On-orbit identification of time-varying moment of inertia for spacecraft based on a recursive subspace method

In this paper, a novel recursive method to identify the moment of inertia parameters of on-orbit spacecraft is proposed. Different from the frequently-used momentum conservation and least squares approach, the presented method is implemented based on the Projection Approximation Subspace Tracking (PAST), and the moment of inertia parameters can be determined recursively from the system state-space model by coordinate transformation. For a spacecraft with flexible appendages, three on-orbit cases that may cause the moment of inertia parameters to vary with time are investigated. In numerical simulations, comparing with the classical subspace method based on the singular value decomposition (SVD), the results illustrate that the proposed recursive algorithm can identify the time-varying moment of inertia parameters effectively. Moreover, the computational efficiency is also higher than that of the SVD-based method without the decomposition of the Hankel matrix.