Three steps to alleviate control and observation spillover problems of large space structures

"Control spillover" and "observation spillover" have surfaced as major roadblocks to successful application of state-of-the-art control techniques to vibration control of large space structures. Nevertheless, control (observation) spillover may be prevented by proper placement of actuators (sensors). If proper placement is not possible because of structural constraints, control spillover to (observation spillover from) secondary modes can still be prevented by synthesizing the existent actuator (sensor) influences. Alternatively, control spillover to (observation spillover from) nonprimary modes can be reduced, to various extent, by adding some bandstop filter to each input (output) channel. A combined systematic use of placement, synthesis, and filtering will yield better results. This paper presents the underlying theoretical foundation of a proposed three-step approach for alleviating the spillover problems, along with conditions and techniques for proper placement, proper synthesis, and proper filtering. An illustrative numerical example is also included.