Abstract: A force rebalance accelerometer includes a proof mass suspended by one or more flexures between stationary mounted upper and lower excitation rings. Pick-off capacitance plates formed on opposing sides of the proof mass form capacitance elements whose capacitance varies in response to displacement of the proof mass to provide a displacement signal. The displacement signal is applied to one or more electromagnets, used to force the proof mass back to a null or at-rest position. The drive current applied to the electromagnets thus represents the force or acceleration applied to the accelerometer. The electromagnets include a magnet and a pole piece which forms a magnetic return path. In order to relieve stresses due to thermal expansion, the magnet is spaced apart from the pole piece to enable the bonding area to be constrained to a minimum which, in turn, reduces the overall stress on the accelerometer.

Abstract: An accelerometer is of the type in which a paddle is suspended from a support so that the paddle is displaceable with respect to the support. A suspension arrangement for the paddle includes a pair of compliant beams having longitudinal axes that are substantially orthogonal to each other so that the beams provide compliant isolation to internal stresses while being rigid to external loading forces.

Abstract: A force rebalance accelerometer includes a proof mass suspended by one or more flexures between stationary mounted upper and lower excitation rings. Pick-off capacitance plates formed on opposing sides of the proof mass form capacitance elements whose capacitance varies in response to displacement of the proof mass to provide a displacement signal. The displacement signal is applied to one or more electromagnets, used to force the proof mass back to a null or at-rest position. The drive current applied to the electromagnets thus represents the force or acceleration applied to the accelerometer. The electromagnets include a magnet and a pole piece which forms a magnetic return path. In order to relieve stresses due to thermal expansion, the magnet is spaced apart from the pole piece to enable the bonding area to be constrained to a minimum which, in turn, reduces the overall stress on the accelerometer.

Abstract: A force rebalance accelerometer includes a proof mass suspended by one or more flexures between stationary mounted upper and lower excitation rings. Pick-off capacitance plates formed on opposing sides of the proof mass form capacitance elements whose capacitance varies in response to displacement of the proof mass to provide a displacement signal. The displacement signal is applied to one or more electromagnets, used to force the proof mass back to a null or at-rest position. The drive current applied to the electromagnets thus represents the force or acceleration applied to the accelerometer. The electromagnets include a magnet and a pole piece which forms a magnetic return path. In order to relieve stresses due to thermal expansion, the magnet is spaced apart from the pole piece to enable the bonding area to be constrained to a minimum which, in turn, reduces the overall stress on the accelerometer.

Abstract: A force rebalance accelerometer includes a proof mass suspended by one or more flexures between stationary mounted upper and lower excitation rings. Pick-off capacitance plates formed on opposing sides of the proof mass form capacitance elements whose capacitance varies in response to displacement of the proof mass to provide a displacement signal. The displacement signal is applied to one or more electromagnets, used to force the proof mass back to a null or at-rest position. The drive current applied to the electromagnets thus represents the force or acceleration applied to the accelerometer. The electromagnets include a magnet and a pole piece which forms a magnetic return path. In order to relieve stresses due to thermal expansion, the magnet is spaced apart from the pole piece to enable the bonding area to be constrained to a minimum which, in turn, reduces the overall stress on the accelerometer.

Abstract: A force rebalance accelerometer includes a proof mass suspended by one or more flexures between stationary mounted upper and lower excitation rings. Pick-off capacitance plates formed on opposing sides of the proof mass are used to form upper and lower capacitance elements whose capacitance varies in response to displacement of the proof mass to provide a displacement signal. The displacement signal is applied to one or more electromagnets which are used to force the proof mass back to a null or at-rest position. The drive current applied to the electromagnets thus represents the force or acceleration applied to the accelerometer. The electromagnets include a magnet, rigidly secured to an excitation ring which forms a magnetic return path. A flux control groove is formed in the excitation ring to reduce leakage flux and flux concentration which would otherwise result in the magnetic return path at the magnet interface.

Abstract: A combined transducer that measures force or displacement and temperature utilizes a pair of vibrating tines to provide a simultaneous output representative of temperature and force or displacement whereby the sum or average of the vibrating frequencies of the two tines is representative of temperature and the difference is representative of force or displacement.

Abstract: An improved technique for mounting a coil to a paddle in a force rebalance accelerometer so as to provide relief from temperature induced strains without increasing the mass of the proof mass. The coil is mounted to the paddle at a plurality of mounting sites on the paddle, at least one of which is connected to the paddle by suspension means compliant for movement in the plane of the paddle. In a preferred arrangement, three mounting sites are used, two of which are moveable towards and away from the third, fixed mounting site.

Abstract: Prior detection circuits for measuring capacitance differences have commonly included error source, such as P-N junctions, in the DC signal path. The present invention provides an improved detection circuit for measuring the capacitance difference between first (C.sub.1) and second (C.sub.2) capacitive elements. The detection circuit comprises a first capacitor (C.sub.3) serially connected to the first capacitive element at a first common node (36) to form a first series circuit, and a second capacitor (C.sub.4) serially connected to the second capacitive element at a second common node (38) to form a second series circuit. The detection circuit also includes switch a circuit (32) connected between the common nodes and a reference potential, a driver (30) for applying a drive signal across each series circuit, a line for activating the switch circuit (48) and a difference detector (34) for measuring the voltage difference between the common nodes.

Abstract: A transducer assembly includes first and second stators which are axially aligned with, and bear upon opposite sides of a proof mass. The stators and proof mass are clamped together by means of a sleeve having a side portion with spaced apart upper and lower flanges extending therefrom. The flanges bear against receiving surfaces on the stators with the sleeve under elastic deformation such that a compression force tending to reduce the spacing between the flanges is transmitted to the stators and proof mass as a controlled compressive axial preload.