Novel Ultrasonic Ranging Approach Based on Spread Spectrum Modulation

Ultrasonic devices are widely used in robotics as exteroceptive sensors for ranging measurements. In previous studies, the combination of ultrasonic technology with spread spectrum (SS) modulation technology has been proved to have a higher performance in comparison with traditional ranging method. However, how to reduce the computational effort effectively whilst increasing the accuracy of measurement and how to improve the robustness of the ultrasonic ranging system are still challenging problems. This paper proposes a novel approach for ultrasonic distance measurement, which is ground on demodulation of 2-level phase shift keying (2PSK) signals by using two-step digital correlation and a new peak detection method by using the symmetrical characteristic of the pulses. The experimental results obtained indicate a significant improvement of the sensor performance.