CAUTIOUS
COLLABORATION
While cobots o er signifi cant advantages to manufacturers
looking to embrace Industry 4.0, they also bring signifi cant
safety risks that must be acknowledged
Collaborative robots (cobots) play a key
role in the adoption of Industry 4.0.
They can be used in a wide range of
industrial applications. Because they
have various integral safety features,
they can work with or near people and
can also adapt easily to changing needs. This
means that the productivity of many repetitive
tasks can be signifi cantly increased, enabling
manufacturers to reap the benefi ts of a high return
on their investment.
The safety features of cobots include
lightweight body, collision detection technology
and minimised pinch points. However, further
safety measures might still be needed for specifi c
applications - including the end eff ector, the
product and other equipment in the collaborative
workspace (a safe space where robots and people
can work together). For a cobot application to
be truly successful, it must incorporate safety
considerations based on comprehensive risk
assessments.
So, what are the industry safety standards
and solutions that will enable a company to
gain the maximum value from cobots within a
collaborative workspace?
Safety standards
robots and incorporate force and speed
monitoring capabilities. When fi tted with
Cobots are more compact than conventional
safety devices that detect anyone entering the
collaborative workspace, they can often work
at higher speeds when people aren’t present,
which helps to maximise throughput.
Two key safety standards that defi ne the safety
functions and performance of a cobot are ISO
10218-1, ISO 10218-2 and ISO TS15066. The latter
sets the force and speed monitoring of the cobot
based on application data, human contact area
and workspace hazards. There are two types of
human contact: transient (non-clamping
contact) and quasi-static (involving situations
that can cause a body part to be clamped).
Manufacturers who aren’t familiar with the
requirements of ISO TS15066 can hire a safety
assessment provider to make
the calculations, take the
measurements and recommend
improvements to the safety of
the collaborative application.
ISO 10218 and ISO TS15066
also provide guidance on
cobot teaching. Many cobots
use intuitive ‘hand guiding’
mechanisms for teaching
new tasks. This avoids the
need to program the specifi c
movements of the robotic
arm. The hand guiding mode
monitors force and speed
so that the teaching process
complies with safety standards.
Safe teaching & operation
Prior to teaching, the robot
must be stopped before the
operator enters its workspace.
Alternatively, a safety device
(e.g. an area scanner) must carry
out a protective stop as soon as
the operator is detected.
HEALTH & SAFETY OCTOBER 2020
Prior to operation, the
operator must vacate the
safeguarded space. This can be
verifi ed by safety sensors or
additional operator verifi cation.
Intentional mode selection is
needed to re-enable the robot
for operation.
Safety in the
collaborative workspace
Cobots operate near other
equipment that could be
dangerous. It is therefore
important to list and map out
all additional equipment in the
collaborative workspace (which
must be clearly marked). Each
device must be assessed for
potential hazards and for safety
sensors that could prevent
human and equipment damage.
Non-collaborative safetyrated
equipment that might
need safety devices includes
material handling, tooling,
grippers and actuators and
machines. Safety devices can
usually be integrated easily into
a cobot application.
Several solutions can be used
to safeguard the collaborative
workspace. In open areas and
applications with low hazards,
these include safety area
scanners and mats. In gated
or limited areas with more
hazardous applications or highspeed
operations, safety light
curtains and safety switches can
be used. In areas with active
hazards or operations that
could cause a hazard, operators
can enable a ‘deadman’ switch,
which automatically turns off if
the user stops exerting pressure.
BY PETER LANGE, BUSINESS DEVELOPMENT MANAGER, OMRON EUROPE
The operator can use a
simple trigger, button or mode
selection to activate teaching
if safety force and speed
monitoring are in operation.
If not, a three-position safety
enable is required. According
to the safety standards, the
teaching mode transition
must be deliberate, mustn’t
lead to any unexpected motion
and mustn’t create additional
hazards. The operator must
be aware of any surrounding
equipment and possible risks
to safety at all times. To
enhance operator safety, it’s
possible to enforce limits on
motion: for example, space and
soft axis limits.
32 www.manufacturingmanagement.co.uk
/www.manufacturingmanagement.co.uk
