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It is permissable to guard a robot using only a laser scanner to detect operator approach and stop movement or is a barrier (such as a fence) required?
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The safety laser scanner is sufficient. Perimeter safeguarding would then be provided the the scanner making a guard not required.
Clinton, For many robots, a safety scanner alone is not sufficient since they have lower safety category levels than say a light screen. This is because a scanner is "a re-programmable safety device". To do this, you must have the correct safety check software (KUKA = Safe operation, Fanuc = DCS, etc) running on the robot controller. This software helps the system perform at a higher safety category level than what you can achieve with a scanner alone. You can set up multiple zone outputs in most scanners. In general, you would use the outer zone output to slow the robot a bit and notify the operator that they are in the zone, the second zone would be 10% once the operator is still out of reach but getting closer. The third will stop the robot in its path. The distance for these zones depends on the worst case deceleration curve for that robot model with EOAT and parts attached. Lastly, you really need to do an air tight risk assessment to uncover any other hidden risks. Thanks!
A barrier is only required to contain a hazard. As long as requirements are met for stopping times and safe distances as scanner or safe vision system or other volumetric detection device (lidar) can be used. Pilz has provide its SafetyEYE product for several years in this type of application.