A method for suppressing quadrature error of ring micro electro mechanical gyroscope

Abstract

The application discloses a kind of annular micro electro mechanical gyroscope orthogonal error suppression methods, comprising: in the driving direction of gyroscope, respectively to two pairs of adjacent driving electrodes to generate driving force by applying driving voltage, and the direction of the resultant force of two driving forces is consistent with the direction of the main stiffness axis of gyroscope;In the detection direction of gyroscope, the electrical signal generated by two pairs of adjacent detection electrodes is superimposed after passing through amplification circuit, and the gain of two described amplification circuits is adjusted to realize orthogonal error suppression.The application is applied to the field of micro electro mechanical gyroscope, and is suitable for various driving forms of annular micro electro mechanical gyroscope, especially provides a kind of new orthogonal error suppression scheme for annular micro electro mechanical gyroscope of non-capacitive structure.

Description

Technical Field

[0001] This invention relates to the field of microelectromechanical systems (MEMS) technology, specifically a method for suppressing orthogonal errors in a ring-shaped MEMS gyroscope. Background Technology

[0002] A gyroscope is a sensor that measures the rotational motion of a carrier relative to inertial space. It is a core component in motion measurement, inertial navigation, guidance and control, and has significant application value in high-end industrial equipment such as aerospace and intelligent robots. Microelectromechanical gyroscopes (MEMS) emerged in the 1980s and are characterized by their small size, low power consumption, mass production capability, and ease of integration. They align with the development trend of product miniaturization, integration, and informatization, and have broad application prospects, making them a focus of attention.

[0003] The resonant structure of a ring-type microelectromechanical gyroscope (MEMS) is a two-dimensional planar symmetrical structure, possessing good machining robustness and resistance to shock and vibration. It also exhibits high mechanical sensitivity and measurement accuracy, representing a promising development direction for MEMS gyroscopes. However, due to factors such as actual machining errors and material defects, a certain frequency split exists between the two operating modes of the ring-type MEMS gyroscope, and the orientation of the principal stiffness axes corresponding to the two operating modes is inconsistent with the direction of the gyroscope electrodes, resulting in severe orthogonal errors. Although the orthogonal error is 90° out of phase with the useful signal and can be processed through circuit techniques such as phase demodulation, its presence affects the amplification effect of the preamplifier circuit. Excessive orthogonal errors not only saturate the preamplifier but also prevent the useful signal from being effectively amplified, leading to unstable signal output and making it difficult for the detection circuit to extract the useful signal, thus affecting the performance and accuracy of the gyroscope. Therefore, eliminating or suppressing orthogonal errors is of great significance for improving the performance of MEMS gyroscopes.

[0004] For common capacitive ring-type MEMS gyroscopes, the electrodes are separate from the gyroscope's moving parts (resonant structure). A voltage can be directly applied to the electrodes at a specific orientation to deflect the stiffness axis, aligning the gyroscope's principal stiffness axis with the gyroscope's reference coordinate system (determined by the actual electrode positions), thereby eliminating or suppressing orthogonality errors. However, for ring-type MEMS gyroscopes with other actuation methods such as piezoelectric and electromagnetic induction, the electrodes are typically attached to the interior or surface of the gyroscope's resonant structure, making it impossible to eliminate or suppress orthogonality errors using the aforementioned method. Therefore, a more universal orthogonality error suppression method needs to be developed to achieve orthogonality error suppression for ring-type MEMS gyroscopes with various actuation methods, including piezoelectric, electromagnetic, and capacitive types. Summary of the Invention

[0005] To address the shortcomings of the prior art, this invention provides a method for suppressing orthogonal errors in ring microelectromechanical gyroscopes, applicable to the suppression of orthogonal errors in ring microelectromechanical gyroscopes including piezoelectric, inductive, and capacitive drive types.

[0006] To achieve the above objectives, the present invention provides a method for suppressing orthogonal errors in a ring-shaped microelectromechanical gyroscope. The ring-shaped microelectromechanical gyroscope has a pair of adjacent and independent driving electrodes in the gyroscope driving direction and a pair of adjacent and independent detection electrodes in the gyroscope detection direction. The orthogonal error suppression method includes:

[0007] In the gyroscope driving direction, driving voltages are applied to two adjacent driving electrodes to generate driving force, and the resultant force of the two driving forces is aligned with the direction of the gyroscope's principal stiffness axis.

[0008] In the gyroscope detection direction, the electrical signals generated by two adjacent detection electrodes are amplified by two independent, adjustable-gain amplifier circuits and then superimposed. By adjusting the amplification factor of the two amplifier circuits, orthogonal error suppression is achieved.

[0009] In one embodiment, the driving voltage applied to two pairs of adjacent driving electrodes is a sinusoidal signal that is in phase and at the same frequency.

[0010] In one embodiment, the direction of the resultant force of the two driving forces is aligned with the direction of the gyroscope's principal stiffness axis, specifically as follows:

[0011] The amplitude of the driving voltage applied to the two driving electrodes can be changed individually or by choosing one of them to change the magnitude and direction of the resultant force of the two driving forces, so that the direction of the resultant force of the two driving forces is consistent with the direction of the principal stiffness axis of the gyroscope.

[0012] In one embodiment, the orthogonal error suppression is achieved by adjusting the amplification factor of the two amplifier circuits, specifically as follows:

[0013] The ratio of the amplification factors of the two amplifier circuits is adjusted to be equal to the ratio of the amplitudes of the driving voltages applied to the two pairs of driving electrodes, thereby achieving quadrature error suppression.

[0014] In one embodiment, the orthogonal error suppression method specifically includes the following steps:

[0015] Step 1: Keep the top stationary;

[0016] Step 2: In the gyroscope driving direction, drive voltages u1(t) and u2(t) are applied to two adjacent drive electrodes respectively to make the gyroscope oscillate, wherein u1(t) and u2(t) are in phase and have the same frequency;

[0017] Step 3: Connect two pairs of adjacent detection electrodes in the gyroscope detection direction to two adjustable gain amplifier circuits, and make K1 / K2≡u1 / u2, where K1 and K2 are the amplification factors of the two amplifier circuits, and u1 and u2 are the amplitudes of the driving voltages u1(t) and u2(t), respectively.

[0018] Step 4: Adjust the amplitudes of u1(t) and u2(t) separately or by choice until the output signal after the amplification and superposition of the two adjacent detection electrodes is 0, thus achieving orthogonal error suppression.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects:

[0020] This invention separates the driving electrode and detection electrode of a ring microelectromechanical gyroscope into two independent but adjacent electrodes. Different driving voltages are applied to the two adjacent driving electrodes, and the two adjacent detection electrodes are connected to two adjustable-gain amplifier circuits, maintaining the ratio of the amplification factors constant equal to the ratio of the driving voltages. Orthogonal error suppression is achieved by adjusting the driving voltages of the two driving electrodes. This method is applicable to ring microelectromechanical gyroscopes with various driving forms, eliminating the need to separate the gyroscope's electrodes from the resonant structure. It provides a novel orthogonal error suppression scheme, particularly for non-capacitive ring microelectromechanical gyroscopes. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0022] Figure 1 This is a plan view of the resonant structure of the ring-shaped microelectromechanical gyroscope in an embodiment of the present invention;

[0023] Figure 2 This is a cross-sectional schematic diagram of the overall structure of the ring-shaped microelectromechanical gyroscope in an embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the working modes of the ring microelectromechanical gyroscope in an embodiment of the present invention, wherein: (a) is a schematic diagram of the driving mode, and (b) is a schematic diagram of the detection mode;

[0025] Figure 4 This is a schematic diagram of the system structure for orthogonal error suppression of the ring microelectromechanical gyroscope in an embodiment of the present invention;

[0026] Figure 5This is a schematic diagram showing the stiffness of the ring microelectromechanical gyroscope resonant structure after normalization with respect to mass in an embodiment of the present invention.

[0027] Figure 6 This is a flowchart of the orthogonal error suppression method for a ring-shaped microelectromechanical gyroscope in an embodiment of the present invention.

[0028] Reference numerals: 1. Resonant ring; 2. Metal electrode; 3. Support beam; 4. Anchor point area; 5. Permanent magnet; 6. Magnetic conductive component.

[0029] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0032] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0033] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0034] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0035] This embodiment discloses a method for suppressing the orthogonal error of a ring microelectromechanical gyroscope, which is applicable to the orthogonal error suppression of ring microelectromechanical gyroscopes including various driving methods such as piezoelectric, inductive and capacitive, especially ring microelectromechanical gyroscopes with other driving methods such as piezoelectric and electromagnetic induction, in which the electrodes are attached to the inside or surface of the gyroscope resonant structure.

[0036] The orthogonal error suppression method in this embodiment is based on the premise that there are at least two adjacent and independent driving electrodes and at least two adjacent and independent detection electrodes on the resonant structure of the ring microelectromechanical gyroscope. To ensure the symmetry of the ring microelectromechanical gyroscope, the electrodes of the gyroscope are generally arranged at equal intervals along the circumference of the resonant structure, and the total number of electrodes is 4N×M, where N is the number of antinodes of the gyroscope's operating mode, and M is the number of adjacent and independent driving electrodes or adjacent and independent detection electrodes, and M is not less than 2.

[0037] The orthogonal error suppression method in this embodiment mainly includes:

[0038] On the one hand, in the gyroscope driving direction, driving voltages are applied to two pairs of adjacent driving electrodes to generate driving force. The two pairs of adjacent driving electrodes are symmetrical along the gyroscope driving direction. The resultant force of the driving force generated by the two pairs of adjacent driving electrodes always passes through the center of the resonant ring. The amplitude of the driving voltage applied to the two pairs of driving electrodes is changed, either individually or by one of them, to change the magnitude and direction of the resultant force of the two driving forces, so that the direction of the resultant force of the two driving forces is consistent with the direction of the principal stiffness axis of the gyroscope.

[0039] On the other hand, in the gyroscope detection direction, two pairs of adjacent and symmetrical detection electrodes are connected to two independent, adjustable-gain amplifier circuits. The electrical signals generated by the two pairs of adjacent detection electrodes are superimposed after passing through the amplifier circuits. By adjusting the amplification gain of the two pairs of adjacent electrodes, orthogonal error suppression is achieved.

[0040] by Figure 1 , Figure 2Taking the toroidal microelectromechanical gyroscope as an example, 16 independent metal electrodes 2 are evenly spaced along the circumference of the resonant ring 1. These metal electrodes 2 can be led out to the anchor point region 4 of the resonant structure via the support beam 3 for connection to an external circuit. The resonant ring 1 is located within the magnetic field constructed by the permanent magnet 5 and the magnetically conductive component 6. The magnetic field near the resonant ring 1 is perpendicular to the plane of the resonant ring 1. When current flows through the metal electrodes 2, they are subjected to an Ampere force, forming a driving force that causes the gyroscope's resonant structure to move. The line of action of this driving force passes through the center of the resonant ring 1. (Reference) Figure 3 The ring-shaped microelectromechanical gyroscope operates in a pair of degenerate modes, referred to as the first mode (driving mode) and the second mode (detection mode); the number of antinodes in the operating mode is N=2. When the first mode is in a state of vibration, the gyroscope rotates, which excites the second mode of the gyroscope under the action of the Coriolis force. The input angular velocity information can be obtained by solving the vibration signal of the second mode.

[0041] Due to manufacturing errors and material defects, toroidal microelectromechanical gyroscopes (MEMS) often exhibit uneven stiffness distribution, leading to vibration coupling errors. The phase difference between the vibration coupling signal caused by stiffness asymmetry and the vibration signal excited by the Coriolis force is 90°, known as orthogonality error. Uneven stiffness distribution is usually the main cause of orthogonality errors in MEMS gyroscopes.

[0042] refer to Figure 4 In the direction of gyroscope drive (i.e. Figure 4 Voltages u1(t) and u2(t) are applied to the two driving electrodes (x-axis) respectively, generating driving forces F1 and F2 respectively; in the gyroscope detection direction (i.e., Figure 4 The two detection electrodes (on the y-axis) are connected to amplifier circuits K1 and K2 respectively. The induced electromotive force signals e1(t) and e2(t) generated by the detection electrodes are amplified by K1 and K2 times respectively and then superimposed on each other and connected to the measurement and control circuit. The superimposed output signal is e(t) = K1e1(t) + K2e2(t).

[0043] like Figure 5 As shown, the stiffness of the ring microelectromechanical gyroscope resonant structure is normalized with respect to its mass. The non-uniformity of the normalized stiffness results in the existence of an orthogonal principal stiffness axis x. ω -Oy ω It has an angular deviation θ from the ideal reference coordinate system xOy. ω Furthermore, the two canonical resonant frequencies ω1 and ω2 on the principal stiffness axis differ. The deflection angle θ of the stiffness axis in the normalized coordinate system... ω The relationship between the stiffness axis deflection angle θ and the actual physical space is θ ω =Nθ. On the principal rigid axis x ω -Oy ωThe differential equations of the second-order system of the ring microelectromechanical gyroscope are as follows:

[0044]

[0045] Where τ is the uniform decay time constant of the gyroscope resonant structure, and f xω f yω These represent the forces per unit mass along the principal rigid axes, x and x. ω y ω These represent the vibration displacements along the principal rigid axis.

[0046] When voltages u1(t) and u2(t) are applied to the two pairs of driving electrodes respectively, the effective forces generated are f1 and f2, and the angles between f1 and f2 and the gyroscope driving direction (x-axis) are both π / 8, thus:

[0047]

[0048] When achieving orthogonal error suppression, f yω =0, that is, f1sin(π / 8+θ) ω )+f2sin(π / 8-θ ω ) = 0, that is:

[0049]

[0050] Therefore, refer to Figure 6 The orthogonal error suppression method in this embodiment specifically includes the following steps:

[0051] Step 1: When the gyroscope is in a stationary state, drive voltages u1(t) and u2(t) are applied to two adjacent drive electrodes in the gyroscope drive direction to make the gyroscope oscillate. Here, u1(t) and u2(t) are sinusoidal signals and are in phase and have the same frequency.

[0052] Step 2: Connect two adjacent detection electrodes in the gyroscope detection direction to two adjustable gain amplifier circuits, such that K1 / K2≡u1 / u2, where K1 and K2 are the amplification factors of the two amplifier circuits, and u1 and u2 are the amplitudes of the driving voltages u1(t) and u2(t), respectively; the angle between the driving electrode corresponding to u1 and the detection electrode corresponding to K1, and between the driving electrode corresponding to u2 and the detection electrode corresponding to K2, is 90° / N+α×360° / 2N, where α=0,1,…,2N-1.

[0053] Step 3: When the amplitudes of the driving voltages u1(t) and u2(t) change, the output signal after amplification and superposition by the detection electrodes will also change accordingly. Adjust the amplitudes of voltages u1(t) and u2(t) individually or selectively until the output signal e(t) after amplification and superposition by the two adjacent detection electrodes is 0. At this point, there is also... This achieves orthogonal error suppression.

[0054] In the specific implementation process, the amplitudes of the driving voltages u1(t) and u2(t) are adjusted separately or selectively as follows: First, u1(t) and u2(t) are set to a certain initial reference value and u1(t) = u2(t). At the same time, K1 and K2 are set to a certain initial reference value and K1 = K2. Then, the amplitude of u1(t) is gradually reduced, and K1 is also reduced at the same time. The change of the output signal e(t) after the detection electrode is amplified and superimposed is observed: If e(t) also decreases, u1(t) is reduced until e(t) = 0. Otherwise, u1(t) is adjusted back to the initial reference value, K1 is also adjusted back to the initial reference value, and the amplitude of u2(t) is gradually reduced, and K2 is reduced at the same time until e(t) = 0.

[0055] It is worth noting that after achieving orthogonal error suppression by adjusting the amplitudes of the driving voltages u1(t) and u2(t), if the gyroscope is used for rotation measurement, the ratio of the amplitudes of voltages u1(t) and u2(t) and the ratio of the amplification factors of the two amplifier circuits must remain unchanged. However, the magnitudes of the driving voltages u1(t) and u2(t) and the amplification factors of the two amplifier circuits can be adjusted according to actual needs. In addition, since the ring-shaped microelectromechanical gyroscope in this embodiment is an electromagnetic induction gyroscope, that is, driven by the Ampere force experienced by the current in the magnetic field, in step 1 above, AC currents i1(t) and i2(t) of the same frequency and phase can be applied to the two adjacent driving electrodes respectively, and in step 2, K1 / K2≡i1 / i2 can be kept, and in step 3, the amplitudes of currents i1(t) and i2(t) can be adjusted separately or by choice.

[0056] Even after achieving orthogonality error suppression, the gyroscope is still inevitably subject to frequency splitting between the first and second modes during actual measurement. In this embodiment, the resonant structure of the ring-shaped microelectromechanical gyroscope preferably uses fused silica material, and the resonant frequency increases with temperature above 50K. Therefore, in practical applications, if frequency splitting exists between the first and second modes, a voltage can be applied to the electrode corresponding to the lower-frequency mode. Under the Joule heating effect, the overall temperature of the gyroscope's resonant structure increases, and the frequencies of both the first and second modes also increase simultaneously. The overall temperature of the region corresponding to the low-frequency mode is higher than that of the region corresponding to the high-frequency mode, resulting in a greater frequency increase in the low-frequency mode than in the high-frequency mode. Therefore, controlling the magnitude of the voltage or current can reduce the frequency splitting between the two degenerate modes, achieving mode matching.

[0057] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for suppressing orthogonal errors in a ring-shaped microelectromechanical gyroscope, characterized in that, The ring-shaped microelectromechanical gyroscope has a pair of adjacent and independent driving electrodes in the gyroscope driving direction, and a pair of adjacent and independent detection electrodes in the gyroscope detection direction. The orthogonal error suppression method includes: In the gyroscope driving direction, driving voltages are applied to two adjacent driving electrodes to generate driving force, and the resultant force of the two driving forces is aligned with the direction of the gyroscope's principal stiffness axis. In the gyroscope detection direction, the electrical signals generated by two adjacent detection electrodes are amplified by two independent, adjustable-gain amplifier circuits and then superimposed. By adjusting the amplification factor of the two amplifier circuits, orthogonal error suppression is achieved, specifically: The ratio of the amplification factors of the two amplifier circuits is adjusted to be equal to the ratio of the amplitudes of the driving voltages applied to the two pairs of driving electrodes, thereby achieving quadrature error suppression.

2. The method for suppressing orthogonal errors in a ring-shaped microelectromechanical gyroscope according to claim 1, characterized in that, The driving voltage applied to the two pairs of adjacent driving electrodes is a sinusoidal signal and is in phase and frequency.

3. The method for suppressing orthogonal errors in a ring-shaped microelectromechanical gyroscope according to claim 2, characterized in that, Specifically, the direction of the resultant force of the two driving forces is aligned with the direction of the gyroscope's principal stiffness axis: The amplitude of the driving voltage applied to the two driving electrodes can be changed individually or by choosing one of them to change the magnitude and direction of the resultant force of the two driving forces, so that the direction of the resultant force of the two driving forces is consistent with the direction of the principal stiffness axis of the gyroscope.

4. The method for suppressing orthogonal errors in a ring-shaped microelectromechanical gyroscope according to claim 1, 2, or 3, characterized in that, The orthogonal error suppression method specifically includes the following steps: Step 1: Keep the top stationary; Step 2: Apply a driving voltage to two adjacent driving electrodes in the gyroscope driving direction. u 1( t )and u 2( t This causes the gyroscope to vibrate, among which... u 1( t )and u 2( t Same frequency and phase; Step 3: Connect two pairs of adjacent detection electrodes in the gyroscope detection direction to two adjustable gain amplifier circuits, and make... K 1 / K 2≡ u 1 / u 2, of which, K 1. K 2 represents the amplification factor of the two amplifier circuits, u 1. u 2 represents the driving voltage. u 1( t ), u 2( t The amplitude of ) Step 4, adjust individually or selectively. u 1( t )and u 2( t The amplitude of the signal is adjusted until the output signal after the amplification and superposition of the two adjacent detection electrodes is 0, thus achieving orthogonal error suppression.

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