ISO/TR 20218-1:2018

TECHNICAL ISO/TR
REPORT 20218-1
First edition
2018-08
Robotics — Safety design for
industrial robot systems —
Part 1:
End-effectors
Robotique — Conception de sécurité pour les systèmes de robots
industriels —
Partie 1: Organe terminal effecteur
Reference number
ISO/TR 20218-1:2018(E)
©
ISO 2018

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ISO/TR 20218-1:2018(E)

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ISO/TR 20218-1:2018(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Risk assessment . 2
4.1 General . 2
4.2 Limits of the end-effector(s) . 3
4.3 Hazard identification . 4
4.3.1 General. 4
4.3.2 Examples of hazards from end-effectors and workpieces . 4
4.4 Risk estimation . 4
4.5 Risk evaluation . 5
4.6 Residual risks . 5
5 Safety requirements and risk reduction. 5
5.1 General . 5
5.2 Risk reduction measures . 5
5.2.1 Shape and surfaces . . 5
5.2.2 Protective devices and safety-related functions . 5
5.2.3 Robot application design . 7
5.2.4 Risk reduction measures implemented by the user . 7
5.3 Safety-related control system performance . 7
5.4 Gripper end-effectors . 7
5.4.1 General. 7
5.4.2 Grasp-type grippers . 8
5.4.3 Vacuum grippers . 8
5.4.4 Magnet grippers . 8
5.5 Application-specific end-effectors . 9
5.5.1 General. 9
5.5.2 Examples of applications . 9
5.5.3 Risk reduction . 9
5.6 End-effectors for hand-guiding robots .10
5.6.1 General.10
5.6.2 Risk reduction .10
5.7 End-effector exchange systems (tool changers) .11
6 Verification and validation .11
7 Information for use .11
7.1 General .11
7.2 Instructions .11
Annex A (informative) Practical examples for end-effector risk assessment .13
Annex B (informative) Examples of gripper designs and their safety performance .18
Annex C (informative) Examples of hazards, their potential origins and consequences .19
Annex D (informative) Examples of hazards by function of the end-effector .22
Bibliography .24
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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 299, Robotics.
A list of all parts in the ISO 20218 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.
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ISO/TR 20218-1:2018(E)

Introduction
This document applies to industrial robot systems as described in ISO 10218-2:2011 and ISO/
TS 15066:2016.
This document provides guidance for end-effectors in robot systems, including collaborative
applications where a robot system and operators share the same workspace. In such collaborative
applications, the end-effector design is of major importance, particularly characteristics such as shapes,
surfaces and application function (e.g. clamping forces, residual material generation, temperature).
A comprehensive risk assessment is required by ISO 10218-2:2011. This document provides additional
guidance specific to end-effectors that can be helpful when performing the risk assessment in
accordance with ISO 10218-2:2011.
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TECHNICAL REPORT ISO/TR 20218-1:2018(E)
Robotics — Safety design for industrial robot systems —
Part 1:
End-effectors
1 Scope
This document provides guidance on safety measures for the design and integration of end-effectors
used for robot systems. The integration includes the following:
— the manufacturing, design and integration of end-effectors;
— the necessary information for use.
This document provides additional safety guidance on the integration of robot systems, as described in
ISO 10218-2:2011.
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.
ISO 10218-1:2011, Robots and robotic devices — Safety requirements for industrial robots — Part 1: Robots
ISO 10218-2:2011, Robots and robotic devices — Safety requirements for industrial robots — Part 2: Robot
systems and integration
ISO 11593, Manipulating industrial robots — Automatic end effector exchange systems — Vocabulary and
presentation of characteristics
ISO 12100:2010, Safety of machinery — General principles for design — Risk assessment and risk reduction
ISO 14539:2000, Manipulating industrial robots — Object handling with grasp-type grippers — Vocabulary
and presentation of characteristics
ISO/TS 15066:2016, Robots and robotic devices — Collaborative robots
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 12100, ISO/TS 15066:2016,
ISO 10218-1:2011, ISO 10218-2:2011, ISO 14539:2000, ISO 11593 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
compliant
exhibiting deformation of material or mechanism when subjected to a force
EXAMPLE Compliant linkage, compliant surface.
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Note 1 to entry: The reciprocal of compliant is stiff.
Note 2 to entry: Compliance is defined in ISO 8373:2012.
3.2
mechanical interface
end-effector (3.3) flange mounting surface at the end of the manipulator to which the end-effector is
attached
[SOURCE: ISO 8373:2012, 3.10, modified — The words “end-effector flange” have been added at the
start of the definition and the Note to entry has been deleted.]
3.3
end-effector
device specifically designed for attachment to the mechanical interface (3.2) to enable the robot to
perform its task
EXAMPLE Gripper (3.4), welding gun, spray gun.
Note 1 to entry: In this document, the term refers to end-effectors in robot systems.
Note 2 to entry: End-effectors are sometimes known as end-of-arm tooling (EOAT).
[SOURCE: ISO 8373:2012, 3.11, modified — The words “nut runner” have been deleted from the Example
and the Notes to entry have been added.]
3.4
gripper
end-effector (3.3) designed for grasping workpieces
Note 1 to entry: Grip, grasp, grasping and releasing are defined in ISO 14539:2000.
[SOURCE: ISO 8373:2012, 3.14, modified — The words “seizing and holding” have been replaced by
“grasping workpieces” in the definition and the Note to entry has been added.]
3.5
fixture
device used to fixate an item as part of the handling or assembling process in a robot system, but not as
an end-effector (3.3)
3.6
robot application
system comprising an industrial robot system [industrial robot, end-effectors (3.3), workpieces and
any machinery, equipment, devices, external auxiliary axes or sensors supporting the robot performing
its task] and any obstacle or object within the robot system workspace that has influence on the risk
assessment of the workspace
[SOURCE: ISO 10218-1:2011, 3.11, modified — Adapted from definition for “industrial robot system”.]
4 Risk assessment
4.1 General
This clause describes the actions and factors particularly relevant for the parts of a risk assessment
that address end-effectors in a robot application. In accordance with ISO 10218-2:2011, 4.3.1, the
risk assessment considers the risks for the entire robot application, including the robot, end-effector,
workpieces and fixture(s), over its whole lifecycle.
According ISO 10218-2:2011, the initial risk is assessed on the assumption that no risk reduction
measures have been applied. This includes modifications to existing robot applications.
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Potential contact situations (both intended and unintended) and the expected accessibility of a person
to interact with the end-effector(s) are considered.
The integrator consults with the user during the risk assessment and design of the workspace,
in accordance with ISO 10218-2:2011, 4.4.2. The purpose of this consultation is to ensure that all
reasonably foreseeable hazardous situations (task and hazard combinations) associated with the
robot cell are identified, including indirect interactions (e.g. persons having no tasks associated with
the system, but having exposure to hazards associated with the system). The integrator is responsible
for coordinating this participation and for selecting the appropriate end-effector(s) based on the
requirements of the application.
The results of the risk assessment are documented in accordance with ISO 12100:2010, 5.1 and Clause 7.
4.2 Limits of the end-effector(s)
The limits of the end-effector(s) should be considered when determining the limits for the robot
application as a whole (see ISO 10218-2:2011, 4.3.2). Some specific considerations for end-effectors can
include, but are not limited to the following:
a) use limits (description of functions, intended use and reasonably foreseeable misuse):
— automatic or manual;
— hand-guiding;
— collaborative or non-collaborative;
b) space limits:
— end-effector changing station;
— movement of the end-effector and workpiece;
— variation in dimensions of the end-effector and workpieces;
c) time limits:
— expected life for end-effector or parts of the end-effector or the grasped tool;
— end-effector exchange system exchange time;
NOTE 1 Deviations in the end-effector exchange time can indicate a fault in the robot system or the
end-effector exchange system.
d) other end-effector limits:
— acceptable workpiece shape/geometry;
— centre of gravity of workpiece(s);
— maximum/minimum payload;
— maximum/minimum grasping force (see ISO 14539:2000, 3.1.5);
— maximum/minimum suction of vacuum cup(s);
— maximum/minimum magnetic attraction properties;
— minimum friction between grasping surface (e.g. gripper fingers) and the workpiece;
— physical properties of workpiece, e.g. maximum/minimum size, compliance;
— maximum speed and/or acceleration;
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— environmental data, e.g. maximum/minimum temperature.
4.3 Hazard identification
4.3.1 General
In accordance with ISO 10218-2:2011, Clause 4, the risk assessment should identify all hazards related to
the intended use and the reasonably foreseeable misuse of the end-effector(s). End-effector hazards are
identified by a task-based risk assessment (see ISO 10218-2:2011, 4.4). In consultation with the user, the
integrator identifies all the tasks associated with the end-effector(s). These tasks could be associated
with an operating mode. End-effector usage is identified. In accordance with ISO 12100, examples of
factors which should be taken into consideration include but are not limited to the following:
a) transport;
b) assembly and installation or commissioning, e.g. process observation and monitoring;
c) setting, e.g. teaching and testing the robot program;
d) operation, e.g. routine operator intervention not requiring disassembly such as load/unload
operations, operator intervention such as clearing jams or similar simple corrections;
e) cleaning or maintenance, e.g. extended interaction with operator such as an adaptive fixture for
variable presentation of work piece or assembly;
f) fault-finding or troubleshooting;
g) dismantling or disabling.
An understanding of the interaction between end-effectors and other parts of the robot application is
needed for hazard identification.
While hazards are similar for collaborative and non-collaborative applications, the exposure of the
operator to these hazards can vary greatly. Consequently, the most relevant risks to consider can differ
depending upon whether the end-effector is used in a collaborative application or whether it is solely
operating in a non-collaborative environment.
4.3.2 Examples of hazards from end-effectors and workpieces
Examples of hazards that could be caused by end-effectors and workpieces include, but are not limited
to, those shown in Annex D.
4.4 Risk estimation
Risk is defined in ISO 12100:2010 as the combination of the probability of harm and the severity of that
harm. Annex A gives practical examples of risks associated with end-effectors.
Hazards associated with end-effectors and workpieces can be more or less severe than hazards
associated with the motion of the robot. Depending on the estimation of the risks associated with the
hazards of the end-effector and workpiece, safety functions used to control these hazards have a safety
performance level (PL) or a safety integrity level (SIL) in accordance with ISO 10218-2:2011, 5.2.
The risk level also depends upon whether the application uses a type of collaborative operation as
described in ISO 10218-2:2011, 5.11. The exposure of the operator is considered accordingly. The
hazards are the same for collaborative and non-collaborative applications, although the exposure can
vary greatly.
In accordance with ISO 12100, exposure is carefully considered for the design of the end-effector for
both collaborative and non-collaborative applications.
NOTE 1 ISO/TR 14121-2 gives examples of risk estimation tools.
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4.5 Risk evaluation
In accordance with ISO 12100, risk evaluation should be performed after risk estimation to verify
whether risks have been adequately reduced.
4.6 Residual risks
In accordance with ISO 10218-2:2011, 7.1, information about identified residual risks is included in the
information for use. See Clause 7.
5 Safety requirements and risk reduction
5.1 General
In accordance with ISO 10218-2:2011, end-effectors:
— are designed and constructed to comply with ISO 10218-2:2011, 5.3.10;
— comply with ISO 10218-2:2011, 5.2, for any safety-related control functions.
If intended for use in a power and force limited (PFL) collaborative application, a means to establish the
threshold limit values is provided in ISO/TS 15066:2016, Annex A.
NOTE 1 Power and force limited robots and robot systems are described in ISO 10218-1:2011, 5.10.5, and
ISO 10218-2:2011, 5.11.5.5. ISO/TS 15066:2016 contains additional information. The information contained in
this clause provides detailed guidance for designers of generic end-effectors, integrators selecting end-effectors
for robot applications as well as integrators designing end-effectors for specific robot applications.
NOTE 2 ISO 10218-2:2011 requires an end-effector to undergo a risk assessment for its specific application.
5.2 Risk reduction measures
5.2.1 Shape and surfaces
End-effector and fixture designs can incorporate design measures that reduce sharp edges to reduce
human contact forces or pressures (e.g. using smooth and compliant surfaces). End-effector mass can
be as low as practicable to minimize the forces or pressures associated with a transient contact (e.g.
minimizing momentum and kinetic energy). Padding and cushioning materials, as well as deformable
components, can reduce impact energy transfer.
Risk reduction measures are taken to minimize risks posed by sharp edges and prevent motion where
edges can result in unacceptable contact force(s) or pressure(s). Protective measures, such as increasing
edge radius, increasing surface area, modifying edge profiles (e.g. chamfer), or using different surface
materials, can be implemented. ISO/TS 15066:2016 provides further information on collaborative robot
applications.
The end-effector can also be designed to provide protection from hazards associated with the
workpiece(s).
5.2.2 Protective devices and safety-related functions
Protective devices and safety-related control systems built into, or associated directly with, the end-
effector can be used in some robot applications to reduce risk. Protective devices and safety control
systems can be, but are not limited to, the following:
a) force sensing (e.g. enhanced force sensing that is more sensitive than force sensing of the robot arm):
— measurement of applied forces on the surface(s) of the end-effector and corresponding
monitoring of the end-effector and/or robot as a safety function;
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b) end-effector path planning:
— if certain orientations of the gripper result in crush points and/or sharp edges being present
(e.g. a screw pointing towards a hole into which the robot screws it), robot movement in that
direction can be minimized and movement speed can be decreased to reduce risks; safety-rated
soft axis and space limiting functions can be used to monitor robot motion and end-effector
orientation and poses;
NOTE 1 ISO 13854 contains information about the minimum gaps to avoid crushing of parts of the
human body.
c) grip force:
— where the maximum grip force of the end-effector exceeds the risk assessment safety limits, the
grip force applied by the end-effector is reduced and monitored not to exceed acceptable levels
in accordance with ISO/TS 15066:2016;
d) speed monitoring:
— the robot speed for which the gripper is intended to be used is considered in the design of the
gripper;
— guidance is provided in ISO/TS 15066:2016 for collaborative applications;
— if the end-effector movement is controlled separately from the robot, the stop monitoring is
considered in addition to the robot system stopping;
e) presence sensing:
— a sensor (e.g. proximity, motion, image) can be used to detect a workpiece that has the potential
to initiate a sequence that could cause an injury to the operator;
— to reduce risk associated with contact to the moving end-effector during collaborative operation,
sensing means can be used to e.g. disable end-effector actuation when it is being touched or
when the operator is within a detection zone around the end-effector;
— these devices comply with the applicable parts of IEC 61496; integration of these devices is in
accordance with ISO 10218-2:2011, 5.2;
f) compliant link (e.g. a pliable link between the robot mechanical flange and the end-effector):
— compliant linkages and mechanisms in the gripper can absorb energy of contact; the transferred
force, motion, or energy achieved through compliant links are dissipated in a manner that
reduces the risk and does not introduce new risks;
— a sensor or safety function can be used to initiate a protective stop;
— for PFL robot applications, the effective force for initiating a protective stop is in accordance
with ISO/TS 15066:2016, 5.5.5;
NOTE 2 Collision protection devices, energy absorbing materials, springs can be used.
— the force or torque which an end-effector can apply to the environment can be limited, e.g. by
mechanical couplings that yield when a certain force or torque level is reached;
g) functional safety requirements:
— functional safety requirements in accordance with ISO 13849-1 are derived through the risk
reduction process;
— end-effector safety-related functions are designed in accordance with ISO 10218-2:2011, 5.2;
NOTE 3 Safety-related functions of the end-effector can be provided by either the robot or the end-
effector.
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h) emergency stop:
— in accordance with ISO 10218-2:2011, the emergency stop functions for the end-effector and for
the robot upon which it is mounted are in the same span of control;
— in accordance with ISO 13850, the actuation of this function stops or controls all hazards
associated with the robot and the end-effector as a minimum;
— IEC 60204-1 specifies the requirements about emergency stop categories;
— in the event of additional risks due to hazards in the remainder of the application, the risk
assessment can require that these be stopped or controlled as well by the same function.
5.2.3 Robot application design
Design changes to the robot application can be made to achieve adequate risk reduction. Design factors
that can be considered include, but are not limited to the following:
a) clearances between end-effector/fixture/workpiece and any obstructions (e.g.
...