AN OPTIMAL DYNAMIC OUTPUT-FEEDBACK CONTROLLER FOR A FLEXIBLE SPACECRAFT

The design of a low‐order dynamic output feedback controller for a flexible spacecraft is carried out using modified linear quadratic Gaussian (LQG) theory. The necessary conditions for optimization are given. The linear equations governing a flexible spacecraft with a central rigid body and two sun‐tracking solar panels are presented. The parameters of the Solar Electric Propulsion Spacecraft (SEPS) are selected for analysis and simulation. The optimal gains for the dynamic controller are estimated using an iterative algorithm. The sequential procedure which assures convergence is selected. The initial gains which stabilize the system are chosen on the basis of the principle of a PD controller. A third‐order controller for pitch, roll and yaw axes of the 18th‐order system, which includes sensor and actuator dynamics, is designed. Numerical simulations carried out to ascertain the performance of the controller show the performance to be satisfactory. Copyright © 1990 John Wiley & Sons, Ltd.