Improvement of measurement distance in multi-channel ultrasonic ranging systems through adaptive chaotic pulse position width modulation excitation sequences

In order to enhance the maximum measurement distance of ultrasonic ranging systems, this paper proposes the use of adaptive chaotic pulse position width modulation (ACPPWM) sequences to excite the ultrasonic sensors. The ACPPWM excitation sequence can take full advantage of the bandwidth resources of ultrasonic ranging systems. To increase the ability to suppress crosstalk in a multi-channel ultrasonic ranging system, a genetic algorithm (GA) is used to optimise the ACPPWM sequences. Experiments were carried out using an eight-channel ultrasonic ranging system that consisted of SensComp 600 series instrument-grade sensors. The experimental findings show that the proposed ACPPWM excitation sequence has a better spectral match with the ultrasonic ranging system than the chaotic pulse position width modulation (CPPWM) sequence. With 2 ms optimised ACPPWM excitation sequences, the maximum measured error was 6 cm and the longest measurable distance was 760 cm, with an increase of 11.7% over the CPPWM measurement.