idw – Informationsdienst Wissenschaft
Nachrichten, Termine, Experten
Nachrichten, Termine, Experten
idw - Informationsdienst
Wissenschaft
Energy remains a significant factor in industrial production processes. High levels of energy consumption make production more expensive and exacerbate the climate crisis. A new type of robot technology that needs 90% less electricity than conventional systems is currently being developed in Saarland. The technology uses lightweight, shape memory materials to construct novel, non-pneumatic, industrial gripper systems that function without the need for additional sensors. The research team led by Professors Stefan Seelecke and Paul Motzki from Saarland University will be showcasing the technology at this year’s Hannover Messe.
Hannover Messe, 31 March to 4 April, Hall 2, Saarland-Stand B10.
Robot arms are in use in countless modern industrial production settings. They are used for a whole range of tasks, such as holding workpieces in position, inserting components, assembling printed circuit boards, as well as moving, loading or unloading parts. And when they are in use, most of them consume energy non-stop. Taken together, these industrial robot arms consume multiple gigawatts of electrical power. Many of the gripper systems work pneumatically with compressed air, which can be unpleasantly loud. They are often heavy, their moving parts wear out over time, and they tend to execute a constant, highly repetitive motion pattern. This existing technology sets limits on the extent of miniaturization that can be achieved, and small-scale grippers systems with small grip points are particularly hard to realize. Conventional robot arms are also hard to reprogram quickly, and it's often unsafe for human workers to interact closely with them on production lines.
But a new type of drive technology may well make the industrial robots of the future lighter, compacter, more flexible and more energy efficient. The technology is based on lightweight shape memory alloys (SMAs), which the team of engineers led by Professors Paul Motzki and Stefan Seelecke at Saarland University and the Saarbrücken Center for Mechatronics and Automation Technology (ZeMA) are using to build novel robotic grippers. ‘The work we’re doing can help bring about a significant reduction in energy consumption, reducing production costs as well as helping to protect the climate,’ explains Paul Motzki, Professor of Smart Material Systems for Innovative Production at Saarland University and Scientific Director/CEO at ZeMA gGmbH.
The research team will be at this year’s Hannover Messe where they will be showcasing a number of prototypes, including vacuum gripper and jaw gripper systems that can safely hold and manipulate workpieces without requiring the continuous supply of energy. ‘We can control these gripper systems in real time and whenever needed; all we need to do is apply a short pulse of electric current,’ explains Prof. Motzki.
The Saarbrücken gripper system is fully electric and is composed of bundles of ultrafine wires made from nickel-titanium shape memory alloy. These bundles of ultrafine wires act not only as powerful muscles, but as nerve fibres as well. The behaviour of these wire bundles is due to a special property of nickel-titanium alloy, namely that it can switch between two different crystal lattice structures. If an electric current flows through a wire made from nickel-titanium, the material heats up, causing it to adopt a different crystal structure with the result that the wire becomes shorter. When the current is switched off, the wire cools down and returns to its earlier crystal lattice structure and its original length. The material appears to 'remember' its original shape and to return to it after being deformed – hence the name ‘shape memory’ alloy. The wires are therefore able to exert remarkably large forces for their size and can be made to trigger tiny, controlled motions in whatever smart technology the engineers have attached to these minute artificial muscles.
Paul Motzki explains the muscle power of these tiny wire bundles as follows: ‘Nickel-titanium SMA has the highest energy density of all known drive mechanisms, so by using this material, we’re able to exert a substantial tensile force in very small spaces.’ A wire with a thickness of only half a millimetre can exert a pull of some 100 newtons, which is roughly the force exerted by 10 kg. But the researchers use bundles of much thinner, ultrafine wires, as more wires mean a greater surface area and therefore faster cooling rates. This means that the wire ‘muscles’ can deliver rapid, high frequency motions and a stable tensile force. The engineering team in Saarbrücken actually hold a world record in this area: Using a bundle of 20 ultrafine wires, each with a diameter of only 0.025 mm, they can exert 5 newtons of force at a frequency of 200 hertz (i.e. 200 cycles per second). In some applications, the size of the force delivered is most important, in others it is the frequency with which the force is applied. Using the knowledge acquired from several years of research, Motzki’s team is able to tailor the composition of the wire bundles in terms of wire thickness and number of wires per bundle to meet the requirements of specific applications.
Using innovative control and design strategies, the engineers are developing drives that use SMA wires to create lightweight, manoeuvrable and cleanroom-compatible industrial robots. The technology is under continuous refinement in research and PhD projects, which has enabled the Saarbrücken researchers to develop elastic gripper systems with highly flexible ‘fingers’ that can quickly adapt to changes in the shape of a workpiece.
Conventional grippers usually rely on feedback from sensors, but the technology developed in Saarbrücken is self-sensing – the sensor properties are already built into the system. The system is controlled by a semiconductor chip. ‘The shape memory wires effectively act as fully integrated sensors providing us with all the necessary data. An AI system precisely correlates the electrical resistance data with a particular deformation of the wires. As a result, the system always knows the exact position of each bundle of shape memory wires. The data-trained neural networks are able to calculate positional information efficiently and accurately even in the face of disruptive influences,’ explains Paul Motzki. The engineers can therefore program the system to perform highly precise movements. By specifying the electrical resistance values, they can control the wires as needed. ‘Unlike the standard industrial robots in use today, reprogramming is quick and easy with our system and can even be done on the fly when necessary. The gripper can adapt to the geometry of different workpieces while operating,’ says Motzki.
The prototype jaw gripper developed for industrial applications moves both quickly and with pinpoint accuracy. The gripper holds the workpiece securely in a pincer-like grip so that a robot arm handling system can then manoeuvre the workpiece to its desired destination. The prototype being exhibited at this year’s Hannover Messe can exert a force of four newtons, but the technology is scalable in terms of size, jaw stroke and force. The self-sensing properties of SMA wires enable the precise position and condition of the grippers to be monitored without any additional external sensors. And the grippers are able to hold the workpiece in position without requiring energy to be supplied. Depending on the gripping application, the Saarbrücken technology can achieve energy savings of over 90% relative to the conventional pneumatic grippers in use today.
Another prototype being shown by the research team at Hannover Messe 2025 is a vacuum gripper that has flexible gripper fingers with vacuum suction cups located on the fingertips. Here, too, a short electric pulse is all that is needed to generate and later release a load-bearing vacuum. The vacuum gripper mechanism is achieved by arranging bundles of ultrathin SMA wires into a circular muscle around a thin metal disc that can be made to flip up or down, like a frog clicker toy. Applying an electrical pulse makes the wires in the ‘muscle’ contract and the disc flips its position, pulling on a rubber membrane that creates a vacuum if the gripper fingertips are in contact with a surface. Once again, no electricity is needed in order to hold the workpiece in place, even if the gripper is holding a heavy object at an angle over an extended period. ‘And the self-sensing functionality means that our system has integrated condition monitoring, so the gripper knows if the vacuum created is enough to support the load’ says Motzki.
While at Hannover Messe, the research team will also be looking for partners with whom they can develop their technology for new applications.
Background
The research team headed by Stefan Seelecke and Paul Motzki uses shape memory technology for a wide range of applications that include innovative cooling systems, robot grippers and innovative valves and pumps. The technology continues to be developed by graduate students and post-graduates conducting research as part of their doctoral dissertation projects. The team’s results have been communicated extensively in scientific conferences as well as in high-impact journals, with numerous papers receiving international recognition. The research work has also received support from numerous sources, including the multinational engineering and technology company Bosch and from the Saarland state government, which has provided funding through the ERDF projects ‘iProGro’ and 'iSMAT'.
The team also wants to develop the results of its applied research for commercial and industrial applications, which is why the company ‘mateligent GmbH’ was spun off from Professor Seelecke's and Professor Motzki’s department. The company will also be exhibiting at the Saarland stand at the Hannover Messe. (Hall 2, Saarland stand B10)
ZeMA – Center for Mechatronics and Automation Technology in Saarbrücken is a research hub for collaborative projects involving researchers from Saarland University, Saarland University of Applied Sciences (htw saar) and industrial partners. Since its foundation in 2009, ZeMA has focused on industrially relevant development work aimed at transferring ideas and technology from academic research to the industrial sector.
Prof. Dr.-Ing. Paul Motzki:
Tel.: +49 681 85787-13; Email: paul.motzki@uni-saarland.de
https://imsl.de/smartgrip – Learn more about the smart robot gripper systems
https://imsl.de – Intelligent Material Systems Lab
https://smip.science – Chair of Smart Material Systems for Innovative Production
https://imsl.de/projekte – Information and videos on research projects
https://zema.de – Center for Mechatronics and Automation Technology (ZeMA)
PhD research student Tom Gorges (l.) and Master’s student Philipp Göddel (r.) are part of the team d ...
Credit: Oliver Dietze
Saarland University
Professor Paul Motzki (photo) and his research team are presenting prototypes of their robot gripper ...
Credit: Oliver Dietze
Saarland University
Merkmale dieser Pressemitteilung:
Journalisten, Wirtschaftsvertreter, Wissenschaftler
Elektrotechnik, Energie, Informationstechnik, Maschinenbau, Werkstoffwissenschaften
überregional
Forschungs- / Wissenstransfer, Forschungsergebnisse
Englisch
Sie können Suchbegriffe mit und, oder und / oder nicht verknüpfen, z. B. Philo nicht logie.
Verknüpfungen können Sie mit Klammern voneinander trennen, z. B. (Philo nicht logie) oder (Psycho und logie).
Zusammenhängende Worte werden als Wortgruppe gesucht, wenn Sie sie in Anführungsstriche setzen, z. B. „Bundesrepublik Deutschland“.
Die Erweiterte Suche können Sie auch nutzen, ohne Suchbegriffe einzugeben. Sie orientiert sich dann an den Kriterien, die Sie ausgewählt haben (z. B. nach dem Land oder dem Sachgebiet).
Haben Sie in einer Kategorie kein Kriterium ausgewählt, wird die gesamte Kategorie durchsucht (z.B. alle Sachgebiete oder alle Länder).
