Palletizers and case packers have been the mainstay of robotic applications, according to Sal Spada, senior analyst at ARC Advisory Group (Dedham, MA). "But there's clearly a movement afoot to incorporate robotics into the high-speed conveyor applications where combining trajectory planning with high-speed vision systems enables products to be rapidly sorted off of high-speed conveyors."
Pepperidge Farm is a great example. The company won the Robot and Vision User Recognition Award for its work applying robotics and vision technology successfully in cookie packaging. David Watson, director of engineering, received the award at the Robots & Vision Conference last year, where he highlighted how robots helped his company.
The best way to understand the cookie-packing challenge is to open up a bag of Pepperidge Farm's "Milano" cookies. Lift the top cookie, which is placed flat on top, and see four more cookies on edge in a fluted paper cup. Under the first cup are two more packed with five cookies each in a similar fashion. "Capping cookies, while moving down a conveyor belt running somewhere between 1,200 and 1,320 cookies per min, is quite a challenge for any kind of robotic solution," notes Watson.
To increase line efficiency engineers boosted conveyor speed. "However, the increased speeds made it very difficult for people to manually pick up the product," Watson explains. "So to create a better work environment for employees, and reduce potential exposure to repetitive strain injuries, we use robots." Robots replace direct labor, improve productivity, and even address quality concerns. "People picking up the product over time tend to get chocolate on their hands," Watson says, "which is pretty disgusting and can damage the product."
Pepperidge Farm engineers selected the ABB FlexPicker, a Delta-robot technology set up for very high pick-and-place speeds. "We have used Demaurex Delta Robots as well as the ABB Flexpicker," notes Watson. "But for this project we went with ABB's Flexpicker with its 130-150 pick/min speed range." SIG Pack Systems provided the system and the system integration. ABB provided the FlexPicker robot arms. And Adept, Pepperidge Farm's standard for robot control and vision, supplied the robot controller and vision systems.
Six rows of cookies flow into the robot cells, where they are placed into the cookie cups. The system uses two separate legs, with seven robots on each leg, for a total of 14 ABB Flexpickers. Each robot arm uses two cameras. One locates the product orientation, the other determines product color. Once encoded, the controller determines the speed of the incoming product. An Allen-Bradley interface at each robot cell provides key information to the operators, and stores recipes and other key process information.
Major process components include cup de-nesting, a counter system to tally empty cups traveling in carriers through the robot cells, and the robot system itself. "Cup de-nesting turned out to be one of our biggest challenges on the project," Watson says. "The servo-driven arm that de-nests each cup out of a magazine and places it into the carrier chain uses a vacuum system that collapses the cup before loading it into the carrier chain so that it picks a single cup at a time."
The robot end effector's angled design lets it rotate toward the pick to facilitate edge loading cookies into the cup, Watson notes. "This is a real challenge for that fourth cookie." Filled cups exit the robot cells on the carrier chain, which transfers them into a buffer system at the head of the packaging line. "The project's capital investment of just over $3 million paid back in under three years," says Watson. "And at an internal rate of return of just over 20%."