ISO 5110:2023

Test method for flight stability of a multi-copter unmanned aircraft system (UAS) under wind and rain conditions

This document specifies the procedures for testing flight stability of a multi-copter unmanned aircraft system (UAS) and is applicable to multi-copter type UAS that can take-off and land vertically. A commercial multi-copter UAS weighing over 250 g to less than 150 kg is discussed in this document. Further, this document is applicable to military and civilian multi-copter UAS. However, quantitatively specific stability criteria for the test are not specified in this document.

Méthode d'essai relative à la stabilité en vol d'un multicoptère télépiloté dans des conditions de vent et de pluie

General Information

• Status: Published
• Publication Date: 20-Aug-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: 21-Aug-2023
• Due Date: 04-Jun-2023
• Completion Date: 21-Aug-2023

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 5110
First edition
2023-08
Test method for flight stability of
a multi-copter unmanned aircraft
system (UAS) under wind and rain
conditions
Méthode d'essai relative à la stabilité en vol d'un multicoptère
télépiloté dans des conditions de vent et de pluie
Reference number
ISO 5110:2023(E)
© ISO 2023

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ISO 5110:2023(E)
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© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ISO 5110:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General principles . 2
4.1 Test purpose . 2
4.2 Test condition . 2
4.3 Test apparatus. 2
4.4 Test method . 3
4.4.1 General . 3
4.4.2 Take-off and landing stability test under wind. 5
4.4.3 Take-off and landing stability test under wind and rainfall . 5
4.4.4 Six-directional flight stability test under wind . 5
4.4.5 Six-directional flight stability test under wind and rainfall . 5
4.4.6 Flight stability test under wind during a 360° rotational flight . 5
4.4.7 Flight stability test under wind and rainfall during a 360° rotational flight . 5
4.5 Measurement system . 5
5 Test process . 6
5.1 Preparatory procedure . 6
5.2 Test procedure . 6
5.2.1 Take-off landing stability under wind . 6
5.2.2 Take-off landing stability under wind and rainfall . 6
5.2.3 Six-directional flight stability under wind . 7
5.2.4 Six-directional flight stability under wind and rainfall . 8
5.2.5 360° rotational stability under wind . 9
5.2.6 360° rotation stability under wind and rainfall . 9
6 Examination and evaluation . 9
Annex A (informative) Examples of the multi-copter UAS flight stability test .10
Annex B (informative) Example of the report format for the multi-copter UAS flight
stability test .18
Bibliography .20
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ISO 5110:2023(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
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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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use
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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.
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ISO 5110:2023(E)
Introduction
Multi-copter unmanned aircraft (UA) find a wide variety of applications ranging from individual
hobbies, such as image capture and racing, to a rapidly increasing number of commercial purposes,
such as precision farming, delivery, and inspection. Multi-copter UA control and flight dynamics are
unique relative to those of well-known fixed and rotary wing configurations, and therefore must
be fully understood to ensure their safe usage and integration into commercial applications. This
document identifies a manner of determining system level flight stability by evaluating the multi-copter
UA’s automated control system capability to maintain its spatial position when faced with a variety of
simulated temperature, wind, gust, rainfall and ice conditions. The test method for the flight stability
of the multi-copter unmanned aircraft system (UAS) provides the test condition, procedure, report
format, etc. The principal advantage of the test method is its ability to evaluate the flight stability of
a multi-copter UAS considering actual flight conditions. All tests are performed considering real-time
flight status. The purpose of the test method is to evaluate and improve the flight stability of a multi-
copter UAS through experiments conducted under various environmental conditions.
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INTERNATIONAL STANDARD ISO 5110:2023(E)
Test method for flight stability of a multi-copter unmanned
aircraft system (UAS) under wind and rain conditions
1 Scope
This document specifies the procedures for testing flight stability of a multi-copter unmanned aircraft
system (UAS) and is applicable to multi-copter type UAS that can take-off and land vertically. A
commercial multi-copter UAS weighing over 250 g to less than 150 kg is discussed in this document.
Further, this document is applicable to military and civilian multi-copter UAS. However, quantitatively
specific stability criteria for the test are not specified in this document.
2 Normative references
There are no normative references in this document.
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
flight stability
ability to maintain the parameters of motion (linear and angular positions, speed) within predefined
tolerances and time when exposed to external disturbances
Note 1 to entry: Flight stability of a multi-copter UAS can be defined as its spatial precision of take-off, landing,
hovering and moving intended by a pilot or autopilot flight program used while being subjected to various flight
environments.
3.2
manual mode
mode in which an aircraft flies with complete autopilot stabilization of three axes of motion (pitch,
roll, and yaw), heading hold (via a compass), height hold (via barometric pressure sensor), and lateral
position hold (via GNSS or optically)
Note 1 to entry: The pilot commands the aircraft to move to a different height or lateral position as required.
Once the pilot control input is released, autopilot stabilizes the UA.
3.3
autopilot mode
mode in which an aircraft moves according to pre-programmed waypoints (vertically or horizontally)
and/or performs take-off or landing operations without any pilot input
Note 1 to entry: Flight control for the entire duration or for some parts of the flight is performed without a pilot.
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ISO 5110:2023(E)
4 General principles
4.1 Test purpose
The purpose of this test method is to measure the flight stability of a multi-copter UAS under given
operational conditions. To check the overall performance of each component of the multi-copter UAS,
such as propulsion, control, and battery management systems, an actual test flight of the multi-copter
UAS in a test device is performed. For flight stability evaluations of the multi-copter UAS, actual flight
conditions are considered, while all tests are performed inflight. The proposed stability test method and
device are expected to satisfy numerous commercial multi-copter UAS manufacturers and developers
by evaluating and improving the flight stability of their multi-copter UASs via experimental results.
4.2 Test condition
Flight stability measurements of a multi-copter UAS are performed in a test device especially designed
for simulating flight conditions and measuring real-time spatial position of a multi-copter UA. In the
test device, the multi-copter UA is capable of flying under several environmental conditions, such as
temperature (from −20 °C to 50 °C), wind speed (from 0 m/s to 30 m/s), rain fall (from 0 mm/h to
20 mm/h, from 0 °C to 50 °C), ice (from −20 °C to 0 °C) and gust. Testing relative to rainfall does not
assess the ingress protection (water) of the multi-copter UAS. Particularly, position data of the multi-
copter UA during the stability test are stored to evaluate flight stability. The test conditions are adjusted
depending on the purpose and operation condition of the multi-copter UAS because not every multi-
copter UA test requires a high cost test device or a long test period. Based on the instructions of the
manufacturer, battery safety care and storage should also be considered. For instance, battery should
be kept in warm conditions (0 °C at least) before conducting the test to ensure its proper functioning.
The test should be performed considering the flight conditions according to the various payloads
attached to the multi-copter UA.
4.3 Test apparatus
The test apparatus consists of devices capable of generating wind, gust, rain and measuring the
position of multi-copter UA during flight stability test. If the test apparatus satisfies the required
experimental conditions, it can be installed indoors or outdoors, but the environment should be free
from electromagnetic interference. To secure stable global positioning system (GPS) signal strength,
the roof and side walls of the test apparatus are built of a material with good GPS signal transmittance.
A laminar (or turbulent) wind generator is used to maintain constant wind speed and quality to
reproduce a natural environment during the flight stability test. The test section volume (width ×
height × depth) is determined by the size (diagonal length from rotor to rotor) of the multi-copter UA.
A rainfall device using specified equipment, such as multiple nozzles, is used to spray water. The wind
gust test should be performed using various controllable wind gust generation methods, such as an
[1]
oscillating vane gust generator. The wind speed difference for gust should be adjustable through
the gust generating device according to the wind speed of the test condition in progress. A three-
dimensional position measuring device is used to measure the real-time position of the multi-copter
UA using various measuring instruments (motion capture camera, IR camera, video camera, ultra-sonic
sensor, UWB, etc). When video-recording-based measurement systems are considered, grid markers
should be included on the walls and floor of the test apparatus. The example general specifications of
the test device are presented in Table 1. The wind nozzle size should be such that the target air velocity
can be set according to the size of the multi-copter UA and test area. Generally, the wind nozzle size
should be at least 1,5 times larger than of the multi-copter UA.
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ISO 5110:2023(E)
Table 1 — The example specification of test device for commercial multi-copter UAS (250 g to
25 kg)
Item Contents
Wind nozzle size 4 m × 4 m
Wind speed 0 m/s to 30 m/s
Wind gust generation method Oscillating vane gust generator
Test section size 8 m × 8 m × 12 m (w × h × d)
Rainfall simulation system 20 mm/h (max.)
Measuring system for 3-dimensional position of multi-copter UA centimetre grade error
4.4 Test method
4.4.1 General
The flight stability test evaluation method consists of six cases as specified in 4.4.2 to 4.4.7. In the first
test case, take-off and landing spatial precision measurements are performed under the specified
wind speed within predefined sampling time. In the second test case, rainfall conditions are added
to the first test case before evaluation. For in-flight stability measurements under the specified wind
speed within the predefined sampling time, the third test case is used. The fourth test case is used
to measure the flight stability with added rainfall conditions to the third test case. In the fifth test
case, 360° rotational flight precision measurements are performed under the specified wind speed
within predefined sampling time. In the sixth test case, rainfall conditions are added to the fifth test
case before evaluation. The flight stability for take-off and landing is performed while adjusting the
wind speed, gust condition (wind speed difference), rainfall amount and measuring the flight path
deviation. The flight stability for the spatial motion for six directions (up, down, left, right, forward,
and backward) and the rotational motion for 360° are evaluated while adjusting the wind speed,
gust condition (wind speed difference), rainfall amount and measuring flight path deviations. The six
test cases for evaluating the flight stability of the multi-copter UAS are considered to satisfy various
evaluation requests as much as possible. Therefore, it is not mandatory to perform all test cases; the
tester and the requester select the suitable test case according to relevant requirements. Each flight
stability evaluation is determined by the flight path deviation between the desired and measured
values using a measuring system with centimetre-level positioning accuracy. The concept of the overall
test method and the considered conditions are shown in Figure 1 and Table 2, respectively.
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ISO 5110:2023(E)
a) Take-off and landing stability b) Six-directional flight stability c) Six-directional flight stability
under wind under wind under wind and rain
Key
1 test section
2 wind nozzle
3 rainfall nozzle
Figure 1 — The test method for evaluation of the flight stability
Table 2 — The test method and condition for flight stability evaluation
Position
Test item Multi-copter UA motion Test condition
measurement
Temperature: −20 °C to 50 °C
Take-off and landing stability
Vertical take-off ↔ landing
under wind(gust)
Wind speed: 1 m/s to 30 m/s
Temperature: −20 °C to 50 °C
Take-off and landing stability
under wind(gust) and rain- Vertical take-off ↔ landing Wind speed: 1 m/s to 30 m/s
fall
Rain fall: 0 mm/h to 20 mm/h
Temperature: −20 °C to 50 °C
Six-directional flight stability
Real time
Six-directional flight
under wind(gust)
measuring
Wind speed: 1 m/s to 30 m/s
three-dimen-
Temperature: −20 °C to 50 °C
Six-directional flight stability sional position
under wind(gust) and rain- Six-directional flight Wind speed: 1 m/s to 30 m/s of
fall multi-copter UA
Rain fall: 0 mm/h to 20 mm/h
Temperature: −20 °C to 50 °C
360° rotation flight stability
360° rotational flight
under wind(gust)
Wind speed: 1 m/s to 30 m/s
Temperature: −20 °C to 50 °C
360° rotation flight stabil-
ity under wind(gust) and 360° rotational flight Wind speed: 1 m/s to 30 m/s
rainfall
Rain fall: 0 mm/h to 20 mm/h
[2]
The range of wind speed is set from light air to violent storm based on the Beaufort wind force scale,
while the range of rainfall intensity is set from light to heavy rain based on the rainfall intensity
[3]
categorization. The maximum wind speed and rain fall rate can be determined by the requester.
The considered maximum wind speed and rainfall rate of 30 m/s and 20 mm/h, respectively, are not
mandatory. To ensure sufficient intensity of rainfall, droplets of size ranging from 0,5 mm to 4,5 mm
[4]
are considered. Most of gust generation methods create a wind speed difference for gust by adjusting
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ISO 5110:2023(E)
the direction of the wind generated by wind generator. Therefore, the test procedure is to adjust the
wind speed difference for gust after adjusting the wind speed. All test cases include a step to adjust the
wind speed difference for gust; but if a gust test is not performed, this step can be skipped.
4.4.2 Take-off and landing stability test under wind
According to the test purpose, the wind speed and temperature should be adjusted from 1 m/s to 30 m/s
and −20 °C to 50 °C, respectively. Spatial deviations between the desired and actual paths should be
measured during take-off and landing operations. The stability criterion is that the multi-copter UA
should land in an upright position within a set distance from the take-off position.
4.4.3 Take-off and landing stability test under wind and rainfall
According to the test purpose, the wind speed, temperature, and rainfall intensity should be adjusted
from 1 m/s to 30 m/s, −20 °C to 50 °C, and 0 mm/h to 20 mm/h, respectively. Spatial deviations between
the desired and actual paths should be measured during take-off and landing operations. The stability
criterion is that the multi-copter UA should land in an upright position within a set distance from the
take-off position.
4.4.4 Six-directional flight stability test under wind
According to the test purpose, the wind speed and temperature should be adjusted from 1 m/s to
30 m/s, and −20 °C to 50 °C, respectively. Spatial deviations between the desired and actual paths
should be measured during each six-directional flight, at least 1 m from the start position. The stability
criterion is that the multi-copter UA can stay within a set three-dimensional boundary. The wind speed
at which the multi-copter UA can no longer remain with the set boundary should be considered.
4.4.5 Six-directional flight stability test under wind and rainfall
According to the test purpose, the wind speed, temperature, and rainfall intensity should be adjusted
from 1 m/s to 30 m/s, −20 °C to 50 °C, and 0 mm/h to 20 mm/h (mixed conditions), respectively. Spatial
deviations between the desired and actual paths should be measured during each six-directional flight,
at least 1 m from the start position. The stability criterion is that the multi-copter UA can stay within
a set three-dimensional boundary. The wind speed at which the multi-copter UA can no longer remain
with the set boundary should be considered.
4.4.6 Flight stability test under wind during a 360° rotational flight
According to the test purpose, the wind speed and temperature should be adjusted from 1 m/s to
30 m/s, and −20 °C to 50 °C, respectively. Spatial deviations between the desired and actual paths
should be measured during a 360° rotational flight. The stability criterion is that the multi-copter UA
can stay within a set three-dimensional boundary. The wind speed at which the multi-copter UA can no
longer remain with the set boundary should be considered.
4.4.7 Flight stability test under wind and rainfall during a 360° rotational flight
According to the test purpose, the wind speed, temperature, and rainfall intensity should be adjusted
from 1 m/s to 30 m/s, −20 °C to 50 °C, and 0 mm/h to 20 mm/h (mixed conditions), respectively. Spatial
deviations between the desired and actual paths should be measured during a 360° rotational flight.
The stability criterion is that the multi-copter UA can stay within a set three-dimensional boundary.
The wind speed at which the multi-copter UA can no longer remain with the set boundary should be
considered.
4.5 Measurement system
Any type of spatial precision measurement system, such as those using ultrasound, ultra-wideband,
precision motion capture camera, and video recording, that considers flight motion of a multi-copter
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ISO 5110:2023(E)
UA can be used for measurements. The measurement system should measure the position of the multi-
copter UA using a centimetre holder.
5 Test process
5.1 Preparatory procedure
The preparatory procedure should be performed as follows.
a) Check calibration status of measurement devices (wind speed measurement probe, position
measurement device, etc.).
b) Set to a predefined temperature.
c) Measure and record atmospheric pressure.
d) Prepare and check the multi-copter UA.
e) Activate the ground control system to communicate with the multi-copter UA.
f) Power on the multi-copter UA.
g) Establish a multi-copter UA communication network with the ground control system.
h) Check and monitor the status (gyroscope, GPS, compass sensor, etc) of the multi-copter UA.
5.2 Test procedure
5.2.1 Take-off landing stability under wind
The test procedure shall be performed as follows.
a) Adjust the wind speed from 0 (m/s) to the targeted velocity (m/s).
b) Adjust the wind speed difference 0 (%, m/s) to the targeted wind speed difference (%, m/s) for the
wind gust generation. (If the wind gust test is not performed, this step is skipped.)
c) Record the position and posture data obtained by the three-dimensional measurement system.
d) Record the position and posture velocity data obtained by the three-dimensional measurement
system.
e) Save the log file obtained by the multi-copter UA.
f) Perform take-off under wind in manual or autopilot mode.
g) Perform landing under wind in manual or autopilot mode.
h) Adjust the wind speed from the targeted velocity (m/s) to 0 m/s.
5.2.2 Take-off landing stability under wind and rainfall
The test procedure should be performed as follows.
a) Adjust the wind speed from 0 m/s to the targeted velocity (m/s).
b) Adjust the wind speed difference 0 (%, m/s) to the targeted wind speed difference (%, m/s) for the
wind gust generation. (If the wind gust test is not performed, this step is skipped.)
c) Adjust the rainfall intensity from 0 mm/h to the targeted rainfall rate (mm/h).
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ISO 5110:2023(E)
d) Record the position and posture data obtained using the three-dimensional measurement system.
e) Record the position and posture velocity data obtained using the three-dimensional measurement
system.
f) Save the log file obtained by the multi-copter UA.
g) Perform take-off under wind in manual or autopilot mode.
h) Perform landing under wind in manual or autopilot mode.
i) Adjust the wind speed from the targeted velocity (m/s) to 0 m/s.
j) Adjust the rainfall intensity from the targeted rainfall rate (mm/h) to 0 mm/h.
5.2.3 Six-directional flight stability under wind
The test procedure should be performed as follows.
a) Adjust the wind speed from 0 m/s to the targeted velocity (m/s).
b) Adjust the wind speed difference 0 (%, m/s) to the targeted wind speed difference (%, m/s) for the
wind gust generation. (If the wind gust test is not performed, this step is skipped.)
c) Record the position and posture data obtained using the three-dimensional measurement system.
d) Record the position and posture velocity data obtained using the three-dimensional measurement
system.
e) Save the log file obtained by the multi-copter UA.
f) Perform take-off under wind in manual or autopilot mode.
g) Record the position and posture data obtained using the three-dimensional measurement system.
h) Record the position and posture velocity data obtained using the three-dimensional measurement
system.
i) Save the log file obtained by the multi-copter UA.
j) Perform up-down flight motion under wind in manual or autopilot mode.
k) Record the position and posture data obtained using the three-dimensional measurement system.
l) Record the position and posture velocity data obtained using the three-dimensional measurement
system.
m) Save the log file obtained by the multi-copter UA.
n) Perform leftward–rightward flight motion under wind in manual or autopilot mode.
o) Record the position and posture data obtained using the
...