Accelerometer system
First Claim
1. An inertial platform accelerometer cluster having three orthogonal axes, said accelerometer cluster comprising an accelerometer system associated with each of the three orthogonal axes, each accelerometer system including:
- at least one means for sensing inertial accelerations, said means for sensing inertial accelerations being responsive to accelerations in a frequency range extending down to zero Hertz;
a pair of means for sensing vibrational accelerations, each of said means for sensing vibrational accelerations being responsive to vibrational acceleration in a range of relatively higher frequencies causing coning and sculling effects in the inertial accelerometers of said cluster, said pair of means for sensing vibrational accelerations being disposed equidistantly about a centre of percussion common to the other orthogonal axes and the centre of gravity of the cluster; and
signal processing means operable to produce from the sum of the signals from said pair of means for sensing vibrational accelerations a sum signal representative of vibrational acceleration of the cluster along said axis and operable to produce from the difference between the signals from said pair of means for sensing vibrational accelerations a difference signal representative of the angular acceleration of the cluster about one of said orthogonal axes.
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Abstract
An inertial platform accelerometer cluster (FIG. 1) comprises a cluster of gyro and accelerometer system triads disposed in a cluster housing 10 to detect motion along and about orthogonal x, y and z axes. The orthogonal accelerometer systems each comprises a pair of codirectional accelerometers e.g. 15x, 15'"'"'x having an operating bandwidth from 0 to several KHz mounted on the housing walls equidistant from a point 14, which represents a common center of percussion to all pairs, at the center of gravity of the cluster. The analogue output signals of each accelerometer pair are scaled, summed and differenced to provide `sum` and `difference` signals which represent respectively acceleration in the sensitive direction and angular acceleration about an orthogonal axis. The sum and difference signals can be used in analogue correction generating circuitry to obtain correction signals for coning and sculling effects, for which responses at high-frequency are called for, while economizing on computer time and capacity. Furthermore the coincidence of the center of percussion for all accelerometer pairs eliminates size effect errors from the `sum` signal which is employed for the normal inertial platform computations. Separate high- and low-frequency responsive accelerometers may be used.
241 Citations
14 Claims
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1. An inertial platform accelerometer cluster having three orthogonal axes, said accelerometer cluster comprising an accelerometer system associated with each of the three orthogonal axes, each accelerometer system including:
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at least one means for sensing inertial accelerations, said means for sensing inertial accelerations being responsive to accelerations in a frequency range extending down to zero Hertz; a pair of means for sensing vibrational accelerations, each of said means for sensing vibrational accelerations being responsive to vibrational acceleration in a range of relatively higher frequencies causing coning and sculling effects in the inertial accelerometers of said cluster, said pair of means for sensing vibrational accelerations being disposed equidistantly about a centre of percussion common to the other orthogonal axes and the centre of gravity of the cluster; and signal processing means operable to produce from the sum of the signals from said pair of means for sensing vibrational accelerations a sum signal representative of vibrational acceleration of the cluster along said axis and operable to produce from the difference between the signals from said pair of means for sensing vibrational accelerations a difference signal representative of the angular acceleration of the cluster about one of said orthogonal axes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification