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Dad, can’t you build a machine that can juggle?

06 July 2010

Martin Harms works at the Lenze Application Centre in Hameln, Germany. At supper his children Ole and Birthe often ask what he does at work. He explained to them how he automates machines. His son and daughter suggested he put his efforts to more practical goals—machines that automatically butter bread, clear up the play-room — or that juggle.

Left: “Jongliermaschine“ at Hannover Fair; right: creative thinkers Ole and Birthe Harms
Left: “Jongliermaschine“ at Hannover Fair; right: creative thinkers Ole and Birthe Harms

Electronic cams can produce precise, fast processes that preserve the mechanical components,especially in packaging machines with their cyclically repeated movement profiles. At drive and automation specialist Lenze, two children saw to it that the benefits of this type of motion control can be seen by all at trade fairs in an exciting, tangible form.

Hands as drives
That was it, thought Mr. Harms. It was an idea that could present the powerful cam technology of Lenze’s L-force Servo Drives 9400 in an exciting, attractive form at trade fairs and exhibitions.

Juggling, after all, is the coordinated movement of two hands — or drives. The high motion cycle frequency involved in juggling is also similar to many industrial cam applications. And, catching and throwing balls is a perfect task for electronic cam groups.

Despite some initial smirks from colleagues, Michael Beckmann, who is responsible for trade fairs, decided to risk the unusual project and make the “Jonglator” (a word made up by Mr. Harms daughter, Birthe) into reality.

Wish becomes reality
It may have looked simple and elegant at its premiere at Hannover Fair in April 2008, but it was the result of a lot of meticulous fine-tuning.

Martin Harms began by defining a juggling pattern, and used to it calculate motion profiles for the electronic cam drives.

On this basis, Markus Kiele-Dunsche set up simulations on a PC and worked out the sizes of the drive axes that would be needed. They are made up of four Servo Drives 9400 and four synchronous servo motors from Lenze’s MCS series, each connected to linear axes.

The Jonglator is therefore a typical use of cam drives that work in conjunction with one another in industry.

Throw patterns also had to be designed in Lenze’s Engineering software so that the throwing distance and height would suit the dimensions of the machine.

The L-force Engineer’s cam editor performed brilliantly, especially when it came to the ultra-precise matching of inter-related movements and cams.

Another challenge was the starting moment. Originally it was planned to feed the balls one after the other into the right-hand catch-basket using a conveyor screw. But this concept was too inaccurate; some balls were sent too early, some too late – and so they missed the catch-basket. The solution was a transparent ball magazine with three precision- switching compressed air flaps. The valves for the compressed air are controlled by the integrated cam control unit in the Servo Drives 9400.

You can view a video clip of the Jonglator in action at Hannover Fair 2010 (with some cool jazz music) here.


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