Study On The Torsional Moment Flexure Hinges Gradiometer Based On Capacitance Transducer

The gravity gradient is the second derivative of the gravity potential, which can reflect the slim change of the geological structure. The gravity gradiometer behaves important applications in the fields of the Earth science, such as inertial navigation, geophysics, earthquake, geology science, Earth's resource survey and so on.The measurements of gravity gradient generally can be divided into two models, differential acceleration measurement and torque measurement model. In this paper, the flexure hinges gravity gradiometer based on the principle of torque measurement combined with a high-precision capacitance transducer is designed, and then one-dimension and two-dimension gravity gradiometer prototypes are, respectively, constructed and experimental investigated. Experimental results show that the two-dimension gravity gradiometer combined with a two-dimension capacitance transducer behaves resolutions of the gradiometer elements WXX-WZZ and WXZ of 47E and 37E respectively, which are limited by the electrical noises of the capacitance transducer.The resolution of the hinge torque gravity gradiometer could be improved by a factor of 9 by reducing the gaps of the capacitance electrode from presented 0.3mm to 0.1mm. In addition, the closed-loop electrostatic torque actuators should be added in order to improve stability and reduce the nonlinear of the flexure hinges.