KR100657424B1 - A method for measuring 1-axis angular velocity and 2-axes velocities with a vibrating micro gyroscope having one mass - Google Patents

Abstract

A method for measuring 1-axis angular velocity and 2-axis linear acceleration of a vibration-type micro gyroscope having singular mass is provided to automatically compensate clearance and damping coefficient by using the gyroscope. The internal motion path of a gyroscope is defined, and the path of a mass element is detected by using detection electrodes(35,36) of the gyroscope. It is determined whether the path of the mass element is identical with the defined internal motion path. Drive electrodes(33,34) are controlled to follow the defined path. Clearance, damping coefficient, angular velocity, and linear acceleration are automatically identified. The drive electrodes are additionally controlled on the basis of the above identified values, and signals of the angular velocity and linear acceleration are processed.

Description

A Method for Measuring 1-axis Angular Velocity and 2-axes Velocities with a Vibrating Micro Gyroscope having One Mass}

1 is a schematic diagram of a conventional micro accelerometer.

Figure 2 is a schematic diagram showing the structure of a conventional vibrating micro one-axis gyroscope equipped with one mass element.

3 is a block diagram illustrating a control method according to the present invention;

4 is a graph illustrating a path that a mass element of a gyroscope should follow.

5 is a schematic diagram of a circuit design of a motion following controller, automatic identification and signal processor according to the present invention;

6 is a graph showing a correction error of the manufacturing tolerance and the damping coefficient of the gyroscope structure according to the embodiment of the present invention.

Figure 7 is a graph comparing the input value and the output value of the angular velocity and linear acceleration according to the embodiment of the present invention.

** Description of the symbols for the main parts of the drawings **

11: mass element 12: support beam

13: detection electrode

21: mass element 22: drive beam

23, 24: drive electrode 25, 26: detection electrode

31: mass element 32: drive beam

33, 34: drive electrode 35, 36: detection electrode

371: internal motion generating unit

372: movement following control unit

373: Automatic East Government

374: feed forward control unit

375: signal processing unit

51, 52: output signal of the internal motion generating unit

53: output signal of the motion tracking controller

54: Parameter Adaptation Algorithm (PAA)

55: auto-correction output signal

56: low pass filter (LPF)

57: control gain

The present invention relates to a vibration type micro gyroscope and an accelerometer sensor, which are widely used for the automatic navigation of small vehicles and mobile vehicles, the stabilization device of a camera, the attitude control system, and the vibration of a high-rise building. The present invention relates to a method for simultaneously implementing a 1-axis gyroscope and a 2-axis accelerometer sensor that automatically corrects machining errors and damping coefficients inherent in a structure using an axis-gyroscopic structure.

Gyroscopes and accelerometers are sensors that measure the angular and linear accelerations used in inertial navigation and inertial guidance systems such as aircraft, ships, and automobiles. Gyroscopes have been used for a long time in missiles, ships, aircrafts, etc., but are now used for civil purposes such as the above-mentioned military purposes as well as automatic navigation of small aircraft and mobile vehicles as described above, and stabilization devices for cameras. This situation is expanding greatly. Gyroscopes by the purpose of the former (used for missiles, ships, aircraft, etc.) are produced through precise machining and assembly processes, which has the advantage of being able to measure precise and accurate angular velocity and linear acceleration. In addition, the manufacturing cost is high and it is inevitable to have an enlarged structure, which is not suitable for general industrial and household appliances. Therefore, to overcome this, Japan's Murata has developed a miniature gyroscope with a piezoelectric element attached to a triangular prism-shaped beam, which is used as a camera shake sensor for Sony and Matsushita video cameras. Tokin Corp. has developed a small gyroscope with an improved cylindrical beam beam to overcome the difficulties in fabricating a gyroscope with such piezoelectric elements. However, it is pointed out that such a small gyroscope is also made of small parts requiring precision machining, difficult to manufacture and expensive, and difficult to develop integrally as it is made of a large number of mechanical parts.

In modern times, due to the accumulation of micro machining technology, many mechanical products can be miniaturized. Micro gyroscopes manufactured by ultra precision machining technology are commercialized, and are disclosed in US Patent No. 5349855 developed by CSDL. A comb motor type gyroscope using a tuning fork mode is typically used. Vibration type micro gyroscopes have high sensitivity, low cost, and small size, and solve the disadvantages of conventional rotary or optical gyroscopes, which include one linear mass element, two linear mass elements, or one cylinder and The angular velocity can be measured by measuring the characteristic that the amount of displacement of the mass element in the direction perpendicular to the resonance in proportion to the rotational angular velocity in proportion to the rotational angular velocity while resonating the circular mass element using electromagnetic or electrostatic force. However, such a gyroscope also has to match the natural frequency in each direction in which vibration occurs, but it is very difficult to process within a predetermined machining error that satisfies this condition. There are many things that need to be improved, such as poor linearity. Therefore, there has been a continuing need for gyroscopes to obtain accurate measurements while having a smaller and simpler structure.

On the other hand, in order to measure the three-dimensional motion of the rigid body (rigid body) typically uses a six-freedom inertial sensor unit in which three gyroscopes and three accelerometers are arranged at right angles to each other. Since it is sufficient to assume a two-dimensional plane in the case of a moving path of a vehicle or a motion of a home robot, a three-degree of freedom in which one-axis gyroscope and two-axis accelerometer are disposed at right angles to each other to measure the two-dimensional movement. Use an inertial sensor unit.

1 illustrates a conventional micro uniaxial-accelerometer sensor. The mass element 11 is supported by the support beam 12, and the detection electrode 13 for detecting the displacement of the mass element 11 is formed in the shape of comb teeth. When an inertial force is applied, the mass element 11 moves in the Y-axis direction defined in FIG. 1, at which time, an opposing area formed between the electrodes of the mass element 11 is changed, thereby changing capacitance (C) between the electrodes. Done. Since the change in capacitance is proportional to the applied inertia force, the linear acceleration can be measured by measuring it.

2 illustrates a vibrating micro uniaxial-gyroscope sensor with a conventional single mass element 21. The mass element is supported by the drive beam 22 so that the mass element 21 can vibrate in the X-axis direction defined in FIG. The drive electrode 23 for vibrating the mass element 21 in the X-axis direction and the detection electrode 25 for detecting the vibration of the mass element 21 in the X-axis direction are formed in the shape of a comb. The detection electrode 26 for detecting the vibration of the mass element 21 in the axial direction is also formed in the shape of a comb teeth. When the rotational angular velocity is applied, the mass element 21 also vibrates in the Y-axis direction defined by FIG. 2 due to the Coriolis force. At this time, the opposing area formed between the electrodes of the mass element 21 is changed to change between the electrodes. The capacitance of will change. Since the change in capacitance is proportional to the applied rotational angular velocity, the angular velocity can be measured by measuring it.

However, such a conventional gyroscope is not only in the Coriolis force but also in the Y-axis direction defined by FIG. This causes vibration, which causes measurement error, measurement range reduction, sensitivity decrease, and scale factor instability. Conventionally, in order to compensate for such a cause, an initial manual correction or a closed loop controller for canceling vibration in the Y-axis direction is used. The X-axis, which is a prior art idea of a vibrating gyroscope having a single mass element defined in FIG. In the detection method in the Y-axis, the influence of the inertia force and the coupled damping coefficient of the XY axis cannot be eliminated.

On the other hand, if the inertial force, which is one of the causes of the conventional gyroscope measurement, can be measured, not only the accuracy of the gyroscope can be measured, but also the linear acceleration of two axes can be measured. Since a single axis gyroscope and a two axis accelerometer sensor can be implemented, a three degree of freedom inertial sensor unit in which a conventional single axis gyroscope and a two axis accelerometer are disposed at right angles to each other can be implemented as a single structure.

Accordingly, the present invention has been made to solve the problems of the prior art as described above, an object of the present invention is to provide a single axis angular velocity and two axis linear acceleration measurement method of a single mass element-based vibration type gyroscope. More specifically, by using a conventional micro gyroscope structure having a single mass element, it is possible to measure not only the angular velocity but also linear acceleration, so that the uniaxial-angular accelerometer and the biaxial linear accelerometer can be simultaneously implemented on a single structure. The purpose is to provide a way to.

In order to achieve the above object, the single-axis angular velocity and bi-axial linear acceleration measuring method of a single mass element-based vibratory gyroscope of the present invention includes: a) defining a path of an internal motion of a gyroscope; b) detecting the path of the mass element through the gyroscope's detection electrode; c) determining whether the path of the mass element detected in step b) coincides with the path of internal motion defined in step a); d) controlling the drive electrode such that the mass element follows the path defined in step a); e) automatically identifying manufacturing tolerances, damping coefficients, angular velocities and linear accelerations on the structure characteristics; f) further controlling the drive electrode using the identification value obtained in step e); g) processing the angular velocity and linear acceleration signals obtained in step e); Characterized in that consists of.

Hereinafter, a method for measuring uniaxial angular velocity and biaxial linear acceleration of a single mass element based vibration type gyroscope according to the present invention having the configuration as described above will be described in detail with reference to the accompanying drawings.

2 illustrates a vibrating micro uniaxial-gyroscope sensor with a conventional single mass element 21. When x and y are displacements of the mass elements in the X and Y axes shown in Fig. 2, the equation of motion of the mass elements is expressed by the following equation in consideration of the influence of manufacturing tolerance, damping coefficient and inertia force.

는 각각 X축과 Y축의 고유진동수이며,

는 감쇠계수이고,

는 X-Y축의 커플드(coupled)된 진동수 및 감쇠계수이며,

는 인가된 각속도이고,

는 관성 가속도, 그리고

는 각 축의 제어입력이다.here

Are the natural frequencies of the X and Y axes, respectively.

Is the damping coefficient,

Is the coupled frequency and damping coefficient of the XY axis,

Is the applied angular velocity,

Is the inertia acceleration, and

Is the control input of each axis.

 The natural frequencies of the X and Y axes may differ from the values designed due to the influence of manufacturing tolerances. The coupled frequency and damping coefficients of the X-Y axes are values that should be corrected as errors due to manufacturing tolerances. It is the purpose of the gyroscope to measure the applied angular velocity, and the purpose of the accelerometer sensor to measure the applied inertial acceleration. According to the present invention, it is possible to identify not only the applied angular velocity and inertial acceleration but also the error of natural frequency and the coupled frequency and damping coefficient according to manufacturing tolerances.

Figure 3 shows a schematic configuration of a control method for a micro gyroscope structure according to the present invention. The internal motion generating part 371 of FIG. 3 is a part defining internal motion so that the structure satisfies a persistent excitation condition, that is, generates a path to be followed by the mass element 31 of the gyroscope. . In Fig. 4, the path to be followed by the mass element of the gyroscope is illustrated as a waveform of a sine wave / cosine wave. At this time, it is important that the waveform frequencies on the X-axis and the Y-axis shown in FIG. 3 are different from each other. This is a clear difference from the fact that the sensitivity of the conventional gyroscope technology to match the resonance frequency of the X-axis and the Y-axis to improve the sensitivity.

The motion following controller 372 of FIG. 3 controls the voltages of the two driving electrodes 33 and 34 of the vibratory gyroscope so that the mass element follows a predefined path. 5 shows an embodiment of the motion following controller. The X-axis and Y-axis waveforms 51 and 52 of FIG. 5 are signals of the internal motion generating unit 371 of FIG. 3, and the mass elements (detected by the two detection electrodes 35 and 36 of FIG. Compared to the paths 511 and 521 of FIG. 31, the feedback control is performed, but the motion tracking controller 372 advantageously has a quick response characteristic according to the input signal, so that the proportional derivative can satisfy such conditions. Control 57 is performed.

The automatic identification part 373 of FIG. 3 automatically identifies manufacturing tolerances, damping coefficients, angular velocity and linear acceleration inherent in the structure of the gyroscope. 5 illustrates an embodiment of automatic coordination. The internal motion generator signals 51 and 52 and the motion follower control signal 53 of FIG. 5 are MUXed so that the angular velocity applied through the parameter adaptation algorithm (PAA) 54 and the natural frequency according to the manufacturing tolerance. The error and coupled frequency and damping coefficients and the applied inertia acceleration are identified. The parameter adaptation algorithm 54 is calculated by the following equation.

는 각각 고유진동수의 오류, 감쇠계수, 인가된 각속도, 인가된 관성가속도의 동정값이다. 또

는 운동추종제어부 신호이며,

은 내부운동발생부 신호이고,

는 검출한 질량소자의 경로이며,

는 각각 비례상수이다.here

Are the identification values of the natural frequency error, the damping coefficient, the applied angular velocity, and the applied inertia acceleration. In addition

Is the signal of the motion follower control unit,

Is the internal motion generator signal,

Is the path of the detected mass element,

Are respectively proportional constants.

As shown in the embodiment of FIG. 5, the feedforward control unit 374 of FIG. 3 mutes the identification value 55 and the internal motion generation unit signals 51 and 52 obtained from the automatic correction unit 373 to drive the gyroscope. The voltage of the electrodes 33 and 34 is further controlled.

The signal processor 375 of FIG. 3 processes the linear acceleration and angular velocity signals obtained by the auto-tuning part 373 through the low frequency filter 56 in consideration of the bandwidth, and processes them into detection signals of the required type such as angular velocity and linear acceleration. do.

6 is a graph showing a manufacturing tolerance of the gyroscope structure and attenuation coefficient correction error according to the above-described embodiment of the present invention, and the graph of FIG. 7 is a single mass device-based gyro according to the present invention described above. This graph illustrates the angular velocity and linear acceleration measured by the scope and accelerometer. As shown, as a result of controlling the conventional vibrating micro gyroscope in the manner described above, it can be seen that the effect of manufacturing error is eliminated and the angular velocity of one axis and the linear acceleration of two axes can be measured simultaneously as desired. .

The present invention is not limited to the above-described embodiments, and the scope of application is not limited to those of ordinary skill in the art to which the present invention pertains without departing from the gist of the present invention as claimed in the claims. Of course, various modifications are possible.

As described above, according to the present invention, by using the conventional vibration-type micro gyroscope structure equipped with a single mass element as it is, as well as automatically correct the manufacturing error (processing error, damping coefficient, etc.) inherent in the structure, 1 By simultaneously measuring the axial angular velocity and the two-axis linear acceleration, the three degree of freedom inertial sensor unit can be realized as a single structure. In addition, as described above, by using the existing vibration type micro gyroscope as it is, the control method can be measured at the same time by simultaneously measuring the axial angular velocity and the 2-axis linear acceleration. The effect is that it can show savings and excellent compatibility.

Claims (4)

a) defining a path of internal movement of the gyroscope; b) detecting the path of the mass element through the gyroscope's detection electrode; c) determining whether the path of the mass element detected in step b) coincides with the path of internal motion defined in step a); d) controlling the drive electrode such that the mass element follows the path defined in step a); e) automatically identifying manufacturing tolerances, damping coefficients, angular velocities and linear accelerations on the structure characteristics; f) further controlling the drive electrode using the identification value obtained in step e); g) processing the angular velocity and linear acceleration signals obtained in step e); Single axis angular velocity and two axis linear acceleration measurement method of a single mass element based vibration type gyroscope, characterized in that consisting of. According to claim 1, wherein the definition of the internal motion of the gyroscope in step a), 1 axis angular velocity and 2 axis of single mass device-based vibratory gyroscope characterized by defining the gyroscope's internal motion by recognizing the gyroscope structure as a device that generates internal motion that satisfies a persistent excitation condition Linear acceleration measurement method. The gyroscope of claim 2, wherein the gyroscope in step a) is defined as 1-axis angular velocity and 2-axis linear acceleration measurement method of a single mass element-based vibration type gyroscope characterized in that the waveform frequency to the X axis and Y axis in the plane is defined as different. The vibration control gyroscope according to claim 2, wherein the following equation is used as an operation for automatically identifying manufacturing tolerances, damping coefficients, and angular velocity and linear acceleration inherent in the structure of the vibratory gyroscope. 1-axis angular velocity and 2-axis linear acceleration measurement method.

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