CIFER(R)를 이용한 무인 헬리콥터의 동특성 분석 (2) -주파수 응답 해석

• Published in: Journal of biosystems engineering 2011-12, Vol.36 (6), p.476
• Main Authors: 배영환, Yeong Hwan Bae, 구영모, Young Mo Koo
• Format: Article
• Language: Korean
• Subjects: CIFER; Flight dynamics; Frequency response; Identification modelling; Unmanned helicopter
• ISSN: 1738-1266

The aerial application using an unmanned helicopter has been already utilized and an attitude controller would be developed to enhance the operational convenience and safety of the operator. For a preliminary study of designing flight controller, a state space model for an RC helicopter would be identified. Frequency sweep flight tests were performed and time history data were acquired in the previous study. In this study, frequency response of the flight test data of a small unmanned helicopter was analyzed by using the CIFER software. The time history flight data consisted of three replications each for collective pitch, aileron, elevator and rudder sweep inputs. A total of 36 frequency responses were obtained for the four control stick inputs and nine outputs including linear velocities and accelerations and angular velocities in 3-axis. The results showed coherence values higher than 0.6 for every primary control inputs and corresponding on-axis outputs for the frequency range from 0.07 to 4 Hz. Also the analysis of conditioned frequency response showed its effectiveness in evaluating cross coupling effects. Based on the results, the dynamic characteristics of the model helicopter can further be analyzed in terms of transfer functions and the undamped natural frequency and damping ratio of each critical mode.