Shuttle system gets smart to meet e-commerce demands
Control system case study: Using EtherCAT and PC control, Swisslog’s shuttle system delivers a data-driven distribution center solution that cuts hardware costs 25% in warehouses.
- Swisslog’s shuttle system cuts hardware costs 25% in warehouses using EtherCAT and PC-based control systems.
- Consolidating machine control and communication on a single embedded PC and using compact EtherCAT I/O helped the company realize significant savings.
With growing e-commerce demands and tight labor market pressures, today’s smart warehouses and distribution centers require increasingly data-driven technologies, including for automated motion control. For intralogistics specialist Swisslog, addressing this challenge requires machines with greater intelligence, such as the company’s CycloneCarrier shuttle system.
“E-commerce is the fastest growing segment of the U.S. economy,” said Tom Rentschler, head of marketing for Swisslog Warehouse and Distribution Solutions – Americas. “Intralogistics operations need much more flexible, scalable, adaptable and user-friendly solutions. These technologies can augment, rather than replace, human beings, helping workers increase throughput in the distribution center while no longer requiring them to walk 15 miles each day to pick items.”
Swisslog uses many logistics solutions including warehouse management system (WMS) software, robot-based item picking, case palletizing, mobile robots that move shelves to picking stations and many others. Swisslog also provides traditional warehousing systems, such as palletizers, pallet cranes and pallet conveying technologies.
Intralogistics motion controls applications, PC-based control
The compact shuttle vehicles for cartons and totes travel at speeds up to 4 m/s across the shelving, which can reach up to 150 m long and 25 m high. The vehicles’ load-handling arms extend to either side and can adjust the space between arms to safely handle items of varying widths. The shuttles unload items onto transfer conveyors that serve as buffers to dynamic single- or double-deck vertical lifts. Depending on the shelving size and number of shuttles, the system can achieve a throughput of tens of thousands of items per hour. Each shuttle must frequently communicate with the WMS to log item locations in the constantly rotating inventory. “It must react quickly if, for example, an order changes or there is a change in the SKU sequencing requirements,” Douglas said.
Swisslog recognized the need for a controls platform that could handle increased quantities of data and communicate horizontally and vertically, even up to the cloud, if needed. This realization coincided with the development of their WMS and the need for greater connectivity across the company’s systems. As a result, Swisslog began to transition its portfolio to PC-based control technology, standardizing on hardware and software solutions from a new automation vendor.
“We made this strategic decision because the vendor had, at the time, the most complete and cost-effective portfolio available,” Douglas said. “Swisslog’s intention is that it will transition every product offering to include PC-based control in the near future, including the more traditional pallet cranes and conveyors. So far, we have installed more than 1,000 machines worldwide that are equipped with the new controls.”
Automation, shuttle system, machine controller
Among the automation technologies, the shuttle system relies on embedded PCs for controller hardware. The specific DIN rail-mounted machine controller measures only 124 x 100 x 92 mm. With just a single-core processor, the mid-range controller handles all machine logic and data acquisition processes with fast cycle times, according to Douglas.
“The controller provides us with the processing power needed to reliably handle all machine functions. Form factor was also a concern, but the compact embedded PC fits inside the shuttles without issue,” he said. “The controller hardware offers the universality and extendibility that we need to continue developing the shuttle system.”
As the universal runtime and engineering environment for machine programming, flexible automation software provides similar benefits, in part through the extreme portability of code to new projects. While the automation software’s integration into Microsoft Visual Studio enables programming in computer science languages, it is also ideal for all IEC 61131-3 programming languages, including object-oriented extensions.
Motion control programming languages, industrial Ethernet
Swisslog engineers appreciated this capability because, prior to standardizing on the new automation vendor, they wrote most of their code using IEC 61131-3 languages such as structured text (ST) and function block diagram (FBD).
Douglas said, “Because the function blocks were so foundational, we didn’t want to lose development work when moving to other projects, and the new vendor made code reuse possible and uncomplicated.”
For networking, the shuttle system uses the EtherCAT industrial Ethernet system, which provides flexibility in topologies and supports up to 65,535 devices on a single network. EtherCAT helps with cross-vendor communication, allowing Swisslog to connect to third-party Profinet or EtherNet/IP devices as needed. However, the company strongly prefers to select devices such as barcode scanners that specifically support EtherCAT. For hardware, the shuttle system uses compact yet expandable I/O modules, which connect directly to the controller via a shared backplane and can be widely distributed across applications via EtherCAT Couplers and junction terminals.
Programmable safety terminals are integrated in the same segment as non-safety I/O in the shuttles. The “black channel” approach of [functional] Safety over EtherCAT (FSoE) provides TÜV-certified communication over the EtherCAT network.
“Using integrated safety components allows us to reliably and safely control each CycloneCarrier according to the latest safety standards without the need to stop the entire system. Because of these benefits, we use programmable safety on every project,” Douglas said. “Of course, safety is a requirement for every application by default, but having it integrated to this extent really answers our overall design requirements.”
Control cycle times, motion control costs, e-commerce
By leveraging automation technologies from a new vendor, Swisslog created a flexible, scalable and adaptable shuttle system for distribution centers. A recent project for a major U.S. retailer, for example, involved 65 shuttles working round-the-clock to process 650,000 SKUs per day. Implementing the shuttle system boosted throughput for the company while saving workers significant physical exertion.
“The adoption of goods-to-person technology with reliable automation technology is really important to our customers, since they can no longer scale up their labor force seasonally, for example,” Rentschler said.
By consolidating machine control and communication on a single embedded PC and using compact EtherCAT I/O, Swisslog also experienced significant savings. “Overall hardware costs are roughly 25% lower by using the new vendor’s solutions compared to what would be required to accomplish the same tasks with another vendor’s components,” Douglas said.
The shuttle system achieved these capabilities through high-speed EtherCAT communication and the processing power of PC-based control. With the embedded PCs and automation software, the Swisslog machines achieve cycle times in microseconds, rather than the milliseconds they needed with previous solutions. The smart machines also can acquire critical data beyond performance data, such as temperature irregularities in facilities that handle perishable products, and display this information via dashboards built into the company’s WMS.
While traditional palletizing equipment usually remains in the same location, unchanged for a decade or more, new e-commerce solutions need to offer greater flexibility to meet changing consumer or corporate requirements. The modular controls platform Swisslog implemented enables customization to shelf and shuttle setups, whether to modify slightly or disassemble and rebuild the system in a different configuration, in an different warehouse.
“Through our standard platform based on PC-based control, we could use a CycloneCarrier shuttle in a small system targeted to a specific application and then use the same machine in a much bigger facility doing a completely different job,” Douglas said. “To accomplish these feats, all of that flexibility must be built into the automation system from the beginning.”
Keywords: industrial PC, advanced process control, EtherCAT
Swisslog’s shuttle system cuts hardware costs 25% in warehouses using EtherCAT and PC-based control systems.
Consolidating machine control and communication on a single embedded PC and using compact EtherCAT I/O helped the company realize significant savings.
Read more stories from the author at www.controleng.com.
How is your company handling logistics and operations and what are they doing to make it better?
For more information: