ISO 5109:2023

Evaluation method for the resonance frequency of the multi-copter UA (unmanned aircraft) by measurement of rotor and body frequencies

This document provides a method for evaluating the resonance vibration frequency of the multi-copter unmanned aircraft (UA). This document specifies a method of designing the UA so as to avoid the resonance generated by the coincidence of the natural frequency of the UA body and the rotational frequency of the rotor. This document is applicable to multi-copter UA weighing less than 150 kg.

Méthode d'évaluation de la fréquence de résonance du multicoptère télépiloté par mesure des fréquences du rotor et du corps

General Information

• Status: Published
• Publication Date: 12-Jul-2023
• ICS: 49.020 - Aircraft and space vehicles in general
• Technical Committee: ISO/TC 20/SC 16 - Unmanned aircraft systems
• Drafting Committee: ISO/TC 20/SC 16/WG 5 - Testing and evaluation
• Current Stage: 6060 - International Standard published
• Start Date: 13-Jul-2023
• Due Date: 09-Jun-2023
• Completion Date: 13-Jul-2023

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 5109
First edition
2023-07
Evaluation method for the resonance
frequency of the multi-copter UA
(unmanned aircraft) by measurement
of rotor and body frequencies
Méthode d'évaluation de la fréquence de résonance du multicoptère
télépiloté par mesure des fréquences du rotor et du corps
Reference number
ISO 5109:2023(E)
© ISO 2023

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ISO 5109:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
  © ISO 2023 – All rights reserved

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ISO 5109:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test method . 2
4.1 Test setup . 2
4.1.1 General . 2
4.1.2 Hammering method . . 2
4.1.3 Excitation table method . 4
4.2 Concept of an operation frequency . 4
5 Analysis of natural frequency and operation frequency . 5
5.1 Natural frequency . 5
5.1.1 General . 5
5.1.2 Natural frequency measurement. 6
5.2 Operation frequency. 6
5.2.1 Operation frequency measurement . 6
5.2.2 Thrust force measurement . 6
6 Evaluation of resonance .7
6.1 General . 7
6.2 Operating frequency and natural frequency overlapping . 7
Bibliography . 9
iii
© ISO 2023 – All rights reserved

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ISO 5109:2023(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles,
Subcommittee SC 16, Unmanned aircraft systems.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
  © ISO 2023 – All rights reserved

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ISO 5109:2023(E)
Introduction
This document defines the correlation between the excitation frequency caused by rotor rotation and
the resonance frequency of the main body in the design of the multi-copter UA (unmanned aircraft), and
suggests the evaluation method to define the design requirements of the multi-copter UA to prevent
damage due to resonance.
Typical applications for evaluation of resonance of the UA are:
a) measuring the natural frequency of the UA;
b) measuring the thrust forces and the rotational frequency of the rotor;
c) determining the modal properties of the UA (natural frequency, damping and mode shape);
d) checking the resonance between the natural frequency of main body and the rotational frequency
of the rotor.
v
© ISO 2023 – All rights reserved

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INTERNATIONAL STANDARD ISO 5109:2023(E)
Evaluation method for the resonance frequency of the
multi-copter UA (unmanned aircraft) by measurement of
rotor and body frequencies
1 Scope
This document provides a method for evaluating the resonance vibration frequency of the multi-
copter unmanned aircraft (UA). This document specifies a method of designing the UA so as to avoid
the resonance generated by the coincidence of the natural frequency of the UA body and the rotational
frequency of the rotor.
This document is applicable to multi-copter UA weighing less than 150 kg.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
IEC 60068-2-6, Environmental testing – Part 2-6: Tests – Test Fc: Vibration (sinusoidal)
IEC 60068-2-64, Environmental testing - Part 2-64: Tests - Test Fh: Vibration, broadband random and
guidance
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
operating frequency range
rotation frequency span between the lowest frequency to the highest frequency of an unmanned
aircraft (UA) to fly
3.2
natural frequency
frequency or rate at which an unmanned aircraft (UA) vibrates naturally when disturbed
Note 1 to entry: The natural frequency changes when the mass distribution (e.g. adding a payload) changes, it is
measured with the added payload.
3.3
resonant frequency
phenomenon in which an external force or a vibrating system forces another system around it to vibrate
with greater amplitude at a specified frequency of operation
1
© ISO 2023 – All rights reserved

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ISO 5109:2023(E)
3.4
frequency response function
function that represents the relationship between an input signal and an output signal in the frequency
domain
3.5
FFT
fast Fourier transform
algorithm that computes the discrete Fourier
...

DRAFT INTERNATIONAL STANDARD
ISO/DIS 5109
ISO/TC 20/SC 16 Secretariat: ANSI
Voting begins on: Voting terminates on:
2022-08-04 2022-10-27
Evaluation method for the resonance frequency of the
multi-copter UA by measurement of rotor and body
frequencies
ICS: 49.020
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
This document is circulated as received from the committee secretariat.
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 5109:2022(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. © ISO 2022

---------------------- Page: 1 ----------------------
ISO/DIS 5109:2022(E)
DRAFT INTERNATIONAL STANDARD
ISO/DIS 5109
ISO/TC 20/SC 16 Secretariat: ANSI
Voting begins on: Voting terminates on:

Evaluation method for the resonance frequency of the
multi-copter UA by measurement of rotor and body
frequencies
ICS: 49.020
COPYRIGHT PROTECTED DOCUMENT
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
© ISO 2022
THEREFORE SUBJECT TO CHANGE AND MAY
This document is circulated as received from the committee secretariat.
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
NOT BE REFERRED TO AS AN INTERNATIONAL
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on STANDARD UNTIL PUBLISHED AS SUCH.
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
IN ADDITION TO THEIR EVALUATION AS
or ISO’s member body in the country of the requester. BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
ISO copyright office
USER PURPOSES, DRAFT INTERNATIONAL
CP 401 • Ch. de Blandonnet 8
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
CH-1214 Vernier, Geneva
POTENTIAL TO BECOME STANDARDS TO
Phone: [phone]
WHICH REFERENCE MAY BE MADE IN
Reference number
Email: [e-mail]
NATIONAL REGULATIONS.
Website: www.iso.org ISO/DIS 5109:2022(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
Published in Switzerland
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
ii
  © ISO 2022 – All rights reserved
PROVIDE SUPPORTING DOCUMENTATION. © ISO 2022

---------------------- Page: 2 ----------------------
ISO/DIS 5109:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test method . 2
4.1 Concept of test method . 2
4.1.1 Hammering method . . 2
4.1.2 Excitation table method . 3
4.2 Concept for an operation frequency . 4
5 Measurement of natural frequency and operation frequency . 4
5.1 Natural frequency . 4
5.1.1 Natural frequency measurement. 5
5.2 Operation frequency. 5
5.2.1 Operation frequency measurement . 5
5.2.2 Thrust force measurement . 5
6 Evaluation of resonance .6
6.1 Operating frequency and natural frequency overlapping . 6
iii
© ISO 2022 – All rights reserved

---------------------- Page: 3 ----------------------
ISO/DIS 5109:2022(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 20, Subcommittee SC 16, Testing and
Evaluation.
A list of all parts in the ISO ##### series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
  © ISO 2022 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/DIS 5109:2022(E)
Introduction
This standard defines the correlation between the excitation frequency caused by rotor rotation and the
resonance frequency of the main body in the design of the multi-copter UA, and suggests the evaluation
method to define the design requirements of the multi-copter UA to prevent damage due to resonance.
Typical applications for evaluation of resonance of UA are ;
a) measuring the natural frequency of UA ;
b) measuring the thrust forces and rotor rotating frequency ;
c) determining the modal properties of UA(natural frequency, damping and mode shape) ;
d) checking the resonance between main body and rotor rotating frequency ;
e) evaluation of the effect on UA after resonant frequency analysis.
v
© ISO 2022 – All rights reserved

---------------------- Page: 5 ----------------------
DRAFT INTERNATIONAL STANDARD ISO/DIS 5109:2022(E)
Evaluation method for the resonance frequency of the
multi-copter UA by measurement of rotor and body
frequencies
1 Scope
This standard provides a method for evaluating the resonance vibration frequency of multi-copter UA
only. The frequency of the rotor means the frequency within the operating frequency range, and the
frequency of the main body means the global mode frequency. This standard specifies a method to
avoid design of UA that the resonance occurs generated by the coincidence of the natural frequency of
the UA body and the rotational frequency of the rotor.
This standard relates to multi-copter UA weighing less than 150kg.
2 Normative references
ISO 21384-2:2019, Unmanned aircraft systems – Part 2 : Product systems
ISO 21384-3:2019, Unmanned aircraft systems — Part 3: Operational procedures
ISO 21384-4:2019, Unmanned aircraft systems – Part 4 : Vocabulary
ISO 21895:2020, Categorization and classification of civil unmanned aircraft systems
ISO 7626-2:2015, Mechanical vibration and shock — Experimental determination of mechanical mobility
— Part 2: Measurements using single-point translation excitation with an attached vibration exciter
ISO 7626-5:2019, Mechanical vib
...