Fraunhofer sensor system to monitor warehouse shelves

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Researchers at the Fraunhofer Institute for Microelectronic Circuits and Systems in Duisburg have devised a wireless, sensor-based system to provide continuous monitoring of the condition of storage shelves in warehouses.

Typically, to protect storage shelves from collisions from forklift trucks, their supports are fitted with an air cushion designed to absorb the impact. The Fraunhofer researchers took advantage of this fact by integrating sensors in the protective fitting that measure the pressure within the air cushion.

If an air cushion is hit, the sensor registers the change in interior pressure and transmits the data via a series of repeaters positioned at several points throughout the warehouse to a central control station located in the warehouse manager’s office.

Then, by checking the base station on a regular basis, the warehouse manager can determine when and where the last collisions took place. The system also automatically provides a report of whether the impact was harmless, of medium strength or serious. While no immediate measures are required for light collisions, in the event of a serious incident, the warehouse manager can send an employee to the shelf in question.

The Fraunhofer researchers have configured the system so that the electronics spend most of their time in energy-saving sleep mode. Only when a fluctuation in pressure occurs do the sensor nodes ’wake up’ and switch to active status. At certain intervals, however, each sensor node sends a ’sign of life’ signal, along with its current battery status, to a repeater. This ensures that the failure of a signal node will not go unnoticed and will be reported to the control station.

The researchers expect to demonstrate the system by the end of March and a field test is also planned for a warehouse facility.