Made-to-measure sensors

Fraunhofer FHR conducts research into innovative sensors which are instrumental in achieving »zero-fault production«. Apart from in-line capability and reliability, the price also plays an essential role in the development phase.

Is there at least one almond in each piece of chocolate? Does the material have the required thickness? Is the product contaminated? All of these questions can be answered with one sensor: radar.

Fraunhofer FHR has been investigating all aspects of radar technology since it was established 1957 and is now one of the leading research institutes in Europe in this area. Sensors for production and industrial applications have already been a focus of the institute's scientific work for many years. In most cases, the requirements are so specific that existing commercial solutions quickly show their limitations. The environmental conditions in the production facilities are also often too harsh for other sensors. Heat, smoke and steam have no effect on radar. It is also not affected by light or darkness. The application spectrum ranges from distance measurement in a steel plant to the detection of contaminants in foods. Other applications include the determination of the degree of ripeness of fruit and the sorting of recycling waste according to type.

The threshold of sensor technology

When developing customer-specific solutions, the price and short development periods are important, but so too are the reliability and durability of the system. Prior to commencing with the design of a new system, the scientists first examine the framework conditions: What type of system is needed exactly? What is the task of the sensor? What is the minimum measurement speed? Which resolution is required? Where should it be installed? Which environmental conditions prevail? Which interfaces need to be realized? What are the maximum system costs? Fraunhofer is dedicated to conducting cost-effective research with a view to creating practical applications and value-added for its partners. Elegant and sophisticated solutions are not an issue here, but rather the provision of the best solution in line with the customer's individual requirements.

After a period of just two to four weeks, the scientists can say, in principle, whether or not something will work. A concrete feasibility study, on the other hand, can last three to six months depending on the level of detail. If required, the scientists will also design the system and build a prototype. On average, this can take up to 24 months. And it goes without saying that they will also support the customer when he is integrating a test system in his production plant. Everything is therefore supplied from one source – from the idea to the pilot series. With short innovation cycles, the scientists can guarantee that the technology is always state-of-the-art. This helps the company to strengthen its market position.

The Fraunhofer FHR test laboratory boasts an extensive range of equipment. Experimental setups for various scan concepts can screen, test and characterize material samples from 100 megahertz up to 300 gigahertz. If required, this can also be carried out on a conveyor line at a belt speed of up to one meter per second. Furthermore, a terahertz spectrometer (up to 2 terahertz) and additional radar sensors are also available. The circuit design and the electromagnetic comparability of the components are verified within the framework of complex simulations.

One chip, one radar

To further extend its portfolio, Fraunhofer FHR has developed competence in the area of chip design. The team develops cost-effective high-frequency circuits that are suitable for the mass market on the basis of silicon-germanium. When produced in large quantities, radar-on-chip systems are very inexpensive. Systems are, however, also being developed for small quantities. The special feature: circuits up to 100 gigahertz and more are implemented in PCB technology (Planar Circuit Board). This reduces costs, paves the way for a compact design and also facilitates construction in line with the customer's specific requirements.

Being a member of various groups and alliances, Fraunhofer FHR has access to wide-ranging know-how, particularly in the area of machine vision. Thanks to the strong network that has been established both within and outside of the Fraunhofer-Gesellschaft, Fraunhofer FHR can always find the optimal consortium. The researchers always come up with a tailored solution, even within the framework of complex projects. They use modular components which are adapted to the respective task in research projects, e.g. through a new system concept, antenna design or special algorithms. The sensors are, as it were, made to measure. Fraunhofer FHR has »basic systems« in different frequency ranges (30, 60 and 90 gigahertz). A 120-gigahertz line-scan camera currently under construction will bring the scientists one step closer to their goal: the development of an imaging, real time and in-line capable sensor.

Hence, Fraunhofer FHR follows the tradition of the scientist and entrepreneur after whom the Fraunhofer-Gesellschaft was named: in addition to developing better ways of doing things, Joseph von Fraunhofer also strived to lower the costs.