2 RELATED WORK
2.1 Safety and Risk Assessment
There are various standards that serve as guidelines
for safety assessment and risk reduction.
ISO 12100 contains comprehensive guidelines for
the risk assessment and risk reduction of machines
and industrial robots (iso, 2010). The standard fo-
cuses on the identification of potential hazards, the
assessment and evaluation of risks and the implemen-
tation of suitable risk reduction measures.
Another relevant standard is ISO 10218, which
deals with the safety of industrial robots and robot
systems (iso, 2011). It defines specific requirements
for the design, integration and implementation of
robotic systems to ensure safe operations in industrial
environments. It also contains special guidelines for
risk assessment in human-robot interaction.
ISO 31000 describes principles and guidelines for
risk management in various industries (iso, 2018).
Although the standard does not refer specifically to
robotics, it provides guidance on identifying, assess-
ing and mitigating risks in complex industrial pro-
cesses. It also describes a comprehensive approach
to risk management that is applicable to different or-
ganizational contexts.
2.2 Safety and Risk Assessment
Methods
In industrial safety and risk assessment, various meth-
ods are used to ensure the safety and reliability of sys-
tems. These methods can be classified into two princi-
pal categories: bottom-up and top-down approaches.
In contrast to the bottom-up approach, which ini-
tially identifies safety risks at the most granular level
and subsequently aggregates these risks, the top-down
method initiates the process at the system level and
progressively breaks down the risks into more specific
categories. The approaches can be used individually
or in combination to analyze potential risks.
Probably the most frequently used bottom-up
method is FMEA, which guarantees that potential
faults within a system are found and the impact of
those faults on the overall performance of the system
is analyzed. FMEA improves the robustness of the
system by highlighting important elements and pro-
cedures which need tighter control. (Liu et al., 2019).
Another well-known technique is Hazard and Op-
erability Analysis (HAZOP). The method deals sys-
tematically with process deviations and their possible
consequences for identifying and assessing potential
hazards that exist within the industrial process. HA-
ZOP makes sure all possible risks are accounted for
and managed accordingly. (Reddy, 2015)
Aside from the bottom-up methods, there are also
well-known methods such as Fault Tree Analysis
(FTA), which follows a top-down approach to esti-
mate the probability of certain failures in the system.
It makes logical interconnections between the possi-
ble causes that might lead to system-wide failure and
calculates their probability of occurrence, a structured
way of understanding and mitigating risks. (Ruijters
and Stoelinga, 2015).
One method that uses both bottom-up and top-
down is the Bow-Tie Analysis, which brings together
FTA and Event Tree Analysis in a flexible way. It
represents a multimedia approach, where the routes
from possible causes of a hazard to its potential con-
sequences are diagrammed out through preventive
and mitigative barriers. The technique identifies the
cause-and-effect relationship, hence indicating the in-
tervention points on which effective prevention or
mitigation of risk can take place. (Tait and Edwards,
2021).
2.3 Safety and Risk Assessment in
Human-Robot Collaboration
In their study, Lee and Yamada focus on the integra-
tion of FTA and FMEA for the design of safety func-
tions in robots that collaborate with humans (Lee and
Yamada, 2012). With their method, they determine
the safety integrity level required for the system, per-
form risk assessments to identify potential failures,
and show the design of safety functions that comply
with the determined safety integrity level. This ap-
proach is illustrated by the case study of the skill as-
sist system, an assistive device used in manufactur-
ing and social settings. The proposed methodology is
limited to the design of the safety function for system
failures and cannot be directly applied to other safety
functions that can prevent dangerous events caused by
human factors.
Zacharaki et al. give an overview of safety bound-
aries in human-robot interaction. They focus on the
aspects related to safe interactions between humans
and robots (Zacharaki et al., 2020). The overview
highlights various safety techniques, such as safety
zones, real-time monitoring or dynamic safety bound-
aries. These methods help to prevent accidents in col-
laborative workspaces and strengthen trust between
humans and collaborative robots. In their work, ex-
isting safety analysis techniques were examined and
compared but not actively applied.
In their paper, Huck et al. mention that the risk
Safety Assessment of Human-Robot Collaborations Using Failure Mode and Effects Analysis and Bow-Tie Analysis
433