Hardware / software design challenges of low-power sensor nodes for condition monitoring

Summary form only given. Structural Health Monitoring (SHM) is a new challenge in wireless sensor design. In our project we are proposing an ultra-sonic measurement system to find malfunctions within structures. Examples of such structures are aircraft bodies and the wings of a wind turbine. It is required to allow for long term monitoring from a single battery or even using energy scavenging techniques. First of all the measurement algorithms are analyzed. Here we have to find a trade-off between energy consumption of the sensor, required memory size, computational power; duty cycle and timing jitter between actuator and sensors. Most important method to control the energy consumption of the system is an efficient duty cycle control. As most of the time the sensor is sleeping the overall timing of the system has to be maintained and refreshed in a continuous manner. A high timing accuracy results also in higher power consumption during sleep mode, while a low power RC oscillator needs a higher refresh rate. For the wireless system we need to trade-off between power consumption during active mode and data rates. While we are able to transfer more data in a shorter period of time with a high performance system, the overall energy consumption with low data rates could be higher if the on-time of the RF (radio-frequency) frontends is much longer even if the RF-frontends consumes less power in a low data rate mode. In the paper and presentation the use cases and design decision are described based on the outcome of the system analysis.