At the end of a long day on the job, the forklift driver wants to deposit the last palettes quickly before heading home. With a little too much momentum he steers his forklift toward the shelf and collides with a shelf support. This is every-day situation in large facilities where employees often have to maneuver goods through the narrow aisles, often under time pressure.
Even harmless-seeming collisions are not really safe though, because over time they may in fact destabilize the shelf supports. In the worst case, the high-rack storage can come crashing down – a serious hazard for the employees below. This is why officials must routinely check the supports for any damage.
Up until now, an employee has to inspect each shelf individually. In addition, there is one further drawback: If a support suffers damage immediately after an inspection, it goes undetected until the next round. A new monitoring system developed by researchers at the Fraunhofer Institute for Microelectronic Circuits and Systems IMS in Duisburg, Germany in collaboration with IWS Handling GmbH can solves those issues.
With a network of wireless sensors, officials can monitor the condition of each individual support around the clock.
“Since DIN EN 15635 was introduced, the demands on the operation of shelf systems have increased significantly,” said Dr. Weiner, managing director at IWS Handling. “Regular inspections have become indispensable as a result.”
Typically, to protect them from collisions, they fit the supports with a kind of air cushion designed to absorb the impact.
“We have integrated sensors in this protective fitting that measure the pressure within the air cushion,” said Frederic Meyer, project manager at IMS. If someone hits an air cushion, the sensor registers the change in interior pressure and reports this via radio relay to a central control station in the manager’s office. Repeaters positioned at several points throughout the facility receive the messages from the sensor nodes and smoothly pass these along to the control station. All the manager needs to do is glance at the base station to know when and where the last collisions took place within the hall. The system automatically provides a report of whether the impact was harmless, of medium strength or serious. In the event of a category three incident the warehouse manager immediately will send an employee to the shelf in question.
Energy management played a central role in developing this new technology.
“After all, the use of such a system only pays off if you aren’t constantly having to replace the batteries in the sensors,” Meyer adds. The researchers in Duisburg have configured the system so 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, though each sensor node sends a “sign of life” along with its current battery status to a repeater.