Planar inertial measurement units based on gyros and accelerometers with a common structure
First Claim
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1. A planar, integrated inertial measurement unit (IMU) comprising a plurality of inertial measurement instruments that are based on a common structure, the IMU comprising:
- at least two coplanar inertial measurement instruments, each instrument comprising;
a case;
a planar outer member coupled to the case by flexures, and that is driven angularly to oscillate about a drive axis with respect to the case; and
a planar inner member coplanar with the outer member and coupled to the outer member by flexures, and that rotates about an output axis that is orthogonal to the drive axis in response to the acceleration or rotation rate of the IMU.
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Abstract
Inertial Measurement Units based on integrated designs to reduce alignment and assembly costs. Integration also leads to performance improvement, increased miniaturization and simplification as well as reduced cost. Also disclosed are gyroscopes and accelerometers that are identical, yet by their mechanization, can be made to act as separate sensors. Miniaturization and simplification is improved by combining instruments that can share a common member. Savings in space and complexity are also possible in the electronics when elements are shared.
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Citations
49 Claims
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1. A planar, integrated inertial measurement unit (IMU) comprising a plurality of inertial measurement instruments that are based on a common structure, the IMU comprising:
at least two coplanar inertial measurement instruments, each instrument comprising;
a case;
a planar outer member coupled to the case by flexures, and that is driven angularly to oscillate about a drive axis with respect to the case; and
a planar inner member coplanar with the outer member and coupled to the outer member by flexures, and that rotates about an output axis that is orthogonal to the drive axis in response to the acceleration or rotation rate of the IMU. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A planar, integrated gyroscope inertial measurement instrument, comprising:
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a planar case;
a planar outer member coplanar with the case and coupled to the case by flexures, and that is driven with respect to the case by integral capacitive comb drives;
a planar inner member coplanar with the outer member and coupled to the outer member by flexures, and that moves with respect to the outer member in response to the rotation rate of the gyroscope; and
comb interleaved pickoffs defined in part on the outer member and in part on the inner member, for detecting motion of the inner member relative to the outer member. - View Dependent Claims (22, 23, 24)
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25. A planar, integrated inertial measurement unit (IMU) based on a common structure and comprising a plurality of inertial measurement instruments, the IMU comprising:
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at least seven separate inertial measurement instruments, each inertial measurement instrument having a driven member and a sense member, wherein the sense members of all such inertial measurement instruments are separate from one another, the instruments comprising at least two planar gyroscopes and at least five planar accelerometers, all arranged about the center of the IMU;
wherein four of the accelerometers are arranged in the IMU such that their sense members are at equal radial distances from the center of the IMU, and arranged such that as a group they measure both centrifugal and linear accelerations.
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26. A planar, integrated inertial measurement unit (IMU) based on a common structure and comprising a plurality of inertial measurement instruments, the IMU comprising:
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at least seven separate inertial measurement instruments, each inertial measurement instrument having a driven member and a sense member, wherein the sense members of all such inertial measurement instruments are separate from one another, the instruments comprising at least two planar gyroscopes and at least five planar accelerometers, all arranged about the center of the IMU;
wherein four of the accelerometers are arranged in the IMU such that their sense members are at equal radial distances from the center of the IMU, and are arranged such that as a group they measure both angular and linear accelerations.
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27. A planar, integrated inertial measurement unit multisensor, comprising:
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a case;
a planar outer member coupled to the case by flexures, and that is rotationally oscillated with respect to the case in and out of the plane about a drive axis in the plane;
a planar inner member coplanar with the outer member and coupled to the outer member by a plurality of flexures, and that oscillates rotationally in the plane about an axis that is normal to the plane in response to rotation rate of the IMU multisensor; and
a pendulous mass carried by the inner member and located along the drive axis, wherein the pendulous mass rotates about an axis that is normal to the plane in response to acceleration.
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28. A planar, integrated inertial measurement unit (IMU) comprising a plurality of inertial measurement instruments that are based on a common structure, the IMU comprising:
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a plurality of physically separate, coplanar inertial measurement instruments, each instrument comprising;
a case;
a planar outer member coupled to the case by flexures, and that is driven angularly to oscillate about a drive axis with respect to the case; and
a planar inner member coplanar with the outer member and coupled to the outer member by flexures, and that rotates about an output axis that is orthogonal to the drive axis in response to the acceleration or rotation rate of the IMU; and
a common support substrate supporting each of the inertial measurement instruments. - View Dependent Claims (29)
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30. A planar, integrated inertial measurement unit (IMU) comprising a plurality of inertial measurement instruments that are based on a common structure, the IMU comprising:
at least two coplanar inertial measurement instruments, each instrument comprising;
a case;
a planar outer member coupled to the case by flexures, and that is driven with respect to the case; and
a planar inner member coplanar with the outer member and coupled to the outer member by flexures, and that rotates in response to the acceleration or rotation rate of the IMU;
wherein the outer member of at least two said coplanar inertial measurement units is common. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49)
Specification