclaimer
The information contained herein is for general informational purposes only. JAXA makes
no warranty, express or implied, including as to the accuracy, usefulness or timeliness of any
information herein.

JAXA will not be liable for any losses relating to the use of theinformation.

Published by
Japan Aerospace Exploration Agency
Safety and Mission Assurance Department
2-1-1 Sengen Tsukuba-shi,Ibaraki 305-8505, Japani

JERG-2-152A

Contents
1.

2.

3.

4.

General Provisions ...........................................................................................................1
1.1

Purpose .................................................................................................................... 1

1.2

Scope ....................................................................................................................... 1

1.3

Related documents .................................................................................................. 1

Philosophy of disturbance control ....................................................................................2
2.1

Spacecraft and disturbance ..................................................................................... 2

2.2

Influence and classification of disturbances ............................................................ 3

2.3

Necessity for disturbance control ............................................................................ 6

2.4

Details of disturbance control .................................................................................. 7

Process of disturbance control.........................................................................................8
3.1

Disturbance requirement analysis in accordance with mission requirements ........ 8

3.2

Disturbance control requirement setting .................................................................. 8

Disturbance control in each phase of spacecraft development.......................................9
4.1

Concept and preliminary design (conceptual design) phase ................................ 10

4.2

Basic design review (EM phase) ........................................................................... 13

4.3

Detail design and manufacturing phase (PFM phase) .......................................... 14

4.4

Orbital operation phase ......................................................................................... 16ii

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1.
1.1

General Provisions
PurposeThis standard specifies the disturbance control of artificial spacecrafts and interplanetary
probes developed by JAXA.
1.2

Scope

When being applied to specific projects, the standard shall be tailored according to theconditions of each project.
1.3

Related documents(1) JERG-2-500 Control System Design Standard(2) JERG-2-510 Attitude Control System Design Standard(3) JERG-2-151 Mission and Orbit Design Standard
References(1) Artificial Spacecraft Dynamics and Attitude Control Handbook, published by Baifukan in
2007

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2.

Philosophy of disturbance control

2.1

Spacecraft and disturbance

The forces that act upon the spacecraft and spacecraft's internal elements can be classified
as shown in Figure 1. Of which change the spacecraft attitude, mission instrument functions
and performance (including pointing accuracy) and affect the micro- vibration environment
within the spacecraft, internal forces other than intended controlling force and control torqueshall be defined as internal disturbance (disturbance for short). Internal forces are thegeneral term for interacting forces and torques between elements in the spacecraft.
Intended controlling forces
and control torques
Forces and torques
acting upon thespacecraft and internal
elements
External disturbance(unintended forces andtorques)

DisturbancesourceDisturbance propagation(Movement and vibration causedby disturbance)

External force: External disturbancein a more limited senseInternal Forces

Disturbance sensitivity(Impact on the functions andperformance of spacecraft andmission instrument)

Figure 1 Definition of disturbance
The movement of a mass generating disturbance or the instrument including the moving
mass shall be defined as a disturbance source. The generated disturbance causes
movement (including vibration) of the spacecraft or mission instrument (referred to as
disturbance propagation) and affects the functions and performance. When the functions
and performance of a spacecraft and instrument are affected by disturbance-induced
movement (vibration), the spacecraft and instrument are disturbance-sensitive.
This design standard specifies the process for controlling the disturbance sources,
disturbance propagation and disturbance-sensitive instrument to achieve the functions andperformance of the required spacecraft and mission instrument when there is a disturbancesource inside the spacecraft and the spacecraft has disturbance-sensitive instrument.
Examples of disturbance sources are as given in Table 1.

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Table 1 Examples of disturbance sources
Type

Disturbance source

Operation frequency

External
disturbance(reference)

Solar radiation pressure
torqueTorque almost static

Residual magnetic torque
Gravity gradient torqueStationary
disturbance

Wheel for attitude control

10-200Hz

Gyro

155 Hz (in the case ofrotating at 9300 rpm)

Solar cell paddle drive
Mechanical scanningantenna

1-10HzCooler15-200Hz

Mission instrument drive
Transientdisturbance

Mission instrument drive
Solar cell paddle drive
Wheel zero-crossDeployment and extensionof instrument
Robot arm drive
Thermal snap

2.2

Influence and classification of disturbances(1) Classification by disturbance band
The attitude angle shall be the angle of the spacecraft. The pointing angle shall be thethree-axis angle of the instrument installed in the spacecraft. When the disturbance has a
low frequency and causes only rigid motion, the on-board instrument moves as one with thespacecraft. Thus, the attitude angle is the same as the pointing angle (low-frequency
domain). For a flexible structure attached to the spacecraft, when the disturbance frequency
reaches the domain which excites the vibration of the flexible structure, the flexible structure
and the coupled frame will vibrate. In the frequency domain (intermediate frequency
domain), the attitude angle of the body is influenced by the flexible structure. When the
instrument is installed in a rigid body, the pointing angle can be regarded as being equal tothe attitude angle. When the disturbance frequency is in the domain of a few dozens Hz or
more, in which the spacecraft and on-board instrument generate structural vibration(high-frequency domain), the pointing angle shall be determined mainly by the deformation
caused by the local vibration of the spacecraft and on-board instrument. In low andintermediate frequency domains, the influence of disturbance to the attitude system shall becontrolled. In the high-frequency domain, the structural characteristics and disturbance3

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propagation characteristics of the frame (including the layout of disturbance sources) shallbe controlled. The classification by the disturbance band (relationship between attitude
angle and pointing angle) is shown in Table 2.
Table 2 Classification by the disturbance band (relationship between attitude angle andpointing angle)
Frequency(Order)Low frequency
domainOrder of 0.01 Hz or
lessIntermediate frequency
domainOrder of 0.01 Hz - 10 Hz

High frequency domain
Order of 10 Hz or more
Attitude angle ≠ Pointing
angle

Attitude angle and Attitude angle =pointing angle
Pointing angle

Attitude angle = Pointing
angle

Remarks

The spacecraft structure
Local vibrations which
which can be regarded as atransfer the structure are therigid body is provided with aprincipal component ofdisturbance.
flexible structure. When the
on-board instrument is
In the frequency band, theinstalled on the flexible
pointing angle is determined
structure side, attitude angle ≠ by local deformation.
pointing angle.

The spacecraft canbe regarded as arigid body as awhole.

When pointing control is performed, the attitude
angle need not be equal to the pointing angle.

(2) Other classifications
Some spacecrafts which carry out missions in the stationary state steadily produce
disturbance, with an instrument like a reaction wheel. Such disturbance is referred to as
stationary disturbance. As mentioned in the previous section, stationary disturbance can beclassified and controlled in the frequency band. Of internal disturbances, disturbances
associated with the deployment and extension of solar cell paddles and antennas
temporarily (deployment disturbance) have a significant impact on the spacecraft attitude.
Such disturbances are referred to as “transient disturbances.” In the solar cell paddle drive,transient disturbances are regularly produced by the stepping motor. Disturbances shall be
regarded as transitional for pulse-by-pulse response. Disturbances shall be regarded asstationary when focusing on the macroscopic influence on pulse strings as a whole. In
intermittently-driven instrument, disturbance is transitional from a macroscopic viewpoint.
However, short-term behavior during driving must be regarded as a stationary disturbance.
Classification by waveform of disturbance is shown in Table 3.
Extremely micro disturbance shall be referred to as “micro-disturbance.” Micro-disturbanceis generally vibrational disturbance in many cases and is referred to as micro-vibration insome cases.

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Classification

Table 3 Classification by waveform of disturbanceFeatures and examples

Line spectrum
disturbance

Steady state frequency, harmonics and subharmonics of
instrument
Vibration source in which the transfer rate increases sharply
due to resonance produced by the structure and mount.

Random disturbance

Noise vibration, non-negligible background noise

Disturbance to be
regulated in time
domain(transitional)

Disturbance in which waveforms are regulated (torque or
angular momentum variation) in time domain

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2.3

Necessity for disturbance control

When mission requirements are evaluated and high pointing accuracy and pointing stability
are required in the initial phase of spacecraft development, disturbance control shall be
performed as part of the system design. When there is a large disturbance source inside thespacecraft, disturbance control must be performed as part of the system design. For
disturbance control to be performed as part of the system design, guidance with regard topointing accuracy, pointing stability requirements, and intensity of disturbance is as given
in Table 4.
When a device with sensitivity to the acceleration environment is installed in the spacecraft,
disturbance control must be performed in consideration of the acceleration environment.
When the on-board instrument must be under a micro-acceleration environment of the orderof 0.0001 m/s2 to 0.001 m/s2 (1 mG to 10 mG) or less, it is generally required that
disturbance control is to be performed.
It is required that large disturbance produced by the deployment of solar paddles is tobecontrolled to satisfy the basic functions and performance of the instrument and that theeffect on the spacecraft operation be evaluated and controlled. In such cases, it is required
to control only the operations associated with the deployment of the instrument such as
solar paddles. Disturbance control may be performed even though it is not indispensable aspart of the system design from the initial phase of the spacecraft development.
This design standard specifies the process of disturbance control to be performed as part ofthe system design from the initial phase of the spacecraft development.
Table 4 Guide on whether to perform disturbance control
Requirement

Value

When highaccuracy isrequired

Pointing
accuracy

0.01 to 0.001° or lessPointing
stability

0.001 to 0.0001° (specified time) or
less

When there is aseveredisturbance

MagnitudeofdisturbancesourceDisturbance which either equals or
surpasses 1/5 of the controlling force,
control torque and angular momentum
produced by the control instrument.

Acceleration
environment

0.0001 m/s2 to 0.001 m/s2 (1 mG to 10mG) or less6

Value shall be
determined dependingon the mission.

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2.4

Details of disturbance control

Disturbance control shall be performed as part of the system design and include the control
of disturbance sources, disturbance propagation (including instrument layout) anddisturbance sensitivity. The details are as follows. The relationship between operations isshown in Figure 2. Disturbance control operations are surrounded by thick dotted lines in the
figure.
Project management and quality
assurance

Control and systems engineering control

Disturbancerequirement
analysis

Disturbance
controlrequirement
setting

DesignSystem design(instrument layout)
Structural design
Instrument design(disturbance source andmission instrument)
Disturbance-reducing
instrument

Manufacturing

Disturbance
propagation test
(verification)

Disturbanceanalysis

Figure 2 Process flow
(1) Disturbance requirement analysis
Disturbance requirement analysis in which mission requirements or system
requirements are broken down
(2) Setting of disturbance control requirements
Basic disturbance control policy (including allocation to the following items)
Disturbance control items and disturbance requirements for disturbance-sensitive
instrument
Disturbance control items and disturbance requirements for disturbance sources
Requirements (frequency, band) for structure and control systems(3) Design related to disturbance instrument
The following designs shall be performed for instrument which acts as a disturbancesource and disturbance-sensitive instrument:
System design (instrument layout)
Structural design
Instrument design (disturbance source and mission instrument)
Disturbance-reducing instrument (such as isolator and damper)(4) Disturbance propagation test(5) Disturbance analysis

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3.

Process of disturbance control

Disturbance control processes differ depending on the spacecraft development phase. This
chapter explains the disturbance requirement analysis and disturbance control requirement
setting which are disturbance control processes in the initial development phase.
3.1

Disturbance requirement analysis in accordance with mission requirements

The process shall be started with disturbance requirement analysis. Possible disturbancesources and instrument (disturbance-sensitive instrument) which are likely to be affected by
disturbance shall be listed in accordance with the mission requirements.
(1) Listing disturbance sources
Disturbance sources are as shown in Table 1 in Paragraph 2. To facilitate control,
classification may be performed as shown in Table 2 and Table 3 in Paragraph 2.
(2) Listing disturbance-sensitive instrument
Various types of mission instrument shall be listed as disturbance-sensitive instrument.
3.2

Disturbance control requirement setting

Mission requirements are specified as baseline requirements for system disturbance control.
In concept designs, specific disturbance control requirements shall be specified as outputs
using the baseline requirements as basic inputs.
Input:
Mission requirements

Concept design phase

Output:Specific disturbance control
requirements

Figure 3 Input/output during concept design
The outputs should be put into document form to the extent possible. This standard
recommends that the output be documented as a project-specific disturbance control
standard or a disturbance control requirement (document).
For subsystem- and instrument-specific disturbance requirements, specific disturbancecharacteristic specifications shall be defined in accordance with the requirements specified
in the document. The design results in each phase shall be validated in a design review
meeting.

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4.

Disturbance control in each phase of spacecraft development

Concept and basic design phase
Disturbance control• System design and analysis (mission analysis,
pointing error analysis)• Identification of disturbance sources (instrument
selection)• Identification of disturbance-sensitive
instrument (instrument design, instrument
selection)• Structural design (including instrument layout)• Control band allocation (control system design)• Disturbance analysis
Disturbance source -> Propagation -> Influence
Evaluation of band allocation• Setting of disturbance control items and control
requirements(A disturbance control standard shall be establishedif necessary.)

Mission requirements
Pointing
Pointing accuracy• Pointing stability
requirements

System allocation• Error allocation• Stiffness requirements• Transfer characteristics
requirements• Band allocation
Disturbance control
requirements(Disturbance control standard)• Disturbance control item
• Disturbance requirements(sources, sensitivity, transfer
characteristics)• Disturbance interface
requirements• Verification plan

Detail specifications(disturbance requirements)
Disturbance interface
Mission requirements• Pointhing• Stability requirements
System design results• Control system• Structure
Detail specification• Disturbance requirements

Instrument design (disturbance
control)
Individual
disturbance test
(EM)

Disturbance control• System design and analysis (mission analysis,
pointing error analysis)• Instrument design (disturbance requirement
specification adjustment)• Structural design (including instrument
layout)• Structure disturbance transfer characteristic
analysis and test
• Disturbance analysis (evaluation of design
validity)• Review of disturbance control items andcontrol requirements(The disturbance control standard shall be
reviewed if necessary.)

Disturbancetest results

System allocation (review)• Error allocation• Stiffness requirements• Transfer characteristics
requirements• Band allocation
Disturbance control requirement(review)(Disturbance control standard
review)• Disturbance requirements(sources, sensitivity, transfer
characteristics)• Verification plan

Detail specifications (disturbancerequirements)
Disturbance interface specification

Detail design and manufacturing phase
Mission requirements• Pointing• Stability requirements
System design results• Control system• Structure
Detail specification• Disturbance requirements

Disturbance control (Evaluation of design
validity and PFT results based on the results oftests such as EM)• System design and analysis (mission
analysis, pointing error analysis)• Structure disturbance transfer characteristic
test• System disturbance evaluation test
• Disturbance analysis (evaluation of design
validity)• (The disturbance control standard shall be
reviewed if necessary.)

Instrument design (disturbance
control)

Individual
disturbancetest PFM

System allocation (review)• Error allocation• Stiffness requirements• Transfer characteristics
requirements• Band allocation
Disturbance control requirement(review)(Disturbance control standard)• Disturbance requirements(sources, sensitivity, transfer
characteristics)• Verification plan
Operation requirements (at theoccurrence of disturbance)

Disturban
ce testresults

Figure 4 Disturbance control flow in each phase of spacecraft development

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Figure 4 shows the flow of disturbance control in spacecraft design. The overview of
disturbance control process in each phase and precautions in performing disturbance
control are shown in the next chapter. This standard shows the overview of disturbance
control to be performed in the system. Similar control can be performed in subsystems andinstrument. The baseline requirements for disturbance control of subsystems andinstrument shall not be regarded as mission requirements and system requirements but asindividual disturbance requirements.
This chapter describes the disturbance control processes to be performed in each phase of
spacecraft design in accordance with the flow of spacecraft development. In spacecraft
development, a disturbance control plan shall be established with an eye to the input andoutput to disturbance control process.
4.1

Concept and preliminary design (conceptual design) phase(1) System design and analysis
It shall be required to break down the mission requirements and evaluate the basic
disturbance requirements (whether pointing error allocation assigned to disturbance causes
problems). If the on-board instrument has a significant source of disturbance, it is required toperform a brief evaluation of the effects on the missions and determine the policy forcontrolling disturbances. In the control policy, it is required to clearly identify the
instrument which must be free from the influence of the disturbance by imposing
operational restrictions such as paddle deployment.
In the policy for controlling disturbances, it is required to clarify the concept of what analyses
and tests are necessary for design and verification. It shall be required to estimate
resources including budgetary measures without missing large test instrument or events.
Depending on the circumstances, a BBM phase may be added (such as disturbancemeasurement test in the concept - preliminary design phase). (The policy for controlling
disturbances shall be organized as a disturbance control standard when needed.) Allocation
design is of importance in the phase of system design and analysis. It shall be required tocontrol the allocation and summation and define the aggregation method at the time ofallocation. When there are many newly developed items related to disturbance control andorbital verification is necessary, it is required to make an orbital verification plan in thisphase and develop orbital disturbance measuring instrument in the artificial spacecraft
development process.
(2) Understanding of disturbance sources and disturbance-sensitive instrument
First of all, it is necessary to check what on-board instrument is installed. In addition to bus
instrument such as wheels, it is required to review whether the mission-system instruments
such as coolers and compressors are possible sources of disturbance. It is necessary to
regard non-stationary disturbances, including deployment disturbances, as disturbancesources. For any instruments identified as disturbance sources, it is required to temporarily
specify the control items and values so that the instrument can be evaluated throughdisturbance analysis. When disturbance control standard is specified, it is required to10

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evaluate in line with the disturbance control standard whether the instruments and systems
meet the conditions. If the conditions are not met, feedback on the instrument design(including instrument selection) or system design (system allocation) shall be given. The
disturbance-sensitive instrument shall be understood similarly. It shall be required to checkbus-system instruments such as sensors (inertia sensors, optical sensors) andaccelerometers as well as mission instrument for disturbance sensitivity. For any
instruments identified as disturbance sensitive based on the investigation results, it isrequired, as in the case with disturbance sources, to temporarily specify the control items
and values so that the instrument can be evaluated through disturbance analysis. It is ofimportance, in this phase, to determine the interfaces between the disturbance sources anddisturbance-sensitive instrument and frame (including instrument-specific disturbance test
environment). The interface shall be a disturbance control item when needed.
(3) Structural design and allocation of control band
Based on the characteristics of disturbance sources and disturbance-sensitive instrument
understood in the previous section (including frequency characteristics), it is required in thisphase to perform a preliminary disturbance analysis (evaluate the disturbance influence),
instrument layout and band allocation to the control system. It is important in this phase to
estimate the disturbance transfer rate based on empirical values and specify structuraldesign requirements and instrument layout requirements as disturbance requirements.
When a disturbance control standard is specified, it is necessary to evaluate whether the
structural design results meet the stiffness requirements and damping requirements of the
disturbance control standard.
A control band shall be allocated to the control system to avoid interference with the resultsof the above structural analysis and disturbance characteristics (disturbance frequency) of
each instrument. As a goal, the control system should be separated from the disturbancesource by a decade or more when possible. If this goal cannot be achieved, the control
system shall be designed so that phase stability is ensured in the disturbance frequency
band.
(4) Disturbance analysis
The purpose of analysis is to evaluate the effect of disturbance and understand whether the
mission requirements can be satisfied. In this phase, enough information of disturbance
control items is not available in many cases. However, analysis shall be performed using
empirical values. If analysis results show that mission requirements are not satisfied,
feedback shall be given to the mission analysis and disturbance control standard. If analysis
results show that mission requirements are satisfied, the disturbance control items and thevalues are validated. Thus, disturbance control requirements will be specified.
(5) Setting of disturbance control requirements
The disturbance control items and the values established up to the previous section shall beorganized as disturbance requirements. For each disturbance control item, verification

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requirements up to the flight shall be included. When instrument design (instrument
selection) is not finished in this phase, it is required to establish a disturbance control
standard and perform instrument design and instrument selection continually.
(6) Design reviews
In design reviews (system requirement reviews (SRR)), the above process results(disturbance control) shall be evaluated for validity in line with the mission requirements. In
this phase, it is important to check whether the policy for controlling disturbances(disturbance control standard) is established according to the disturbance control level andwhether rational disturbance control items are specified.

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4.2

Basic design review (EM phase)(1) System design and analysis
According to the design results based on the disturbance control requirements specified in
the concept design and preliminary design phases (disturbance control standard), it isrequired to perform pointing error analysis in the system and evaluate the disturbance
control for validity in the basic design phase. When needed, the policy for controlling
disturbances (such as disturbance control standard) shall be reviewed.
(2) Subsystem/instrument design, specification adjustment
The subsystems (structure and control systems) and instrument shall be designed
according to the disturbance requirements specified in the previous phase. As part of
instrument design, it is required in the system to perform evaluation of whether the design of
instrument and subsystems is performed according to the disturbance control requirements(or disturbance control standard). When instrument selection is performed in this phase, it isrequired to perform evaluation of whether the disturbance characteristics of instrument are
valid in line with the disturbance control standard. In this phase, it is required to perform a
disturbance measurement test on some instruments to provide results with regard to systemanalysis and disturbance analysis. Accordingly, it is required to adjust the disturbancerequirement specifications and review the disturbance requirements if necessary.
(3) Disturbance characteristic test on instrument (test using EM)
Conducting testing to understand disturbance characteristics is technically difficult and large
scale. Thus, it is necessary to make an elaborate test plan considering the related fields. To
prevent discrepancies in interfaces, coordination shall be made properly with the systemside before testing is conducted. It is desirable that test results shall be evaluated in areview meeting by related divisions including the system division.
(4) Structure disturbance transfer characteristic test
When necessary, structure disturbance transfer characteristic tests shall be conducted(using a system structure model, etc.) on the results of structural designs in the system toevaluate the disturbance transfer characteristics. If the disturbance transfer characteristics
cannot meet the disturbance requirements, the structural design including the disturbanceisolator shall be reviewed. In conducting disturbance transfer characteristic tests in thesystem, disturbance sources that are hard to evaluate individually and disturbance-sensitive
instruments are installed in some cases to understand the disturbance transfer
characteristics of the structure including instrument. Conducting disturbance transfer
characteristic tests in the system is technically difficult and large scale. Thus, it is necessary
to make an elaborate test plan considering the related fields.
(5) Disturbance analysis
Various types of disturbance characteristic data (disturbance sources, disturbance transfer

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characteristics, disturbance sensitivity) as EM (including structure models) trial results areavailable in this phase. Using the data validity for disturbance control and system feasibilty
shall be checked. If analysis results show that mission requirements are not satisfied,
feedback shall be given with regard to the mission analysis and disturbance control standard.
If analysis results show that mission requirements are satisfied, the disturbance control
items and the values are validated. Thus, disturbance control requirements will be specified.
(6) Reviewing of disturbance control requirements
According to the process results up to the previous section, it is required, if necessary, toreview the disturbance control requirements as well as the disturbance-related requirements
for subsystems and individual instrument.
(7) Design reviews
The following items shall be reviewed:
 Subsystems and instrument PDR
It shall be required to perform validation of the disturbance characteristics ofsubsystems and instrument and interface parameters, and confirmation of the unit
verification/test plan. When any testing such as BBM is conducted, it is required toperform validation of the test results.
 System PDR
The validity of disturbance-related system design (including structural design andcontrol system design) shall be evaluated based on the results of system analysis
and disturbance analysis.
4.3

Detail design and manufacturing phase (PFM phase)

EM test results are available in this phase and thus it is possible to perform a realistic design
review to some extent. First, the design baseline shall be checked with respect todisturbance control items through CDR. Based on the results, shift to the manufacturingphase. When the EM test results require changes in the disturbance requirements, it isnecessary to perform validation of the changes through analysis. After the disturbancerequirements are found to be valid, shift to the manufacturing phase in accordance with the
disturbance control requirements (disturbance control standard) and individual disturbancerequirement specifications. Basically, similar processes mentioned in Section (2) of theprevious paragraph shall be performed in the following steps.
(1) System design and analysis
According to the design results and EM test results based on the disturbance control
requirements specified in the basic design phases (disturbance control standard), it isrequired to perform pointing error analysis in the system and evaluate the disturbance
control for validity in the detail design phase. When necessary, the policy for controlling
disturbances (such as disturbance control standard) shall be reviewed. When the policy
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JERG-2-152Amust be changed in this phase, design validation shall be performed again through EM.
When operational restrictions are imposed due to disturbance in this phase, information
shall be transferred to the operation phase as operation requirements (such as deployment
and antenna slew.
(2) Subsystem/instrument design, specification adjustment
It shall be required to perform disturbance design validation including EM and carry out
detail design of subsystems and instrument. As part of instrument design, it is required in thesystem to perform evaluation of whether the design of instrument and subsystems is
performed according to the disturbance control requirements (or disturbance control
standard).
(3) Disturbance characteristic test of subsystems and instrument (PFM test)
Conducting testing to understand disturbance characteristics is technically difficult and large
scale. Thus, it is necessary to make an elaborate test plan considering related fields. To
prevent discrepancy in interfaces, coordination shall be made properly with the system side
before conducting testing. It is desirable that test results be evaluated in a debriefing
session by related divisions including the system division.
(4) Structure disturbance transfer characteristic test and integrated disturbancecharacteristic test (PFM test)
When needed, structure disturbance transfer characteristic tests shall be conducted (using asystem structure model, etc.) on the results of structural designs in the system to evaluate
disturbance transfer characteristics. It shall be required to perform an integrated disturbancecharacteristic test on the system when needed and evaluate the disturbance control
performance for validity. Conducting disturbance characteristic tests in the system istechnically difficult and large scale. Thus, it is necessary to make an elaborate test planconsidering related fields.
(5) Disturbance analysis
Different types of disturbance characteristic data (disturbance sources, disturbance transfer
characteristics, and disturbance-sensitivity) as PFM test results are available in this phase.
Disturbance control shall be checked for validity and system feasibility using the data. If
analysis results show that mission requirements are not satisfied, feedback shall be given
with regard to the mission analysis and disturbance control standard.
(6) Reviewing of disturbance control requirements
According to the process results up to the previous section, it is required, if necessary, toreview the disturbance control requirements as well as the disturbance-related
specifications for subsystems and individual instrument.
(7) Design reviews
The following items shall be reviewed:
 Subsystems and instrument CDR

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JERG-2-152A

The instrument disturbance characteristics and interface parameters shall be checked forvalidity. The unit verification and test plan shall be checked. When any testing such as
BBM is conducted, it is required to perform validation of the test results.
 System CDR
The validity of disturbance-related system design (including structural design and control
system design) shall be evaluated based on the results of system analysis anddisturbance analysis.
 PQR
When the disturbance test is conducted through PFT, the design and operational
restrictions shall be evaluated for validity in accordance with the results. Operational
restrictions shall be reviewed if necessary.
4.4

Orbital operation phase

Occurrence of disturbance in orbit may lead to operational restrictions. First, it is necessary
to check whether the operational restrictions related to disturbances specified in the designphase are reflected in the operational procedures (including the time required before solar
paddle deployment disturbance and thermal snap-induced vibration are stable.).
In the orbit, it shall be confirmed that the conclusion in the design and manufacturing phases
are correct through checkout (such as initial inspection). Just in case, avoidance shall be
attempted in operation.
(1) Operational restrictions
Operational restrictions, such as stabilization of paddle deployment disturbance,
disturbance during antenna slew and thermal snap vibration, are imposed in many cases. It
shall be required to identify the disturbance-related operational restrictions and check thatthe restrictions are reflected in the operational procedures. The operational procedures shallbe checked for validity through operation analysis in light of the restrictions.
(2) Checkout
This is an operation check in the initial operation stage. In accordance with the telemetry
and system performance (circuit quality as for the communication system, shot image as forthe imaging system), the expected performance shall be checked for. If necessary,
operation for understanding disturbance characteristics shall be performed with theorbital-disturbance-measuring instrument installed. As a sensor measuring disturbance inthe orbit, IRU is used as bus instrument in many places. A dedicated accelerometer or jitter
sensor may be installed to measure disturbances associated with the deployment of
paddles and antennas. Conducting testing to understand disturbance characteristics in theorbit (checkout) is technically difficult. Thus, it is necessary to make an elaborate test planconsidering related fields.
(3) Nonconformance investigations
If the expected performance cannot be obtained, investigation shall be made as to whether
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disturbance is the cause of the nonconformance. It shall be required to check if the
instrument which is a probable disturbance source is turned on or off and in the case ofwheels, examine the correlation with the rotation speed. Avoidance shall be attempted inoperation.
(4) Obtaining and evaluating field proven data
Important on-orbit data can be obtained in some cases if an accelerometer or an attitude
sensor is used. If obtained and evaluated, such data will be useful in the next design.

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