Jinseok Jeong

This study proposes a frequency-domain diagnostic approach for detecting and characterizing unmanned aerial vehicle (UAV) propeller damage using only motor electrical signals. Motor current signals were analyzed via fast Fourier transform (FFT) across 36 systematically defined damage scenarios covering multiple locations and severity levels. The results demonstrate that specific harmonic components of the DC-link current exhibit strong and consistent sensitivity to propeller damage, with the sixth harmonic showing the most pronounced deviation from the normal state. Quantitative analysis revealed clear location-dependent trends: leading-edge damage produced frequency standard deviations up to 93.5 Hz, approximately 2.26 times higher than trailing-edge damage, while tip damage caused progressive bandwidth expansion, reaching 322.07 Hz, the largest variability observed. In contrast, hub-proximal damage exhibited minimal deviation, with bandwidths as low as 108.7 Hz. These findings confirm that motor current signals alone enable reliable discrimination of propeller damage presence, type, and coarse location, providing a practical and scalable solution for sensor less UAV ground inspection and maintenance.

The use of unmanned aerial vehicle (UAV) applications has grown rapidly over the past decade with the introduction of low-cost microelectromechanical system (MEMS)-based sensors that measure angular velocity, gravity, and magnetic field, which are important for an object orientation determination. However, the use of low-cost sensors has also been limited because their readings are easily distorted by unwanted internal and/or external noise signals such as environmental magnetic disturbance, which lead to errors in attitude and heading estimation results. In an extended Kalman filter (EKF) process, this study proposes a method for mitigating the effect of magnetic disturbance on attitude determination by using a double quaternion parameters for representation of orientation states, which decouples the magnetometer from attitude computation. Additionally, an online measurement error covariance matrix tuning system was implemented to reject the impact of magnetic disturbance on the heading estimation. Simulation and experimental tests were conducted to verify the performance of the proposed methods in resolving the magnetic noise effect on attitude and heading. The results showed that the proposed method performed better than complimentary, gradient descent, and single quaternion-based EKF.

본 논문은 고온 환경의 화력발전소 보일러 내부 점검용 드론 개발을 위한 선행연구로 AirSim을 이용한 고온 환경에서의 시뮬레이션을 통해 드론이 정상적인 비행이 가능한지 검증 하였다. 고온의 비행 환경에서는 공기 밀도, 점성계수 등이 상온과 달라 공력특성이 달라지며 이에 따라 드론의 비행성능 또한 달라진다. 따라서 온도 변화에 따른 프로펠러의 공력 특성의 변화를 확인하기 위해 JBLADE를 통한 프로펠러 해석과 추력 테스트, 전기추진계통 성능예측모델을 통한 동작특성 예측을 수행하였다. 그리고 해석 및 성능예측 결과를 AirSim에 적용해 시뮬레이션을 진행하고 결과 분석을 통해 기체 재설계를 진행하였다. 재설계 결과 80°C의 환경에서 호버링 시 필요한 추력을 얻기 위해 재설계 전 최대 출력의 약 65% 사용하던 것이 52%로 감소함을 확인하였다.

In this study, an improved model of the electric propulsion system is proposed in order to analyze the performance of large-size multicopter unmanned aerial vehicles. The main improvement of the proposed model is to reflect the armature reaction of the motor, which effectively explains the significant performance degradation in high-power operation. The armature reaction is a phenomenon, in which the main field flux is interfered by a magnetic flux and, as the size and output of the motor increase, the effect of armature reaction also rapidly increases. Therefore, the armature reaction must be considered for the optimal design and performance analysis of large-size multicopter platforms. The model proposed in this study includes several mathematical models for propellers, motors, electric speed controllers, and batteries, which are key components of the electric propulsion system, and they can calculate key performance data, such as thrust and torque and power consumption, according to given product specifications and input conditions. However, estimates of the armature reaction constants and heat profiles of motors need to be obtained in advance through experimental methods, since there is not yet enough data available in order to derive an estimation model. In conclusion, a comparison with the static thrust test of some commercial products confirmed that the proposed model could predict performance in the high-power operation of electric propulsion systems for large multicopter platforms, although some errors were noted.

Since unmanned aerial vehicle (UAV) for industries are operated in complex low altitude environments, planning feasible paths is a necessary feature to achieve mission goals. D* Lite is applicable for industrial complex that uncertainties exist. This paper focuses on 3D path planning for quadcopter UAV based on D* Lite. Simulation results show that the algorithm can be applied in cluttered static and dynamic environments including unknown obstacles. In addition, when some waypoints exist, the proposed algorithm is able to optimize the global path by determining visit order. Therefore, this study is expected to contribute to increase the application of UAVs in industrial fields.

HILS(Hardware In the Loop Simulation)를 이용한 소형 무인항공기 개발은 비용과 시간을 줄이면서 무인항공기의 신뢰성을 높이는데 효과적으로 사용될 수 있다. 또한, 실제 비행 중에 발생할 수 있는 비행제어컴퓨터의 사용 불능상태 등을 고려한 시뮬레이션을 개발과정에 반영하면, 인명 및 재산상 피해 등의 위험을 감소시킬 수 있다. 이러한 HILS를 적용하기 위해서는 실제 비행 조건과 유사한 환경을 제공할 수 있는 실시간 시뮬레이션 환경이 요구된다. 따라서 본 논문에서는 6자유도 모션테이블을 이용하여 소형 무인항공기용 실시간 HILS 환경을 구축하였다. 선행연구에서 개발된 6자유도 모션테이블을 실시간으로 HILS 환경과 연동하기 위하여, 동작 알고리즘을 위치제어 방식에서 속도제어 방식으로 변경하여 설계 하였다. 또한, 모션테이블의 실시간 동작을 확인하기 위해 역기구학 및 동작 시뮬레이션 모델을 Matlab Simulink®에서 모델링하고 검증하였다.

Study on Production of Power Monitoring Unit for Electric Propulsion UAV Electric Propulsion Unmanned Aerial Vehicle;Lithium Polymer Battery;Power Monitoring Unit;Battery Management System;State of Charge;Flight Control Computer;Flight Data Recorder; This paper describes the design and implementation of previously developed PMU (Power Monitoring Unit) for LiPB (Lithium-ion Polymer Battery) that is electric propulsion used as unmanned aerial vehicle's power source. Improved PMU provides stable voltage and current to various sensors and elctric motors necessary during flight. Voltage and current monitoring function that is measured by improved PMU more precisely be enhanced and the monitoring channel and temperature sensor is added. To verify the improved performance of the equipment, it is integrated to electric propulsion system of unmanned aerial vehicle. PMU is calibrated through the ground test. And PMU's performance is checked through the flight test.