Distance accuracy improvement of FMCW LiDAR using frequency control with a one-shot based frequency detector

Abstract

This dissertation explores the improvement of distance measurement accuracy in Frequency-Modulated Continuous Wave (FMCW) Light Detection and Ranging (LiDAR) systems using innovative frequency measurement and control techniques. The study addresses the limitations of traditional frequency analysis methods, such as Fast Fourier Transform (FFT), in dynamic and noise-prone environments, and proposes the integration of a Frequency-to-Voltage Converter (FVC) and frequency control. The research concentrates on three primary contributions. First, the adoption of an FVC provides real-time frequency conversion, enabling higher resolution at high frequencies compared to FFT. Second, the implementation of frequency control techniques ensures consistent resolution over all frequency bands that FMCW LiDAR aims to measure, overcoming the ripple noise challenges inherent in FVCs. Third, the integration of advanced optical and signal processing methods is demonstrated to enhance system robustness in adverse environmental conditions, such as fog. Experimental results validate the proposed methods, showing a five times improvement in frequency resolution over FFT and a seven-fold improvement over FVC alone in low-frequency scenarios. Furthermore, performance assessments in controlled foggy environments highlight the advantages of longer wavelengths (1550 nm) in maintaining signal integrity compared to shorter wavelengths (650 nm), underscoring the system's adaptability to real-world challenges. This work contributes to the advancement of FMCW LiDAR technology, offering a framework for achieving high-precision distance measurements in diverse applications, including autonomous vehicles, robotics, and industrial automation. The proposed solutions provide a significant step forward in addressing the accuracy, resolution, and environmental resilience of FMCW LiDAR systems. Jubong Lee (이주봉). Distance accuracy improvement of FMCW LiDAR using frequency control with a one-shot based frequency detector (원샷 기반의 주파수 센서 및 주파수 제어를 이 용한 FMCW 라이다의 거리 정확도 향상). Department of Mechanical Engineering. 2025. 76p. Advisor Prof. Kyihwan Park (박기환)