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EP-4741765-A2 - ANNULAR MICROELECTROMECHANICAL RATE SENSOR

EP4741765A2EP 4741765 A2EP4741765 A2EP 4741765A2EP-4741765-A2

Abstract

A microelectromechanical angular rate sensor (100) has a flexible ring structure (110) which forms a circle at rest and is suitable for performing an excitation oscillation substantially parallel to the plane of the circle over a substrate, to which a detection oscillation generated by the Coriolis force is superimposed when the ring structure (110) is rotated, and at least one coupling structure (120) which is connected to the ring structure (110) and is designed such that it is suitable, together with electrodes (130) fixed on the substrate, to compensate for a quadrature error of the angular rate sensor (100).

Inventors

  • RENDE, Jan Daniel

Assignees

  • Northrop Grumman LITEF GmbH

Dates

Publication Date
20260513
Application Date
20230516

Claims (10)

  1. Microelectromechanical gyroscope (100) with a flexible ring structure (110) which forms a circle at rest and is suitable for performing an excitation oscillation essentially parallel to the plane of the circle above a substrate, to which a detection oscillation generated by the Coriolis force is superimposed when the ring structure (110) is rotated; and at least one coupling structure (120) which is connected to the ring structure (110) and is designed in such a way that it is suitable, together with electrodes (130) fixed on the substrate, to compensate for a quadrature error of the rotation rate sensor (100), wherein at least two of the coupling structures (120) are coupled to each other in such a way that their movements are coupled to each other.
  2. Gyroscopic rate sensor (100) according to claim 1, further comprising first spring elements (140) that connect the ring structure (110) to the substrate; wherein which attack at least one coupling structure (120) and the first spring elements (140) on the same side of the ring structure (110).
  3. Rotation rate sensor (100) according to one of the preceding claims, wherein The gyroscope (100) has a plurality of coupling structures (120) that are evenly distributed along the circumferential direction of the ring structure (110).
  4. Rotation rate sensor (100) according to one of the preceding claims, wherein Electrodes (132) for compensating quadrature errors are in electrical interaction with parts of the coupling structures (120), which extend essentially in the radial direction of the ring structure (110).
  5. Rotation rate sensor (100) according to one of the preceding claims, wherein the coupling structures (120) are designed as frames which are connected on a first side (122) to the ring structure (110) and on a second opposite side (124) to the substrate; and at least part of the electrodes (130) fixed to the substrate are formed within the frame.
  6. Rotation rate sensor (100) according to claim 5, wherein the electrodes (132) for compensating quadrature errors in electrical interaction with third sides (126) of the frames, which extend essentially in the radial direction of the ring structure (110).
  7. Rotation rate sensor (100) according to claim 6, wherein the first and second sides of the frames (122, 124) are longer than the third sides of the frames (126).
  8. Rotation rate sensor (100) according to one of the preceding claims, wherein the coupling structures (120) are designed such that they are suitable to generate the excitation oscillation and/or to measure the detection oscillation together with electrodes (134) fixed on the substrate.
  9. Rotation rate sensor (100) according to one of the preceding claims, further comprising second spring elements (150) that connect the coupling structures (120) to the ring structure (110); wherein the second spring elements (150) are deformable in the radial direction of the ring structure (110) in such a way that a radial deflection of the coupling structures (120) leads to a greater radial deflection of the ring structure (110).
  10. Rotation rate sensor (100) according to one of the preceding claims, further comprising third spring elements (160) that connect the coupling structures (120) to the substrate.

Description

The present invention relates to ring-shaped microelectromechanical angular rate sensors. Ring-shaped microelectromechanical angular rate sensors operate on the principle that a closed structure, typically designed as a circle or ring, is set into vibration parallel to the substrate plane. When the ring is rotated about an axis perpendicular to the substrate plane, the ring's vibration generates a Coriolis force on the individual mass points of the ring. This results in the superposition of another vibration, the amplitude of which depends on the rotation rate. Since the direction of this detection vibration is essentially predetermined by the ring's position and the excitation vibration, and the parameters of the excitation vibration are also known, the detection vibration can be read out to determine the angular rate. In practice, plate electrodes positioned along the ring circumference are often used to excite and read out the vibrations. However, this is space-consuming and does not meet all the requirements of the angular rate sensor. Such plate electrodes can also be used to compensate for so-called quadrature errors, which microelectromechanical sensors often exhibit due to unavoidable manufacturing tolerances. However, this presents a problem: electrode plates placed externally along the ring's circumference are limited in terms of electrode area. Since a larger electrode area allows for the input and output of a larger signal, the use of external electrode plates is disadvantageous. Furthermore, with external electrode plates, it is not always possible to optimally design the excitation and output electrodes. The object of the present invention is therefore to provide ring-shaped microelectromechanical angular rate sensors with a large electrode area, which are compact in design and which allow compensation of quadrature errors without restricting the possibility of exciting the ring of the angular rate sensor or reading out vibrations. This problem is solved by the subject matter of the claims. A microelectromechanical angular rate sensor has a flexible ring structure that forms a circle at rest and is capable of performing an excitation oscillation essentially parallel to the plane of the circle above a substrate. When the ring structure is rotated, a detection oscillation generated by the Coriolis force is superimposed on this excitation oscillation. The angular rate sensor also has at least one coupling structure connected to the ring structure and configured to compensate for a quadrature error of the angular rate sensor in conjunction with electrodes fixed on the substrate. Therefore, attempts to compensate for quadrature errors via plate electrodes or similar devices acting directly on the ring structure of the angular rate sensor are no longer made. Instead, a coupling structure is connected to the ring structure, which can be subjected to compensating forces. The coupling structure then transmits these compensating forces to the ring structure, thereby compensating for quadrature errors. The specific design of the coupling structure is arbitrary, as long as the movements of the coupling structure caused by the compensating forces are transmitted to the ring structure to a sufficient degree to allow for a controllable and measurable influence on the ring structure's movements by adjusting the strength of the compensating forces. Due to the small vibration amplitudes typically found in microelectromechanical devices, a first-approximate compensation is usually sufficient. Furthermore, the use of the coupling structure allows for a freer placement and design of electrodes, thus providing a larger overall electrode area and enabling an advantageous design of electrodes with different functions, such as excitation and readout electrodes. In particular, the use of the coupling structure, especially with appropriate design of the spring stiffnesses of the various components of the angular rate sensor, makes it possible to achieve a greater amplitude of vibrations induced by the ring structure than the amplitude of vibrations induced by the coupling structure itself. This can also be used for advantageous electrode design, for example, to achieve smaller gap spacings or operation in the linear range. The gyroscope can further include initial spring elements that connect the ring structure to the substrate, with at least one coupling structure and the initial spring elements acting on the same side of the ring structure. The ring structure is thus connected to the substrate via spring elements. This ensures that the ring structure can oscillate as freely as possible. All spring elements act on one side of the ring structure, i.e., either from the inside or the outside, to guarantee a force- and moment-free coupling with respect to the substrate. The one or more coupling structures then act on the same side as the spring elements; if necessary, the connection of the coupling structures is also made