With operations increasingly unable to staff adequate labor to achieve their goals for higher throughput and productivity, more companies are turning to autonomous mobile robots (AMRs). These intelligent mobility platforms help warehouse operators automate various tasks—especially the movement of goods—in an efficient, cost effective, safe and collaborative manner with minimal human intervention.
“Most implementations with AMRs are intended to increase productivity by reducing the amount of time workers spend walking from task to task,” noted Clint Reiser, director of supply chain research at ARC Advisory Group, who noted that different AMR manufacturers have designed a range of robot styles for various applications.
Some AMRs travel between associates stationed in specific areas to drop off items for put-away, or to collect the picked items for transport to consolidation and pack stations, Reiser explained. Other AMRs follow a single associate through their picking path and stop at an item’s storage location for the pick; as the first robot takes away completed picks, a second takes its place. Still others present totes or shelves of items to associates for picking in a goods-to-person methodology.
“The advantage of all these approaches is that workers no longer have to push a cart throughout the facility; they stay focused on picking instead of walking between zones,” he said. “Currently, that’s where AMRs are delivering the biggest value, by minimizing worker travel time.”
How the AMRs know where to go is determined by software. Which software (or combination of softwares), however, depends on the type of operation and the level of technology investment already in place, said Dr. Paul Rivers, CEO of guidance automation, a part of MHI member Matthews Automation Solutions. He described four primary types of AMR applications:
- Manufacturing facilities using AMRs for closed-loop delivery between a warehouse of kitted parts to line-side production workers.
- Fully manual order fulfillment operations that do not have a warehouse management system (WMS) and for whom an investment in AMRs is their first foray into automation.
- Operations that have a WMS and maybe some limited investment into other automated systems adding AMRs to cut worker travel time.
- Companies adding AMRs to an operation with multiple automated systems directed by an overarching warehouse execution system (WES) to synchronize and orchestrate equipment and labor workflows.
Integrating AMRs without warehouse software
Investing in a fleet of AMRs includes two things, noted Ed Romaine, vice president of marketing and business development at MHI member Conveyco.
“When you buy an AMR, you’re getting both the hardware, which executes a task such as retrieving, storing or transporting inventory, and the controls and proprietary software,” he explained.
The fleet management software, or robot control software as it’s also called, makes many of an AMR’s operation decisions, such as routing, maintenance and charging. The software controls the robot in real time, moving it in an efficient manner through the facility, Romaine continued. “The AMR control software optimizes individual robot tasks, status and location. It also collectively optimizes the fleet’s distribution throughout the facility to minimize traffic.”
Thanks to this layer of software controlling the robots, a fairly simple operation does not need a WMS or WES to benefit from the deployment of a fleet of AMRs, Rivers said.
“In a manufacturing operation, where there’s a lot of repetition from stores to production, the robot is simply instructed to go back and forth between the two,” he explained, adding that the same holds true for manual picking operations lacking a WMS.
“Certain fleet managers are increasingly incorporating limited inventory management capabilities,” noted Rivers. “That makes it possible for an order fulfillment operation with lower stock keeping unit (SKU) counts to deploy AMRs without having a separate inventory management system, and still benefit from reduced worker travel.”
Integrating AMRs with WMS
Operations with an existing WMS that are adding AMRs can do so relatively easily, even those with legacy or homegrown software that has been in place for decades. Integrating the WMS with the AMR fleet manager simply requires a layer of software between the two that translates commands to facilitate communications. According to Rajabahadur V. Arcot, senior advisor at Quadrant Knowledge Solutions, there are many ways to do this, such as the following:
- Application based integration, which involves developing software that enables the independent applications to work together by making their data compatible with each other.
- Middleware data integration utilizing software developed to connect the applications and enable exchange of data between them. The software facilitates communication, application execution and monitoring.
- Common storage integration, which transforms and copies data to a common, single source database where it is accessible by any systems involved in running the applications.
The benefits of integrating AMRs with WMS are multi-fold, Arcot said.
“A WMS gathers, stores, analyzes and shares data associated with inventory, storage management, order processing, and so on. The tasks performed by AMRs—such as receiving and put-away of goods, picking of orders, their shipping and more—are directed by commands generated by WMS,” he explained. “The coordinated working of AMRs and WMS is essential to maximize the benefits of automating the warehouse operations.”
Rivers agreed. “The WMS knows where all the inventory is. It tells the AMRs, through the communications software connecting the fleet management system and the WMS, what jobs to perform. The fleet manager figures out how to move the vehicle around to complete those tasks most efficiently,” he said.
For example, described Rivers, the fleet manager knows multiple AMRs are already in a specific aisle. It will therefore route the next robot with a WMS-directed task in the same spot elsewhere first to avoid traffic, then send it back when clear. It will also determine which AMR is in the optimal location to take on the next set of WMS-assigned tasks in a certain zone—even if the robot won’t be available for another two minutes—rather than send a free AMR on the other end of the facility to do it.