UAV Propeller Frequency Analysis with LiDAR and Sliding Windows

Student’s name: Zach Crennen Home Institution: Colorado School of Mines NNCI Site: MONT @ Montana State University REU Principal Investigator: Dr. Wataru Nakagawa – Department of Electrical and Computer Engineering, Montana State University REU Mentor: Dr. Bradley Whitaker – Department of Electrical and Computer Engineering, Montana State University Abstract: While extensive research has been conducted on detecting various propeller-bearing objects using different modalities, there is limited work on detecting the frequency and angle of rotating propellers. This study aims to answer the question: "Within what range of tilt angles can the frequencies of a rotating propeller be identified in the spectral analysis of LiDAR pulses on a stationary propeller?" We propose a LiDAR-based solution to detect both frequency and angle via spectral analysis. Using CNN bounding box detection to identify the propeller signal in a spectrogram, we anticipate that frequencies can be detected within a range of 70-90 degrees. We expect our results to indicate that the system's performance is primarily dependent on the angle between the propeller and the LiDAR beam, as well as the position of the beam on the propeller. While we find that frequency detection appears straightforward, identifying the angle of the propeller will likely remain inconclusive.