KR102452565B1 - Design method of multi-axis MEMS gyro sensor with low cross-axis sensitivity - Google Patents

Abstract

The proposed technology relates to a design method for a multi-axis MEMS gyro sensor having low rudder sensitivity, and more particularly, to a design method for reducing cross-axis sensitivity of a multi-axis MEMS gyro sensor having a single structure.

Description

Design method of multi-axis MEMS gyro sensor with low cross-axis sensitivity

The proposed technology relates to a design method for a multi-axis MEMS gyro sensor having low rudder-axis sensitivity, and more particularly, to a design method for reducing cross-axis sensitivity of a multi-axis MEMS gyro sensor having a single structure.

In general, a micro electro mechanical system (MEMS) is a technology for implementing mechanical and electrical components using a semiconductor process, and a representative example of a device using the MEMS technology is a MEMS gyroscope that measures angular velocity.

The gyroscope measures the angular velocity by sensing a Coriolis force generated when a rotational angular velocity is applied to an object moving at a predetermined velocity. At this time, the Coriolis force is proportional to the cross product of the movement speed and the rotational angular velocity due to an external force.

In addition, in order to sense the generated Coriolis force, the gyroscope has a mass that vibrates therein. Typically, the direction in which the mass in the gyroscope is driven is referred to as the direction in which the rotational angular velocity is input to the gyroscope is referred to as the input direction, and the direction in which the Coriolis force generated in the mass is sensed is referred to as the sensing direction. The excitation direction, the input direction, and the sensing direction are set to be orthogonal to each other in space.

In general, in a gyroscope using the MEMS technology, two directions (horizontal direction or x-y direction) that are parallel and orthogonal to the plane formed by the bottom wafer substrate and one direction perpendicular to the plate surface of the substrate (referred to as vertical or z direction) Set the coordinate axes in three directions.

Accordingly, the gyroscope is divided into an x-axis (or y-axis) gyroscope and a z-axis gyroscope. The x-axis gyroscope is a gyroscope whose input direction is the horizontal direction, and the y-axis gyroscope detects displacement on a plane based on an axis in the vertical direction to the x-axis gyroscope, but in principle, it is substantially the same as the x-axis gyroscope. do.

In order to measure the angular velocity applied in the horizontal direction using the x-axis gyroscope, either the excitation direction or the sensing direction should be set to the vertical direction.

Meanwhile, in a multi-axis MEMS gyroscope having a single structure, cross-axis sensitivity (CAS) is one of the important issues.

The cross-axis sensitivity is caused by a problem of assembly and test setting errors, and a method for reducing the cross-axis sensitivity to a minimum is required.

Korean Patent Registration No. 10-1984078

The present invention was invented to solve the above problems, and an object of the present invention is to provide a design method capable of reducing the cross-axis sensitivity of a multi-axis MEMS gyro sensor having a single structure.

In the design method of the multi-axis MEMS gyro sensor having low rudder sensitivity of the present invention for achieving the above object,

)과 Y축으로 이동하는 구동 질량부의 구동 변위 진폭(

)이 서로 다르고, The driving displacement amplitude of the driving mass moving along the X axis (

) and the driving displacement amplitude of the driving mass moving along the Y axis (

) are different,

) 와 Y축을 중심으로 비틀림 거동하는 감지 주파수와의 차이(

)가 서로 다른 경우, The difference (

) and the difference between the detection frequency of torsional behavior around the Y-axis (

) are different,

,

,

,

,

: 구동 변위 진폭 비율,

: 감지 주파수 차이 비율)(here,

: drive displacement amplitude ratio,

: detection frequency difference ratio)

It is characterized in that it satisfies the formula.

The coupling portion has a Z-shaped shape with a central portion separated and spaced apart and includes a spring beam connecting two driving masses forming a gap.

The driving mass is

a first driving mass part and a third driving mass part disposed to face each other, positioned along the X-axis, and moving along the Y-axis;

It is disposed to face each other, is positioned along the Y-axis, and characterized in that it includes a second driving mass part and a fourth driving mass part moving along the X-axis.

According to the present invention, it is possible to reduce the cross-axis sensitivity of the multi-axis MEMS gyroscope having a single structure.

1 is a conceptual diagram of a single structure MEMS gyro sensor according to the present invention.
2 is a conceptual diagram of a MEMS gyro sensor having a single structure when driving displacement amplitudes are not the same according to the present invention.
3 is a conceptual diagram of a frequency arrangement of 2;
4 is an initial design resonant frequency of FIG. 2;
5 is a cross-axis sensitivity result table of FIG.
6 is a resonant frequency to which the design method of the present invention is applied in FIG.
7 is a cross-axis sensitivity result table of FIG.
8 is a conceptual view of a change in the position of the coupling part spring in FIG. 2 .
9 is a graph of cross-axis sensitivity according to a change in position of FIG. 8;
10 is a conceptual diagram of a MEMS gyro sensor having a single structure when the driving displacement amplitude is the same according to the present invention.
11 is a conceptual diagram of the frequency arrangement of FIG. 10;
Figure 12 (a) is a conceptual view of the coupling part applied to Figure 2, Figure 12 (b) is a conceptual view of the coupling part applied to Figure 10.
13 is a symbol table used in the formula of the present invention.

The features and effects of the present invention described above will become more apparent through the following detailed description in relation to the accompanying drawings, and accordingly, those of ordinary skill in the art to which the present invention pertains can easily implement the technical idea of the present invention. will be able Since the present invention can have various changes and can have various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention. The terms used in the present application are only for describing specific embodiments, and are not intended to limit the present invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The present invention relates to a design method of a multi-axis MEMS gyro sensor having low rudder sensitivity, and more particularly, to a design method for reducing cross-axis sensitivity of a multi-axis MEMS gyro sensor having a single structure.

The low sensitivity of the rudder axis means that the sensitivity to the other axis orthogonal to the input axis to be detected is low. In terms of selectivity of the sensor, the lower the rudder sensitivity, the more advantageous.

The reference value may be determined according to various needs, and may be, for example, an average value of sensitivities measured by a plurality of specific sensors.

1 is a conceptual diagram of a MEMS gyro sensor having a single structure according to the present invention.

The gyro sensor of the present invention shown in FIG. 1 is positioned between a plurality of driving masses moving about one of three axes perpendicular to each other, and the plurality of driving masses spaced apart from each other by a predetermined distance. and a coupling part selectively connecting the plurality of driving mass parts.

The plurality of driving masses are all displaced by an inertial force or a Coriolis force, and are positioned on a plane composed of the X-axis and the Y-axis in a stationary state.

The driving mass portion is symmetrical to each other, positioned along the X axis, and has a first and a third driving mass portion moving along the X axis, and a second driving mass portion symmetrical to each other, positioned along the Y axis, and moving along the Y axis. It is configured to include a second driving mass part and a fourth driving mass part.

In addition, it is preferable that the Z-axis and the central portion are positioned at the intersection of the X-axis and the Y-axis.

Preferably, the plurality of driving masses are connected to the central part, and the central part is positioned on the same plane as the plurality of driving masses when the plurality of driving masses are in a stationary state.

At this time, the first to fourth driving mass parts are connected to the central part by a connecting means made of a flexible material in a form surrounding the central part so that a plurality of driving mass parts can move within a predetermined range. desirable.

The plurality of driving masses may move about at least one of an X-axis, a Y-axis, and a Z-axis in three directions that are all perpendicular to each other.

In the present invention, the method for reducing the cross-axis sensitivity of the gyro sensor will be described for two cases, respectively.

FIG. 2 shows a conceptual diagram of a MEMS gyro sensor having a single structure when the driving displacement amplitudes are not the same according to the present invention, and FIG. 3 shows a conceptual diagram of the frequency arrangement of 2 .

In FIG. 2, as shown in FIG. 12(a), the coupling part has a Z-shaped shape in which a central part is separated and spaced apart, and a spring beam connected from each of the two driving masses forming the gap; and a groove formed in each of the two driving masses in a direction perpendicular to the gap, and a spring structure connecting the spring beam.

)과 Y축으로 이동하는 구동 질량부의 구동 변위 진폭(

)이 서로 다르고, 수평 방향의 구동 주파수와 X축을 중심으로 비틀림 거동하는 감지 주파수와의 차이(

)와 Y축을 중심으로 비틀림 거동하는 감지 주파수와의 차이(

)가 서로 다른 경우, 교차축감도(Cross Axis Sensitivity)를 최소화하기 위해서는 하기 수학식 1을 만족시켜야 한다.In the gyro sensor configured as described above, the driving displacement amplitude (

) and the driving displacement amplitude of the driving mass moving along the Y axis (

) are different, and the difference between the driving frequency in the horizontal direction and the detection frequency that is torsional about the X-axis (

) and the difference (

) are different from each other, Equation 1 below must be satisfied in order to minimize Cross Axis Sensitivity.

은 구동 변위 진폭 비율,

은 감지 주파수 차이 비율을 의미한다.In Equation 1 above

is the drive displacement amplitude ratio,

is the detection frequency difference ratio.

)는 Y축에서 높은 교차축감도(

)를 유발하며, 낮은 Y축 주 감도(

)는 X축에서 낮은 교차축감도(

)를 유발한다.Cross-axis sensitivity is directly dependent on the principal sensitivity of the orthogonal axis, with high X-axis principal sensitivity (

) is the high cross-axis sensitivity (

), and low y-axis main sensitivity (

) is the low cross-axis sensitivity (

) causes

Therefore, to reduce the cross-axis sensitivity, the main sensitivity should be normalized first.

The sensing frequency and the driving displacement method are designed according to the following equations (1, 2).

(X-Axis Sensitivity)Formula (1)

(X-Axis Sensitivity)

(Y-Axis Sensitivity)Equation (2)

(Y-Axis Sensitivity)

In order to normalize the main sensitivity, the ratio of the driving displacement amplitudes of the X-axis and the Y-axis should be close to 1, and the ratio of the detection frequency difference between the X-axis and the Y-axis should also be close to 1.

)과 Y축으로 이동하는 구동 질량부의 구동 변위 진폭(

)의 비인

와, 수평 방향의 구동 주파수와 X축을 중심으로 비틀림 거동하는 감지 주파수와의 차이(

)와 Y축을 중심으로 비틀림 거동하는 감지 주파수와의 차이(

)의 비인

는 상기 [수학식 1]인

를 만족해야 한다.Therefore, for low cross-axis sensitivity, the driving displacement amplitude (

) and the driving displacement amplitude of the driving mass moving along the Y axis (

) of

and the difference between the driving frequency in the horizontal direction and the detection frequency that is torsional about the X-axis (

) and the difference (

) of

is [Equation 1]

must be satisfied

와

를 만족하게 되어 상기 교차축감도가 최소화된다.When the above [Equation 1] is satisfied,

Wow

, so that the cross-axis sensitivity is minimized.

The above equation is verified through cross-axis sensitivity analysis with respect to the change in the position of the spring beam.

4 shows the initial design resonance frequency of FIG. 2 , and FIG. 5 shows the cross-axis sensitivity result table of FIG. 4 .

4 to 5 , the cross-axis sensitivity is calculated to be 0.301%, which is a relatively high value.

6 shows the resonance frequency to which the design method of the present invention is applied in FIG. 2 , and FIG. 7 shows the cross-axis sensitivity result table of FIG. 6 .

As shown in FIGS. 6 to 7 , the cross-axis sensitivity is calculated as a relatively low value of 0.045%, and it can be seen that the cross-axis sensitivity is reduced by 85.1% compared to FIG. 5 .

8 is a conceptual diagram of a change in the position of the spring beam in FIG. 2 , and FIG. 9 shows a graph of cross-axis sensitivity according to the change in position of FIG. 8 .

In order to verify [Equation 1], cross-axis sensitivity analysis was performed by placing the spring beam at three different points.

을 만족할 때 교차축감도가 최소임을 확인할 수 있다.As shown in Figure 9,

When , it can be confirmed that the cross-axis sensitivity is minimal.

In addition, when the spring beam is disposed in the center as shown in FIG. 8(b), the cross-axis sensitivity is lower than when the spring beam is disposed inside as shown in FIG. 8(a) and outside as shown in FIG. 8(c). that can be checked

10 is a conceptual diagram of a MEMS gyro sensor having a single structure when the driving displacement amplitude is the same according to the present invention, and FIG. 11 is a conceptual diagram of the frequency arrangement of FIG. 10 .

In Fig. 10, the coupling portion has a simple folded shape, as shown in Fig. 12(b), a spring beam connecting the two driving masses forming the gap, and perpendicular to the gap. and a groove formed in each of the two driving masses in the direction, and a spring structure connecting the spring beam.

)과 Y축으로 이동하는 구동 질량부의 구동 변위 진폭(

)이 서로 동일하고, 수평 방향의 구동 주파수와 X축을 중심으로 비틀림 거동하는 감지 주파수와의 차이(

) 와 Y축을 중심으로 비틀림 거동하는 감지 주파수와의 차이(

)가 서로 동일한 경우, 교차축감도(Cross Axis Sensitivity)를 최소화하기 위해서는 하기 수학식 2를 만족시켜야 한다.In the gyro sensor configured as described above, the driving displacement amplitude (

) and the driving displacement amplitude of the driving mass moving along the Y axis (

) is equal to each other, and the difference between the driving frequency in the horizontal direction and the detection frequency for torsional behavior around the X axis

) and the difference between the detection frequency of torsional behavior around the Y-axis (

) are equal to each other, in order to minimize Cross Axis Sensitivity, Equation 2 below must be satisfied.

은 구동 변위 진폭 비율,

은 감지 주파수 차이 비율을 의미한다.In Equation 2 above

is the drive displacement amplitude ratio,

is the detection frequency difference ratio.

First, in order to obtain the same frequency difference as the driving frequency, the sensing frequency as shown in FIG. 11 should be arranged.

을 만족할 때, 상기 구동 질량부 중 X축으로 이동하는 구동 질량부의 구동 변위 진폭(

)과 Y축으로 이동하는 구동 질량부의 구동 변위 진폭(

)이 서로 동일해진다.drive displacement amplitude ratio

When , the driving displacement amplitude (

) and the driving displacement amplitude of the driving mass moving along the Y axis (

) are equal to each other.

을 만족할 때, 수평 방향의 구동 주파수와 X축을 중심으로 비틀림 거동하는 감지 주파수와의 차이(

)와 Y축을 중심으로 비틀림 거동하는 감지 주파수와의 차이(

)가 서로 동일해 진다.In addition, the detection frequency difference ratio

When , the difference between the driving frequency in the horizontal direction and the detection frequency

) and the difference (

) are equal to each other.

을 만족해야 한다.Therefore, for low cross-axis sensitivity

should be satisfied with

와

를 만족하게 되어 상기 교차축감도가 최소화된다.If the above [Equation 2] is satisfied,

Wow

, so that the cross-axis sensitivity is minimized.

The detailed steps of the above-described 'design method of a multi-axis MEMS gyro sensor with low rudder sensitivity' may be performed in the form of a computer program executed by a computer. Specifically, the simulation of the sensor design method may be implemented in the form of a computer program (script) executed in COMSOL.

As a result, the sensor design method may be provided in the form of a computer program, the method and detailed steps may be performed by a processor, and may be stored in various recordable storage media.

Although the detailed description of the present invention described above has been described with reference to preferred embodiments of the present invention, those skilled in the art or those having ordinary knowledge in the technical field will be described later in the claims of the present invention And it will be understood that various modifications and variations of the present invention can be made without departing from the technical scope.

2: first drive mass part
4: second drive mass part
6: Third drive mass part
8: fourth driving mass part
10: central part
12: coupling part
14: Z-shaped spring beam
16: spring beam of simple folded shape

Claims (6)

a plurality of driving masses moving about one of three axes perpendicular to each other; and
In a design method for minimizing cross-axis sensitivity of a gyro sensor, comprising: a coupling part positioned between the plurality of driving mass parts spaced apart from each other by a predetermined distance and selectively connecting the plurality of driving mass parts;
The driving displacement amplitude (

) and the driving displacement amplitude of the driving mass moving along the Y axis (

) are different,
The difference (

) and the difference between the detection frequency of torsional behavior around the Y-axis (

) are different,

,

,

(here,

: drive displacement amplitude ratio,

: detection frequency difference ratio)
satisfying the formula
A method of designing a multi-axis MEMS gyro sensor with low rudder sensitivity, characterized in that According to claim 1,
The coupling part has a Z-shaped shape with a central part separated and spaced apart, and includes a spring beam connecting the two driving masses forming the gap. Design of a multi-axis MEMS gyro sensor with low rudder sensitivity Way. According to claim 1,
The driving mass part,
a first and a third driving mass symmetrical to each other, positioned along the X-axis, and moving along the X-axis;
symmetrical to each other, positioned along the Y axis, and comprising a second driving mass and a fourth driving mass moving along the Y axis.
A method of designing a multi-axis MEMS gyro sensor with low rudder sensitivity, characterized in that a plurality of driving masses moving about one of three axes perpendicular to each other; and
In a design method for minimizing the cross-axis sensitivity of a gyro sensor comprising a; a coupling part located between the plurality of driving mass parts spaced apart from each other by a predetermined distance and selectively connecting the plurality of driving mass parts with each other.
The driving displacement amplitude (

) and the driving displacement amplitude of the driving mass moving along the Y-axis (

) are equal to each other,
The difference (

) and the difference (

) are equal to each other,

(here,

: drive displacement amplitude ratio,

: detection frequency difference ratio)
satisfying the above formula
A method of designing a multi-axis MEMS gyro sensor with low rudder sensitivity, characterized in that 5. The method of claim 4,
wherein the coupling portion has a simple folded shape and includes a spring beam connecting the two drive masses forming the gap. 5. The method of claim 4,
The driving mass part,
a first and a third driving mass symmetrical to each other, positioned along the X-axis, and moving along the X-axis;
symmetrical to each other, positioned along the Y axis, and comprising a second driving mass and a fourth driving mass moving along the Y axis.
A method of designing a multi-axis MEMS gyro sensor with low rudder sensitivity, characterized in that

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