Those looking for an automated storage and order picking system have a challenging job ahead. A visit to the LogiMAT trade fair in Stuttgart makes it clear that the number of different tastes is huge. LogiNews gives an insight into the evolution of 'automated storage and retrieval systems' (AS/RS).
The first automated storage and retrieval systems (AS/RS) were installed in the 1960s. They consisted of cranes on rails that could load and unload pallets fully automatically. Not long after, variants for storing smaller load carriers such as totes and trays emerged: the miniload cranes.
Miniload cranes are still in use, but have a major drawback. Since only one crane can be active in each aisle, inbound and outbound capacity is limited. As a solution, the first multi-shuttle systems were developed in Germany after the turn of the century: storage systems with several shuttles on top of each other - one on each level - increasing capacity by a multiple.
Cube-shaped storage
From 11 to 13 March, LogiMAT showed that the continued evolution of AS/RS systems follows two tracks. The first track consists of cubic storage systems with a grid in which high stacks of storage bins are placed. The best-known example is the AutoStore system. The entry and exit of bins in the AutoStore system is not handled by cranes or shuttles, but by robots that drive across the grid, 'dig up' the right bins and bring them to a workstation.
AutoStore has two main drawbacks: the maximum height is limited to six to seven metres and the time for digging up the bottom bin is quite long, as the robots must first put away all the bins above it. The LogiMAT showed other cube systems such as Instapick, Gridstore, Bluesword and Volume Dive that demonstrated solutions to this. Consider creating aisles in the storage system so that the robots can lower a tool to pick up the bottom bins from the side.
Ride and climb
The other track is through the development of autonomous mobile robots. A pioneer in this field is Exotec, which won the LogiMAT innovation prize six years ago with its robots that can not only drive on the floor, but also climb into racks. These robots bring the storage bins from the storage system to the workstations, eliminating the need for roller conveyors. In Stuttgart, this concept was followed by Knapp and Hai Robotics, among others, which also launched mobile robots with climbing capabilities.
In addition, Hai Robotics, like a host of other Asian warehouse fitters, has developed an AS/RS system in which different types of robots work together. The first type consists of robots with tall masts that do nothing but retrieve stock bins from ten to 12-metre-high racks and place them at the bottom location. There, the stock bins are picked up by smaller and more agile robots that take the bins to a workstation.
Back to square one?
These solutions also have a major drawback: tall robots in particular are relatively slow. One reason is the pivoting of the mast, which sometimes takes a long time for the robot to be correctly positioned and pick up a bin at a height of ten metres. Again, something has been found to address this, as Libao and Mushiny, among others, showed: a machine mounted to the rack that has a load lifting device that slides from one storage location to another at high speed. This solution looks suspiciously like the first miniload cranes from the last century, which seems to have come almost full circle.
Does this mean we are back to square one? Certainly not. The new generation of AS/RS systems is distinguished from miniload and shuttle systems by its flexibility and scalability. Anyone wanting to increase the inbound and outbound capacity of a miniload or shuttle system needs to expand the system with additional racking and extra aisles. Those who want to increase the capacity of the new systems only need to deploy additional robots. This allows companies to start with a small system and let it grow with the business. This is nice in these uncertain and unpredictable times.
