IMPULSIVE THRUSTER BASED ATTITUDE STABILITY ANALYSIS OF SPACECRAFT WITH FLEXIBLE SOLAR ARRAYS

Stability analysis is an important tool in determining the robustness of the control system design for spacecraft missions. However, many spacecraft exhibit flexible dynamics due to solar arrays or other appended bodies. Therefore, the stability analysis needs to incorporate flexing behavior in the equations of motion. This paper outlines a method for analyzing the stability of spacecraft with flexing solar arrays using classical linear stability analysis techniques such as Bode plots and gain and phase margins. In order to use classical methods for stability analysis, the nonlinear equations that describe the dynamics of spacecraft with flexing solar arrays first need to be linearized. Another aspect to this problem is the equations of motion for the flexing and spacecraft rotation are coupled through second order state variables. This requires the system mass matrix to be inverted to fit the classical state space form. Finally, an eigenvalue diagonalization on the dynamics matrix is necessary to analyze the transfer functions for the stability analysis tools to show the impact of flexing on the performance. This paper summarizes the methods used for the stability analysis and compares the analytical results to numerical results found by simulating a flexible spacecraft using the Basilisk astrodynamics software package. Additionally, the results are compared to rigid body stability analysis results which shows the key influence of flexing on the robustness of the control design.