Royal Navy automates its main store
Royal Navy automates its main store
Keywords AGV,Automation, Pick and place
As part of a multi million pound investment in "100 Store", the Central Storage and Distribution Facility(CSDF) at Her Majesty's Naval Base in Portsmouth, nine automated guided vehicles from Indumat have been installed to transport palletised goods around a one kilometre travel route between the highbay warehouse and the picking areas.
Following well-publicised reviews in the mid-1990s of all the armed forces, the site was upgraded to supply the majority of general, electronic and marine stores needed to keep the Royal Navy's surface fleet operating. Housing a large proportion of the inventory is 100 Store, a vast listed building covering 4.4 acres.
By August this year it will be linked by monorail to the nearby Portsmouth distribution centre, along with the adjacent general-purpose store. This combined operation, known as the"one roof concept", will house 80 per cent of CSDF's task.
When the project sponsor at the base was researching how to achieve the pallet movement rate required of 100 Store, comparisons were made of systems based on AGVs and on conventional fork lift trucks. The former were considered to be safer, as the pallets need to be transported around a relatively confined area, where crane drivers need to move on foot and where manually-driven picking trucks cross a central spine to service both sides of the warehouse.
Taking labour costs into account, it was calculated that AGVs would also provide the more economic solution. In addition, it was felt that AGVs could support "non-standard" hours operation better than manned lift trucks.
The main contractor,Cleco, therefore recommended AGVs, destined to become the first to enter service in any Royal Navy site. One factor in Indumat's favour was the operation by the army of a similar system at MOD, Donington, which has been running successfully since 1986.
The system went "live" at Portsmouth on 13 October 1997, with the maximum potential of transporting up to 75 pallets per hour from the warehouse to two conveyors feeding the picking areas and subsequently returning them to store. A total of 18,000 pallet positions are serviced, each accommodating one of three sizes of NATO pallet weighing up to one tonne (Plate 7).
Plate 7 Nine Indumat AGVs operate in 100 Store at Her Majesty's Naval Base, in Portsmouth. The two conveyors feeding the picking operation are pictured right
There are five main bays extending both sides of the central spine. Bay 1 is wide aisle and bays 2 and 5 are narrow aisle, all serviced by manual picking trucks, while bay 3 is equipped with Cleco order picking cranes.
These four bays are linked into the AGV network by P and D (pick-up and deposit) stations at either side of the aisle ends. A further bay is currently being converted into a mini-load storage system.
The P and D stations are three-tier, to accommodate pallets of different heights. First and second levels accept laden pallets up to 1,000 mm high, the former being used to deposit loads and the latter to pick up. The top level has unrestricted headroom and is used to deposit and pick up tall loads which can be up to 2,250mm high. All levels are accessed directly by the nine AGVs, each of which is equipped with a mast on which the fork carriage is raised to the required height.
The depth of the racking dictates that pallets are stored with the longer side facing out, so after retrieval they are orientated in the P and D stations such that they are presented end-on to the AGV forks. This in turn means that on arrival at either of the roller conveyors feeding the picking operation, a turntable has to rotate the pallet through 90°, before it continues its journey. Returned pallets undergo the reverse process.
Guidance of the AGVs around the network is by straight inductive wires, laid in the floor, with the vehicles free-ranging around curves. Two-way inductive communication with Indumat's Windows-based controller allows the system to be aware of the position and load status of every vehicle.
Written into the software is a program to clear AGVs from the intersection of the spine and bays 1, 2 or 5 when the corresponding picking truck has been instructed to cross to the other side of the warehouse. Vehicles are allowed to re-enter the area after the truck operator reads a barcode on the other side.
Inter-vehicle blocking throughout the travel route to prevent collisions is standard for installations such as this.
Sitting at the top of the computer hierarchy is the MOD ordering system, WITS, which downloads instructions to the warehouse management system. This in turn communicates with the Indumat controller, providing it with an ongoing sequence of jobs which are prioritised into a transport order list. The warehouse computer similarly communicates with the aisle trucks and the conveyor stations to control the whole operation.
Each AGV is equipped with numerous safety features, including side and rear safety contact strips. To detect obstacles in the path of AGVs when travelling in reverse, infrared sensors are mounted in the fork ends. This creates a potential problem when a truck approaches an aisle P and D station, as the galvanised steel baffles fixed to the ends of the racking would normally be seen as obstacles. To overcome this difficulty, the areas have been painted black so that they are invisible to the sensors, avoiding automatic AGV cut-out as the forks approach to lift or lower a pallet.
Two batteries have been supplied for each vehicle. One powers the vehicle while the other is on a mobile charging stand which doubles as a trolley to assist battery replacement when the operational one is depleted beyond a predetermined level.
For further information contact: Indumat Systems Ltd, Kingsclere Road, Basingstoke, Hampshire RG21 6XQ. Tel: +44 (0) 01256 470079; Fax: +44 (0) 01256 470072.
