Risk Assessment - Universal Robots UR5 with CB2 User Manual

4.3 Risk assessment

One of the most important things that an integrator needs to do is to make a
risk assessment. Universal Robots has identified the potential significant hazards
listed below as hazards which must be considered by the integrator. Note that
other significant hazards might be present in a specific robot installation.
1. Entrapment of fingers between robot foot and base (joint 0).
2. Entrapment of fingers between the arm and wrist (joint 4).
3. Penetration of skin by sharp edges and sharp points on tool or tool con-
nector.
4. Penetration of skin by sharp edges and sharp points on obstacles near the
robot track.
5. Bruising due to stroke from the robot.
6. Sprain or bone fracture due to strokes between a heavy payload and a
hard surface.
7. Consequences due to loose bolts that holds the robot arm or tool.
8. Items falling out of tool. E.g. due to a poor grip or power interruption.
9. Electrical shock or fire due to malfunction of power supplies if the mains
connection is not protected by a main fuse, a residual current device and
a proper connection to earth. See section 1.4.7.
10. Mistakes due to different emergency stop buttons for different machines.
Use common emergency stop function as descriped in section 2.3.1.
However, the UR5 is a very safe robot due to the following reasons:
1. Control system conforms to ISO 13849-1 performance level d.
2. The control system of the robot is redundant so that all dangerous failures
forces the robot to enter a safe condition.
3. High level software generates a protective stop if the robot hits something.
This stop force limit is lower than 150N .
4. Furthermore, low level software limits the torque generated by the joints,
permitting only a small deviation from the expected torque.
5. The software prevents program execution when the robot is mounted dif-
ferently than specified in the setup.
6. The weight of the robot is less than 18kg.
7. The robot shape is smooth, to reduces pressure (N/m ) per force (N ).
8. It is possible to move the joints of an unpowered robot. See section 4.4
The fact that the robot is very safe opens the possibility of either saving the
safety guards or using safety guards with a low performance level. As a help in
convincing customers and local authorities the UR5 robot has been certified by
the Danish Technological Institute which is a Notified Body under the machin-
ery directive in Denmark. The certification concludes that the robot complies
All Rights Reserved
88
4.3. Risk assessment
UR5