A Gripping Tale

2007-11-01: One of the keys to the advancement of robotics is the development of new and innovative grippers. Welcome to the future. Advancements in robotics are about doing more with less, and about copying human arm movements for maximum efficiency. But robots do more than human arms can – they lift more, faster and tirelessly. Greater flexibility, lighter weight materials, new technical advances in sensors, a finicky retail environment where purchasing managers are buying less but more variety (mixed palletizing), and a move into new industries like food processing (hygienic design) – these are some of the dominant trends in robotic gripper technology today.

Ancient laws of geometry

The laws of geometry have not changed since the Greek mathematician Euclid wrote them down in The Elements in 300 BC, and they remain the basis for how today’s robots and their grippers function. After all packaging is all about fitting something into a box, and geometric principles dictate how many can fit.

But gripper technology has come a long way since the days of Euclid, with literally hundreds of different solutions for all imaginable industries. And in most industries, there is an increased pressure to come up with cost-saving alternatives to increase profitability.

This is what is driving developments in robotics and gripper technology as automated tools for packaging and sorting find their way into new applications, or move upstream into production.

“The human hand is the most flexible tool you could ever think of,” says Dr. Andreas Wolf of robomotion, a robot technology consultancy in Germany, and author of the definitive book Grippers in Motion. The book provides a comprehensive guide to automation processes involving gripping and manipulation.

“But unfortunately, robotic hands with all their sensors, joints and flexibility tend to be very expensive, and not every process needs the flexibility of a human hand,” says Wolf. “At the moment most industrial manufacturing that uses robots tend to have a dedicated gripper for the task.

“At the same time, the intelligent gripping systems and service robots that we have today are the early signs of a new, more flexible automation technology, which will be capable to auto-adapt to changing environments. Applications in the food processing industry, pharmaceuticals and agricultural production are not yet standard, but they do offer a growing market for automated solutions in the near future.”

Sophisticated tools

As an example of grippers that can adapt to their environment, researchers at New York University’s Courant Institute have developed a new kind of gripper they describe as reactive. It responds to stimuli from its sensors they way a hand would from nerves, and changes its grip accordingly.

But in general, the size and shape of robotic grippers depend in great measure on what it is that they are intended to grip. There are grippers that stack, grip, suck, force-fit, or form-fit, single grip or multi-grip. Some are purely mechanical. Others use vacuum technology.

And as consumer goods manufacturers are increasingly making products in every imaginable shape, material and size, the robotics have to become increasingly sophisticated.

“Cycles are going faster and faster today,” says Peter Tell, PIAB’s Chief Technical Officer who invented the coax multistage vacuum cartridge ejector system that is particularly suited to object picking and palletizing. “Every manufacturing company wants to increase production at a lower cost. It is about doing more with less.”

A well-known paint and coating manufacturer in the U.S. installed a coax system on one of its packaging robots and has improved its operation with higher line throughput at a lower cost.,/p>

Replacing a manual case-palletizing process – an arduous and physically demanding task that required three shifts a day, seven days a week – the customer now has the flexibility to better meet the needs of big retailers that may request quick supply order changes from one type or color of paint to another, reported Packaging Digest in a recent issue.

And then comes NASA. In September 2006, NASA’s Goddard Space Flight Center received R&D magazine’s annual R&D 100 award for developing what it calls “a conformal gripper.” This gripper was originally developed for lunar missions, and because it uses an array of pins that gently conform to any object’s shape, it basically renders obsolete the slew of operation-dedicated grippers that are on the market today.

High tech space-born applications aside, what is really driving developments in automation is one of the rising trends of convenience foods, says Jörg Herrmann, from Germany’s gripper manufacturer Schunk.

Demanding consumer market

“The food and packaging industry is a growing market for us as people increasingly want more flexible packaging containing ready-made foods,” says Herrmann. “And the demographics are clear.

There are more and more single households, which means that people are not buying two kilos of meat. What they buy instead e.g. is a single portion with meat, noodles and a vegetable. So the robots and gripping systems that pick, pack and palletize all this food have to be designed especially for the food industry.

The hygienic design is a big trend for components that have direct contact with food,” says Herrmann. While palletizing and depalletizing is one of the primary tasks of robots in the packaging industry, what is happening more and more, says Volker Schnell from Schmalz, a German company which specializes in vacuum technology, is that customers need the possibility to have mixed pallets.

“The market is asking for more complex handling applications like using robots to palletize different products in different layers under more complex circumstances,” says Schnell. “At the same time there are tremendous advancements in sensor technology, image processing for the gripper controls, and online condition monitoring of the robots and grippers.”

A gripper snapshot
Here’s a look at some innovative grippers and the companies who make them:

Schunk and robomotion

Two Germany-based companies, Schunk, which focuses on development, manufacturing and improvement of production methods, and robot technology specialist robomotion, have jointly developed a special hygienic gripper for the meat industry: the mechanical two-finger Angled Gripper Type LMG 64.

The gripper features a hygienic design that is easy to clean and a payload of 10 kg and a gripping force 350 Newton. The gripper is sealed according to IP69 K standards, and can be used for FDA-approved materials.

PIAB

Sweden-based vacuum and measuring technique specialist PIAB has developed COAX, an advanced solution for creating vacuum with compressed air. COAX cartridges are smaller, more efficient and more reliable than conventional ejectors.

This allows for the design of a flexible, modular vacuum system. COAX technology is ideal for machine integration in a variety of material handling applications for the packaging, automotive and graphic industries.

J.Schmalz

German company Schmalz is another leading company in the area of vacuum handling technology. For the packaging industry, Schmalz has large-area vacuum grippers, the FX/FXC, with an innovative valve concept that is energy efficient even with short cycle times.

The grippers are suitable for use in a range of applications, including automated palletizing, depalletizing, commissioning and sorting of many different types of goods in various sizes with only a single gripper. The gripper also is designed for handling of workpieces made of many different materials, such as cardboard, wood, sheet metal (dry) and plastic, with or without apertures.

Source: http://www.abb.com/cawp/seitp202/44038416ff2d8490c12573310038cab8.aspx