Vibratory gyroscope

• US 5,912,524 A
• Filed: 12/23/1997
• Issued: 06/15/1999
• Est. Priority Date: 10/28/1994
• Status: Expired due to Term

• Current Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Tomikawa, Yoshiro, Satoh, Akira, Ohnishi, Kazumasa
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US08/997,248
• Time in Patent Office: 539 Days
• Field of Search: 310/311, 310/312, 310/321, 310/333, 310/367, 310/370, 310/329, 73/514.34
• US Class Current: 310/321
• CPC Class Codes: G01C 19/5607 using vibrating tuning forks double-ended tuning forks using planar vibrating masses suspended at opposite ends G01C19/5719

Abstract

A vibratory gyroscope including an elongated vibrator having a central (neutral) axis (Y-axis), a drive unit for deforming the first direction such that the vibrator vibrates in a first (X) direction, an added mass attached to the vibrator at a position offset from the central axis in a second (Z) direction, and a detector formed on the vibrator. Rotation of the vibratory gyroscope about the second (Z) direction during vibration in the second direction causes Coriolis force to acting on the added mass in a direction parallel to the central axis. Because the added mass is offset from the central axis, a resulting vibration in the second (Z) direction is produced, which is detected by the detector. With this arrangement, the central axis of the vibrator is placed in parallel with the surface of rotation of the rotating system. Thus, rotations about two or three axes in each direction can be detected in such a manner that noise generation is prevented.

Claims

1. A vibratory gyroscope comprising:

an elongated vibrator having a first end, a second end, a first center of gravity, and a central axis passing from the first end to the second end through the first center of gravity;

drive means formed on the vibrator for deforming said vibrator in response to a signal having a predetermined frequency such that a portion of the vibrator located adjacent one of the first and second ends vibrates in a first direction perpendicular to the central axis;

a projection disposed on the portion of the vibrator, the projection having a second center of gravity which is displaced from the central axis such that rotation of the vibrator about an axis extending in a second direction perpendicular to the central axis during vibration of the vibrator in the first direction causes Coriolis force to act on said projection in a direction parallel to said central axis, thereby causing vibration of said vibrator in the first direction or in the second direction, and

detection means formed on the vibrator for detecting said vibration of said vibrator in the first direction or in the second direction;

wherein the first direction is perpendicular to the second direction.

2. A vibratory gyroscope comprising:

a plate-like vibrator having first and second opposing surfaces, a fixed end connected to a support member, a free end and a central axis extending in a direction parallel to the first and second surfaces between the fixed end and the free end;

drive means located on the first and second surfaces for deforming said vibrator in response to a signal having a predetermined frequency such that a portion of the vibrator adjacent the free end vibrates in a first direction perpendicular to the central axis;

an added mass protruding from one of the first and second surfaces, the added mass having a center of gravity which is displaced from the central axis such that rotation of the vibrator about an axis extending in a second direction during vibration of the vibrator in the first direction causes Coriolis force to act on the added mass in a direction parallel to said central axis, thereby creating a bending moment causing the vibrator to bend in the first direction or in the second direction, and

detection means formed on the first and second surfaces of the vibrator for detecting said bending of said vibrator in the first direction or in the second direction,

wherein the second direction is perpendicular to the central axis and to the first direction.

3. A vibratory gyroscope comprising:

a base;

a first plurality of vibrators having fixed ends integrally connected to the base and free ends, each of the first plurality of vibrators having center of gravity and a central axis extending from the fixed end to the free end through the center of gravity;

a second plurality of vibrators having fixed ends integrally connected to the base and free ends, each of the second plurality of vibrators having center of gravity and a central axis extending from the fixed end to the free end through the center of gravity;

first drive means disposed on the first plurality of vibrators for deforming and vibrating said first plurality of said vibrator in a first direction perpendicular to the central axes in response to a signal having a predetermined frequency;

a first plurality of added masses, each added mass being disposed at the free end of one of the first plurality of vibrators and having a center of gravity which is displaced from the central axis such that Coriolis force caused by rotation of the vibratory gyroscope about an axis extending in the second direction causes the first plurality of vibrators to vibrate in the first direction;

first detection means disposed on the first plurality of vibrators for detecting said vibration in said first direction resulting from Coriolis force caused by rotation of the vibratory gyroscope about an axis extending in the second direction;

second detection means for detecting a vibration component applied to said first plurality of vibrators in a second direction perpendicular to said first direction resulting from Coriolis force caused by rotation of the vibratory gyroscope about an axis extending parallel to the central axis;

second drive means disposed on the second plurality of vibrators for deforming and vibrating said second plurality of said vibrator in the second direction in response to a signal having a predetermined frequency;

a second plurality of added masses, each added mass being disposed at the free end of one of the second plurality of vibrators and having a center of gravity which is displaced from the central axis such that Coriolis force caused by rotation of the vibratory gyroscope about an axis extending in the first direction causes the second plurality of vibrators to vibrate in the second direction; and

third detection means for detecting deformation and vibrations of said second plurality of vibrators in said second direction resulting from Coriolis force caused by rotation of the vibratory gyroscope about an axis extending in the first direction.

4. A vibratory gyroscope according to claim 3, wherein said vibrator includes a first vibrator integrally connected to a plate-like base, the base being located at the fixed end of the vibrator, and said vibratory gyroscope further comprises:

a second vibrator integrally connected to the base and extending parallel to the first vibrator, the first and second vibrators being separated by a groove, the second vibrator having a second central axis which is parallel to the central axis of the first vibrator;

wherein said second vibrator includes an added mass protruding from a surface thereof, the added mass having a center of gravity which is displaced from the second central axis.