Frame assembly and dither drive for a coriolis rate sensor
First Claim
1. Apparatus for producing signals indicative of both a Coriolis rate and an acceleration along a preferred axis while decoupling extraneous motions that would introduce errors in said signals, comprising:
- (a) a parallelogram frame including two accelerometers support surfaces attached to opposite ends of a flex member, the flex member including a plurality of flexures having parallel bending axes about which the frame pivots, two of the flexures that are disposed at opposite ends of one side of the flexure member having a cross axis that is substantially parallel to the accelerometer support surfaces;
(b) two accelerometers, each mounted on one of the accelerometer support surfaces and having a preferred axis for sensing acceleration that is aligned with one of said two flexures, and each further having a center of percussion that is rigidly coupled to the other by said two flexures and said one side of the flex member; and
(c) driving means, disposed adjacent to the parallelogram frame, for driving the accelerometers at a desired frequency, causing the accelerometers to vibrate back and forth in a direction substantially transverse to their preferred axes as the parallelogram frame pivots at the flexures.
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Accused Products
Abstract
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.
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Citations
22 Claims
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1. Apparatus for producing signals indicative of both a Coriolis rate and an acceleration along a preferred axis while decoupling extraneous motions that would introduce errors in said signals, comprising:
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(a) a parallelogram frame including two accelerometers support surfaces attached to opposite ends of a flex member, the flex member including a plurality of flexures having parallel bending axes about which the frame pivots, two of the flexures that are disposed at opposite ends of one side of the flexure member having a cross axis that is substantially parallel to the accelerometer support surfaces; (b) two accelerometers, each mounted on one of the accelerometer support surfaces and having a preferred axis for sensing acceleration that is aligned with one of said two flexures, and each further having a center of percussion that is rigidly coupled to the other by said two flexures and said one side of the flex member; and (c) driving means, disposed adjacent to the parallelogram frame, for driving the accelerometers at a desired frequency, causing the accelerometers to vibrate back and forth in a direction substantially transverse to their preferred axes as the parallelogram frame pivots at the flexures. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. Apparatus for producing Coriolis rate and acceleration signals relative to a preferred axis, while decoupling extraneous motions that would introduce errors in said signals, comprising:
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(a) a frame including two opposed and substantially parallel accelerometer mounting surfaces, and a plurality of members flexibly interconnecting the accelerometer mounting surfaces to permit their movement in opposite directions, in arcs about a common center, lines tangent said arcs being substantially perpendicular to the preferred axis of the apparatus; (b) two accelerometers, each mounted on one of the accelerometer mounting surfaces and having a preferred axis for sensing acceleration that is substantially parallel with the preferred axis of the apparatus; (c) means for rigidly coupling centers of percussion of the accelerometers; and (d) driving means for driving the accelerometer mounting surfaces to vibrate back and forth through said arcs. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. Apparatus for producing signals indicative of Coriolis rate about a rate axis, with reduced errors due to extraneous motions, comprising:
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(a) two accelerometer carriers disposed on opposite sides of a frame; (b) two accelerometers, each mounted on one of the accelerometer carriers, preferred axes of the accelerometers being substantially aligned in parallel and transverse to the rate axis; (c) two substantially parallel flex members, each extending between the two accelerometer carriers at opposite sides thereof, the flex members each including a cross brace disposed at their center, adapted for attaching the frame to a supporting structure, and further including a plurality of flexures having parallel bending axes, the flexures being disposed at the corners of a parallelogram, with one of the flexures connecting two sides of the parallelogram at each corner and one of the flexures disposed at each end of the cross brace and connecting to the centers of two sides of the parallelogram, the flexures at each end of one of said two sides of each flex member being oriented to provide maximum stiffness on a line between the two accelerometer carries and disposed so that the centers of mass of each accelerometer carrier and the accelerometer mounted thereon are aligned with the flexures at each end of said one side; and (d) drive means for applying a driving force to vibrate the two accelerometers back and forth in directions generally transverse to their preferred axes, by causing bending of the flex members about their bending axes. - View Dependent Claims (20, 21, 22)
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Specification