Prototype Moving Base Gravity Gradiometer
Semiannual technical rept. no. 1
HUGHES RESEARCH LABS MALIBU CA
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The report covers the technical studies accomplished during the first six months to design and develop a prototype moving base gravity gradiometer. The scope of work is limited to establishing the instrument and system design parameters during the time period covered by this report. The report presents preliminary designs, and summarizes advantages and disadvantages for three sensor vibration isolation concepts rotating floated spherical sensor, two- axis mechanical gimbal ring sensor mount, and two axis air pad gimbal mount. A summary of tentative sensor parameters is presented. The report presents in detail, a system error budget that indicates errors reflected at the individual sensor output as well as at the individual gradient tensor element. Derivations of sensor error mechanisms are presented. Errors due to rotational field effects, arm mass unbalance and magnetic field interactions are derived. Design concepts and parameters for the various subsystems are presented. Sensor arm mass and inertia balance are discussed as are estimates for the sensor translational and angular vibration environment. The spin bearing performance characteristics, error mechanism and requirements are presented. Lastly, efforts to find and select suitable materials are documented.