ON-ORBIT IDENTIFICATION AND VIBRATION CONTROL FOR SOLAR ARRAYS WITH LOW AND CLOSE FREQUENCIES

Solar arrays are typical flexible space structure with low and closely spaced natural frequencies and light damping. In this paper, a method of vibration control based on dynamic parameter identification is established to suppress vibrations of space structures. The dynamic parameters are identified by Eigensystem Realization Algorithm (ERA) or its extentions such as ERA/DC and OKID algorithm. Then they are used to design the optimal controller for suppressing vibrations. In light of the requirements and the applicability of the identifying methods and the control laws, three integrated on-orbit identification and vibration control schemes, i.e. LQR, LQG integrated with ERA(ERA/DC) and LQG integrated with OKID, are proposed. Numerical simulations show that the dynamic parameters of a flexible spacecraft with low and closely spaced frequencies can be obtained in a short time with a high precision by using the ERA, ERA/DC or OKID algorithm, and both the optimal control laws LQR and LQG based on the identifying parameter model are very effective for suppressing vibrations of flexible solar arrays. Therefore, it can be tentatively concluded that the identification and vibration control integrated schemes are the appropriate method for on-orbit applications.