Articulated slaves

January 10, 2006
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Ever since a Czech playwright coined the term 85 years ago, robots have offered intriguing automation possibilities. Now they're asserting themselves in food plants, with articulated-arm units for palletizing leading the way.

Cases of milk are palletized by Kuka robots at a dairy. With payload capacities exceeding 1,000 lbs., articulated-arm robots are being deployed in a wide range of food and beverage applications. Source: Kuka Robotics Corp.
For thousands of years, the ability to work independently and perform repetitious tasks was the exclusive province of human beings, from construction of the pyramids to the Industrial Revolution. By the late 20th century, robotic machines started performing monotonous duties, though high costs and a lack of flexibility minimized their application in food and beverage manufacturing.



Fortunately, the situation is changing, led by articulated-arm robots for case packing, palletizing, depalletizing and other material-handling applications. The shift is due in part to a manufacturing environment where menial jobs are hard to fill and lean manufacturing encourages the use of machines for non-value added jobs. Another factor is the maturation of robotics technology and advances in complementary technologies. According to a recent survey by the Packaging Machinery Manufacturers Institute, 35 percent of manufacturers plan to purchase robots this year, with palletizing robots the most likely application.



A high degree of flexibility was engineered into robotic case-packing machines for meat commissioned by IBP eight years ago and designed and built by Foster-Miller.
Articulated-arm robots were an immature species a decade ago, though their need already was apparent. Only the largest processors could consider robotics initiatives, and the solutions required customized engineering. A leader in the effort was IBP Inc., which had 34,000 employees at the time. Dick Bond and Gene Leman, heads of IBP's fresh meats and allied group, respectively, recognized that the pool of workers willing to perform repetitive, health-compromising tasks in a cold environment was shrinking to unsustainable levels. Food safety was a growing concern, and automation was a way to address it while also easing the labor crisis. Unfortunately, the available solutions required unrealistic alterations to plants. Bond and Leman went outside the industry and hired Larry Fallin, a mathematician who served as a process expert in identifying and commissioning automation and robotics projects that could operate in existing plant layouts. "And if you create space, you're a hero," remembers Fallin, who joined IBP in 1996 and now serves as director of integrated automation systems at Foster-Miller Inc., Waltham, MA.

"It wasn't a matter of getting rid of the labor; the labor was disappearing," Fallin adds. "The repetitiveness of some of the work was an ergonomic nightmare."

Two dozen potential initiatives were identified in Fallin's first six months on the job. Robotic loin trimmers and a self-sharpening blade using technology from Sandia National Laboratories were rejected as too pricey or impractical for deployment. An automated squeezer of pig intestines produced chitlins too clean for customer expectations and was scrapped. The project eventually focused on the packaging area as a prime candidate for robotics.

In 1997, Fallin began working with Andrew Courier, a design manager with Foster-Miller Inc., on a robot capable of packing a wide variety of primal cuts into shipping cases. The cuts arrived in a pack-off area in vacuum bags and had to be oriented to customer specifications, typically with a target weight of 100 lbs. per box. End effectors such as suction cups and pneumatic claws were defeated by the cuts' random shapes and weights and by the package material. After studying the way operators packed, the engineering team developed a bucket with four axes of movement and an air bladder to secure each piece. "The (bucket) elevator goes up and down and tilts for a sixth degree of freedom," says Courier, a mechanical engineer. "The algorithms for queuing, sorting and orienting each piece resulted in a fare amount of autonomous intelligence."



Detail of the bucket that secures and orients primal cuts for packing. Source: Foster-Miller Inc.
The system's modular design allowed deployment to eight different plants, beginning with IBP's Amarillo, TX, facility in 1999. "We took advantage of ceiling height to turn a packaging station that was horizontal and made it vertical," says Courier, requiring less space than the displaced workers. A bigger challenge was speed: from four pieces per minute, the design team was able to optimize performance to eight pieces.

While observing the workers, the team noticed they relied on touch rather than sight, which inspired engineers to install sensors to orient and handle the cuts. "Vision systems have their place," says Fallin, "but they don't have the cognitive ability of the human brain. A vision system can't generalize."



I can see clearly now

The engineering required for IBP's Robo Packer is beyond the means of many food and beverage manufacturers. Fortunately for those firms, standardized robots requiring simplified programming are becoming more common. The articulated arm robot is emerging as the system of choice for moderate speed, multi-line palletizing, replacing gantry style robots. By adding sufficient lighting and an affordable vision component, articulated arms are being applied to depalletizing, though palletizing robots outnumber those applications by a factor of 10 to 1.



An automated guided vehicle (foreground) awaits a completed pallet being assembled by an articulated arm robot. With integration costs declining, these automation solutions offer flexibility and a quicker ROI. Source: QComp Technologies Inc.
Robotic vision remains a solution of last resort for most integrators. "We use vision with flex pickers, but our first choice is to do projects without vision," says Thomas J. Doyle, president of QComp Technologies Inc., Greenville, WI. "It's simpler and less expensive."

"Vision systems add a level of complexity, there's no doubt about it," agrees Tim Schiller, key technology manager-robogistics at Clinton Township, Michigan-based Kuka Robotics Corp. "But vision adds a lot of power and flexibility, and unless you're getting involved in meat cutting, vision systems work well. And calibrating a camera for a robot is getting easier and easier."

Digital cameras compute pixels, while a robot relates to the world in millimeters. Translating those dimensions required significant engineering in years past; now plug-and-play solutions are surfacing. Additionally, some cameras can be cabled directly to a robot, eliminating the need for a separate processor for the camera. And today's processing power is magnitudes greater. "In the old days, you ran out of (computing) room if the robot had to process more than 500 kilobytes," says Schiller.

"Machine vision using stills and surveillance technology using moving images are coming together to allow manufacturers to track items coming down a (conveyor) line," says Dave Holland, a production manager at Fonterra Cooperative Group Ltd., a New Zealand dairy that deploys 1,283 PLCs in its facilities and has a controls infrastructure valued at $320 million. Fonterra has started using cameras with articulated-arm robots for depalletizing. Digital cameras also are being incorporated into automated guided vehicles (AGVs) to store and retrieve inventoried product.

Fonterra abandoned gantry systems 10 years ago and embraced articulated arm units because of their lower capitalization costs, pattern-forming flexibility and reprogramming advantages, Holland said in a presentation at last year's Worldwide Food Expo in Chicago. The company now has 60 such robots, including a two-robot, 10-lane system recently installed to palletize 55-lb. cases of butter. "It's a complex system that replaces 10 people and handles up to 1,200 boxes an hour," he said. "It's also rugged: the parts that tend to break down are the conveyors and box handling equipment, not the robots themselves."



Vacuum cups have proven to be very versatile end effectors for robotic palletizing systems, but a shift toward more display-oriented shipping cases is driving development of hybrid vacuum/claw attachments. Source: Columbia Okura LLC.
Incorporating AGVs with robotic palletizing was an exotic and expensive option five years ago, but not today. Open software and declining capital costs are narrowing the price premium over conveyors, and the increased functionality and flexibility more than justify the investment, maintains QComp's Doyle. "It takes a while from the time you plant the seed for AGVs until you write an order for them, but using AGVs with robotic palletizers requires a smaller footprint and can be less expensive than conveyors with transfer carts," he says. "They're also safer: the safety issues I see in plants are people walking on conveyors."

QComp integrates ABB robots with a Danaher controls platform used "in tens of thousands of AGVs worldwide," Doyle says. Logic embedded in the program simplifies reprogramming of the AGV's path. Laser-guided systems offer the greatest flexibility. The lasers send a signal every 50 milliseconds to wall-mounted reflectors to triangulate their position and stay within one-quarter inch of trajectory. Speeds of up to 3.5 ft. per second are attained.

While OEMs emphasize the flexibility of articulated arms, they acknowledge the limiting nature of end-of-arm effectors. "That is the make or break of a palletizing robot," notes Laxmi "LP" Musunur, engineering manager of palletizing and packing at Fanuc Robotics America, Rochester Hills, MI. "That is where a good systems integrator comes in."

About 80 percent of robotic palletizing involves corrugated cases. Vacuum effectors are great for corrugated, but club stores and other retailers are demanding display-ready cases. "There is a move away from vacuum technology because so much food and beverage product is shipped in trays and shrink bundles today," points out Pat O'Connor, product manager-palletizing systems at St. Louis's FKI Logistex NA. Fork-and-clamp tools provide more positive grip and lift, though the trade-off is slower speed.

One solution is a hybrid effector, which achieves 20 cycles per minute, Musunur suggests. Mechanical assists counteract the lateral shear from rapid acceleration and deceleration that can defeat a suction system.



Baby, it's cold inside

Ice cream freezers and other cold environments are a logical application for robots, though most freezer palletizing continues to be done manually. One factor retarding robotics was the slow development of customized solutions. Metallurgy is "at the critical edge" when temperatures reach -20°F, says Paul Probst, president of von Gal Co. in Montgomery, AL. Gearboxes draped with heated blankets still are being deployed. "You're paying for the energy three times: once to heat the blanket, and two more times to remove the heat because of the thermodynamic efficiencies," he moans.



Two lines of corrugated boxes and pails are served by this FKI Logistex system. In a low case-output environment, a single robot is serving 30 lines in one plant. Source: FKI Logistex.
Like most of today's automotive-grade OEMs of articulated arm robots, the Kuka units von Gal integrates have been modified for -22?F freezers. Gearboxes and drives are modified to compensate for metal contraction. Low-temperature lubricants and seals are used, and cable connectors that won't become brittle in extreme cold are in place. "You can't bring these robots into an ambient temperature area and expect them to run," allows Kuka's Schiller, but dependability in the freezer is greatly enhanced.

Incremental changes like freezer-specific robots and carbon-fiber forearms for longer extensions without excessive arm weight will pave the way for more food applications, says Probst. Familiarity with palletizing robots also will increase use. He likens robots to servo motors. In 1976, Probst installed the first servo for a computerized bologna slicer in Oscar Mayer's Davenport, IA, plant. "That was scary, state-of-the art technology at the time," he recalls. "Now it's commonplace." The same maturation is underway with robots, with articulated arm palletizers playing the role of servo-driven bologna slicers.

For more information:

Rick Goode, Columbia Okura LLC,
360-735-1952,
ricgoo@colmac.com

Laxmi "LP" Musunur, Fanuc Robotics Corp.,
248-377-7940,
laxmi.musunur@fanucrobotics.com

Pat O'Connor, FKI Logistex,
314-993-4700

Andrew Courier, Foster-Miller Inc.,
781-684-4000,
acourier@foster-miller.com

Tim Schiller, Kuka Robotics Corp.,
810-533-2961,
timschiller@kukarobotics.com

Tom Doyle, Qcomp Technologies Inc.,
920-757-0775,
tdoyle@qcomptech.com

Paul Probst, von Gal Co.,
334-261-2777

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