AGVs embrace adjustable automation

Automation has been credited with many things: reductions in cost, increased flexibility and competitiveness enabling some companies to bring overseas operations back to the United States. It has also been accused of being overly expensive, prohibitively complex and a threat to jobs.

The adoption of automatic guided vehicles (AGVs) in the last few decades has been characterized by the good and bad aspects of automation, but advances in recent years have allowed AGV technologies to break free of conventional wisdom about their drawbacks and potential applications.

This trend centers on the increasing level of ownership an end-user can exercise over its AGV fleet. Early adopters in warehousing and distribution sent a clear message of their frustration with highly engineered solutions requiring extensive investments of time and money in infrastructure, software integration and maintenance.

“Customers want to be able to change their mind almost entirely from day to day,” says Jeff Christensen, director of product development for Seegrid. “If they want to make an adjustment, they don’t want 10 consultants to come out and have it result in a big bill.”

Similarly, customers prefer to perform their own maintenance on AGVs and manage them using their own hardware and software, whether networked industrial computers or Web-based personal devices like tablets and smartphones. AGV suppliers are serving these needs by borrowing ever-more-affordable technologies from the lift truck, automotive and consumer electronics industries.

It used to be that a customer with a fleet of 50 AGVs would need one of the supplier’s resident technicians on site, says Barry Douglas, vice president and general manager for JBT Corp. “Now, they can easily manage that fleet in-house with one employee who might also be responsible for conveyors and other production equipment,” he says. “Five or 10 years ago, you’d have been hard-pressed to find someone in a plant thinking of AGVs as an arrow in their quiver, particularly in warehousing and distribution facilities. That is quickly changing.”

Barriers to entry
The grand vision of AGV applications is also changing. Instead of a one-to-one replacement for the dynamic capabilities of a lift truck and operator, successful AGV deployments target specific slices of materials handling where more basic needs can be met. Investment justifications based on labor savings usually focus on “dead-head” or non-value-added time spent moving materials from point A to point B. As a result, ferrying stock to dock and parts to line in 24/7 applications are among the more common AGV applications.

But, these types of AGV systems can quickly disrupt, or be disrupted by, neighboring technologies, people and processes. A common selling point of AGVs is that they can share usable space with people or lift trucks, offering an alternative to fixed conveyors. These moments of overlap in an unstructured, fast-paced environment are also the places where AGV technologies can falter.

Christensen offers the example of a customer whose AGV system shared a handful of intersections with an automated cart system from a different supplier. “In the past, there were these meetings of two proprietary systems that can’t talk to one another and work on routes established five years ago,” Christensen says. “Some customers found themselves painted into a corner.”

Software solutions from both AGV suppliers and software specialists have come a long way in facilitating communication between equipment and systems of record like warehouse management systems (WMS), enterprise resource planning (ERP) systems and manufacturing execution systems (MES). But the quality of communication between the user and the AGVs is what makes or breaks the system.

“When you buy PowerPoint, you don’t edit the code each time you make a new presentation,” says Garry Koff, president and owner of Savant Automation, as he describes the historic complexity of altering an AGV’s path and any actions along it. Gesture-based and drag-and-drop interfaces have been critical to successfully transferring ownership to the end-user, he says. “It allows them to not only control their own systems, but understand how they work. It’s not black magic anymore done by some software specialist at the vendor.”

Koff adds that the development of natural guidance systems for AGVs is aimed at reducing the further complexity of installing tags, wires, tape or other navigation infrastructure. “Once you get away from that,” Koff says, “you can make changes very easily in the virtual world because so little, if anything, is needed to change in the physical world.”

Amid exponentially increasing pressure to operate quickly and efficiently, AGV owners must have the ability to tweak a system on the fly. “Customers are constantly making adjustments, not just to the AGV system but to the overall plant,” says Terry Shaw, operations manager for Murata Machinery. “Some have schedules that are busy on Monday and Friday but slow in between. They want to quickly change the number of vehicles in use, their paths and their overall workflow.”

Although advances in user interface are promising, and although a budget of $100,000 can get even the smallest users into the AGV game, Shaw cautions against unrealistic expectations. “This technology urges people to change their business process,” he says. “As with any equipment you choose, it goes beyond its mechanical function. It takes time to adjust and to get people in information technology, safety and operations departments involved. Reaching an agreement often becomes the challenge.”

Inventory management
For the most part, stakeholders agree in starting small with AGVs. Whether to reduce labor costs or dependence on a shallow labor pool, many customers start with one or two and aim for a measurable and quick return on investment. Seegrid’s Christensen says there’s time to integrate with a programmable logic controller (PLC) or WMS later, when a fleet is maybe 10 units or larger. At that time, the WMS might even direct AGV tasks, middleware might relay real-time e-mails and messages among personnel, and aggregated data might suggest opportunities for improving a station or process. “If you don’t want to,” Christensen says, “you don’t have to change anything about how you work.”

Savant’s Koff suggests the scalability of AGVs means a facility needn’t be designed for peak capacity 10 years from now. “Potential expansion is not something you need to solidify up front with an AGV system like you do with a conveyor system, which you need to design for a certain rate and capacity,” he says. “With an AGV, you aren’t occupying physical space all the time, only when the vehicle is there.”

In the meantime, AGV users can enjoy the increased inventory control that is a natural byproduct of an always-connected materials handling system. These “soft savings” sometimes produce concrete results, as anyone who has spent a long time looking for a misplaced item knows. “When an AGV picks something up, it gets a time and date stamp before it is stored in the warehouse or sent directly into lanes for shipping same-day,” says Roland Anderson, AGV applications engineer for Amerden. “The maintenance of all those records and first-in, first-out (FIFO) product movement is almost a freebie.”

This might be particularly useful for systems where products go through many operations performed by different stations, Anderson says, where the AGV can keep an eye on progress through each step as well as quality control measures. If equipped with a bar code or RFID scanner, the AGV can deliver to the right destination and remove yet another manual step.

Borrowing from big brothers
One step that will remain manual for some time is AGV unit repair. The maintenance crews in manufacturing facilities are often technically proficient, but that is not always the case in a warehouse. To further empower their customers, AGV suppliers looked to the forklift industry as it transitioned from DC drives to AC drives.

With fewer moving parts, AC drives require less maintenance and less expertise. “And because volumes are higher in the forklift industry, drives and components are less expensive,” says JBT’s Douglas. “They used to be a specialty item. Between that and the falling costs of sensors and electronics in general, a modern AGV’s maintenance costs are as much as half what they were 10 years ago.”

Those same sensors have contributed to more robust safety systems that enable safe operation at higher speeds. In the past decade, Douglas says the average speed of an AGV unit has at least doubled, requiring half the number of units to achieve the same throughput. The vehicle is not necessarily less expensive these days, Douglas says, but the overall system is.

Battery and charging technologies for AGVs have also improved, taking a cue from the automotive industry. Batteries are lighter, require less maintenance and charge much more quickly. “The charge speed is up by a factor of 10,” Douglas says. “Ten years ago, runtime was equal to charge time. Now charge time is just 15% of runtime.”

As proven components migrate from much larger industries into the more modest but steadily growing AGV market, the technology can distance itself from the trappings of highly engineered custom or proprietary systems. Amerden’s Anderson suggests as few as 50% of AGV systems are custom projects. That wasn’t always the case.

In the past, customers and AGV suppliers often talked about what would be possible if “standard” AGV-based solutions could be developed. The lower cost structure offered by a standard solution was considered key to opening up a variety of applications to a financial justification for the technology. But, in practice, most customers desired solutions that behaved differently from process to process or facility to facility.

“Today, that sequence of events is changing,” Douglas says. “Customers now prefer to standardize solutions by designing one plant or process and replicating it in various places. This approach streamlines facility design, vendor selection, employee training and performance comparisons. It also allows for a truly standard AGV design, even if it’s standard only for one customer.”

Companies mentioned in this article
Amerden: amerden.com
JBT Corp.: jbtcorporation.com
Murata Machinery USA: muratec-usa.com
Savant Automation: agvsystems.com
Seegrid: seegrid.com