Inertial unit with several detection axes

• US 9,038,460 B2
• Filed: 04/30/2012
• Issued: 05/26/2015
• Est. Priority Date: 05/02/2011
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Original Assignee: Commissariat A L'Energie Atomique E Aux Energies Alternatives
• Inventors: Walther, Arnaud
• Primary Examiner(s): Williams, Hezron E
• Assistant Examiner(s): Shabman, Mark A
• Application Number:
  US13/459,592
• Publication Number:
  US 20120279300A1
• Time in Patent Office: 1,121 Days
• Field of Search: 735/040.3
• US Class Current: 73/504.03
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure
• CPC Class Codes: G01C 19/5747 each sensing mass being connected to a driving mass, e.g. driving frames
• CPC Class Codes: G01P 15/08 with conversion into electric or magnetic values
• CPC Class Codes: G01P 15/18 in two or more dimensions

Abstract

Inertial unit for the measurement of accelerations and/or rotations comprising four sensors, spread out on two intersecting axes, each sensor comprising two inertial masses, each inertial mass comprising a moveable excitation part and a moveable detection part, the moveable excitation parts of a sensor being separate from those of the other sensors, said unit also comprising means for exciting the excitation parts of the sensors and means for detecting the movement of the detection parts, the two inertial masses of each sensor) being mechanically coupled, the four sensors being coupled by elastically deformable mechanical coupling means and able to transmit the excitation vibrations from one axis to the other.

Claims

1. An inertial unit for the measurement of accelerations and/or rotations comprising:

at least four sensors, at least one of which is an accelerometer, distributed by pairs on at least two intersecting axes, including a first pair of sensors on a first axis and a second pair of sensors on a second axis, the second axis intersecting the first axis, each sensor comprising two inertial masses, each inertial mass comprising a moveable excitation part and a moveable detection part, the moveable excitation parts of a sensor being separate from those of the other sensors, the two inertial masses of each sensor being mechanically coupled by an intra-sensor coupling structure,

excitation means for exciting the excitation parts of the sensors and

detection means for detecting the movement of the detection parts,

a control unit to control the excitation means and to control the detection means,

a mechanical inner-sensor coupling structure between the four sensors, said inner-sensor coupling structure being elastically deformable and able to transmit the excitation vibrations from one axis to the other,

wherein at least one of the intra-sensor coupling structures is a strong coupling means.

2. The inertial unit according to claim 1, in which all of said intra-sensor coupling structures are strong coupling means.

3. The inertial unit according to claim 1, in which said inner-sensor coupling structures are situated at the intersection of the axes bearing the two pairs of sensors, the two sensors of each pair being arranged on either side of said inner-sensor coupling structure.

4. The inertial unit according to claim 1, in which the at least two axes are perpendicular.

5. The inertial unit according to claim 1, in which the inner-sensor coupling structure is a strong coupling structure.

6. The inertial unit according to claim 1, in which the inner-sensor coupling structure is connected to the excitation part of one of the masses of each sensor.

7. The inertial unit according to claim 1, in which the inner-sensor coupling structure comprises an assembly of beams comprising at least one closed pattern.

8. The inertial unit according to claim 7, in which the closed pattern has the shape of a diamond, each top of said diamond being connected to a mass of a sensor.

9. The inertial unit according to claim 1, in which the intra-sensor coupling structures connect the two excitation parts of each sensor.

10. The inertial unit according to claim 1, in which the excitation part of each sensor is excitable in a single direction.

11. The inertial unit according to claim 1, comprising one or more gyrometers and/or one or more accelerometers, said at least gyrometer and/or accelerometer being able to measure a rotation and/or an acceleration along an axis called a detection axis.

12. The inertial unit according to claim 11, comprising a rigid rod in rotation around an axis orthogonal to the detection axis, said rigid rod connecting the two detection parts of the masses of the accelerometer.

13. The inertial unit according to claim 11 or 12, the intra-sensor coupling structure between two masses of a gyrometer forming a strong coupling in antiphase, and the intra-sensor coupling structure between two masses of an accelerometer forming a strong coupling in phase.

14. The inertial unit according to claim 13, in which the intra-sensor coupling structure in antiphase comprises a closed assembly of beams.

15. The inertial unit according to claim 13, in which the intra-sensor coupling structure in phase comprises a rigid connection, the two masses of a same accelerometer acting as a single mass.

16. The inertial unit according to claim 12, the intra-sensor coupling structure between two masses of a gyrometer forming a strong coupling in antiphase, and the intra-sensor coupling structure between two masses of an accelerometer forming a strong coupling in phase.

17. The inertial unit according to claim 16, in which the intra-sensor coupling structure in antiphase comprises a closed assembly of beams.

18. The inertial unit according to claim 16 or 17, in which the intra-sensor coupling structure in phase comprises a rigid connection, the two masses of a same accelerometer acting as a single mass.

19. The inertial unit according to claim 11, in which the gyrometers(s) comprise a rigid rod in rotation around the detection axis around which the rotation is to be detected connecting the detection parts of the inertial masses.

20. The inertial unit according to claim 1, in which at least one of the sensors is replaced by an object not supplying a measurement on the acceleration or the rotation and ensuring a balancing of the inertial unit.

21. The inertial unit according to claim 1, comprising three pairs of sensors, the sensors of each pair being aligned on an axis , two of the axes being parallel and the other axis being intersecting to the two parallel axes, a first inner-sensor coupling structure being provided at the level of each intersection of one of the axes parallel with the other axis and a second inner-sensor coupling structure being provided between the first inner-sensor coupling structure.

22. The inertial unit according to claim 21, comprising three gyrometers and three accelerometers, the three gyrometers being connected directly to the first inner-sensor coupling structure different from the first inner-sensor coupling structure to which are connected directly the three accelerometers.

23. The inertial unit according to claim 1, comprising eight sensors, the inner-sensor coupling means comprising an assembly of eight patterns in juxtaposed diamond shape, the patterns being connected by one of their tops in a point constituting a centre of symmetry of the coupling structure, so as to have patterns opposite and aligned two by two, the tops of the opposite patterns at the centre of symmetry being intended to be each integral with a mass of eight sensors.

24. The inertial unit according to claim 1, in which the excitation means are of electrostatic, piezoelectric or magnetic type and the detection means are of capacitive, piezoelectric, magnetic or piezoresistive type.

25. The inertial unit according to claim 1, in which the detection means are chosen of same type for all of the sensors.

26. The inertial unit according to claim 1, in which the control unit comprises a single control loop in excitation for all of sensors and means for detecting the displacement of the detection parts.

27. The inertial unit according to claim 1, in which the control unit comprises means for reading the detection means of the different sensors by time division multiplexing.

28. The inertial unit according to claim 1, in which the strong coupling means mechanically couples two inertial masses of the accelerometer such that the two inertial masses of the accelerometer move with a same amplitude.

29. The inertial unit according to claim 28, in which the strong coupling means includes a rigid rod connecting the two inertial masses of the accelerometer.

30. The inertial unit according to claim 1, in which at least one of the four sensors is a gyroscope and the strong coupling means mechanically couples two inertial masses of the gyroscope such that the two inertial masses of the gyroscope move apart or closer together in phase along a same axis and with a same amplitude.

31. The inertial unit according to claim 30, in which the strong coupling means includes a rigid rod connecting the two inertial masses of the gyroscope.