Ultrasound in vehicle system for on-board monitoring

摘要

Different types of technological devices have been proposed for indoor positioning but most are hindered by various kinds of interference, due to sources of light or heat in the environment. These might include infrared radiation and artificial vision, as well as radio-frequency, which often need specialized electronic circuitry in order to function properly, hi restricted spaces (e.g. aboard vehicles), monitoring can be performed at low cost with small, reliable devices. These can be relatively simple electronic circuits, which implement various algorithms in order to obtain precise effective signal processing through the use of ultrasound waves. Ultrasound waves in air are affected much less than other forms of radiant energy; they are also efficient under different environmental conditions, besides being compatible with light, temperature variations, and electromagnetic fields. In particular they are very suitable for in-vehicle monitoring. This article treats the development of an ultrasonic sensor based on ferroelectric polymer technology which possesses all of the forementioned characteristics. A network of four transmitter/receiver elements is set up on-board a vehicle and is driven in the frequency range between 30kHz and 120kHz. Results on inside positioning are given by implementing cross-correlation algorithms and finally discussed.