The distribution center in question spans multiple warehouses spread over a pretty large area. A large yard surrounded by a tall chain link fence envelopes the buildings, providing ample parking for trailers and other vehicles.
During most of the day, a steady stream of trucks delivers inbound goods, including lots loaded on local delivery vehicles, others destined to be split and stocked, while other goods continue their journey to faraway destinations.
The place is abuzz with crews operating lift trucks and pallet trucks. Inspecting, unloading, picking, sorting, putting together the cargo to be loaded onto outbound trucks. In one of the warehouses, automated guided vehicles pick, carry and deliver to the packing center.
A Warehouse Management System (WMS) orchestrates the center’s operation, predicting the schedule, anticipating the hourly pulse of the place and the resources needed. A Warehouse Control System (WCS) manages the minute-by-minute decisions, directing the automated equipment, reallocating staff and resources to deal with last-minute changes in requirements, resources and schedules, delays, unanticipated requests, equipment outages, congestion.
Location awareness enables warehouse control and transportation management systems to know the physical location of employees and mobile assets in real time. Combining the known location of each of the myriad moving parts in this complex system with identification technologies, such as RFID, barcodes and QR codes, makes it possible to devise cost-effective solutions to increase operational efficiency.
Staff and asset tracking
Employee location tracking throughout the day, enables the WCS to learn how human resources are allocated. What personnel shortages, if any, take place through the day? What events trigger them? Are there long stretches of idle time? Who can be reallocated to take care of a schedule change? Who is available where, to deal with a new load arrival?
The maintenance subsystem keeps track of the lift trucks’ whereabouts throughout the facility, aware that each of them is either operated by certified personnel or is idle, knowing how long it has been in operation since the last maintenance, when maintenance is due, and who last serviced it.
Insights into personnel and asset utilization can shed new light into the right staffing levels throughout the day/week/month and the resources (e.g. lift trucks) needed to support the required activity levels.
Handling schedule changes
Tracking the location of inbound trucks way before they reach the distribution center (DC) enables managing the schedule of employees and resources to handle the load as efficiently as possible. A truck that is delayed in traffic, bringing cargo to be unloaded and forwarded to other destinations, may trigger changes in the schedule. Should outbound trucks wait for the delayed cargo to arrive? Or should they leave to prevent further delays? The answer may be informed by knowing the location and speed of the inbound truck.
When inbound trucks must be rapidly unloaded and their contents transferred to those whose departure has been delayed, available crews and resources may have to be reassigned and mobilized to handle the schedule change. Knowing who and what is available and where everyone and everything is located may be critical for ensuring the best possible efficiency.
Automated identity and data collection enables pickers and placers to ID every product and lot as it is stored in multi-level racks in warehouses. As goods are placed on these racks, their location in 3 dimensions is collected, ensuring that every item is accounted for, inventory placement is known, the contents of every rack is known, and empty slots on shelves are detected for improved efficiency.
Automated mobile robots and lift trucks whose position in the warehouse is known with good accuracy (within inches), in addition to goods carrying RFID tags make this possible.
Keeping track of where trailers and other vehicles are parked in sprawling yards may be challenging. The problem can be exacerbated when carriers park trailers anywhere and workers move them around haphazardly, without recording changes. When distances are large, maintaining visibility into a sizable inventory of trailers can lead to significant inefficiencies.
This can be tackled with a combination of technologies. Identifying these assets, for example, by attaching RFID tags to them when they enter the yard, it is possible to automatically record their location by detecting their presence with a vehicle whose location is known, fitted with an RFID antenna capable of reading the tags.
Behind the scenes
As the descriptions above illustrate, there are many uses of location awareness in warehouse management that become even more relevant with the increase in automation, the use of autonomous mobile robots, the rise of the internet-of-things, and the relentless quest for operational efficiency.
Various location technologies are available, differing in their ease of deployment and accuracy.
When high positioning accuracy is required, visual positioning systems using graphical location markers as reference points are the right choice. For instance, Accuware Visual Positioning System (VPS) delivers mobile device location in 3 dimensions, with average accuracy of a few inches (10 cm) using visual markers that can be deployed indoors and outdoors. This system can be used by mobile vehicles, such as lift trucks and autonomous mobile robots.
Environments where at least 4 or 5 WiFi signals are sensed everywhere enable tracking with average accuracy of 2 meters/6 feet. For example, Accuware Wearabouts for staff (Android phones and wearables) and assets (Smart Tags and Combo Tags).
When the requirement is locating and tracking globally, the first choice is GPS. Except, of course, in GPS-denied areas like “urban canyons”, where GPS satellite signals are heavily corrupted. Tracking staff and assets (e.g. trucks and their drivers) in a mix of urban/rural environment with better than 30 meters accuracy is facilitated by systems that blend GPS and an alternative global positioning system. For example, Accuware Wearabouts used with Combo Tags for either employees or asset tracking.
Combining products whose performance can be characterized for each specific application provides a “location-aware platform” that delivers very practical functionality for today’s cutting-edge Warehouse Control System.