Abstract: For the aero-servo-elasticity issues of near-space high-speed vehicles, a fixed-time control algorithm with adaptive identification and suppression of elastic modes is proposed by integrating multidimensional signal decomposition and adaptive notch filtering algorithms. Firstly, to address the issues of deep coupling between rigid-body and elastic-modal signals in the rate sensor measurements, and the elastic modal identification accuracy and speed caused by low signal-to-noise ratio, a multidimensional ensemble empirical mode decomposition with adaptive noise is applied. This method performs multi-scale decomposition and adaptive modal screening on the measured signals, thereby separating the nonlinear rigid-body motion components from the time-varying elastic modal components. Meanwhile, an improved serial adaptive notch filter is proposed. By introducing a projection operator with hard constraints and an inter-stage cross-correction term into the adaptive update law, this filter effectively suppresses parameter drift and inter-stage error coupling, achieving higher identification accuracy and speed than traditional adaptive notch filters. Then, a deep forest online supervision strategy is proposed. Unlike conventional methods that adopt fixed thresholds to define constraint intervals, this strategy uses the deep forest algorithm to generate a frequency identification envelope with dynamically adjustable constraints in real time, and it corrects the notch filter output online. This ensures that the identification rate of the notch filter is always higher than the decay rate of elastic modal energy. Finally, the identified results are used as the center frequencies of the IIR notch filter, and a robust uniformly convergent observer is introduced to design the fixed-time control algorithm. Simulation results demonstrate that the proposed algorithm can significantly improve the identification accuracy and speed of elastic modes, effectively suppress aero-servo-elastic effects, and achieve higher control precision.

Key words: Near-space high-speed vehicle, Elastic Modal Identification, Serial Adaptive Notch Filter, Empirical Mode Decomposition, Fixed-Time Control