Robots have become such an integral part of the German economy since the dawn of Industry 4.0 that it is no longer possible to imagine it without them. To date, however, the mechanical assistants have mainly been used in the area of production, while their presence has remained somewhat unremarkable in the field of logistics. If they are used at all, then it currently tends to be for transporting goods around large warehouses in the form of automated guided vehicles (AGVs). Most companies are yet to address the subject of using robots for order picking.
In view of rapid technological developments and the advantages of automatic systems in terms of efficiency, speed, and security, a rethink is now taking place in the industry and a growing number of logistics companies can envisage using robotic systems in the actual area of storage and retrieval in future.
This is necessary, too, because given growing inventories and an already highly noticeable skills shortage caused by demographic change, the logistics industry faces big challenges. Automated systems and autonomous order picking make perfect sense as a way of solving these issues. While the concept of transporting goods around a warehouse with the aid of conveyor belts or the aforementioned AGVs is relatively straightforward to achieve, it is far more difficult to automate the process of order picking, which involves putting together different items to make a consignment. According to statistics, more than 90 percent of this kind of work is still done manually. This is due to the fact that it has thus far proved simply too complicated to satisfactorily and inexpensively replicate the human eye and human hand (with its sense of touch) in a robotic solution.
The particular difficulty lies in the fact that robots not only have to navigate their way safely around an autonomous warehouse, but also cope with the permanently changing conditions. They have to find ways of avoiding other systems and must also be capable of picking the exact quantity of differently sized items from the shelf or at the picking station. Since they are unlikely to completely replace human workers anytime soon, they also have to interact in a kind of human–robot cooperation without disturbing or endangering the employee.
Precise picking and identification – the two big problems for robots
Developers have now mastered the complex software-based control concept that forms the basis for the coordinated movements of the robotic gripping arm. However, the process of actually gripping the goods poses a much bigger problem, which is primarily due to the highly heterogeneous nature of the product range. The goods picked in a warehouse sometimes differ significantly in terms of their shape, rigidity, stability, weight, volume, and surface structure. Different techniques are used to handle these items successfully. Yet regardless of whethe
r clamping, traction, or vacuum grippers are used, no single method is capable of covering the entire range of items. This means that even more variable solutions are needed to retrieve all goods really reliably.
Another reason for the difficulty in automating picking processes with robots is the lack of flexibility when it comes to image processing by automatic systems. Previously it was simply too difficult for the machines to clearly identify the sheer number of different goods. Companies therefore managed by painstakingly programming each item’s characteristics (size, weight, special handling instructions, etc.) and its appearance into the software. This solution perhaps makes sense with a reasonable amount of items, but if a company stocks several hundred or even thousands of items, it soon reaches its limits. However, a combination of 2D and 3D image processing is now helping to reduce the robots’ confusion, allowing them to identify a wide range of products and packaging, even if they are stacked on top of one another or standing at an angle.
Jewelry manufacturer Maty is demonstrating how this can be done. It has already successfully automated the retrieval of its goods. At the heart of the system is a software-controlled pick-and-place robot that fully automatically retrieves the items of jewelry and their accompanying cases for further picking. The robots and employees are supported by automated storage units with integrated pick-by-vision equipment supplied by the intralogistics manufacturer Kardex Remstar. These help to significantly increase the speed and precision of the picking operation. Compared to processing the orders manually, this approach has led to a 50 percent increase in the output of packages ready for shipping. The picked goods are temporarily stored in ten horizontal carousel storage units from Kardex Remstar, where they are held in a total of 44,000 spaces until they are ready for shipping.
How are the goods picked?
A distinction can basically be made between two approaches to robot-based order picking:
This system is used worldwide by Amazon, among others, in its warehouses (with the aid of its own Kiva robots). The concept involves robots picki
ng up small shelf units and taking them to the picking table, where the warehouse employees retrieve the required items and place them in the shipping boxes. According to Amazon, around 45,000 Kiva robots were in use in 20 of its distribution centers in 2016, a rise of 50 percent on 2015.
With this approach, the goods are transported to the picking robot (via floor conveyor systems or from automated storage lifts, for example). The robots then retrieve the required items and prepare them for shipping. This solution already works fully automatically, but – unlike the approach favored by Amazon – it has the drawback of requiring the installation of a complex material flow system in the warehouse. Systems like the above-mentioned Maty solution go one step further in that the goods are automatically retrieved from vertical or horizontal storage units and then autonomously picked by the robot. At this year’s LogiMAT, Kardex Remstar is presenting its LR 35 Vertical Buffer Module, which is optimized for the fast picking of small parts, in conjunction with a robot solution, which can independently store and retrieve items from the unit. The advantages of such a solution are clear:
- Fast and precise order picking
- Ready for use around the clock
- Automatic storage and retrieval
- Flexible adjustment to new items
- Products identified using innovative camera software
- Robots can retrieve items weighing up to 8 kg
And the robots are not restricted to picking orders, because they are just as suitable for processing returns, which is becoming ever more important in the mail-order business.