Characterization and Optimization of Level Measurement by an Ultrasonic Sensor System

The problem of environmental disasters due to oil spills has characterized recent history from the early '900, still being an important risk factor for environmental protection. Aim of this research is designing and implementation of a non-contact ultrasonic sensor system capable of providing the water level in the marine environment. This system is part of a very low-cost device developed to detect water pollution by non-conductive liquids (i.e., hydrocarbons floating in the sea), exploiting the different conductivities of fluids involved. While equipment and techniques currently used for monitoring marine water pollution are very expensive, this paper focuses on the characterization of a low-cost SRF05 ultrasonic sensor and on its implementation inside a floating organ as a result of data obtained from laboratory tests. A number of experimental tests were conducted using a micrometric linear stage, a triangulation laser, a digital oscilloscope, and a post-processing software. Moreover, changes of climatic conditions, such as temperature and humidity, were monitored in a climatic chamber, aiming to establish the best operating range in terms of sensor resolution and the architecture of a buoy. The sensor showed signal anomalies at regular distance intervals due to anticipated flight times, which led to the adoption of a sensor system consisting in the combination of more SRF05 sensors to optimize the measurement system. In addition, it is presented an analytical method based on ultrasonic signal reconstruction, with the aim to improve the accuracy of the measurement method. The final device is managed to have a sensibility of about 1 mm.