These complex systems have a series of bays where products are stored and can be stacked up to 20 units high. The aisles between the bays have tracks down the centre. 

An automated car drives the track as it moves to the bin location. The drive is calibrated using an encoder or other measurement device so that the car goes to the correct bin location. 

Because of belt wear, wheel slippage, or chain expansion over time the retrieval unit may not end up at the exact location. It may be off by only a fraction of an inch, but this could be enough for the system to function improperly.



New vision sensors were designed to solve this type of problem. The solution was to drill a hole in the horizontal or vertical support member of the storage rack at each bin location.  A camera system is installed on the ASRS that detects the hole. When the retrieval system gets to the bin location, the camera sees the hole.

If it is off centre, four digital outputs, +X, -X, +Y, -Y are used to instruct the system which directions to travel to center the camera precisely over the hole. 

Once centered, the bin can be pulled without damage to the rack structure.  The ASRS system will also use this new position to recalibrate itself.  

Applications are not limited to high-bay warehouses. Low-temperature cameras have been designed for cold-storage applications.  

These cameras can also be used for unique applications including determining the roundness, diameter, or location of holes in an object.

Tim Cicerchi is product manager at Pepperl+Fuchs ( This e-mail address is being protected from spambots. You need JavaScript enabled to view it ).
www.pepperl-fuchs.us