Micromachined rate and acceleration sensor

• US 5,319,976 A
• Filed: 06/08/1993
• Issued: 06/14/1994
• Est. Priority Date: 02/08/1991
• Status: Expired due to Fees

• Current Assignee: L-3 Communications Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Alliedsignal Inc. (Honeywell International Inc.)
• Inventors: Hulsing, Rand H. II
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US08/073,817
• Time in Patent Office: 371 Days
• Field of Search: 73/505, 73/517 AV, 73/517 R, 73/510, 73/511
• US Class Current: 73/504.12
• 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: F02G 2250/18 Vuilleumier cycles
• CPC Class Codes: F02G 2253/03 Stem seals
• CPC Class Codes: F16F 2230/0052 Physically guiding or influencing
• CPC Class Codes: F16F 2230/34 Flexural hinges
• 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: G01C 19/5747 each sensing mass being connected to a driving mass, e.g. driving frames
• 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
• CPC Class Codes: Y10S 73/01 Vibration

Abstract

A sensor (10) is disclosed for measuring the specific force and angular rotation rate of a moving body and is micromachined from a silicon substrate (16). First and second accelerometers (32a and b) are micromachined from the silicon substrate (16), each having a force sensing axis (38) and producing an output signal of the acceleration of the moving body along its force sensing axis (38). The first and second accelerometers (32a and b) are mounted within the substrate (16) to be moved along a vibration axis (41). The first and second accelerometers (32a and b) are vibrated or dithered to increase the Coriolis component of the output signals from the first and second accelerometers (32a and b). A sinusoidal drive signal of a predetermined frequency is applied to a conductive path (92) disposed on each of the accelerometers. Further, magnetic flux is directed to cross each of the conductive paths (92), whereby the interaction of the magnetic flux and of the drive signal passing therethrough causes the desired dithering motion. A link (72) is formed within the silicon substrate (16) and connected to each of the accelerometers (32a and b), whereby motion imparted to one results in a like, but opposite motion applied to the other accelerometer (32). Further, a unitary magnet (20) and its associated flux path assembly direct and focus the magnetic flux through the first and second accelerometers (32a and b) formed within the silicon substrate (16).

Claims

1. Apparatus for measuring the specific force and angular rotation rate of a moving body, comprising:

a) a monolithic substrate having first and second substantially planar surfaces disposed substantially parallel to each other;

b) a fist accelerometer formed of said substrate and having a first force sensing axis for producing a first output signal indicative of the acceleration of the moving body along said first force sensing axis, said first accelerometer having a proof mass, a support frame, and at least one flexure connecting said proof mass to said support frame;

c) a second accelerometer formed of said substrate and having a second force sensing axis for producing a second output signal indicative of the acceleration of the moving body along said second force sensing axis, said second accelerometer having a proof mass, a support frame, and at least one flexure connecting said proof mass to said support frame;

d) a dither frame formed of said substrate;

e) mounting means formed of said substrate for mounting said first and second accelerometers to said dither frame such that said first and second force sensing axes are both oriented at the same angle with respect to said first and second surfaces and such that said first and second accelerometers can be moved along a vibration axis perpendicular to each of said first and second sensing axes;

f) drive means coupled to each of said first and second accelerometers for imparting a dithering motion thereto of a predetermined frequency along said vibration axis and second force sensing axes; and

g) said substrate having a rate axis perpendicular to each of said first and second force sensing axes and said vibration axis, whereby said first and second output signals have a Coriolis component indicative of the angular rotation of the moving body about said rate axis.

2. The measuring apparatus as claimed in claim 1, wherein said mounting means comprises first and second flexure means for mounting respectively said first and second accelerometers to said dither frame.

3. The measuring apparatus as claimed in claim 2, wherein said first and second flexure means comprise respectively first and second pairs of flexures.

4. The measuring apparatus as claimed in claim 3, wherein each flexure of said first and second pairs is an "S-bend" flexure.

5. The measuring apparatus as claimed in claim 3, wherein each flexure of said first and second pairs is of a selective length and cross-sectional dimension to render its flexure an "S-bend" flexure.

6. The measuring apparatus as claimed in claim 5, wherein said monolithic substrate is made of a material selected from the group consisting of quartz or silicon.

7. The measuring apparatus as claimed in claim 4, wherein said dither frame is of a rectangular configuration comprising first and third opposing members and second and fourth opposing members, said first and second flexure means being affixed respectively to said first and third members for respectively being connected to said support frames of said first and second accelerometers and said mounting said first and second accelerometers therefrom.

8. The measuring apparatus as claimed in claim 1, wherein said first force sensing axis extends in a direction opposite to that of said second sensing axes.

9. The measuring apparatus as claimed in claim 8, wherein there is included signal processing means coupled to said first and second accelerometers for processing their first and second output signals for canceling those signals introduced respectively into said first and second output signals by extraneous motion applied to said measuring apparatus.