Self powered health monitoring

The development of autonomous wireless sensors and actuators in order to design advanced structural health monitoring (SHM) systems is an exciting challenge for both the industrial and the academic communities. Almost all the today's studies about the so-called autonomous systems still require power supply. It means that a fully self-powered system has not achieved yet. For the vibration suppression method, the piezoelement is often located on the vibrating structure as a sensor, then, connected to computer, filter, amplifier, and so on with wires. The vibration supression signal is sent to the actuator which is also located on the structure [1,2]. The Synchronized Switch Damping (SSD) technique which has been originally developed in our laboratory does not require any external electrical devices neither wires but just by putting piezo element connected to a simple electrical devices on the structure, vibration can be well suppressed [3,4,5]. The whole system including electrical circuit is quite small in size and weight, consequently does not purtube the modal structure. Based on the present technique, electrical energy is harvested directly from mechanical energy, vibration, which can be used for other utilities such as the health monitoring. This is called as the Synchronized Switch Harvesting (SSH) system [6,7]. When enough energy is harvested, Lamb wave health monitoring is performed. The entire process was carried out with 300 mm length composite beam. Experimental results show that the required energy to wake up the micro-controller in the electrical circuit, launch the Lamb wave and RF code, is only 1.5 mJ. It shows that required energy can be collected in a short time period so it means that the self-powered health monitoring is feasible.