Driverless innovation

E&K Automation, has converted three Linde K-Range VNA stacker trucks for the Samsonite warehouse in Oudenaarde, Belgium.Working alongside operator controlled lift trucks, the computer controlled AGVs move along the narrow aisles following inductive guide wires set into the floor.

Linde trucks are fitted with an E&K laser-based navigation system so they can free-range off the wires into other areas of the warehouse. In this case, the trucks guide themselves by triangulation using reflectors mounted on the warehouse walls.

Data communication between AGVs and the E&K controller is via a wireless LAN.

The trucks are also equipped with telescopic forks and pallet profile control, which checks that the dimensions of the pallets coming from production are correct and therefore that they can be stored in the automated warehouse.

Samsonite products are split into fast and slow moving products. Every item can be a slow or a fast mover according to season and promotional campaigns, increasing logistical complexity. So in 2007, Samsonite decided that a new, dynamic bulk storage and order picking area was required for slow movers, primarily to release capacity for handling fast moving items.

Initially, three alternatives for the dynamic storage area were considered: first, a solution with fully automatic cranes; second, manually operated VNA trucks; and third, manually operated reach trucks. All three ideas were rejected due to the large number of trucks required and the high cost.

The search for further alternatives led logistics manager Germain Ghys to E&K Automation.

The automated high bay VNA stacker trucks provide back-up in the event of electronic failure, as they are equipped with an operator seat and can be manually driven in an emergency. All of the other standard functions of the Linde lift trucks also remain.

Simple maintenance was a further reason for choosing this solution. Furthermore, the availability on the Linde K truck of an interface that E&K Automation could readily use to access the electronics of the high bay VNA stackers allowed the trucks to be automated.

Construction began in the summer of 2008 on a greenfield site and was completed in April 2009. Samsonite did not need the support of a general contractor, because the company was able to use its own automation expertise.

"Without our own experience, it would not have been possible to carry out a project like this so quickly," says Ghys. "All subcontractors, from the rack builder to the suppliers of conveyer systems, electrical networks and security systems as well as the automatic high bay stacker trucks were selected by us, while our in-house skills allowed us to develop our own electronic solutions." The new storage area comprises racking on five levels along 12 aisles up to 160 metres long. In total there are 11,520 storage locations and 1,100 picking locations for a maximum of one million individual items.

The pallet racking is divided into six separate sections. Each consists of an order picking aisle and two narrow aisles for replenishment, which are serviced by the three AGVs. Every afternoon, orders received by 12.00 noon are processed. The WMS determines which products are already available at a pick location and which goods still need to be replenished. On average, the trucks rearrange around 20 per cent of the stored goods until every product can be found at an order picking storage location.

Samsonite employees use a route-optimised pick list to take the items from the order picking locations, attach a barcode label and place them on a conveyer belt in the middle of the pick aisle.

From there, they are transported to a consolidation area where they are grouped by destination. A manual electric fork lift truck loads the pallets into a lorry using a dock leveller. Around 27 lorries with an average of 1,000 to 1,500 items each make their way daily to retailers throughout Europe.

Slow moving products are transported from production to the warehouse on Linde electric counterbalance trucks. Each truck places the laden 1,400 x 1,400 x 2,000mm high special pallets into the marshalling area. After pallet profiling is completed, the load is transferred to the automated storage area of the warehouse via cantilever pick and drop stations.

AGV movement instructions are sent from the E&K system controller based on order information from the WMS. The trucks automatically pick up the pallets on their telescopic forks and transport them to the required rack location.When transferring pallets, the AGVs use an optical system to ensure positional accuracy. There is a 150mm safety clearance between the trucks and the load in the racks.

Since there is only 75 to 100mm of space between pallet storage locations, a pallet profiler mounted on the AGV forks confirms that the load can be stored in the rack and ensures that products housed in two adjacent rack positions do not touch each other. If the dimensions of a load exceed the standard pallet profile, the automated Linde narrow aisle truck is switched to manual operation.

When the AGVs have no outstanding orders, they travel to a designated station for automatic charging. The 80V/775Ah leadacid battery is charged through contact pads in the floor.