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A novel spacecraft architecture, known as Disturbance–Free Payload (DFP), has been presented and successfully demonstrated experimentally. In this architecture, the payload and the spacecraft are separate bodies that fly in close-proximity formation and interact through non-contact sensors and actuators to achieve precision payload control and isolation from spacecraft disturbances. Vibration isolation is provided down to zero frequency and isolation performance is not limited by sensor characteristics. A thorough set of tests has been conducted using a two-dimensional testbed to determine the level of broadband isolation achieved using this concept. Test configuration modifications and hardware upgrades have resulted in an improvement over prior test results. These recently completed tests demonstrate, in the laboratory, measurement of broadband (0.1-100 Hz) isolation of over 64 dB (a factor of 1700). This measurement far exceeds any space-based vibration isolation experiments and would only improve in a quieter background, such as space. I. Introduction ew advancements in the area of vibration isolation for space applications have been few and far between. Demonstrations of new concepts are equally rare. To meet the stringent pointing and control requirements of future space-based systems, developments in the area of vibration isolation need to be made and demonstrations to validate the concepts are necessary to make them flight worthy. A novel concept, known as Disturbance-Free Payload 1 (DFP), was introduced by Pedreiro 2 . This architecture provides unprecedented control and motion stability for space borne systems. An experimental apparatus was built and used to demonstrate the DFP concept in two dimensions (Ref. 3). The experiment emulates a payload and spacecraft which are mechanically decoupled and contains sensors and actuators for real-time control implementation and performance assessment. The testbed was used to demonstrate operational capabilities, such as pointing, vibration isolation, slew, and momentum dump, and to assess performance. Results from initial tests showed isolation performance in excess of 50 dB. However, these preliminary performance assessment results were limited by sensor noise and actuator capability. Improvements to testing procedures and hardware have resulted in measurements of over 64 dB broadband isolation performance (0.1 Hz-100 Hz), which is well beyond the state-ofthe-art. |
