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Field Layout Insights     Feb 15, 16

Active Vs. Passive Tracking For Laser Prisms

What is Active and Passive Tracking

Have you ever been on a job site, laying out a wall or a building slab and suddenly your Trimble Robotic Total Station starts acting like it is possessed?  Or you are diligently working, plotting your points from your hand held and a co-worker, dressed in his PPE, walks in front of the robot and it then starts following the reflection of his safety vest? The robot seems to be following random signals coming from unknown sources and it makes layout frustrating and complicated.

The issue is industry wide.  Passive tracking relies on reflection off the glass in the prism and there-in lies the crux of the matter.  The robot cannot determine if the reflection is from the prism, a safety vest or the mirror of a construction vehicle parked on site.  It is up to the operator to ensure all but the prism reflection is minimized.

Active tracking utilizes LED lights to create a signal that the robot recognizes.  The LED can be adjusted to 9 different settings on the Trimble MT1000 Multitrack prism.  Once robot and prism are set to the same channel, other reflections are ignored.  This is most helpful on congested job sites, sites with many reflective surfaces, or with many lasers.   Read more about Mr. Sabbah’s thoughts on active versus passive tracking.

– Scott Mayer, BuildingPoint Southeast
Building Construction Specialist