Triaxial angular rate and acceleration sensor

• US 5,396,797 A
• Filed: 12/08/1992
• Issued: 03/14/1995
• Est. Priority Date: 02/08/1991
• Status: Expired due to Term

• Current Assignee: Alliedsignal Inc.
• Original Assignee: Alliedsignal Inc.
• Inventors: Hulsing, Rand H. II
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US07/987,906
• Time in Patent Office: 826 Days
• Field of Search: 73/505, 73/510
• US Class Current: 73/504.04
• CPC Class Codes: F02G 1/044 having at least two working members, e.g. pistons, delivering power output
• CPC Class Codes: F02G 1/0445 Engine plants with combined cycles, e.g. Vuilleumier
• CPC Class Codes: F16L 37/24 in which the connection is made by inserting one member axially into the other and rotating it to a limited extent, e.g. with bayonet action
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/097 by vibratory elements
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/0828 the mass being of the paddle type being suspended at one of its longitudinal ends

Abstract

A triaxial sensor substrate is adapted for use in measuring the acceleration and angular rate of a moving body along three orthogonal axes. The triaxial sensor substrate includes three individual sensors that are arranged in the plane of the substrate at an angle of 120 degrees with respect to one another. Each sensor is formed from two accelerometers having their sensing axes canted at an angle with respect to the plane of the substrate and further being directed in opposite directions. The rate sensing axes thus lie along three orthogonal axes. In order to reduce or eliminate angular acceleration sensitivity, a two substrate configuration may be used. Each substrate includes three accelerometers that are arranged in the plane of the substrate at an angle of 120 degrees with respect to one another. The sensing axes of the accelerometers of the first substrate are canted at an angle with respect to the plane of the first substrate toward the central portion thereof so that they lie along three skewed axes. Similarly, the sensing axes of the accelerometers of the second substrate are canted at an angle with respect to the plane of the second substrate away from the central portion thereof so that they lie along same three but oppositely directed axes. The sensing axes of the first and second substrates are aligned to prevent angular acceleration sensitivity.

Claims

1. A sensor structure adapted for use in a triaxial angular rate and acceleration sensor comprising:

a first sensor stack including a first generally planar substrate, a first mass plate disposed over a first surface of said first substrate, a first damping plate disposed over a second surface of said first substrate, said second surface being opposite and generally parallel to said first surface, a second damping plate disposed over said mass plate, said first substrate having a first set of coplanar accelerometers formed therein, each accelerometer of said first set of accelerometers having a sensing axis canted at an angle with respect to the plane of said first substrate, said first set of accelerometers being arranged in the plane of said first substrate to place said sensing axes of said first set of accelerometers skewed to one another;

a second sensor stack including a second generally planar substrate, a second mass plate disposed over a first surface of said second substrate, a third damping plate disposed over a second surface of said second substrate, said second surface being generally parallel to said first surface, a fourth damping plate disposed over said mass plate, said second substrate including a second set of coplanar accelerometers formed therein, each of said second set of accelerometers having a sensing axis canted at an angle with respect to the plane of said second substrate, said second set of accelerometers being arranged in the plane of said second substrate to place said sensing axes of said second set of accelerometers skewed to one another, each of said second set of accelerometers being paired with a corresponding accelerometer of said first set of accelerometers, corresponding accelerometer pairs having sensing axes that are parallel or anti-parallel;

means for linking said first and second stacks so that said first and second sets of accelerometers dither at the same frequency.

2. A sensor structure as claimed in claim 1 wherein the sensing axes of said corresponding pairs of accelerometers are aligned.

3. A sensor structure as claimed in claim 1 wherein said first sensor stack comprises:

a hub portion;

a main frame portion;

a plurality of flexures connecting said hub portion to said main frame portion to allow said main frame portion to dither with respect to said hub portion.

4. A sensor structure as claimed in claim 3 wherein said second sensor stack comprises:

a further hub portion connected in fixed alignment with said hub portion of said first sensor stack;

a further main frame portion;

a further plurality of flexures connecting said further hub portion to said further main frame portion to allow said further main frame portion to dither with respect to said further hub portion.

5. A sensor structure as claimed in claim 4 wherein said means for linking comprises a stack link interconnecting said first and second sensor stacks.

6. A sensor structure as claimed in claim 5 wherein said stack link provides means for translating dither motion imposed on said main frame portion of said first sensor stack in a first direction into a dither motion on said main frame portion of said second sensor stack in a second direction opposite said first direction.

7. A sensor structure adapted for use in a triaxial angular rate and acceleration sensor comprising:

a first sensor stack including a first generally planar substrate, a first mass plate disposed over a first surface of said first substrate, a first damping plate disposed over a second surface of said first substrate, said second surface being opposite and generally parallel to said first surface, a second damping plate disposed over said mass plate, a hub portion, a main frame portion, a plurality of flexures connecting said hub portion to said main frame portion to allow said main frame portion to dither with respect to said hub portion, said first substrate having a first set of coplanar accelerometers formed therein, each accelerometer of said first set of accelerometers having a sensing axis canted at an angle with respect to the plane of said first substrate, said first set of accelerometers being arranged in the plane of said first substrate to place said sensing axes of said first set of accelerometers skewed to one another;

a second sensor stack including a second generally planar substrate, a second mass plate disposed over a first surface of said second substrate, a third damping plate disposed over a second surface of said second substrate, said second surface being generally parallel to said first surface, a fourth damping plate disposed over said mass plate, a further hub portion connected in fixed alignment with said hub portion of said first sensor stack, a further main frame portion, a further plurality of flexures connecting said further hub portion to said further main frame portion to allow said further main frame portion to dither with respect to said further hub portion, said second substrate including a second set of coplanar accelerometers formed therein, each of said second set of accelerometers having a sensing axis canted at an angle with respect to the plane of said second substrate, said second set of accelerometers being arranged in the plane of said second substrate to place said sensing axes of said second set of accelerometers skewed to one another, each of said second set of accelerometers being paired with a corresponding accelerometer of said first set of accelerometers, corresponding accelerometer pairs having sensing axes that are parallel or anti-parallel;

means for linking said first and second stacks so that said first and second sets of accelerometers dither at the same frequency, said means for linking including a stack link interconnecting said first and second sensor stacks,

said stack link provides means for translating dither motion imposed on said main frame portion of said first sensor stack in a first direction into a dither motion on said main frame portion of said second sensor stack in a second direction opposite said first direction;

said stack link including a first stepped member, a second stepped member directed opposite said first stepped member, a back to back, S-bending flexure unit connecting said first and second stepped members, first means for connecting said first stepped member to said main frame portion of said first sensor stack, second means for connecting said second stepped member to said further main frame portion of said second sensor stack, third means for connecting said first and second stepped members to said further hub portion.

8. A sensor structure as claimed in claim 7 wherein the sensing axes of said corresponding pairs of accelerometers are aligned.