Hybrid Vibration Isolation System for Whole-Spacecraft Launch Protection

The proposal describes an active and passive system that will supplement a passive isolation system.The baseline passive isolation system consists of a graphite epoxy/honeycomb core laminate formed into an essentially flat plate. An integral low-bending-stiffness outer band provides the capability to tune the modal frequencies of the system to achievesignificant levels of payload isolation. Constrained layer damping is used to damp at the isolator vertical mode.Further reduction in response is possible if the passive isolation frequency is reduced. However, this is limited by concerns that rocking mode response is too high. Unfortunately, passive vertical stiffness of the diaphragm affects both vertical androcking frequencies.The opportunity here is to use active controls or other passive means to mitigate rocking mode response. Sensors will differentiate between rocking modes and the primary vertical mode. Actuators will be used to independently control either rocking orvertical motion. After rocking motion has been suppressed, the passive system is modified so that the vertical frequency near 30 Hz is lowered without subjecting the payload to increased lateral motion.The active system can also be used to add supplemental isolation in a critical frequency band and to minimize effects of initial loading. Fragile structures may be launched from ICBMs. Also, since increased payload isolation has the potential to save spacecraft structural weight, an active/passive hybrid isolation system may have a competitive advantage over traditional passive isolationsystems.