Collaborative Robot Safety
PreciseFlex™ DDR Collaborative Robots
P/N: PFD0-DI-00010, Rev 5.0.0, April 9, 2022
30
Copyright © 2022, Brooks Automation, Inc.
Robot Workcell Design
Introduction. The PFDD robots are always configured as a “Collaborative Robot”.
They are
designed for applications with a payload of 6-8kg depending on the model. High speed impacts for the
robots, which could trap an operator against a surface may be avoided by teaching an “Approach”
position which is a greater distance from a fixture than any operator appendage that might enter the
workcell, and first moving to this “Approach” position at high speed, then moving to the final position at a
slow speed, for example 150mm/sec or Speed 25%, which will not create excessive force in the event of
a trapped operator.
The Collision Force Table on the previous page indicates under what speed, payload, and
collision conditions the collision force may exceed the recommended ISO force limits. From the
table it can be seen that collisions in free space, even with a 5.4kg payload at 100% speed should
not injure an operator as long as a safe end effector is attached to the robot. However, when the
robot approaches within 100mm of a rigid surface, an approach point should be taught, and the
robot should be slowed down to a speed indicated by the table to avoid trapping an operator
against a rigid surface at high speed.
Workcell Design Recommendations for the PFDD robots
Workcell designers are referred to EN ISO 10218-2:2011 for information on designing safe workcells.
Note especially that even a safe robot, when equipped with a tool that renders it dangerous, should be
protected from contact with an operator. For example, a robot which can only apply 60 Newtons of force
could plunge a needle through a person’s hand.
Note that designing a robot workcell can be compared to driving a car. When approaching obstacles (or
parking) you slow down.
Safety Glasses.
It is required that operators who will move inside the work volume of any robot wear
safety glasses at all times, both to prevent any poking injury to the eyes, and also because the machine is
often moving around liquids which may be hazardous to the eyes.
Workcell Layout
. The PFDD robots are designed so that the outer link or inner link of the robot cannot
move down and touch the mounting surface, thus trapping an operator’s appendage. The workcell
designer will be programming the robot to move workpieces from one location to a second location and
back again. When moving in free space the robot may make motions at higher speeds. When
approaching rigid surfaces, the operator should slow down the robot as indicated in the collision tables to
avoid any possibility of injury.
See Appendix A below for an example PLr evaluation for an example PF400 workcell.
