Three-axis microelectromechanical gyroscope with improved performance
By introducing a specially configured elastic coupling element into the MEMS gyroscope, the movement limitation between the driving mass and the sensing mass is solved, achieving high sensitivity and low power consumption of the three-axis MEMS gyroscope and meeting the performance requirements of modern applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-22
- Publication Date
- 2026-03-27
AI Technical Summary
Existing MEMS gyroscopes have limitations in their design regarding the movement between the driving mass and the sensing mass, resulting in large area footprint, high power consumption, and insufficient sensitivity, making it difficult to meet the requirements of modern applications for vibration suppression and sensitivity.
A three-axis MEMS gyroscope structure is adopted. By introducing a specially configured elastic coupling element between the driving mass and the sensing mass, the translational movement of the driving mass and the rotational movement of the sensing mass are coupled in the same horizontal plane. The angular velocity is sensed by utilizing the Coriolis force, and the sensing sensitivity and resonant frequency are optimized by adjusting the stiffness and length of the coupling element.
This approach achieves improved sensitivity and vibration suppression of MEMS gyroscopes while reducing footprint and power consumption, and reduces interference between sensing axes, thus meeting the performance requirements of modern applications.
Smart Images
Figure CN121739988A_ABST
Abstract
Description
Cross-reference to related applications
[0001] This application claims priority to Italian Patent Application No. 102024000021338, filed on September 25, 2024, the entire contents of which are incorporated herein by reference to the full extent permitted by law. Technical Field
[0002] This disclosure relates to a microelectromechanical gyroscope with improved performance; in particular, the following discussion is directed to a three-axis gyroscope capable of sensing angular velocities acting along three orthogonal axes (commonly referred to as roll, pitch, and yaw axes). Background Technology
[0003] As is well known, current microfabrication techniques allow the fabrication of microelectromechanical systems (MEMS) from semiconductor material layers, which are deposited (e.g., polysilicon layers) or grown (e.g., epitaxial layers) over a sacrificial layer that is removed by chemical etching.
[0004] Inertial sensors, accelerometers, and gyroscopes with this technology are increasingly used in various fields, such as automotive, inertial navigation, and high-end consumer electronics portable devices (e.g., for optical image stabilization (OIS)).
[0005] In particular, microelectromechanical gyroscopes (hereinafter referred to as MEMS gyroscopes) made of semiconductor materials using MEMS technology are well known.
[0006] These MEMS gyroscopes operate using Coriolis acceleration based on the law of relative acceleration. When a certain angular velocity (the value of which is to be detected) is applied to a moving mass driven at a linear velocity, the moving mass is subjected to an apparent force (i.e., the Coriolis force), which causes displacement of the moving mass in a direction perpendicular to the driving linear velocity component and perpendicular to the axis of rotation. The moving mass is supported by elastic elements that allow both the driving displacement and the sensed displacement in the direction of the apparent force. According to Hooke's law, the displacement is proportional to the apparent force, such that the Coriolis force and the angular velocity of the rotation that generates the force can be determined from the sensed displacement of the moving mass.
[0007] For example, the sensed displacement of the moving mass can be sensed capacitively. For example, the sensed displacement of the moving mass can be sensed capacitively by determining, under resonant conditions, the capacitance change caused by the movement of the moving sensing electrode, which is integrated with (or formed by a portion of) the moving mass and coupled (e.g., in a so-called “parallel plate” configuration or in an interdigital configuration) to the fixed or stator sensing electrode.
[0008] In particular, such as Figure 1A and Figure 1B Schematically, a known MEMS gyroscope typically includes a microelectromechanical structure having at least one driving mass 2 (e.g., in the shape of a frame rectangle) that is translated within the horizontal plane xy (corresponding to the main extension plane of the same driving mass), for example, along the horizontal axis y. Figure 1A As indicated by the middle arrow.
[0009] At least one sensing mass block 4 is coupled to the driving mass block 2 and is provided with an anchoring structure 5 for anchoring to a corresponding substrate (not shown herein), the anchoring structure 5 being centrally arranged relative to the sensing mass block 4.
[0010] During the driven movement, the sensing mass 4 is rigidly coupled to the driving mass 5 to perform rotational movement in the horizontal plane xy about the anchoring structure 5 (as indicated by the rotation arrow); specifically, this movement involves a linear motion component along the horizontal axis x at the end portion of the sensing mass 4 (again, as indicated by the rotation arrow). Figure 1A (As indicated by the middle arrow).
[0011] like Figure 1B As shown, due to the Coriolis force, the sensing mass 4 is thus able to perform a sensing movement, which corresponds to a rotation about the axis of rotation A outside the horizontal plane xy. In the example, the axis of rotation A is arranged at the center position parallel to the horizontal axis x.
[0012] It has been shown that this arrangement of the sensing mass block 4, which rotates around the central anchor, has advantages in resisting interference vibrations.
[0013] In known solutions, the coupling between the driving mass 2 and the sensing mass 4 is typically achieved by a single elastic coupling element (or “spring”) 6, which is centrally positioned between the driving mass 2 and the sensing mass 4, has a linear extension, is located at the axis of rotation A, and extends along the same axis of rotation A.
[0014] Specifically, as previously described, the elastic coupling element 6 couples the (translational) driven movement with the (rotational) sensing movement.
[0015] While the above solutions are undoubtedly efficient and superior, the aforementioned coupling mechanisms may still have some problems.
[0016] Specifically, in this solution, the direction of the driving movement must be perpendicular to the rotation axis A (the sensed movement of the rotation outside the horizontal plane xy occurs around this axis).
[0017] Therefore, the design of the microelectromechanical structure of a MEMS gyroscope is limited by the existence of such relative movement between the driving mass and the sensing mass.
[0018] Furthermore, since the aforementioned flexible coupling mechanism has a significant impact on the characteristics and performance of the gyroscope (e.g., in terms of area footprint, detection sensitivity, and operating mode frequency), a more flexible solution is needed in terms of the design and mutual positioning of the driving mass and sensing mass.
[0019] Overall, there is a need for a MEMS gyroscope, particularly a triaxial MEMS gyroscope, that offers reduced footprint and power consumption, along with improved vibration suppression (which refers to interference with the sensing of the target's angular velocity). In fact, the applications that have developed and become widespread in recent years have placed even more stringent demands on vibration suppression while maintaining comparable size and performance to known sensors to ensure full compatibility with current consumer products.
[0020] The aforementioned MEMS gyroscopes also need to have high sensitivity accuracy. To this end, it is crucial to ensure that the interference between sensing axes (the so-called "inter-axis" interference) is reduced.
[0021] However, due to the design limitations mentioned above, the known gyroscope structures cannot always allow the desired performance to be achieved.
[0022] Therefore, it is necessary to overcome the limitations of known devices and meet the above requirements. Summary of the Invention
[0023] According to this solution, a microelectromechanical (MEMS) gyroscope is provided, specifically a three-axis MEMS gyroscope.
[0024] For example, a MEMS gyroscope includes a microelectromechanical structure having a main extension in a horizontal plane formed by a first horizontal axis and a second horizontal axis. The structure includes a first driving mass and a first sensing mass, the first driving mass being configured to perform translational driven movement along a second horizontal axis of the horizontal plane. The first sensing mass has an anchoring element centrally arranged relative to the first sensing mass and is elastically connected to the anchoring element. The first sensing mass is coupled to the first driving mass via an elastic coupling element and is configured to perform rotational movement within the horizontal plane about the anchoring element by the drive of the first driving mass, and to perform sensing movement about a rotation axis defined by the elastic arrangement outside the horizontal plane in response to a first angular velocity about the first horizontal axis. The rotation axis extends along the second horizontal axis parallel to the translational driven movement of the first driving mass.
[0025] The elastic coupling element may include a central portion that is straight along a second horizontal axis and is rigid to transmit translational drive movement of the first driving mass to the first sensing mass; and an end portion disposed at the distal end of the central portion and coupled to the first driving mass and the first sensing mass, respectively. The end portion may be elastic and yielding to allow rotation outside the horizontal plane of the first sensing mass.
[0026] The first sensing mass block may have an extension symmetrical about the first horizontal axis and the axis of rotation, and an elastic coupling element may be coupled to the first sensing mass block at a coupling point located at a non-zero distance between the first horizontal axis and the axis of rotation.
[0027] The central portion of the elastic coupling element may have a certain length along the second horizontal axis; and the end portion of the elastic coupling element may have a folded shape, a total extension length along the first horizontal axis, and the branches forming the folded shape having a certain thickness. The distance value can determine the detection sensitivity of the first sensing mass block, and the value of the total extension length of the central portion and the value of the thickness of the end portion can determine the frequency of sensing movement.
[0028] The first sensing mass block may have a central window, within which an anchoring element is arranged at a central position. Alternatively, an elastic arrangement may be placed within the central window, having a main extension along a second horizontal axis and defining a rotation axis.
[0029] The microelectromechanical system (MEMS) may have a first axis of symmetry and a second axis of symmetry extending along a first horizontal axis and a second horizontal axis, respectively. In addition to the first driving mass, the structure may further include a second driving mass to form a first pair of driving mass blocks arranged on the same side of the second axis of symmetry and aligned along the second horizontal axis; and a third and fourth driving mass blocks forming the second pair of driving mass blocks, which are symmetrically arranged with respect to the second axis of symmetry and aligned with the first pair of driving mass blocks along the second horizontal axis. In addition to a first sensing mass block representing a first pitch sensing mass block for sensing pitch angular velocity about the first horizontal axis, the structure may further include a second pitch sensing mass block, forming a pair of pitch sensing mass blocks arranged symmetrically with respect to the first axis of symmetry and located externally relative to all the first and second pairs of driving mass blocks. The first pitch sensing mass block can also be elastically coupled to the third drive mass block via a corresponding elastic coupling element (having features corresponding to the elastic coupling element), and the second pitch sensing mass block can be elastically coupled to both the second and fourth drive mass blocks via a corresponding elastic coupling element (having features corresponding to the elastic coupling element). The structure may include a first roll sensing mass block and a second roll sensing mass block for sensing roll angular velocity about a second horizontal axis, arranged opposite each other on opposite sides of a first axis of symmetry, and elastically connected to each other via an elastic coupling element centrally located at the second axis of symmetry. The first and second roll sensing mass blocks may be equivalent to all the drive mass blocks of the first and second pairs arranged internally, and the first roll sensing mass block can be elastically coupled to the first and third drive mass blocks via corresponding elastic coupling elements aligned along the first horizontal axis, and the second roll sensing mass block can be elastically coupled to the second and fourth drive mass blocks via corresponding elastic coupling elements aligned along the first horizontal axis. The structure may include a first pair of yaw sensing masses and a second pair of yaw sensing masses for sensing yaw angular velocity about a vertical axis orthogonal to the horizontal plane. These are arranged on the outer sides and coupled to a first pair of drive masses and a second pair of drive masses via corresponding elastic coupling elements. The pitch sensing mass, the first roll sensing mass, the second roll sensing mass, the first pair of yaw sensing masses, and the second pair of yaw sensing masses can be driven by all the drive masses of the first and second pairs in a common drive mode to perform corresponding sensing movements for detecting pitch, roll, and yaw angular velocities.
[0030] The first, second, third, and fourth drive mass blocks can be configured to perform translational movements along a second horizontal axis, with each pair of drive mass blocks moving in opposite phases. The translational movements of the first, second, third, and fourth drive mass blocks relative to a first axis of symmetry are also in opposite phases. The translational movements of the drive mass blocks can be configured such that the first and second roll sensing mass blocks rotate in opposite phases in the horizontal plane about an axis parallel to the vertical axis and passing through their respective centers; the first and second pairs of yaw sensing mass blocks move in opposite phases synchronously with the first, second, third, and fourth drive mass blocks along the second horizontal axis; and the pitch sensing mass block rotates in opposite phases about an axis parallel to the vertical axis and passing through its respective center.
[0031] The movement of the first roll sensing mass block, the second roll sensing mass block, the first pair of yaw sensing mass blocks, the second pair of yaw sensing mass blocks, and the pitch sensing mass block caused by the translational movement of the first driving mass block, the second driving mass block, the third driving mass block, and the fourth driving mass block can occur entirely within the horizontal plane.
[0032] The sensing movements of the first roll sensing mass block, the second roll sensing mass block, the first pair of yaw sensing mass blocks, the second pair of yaw sensing mass blocks, and the pitch sensing mass block can be independent of each other and have no mutual influence.
[0033] The first drive mass block, the second drive mass block, the third drive mass block, and the fourth drive mass block can operate as decoupling elements between the first roll sensing mass block, the second roll sensing mass block, the first pair of yaw sensing mass blocks, the second pair of yaw sensing mass blocks, and the pitch sensing mass block. The first roll sensing mass block, the second roll sensing mass block, the first pair of yaw sensing mass blocks, the second pair of yaw sensing mass blocks, and the pitch sensing mass block are connected to the first drive mass block without being connected to each other.
[0034] The pitch sensing mass can be configured to rotate in opposite phases out of the horizontal plane about a rotation axis defined by a corresponding elastic arrangement for coupling with a corresponding anchoring element, when there is a pitch angular velocity about a first horizontal axis and due to the Coriolis force.
[0035] The first roll sensing mass and the second roll sensing mass can be configured to rotate in opposite phases outside the horizontal plane about a corresponding rotation axis defined by a corresponding elastic coupling element when there is a roll angular velocity about a second horizontal axis and due to the Coriolis force.
[0036] The first pair of yaw sensing mass blocks and the second pair of yaw sensing mass blocks can be configured to translate in opposite phases along the first horizontal axis when there is a yaw angular velocity about the vertical axis and due to the Coriolis force.
[0037] Each of the first and second roll sensing mass blocks may be generally rectangular in the horizontal plane, extend along a second horizontal axis, and have a window in the middle. A corresponding roll anchor is arranged in the window and is coupled to the window by an elastic coupling arrangement that defines a rotation axis for sensing movement outside the horizontal plane.
[0038] The yaw sensing mass and the yaw sensing mass in the first pair and the second pair can be coupled to each other by corresponding elastic coupling structures that extend centrally along the second horizontal axis and thus through the first axis of symmetry. Each elastic coupling structure can define a central pivot type lever elastic element that is hinged at a central anchor and coupled at its end to a corresponding yaw sensing mass in the first or second pair of yaw sensing masses. Attached Figure Description
[0039] To better understand the invention, preferred embodiments thereof are now described purely by way of non-limiting examples and with reference to the accompanying drawings, in which: Figure 1A and Figure 1B A schematic plan view of a known microelectromechanical structure is shown with reference to the corresponding driving movement and the corresponding sensing movement, respectively. Figure 2A A schematic plan view of a portion of a microelectromechanical system, particularly a MEMS gyroscope, is shown with reference to the elastic coupling structure between the driving mass block and the sensing mass block. Figure 2B One aspect of this solution is shown. Figure 2A Enlarged planar view of the elastic coupling structure; Figure 3 A schematic plan view of the microelectromechanical structure of a three-axis MEMS gyroscope according to another aspect of this solution is shown; Figure 4 schematically shown Figure 3 The drive mode in the gyroscope; Figure 5 schematically shown Figure 3 Pitch sensing mode in the gyroscope; Figure 6 schematically shown Figure 3 The roll sensing mode in the gyroscope; and Figure 7 schematically shown Figure 3Yaw sensing mode in the gyroscope. Detailed Implementation
[0040] As described below, a first aspect of this solution provides an optimized elastic structure for achieving elastic coupling between a sensing mass and a corresponding driving mass in a MEMS gyroscope (particularly a triaxial MEMS gyroscope).
[0041] The elastic structure is configured to couple the translational drive movement of the driving mass block to the rotational movement of the sensing mass block in the horizontal plane (around the central anchor), thus allowing the sensing movement of rotation outside the same horizontal plane when the angular velocity to be detected is present.
[0042] Specifically, the elastic structure is configured such that the direction of the translational drive movement of the driving mass is parallel to the axis of rotation around which the sensing movement of the sensing mass performs the aforementioned rotation outside the horizontal plane revolves.
[0043] Figure 2A A portion of the microelectromechanical structure of a MEMS gyroscope, such as a triaxial MEMS gyroscope, is shown, which includes at least one driving mass 12 and at least one sensing mass 14.
[0044] In the example, sensing mass block 14 (as described above) Figure 2A (Only the first half is shown) It is a roughly rectangular shape that extends along the horizontal axis x of the horizontal plane xy, which coincides with the main extension plane of the first sensing mass block 14 (the extension of the sensing mass block 14 along the vertical axis z that is orthogonal to the horizontal plane xy is small and can be ignored compared to the main extension).
[0045] In particular, Figure 2A In the diagram, the half-length of the sensing mass block 14 along the horizontal axis x is labeled L.
[0046] The sensing mass 14 is centrally coupled to the anchoring element 16, which is integral with the substrate (not shown) arranged below the first sensing mass 14, and the microelectromechanical structure of the MEMS gyroscope is formed by the substrate (e.g., the anchoring element 16 is a vertical column extending along the aforementioned vertical axis z to the substrate below).
[0047] Specifically, the sensing mass block 14 has a central window 17, in which the anchoring element 16 is arranged, and the sensing mass block 14 is elastically connected to the same anchoring element 16 by an elastic arrangement 18, which has a main extension along the horizontal axis y of the horizontal plane xy and defines a rotation axis A for the sensing mass block 14 to rotate outside the horizontal plane xy.
[0048] In the example, drive mass block 12 (as described above) Figure 2AAlso shown only in its first half) is also generally rectangular and extends along the horizontal axis y.
[0049] In particular, the sensing mass 14 is elastically coupled to the driving mass 12 through a coupling elastic element 20.
[0050] The coupling elastic element 20 has a generally elongated extension, in the example along the horizontal axis y (i.e., parallel to the above-mentioned rotation axis A), and is interposed between the sensing mass 14 and the driving mass 12. In particular, it is coupled to the sensing mass 14 at the coupling point P, which is placed at a distance b measured along the horizontal axis x from the rotation axis A; thus, the relationship 0 < b < L is satisfied (obviously, the coupling point P can correspond to, for example, the center point of the actual coupling region between the above-mentioned coupling elastic element 20 and the sensing mass 14).
[0051] Specifically, as Figure 2B shown, according to an embodiment of the present solution, in the example, the coupling elastic element 20 includes a linearly elongated central portion 20a having a length Lr in the direction of the horizontal axis y, and this central portion 20a is rigid in the same direction to transmit the driving movement of the driving mass 12 to the sensing mass 14 (the driving movement occurring along the same extension direction of the coupling elastic element 2, and thus parallel to the rotation axis A).
[0052] The coupling elastic element 20 further includes end portions 20b, which are arranged at the distal ends of the above-mentioned central portion 20a and are respectively coupled to the driving mass 12 and the sensing mass 14.
[0053] These end portions 20b are elastic and deform with the movement outside the horizontal plane xy to allow the sensing mass 14 to rotate about the rotation axis A.
[0054] Specifically, in the Figure 2B shown embodiment, the end portions 20b are in a folded, bellows, or serpentine shape (alternating shorter portions linearly extending along the horizontal axis y and longer portions extending along the horizontal axis x, with the extension directions of the longer portions alternating in opposite directions), and its total extension along the horizontal axis x is denoted as Lf; the thicknesses of the branches forming the folded pattern are also generally the same and are denoted as w.
[0055] As discussed above, the configuration of the coupling elastic element 20 enables the translational driving movement of the driving mass 12 to be transmitted to the rotational movement of the sensing mass 14 in the horizontal plane xy (about the corresponding central anchor defined by the anchoring element 16) with a limited area occupation, thus allowing the sensing mass 14 to perform an out-of-plane sensing movement due to the Coriolis force when there is an angular velocity (for example, the pitch angular velocity about the horizontal axis x described in detail below).
[0056] In particular, as emphasized above, in this solution, the driving direction of the driving mass 12 is parallel to the rotation axis A around which the sensing mass 14 moves for sensing.
[0057] Furthermore, the configuration of the aforementioned coupling elastic element 20 makes it easy to adjust the sensitivity value when sensing angular velocity, simply by appropriately adjusting the distance b from the rotation axis A of the coupling point P using the sensing mass block 14.
[0058] In fact, the following relationship applies to the motion transmission between the driving mass block 12 (translational movement) and the sensing mass block 14 (rotational movement): where u_y indicates the displacement of the driving mass block 12 along the horizontal axis y under the aforementioned translational movement, and θ indicates the rotation angle of the sensing mass block 14 in the horizontal plane xy about the anchoring element 16.
[0059] Furthermore, by applying stiffness to the coupling elastic element 20, the resonant frequency value of the sensing mode can be easily adjusted without significantly affecting the driving mode.
[0060] In particular, the stiffness of the coupling mechanism can be adjusted by applying the values of the total extension length Lf and thickness w associated with the end portion 20b of the coupling elastic element 20, and the value of the length Lr applied to the central portion 20a of the same coupling elastic element 20.
[0061] For example, modifying the thickness w by 10% may result in a change of about 5% in the resonant frequency associated with sensing movement, while the change in the resonant frequency associated with driving movement is less than 1%.
[0062] refer to Figure 3 According to another aspect of this solution, a possible embodiment of the microelectromechanical structure of a three-axis MEMS gyroscope, indicated herein by 10, is now fully described. This microelectromechanical structure includes the aforementioned driving mass 12 and the aforementioned sensing mass 14 (in... Figure 3 In the dashed box, the part corresponding to the structure described in Figure 2 is highlighted.
[0063] As will be described in detail, this embodiment advantageously allows for reduced interference between sensing axes while minimizing area footprint, and achieves high performance in suppressing interfering vibrations.
[0064] The microelectromechanical structure 10 has a main extension in the horizontal plane xy (not shown, which is suspended above the substrate at a certain distance from the substrate along the vertical axis z), and a first axis of symmetry (or centerline axis) M1 and a second axis of symmetry (or centerline axis) M2 extending along the horizontal axis x and the horizontal axis y, respectively.
[0065] In addition to the aforementioned drive mass block 12 (represented here as the first drive mass block, indicated by D1), the microelectromechanical structure 10 also includes a second drive mass block D2, which together form a first pair of drive mass blocks D1 and D2, arranged on the same side of the second axis of symmetry M2 and aligned along the horizontal axis y.
[0066] In the illustrated embodiment, the first pair of driving mass blocks D1 and D2 are also coupled to the same first driving anchor 30 through corresponding folded or corrugated anchoring elastic elements 31. The first driving anchor 30 is integral with the substrate (not shown) and is centrally arranged at the first axis of symmetry M1.
[0067] The microelectromechanical structure 10 also includes a third drive mass block and a fourth drive mass block, indicated as D3 and D4, which form a second pair of drive mass blocks.
[0068] The second pair of driving mass blocks D3 and D4 are arranged on the second side of the second axis of symmetry M2, aligned along the horizontal axis y, in a manner that is symmetrical with respect to the second axis of symmetry M2 and the first pair of driving mass blocks D1 and D2.
[0069] In this case, the second pair of driving mass blocks D3, D4 are coupled to the same second driving anchor 32 through corresponding folded or corrugated anchor elastic elements 33. The second driving anchor 32 is integral with the substrate (not shown) and is centrally arranged at the first axis of symmetry M1 (again, in a completely symmetrical distribution relative to the first pair of driving mass blocks D1, D2).
[0070] In a manner not shown in detail herein, the first pair of driving mass blocks D1, D2 and the second pair of driving mass blocks D3, D4 may internally define windows for active driving electrodes, which are integral with the same mass blocks and interdigitally distributed with corresponding fixed driving electrodes arranged in the same windows; in a known manner, the interaction between the interdigital electrodes determines the aforementioned driving movement.
[0071] In addition to the aforementioned sensing mass 14 (which is configured here to sense pitch angular velocity and is therefore referred to as the first pitch sensing mass P1), the microelectromechanical structure 10 of the MEMS gyroscope also includes a second pitch sensing mass P2, which together form a pair of pitch sensing mass blocks P1 and P2.
[0072] Specifically, the pitch sensing masses P1 and P2 are arranged symmetrically with respect to the first axis of symmetry M1, are located outside (along the direction of the horizontal axis y) relative to the driving masses D1, D2, D3, and D4, and extend longitudinally along the horizontal axis x, thereby passing through the second axis of symmetry M2, and are symmetrical with respect to the second axis of symmetry M2.
[0073] The first pitch sensing mass P1 is elastically coupled to both the first driving mass D1 and the third driving mass D3 (i.e., driving mass blocks arranged on the same side relative to the first axis of symmetry M1) through a corresponding coupling elastic element 20. The configuration and operation of the coupling elastic element 20 are completely similar to those described above.
[0074] Similarly, the second pitch sensing mass P2 is elastically coupled to both the second drive mass D2 and the fourth drive mass D4 via a corresponding coupling elastic element 20, the configuration and operation of which are again exactly the same as described above.
[0075] The microelectromechanical structure 10 also includes a first roll sensing mass R1 and a second roll sensing mass R2, which are arranged symmetrically on opposite sides of the first axis of symmetry M1 and are elastically connected to each other by a coupling elastic element 35, which is centrally located at the second axis of symmetry M2 and whose stiffness allows the roll sensing masses R1 and R2 to move (as will be described in detail below) while keeping them constrained to each other in their movement.
[0076] The roll sensing mass blocks R1 and R2 are typically arranged at the center of the first pair of drive mass blocks D1 and D2 and the second pair of drive mass blocks D3 and D4.
[0077] Each roll sensing mass R1, R2 is generally rectangular in the horizontal plane xy, extending along the horizontal axis y in the example, and has a window at its center (not shown here for simplicity), which has a corresponding roll anchor 36 arranged therein. The roll sensing mass is coupled to the roll anchor 36 by an elastic coupling arrangement (not shown here for simplicity), which defines a rotation axis for sensing movement outside the horizontal plane xy (extending along the horizontal axis x in the example).
[0078] For example, such a flexible coupling arrangement can be provided as detailed in Italian patent application No. 102024000017707 entitled “Microelectromechanical Structure With Improved Mechanical Robustness” filed on July 30, 2024 by inventors Patrick FEDELI, Paola CARULLI, Luca Giuseppe FAORNI and Federico MORELLI (incorporated herein by reference).
[0079] Furthermore, the first roll sensing mass R1 is elastically coupled to the first drive mass D1 and the third drive mass D3 via corresponding elastic coupling elements 38, which extend from opposite sides of the first roll sensing mass R1 and are aligned along the horizontal axis x. Figure 3 As schematically shown, such a flexible coupling element 38 can be, for example, linear.
[0080] Similarly, the second roll sensing mass R2 is elastically coupled to the second drive mass D2 and the fourth drive mass D4 via corresponding elastic coupling elements 38, which extend approximately along the horizontal axis x from opposite sides of the second roll sensing mass R2 (e.g., they can be linear).
[0081] Below the roll sensing mass blocks R1 and R2 (in a manner not shown here), corresponding fixed electrodes (or stator electrodes) are arranged, which are capacitively coupled to the corresponding roll sensing mass blocks R1 and R2 and placed above the substrate (in order to provide a differential sensing scheme of known type, which is not described in detail herein).
[0082] The microelectromechanical structure 10 of the MEMS gyroscope also includes a first pair of yaw sensing mass blocks Y1, Y2 and a second pair of yaw sensing mass blocks Y3, Y4. In the example, each yaw sensing mass block is approximately rectangular in the horizontal plane and extends along the horizontal axis y.
[0083] Each of the first pair of yaw sensing mass blocks Y1, Y2 is elastically coupled to the corresponding drive mass block of the first pair of drive mass blocks D1, D2 via a corresponding coupling elastic element 39 (in the example, the number of each mass block is equal to two, and they are inserted between the end portions of the coupled drive mass block and the yaw sensing mass block).
[0084] Similarly, each of the second pair of yaw sensing mass blocks Y3 and Y4 is elastically coupled to the corresponding drive mass block in the second pair of drive mass blocks D3 and D4 via a corresponding coupling elastic element 39.
[0085] Furthermore, the yaw sensing mass blocks in the first pair of yaw sensing mass blocks Y1 and Y2, and the yaw sensing mass blocks in the second pair of yaw sensing mass blocks Y3 and Y4, are coupled to each other through corresponding elastic coupling structures 40. These elastic coupling structures 40 extend centrally along the horizontal axis y, thereby passing through the first axis of symmetry M1.
[0086] In detail, each elastic coupling structure 40 defines a central pivot type lever elastic element that is hinged to the substrate via a central anchor 42 and coupled at its end to a corresponding yaw sensing mass block forming a first pair or a second pair.
[0087] For the sake of simplicity, the aforementioned yaw sensing mass blocks Y1, Y2, Y3, and Y4 have internal windows for yaw motion sensing electrodes. These yaw motion sensing electrodes are integrated with the same yaw sensing mass blocks and are alternately distributed with corresponding yaw fixed or stator sensing electrodes to define a differential sensing scheme.
[0088] The operation of the microelectromechanical structure 10 of the MEMS gyroscope is now described, which is used to sense the pitch angular velocity Ωp about the horizontal axis x, the roll angular velocity Ωr about the horizontal axis y, and the yaw angular velocity Ωy about the vertical axis z.
[0089] like Figure 4 Schematic illustration shows that the driven movement involves driving the drive masses D1, D2, D3, and D4 (through appropriate biasing of the active drive electrodes and corresponding fixed drive electrodes) to perform translational movements along the horizontal axis y (inverse phase for each pair). Furthermore, the movements of each pair of drive masses symmetrically with respect to the first axis of symmetry M1 (i.e., the movements of drive masses D1, D3 and D2, D4) are also inverse phase.
[0090] As mentioned above Figure 4 As emphasized by the arrows, due to the elastic coupling described above, the movement of the driving mass blocks D1, D2, D3, and D4 causes a corresponding movement of the sensing mass block.
[0091] Specifically, the roll sensing mass blocks R1 and R2 are driven to rotate in opposite phases in the horizontal plane xy around an axis parallel to the vertical axis z and passing through the center of the corresponding roll anchor 36.
[0092] Furthermore, the yaw sensing masses Y1, Y2, Y3, and Y4 are driven by the associated driving masses D1, D2, D3, and D4 in an overall manner to move in the same translational motion along the horizontal axis y in opposite phases.
[0093] Due to the action of the coupling elastic element 20 (whose operation is described in detail above), the movement of the driving mass blocks D1, D2, D3, and D4 will also cause the pitch sensing mass blocks P1 and P2 to rotate in opposite phase around the axis parallel to the vertical axis z and passing through the center of the corresponding anchoring element 16.
[0094] Therefore, the aforementioned driving movement occurs entirely within the horizontal xy plane and does not affect other components of the MEMS gyroscope's microelectromechanical structure 10.
[0095] like Figure 5Schematably shown (corresponding to a given operating moment), when there is a pitch angular velocity Ωp about the horizontal axis x, the motion of the microelectromechanical structure 10 involves the pitch sensing masses P1 and P2 rotating in opposite phases about a rotation axis A outside the horizontal plane xy, which is parallel to the horizontal axis y and is provided by a corresponding elastic arrangement 18 (in Figure 2A (as shown in the image) is limited.
[0096] Essentially, such as Figure 5 Schematic representation: Due to the Coriolis force, pitch sensing masses P1 and P2 rotate in opposite phases outside the horizontal plane xy, thereby determining the movement away from / towards the corresponding pitch stator electrode (not shown here) along the vertical axis z, and ultimately determining the capacitance change that can be detected by a differential sensing scheme.
[0097] It should be emphasized that under these operating conditions, the other components of the MEMS gyroscope's microelectromechanical structure 10 (especially the mass block and associated elastic element used to sense roll and yaw angular velocities) are essentially unaffected, or under no circumstances interfere with the operation mode of pitch angular velocity detection.
[0098] like Figure 6 As schematically shown (corresponding to a given operating moment), when there is a roll angular velocity Ωr about the horizontal axis y, the motion of the microelectromechanical structure 10 involves the roll sensing masses R1, R2 rotating in opposite phase about a rotation axis defined by the corresponding elastic coupling element outside the horizontal plane xy (this rotation can again be detected by a differential sensing scheme and corresponding sensing electrodes, which are not shown here).
[0099] Moreover, under these conditions, other components of the microelectromechanical system 10 (especially those used to detect pitch and yaw rates) are essentially unaffected by the operating conditions or do not interfere with roll sensing movement under any circumstances.
[0100] like Figure 7 As schematically shown, when there is a yaw angular velocity Ωy about the vertical axis z, the sensing motion of the microelectromechanical structure 10 of the MEMS gyroscope involves the opposite phase displacement of each pair of yaw sensing masses Y1, Y2, Y3, Y4 along the horizontal axis x (as indicated by the arrows). Furthermore, the movements of each pair of yaw sensing masses (i.e., yaw sensing masses Y1, Y3 and Y2, Y4) that are symmetrical to each other with respect to the second axis of symmetry M2 are also opposite phase.
[0101] This movement also causes the corresponding central anchor 42 of the lever elastic element around the elastic coupling structure 40 to rotate in the horizontal plane xy, which couples the yaw sensing mass blocks that are symmetrical about the horizontal axis x to each other.
[0102] The movement of the yaw active electrode (not shown here) relative to the alternating yaw stator electrodes along the horizontal axis x, and the resulting capacitance change, occurs, which can be sensed by a differential scheme.
[0103] Furthermore, under these operating conditions, the other components of the microelectromechanical system 10 (particularly those used to sense pitch and roll angular velocities) remain essentially stationary or, under no circumstances, interfere with the sensing of yaw movement.
[0104] Advantageously, the sensing movements of the yaw sensing mass, roll sensing mass, and pitch sensing mass are therefore completely independent of each other and do not affect each other in any way. This effectively makes the interference between the sensing axes of the MEMS gyroscope (so-called inter-axis interference) essentially zero, or negligible in any case.
[0105] Specifically, the drive mass blocks D1-D4 essentially act as decoupling elements between the sensing mass blocks. In fact, all sensing mass blocks are only connected to the drive mass blocks D1-D4, with virtually no connection to each other (and no mutual interference), and are driven by the same drive mass blocks D1-D4 in a single drive mode.
[0106] Furthermore, the differential sensing scheme employed allows for the elimination of the effects associated with both linear and angular disturbance vibrations.
[0107] Specifically, all operating modes (i.e., drive mode and sensing mode) are not excited by linear acceleration or rotational acceleration; furthermore, over a wide frequency range (e.g., up to 40 kHz), no parasitic modes are excited by linear acceleration.
[0108] In this regard, reference can also be made to patent application EP24177019.7 filed by the same applicant on May 21, 2024, which describes a differential sensing scheme for a three-axis gyroscope that uses the same movement scheme for driving the mass and for sensing the mass to have substantially the same disturbance insensitivity characteristics.
[0109] The advantages of the proposed solution are clearly evident from the above description.
[0110] In all cases, it must be emphasized again that the described solution provides an optimized elastic coupling element for MEMS gyroscopes, which allows translational motion to be converted into rotational motion, with the following characteristics: the direction of movement of the driving mass is parallel to the axis of rotation around which the sensing motion (of the sensing mass associated with the same driving mass) is directed; the sensitivity can be modified by simply shifting the coupling point between the driving mass and the sensing mass; and the frequency of the sensing mode can be easily adjusted by acting on the geometric features of the elastic coupling element with limited effect on the driving mode.
[0111] Furthermore, the described solution allows for the provision of a three-axis gyroscope in which: (at a single frequency) a single drive mode is used because all sensing mass blocks are directly coupled to the same drive mass block (without coupling to each other); interference between sensing axes is essentially zero because sensing movements associated with each sensing axis are completely independent of the other sensing axes; and both linear vibrations and angular vibrations that cause interference are suppressed in a substantially complete manner.
[0112] Due to the aforementioned characteristics, the coupling solution allows for higher sensing accuracy, and thus enables more efficient and faster calibration operations.
[0113] Furthermore, the three-axis gyroscope has a compact architecture and requires no substantial modification to the manufacturing process, especially compared to standard solutions, it requires no additional machining steps or different treatments.
[0114] Finally, it should be noted that various modifications and variations can be made to the content described and shown herein without departing from the scope of protection of the invention as defined by the appended claims.
[0115] In particular, the elastic coupling solution described above for transmitting the translational motion of the driving mass to the rotational motion of the associated sensing mass can also find advantageous applications in the sensing structures of single-axis or dual-axis MEMS gyroscopes.
Claims
1. A MEMS gyroscope including a microelectromechanical structure (MEMS), the MEMS having a main extension in a horizontal plane formed by a first horizontal axis and a second horizontal axis, and the MEMS gyroscope comprising: The first driving mass block is configured to perform translational driving movement along the second horizontal axis of the horizontal plane; as well as A first sensing mass block has an anchoring element, the anchoring element being centrally arranged relative to the first sensing mass block, and the first sensing mass block being elastically connected to the anchoring element. The first sensing mass block is coupled to the first driving mass block via an elastic coupling element and is configured as follows: The anchoring element performs a rotational movement within the horizontal plane, wherein the rotational movement is driven by the first driving mass block; and Sensing movement that performs rotation outside the horizontal plane in response to a first angular velocity about the first horizontal axis and about a rotation axis defined by the elastic arrangement; The rotation axis extends along the second horizontal axis, which is parallel to the translational drive movement of the first drive mass.
2. The MEMS gyroscope according to claim 1, wherein the elastic coupling element comprises: The central portion is straight along the direction of the second horizontal axis and is rigid so as to transmit the translational drive movement of the first driving mass block to the first sensing mass block. as well as The end portion is located at the far end of the central portion and is coupled to the first driving mass block and the first sensing mass block, respectively. The end portion is elastic and conformable to deformation to allow rotation outside the horizontal plane of the first sensing mass block.
3. The MEMS gyroscope of claim 2, wherein the first sensing mass has an extension extending along the first horizontal axis and symmetrical with respect to the rotation axis; and wherein the elastic coupling element is coupled to the first sensing mass at a coupling point arranged along the first horizontal axis at a non-zero distance from the rotation axis.
4. The MEMS gyroscope of claim 3, wherein the central portion of the elastic coupling element has a certain length along the second horizontal axis, and the end portion of the elastic coupling element has a folded shape, a total extension along the first horizontal axis, and a certain thickness of the branches forming the folded shape; wherein the value of the non-zero distance determines the detection sensitivity of the first sensing mass block, and the value of the length of the central portion, the value of the length of the total extension, and the value of the thickness of the end portion determine the frequency of the sensing movement.
5. The MEMS gyroscope of claim 1, wherein the first sensing mass has a central window, the anchoring element is arranged at a central position within the central window; the elastic arrangement is also arranged within the central window and has a main extension along the second horizontal axis and defines the rotation axis.
6. The MEMS gyroscope of claim 1, wherein the microelectromechanical structure has a first axis of symmetry and a second axis of symmetry extending along the first horizontal axis and the second horizontal axis, respectively, and the microelectromechanical structure comprises: In addition to the first driving mass block, a second driving mass block is formed to create a first pair of driving mass blocks, which are arranged on the same side of the second axis of symmetry and aligned along the second horizontal axis. as well as The third and fourth driving mass blocks form a second pair of driving mass blocks, which are arranged symmetrically with respect to the second axis of symmetry as the first pair of driving mass blocks and are aligned along the second horizontal axis. The first and second pitch sensing mass blocks, representing the first pitch sensing mass block, form a pair of pitch sensing mass blocks. The first pitch sensing mass block is used to sense the pitch angular velocity about the first horizontal axis. The pair of pitch sensing mass blocks are arranged symmetrically with respect to the first axis of symmetry, and all the drive mass blocks relative to the first pair of drive mass blocks and the second pair of drive mass blocks are located on the outside. The first pitch sensing mass block is also elastically coupled to the third drive mass block through a corresponding elastic coupling element having features corresponding to the elastic coupling element, and the second pitch sensing mass block is elastically coupled to both the second drive mass block and the fourth drive mass block through a corresponding elastic coupling element having features corresponding to the elastic coupling element. A first roll sensing mass block and a second roll sensing mass block, for sensing roll angular velocity about the second horizontal axis, are symmetrically arranged on opposite sides of the first axis of symmetry and elastically connected to each other by an elastic coupling element centrally arranged at the second axis of symmetry. The first roll sensing mass block and the second roll sensing mass block are arranged internally relative to all the drive mass blocks of the first pair of drive mass blocks and the second pair of drive mass blocks, wherein the first roll sensing mass block is elastically coupled to the first drive mass block and the third drive mass block by a corresponding elastic coupling element aligned along the first horizontal axis, and the second roll sensing mass block is elastically coupled to the second drive mass block and the fourth drive mass block by a corresponding elastic coupling element aligned along the first horizontal axis. The first pair of yaw sensing mass blocks and the second pair of yaw sensing mass blocks are configured to sense the yaw angular velocity about a vertical axis orthogonal to the horizontal plane, are arranged outside the first pair of driving mass blocks and the second pair of driving mass blocks, and are coupled to the first pair of driving mass blocks and the second pair of driving mass blocks through corresponding elastic coupling elements. The pitch sensing mass block, the first roll sensing mass block, the second roll sensing mass block, the first pair of yaw sensing mass blocks, and the second pair of yaw sensing mass blocks are driven by all the drive mass blocks of the first pair of drive mass blocks and the second pair of drive mass blocks in a common drive mode to perform the corresponding sensing movements for detecting the pitch, roll, and yaw angular velocities.
7. The MEMS gyroscope according to claim 6, The first, second, third, and fourth driving mass blocks are configured to perform translational movements along the second horizontal axis. The translational movements of each pair of driving mass blocks are in opposite phases, and the translational movements of the first, second, third, and fourth driving mass blocks, which are symmetrical about each other with respect to the first axis of symmetry, are also in opposite phases. The translational movement of the driving mass block is configured as follows: The first roll sensing mass block and the second roll sensing mass block are rotated in opposite phases in the horizontal plane about an axis parallel to the vertical axis and passing through the respective centers of the first roll sensing mass block and the second roll sensing mass block. The first pair of yaw sensing mass blocks and the second pair of yaw sensing mass blocks are moved in opposite phase along the second horizontal axis in a manner that integrates them with the first, second, third, and fourth drive mass blocks; and The pitch sensing mass is rotated in the opposite phase about an axis parallel to the vertical axis and passing through the corresponding center of the pitch sensing mass.
8. The MEMS gyroscope according to claim 7, wherein the movement of the first roll sensing mass block, the second roll sensing mass block, the first pair of yaw sensing mass blocks, the second pair of yaw sensing mass blocks, and the pitch sensing mass block caused by the translational movement of the first driving mass block, the second driving mass block, the third driving mass block, and the fourth driving mass block occurs entirely within the horizontal plane.
9. The MEMS gyroscope of claim 7, wherein the sensing movements of the first roll sensing mass block, the second roll sensing mass block, the first pair of yaw sensing mass blocks, the second pair of yaw sensing mass blocks, and the pitch sensing mass block are independent of each other and do not affect each other.
10. The MEMS gyroscope according to claim 7, wherein the first driving mass block, the second driving mass block, the third driving mass block, and the fourth driving mass block serve as decoupling elements between the first roll sensing mass block, the second roll sensing mass block, the first pair of yaw sensing mass blocks, the second pair of yaw sensing mass blocks, and the pitch sensing mass block, and wherein the first roll sensing mass block, the second roll sensing mass block, the first pair of yaw sensing mass blocks, the second pair of yaw sensing mass blocks, and the pitch sensing mass block are all connected to the first driving mass block when they are not connected to each other.
11. The MEMS gyroscope of claim 7, wherein the pitch sensing mass is configured to perform opposite rotational movements outside the horizontal plane, in the presence of the pitch angular velocity about the first horizontal axis and due to the Coriolis force, about the respective rotation axis defined by the respective elastic arrangement for coupling with the respective anchoring element.
12. The MEMS gyroscope of claim 7, wherein the first roll sensing mass and the second roll sensing mass are configured to perform counter-rotation outside the horizontal plane about a corresponding rotation axis defined by a corresponding elastic coupling element when the roll angular velocity about the second horizontal axis is present and due to the Coriolis force.
13. The MEMS gyroscope of claim 7, wherein the first pair of yaw sensing masses and the second pair of yaw sensing masses are configured to perform antiphase translational movement along the first horizontal axis when there is a yaw angular velocity about the vertical axis and due to the Coriolis force.
14. The MEMS gyroscope of claim 6, wherein each of the first roll sensing mass and the second roll sensing mass is generally rectangular in the horizontal plane, extends along the second horizontal axis, and has a window at its center, a corresponding roll anchor is arranged within the window, and each roll sensing mass is coupled to the corresponding roll anchor by an elastic coupling arrangement defining a rotation axis for the sensing movement outside the horizontal plane.
15. The MEMS gyroscope according to claim 6, The yaw sensing mass block and the first pair of yaw sensing mass blocks, as well as the yaw sensing mass block in the second pair of yaw sensing mass blocks, are coupled to each other by corresponding elastic coupling structures; the corresponding elastic coupling structures extend centrally along the second horizontal axis, thereby passing through the first axis of symmetry; and Each elastic coupling structure defines a central pivot type lever elastic element, which is hinged at a central anchor and coupled at its end to a corresponding yaw sensing mass in the first pair of yaw sensing mass blocks or the second pair of yaw sensing mass blocks.
16. A method of operating a MEMS gyroscope including a microelectromechanical structure (MEMS), the MEMS having a first driving mass, a second driving mass, a third driving mass, and a fourth driving mass, a first pitch sensing mass and a second pitch sensing mass, a first roll sensing mass and a second roll sensing mass, and a first pair of yaw sensing masses and a second pair of yaw sensing masses, the method comprising: The first driving mass block, the second driving mass block, the third driving mass block, and the fourth driving mass block are driven to perform translational movements along the second horizontal axis. The translational movements of each pair of driving mass blocks are in opposite phases, and the translational movements of the first driving mass block, the second driving mass block, the third driving mass block, and the fourth driving mass block, which are symmetrical to each other with respect to the first axis of symmetry, are also in opposite phases. Due to the translational movement of the first driving mass block, the second driving mass block, the third driving mass block, and the fourth driving mass block, the following results are achieved: The first roll sensing mass block and the second roll sensing mass block rotate in opposite phases in the horizontal plane around corresponding axes parallel to the vertical axis; The first pair of yaw sensing mass blocks and the second pair of yaw sensing mass blocks move in opposite phases along the second horizontal axis; and The first pitch sensing mass block and the second pitch sensing mass block rotate in opposite phases about corresponding axes parallel to the vertical axis; The pitch angular velocity about the first horizontal axis is detected by sensing the rotational movement of the first pitch sensing mass block and the second pitch sensing mass block about their respective rotation axes parallel to the second horizontal axis outside the horizontal plane. By sensing the rotational movement of the first roll sensing mass and the second roll sensing mass outside the horizontal plane, the roll angular velocity about the second horizontal axis is detected; and The yaw angular velocity about the vertical axis is detected by sensing the displacement of the first pair of yaw sensing mass blocks and the second pair of yaw sensing mass blocks along the first horizontal axis.
17. The method of claim 16, wherein driving the first driving mass block, the second driving mass block, the third driving mass block, and the fourth driving mass block comprises applying an electrical signal to a movable driving electrode, the movable driving electrode being integral with the driving mass block and interdigitated with a corresponding fixed driving electrode arranged within a window of the driving mass block.
18. The method of claim 16, wherein detecting the pitch angular velocity comprises using a differential sensing scheme to capacitively sense the movement of the first pitch sensing mass and the second pitch sensing mass away from and toward the corresponding pitch stator electrodes.
19. The method of claim 16, wherein detecting the yaw rate comprises using a differential sensing scheme to capacitively sense the movement of a yaw activity sensing electrode relative to alternating yaw stator sensing electrodes, the yaw activity sensing electrode being integral with the first pair of yaw sensing mass blocks and the second pair of yaw sensing mass blocks.
20. The method of claim 16, wherein the translational movements of the first drive mass, the second drive mass, the third drive mass, and the fourth drive mass, and the resulting movements of the first pitch sensing mass and the second pitch sensing mass, the first roll sensing mass and the second roll sensing mass, the first pair of yaw sensing mass and the second pair of yaw sensing mass, occur entirely within the horizontal plane, and wherein the sensing movements for detecting the pitch angular velocity, the roll angular velocity, and the yaw angular velocity are independent of each other and do not affect each other.