Sensor mount vibration reduction
View Patent ↗Techniques are provided for reducing mount vibration in an inertial rate sensor (IRS). For example, if oscillation in an IRS's vibratory members, vibrating along a first axis, cause displacement in the IRS's mount along a second axis, the vibratory members can be aligned so that the vibratory members have some component of movement along the second axis during oscillation. This component of movement can help reduce the displacement of the IRS's mount along the second axis. It can further reduce sensitivity to changes in the boundary conditions of an IRS (e.g., vibrations and other movements at the mount from forces external to the IRS). Vibratory members further can have portions of increased mass at the vibratory members' tips, which can impact the alignment of the vibratory members. These examples, however, are not exhaustive.
1. An inertial rate sensor comprising:
a base; and
a plurality of vibratory members coupled with the base and positioned symmetrically about an axis of symmetry, wherein each vibratory member includes:
an elongate dimension extending outward from the base to a tip of the vibratory member; and
an axis of motion along which the vibratory member is configured to move when driven in oscillation, the axis of motion being perpendicular to the elongate dimension;
wherein the elongate dimension of each vibratory member is angled from the axis of symmetry such that each vibratory member, when driven in oscillation, includes a component of motion parallel to the axis of symmetry.
2. The inertial rate sensor as recited in claim 1 , wherein each vibratory member is tapered such that a lateral dimension of each vibratory member decreases from the base to the tip of the vibratory member.
3. The inertial rate sensor as recited in claim 1 , wherein the base and the plurality of vibratory members comprise a piezoelectric material.
4. The inertial rate sensor as recited in claim 1 , wherein each of the plurality of vibratory members includes a portion of increased mass at the tip of the vibratory member.
5. The inertial rate sensor as recited in claim 4 , wherein, for each of the plurality of vibratory members, the portion of increased mass is symmetric about an axis parallel to the elongate dimension of the vibratory member.
6. The inertial rate sensor as recited in claim 4 , wherein, for each of the plurality of vibratory members, the portion of increased mass is symmetric about an axis parallel to the axis of symmetry.
7. A tuning fork for use in an inertial rate sensor, the tuning fork comprising:
a base having a mounting area; and
two vibratory members coupled with the base and positioned symmetrically on opposite sides of an axis of symmetry, each vibratory member including:
an elongate dimension extending outward from the base to a tip of the vibratory member; and
an axis of motion along which the vibratory member is configured to move when driven in oscillation, the axis of motion being perpendicular to the elongate dimension and substantially coplanar with the axis of symmetry and the elongate dimension;
wherein the elongate dimension of each vibratory member is angled from the axis of symmetry such that each vibratory member, when driven in oscillation, includes a component of motion parallel to the axis of symmetry.
8. The tuning fork as recited in claim 7 , wherein each vibratory member is tapered such that a lateral dimension of each vibratory member decreases from the base to the tip of the vibratory member.
9. The tuning fork as recited in claim 7 , wherein the base and the plurality of vibratory members comprise a piezoelectric material.
10. The tuning fork as recited in claim 7 , wherein each of the plurality of vibratory members includes a portion of increased mass at the tip of the vibratory member.
11. The tuning fork as recited in claim 10 , wherein, for each of the plurality of vibratory members, the portion of increased mass is symmetric about an axis parallel to the elongate dimension of the vibratory member.
12. The tuning fork as recited in claim 10 , wherein, for each of the plurality of vibratory members, the portion of increased mass is symmetric about an axis parallel to the axis of symmetry.
13. The tuning fork as recited in claim 10 , wherein an angle between the elongate dimension of each vibratory member and the axis of symmetry is within a range of 1 to 3 degrees.
14. The tuning fork as recited in claim 10 , wherein an angle between the elongate dimension of each vibratory member and the axis of symmetry is configured to reduce vibrations at the mounting area when the two vibratory members are driven in oscillation.
15. The tuning fork as recited in claim 10 , further comprising a plurality of sense members coupled with the base, the sense members configured to detect rotation about a sensitive axis when the two vibratory members are driven in oscillation.
16. A structure for use in the inertial rate sensor, the structure comprising:
a body of piezoelectric material, the body including a base and a plurality of vibratory members, wherein:
the plurality of vibratory members are coupled with the base and positioned symmetrically about an axis of symmetry, each vibratory member including:
an elongate dimension extending outward from the base to a tip of the vibratory member;
a portion of increased mass at the tip of the vibratory member; and
an axis of motion along which the vibratory member is configured to move when driven in oscillation, the axis of motion being perpendicular to the elongate dimension and substantially coplanar with the axis of symmetry and the elongate dimension; and
the elongate dimension of each vibratory member is angled from the axis of symmetry such that the vibratory member, when driven in oscillation, includes a component of motion along the axis of symmetry.
17. The structure for use in the inertial rate sensor as recited in claim 16 , wherein, for each of the plurality of vibratory members, the portion of increased mass is symmetric about an axis parallel to the elongate dimension of the vibratory member.
18. The structure for use in the inertial rate sensor as recited in claim 16 , wherein, for each of the plurality of vibratory members, the portion of increased mass is symmetric about an axis parallel to the axis of symmetry.
19. The structure for use in the inertial rate sensor as recited in claim 16 , further comprising a plurality of sense members coupled with the body, the sense members configured to detect rotation about a sensitive axis when the plurality of vibratory members are driven in oscillation.
20. The structure for use in the inertial rate sensor as recited in claim 16 , wherein each vibratory member is tapered such that a lateral dimension of each vibratory member decreases from the base to the tip of the vibratory member.