How robots can run a warehouse
In a previous article (“The People-less warehouse”), we looked at automated equipment for storing and moving items in a warehouse, but nothing along the lines of robots.
Developed and nurtured for repetitive-task, high-volume manufacturers, the use of robots and automated equipment in warehouses is in the very early embryonic stages of utilization. Only a few high-cube, high-volume warehouses use robots to put away and pick items, and aggregate items for shipping. It is the wave of the future; another step toward the almost people-less warehouse. Before looking at the details of warehouse robots, let’s take a brief refresher course on automation.
While contemplating the use of automation, remember proper warehouse organization and the procedures and controls followed are the foundation for effective operations. The less automation involved, the greater the need for organization and discipline.
Automated non-robotic equipment is used for storing, retrieving and moving items, but is fixed in place and can only be programmed to a limited degree.
Conveyor: Powered-belt and roller conveyors, for example, move items, cartons or reusable containers horizontally, downward or upward. Manual roller conveyors are unpowered. If horizontal, people push things along; if it slopes downward, things move under the force of gravity. A conveyor can be manually loaded by some other equipment or a robot.
Sorter: This machine either can direct something to one of several conveyors or drop something into the proper carton. A sorter can be manually loaded by a conveyor or a robot.
Automated storage and retrieval system: Think of a row of shelves and a driverless lift truck running parallel to the shelving, controlled by signals coming from wires buried in the floor. Software controls the lift truck, directing it to the system-selected bay and slot. It’s then directed to the designated level where the pallet is eased by the forks into the storage slot. For picking, the process is reversed. There are other kinds of ASRS devices, such as a carrousel.
Automatic guided vehicle: This typically is a battery-powered, low-height motorized platform that follows wires buried in the warehouse floor. The wires can be located in one or more aisles, so an AGV can travel throughout a warehouse. Special software determines the exact path taken when putting away or retrieving something.
A robot does not look like a person. Some warehouse robots look like a box on four wheels with recessed metal “arms” that can extend out and grab around or under a carton and pull it out. Other robots look like a pole with articulated arms that can grab, lift and maneuver boxes.
Unlike automated equipment, a robot can contain vision technology, enabling it to “see” the shape of something to be handled (even in low light), and if needed, adjust its speed, direction, etc. A robot can contain “touch” technology. It can sense irregularities or problems with an item and can adjust its “behavior.” Each robot wirelessly communicates with a central computer providing basic directions to it (at times, based on feedback from “seeing” and/or “touching” something), controlling automated equipment, and integrating and coordinating the actions of the robots and automated equipment.
A picking robot can retrieve a box or piece and place it on a conveyor or sorter, as commanded by the central software. The latest picker robots can pick and place 100-lb. boxes in a few seconds and do so almost 24/7 (though time usually is scheduled for daily preventive maintenance).
A loading robot can use its arms, vision and central software directions to aggregate boxes to a pallet, orienting each box to obtain a profile that will not cause problems downstream, such as at an automatic shrink-wrapping machine. The result is one box every few seconds almost 24/7. The pallets may be placed on a conveyor that takes them to a truck or on a forklift driven by a human.
Robots can be individually programmed. If more are needed to perform a peak-load task, such as unloading trucks, only a few minutes are needed to reprogram them. When another task arises (such as picking), a quick reprogramming results in different skills being performed. Robots can be re-programmed to handle any new changing requirements.
Multiple robots can work very close to each other without slowing down. In one warehouse, a multiple-mezzanine arrangement enables several robots to simultaneously work on each level; picked items are placed on a dumb-waiter-like elevator for movement to automated equipment or another robot.
Working in unison
Let’s look at how robots and automated equipment could work together in a warehouse. At receiving, manned forklifts move pallets from inside trucks to a powered belt conveyor. At the end of the belt, a sorter determines which secondary conveyor belt to use. A robot then grabs a box, reads its barcode or RFID information, transmits the information to a computer and follows directions from the computer as to where to put away the item. Think of a line of closely-spaced robots, each grabbing a box from a secondary belt and putting it away. Similarly, a line of several robots would pick items, from one or more locations in the warehouse, and place them on a conveyor or sorter that feeds other conveyors.
Warehouse management system software plans and manages the arrangement and activities of a warehouse. It determines where to store items to be received on the next business day based on purchase orders and customer-order data. After items are received, it determines where to store an item, tracking how much of each item is stored in each slot. A WMS also does higher-level labor planning (e.g., how many people to bring in for a particular day and shift). Most WMS functions do not work in real time. However, as soon as data about a picked item is captured, the WMS updates slot-specific and item-level logistics. The WMS also interfaces to systems of vendors (e.g., receives advanced shipping notices).
A warehouse control system is software that controls the physical activities of automated equipment and robots, such as starting and stopping conveyors and sorters and directing a robot to perform a specific task at a specific location. A WCS works in real time, using both data it acquires (e.g., status of a piece of equipment read from a barcode on an item/carton) and data transmitted by the WMS.
A WCS can control the speed of a particular unit and robot in order to balance loads on specific equipment/robots and through the warehouse. It also makes
real-time adjustments (e.g., when a jam at a sorter is detected the WCS would stop those upstream activities that would result in other jams).
A WCS also assigns and manages labor. When a packer logs out, the WCS will determine which other suitable people are available and assign the function to one of them.
Getting ready for robots
Pros: Robots, like automated equipment, reduce warehouse headcount and related costs, eliminating back injuries caused by constant lifting. No need for rest breaks and no worry about turnover among warehouse workers. The use of robots can dramatically decrease the amount of warehouse cube needed to store a given set of items/cartons/pallets.
Although not as flexible as humans, modern programmable robots are much more flexible than automated equipment. Limited flexibility is one reason automated equipment hasn’t exactly set the world on fire.
Robots also create high-paying warehouse jobs. People are needed to program robots, as well as maintain and watch them in case something goes wrong (like a case is dropped).
Cons: The cost of the robots and the warehouse environment needed for them to effectively function is very large. It’s all custom-designed and -constructed. Yet, as the cost-effectiveness of technology advances, the cost of the robots is decreasing at a rapid rate.
It’s going to be a long wait for 99.99% of distributors, so act now to reduce warehouse costs and prevent costly mistakes. Some improvements can be done quickly and at little or no cost. Look at your warehouse organization, procedures and controls.