Frame assembly and dither drive for a coriolis rate sensor
First Claim
1. A method for mounting two accelerometers for use as a combined Coriolis rate and acceleration sensor, and decoupling extraneous motion that would introduce errors in an output from the sensor, comprising the steps of:
- (a) mounting the accelerometers on two opposed mounting pads so that a preferred axis of each accelerometer is aligned with the other;
(b) linking the opposed mounting pads in parallel alignment, with a flexing parallelogram frame enabling the accelerometers to vibrate back and forth in a direction transverse to their preferred axes;
(c) attaching a central portion of the parallelogram frame to a supporting structure about which the parallelogram frame flexibly pivots;
(d) rigidly coupling the two mounting pads along a path that extends in alignment with a line through a center of percussion associated with each accelerometer, insuring that both accelerometers are subjected to the same motion directed along their preferred axes.
2 Assignments
0 Petitions
Accused Products
Abstract
An apparatus for producing signals indicative of both a Coriolis rate and an acceleration along a preferred axis while decoupling extraneous vibration and motion that would introduce errors into the signals, and a driving mechanism for vibrating the apparatus at a dither frequency. The apparatus includes a parallelogram frame (50) including two accelerometer support surfaces (24, 26) on which are mounted two accelerometers (20 and 22) having their sensitive axes in parallel alignment. The accelerometer support surfaces are connected to opposite ends of a flex member (52), which includes six flexures (32, 34, 36, 38, 40, 42) having parallel bending axes. Two of the flexures (34, 38) are disposed at opposite ends of one side of each flexure member, and have a "long" axis that is substantially parallel to the sensitive axes of the accelerometers and aligned with a line connecting their centers of percussion. The centers of mass of the accelerometers and their associated supporting surfaces are coincident with the centers of percussion, and are rigidly connected by the two flexures and by one side (30) of each flex member. This solid metal path between the centers of percussion minimizes common mode errors. A driving mechanism (64) is connected to the parallelogram frame and is operative to drive the accelerometers at a desired frequency, causing them to vibrate back and forth in a direction substantially transverse to their sensitive axes. The driving mechanism includes a mounting plate (72) and a coil frame (66) on which are mounted two electromagnetic coils (70) having a "C" shaped core (80). The driving mechanism is mounted so that the core faces a pole piece (84) attached to the parallelogram frame and its moment of inertia is trimmed to equal that of the parallelogram frame. It is connected to the parallelogram by a link (88) and provides a reactionless driving force.
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Citations
13 Claims
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1. A method for mounting two accelerometers for use as a combined Coriolis rate and acceleration sensor, and decoupling extraneous motion that would introduce errors in an output from the sensor, comprising the steps of:
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(a) mounting the accelerometers on two opposed mounting pads so that a preferred axis of each accelerometer is aligned with the other; (b) linking the opposed mounting pads in parallel alignment, with a flexing parallelogram frame enabling the accelerometers to vibrate back and forth in a direction transverse to their preferred axes; (c) attaching a central portion of the parallelogram frame to a supporting structure about which the parallelogram frame flexibly pivots; (d) rigidly coupling the two mounting pads along a path that extends in alignment with a line through a center of percussion associated with each accelerometer, insuring that both accelerometers are subjected to the same motion directed along their preferred axes. - View Dependent Claims (2, 3, 4)
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5. In a Coriolis rate and acceleration sensor including two accelerometers, a method for decoupling extraneous motion that would introduce errors, comprising the steps of:
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(a) mounting the accelerometers on a frame including a plurality of flexible joints permitting the accelerometers to be vibrated back and forth with their preferred axes aligned in parallel; (b) orienting a plurality of the flexible joints so that they are aligned with the centers of percussion associated with the accelerometers, and with their bending axes and cross axes substantially transverse to the preferred axes of the accelerometers; and (c) rigidly coupling the two accelerometers along a path that extends in alignment with a line through their centers of percussion. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13)
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Specification