High Bandwidth Fast Steering Mirror

As the Airborne Laser (ABL) comes closer to directing a high energy laser (HEL) at a boosting missile target, it is essential that higher bandwidth fast steering mirrors (FSMs) need to be developed. These FSMs must be capable of controlling large 12-inch mirrors while handling the HEL power levels. Unfortunately, it is unlikely that a FSM mechanism (substrate and mounting structure) can be designed and built to have structural frequencies high enough to provide a 2 KHz open-loop bandwidth using conventional control algorithms as this would require structural frequencies on the order of 6-10 KHz. Applied Technology Associates proposes to provide the Missile Defense Agency innovative, adaptive mirror control concepts for high bandwidth (2 KHz) fast steering mirrors that can accommodate lower mirror structural frequencies. A Model Reference Adaptive Filter approach is the leading candidate for accomplishing this. In this concept, an ideal plant response is designated the model. Then a real-time adaptive filter is included in the control loop of the plant such that its filtered response matches the model. This technique automatically identifies and compensates for structural resonances, and furthermore can adapt if those characteristics change over time. Alternate advanced control concepts will also be investigated.