Lessons from a Bow-Tying Robot

chocolate box

Robots with the proper industrial motion control systems can do some amazing things, producing paper cups at a phenomenal rate or maneuvering heavy car parts into precise placement in seconds. But some actions are just too hard for robots. Getting a robot to open a door (by turning the handle, not just crashing through) or fold laundry is incredibly challenging, even though human children can learn these tasks easily.

So we have to be impressed by the bow-tying robot a Midwestern candy maker came up with.

This high-end candy comes in a box tied with a ribbon. Human beings can tie consistently great looking bows at a rate of about five per minute at best, but they can’t keep it up all day. Tying as many bows as they can during the day while trading off with other tasks still puts human workers at risk of repetitive motion injuries and carpal tunnel syndrome. Slowing down to three boxes per minute doesn’t help much with the safety and wellness issues — and it makes an enormous difference in productivity.

Obviously, this is a job for automation. Precise, consistent bow tying by an untiring machine with the capacity to perform repetitive actions without pain or boredom is a perfect example of better life through automation.

It wasn’t easy. Six axes of motion are required to tie a bow, and the space available didn’t allow the first robot the company tried to use its full range of motion. This machine was producing fewer than one bow per minute, and the bows weren’t consistent.

aXatronics and Yaskawa Motoman used 3-D simulation software to come up with much more precise programming and a much smaller robot. The new robot had a reach of 0.64 cm beyond the required movements, and it could move its robotic arm into all the angles a human arm uses to tie a bow. Servo controlled carriers fed boxes to the new robot, and the simulations allowed thorough testing of the various ideas engineers came up with before building the machine.

The robot can only tie two boxes per minute, which is not nearly as fast as the fastest human workers, but it can tie those bows steadily for 12 to 14 hours a day.

3-D simulation is obviously key to the happy ending for this success story, but it illustrates more than the importance of the new technology turning up in industrial motion control and robotics. It’s the problem-solving ability of humans that really stands out here, the creativity of the people figuring out how to use the robots.

Along the way, servo motors continue to be the essential element. However groundbreaking the machine, the technology that makes it possible relies on this type of motor, which has been around for more than a century.

If you’re using Rexroth electric motion control solutions, we can help you keep them in service. We often work with servos than are older than the people who call us for help. Legacy or new, Rexroth motion control units are what we know best.

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