Debra Schug, Contributing Writer
While the thought of autonomous cars dominating roadways still amazes the general public, automated guided vehicles (AGV) have been used by businesses for decades. The newest models of AGVs have come a long way since their rudimentary introduction as essentially a tow truck following a wire on a floor performing very simple movements.
Today’s systems consist of one or more computer-controlled, wheel-based load carriers, typically battery powered and running on smooth surfaces without an onboard operator. Some AGVs move over defined paths, guided by devices such as buried inductive wires or mounted magnetic strips. Some of the more sophisticated models navigate by lasers, and the leading-edge technology is free navigation.
This article will take a look at how AGVS can help material flow in a facility; the different types of AGVs; and special considerations to keep in mind about ROI and maintenance needs.
AGVs for Modern Material Handling Challenges
Operations looking to upgrade their material flow have plenty of reasons to invest in AGVs. More conventional ways to move product in facilities typically involve manual labor with people either doing the moving or operating lift trucks to do it. However, with extra hands comes extra labor costs, and in today’s tight labor market, especially in the manufacturing industry, finding workers can be challenging.
Also, workers need to take breaks and time off, sometimes unexpectedly. But with AGVs, workflow and material movement is much more predictable and at a consistent speed. Keith Soderlund, Vice President of Sales for Creform Corporation, said one of the biggest benefits of having AGVs is the repeatability that comes with automation. “This includes positioning accuracy as well as schedule accuracy,” he said.
Additionally, human operators can make mistakes when operating forklift trucks, which can cause accidents resulting in damage to equipment, building structures and even people. Soderlund said AGVs are much safer, because they run at a reasonable speed and have built-in safety equipment to protect products, as well as surrounding personnel.
In fact, the AGVs industry group, Material Handling Industry of America (MHIA), announced in 2012 the release of ANSI/ITSDF B56.6-2012 Safety Standard for Driverless, Automatic Guided Industrial Vehicles and Automated Functions of Manned Industrial Vehicles. This was developed under the American National Standards Institute (ANSI) and is used to guide safety requirements for system suppliers, manufactures, purchasers and users for the design, construction, application, operation and maintenance of unmanned guided industrial vehicles and automated functions of manned industrial vehicles.
“All AGVs need to have visual and audible warning devices,” said Soderlund. “In addition, they need readily accessible E-stops and safety bumpers.”
An alternative option to automated material flow without AGVs is a conveyor system, but this equipment can be more expensive and difficult to install compared to AGVs. Plus, conveyors can do damage to the plant floor.
“Conveyors tend to chop up the floor, making it difficult to move from one area to another. Some people raise them up high then maintenance is more difficult. Conveyors also are hard to reconfigure,” Soderlund stated.
In comparison, AGVs keep the floor space more open and can be more easily changed with modification of the guidepath. Also, because AGVs can easily be bought and sold, operations can stay more flexible and change with the capacity and demand needs.
Additionally, because AGVs can be a part of a bigger automated system, they can provide greater transparency into the flow of materials in a warehouse, said Laura McConney, Marketing Specialist for JBT. Data insight provided by AGVs can contribute to increased productivity and efficiency of a facility by reducing redundancies and time wasted.
“AGVs consistently deliver materials and track these deliveries throughout the warehouse,” said McConney. “There’s no waiting for a fork truck driver to arrive or wondering if something has been moved. AGVs simply pick up loads when they need to because the system communicates directly with equipment and/or higher-level software, like warehouse management systems.”
The Categories of AGVs
There are a number of different AGV groups, which include unit load, automatic guided carts (AGCs), tow or tuggers, forked vehicles and custom vehicles. Here’s a quick description of each:
Unit load AGVs: These vehicles are sometimes called “top carriers” and most closely resemble those AGVs first introduced in the 1950s. Essentially, a unit load AGV is a powered, wheel-based transport vehicle that carries a load, such an automobile part or a group of items on a pallet or in a tote.
Automatic guided carts: Automatic guided carts are guided by magnetic tape on the floor and are ideal for moving products on an assembly line or transporting goods throughout a facility.
Tow or tuggers: Towing or tugging AGVs are ideal for pulling wheeled carts and can typically haul more loads per trip than other types of AGVs.
Forked vehicles: These are usually the more flexible category of robotic vehicles. Forked AGVs offer a rugged, adaptable solution to material handling challenges.
Custom vehicles: Some manufacturers provide special application AGVs to help address a customer’s specific material handling challenge, such as moving cumbersome items and wide industrial rolls.
With all of the above types of AGVs, there have been a number of improvements made to modern models. First of all, they have become more affordable than in the past and safer. Plus, better controls and software available have made them easier to program and can be centrally controlled.
“The software that controls the vehicles features powerful reporting tools that help users to determine where hiccups in their operations may occur,” commented JBT’s McConney.
Also, new types of batteries and charging options, including fuel cells, inductive power, Lithium Ion and more have improved powering AGVs, making them faster to charge with less frequent recharging need.
The best type of AGV is contingent on the job that needs to be done in a facility. Some of the jobs that AGVs are well-suited for are line side delivery of parts, assembly, material movement and removal of trash.
“Applications in a warehouse environment that are best suited to AGVs include really anything that’s very repeatable,” said McConney. “Material movement from receiving to storage and storage to outbound are strong contenders for automation.”
Maintenance of AGVs
As with most equipment, AGVs will need a certain amount of onsite maintenance to ensure longevity. Creform’s Soderlund suggested having a small stock of critical spare parts on hand to respond rapidly to any maintenance needs of AGVs.
“Once you integrate AGVs into your operations, you’ll be counting on them to be up and running consistently,” he said.
Preventive maintenance programs can address most issues before causing a disruption, he added. Involving a facility’s internal maintenance and tech support when first obtaining AGVs can help keep them running longer.
But, with AGVs offering the many benefits of increased safety, efficiency and flexibility, maintenance needs can be factored into the ROI and still produce a payback in typically two to three years. The payback period, said McConney, is based on the amount of time that the facility operates. So for more active operations with multi-shifts, the more likely the payback will be achieved within three years. WMHS