Advanced System Engineering

Wireless Sensor Systems

© Fraunhofer ENAS
RFID design for specific harsh environment applications.
© Fraunhofer ENAS
Far field of smart sensor module.

Modern industrial systems such as conveyor and production systems, wind turbines or aircrafts, are exposed to high loads and an associated wearout. To avoid failures due to unforeseen defects, a continuous sensory monitoring of such components is crucial. In this context, the engaged sensor systems must generate a digital and failure-free output signal that automatically adapts to the input variables of event space and allows an independent signal optimization by the fusion of different input signals (e.g. temperature, power, speed, acceleration, etc.). The parallel detection of several system parameters and the combination of various sensor signals allow the detection and compensation of defective sensors or faulty information in situ. At the same time, the sensor data should be measured directly on the manufactured work piece or critical moving parts (drives, blades of wind turbines). This limits the use of classically wired sensor systems largely. To overcome the limitations, small sensors that permanently monitor their surroundings and transmit observed data wirelessly form the core of such systems. These sensors usually require a processor, some memory and a wireless sending and receiving unit for the assessment and the transmission.

In order to allow a sensor to run autarkic it needs an integrated energy supply. Most easily a battery can be applied. However, for employing sensors without a time limitation and without the need of maintenance, an energy-harvesting concept that uses external energy from sources as sunlight, warmth, vibrations, movement or even a wireless energy supply has to be implemented. Especially in the field of energy supply of such systems the ASE has many years of experience in the development and deployment of intelligent RFID systems and the inductive energy transfer under harsh industrial conditions collected in a large number of funded and industrial projects. This knowledge base on highly efficient modeling and analysis methods for the characterization of high frequency electromagnetic systems, takes hard EMC conditions among others into account. Our department is researching the realization and integration of complete sensor systems that incorporate existing methodologies and technologies from the fields of sensor technology, wireless data and energy transmission, as well as energy harvesting. The highest demands are made regarding complete systems in respect to energy efficiency, flexibility and overall size. They are also required to be multifunctional and cost-effective. In order to be able to efficiently dimension, optimize and read a new sensor, it is necessary to adapt or re-design the assessing electronics, the energy supply and the transmission of data for every individual application situation. Therefore it is the goal of the research and development conducted by the department ASE to provide innovative, customer-orientated solutions for the optimization of existing methods and techniques.