Schunk has developed a special grip for the Fanuc heavy-duty robot M-2000iA with 1200 kg working load.   Photo: Fanuc Robotics

The human is so far the unsurpassed model for robotic grips. Today, however, sensors make the grips highly sensitive, and image processing gives them eyes. But the increasing payloads for robots are also a challenge for grip manufacturers. Grips are the hands of robots and, in many cases, it is only thanks to them that the robots can do their work in the first place. They have to keep up with all the on-going developments in robots, which are having to move increasingly heavy loads. “We are going along with this trend by producing grips in which the relationship between working load and their own mass is optimised,” says Matthias Poguntke, director of product management automation at Schunk GmbH & Co. KG. “The lighter the grip, the heavier the workpiece can be.” Powerful grip handles heavy loads for machine tools The firm, based in Lauffen, has developed an electric grip for the Fanuc heavy duty robot M-2000iA/1200 which can develop a gripping force of around  23 000 N with a travel of 100 mm per finger. In 2009, we were astonished to watch this duo at a machine tool fair, handling alternately a machine bed weighing 700 kg and a bearing ring of 850 mm diameter without need to change the grip cheeks. “The grip system for the Fanuc fair presentation hardly weighed 350 kg,” Poguntke emphasises.

Optimising stiffness of the heavy load grip using the finite element methode

The stiffness of the heavy load grip and its cheeks was optimised with the finite element method so that no unacceptable forces come to bear on any one point. At the same time, superfluous material has been rigorously removed. The electric drive for this special grip is provided via a centrally mounted trapezoidal thread which transfers the force evenly and precisely to the roller-guided base jaws. Operations are guided by the robot’s control system, which treats the grip as a seventh axis.

The intelligence of the grips is increasing

Schunk has correspondingly expanded its auxiliary equipment to include the new changer system SWS-L-1210, specially optimised for use with heavy-duty robots. It has three securing systems as standard and can thus handle static moments in all three axes of 5400 N under a loading of 1200 kg, the firm informs us. For simple mounting on the robot arm, the changer comes ready with pin-holes for the ISO flange with a diameter between 200 and 250 mm.
Grips are also becoming more and more intelligent. “In modern grip systems, sensors have now become standard equipment,” is the Schunk manager’s view. To guarantee process security, the system ascertains via sensors whether the grip is open or closed. In many cases, sensors for component presence or gripping force are put to use.

Robot grip learn to see

“In addition, industrial image processing is opening up many new possiblities,” says Poguntke. “Grips with vision play their most important role where components are come in varying order. ‘Lucky dip’ is one way of describing this handling challenge. “There is a similar problem when components in random order have to be picked up from the belt or when different workpieces have to be handled. With image processing, the grips recognise the goods to be handled and adapt automatically.”

Nature helped to shape the development of Festo’s FinGripper. This adaptive grip has three-dimensional fin-ray structure imitating a fish’s tail fin. The three grip fingers adapt flexibly and elastically to the contour of the workpiece when a lateral force is applied – independent of the components contours. The FinGripper enfolds the workpiece to be held, e.g. a lightbulb, in the same way as a hand, the Esslingen-based firm emphasises.

The finest motor skills amongst the grips are supplied by Festo

For highly sensitive gripping of fragile workpieces, a suitable tool is the Bernoulli suction grip by Festo. It offers a contactless picking-up of, for example, silicon-based wafers by creating overpressure at the Bernoulli grip itself, while underpressure is produced on the surface to be gripped, so that the wafer is picked up by suction.

Bernoulli grips work with overpressure

The workpiece is thus drawn towards the grip until an equilibrium is reached between weight, the back-pressure of air from the jet, and the attractive force from the accelerative impulse of the fluid. This is achieved  when the grip is at a certain distance of around 0.5 to 3 mm from the gripping surface of the component, allowing contactless holding of the object.

Due to nursing staff being scarce and expensive, the Federal Minister for Research is boosting its promotion for developing robots as elderly care nurses. Image: obs/Johanniter Accident Assistance

Emergency-call management systems that call for help on their own, floorings that identify and report hazardous falls or robots bringing breakfast in bed – intelligent assistance systems offer elderly people the opportunity of living at home safely and securely. This is the reason behind the German Federal Ministry for Research and Technology (BMBF) intending to step up the funding for research into “Assistance systems in the service of the elderly” in 2010. In the government bill for the 2010 budget, an increase of 21 million euro to a total of 30 million euro is planned, as reported by the German Federal Ministry for Research. “It is our aim for the elderly to be capable of leading responsible, independent lives for as long as possible”, said Thomas Rachel (MdB), Parliamentary State Secretary in the BMBF in Berlin on Tuesday. The Federal government, he went on to point out, is determined to ramp up research for a self-determined life. Robot research for age-based mobility At the 3rd German AAL (Ambient Assisted Living) Congress jointly organized by the BMBF and VDE in Berlin, Rachel presented a new focus of research promotion: Barrier-free mobility, age-based assistance systems for at home and en route. At the same time, he referred to moot economic, ethical and legal questions – for example, about data protection or liability law. A dialogue involving society as a whole would be needed to discover what kind of technology the elderly really want. To answer these and similar questions, the BMBF will be promoting broadly based social and social science research in the next three years.

Great market opportunities for robots for the elderly

Chairman of the VDE board Dr. Hans Heinz Zimmer pointed to the great market opportunities for products and services of “ambient assisted living”, as this important technological sector is called in Europe.
According to the VDE trend study “Medtech 2020”, Germany is well on the way to becoming global innovation leader in telemedicine and e-health. Zimmer demanded a concept spanning various branches of business and industry for intelligent home networking: “Should we be successful in meaningfully integrating all technical information and communication services, additional potential will be revealed”, said the chairman of the board.