Non-crosstalk real-time ultrasonic range system with optimized chaotic pulse position-width modulation excitation

Abstract

Ultrasonic crosstalk is one of the main causes of false distance measurements that reduce the work efficiency of sonar sensors in mobile robots. To enhance the real-time performance of sonar systems, chaotic pulse position-width modulation (CPPWM) sequences are proposed to construct short digital transmission sequences to trigger ultrasonic transducers. Thanks to their properties of sharp autocorrelation and flat cross-correlation, chaotic series are used to modulate both pulse position and width. To obtain the better echo correlation properties and the larger echo energy, the Non-dominated Sorting Genetic Algorithm-II (NSGA-II) is adopted to optimize the pulse periods and pulse duty ratio. Real experiments using Polaroid 600 series instrument-grade electrostatic transducers validate the suitability of the proposed method.