NU inventors make assembly line safer

Cobots, unlike typical robots, don't have motors and can't run by themselves. But they could revolutionize auto construction.

By Ivy Bartholomew
The Daily Northwestern, April 8, 1997

A new invention from Northwestern engineers could transform the way auto workers assemble cars.

Two NU professors and a graduate student have developed devices called cobots, which will help auto workers easily guide heavy components into cars, reducing the chance of collision between the parts. Cobots aren't stereotypical robots as seen on "The Jetsons." They don't walk and they don't talk on their own. Cobots, or "collaborative robots," need a human hand to move.

"Cobots are intelligent assist devices designed to help workers in the auto industry," said Michael Peshkin, co-inventor and mechanical engineering associate professor. "They take the weight of the part off workers and provide guidance, allowing them an easier way to maneuver parts into cars." On an automotive assembly line, workers must maneuver and attach large and unwieldy parts, such as seats, instrument panels and doors, without damaging the auto body, Peshkin said.

Currently, workers only have access to traditional hoists that reduce the weight burden but add bulk that increases the chance of collisions between the cars and their parts, he said.

"They are more trouble than they're worth," Peshkin said. "Cobots, however, offer support against gravity and provide needed guidance." Cobots offer this guidance through the use of virtual surfaces, which are determined and controlled by a computer, said Witaya Wannasuphoprasit, an NU graduate student who built the department's only two cobots. "Cobots have an invisible boundary you can't penetrate," Wannasuphoprasit said. "Their virtual surfaces don't allow them to pass a certain line." Although workers are free to move the cobot within virtual surfaces, once the cobot approaches the boundary line its wheels automatically redirect themselves. No matter how much force is applied, the cobot will never pass a virtual surface, Peshkin said.

"The cobot will push back on you if you go in the wrong direction," said Ed Colgate, co-inventor and mechanical eng ineering associate professor. Cobots that will be used in an assembly line have three wheels. The first three-wheeled cobot, named Scooter, took Wannasuphoprasit six months to build and was completed in September 1996. Scooter is a sturdy, low-to-the-ground triangle with an in-line skating wheel at each corner. Each wheel remains firmly in contact with the ground at all times.

In-line wheels were chosen because of their ability to redirect the motion of a 200-pound skater in a fraction of a second, Peshkin said. Each wheel is independently steered by the computer. Because cobots depend on the help of a human to move, they will never be able to replace workers, Colgate said.

"Cobots are not like mechanical men," he said. "Making a mechanical-man robot is not something we want to do nor can do. It's more important to help people, not to replace them. People bring so much to the table and can deal with exceptional circumstances very well. Cobots exploit that idea better than anything else out there." Cobots also are safer than robots, Peshkin said. "Industrial robots are dangerous," he said. "Workers know that. Workers don't want to come in close contact with them." Cobots also might have a future outside of the automotive industry, Colgate said.

"They will serve an important role in the textile industry," he said. "We are also looking at how a cobot can help in computer assisted surgery."