Abstract: In response to the demand for the in-orbit autonomous operation of ultra-high agility, stability, and precision(ASP) spacecraft, this paper proposes a fully autonomous high-precision in-orbit identification method for structural modal parameters. This approach is designed to overcome the limitations of traditional ground-based processing methods which suffer from poor real-time performance and require significant manual intervention. The proposed method utilizes actuator frequency sweep data and employs a Savitzky-Golay filter to denoise the frequency response data, which significantly suppresses high-frequency noise while preserving key peak features. A novel peak detection algorithm, based on the velocity of motion in the complex plane, is introduced to identify insignificant modes. Subsequently, admittance circle fitting theory is used to calculate the frequency, damping ratio, and gain of each mode. The accuracy of the parameter estimation is comprehensively improved through a segmented frequency band least-squares optimization method. Numerical simulations demonstrate that the proposed method can accurately extract modal parameters even in the presence of noise and disturbances, and the optimized frequency response curve shows a high degree of consistency with the theoretical model. The method's efficacy in a realistic noise environment is validated through a physical experiment, which successfully identifies the resonance peaks of insignificant modes. The resulting identified structural transfer function aligns well with the measured data, providing critical technical support for the high-performance autonomous control of ASP spacecraft.

Key words: autonomous parameter identification, ultra-high agility, stability, and precision spacecraft, modal parameter identification and optimization, admittance circle, Savitzky-Golay filter