JP2014139561A - Angular velocity sensor calibration device and calibration method for the same - Google Patents

Abstract

To eliminate the output variation of an angular velocity sensor, the output of the angular velocity sensor can be calibrated very easily without using a rotating turntable.
An angle setting rotation drive device 3 rotates an inspection table 1 on which an angular velocity sensor 2 is mounted by a predetermined angle. The output integrating unit 5 outputs a first integrated value of the values output from the angular velocity sensor 2 during the rotational movement by the angle setting rotation driving device 3. The sensitivity correction unit 7 compares the first integrated value by the output integration unit 5 with the reference value stored in the reference value storage unit 6 and corrects the sensitivity of the angular velocity sensor 2 based on the comparison result. The angular velocity correction unit 8 corrects the angular velocity output based on the sensitivity corrected by the sensitivity correction unit 7 and outputs the corrected angular velocity. The offset measuring unit 4 measures the offset of the angular velocity sensor 2.
[Selection] Figure 3

Description

  The present invention relates to an angular velocity sensor calibration apparatus and a calibration method thereof, and more particularly, without using a turntable that rotates an angular velocity sensor before shipment at an accurate angular velocity in order to eliminate output variation of the angular velocity sensor. The present invention relates to an angular velocity sensor calibration apparatus and a calibration method thereof that can easily calibrate (sensitivity correction) the output of an angular velocity sensor.

  Conventionally, in the automobile industry, the machine industry, and the like, there is an increasing demand for sensors that can accurately detect the acceleration and angular velocity of a moving object. In general, acceleration in an arbitrary direction and an angular velocity in an arbitrary rotation direction act on an object that freely moves in a three-dimensional space. Therefore, in order to accurately grasp the movement of the object, it is necessary to independently detect the acceleration in each coordinate axis direction and the angular velocity around each coordinate axis in the XYZ three-dimensional coordinate system.

FIG. 1 is a perspective view for explaining the basic principle of a conventional one-dimensional angular velocity sensor using Coriolis force, and is a diagram for explaining the principle of angular velocity detection by a uniaxial angular velocity sensor described in Patent Document 1. It is.
In an XYZ three-dimensional coordinate system in which X, Y, and Z axes are defined with respect to a prismatic vibrator 10, when the vibrator 10 is rotating at an angular velocity ω with the Z axis as a rotation axis, the vibrator 10 Is given a vibration U that reciprocates in the X-axis direction, a Coriolis force F is generated in the Y-axis direction. That is, if the vibrator 10 is rotated about the Z axis while the vibrator 10 is vibrated along the X axis, a Coriolis force F is generated in the Y axis direction. This phenomenon is a mechanical phenomenon that has long been known as a Foucault pendulum, and the generated Coriolis force F is expressed by F = 2 m · v · ω. Here, m represents the mass of the vibrator 10, v represents the instantaneous speed of vibration of the vibrator 10, and ω represents the instantaneous angular speed of the vibrator 10.

  This uniaxial angular velocity sensor detects the angular velocity ω by utilizing the phenomenon described above. That is, the first piezoelectric element 11 is attached to the first surface of the prismatic vibrator 10, and the second piezoelectric element 12 is attached to the second surface orthogonal to the first surface. As the piezoelectric elements 11 and 12, plate-shaped elements made of piezoelectric ceramic are used. The piezoelectric element 11 is used to apply the vibration U to the vibrator 10, and the piezoelectric element 12 is used to detect the generated Coriolis force F. That is, when an AC voltage is applied to the piezoelectric element 11, the piezoelectric element 11 repeats expansion and contraction and vibrates in the X-axis direction. This vibration U is transmitted to the vibrator 10, and the vibrator 10 vibrates in the X-axis direction. As described above, when the vibrator 10 itself rotates at the angular velocity ω with the Z axis as the central axis in a state where the vibration U is applied to the vibrator 10, the Coriolis force F is generated in the Y axis direction due to the phenomenon described above. Since this Coriolis force F acts in the thickness direction of the piezoelectric element 12, a voltage V proportional to the Coriolis force F is generated on both surfaces of the piezoelectric element 12. Therefore, by measuring this voltage V, the angular velocity ω can be detected.

  This type of angular velocity sensor is rotated while being maintained at a specific temperature before shipment, and its signal characteristics are inspected by an angular velocity inspection device. For example, the one described in Patent Document 2 relates to an angular velocity sensor inspection table device, and the signal of the angular velocity sensor may fluctuate depending on the ambient temperature. Since it is necessary to inspect the temperature characteristics of all products, conventionally, when inspecting the temperature characteristics of angular velocity sensors, a rotating plate is installed in the thermostatic chamber, and the angular velocity sensor is mounted on the rotating plate. While maintaining the temperature at a specific temperature, the angular velocity sensor is rotated to inspect the signal characteristics.

In other words, an angular velocity sensor is mounted on a turntable that rotates at an accurate angular velocity, and the output from the angular velocity sensor is measured and calibrated by rotating the turntable at a constant angular velocity.
However, in this conventional inspection apparatus, since it takes time to obtain a stable constant angular velocity, in order to realize the inspection cycle time (for example, 5 to 15 seconds per one) of the angular velocity sensor, a test substrate is used. It was necessary to set a large number of angular velocity sensors in advance and inspect them at the same time. As a result, there is a problem that the design and production of the test board is very expensive, and the contact performance with the angular velocity sensor in a huge number of sockets must always be maintained and managed optimally. In addition, the entire inspection apparatus is increased in size, and there is a problem that it takes time to take in and out the test substrate to and from the thermostat.

  Regarding the signal processing of the angular velocity sensor, for example, in Patent Document 3, an error in the angular velocity signal output by the gyro sensor (an angular velocity error caused by a sensor mounting pitch angle, a vehicle pitch angle, a sensor sensitivity error, etc.) is corrected. An angular velocity correcting device and a correcting method thereof are disclosed.

JP 2007-309946 A JP 2011-257203 A JP 2009-139227 A

  By the way, the angular velocity sensor usually has output variations caused by manufacturing variations, and therefore the angular velocity sensor is calibrated before shipment. For example, consider a scene in which the angular velocity sensor is rotated at a speed of N ° per second. Assuming that the ideal output of the angular velocity sensor when the angular velocity sensor is rotated at a speed of N ° per second is α, there is a manufacturing variation in the angular velocity sensor. For example, a certain angular velocity sensor outputs 1.2α.

  In order to eliminate such an output variation of the angular velocity sensor, the angular velocity sensor before shipment is calibrated. Specifically, for an angular velocity sensor that produces an output of 0.8α, the output is calibrated (sensitivity correction) 5/4 times, and for an angular velocity sensor that produces an output of 1.2α, the output is 4 The calibration (sensitivity correction) is performed to make it / 5 times. Such calibration is extremely time consuming.

In addition, it is extremely difficult to prepare a turntable that rotates at an accurate angular velocity, and a period until the angular velocity of the turntable becomes constant is wasted. In other words, the conventional device has a problem that the signal output by the angular velocity sensor during the transition period of the set angular velocity is discarded.
The present invention has been made in view of such problems, and an object of the present invention is to use a turntable that rotates an angular velocity sensor before shipment at an accurate angular velocity in order to eliminate output variation of the angular velocity sensor. It is another object of the present invention to provide an angular velocity sensor calibration apparatus and a calibration method thereof that can calibrate (sensitivity correction) the output of the angular velocity sensor very easily.

  The present invention has been made to achieve such an object. The invention according to claim 1 is directed to an inspection table on which an angular velocity sensor is mounted, and a drive device that rotates the inspection table by a predetermined angle. An integration unit that outputs a first integrated value of a value output from the angular velocity sensor during the rotational motion, and the first integrated value and a reference value stored in a storage unit are compared, and the comparison An angular velocity sensor calibration apparatus comprising: a sensitivity correction unit that performs sensitivity correction of the angular velocity sensor based on a result.

  According to a second aspect of the present invention, in the first aspect of the present invention, the drive device rotates the inspection table by a first angle in a predetermined direction, and in a direction opposite to the predetermined direction. The accumulator is rotated by a second angle, and the accumulator is configured to output a second accumulated value of a value output from the angular velocity sensor while the examination table is rotated by the first angle, and the examination table is the second A value based on the difference between the value output from the angular velocity sensor and the third integrated value during the rotation of the angle is output as the first integrated value.

According to a third aspect of the present invention, in the second aspect of the present invention, the time for rotating the inspection table by the first angle and the time for rotating the inspection table by the second angle are substantially the same. equal.
In the invention according to claim 4, in the invention according to claim 2 or 3, the reference value is a value corresponding to a difference between the first angle and the second angle.

The invention described in claim 5 is the invention described in claim 1, further comprising an offset measuring unit for measuring an offset of the angular velocity sensor.
The invention according to claim 6 is the invention according to claim 1 or 5, wherein the reference value is a value corresponding to the predetermined angle.
According to a seventh aspect of the invention, in the invention of the sixth aspect, the inspection table is fold-rotated and driven.

  The invention according to claim 8 is output from the angular velocity sensor between the mounting step of mounting the angular velocity sensor on the inspection table, the rotation step of rotating the inspection table by a predetermined angle, and the rotational motion. An angular velocity having an output step of outputting a first integrated value of the value to be compared, and a correction step of comparing the first integrated value with a reference value and correcting the sensitivity of the angular velocity sensor based on the comparison result This is a sensor calibration method.

  The invention according to claim 9 is the invention according to claim 8, wherein the rotating step rotates the inspection table in a predetermined direction by a first angle and in a direction opposite to the predetermined direction. A step of rotating by a second angle, and the output step includes a second integrated value of a value output from the angular velocity sensor while the inspection table rotates by the first angle, and the inspection table A step of outputting, as the first integrated value, a value based on a difference between a value output from the angular velocity sensor and a third integrated value while rotating by the second angle;

The invention according to claim 10 is the invention according to claim 9, wherein a time for rotating the inspection table by the first angle and a time for rotating the inspection table by the second angle are approximately. equal.
According to an eleventh aspect of the present invention, in the invention according to the ninth or tenth aspect, the reference value is a value corresponding to a difference between the first angle and the second angle.

The invention according to claim 12 is the invention according to claim 8, wherein the reference value is a value corresponding to the predetermined angle.
According to a thirteenth aspect of the present invention, in the invention according to the eighth aspect, the reference value is obtained by rotating the reference angular velocity sensor by the predetermined angle on the inspection table. It is a value based on an integrated value of output values output from the reference angular velocity sensor while rotating by an angle.

  The invention described in claim 14 has a measuring step of measuring an offset of the angular velocity sensor in the invention of claim 12 or 13, wherein the output step is performed while rotating by the predetermined angle. A step of outputting a value based on a difference between an integrated value of values output from the angular velocity sensor and an integrated value of offset of the angular velocity sensor output while rotating by the predetermined angle as the first integrated value. It is.

  The invention according to claim 15 is the invention according to claim 12 or 13, wherein the angular velocity sensor offset is removed from the measuring step of measuring the offset of the angular velocity sensor, and the offset of the angular velocity sensor is removed from the output of the angular velocity sensor. An output correction step for correcting the output of the sensor, wherein the output step calculates a value based on an integrated value of the values output from the angular velocity sensor whose output is corrected while rotating by a predetermined angle. This is a step of outputting as an integrated value.

  Further, in the invention described in claim 16, in the invention described in claim 15, the rotating step rotates the inspection table in a predetermined direction by a first angle and in a direction opposite to the predetermined direction. A step of rotating by a second angle, and the output step includes a first integration step of integrating values output from the angular velocity sensor while rotating the inspection table by the first angle, and the angular velocity. A reversing step of reversing the output of the sensor, and a second integrating step of integrating the values output from the angular velocity sensor whose output is inverted while rotating the inspection table by the second angle. The output step outputs a value based on a sum of the integrated value obtained by the first integrating step and the integrated value obtained by the second integrating step as the first integrated value. That is a step.

According to a seventeenth aspect of the present invention, in the invention of the sixteenth aspect, a time for rotating the inspection table by the first angle and a time for rotating the inspection table by the second angle are approximately. equal.
According to an eighteenth aspect of the present invention, in the invention according to the sixteenth or seventeenth aspect, the reference value is a value corresponding to the sum of the first angle and the second angle.

  According to a nineteenth aspect of the present invention, in the invention according to the eighth aspect, the rotating step rotates the inspection table by the predetermined angle T1, and rotates the inspection table by the predetermined angle. In the step of rotating the inspection table by the predetermined angle so that T2 / T1 is 0.7 or less, where T2 is the time during which the inspection table is rotating at a substantially constant angular velocity. is there.

According to the present invention, in order to eliminate the output variation of the angular velocity sensor, the angular velocity sensor output can be calibrated (sensitivity correction) very easily without using a turntable that rotates the angular velocity sensor before shipment at an accurate angular velocity. The angular velocity sensor calibration apparatus and the calibration method thereof can be realized.
Further, since the output during the transition portion of the set angular velocity can also be used, the S / N ratio is improved. Furthermore, since the signal output from the angular velocity sensor is integrated, that is, the angle is used for calibration, the angular velocity sensor used for angle measurement (not angular velocity measurement) can be calibrated with high accuracy.

It is a perspective view for demonstrating the basic principle of the one-dimensional angular velocity sensor using the conventional Coriolis force. (A), (b) is a figure for demonstrating the inspection method of the angular velocity sensor by a vertical motion rotation system. It is a block diagram for demonstrating the calibration apparatus of the angular velocity sensor which concerns on this invention. It is a figure for demonstrating the calibration method of the angular velocity sensor which concerns on this invention. (A), (b) is a figure for demonstrating the sensitivity error in low speed rotation and high speed rotation. (A), (b) is a figure for demonstrating the sensitivity error in the low speed rotation shown to Fig.5 (a). It is a figure which shows the flowchart for demonstrating Example 1 of the calibration method of the angular velocity sensor which concerns on this invention. (A), (b) is a figure for demonstrating the effect by the calibration method of the angular velocity sensor of this invention. It is a figure for demonstrating the necessity of the removal of offset. It is a figure for demonstrating Example 2 (1st method) for solving the problem of the offset shown in FIG. It is a figure which shows the flowchart for demonstrating Example 2 of the calibration method of the angular velocity sensor which concerns on this invention. It is a figure which shows the flowchart for demonstrating the modification of Example 2 of the calibration method of the angular velocity sensor which concerns on this invention. It is a figure for demonstrating Example 3 (2nd method) for solving the problem of the offset shown in FIG. It is a figure for demonstrating Example 4 (3rd method) for solving the problem of the offset shown in FIG.

Embodiments of the present invention will be described below with reference to the drawings.
First, prior to the description of each embodiment of the present invention, a calibration method that is performed without using an angular velocity setting rotational drive method using a conventional turntable that rotates calibration (sensitivity correction) of an angular velocity sensor before shipment, that is, A calibration method using the angle setting rotation drive system will be described below. The angular velocity setting rotational drive is a rotational driving method that performs a circular motion at a constant angular velocity set with respect to the rotation axis. The angle setting rotational driving method is a circle corresponding to the angle set for the rotational axis. It means a rotational drive system that moves.

  2 (a) and 2 (b) are diagrams for explaining an inspection method of an angular velocity sensor by an angle setting rotation drive method, FIG. 2 (a) is a diagram showing the inspection method, and FIG. 2 (b) is an inspection. The waveform diagram of the result is shown. As shown in FIG. 2A, the angular velocity sensor 2 mounted on the flat inspection table 1 is rotated by a set angle about the rotation shaft 1a. That is, the rotation axis of the inspection table 1 is rotated in the A direction (0 to 180 degrees), and then returned to the B direction (180 to 0 degrees). The output from the angular velocity sensor rotated in this way generates an upward rectangular wave and a downward rectangular wave, as shown in FIG.

FIG. 3 is a block diagram for explaining a calibration device for an angular velocity sensor according to the present invention. In the figure, reference numeral 3 denotes an angle setting rotation drive device, 4 denotes an offset measuring unit, 5 denotes an output integration unit (integration processing unit), 6 denotes a reference value storage unit, 7 denotes a sensitivity correction unit, and 8 denotes an angular velocity correction unit. .
The angular velocity sensor calibration apparatus of the present invention is an angular velocity sensor calibration apparatus that corrects the sensitivity of angular velocity output due to the rotational motion of the examination table 1. An angular velocity sensor 2 is mounted on the inspection table 1. In addition, the angle setting rotation drive device 3 rotates the inspection table 1 by a predetermined angle. The output integration unit (integration processing unit) 5 outputs a first integrated value of the values output from the angular velocity sensor 2 during the rotational movement by the angle setting rotation driving device 3.

  The sensitivity correction unit 7 compares the first integrated value by the output integration unit 5 with the reference value stored in the reference value storage unit 6, and corrects the sensitivity of the output of the angular velocity sensor 2 based on the comparison result. Is what you do. The angular velocity correction unit 8 corrects the angular velocity output based on the sensitivity corrected by the sensitivity correction unit 7 and outputs the corrected angular velocity. The offset measuring unit 4 measures the offset of the angular velocity sensor 2.

  The driving device 3 rotates the inspection table 1 in a predetermined direction by a first angle and rotates it in a direction opposite to the predetermined direction by a second angle. A second integrated value of a value output from the angular velocity sensor while rotating by an angle of the second angle, and a third integrated value of a value output from the angular velocity sensor 2 while the inspection table 1 rotates by the second angle; A value based on the difference is output as the first integrated value.

The time for rotating the inspection table 1 by the first angle is substantially equal to the time for rotating the inspection table 1 by the second angle. Further, the reference value is a value corresponding to the difference between the first angle and the second angle.
In addition, although the structure which rotates the inspection table 1 positively / negatively as mentioned above is not essential, if the structure which rotates the inspection table 1 positively / negatively, the inspection table 1 will connect the cable which transmits the signal which the angular velocity sensor 2 outputs. In the case of the configuration, the cable can be prevented from being entangled with the inspection table 1.

  The reference value is a value corresponding to a predetermined angle. The inspection table 1 is rotationally driven. Furthermore, the inspection table 1 may be folded and rotated. By this folding rotation drive, it is not always necessary to return to the original position after the rotation, such as 0 degrees → 180 degrees → 90 degrees, and after the portion of the inspection table on which the angular velocity sensor is mounted is first rotated 180 degrees, The output can be obtained by rotating back to the degree.

With this configuration, the output of the angular velocity sensor can be calibrated (sensitivity correction) very easily without using a turntable that rotates the angular velocity sensor before shipment at an accurate angular velocity in order to eliminate the output variation of the angular velocity sensor. An angular velocity sensor calibration device can be realized.
FIG. 4 is a diagram for explaining the calibration method of the angular velocity sensor according to the present invention. The rectangular wave generated by the angular velocity sensor inspection method by the angle setting rotation driving method shown in FIG. It is a trapezoidal wave used in the method.

The upper row is a rectangular wave generated by the inspection method of the angular velocity sensor by the vertical motion rotation drive system shown in FIG. 2, and the lower row is a trapezoidal wave used in the calibration method of the present invention by integrating the rectangular wave. As shown in the upper part, when V is the output of the angular velocity sensor, S is the sensitivity, and Ωdc is the angular velocity constant, there is a relationship of V = S · Ωdc. Therefore, S = V / Ωdc. On the other hand, in the present invention, from the relationship of ∫Vdt = ∫S · Ωdt,
S = ∫Vdt / ∫Ωdt = ∫Vdt / θ0≈ΣVΔt / θ0 (1)
It becomes. Note that θ0 indicates an angle variation.

  FIGS. 5 (a) and 5 (b) are diagrams for explaining the sensitivity error between low-speed rotation and high-speed rotation. FIG. 5 (b) shows high-speed rotation when FIG. 5 (a) shows low-speed rotation. Shows the case. In the case of the low-speed rotation shown in FIG. 5A, S (sensitivity) is 14.184 (LSB / dps), and the sensitivity error is 1.3%. On the other hand, in the case of the high speed rotation shown in FIG. 5B, S (sensitivity) is 14.170 (LSB / dps), the sensitivity error is 1.4%, and the expected inspection time is 7. 2 sec. It can be seen that the inspection time is shortened because the conventional time is 12 sec.

6A and 6B are diagrams for explaining the sensitivity error in the high-speed rotation shown in FIG. 5B, and FIG. 6A is the diagram shown in FIG. b) shows an angular velocity output with a sensitivity error.
As shown in FIG. 4, the upper stage of FIG. 6 (a) is a rectangular wave generated by the angular velocity sensor inspection method using the angular velocity setting rotational drive system shown in FIG. This is a trapezoidal wave used in the calibration method. The angular velocity output in this case is as shown in the upper part of FIG. 6B because the angular velocity sensor response speed is finite when the angular velocity rapidly increases and rotates in a short time as shown in the upper part of FIG. 6A. As shown, it becomes a dull rectangular wave. When this blunt rectangular wave is integrated, as shown in the lower part of FIG. 6B, only an integrated value smaller than the original integrated value can be obtained, resulting in a sensitivity error.

FIG. 7 is a flowchart for explaining the first embodiment of the calibration method of the angular velocity sensor according to the present invention. The calibration method of the angular velocity sensor of the first embodiment is a calibration method of the angular velocity sensor that performs sensitivity correction of the angular velocity output by the rotational motion of the examination table.
In the first embodiment, first, an angular velocity sensor is mounted on the inspection table 1 (step S1). Next, the inspection table 1 is rotated by a predetermined angle (step S2). Next, the first integrated value of the value output from the angular velocity sensor 2 during the rotational motion is output (step S3). Next, the first integrated value and the reference value are compared, and sensitivity correction of the angular velocity sensor 2 is performed based on the comparison result (step S4).

  The rotation step is a step of rotating the inspection table 1 by a first angle in a predetermined direction and rotating the inspection table 1 by a second angle in a direction opposite to the predetermined direction. A second integrated value of a value output from the angular velocity sensor 2 while rotating by an angle of 1 and a third integrated value of a value output from the angular velocity sensor 2 while the inspection table 1 rotates by a second angle. It is a step of outputting a value based on a difference from the value as a first integrated value.

The time for rotating the inspection table 1 by the first angle is substantially equal to the time for rotating the inspection table 1 by the second angle. Further, the reference value is a value corresponding to the difference between the first angle and the second angle.
The configuration for rotating the inspection table 1 positively or negatively as described above is not essential, but if the configuration for rotating the inspection table 1 positively or negatively is provided, the inspection table 1 includes a cable for transmitting a signal output from the angular velocity sensor 2. In this case, the cable can be prevented from being entangled with the inspection table 1.

  The reference value is, for example, an angle for rotating the inspection table 1 and is a value corresponding to a predetermined angle. That is, the angle at which the inspection table 1 is rotated is set to 180 °, and the value obtained by integrating the values output from the angular velocity sensor 2 while rotating by this predetermined angle is a value corresponding to 175 ° in angle. Then, in this case, calibration is performed by multiplying the output of the angular velocity sensor 2 by (180 ° / 175 °).

  The reference value is the integrated value of the output values output by the reference angular velocity sensor 2 while the reference angular velocity sensor 2 is rotated by a predetermined angle when the reference angular velocity sensor 2 is rotated by a predetermined angle on the inspection table 1. It is a value based on. This is a method of using an integrated value of output values output from the reference angular velocity sensor 2 while the reference angular velocity sensor 2 is rotated by a predetermined angle when the reference angular velocity sensor 2 is rotated by a predetermined angle on the inspection table. .

  That is, the angle at which the examination table is rotated (predetermined angle) is set to 180 °, and the reference angular velocity sensor (reference angular velocity sensor) is placed on the examination table and rotated. The integrated value of the output values output by the angular velocity sensor is a value corresponding to 178 °, and the reference angular velocity sensor is a state in which another angular velocity sensor is placed on the examination table and rotated and rotated by a predetermined angle. Assuming that the integrated value of the output values output by other angular velocity sensors is a value corresponding to 170 °, in this case, calibration is performed by multiplying the output of the other angular velocity sensor by (178 ° / 170 °).

According to such a calibration method of the angular velocity sensor, the following effects can be obtained.
(1) Since the integration process is performed, the calibration time can be shortened with a high SN. (2) The transition portion of the set angular velocity can also be used as a signal, and does not require a constant angular velocity. (3) It is easier to set the angle than to set the angular velocity. (4) Angular accuracy is obtained.
In other words, in order to eliminate the output variation of the angular velocity sensor, the angular velocity sensor output can be calibrated (sensitivity correction) very easily without using a turntable that rotates the angular velocity sensor before shipment at an accurate angular velocity. A calibration method can be realized.

  FIGS. 8A and 8B are diagrams for explaining the effect of the angular velocity sensor calibration method of the present invention, and FIG. 8A shows the angular velocity sensor of the angular setting rotational drive system shown in FIG. A rectangular wave generated by the inspection method is shown when the section of constant angular velocity is long. FIG. 8B shows a case where there is no constant angular velocity section. In the present invention, the sensitivity can be calibrated with high accuracy even using an angular velocity waveform as shown in FIG.

  Since the equation (1) described above is used, if the sensitivity S is obtained in a state where the internal clock cycle Δt is shifted in a certain direction (for example, 90%), an error occurs in the sensitivity of the angular velocity. However, what is often used and important in actual applications is an angle obtained by integrating the angular velocity sensor output. If the angle is obtained by integrating the angular velocity sensor output using the same Δt used at the time of calibration before shipment, the error caused by Δt is canceled and no error occurs in the angle. In addition, since the calibration is performed by setting the angle instead of the angular velocity, the calibration accuracy with respect to the angle is high.

However, there is an offset problem. It is necessary to remove this offset when executing the integration process. That is, in step 4 described above, it is necessary to compare the difference between the output integrated value and the offset value with the reference value.
When the inspection table is rotated by + α ° which is a positive angle, the integrated value of the output of the angular velocity sensor should be + α °. However, when the angular velocity sensor is offset, the integrated value of the output values output from the angular velocity sensor does not become + α °. Specifically, when the signal component of the angular velocity sensor is a, the offset value of the angular velocity sensor is b, and the time taken to rotate the inspection table by a positive angle + α ° is T, the angular velocity sensor outputs. The integrated value of the output value is α + b × T. Therefore, correct calibration cannot be performed unless the offset value is taken into consideration.

FIG. 9 is a diagram for explaining the necessity of removing the offset. The rectangular wave shown in the upper part includes an offset. When this is integrated, a multistage waveform is obtained. That is, it becomes a distorted tilted trapezoidal wave.
FIG. 10 is a diagram for explaining a second embodiment (first method) for solving the offset problem shown in FIG. 9. If the offset is measured in advance and this offset is removed from the rectangular wave including the offset as shown on the left side of FIG. 10, the rectangular wave does not include the offset as shown in the upper right side of FIG. When this rectangular wave is integrated, a trapezoidal wave as shown in the lower right part of FIG. 10 is obtained. The second embodiment is a calibration method in which the offset component of the angular velocity sensor is measured in advance.

FIG. 11 is a flowchart for explaining the second embodiment of the calibration method of the angular velocity sensor according to the present invention.
In the second embodiment, first, an angular velocity sensor is mounted on the inspection table 1 (step S11). Next, the offset of the angular velocity sensor 2 is measured (step S12). Next, the inspection table 1 is rotated by a predetermined angle (step S13). Next, a value based on the difference between the integrated value of the value output from the angular velocity sensor 2 while rotating by a predetermined angle and the integrated value of the offset of the angular velocity sensor 2 output while rotating by a predetermined angle is obtained. The first integrated value is output (step S14). Next, the first integrated value is compared with the reference value, and the sensitivity of the angular velocity sensor is corrected based on the comparison result (step S15).

Assuming that the signal component of the angular velocity sensor 2 is a, the offset component of the angular velocity sensor 2 is b, and the time for rotation by a predetermined angle is T, the output of the angular velocity sensor 2 having the offset component is a + b, and the angular velocity sensor 2 having the offset component The value obtained by integrating the output values is ∫ ₀ ^T (a + b) dt, and the value to be obtained is ∫ ₀ ^T (a) dt.
That is, the offset component b of the angular velocity sensor 2 is measured in advance, the offset component b measured in advance is subtracted from the output a + b of the angular velocity sensor 2 having the offset component, and the difference (that is, a) is integrated at time T. The correct output integrated value (∫ ₀ ^T (a) dt) of the angular velocity sensor 2 is calculated by the method of

FIG. 12 is a flowchart for explaining a modification of the second embodiment of the calibration method of the angular velocity sensor according to the present invention. The modification of the second embodiment is also a calibration method in which the offset component of the angular velocity sensor is measured in advance.
In the modification of the second embodiment, first, an angular velocity sensor is mounted on the inspection table 1 (step S21). Next, the offset of the angular velocity sensor 2 is measured (step S22). Next, the inspection table 1 is rotated by a predetermined angle (step S23). Next, the output of the angular velocity sensor 2 is corrected so as to remove the offset of the angular velocity sensor 2 from the output of the angular velocity sensor 2 (step S24). Next, a value based on the integrated value of the value output from the angular velocity sensor 2 whose output has been corrected during the rotational motion is output as the first integrated value of the angular velocity sensor 2 (step S25). Next, the first integrated value is compared with the reference value, and sensitivity correction of the angular velocity sensor 2 is performed based on the comparison result (step S26).

In this way, the offset component b of the angular velocity sensor 2 is measured in advance, and the integrated value of the offset component ( ^T ₀ ^T (a + b) dt) is obtained by integrating the values output from the angular velocity sensor 2 having the offset component ( ∫ ₀ ^T (b) dt) by subtracting the correct angular velocity sensor 2 outputs the integrated value to calculate the ^{_{(∫ 0 T (a) dt}} ).

FIG. 13 is a diagram for explaining a third embodiment (second method) for solving the problem of the offset illustrated in FIG. 9. The second embodiment shown in FIG. 10 measures the offset in advance, but in the third embodiment, the output of the angular velocity sensor can be accurately integrated even if the offset component of the angular velocity sensor is not measured in advance. The value can be calculated.
As shown in the upper part of FIG. 13, when this offset is removed from a rectangular wave including an offset, a rectangular wave including no offset is obtained. When this rectangular wave is integrated as shown in the lower part of FIG. 13, a waveform shown in the lower part of FIG. 13 is obtained.

  The step of rotating the examination table by a predetermined angle is a step of rotating the examination table by a first angle that is a positive angle + α °, and then rotating it by a second angle that is a negative angle -β °. The step of calculating the output integrated value of the angular velocity sensor during the rotational motion includes the absolute value of the value obtained by integrating the values output from the angular velocity sensor while rotating by the first angle + α °, and the second angle − A value based on a sum of absolute values of values output from the angular velocity sensor while rotating by β ° is integrated and calculated as an integrated output value of the angular velocity sensor. That is, the step of outputting the first integrated value of the value output from the angular velocity sensor during the rotational movement is the second of the values output from the angular velocity sensor while the examination table rotates by the first angle + α °. And a step of outputting a value based on a difference between the integrated value of the first and the third integrated value of the value output from the angular velocity sensor while the inspection table rotates by the second angle −β ° as the first integrated value. is there.

Further, the time for rotating the inspection table by the first angle + α ° is substantially equal to the time for rotating the inspection table by the second angle −β °. The reference value is a value corresponding to an angle of the sum α ° + β ° of the first angle and the second angle.
That is, when the time required to rotate the inspection table by + α ° which is a positive angle is T and the time required to rotate the inspection table by −β ° which is a negative angle is T, the rotation table is positive. A value obtained by integrating the values output from the angular velocity sensor having an offset component while rotating by + α ° which is the angle of α is α + (b × T). A value obtained by integrating the values output from the angular velocity sensor having an offset component while rotating the inspection table by −β ° which is a negative angle is −β + (b × T).

  Accordingly, the difference between the value obtained by integrating the values output from the angular velocity sensor while rotating by the + α ° angle and the value obtained by integrating the values output from the angular velocity sensor while rotating by the −β ° angle is (α + (B × T)) − (− β + (b × T)) = α + β, and the offset component can be eliminated. Note that. α and β may be the same value or different values. Further, in this example, the difference between the integrated values is taken, and since the integrated value of the offset is canceled, there is an effect that the offset measurement is unnecessary.

  FIG. 14 is a diagram for explaining a fourth embodiment (third method) for solving the offset problem shown in FIG. 9. Similar to the third embodiment described above, an accurate angular velocity sensor output integrated value can be calculated without measuring the offset component of the angular velocity sensor in advance. While the third embodiment described above uses the difference between the integrated values, in the fourth embodiment, the value output from the angular velocity sensor is inverted.

The step of rotating the examination table by a predetermined angle is a step of rotating the examination table by a first angle that is a positive angle + α °, and then rotating it by a second angle that is a negative angle -β °. is there.
Further, the step of outputting the first integrated value of the angular velocity sensor during the rotational movement is a first integrating step of integrating the value output from the angular velocity sensor while rotating the inspection table by the first angle + α °. And a step of inverting the output of the angular velocity sensor, a second integration step of integrating the values output from the angular velocity sensor whose output is inverted while the inspection table is rotated by the second angle -β °, and an offset As a first integrated value of the angular velocity sensor, a value based on the sum of the integrated value obtained in the step of correcting the output of the angular velocity sensor so as to eliminate the angular velocity and the integrated value obtained in the second integrating step output from the angular velocity sensor. A step of outputting.

Further, the time for rotating the inspection table by the first angle + α ° is substantially equal to the time for rotating the inspection table by the second angle −β °. The reference value is a value corresponding to an angle of the sum α ° + β ° of the first angle and the second angle.
In the step of rotating the inspection table by a predetermined angle, the time for rotating the inspection table by the predetermined angle is T1, and the inspection table is rotating substantially constant while the inspection table is rotated by the predetermined angle. When the time is T2, the step of rotating the examination table by a predetermined angle so that T2 / T1 is 0.7 or less may be performed. This eliminates the need for precise control of the inspection table and allows the use of an inspection table with less precise angular velocity control. Here, the time during which the examination table is rotated at a substantially constant angular velocity is the angular velocity that is ± 6% of the set angular velocity when the examination table is set to rotate the examination table at a predetermined angular velocity. Refers to the time of day. That is, when the inspection table is set to rotate at M degrees per second, the time during which the inspection table is rotated at an angular velocity of (0.94 M) degrees to (1.06 M) degrees per second is indicated. Smaller T2 / T1 is preferable because precise control of the inspection table becomes unnecessary and an inspection table with less precise angular velocity control can be used. T2 / T1 is preferably 0.6 or less, more preferably 0.5 or less, still more preferably 0.3 or less, and particularly preferably 0.

DESCRIPTION OF SYMBOLS 1 Inspection stand 1a Rotating shaft 2 Angular velocity sensor 3 Vertical rotation motion drive device 4 Offset measurement part 5 Output integration part (integration processing part)
6 Reference value storage unit 7 Sensitivity correction unit 8 Angular velocity correction unit

Claims (19)

An inspection table equipped with an angular velocity sensor;
A driving device for rotating the inspection table by a predetermined angle;
An integration unit for outputting a first integrated value of values output from the angular velocity sensor during the rotational movement;
A sensitivity correction unit that compares the first integrated value with a reference value stored in a storage unit, and performs sensitivity correction of the angular velocity sensor based on the comparison result;
Calibration device for angular velocity sensor comprising: The driving device includes:
The inspection table is rotated by a first angle in a predetermined direction, and rotated by a second angle in a direction opposite to the predetermined direction,
The integrating unit is
A second integrated value of values output from the angular velocity sensor while the inspection table rotates by the first angle, and an output from the angular velocity sensor while the inspection table rotates by the second angle. The angular velocity sensor calibration apparatus according to claim 1, wherein a value based on a difference between a predetermined value and a third integrated value is output as the first integrated value.   The angular velocity sensor calibration apparatus according to claim 2, wherein a time for rotating the inspection table by the first angle is substantially equal to a time for rotating the inspection table by the second angle.   The angular velocity sensor calibration apparatus according to claim 2 or 3, wherein the reference value is a value corresponding to a difference between the first angle and the second angle.   The angular velocity sensor calibration apparatus according to claim 1, further comprising an offset measuring unit that measures an offset of the angular velocity sensor.   The angular velocity sensor calibration apparatus according to claim 1, wherein the reference value is a value corresponding to the predetermined angle.   The angular velocity sensor calibration apparatus according to claim 6, wherein the inspection table is folded and rotated. A mounting step of mounting an angular velocity sensor on the inspection table;
A rotation step for rotating the inspection table by a predetermined angle;
An output step of outputting a first integrated value of values output from the angular velocity sensor during the rotational movement;
A correction step of comparing the first integrated value with a reference value and correcting the sensitivity of the angular velocity sensor based on the comparison result;
Calibration method of angular velocity sensor having The rotation step includes
Rotating the inspection table by a first angle in a predetermined direction and rotating the inspection table by a second angle in a direction opposite to the predetermined direction;
The output step includes
A second integrated value of values output from the angular velocity sensor while the inspection table rotates by the first angle, and an output from the angular velocity sensor while the inspection table rotates by the second angle. 9. The method of calibrating an angular velocity sensor according to claim 8, wherein a value based on a difference between a predetermined value and a third integrated value is output as the first integrated value.   The angular velocity sensor calibration method according to claim 9, wherein a time for rotating the inspection table by the first angle is substantially equal to a time for rotating the inspection table by the second angle.   The angular velocity sensor calibration method according to claim 9 or 10, wherein the reference value is a value corresponding to a difference between the first angle and the second angle.   The angular velocity sensor calibration method according to claim 8, wherein the reference value is a value corresponding to the predetermined angle.   The reference value is an integrated value of output values output by the reference angular velocity sensor while the reference angular velocity sensor is rotated by the predetermined angle when the reference angular velocity sensor is rotated by the predetermined angle on the inspection table. The method of calibrating an angular velocity sensor according to claim 8, wherein the method is a value based on. Measuring step for measuring an offset of the angular velocity sensor;
The output step includes
A value based on a difference between an integrated value of values output from the angular velocity sensor while rotating by the predetermined angle and an integrated value of offset of the angular velocity sensor output while rotating by the predetermined angle; The angular velocity sensor calibration method according to claim 12 or 13, which is a step of outputting the first integrated value. A measurement step of measuring the offset of the angular velocity sensor, and an output correction step of correcting the output of the angular velocity sensor so as to remove the offset of the angular velocity sensor from the output of the angular velocity sensor,
The output step includes
The angular velocity sensor according to claim 12 or 13, wherein the angular velocity sensor is a step of outputting, as the first integrated value, a value based on an integrated value output from the angular velocity sensor that has been output-corrected while rotating by a predetermined angle. Calibration method. The rotation step includes
Rotating the inspection table by a first angle in a predetermined direction and rotating the inspection table by a second angle in a direction opposite to the predetermined direction;
The output step includes
A first integration step of integrating values output from the angular velocity sensor while rotating the inspection table by the first angle; an inversion step of inverting the output of the angular velocity sensor; and A second integration step of integrating the values output from the angular velocity sensor in which the output is inverted while rotating by an angle of 2,
Have
The output step includes
The angular velocity sensor according to claim 15, wherein the angular velocity sensor is a step of outputting a value based on a sum of an integrated value obtained by the first integrating step and an integrated value obtained by the second integrating step as the first integrated value. Calibration method.   The angular velocity sensor calibration method according to claim 16, wherein a time for rotating the inspection table by the first angle is substantially equal to a time for rotating the inspection table by the second angle.   18. The angular velocity sensor calibration method according to claim 16, wherein the reference value is a value corresponding to a sum of the first angle and the second angle.   In the rotation step, T1 is a time for rotating the inspection table by the predetermined angle, and T2 is a time for rotating the inspection table at a substantially constant angular velocity while rotating the inspection table by the predetermined angle. 9. The method of calibrating an angular velocity sensor according to claim 8, wherein the inspection table is rotated by the predetermined angle so that T2 / T1 is 0.7 or less.

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