Sensor device and sensing method

Abstract

To prevent a reduction in detection accuracy due to interference.SOLUTION: A sensor device comprises: two or more detection elements; a storage unit that stores the drive frequencies of the two or more detection elements; and a processing unit that, on the basis of detection signals from the two or more detection elements, acquires a statistical signal obtained by examining statistics on the detection signals, and attenuates, from the statistical signal, an interference signal in a frequency band according to the two or more drive frequencies, and outputs a resultant signal as detection data.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sensor device and a sensing method. [Background technology]

[0002] Conventionally, a sensor device having a plurality of sensor devices is known. For example, Patent Document 1 discloses a sensor device having a plurality of sensor devices. In Patent Document 1, each sensor device is capable of outputting signals related to a plurality of detection axes, and the detection axes are mutually orthogonal. In a sensor device having a plurality of sensor devices, if the detection axes are misaligned, the detection accuracy of a physical quantity may deteriorate. Therefore, in Patent Document 1, correction is performed to align the detection axes of the sensor devices. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-196191 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional technology, the detection accuracy may be reduced due to interference signals caused by using multiple sensor devices. Specifically, when the driving frequencies for driving the detection elements in multiple sensor devices are close to each other, the detection signals output from the sensor devices may interfere with each other, causing noise and reducing the detection accuracy. [Means for solving the problem]

[0005] A sensor device as one embodiment for solving the above problem includes two or more detection elements, a memory unit that stores the drive frequencies of the two or more detection elements, and a processing unit that acquires a statistical signal by calculating the detection signals based on the detection signals from the two or more detection elements, and attenuates interference signals in a frequency band corresponding to the two or more drive frequencies from the statistical signal and outputs the interference signals as detection data.

[0006] A sensor device as one embodiment for solving the above problem includes two or more detection elements, and a processing unit that acquires a statistical signal by computing detection signals from the two or more detection elements, and attenuates interference signals below a predetermined frequency from the statistical signal and outputs the resulting signal as detection data.

[0007] In a sensing method as one embodiment for solving the above problem, a statistical signal is obtained by statistically computing detection signals from two or more detection elements, and interference signals in a frequency band corresponding to the drive frequencies of the two or more detection elements that have been stored in advance are attenuated from the statistical signal and output as detection data. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a block diagram showing a configuration example of a sensor device. [Diagram 2] FIG. 1 is a block diagram showing an example of the configuration of a sensor device. [Diagram 3] 6 is a flowchart illustrating a process in a processing unit. [Figure 4] FIG. 4 is a diagram showing an example of a drive frequency. [Diagram 5] FIG. 11 is a diagram showing an example of a difference in drive frequency. [Figure 6] FIG. 1 shows an example of the configuration of a second-order IIR filter. [Figure 7] FIG. 4 is a diagram showing an example of a drive frequency. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A preferred embodiment of the present invention will be described in detail below. Note that the present embodiment described below does not limit the content of the present invention described in the claims, and all of the configurations described in the present embodiment are not necessarily essential as a means for solving the problem of the present invention.

[0010] (1) First embodiment Fig. 1 is a block diagram showing the configuration of a sensor device 10 according to the present embodiment. As shown in Fig. 1, the sensor device 10 includes a first sensor device 20a, a second sensor device 20b, and a third sensor device 20c, a processing unit 30, a communication circuit 40, and a storage device 50.

[0011] The communication circuit 40 is a circuit for communication between the sensor device 10 and an external device, and is electrically connected to a connection terminal between the sensor device 10 and the external device. The communication circuit 40 is capable of performing various types of communication, and for example, outputs detection data acquired by the processing unit 30 through processing described below to the external device.

[0012] The processing unit 30 functions as a matching processing unit 30a, a statistical processing unit 30b, and a filter processing unit 30c. The processing unit 30 may be realized by various circuits, and various logic operation circuits such as an MCU (Micro Controller Unit) and an application specific integrated circuit (ASIC) can be adopted as circuits constituting at least a part of the processing unit 30. In this embodiment, a configuration is assumed in which the MCU of the processing unit 30 performs digital processing on the digital signal output from the sensor device. However, the processing unit 30 may include a processing circuit such as an A / D converter, and the analog signal output from the sensor device may be converted to a digital signal by the processing unit 30 for processing.

[0013] The storage device 50 is a non-volatile storage device such as a semiconductor memory. The storage device 50 stores correction coefficients for executing a matching process described later. The correction coefficients include correction coefficients such as a rotation matrix described later that are used when correcting at least two or all three of the first sensor device 20a, the second sensor device 20b, and the third sensor device 20c. Each correction coefficient is stored in association with the sensor device to be corrected.

[0014] Furthermore, in this embodiment, the storage device 50 includes filter setting data that can be applied to an IIR (Infinite Impulse Response) filter 31, which will be described later. The IIR filter 31, which will be described later, functions as a band-stop filter that attenuates various frequency bands. A plurality of frequency bands are set, and filter coefficients for realizing a band-stop filter for each frequency band are specified in advance and stored in the storage device 50 as filter setting data in association with the frequency band. Note that the processing unit 30 and the storage device 50 may be configured as an integrated piece of hardware, or may be configured as separate pieces of hardware.

[0015] The first sensor device 20a, the second sensor device 20b, and the third sensor device 20c are sensor devices having the same configuration. Fig. 2 is a diagram showing the configuration of these sensor devices. Since the first sensor device 20a, the second sensor device 20b, and the third sensor device 20c have a common configuration, when they are not explicitly distinguished from each other, the first sensor device 20a, the second sensor device 20b, and the third sensor device 20c may be simply called sensor devices.

[0016] 2, the sensor devices (20a, 20b, 20c) include a first detection element 21, a second detection element 22, a third detection element 23, a correction circuit 24, a communication interface (I / F) 25, and a storage unit 26. The communication I / F 25 is electrically connected to a processing unit 30.

[0017] The first detection element 21, the second detection element 22, and the third detection element 23 are elements that detect the physical quantities of the first axis, the second axis, and the third axis, which are orthogonal to each other. The physical quantities are not limited, but here, elements that detect angular acceleration are assumed. The first axis, the second axis, and the third axis only need to be orthogonal to each other, and these axes may also be called the X-axis, the Y-axis, and the Z-axis.

[0018] Each of the first detection element 21, the second detection element 22, and the third detection element 23 detects angular acceleration around an axis perpendicular to the surface on which the element is mounted. Each of the first detection element 21, the second detection element 22, and the third detection element 23 is mounted on a substrate (not shown) so as to be perpendicular to each other, and is configured so that the axes of angular acceleration are perpendicular to each other.

[0019] In this embodiment, the first sensor device 20a, the second sensor device 20b, and the third sensor device 20c each include a first detection element 21, a second detection element 22, and a third detection element 23. The first sensor device 20a, the second sensor device 20b, and the third sensor device 20c each can detect angular acceleration about three axes, the X-axis, the Y-axis, and the Z-axis.

[0020] Therefore, each of the first sensor device 20a, the second sensor device 20b, and the third sensor device 20c includes a first detection element 21 that outputs a detection signal for detecting a physical quantity of the same axis, the X-axis. Furthermore, each of the first sensor device 20a, the second sensor device 20b, and the third sensor device 20c includes a second detection element 22 that outputs a detection signal for detecting a physical quantity of the same axis, the Y-axis. Furthermore, each of the first sensor device 20a, the second sensor device 20b, and the third sensor device 20c includes a third detection element 23 that outputs a detection signal for detecting a physical quantity of the same axis, the Z-axis.

[0021] Furthermore, the first sensor device 20a includes a first detection element 21, a second detection element 22, and a third detection element 23 that output detection signals for detecting physical quantities of different axes. Moreover, the second sensor device 20b includes a first detection element 21, a second detection element 22, and a third detection element 23 that output detection signals for detecting physical quantities of different axes. The third sensor device 20c includes a first detection element 21, a second detection element 22, and a third detection element 23 that output detection signals for detecting physical quantities of different axes.

[0022] The first sensor device 20a, the second sensor device 20b, and the third sensor device 20c are all designed to have a common axis for detecting angular acceleration. However, due to misalignment of each element when mounted on a substrate, the X-axis, Y-axis, and Z-axis of a detection element of a certain sensor device may be slightly deviated from being orthogonal to each other. For example, in a certain sensor device, the X-axis, which is the detection axis of the first detection element 21, and the Y-axis, which is the detection axis of the second detection element 22, may be slightly deviated from being orthogonal to each other.

[0023] In addition, the same axis may be slightly misaligned between the detection elements of different sensor devices. For example, the X-axis, which is the detection axis of the first detection element 21 in the first sensor device 20a, and the X-axis, which is the detection axis of the first detection element 21 in the second sensor device 20b, may be slightly misaligned from parallel. For this reason, this embodiment is provided with a configuration for correcting errors due to such misalignment.

[0024] In this specification, correcting errors due to misalignment of detector elements within a single sensor device is referred to as an intra-sensor correction process, and correcting errors due to misalignment of detector elements between different sensor devices is referred to as an alignment process.

[0025] The storage unit 26 is a storage device that stores various information. In this embodiment, the information stored in the storage unit 26 includes various parameters used when the correction circuit 24 performs the in-sensor correction process, and the drive frequency of the detection elements. The parameters include correction coefficients such as a rotation matrix described later that are used when correcting at least two or all of the first detection element 21, the second detection element 22, and the third detection element 23. Each correction coefficient is stored in association with the detection element to be corrected.

[0026] The drive frequency is a frequency at which the first detection element 21, the second detection element 22, and the third detection element 23 included in the sensor device are driven. Since the drive frequency depends on the natural frequency of the elements included in the first detection element 21, the second detection element 22, and the third detection element 23, the drive frequencies may differ slightly even for elements manufactured according to the same design. Therefore, in this embodiment, the drive frequencies of the first detection element 21, the second detection element 22, and the third detection element 23 are measured in advance and stored in the storage unit 26.

[0027] The first detection element 21, the second detection element 22, and the third detection element 23 output analog detection signals indicating physical quantities related to the respective detection axes to the correction circuit 24. The correction circuit 24 converts the analog detection signals into digital detection signals by an A / D converter (not shown). Then, the correction circuit 24 corrects the signals obtained by digitally converting the detection signals output from the first detection element 21, the second detection element 22, and the third detection element 23 so that the multiple detection axes are mutually orthogonal. Specifically, the correction circuit 24 refers to the storage unit 26 and acquires correction coefficients such as a rotation matrix stored as parameters for correction. Then, the correction circuit 24 applies the correction coefficients associated with each detection element to each of the detection signals output from the first detection element 21, the second detection element 22, and the third detection element 23 to perform a correction process within the sensor. The correction may include correction of an offset error and a scale factor error included in the detection signal. When the detection signal is corrected, the corrected detection signal is output to the processing unit 30 via the communication I / F 25.

[0028] Returning to FIG. 1, the explanation will be continued. The processing in the processing unit 30 is started when a predetermined condition (e.g., the passage of a predetermined period of time) is satisfied after the start of power supply to the sensor device 10. The processing in the processing unit 30 is executed according to the flowchart shown in FIG. 3. When the processing is started, the processing unit 30 acquires detection signals from each sensor device (step S100). That is, the first sensor device 20a, the second sensor device 20b, and the third sensor device 20c output digital detection signals indicating physical quantities detected for each of the X-axis, Y-axis, and Z-axis. The processing unit 30 acquires the detection signals for each axis transmitted from each sensor device via an interface (not shown).

[0029] Next, the processing unit 30 executes a matching process by the matching processing unit 30a (step S105). Specifically, the matching processing unit 101 executes a matching process to correct an error caused by misalignment of detection elements between different sensor devices. The correction is performed by multiplying the detection signal output from the sensor device to be corrected by a correction coefficient stored in the storage device 50.

[0030] For example, when performing correction to align the detection axis of the first sensor device 20a with the detection axis of the second sensor device 20b, the alignment processing unit 30a applies a correction coefficient associated with the first sensor device 20a to the detection signal from the first sensor device 20a. In this case, the correction coefficient is a coefficient for eliminating misalignment of the first sensor device 20a with respect to the second sensor device 20b. The correction coefficient is also a coefficient for rotating the detection axis of the first sensor device 20a so as to match the detection axis of the second sensor device 20b as a reference. The correction coefficient may be any one of a rotation matrix, an Euler angle, and a quaternion.

[0031] In this case, the matching processing unit 30a further performs matching processing by applying a correction coefficient associated with the third sensor device 20c to the detection signal from the third sensor device 20c. In this case, the correction coefficient is a coefficient for eliminating misalignment of the third sensor device 20c with respect to the second sensor device 20b. In addition, the correction coefficient is a coefficient for rotating the detection axis of the third sensor device 20c so as to match the detection axis of the second sensor device 20b as a reference. Here, the correction coefficient may be any one of a rotation matrix, an Euler angle, and a quaternion.

[0032] Of course, the above alignment process is just one example, and the reference when the alignment process is performed may be a sensor device other than the second sensor device 20b, or a correction may be made to align all of the first sensor device 20a, the second sensor device 20b, and the third sensor device 20c with an arbitrary reference.

[0033] Next, the processing unit 30 executes statistical processing by the statistical processing unit 30b (step S110). Specifically, the statistical processing unit 30b acquires statistical signals by taking statistics of the detection signals after the matching processing is performed by the matching processing unit 30a, based on the detection signals. That is, the statistical processing unit 30b takes statistics of the signals after the matching processing is performed on the detection signals from the first sensor device 20a, the second sensor device 20b, and the third sensor device 20c. The statistics may be performed by various methods, but in this embodiment, it is an averaging process.

[0034] The averaging process is a process for improving the statistical accuracy of the physical quantity of each axis. Therefore, it is performed for each axis. Specifically, the statistical processing unit 30b obtains an average of detection signals from different sensor devices for the same axis. For example, a signal equivalent to the average of the detection signal from the first detection element 21 of the first sensor device 20a, the detection signal from the first detection element 21 of the second sensor device 20b, and the detection signal from the first detection element 21 of the third sensor device 20c is obtained as a statistical signal. The statistics are performed for each axis. As a result of the above, statistical signals are obtained for each of the X-axis, Y-axis, and Z-axis. In general, when statistics are obtained based on N samples, the noise is reduced to 1 / N 1 / 2 Therefore, when two or more sensor devices are used, the statistical accuracy can be improved compared to when fewer sensor devices are used.

[0035] Next, the processing unit 30 performs filtering by the filter processing unit 30c (steps S115 to S130). Specifically, the filter processing unit 30c attenuates interference signals in frequency bands corresponding to two or more driving frequencies from the statistical signal and outputs the attenuated signals as detection data. That is, the filter processing unit 30c removes interference signals caused by using different driving frequencies by filtering.

[0036] The statistical signal acquired by the statistical processing unit 30b as described above may include an interference signal. The interference signal is generated by driving the detection element at different driving frequencies, and may occur at each frequency corresponding to the difference and sum of two driving frequencies selected from any driving frequencies. However, in this embodiment, the frequency corresponding to the sum of the driving frequencies is in a frequency band different from the frequency band of the statistical signal handled by the processing unit 30, and may be removed by a filter or the like (not shown), so it is not subject to filtering by the filter processing unit 30c. That is, in this embodiment, the filter processing unit 30c attenuates signals in a frequency band including the difference between two or more driving frequencies.

[0037] Furthermore, even if the frequency corresponds to the difference between any two drive frequencies, the signal components with small power spectrum density and the frequencies that can be removed by a filter (not shown) provided separately from the filter processing unit 30c (for example, a filter that extracts only the statistical signal used for detection) may not be processed by the filter processing unit 30c. In this embodiment, an interference signal in a frequency band relatively close to the frequency band of the signal used as the statistical signal is processed by the filter processing unit 30c.

[0038] 4 shows the drive frequencies of the first detection element 21 (X-axis), the second detection element 22 (Y-axis), and the third detection element 23 (Z-axis) of the first sensor device 20a, the second sensor device 20b, and the third sensor device 20c in this embodiment. In this embodiment, if the axis is the same even for different sensor devices, the difference in drive frequency is relatively small, and if the axis is different even for the same sensor device, the difference in drive frequency is relatively large. For example, the drive frequencies of the first detection element 21 of the second sensor device 20b and the third sensor device 20c are 49366 Hz and 49128 Hz, as shown in FIG. 4, and the difference between the two is 238 Hz.

[0039] On the other hand, the drive frequencies of the first detection element 21 and the second detection element 22 of the second sensor device 20b are 49366 Hz and 50658 Hz, respectively, and the difference between the two is 1292 Hz, as shown in Fig. 4. In this embodiment, the difference between the drive frequencies of the detection elements on the same axis is smaller than 1000 Hz, and the difference between the drive frequencies of the detection elements on different axes is larger than 1000 Hz.

[0040] 5 is a diagram showing the absolute value of the difference between the drive frequencies of the detection elements on the same axis. Δ12 indicates the difference between the drive frequency of the detection element of the first sensor device 20a and the drive frequency of the detection element of the second sensor device 20b. Δ23 indicates the difference between the drive frequency of the detection element of the second sensor device 20b and the drive frequency of the detection element of the third sensor device 20c, and Δ31 indicates the difference between the drive frequency of the detection element of the third sensor device 20c and the drive frequency of the detection element of the first sensor device 20a.

[0041] In this embodiment, interference signals exceeding 1000 Hz can be removed by a filter (not shown) provided separately from the filter processing unit 30c, and are therefore not subject to processing by the filter processing unit 30c. On the other hand, interference signals lower than 1000 Hz are subject to processing by the filter processing unit 30c.

[0042] That is, in this embodiment, the drive frequencies of the detector elements are selected so that interference signals that may occur between detector elements of the same axis can be processed by the filter processing unit 30c, and interference signals that may occur between detector elements of different axes do not need to be processed by the filter processing unit 30c. Therefore, in this embodiment, the filter processing unit 30c attenuates interference signals in frequency bands corresponding to the drive frequencies of the detector elements that detect physical quantities of the same axis from the statistical signal and outputs them as detection data.

[0043] Specifically, the filter processing unit 30c acquires the drive frequencies from each sensor device (step S115). That is, the filter processing unit 30c acquires the drive frequencies of the first detection element 21 to the third detection element 23 from the storage unit 26 of the first sensor device 20a, and acquires the drive frequencies of the first detection element 21 to the third detection element 23 from the storage unit 26 of the second sensor device 20b. Furthermore, the filter processing unit 30c acquires the drive frequencies of the first detection element 21 to the third detection element 23 from the storage unit 26 of the third sensor device 20c.

[0044] Next, the filter processing unit 30c acquires the difference of the driving frequency (step S120). In this embodiment, in order to remove interference signals generated in relation to the detection elements that detect the physical quantity of the same axis, the filter processing unit 30c acquires the difference for each axis. Specifically, the filter processing unit 30c acquires the absolute value of the difference for all combinations obtained by extracting two from the driving frequency of the first detection element 21 in the first sensor device 20a, the driving frequency of the first detection element 21 in the second sensor device 20b, and the driving frequency of the first detection element 21 in the third sensor device 20c. For example, in the case of the X-axis shown in FIG. 4, the filter processing unit 30c acquires Δ12, Δ23, and Δ31 for the X-axis shown in FIG. 5. The filter processing unit 30c similarly acquires the difference for all combinations for the Y-axis and Z-axis. In the example shown in FIG. 4, all the differences shown in FIG. 5 are acquired.

[0045] In order to attenuate an interference signal having a frequency corresponding to the difference, the filter processing unit 30c can perform band-stop filtering (or notch filtering). Although such digital filtering may be realized by various configurations, in this embodiment, the digital filtering is realized by a second-order IIR filter 31 shown in FIG.

[0046] The second-order IIR filter 31 includes adders 311-314, delayers 315 and 316, and multipliers 317-3111. The delayers 315 and 316 provide a unit delay to the input signal and output the result. The multipliers 317-3111 multiply the input signal by a coefficient and output the result. The coefficients of the multipliers 317-3111 are a11, a21, b01, b11, and b21 shown in FIG. 6 for the multipliers 317-3111, respectively. The adders 311-314 add the codes shown in FIG. 6 to the input signals, add them, and output the results.

[0047] 6, adder unit 311 adds the input signal and a signal obtained by making the fed-back signal a negative signal, and outputs the result. The signal output from adder unit 311 is delayed by delay units 315 and 316. The signal delayed by delay unit 315 is input to multiplier units 317 and 3110 and delay unit 316. The signal delayed by delay unit 316 is input to multiplier units 318 and 3111.

[0048] The signals input to multipliers 317 and 318 are multiplied by coefficients a11 and a21, the results are added by adder 312, and the result is input to adder 311. The signals input to multipliers 3110 and 3111 are multiplied by filter coefficients b11 and b21, the results are added by adder 314, and the result is input to adder 313. Adder 313 receives as input a signal that has been multiplied by filter coefficient b01 by multiplier 319, and is the output of adder 311. Adder 313 outputs the sum of both input signals.

[0049] The above-described second-order IIR filter 31 can be made to have various characteristics by adjusting the filter coefficients b01, b11, b21, a11, and a21. In this embodiment, in order to perform parallel filtering on the statistical signals for the X-axis, Y-axis, and Z-axis, three second-order IIR filters 31 that receive the statistical signals for each axis are provided in parallel.

[0050] In this embodiment, the filter processing unit 30c specifies filter coefficients so that each second-order IIR filter 31 becomes a band-stop filter that stops a desired frequency band. That is, the storage device 50 stores filter coefficients for realizing a band-stop filter that attenuates a frequency band in association with the frequency band.

[0051] Therefore, the filter processing unit 30c performs a process of acquiring a filter coefficient associated with a frequency band including the difference acquired in step S120 for each axis. For example, in the example shown in Fig. 5, when acquiring a filter coefficient for the X-axis, the filter processing unit 30c selects a frequency band in which the low-frequency cutoff frequency fcl of the band-stop filter is smaller than the minimum difference value 15 and the high-frequency cutoff frequency fch is larger than the maximum difference value 253. When there are multiple selectable frequency bands, the filter processing unit 30c selects, for example, the narrowest frequency band.

[0052] When a frequency band is selected, the filter processing unit 30c refers to the storage device 50 and acquires the filter coefficients b01, b11, b21, a11, and a21 associated with the selected frequency band. The filter processing unit 30c performs similar processing for the Y-axis and Z-axis to determine the filter coefficients for each axis. With the above configuration, it is possible to easily set a filter that removes interference signals with a frequency corresponding to the drive frequency.

[0053] Next, the filter processing unit 30c applies the filter coefficients to the second-order IIR filter 31 (step S130). That is, the filter processing unit 30c applies the filter coefficients for each axis acquired in step S125 to each of the second-order IIR filters 31 corresponding to each axis. According to the above configuration, each of the second-order IIR filters 31 corresponding to each axis functions as a band-stop filter that attenuates each of the interference signals that may occur for each axis.

[0054] The processing unit 30 uses the digital signal after attenuating the interference signal as detection data, and outputs the detection data to an external device via the communication circuit 40. With the above configuration, the external device can obtain physical quantities along each axis using the statistical signal from which the interference signal has been removed. Therefore, the physical quantities can be obtained without being affected by the interference signal, and the detection accuracy of the physical quantities can be prevented from decreasing.

[0055] In addition, in this embodiment, an interference signal to be removed occurs in a frequency band corresponding to the drive frequency of a detection element that detects a physical quantity of the same axis. In this embodiment, a filter process is performed on the interference of signals related to the same axis, but a filter process is not performed on the interference of signals related to different axes. Therefore, compared to a configuration in which a filter process is performed on the interference of signals related to different axes, the influence of the interference signal can be removed by a simple process.

[0056] (2) Other embodiments The above-described embodiment is an example for carrying out the present invention, and various embodiments can be adopted. For example, the frequency of the interference signal to be removed by the filter processing unit 30c is a relatively small frequency (1000 Hz or less in the above-described embodiment), but of course, an interference signal of any frequency may be processed by the filter processing unit 30c. Furthermore, the sensor device may be used for various purposes. For example, it may be used in various electronic devices and in-vehicle devices. Examples of in-vehicle devices include various navigation devices and automatic driving control devices. Furthermore, it may be used in a positioning device that measures the position of a vehicle.

[0057] Furthermore, in the above embodiment, the interference signal having a frequency corresponding to the difference between the drive frequencies for detecting the physical quantity of the same axis is filtered, but the present invention is not limited to such a configuration. For example, the filter processing unit 30c may be configured to attenuate the interference signal having a frequency band corresponding to the drive frequency of each of the detection elements for detecting the physical quantities of different axes from the statistical signal and output the attenuated interference signal as the detection data.

[0058] 7 is an example showing the drive frequencies of the first detection element 21, the second detection element 22, and the third detection element 23 included in the first sensor device 20a, the second sensor device 20b, and the third sensor device 20c, respectively. In this example, the difference in drive frequencies of the detection elements in the same sensor device is relatively small, and the difference in drive frequencies of the detection elements between different sensor devices is relatively large.

[0059] In this example, the frequency corresponding to the difference in drive frequencies of detection elements within the same sensor device is the frequency that should be removed in the filter processing unit 30c, and the frequency corresponding to the difference in drive frequencies of detection elements between different sensor devices is not the frequency that should be removed in the filter processing unit 30c.

[0060] In this case, the statistical signals for each of the X-axis, Y-axis, and Z-axis may contain interference signals of frequencies to be removed. Therefore, the filter processing unit 30c applies a band-stop filter to each of the statistical signals for each axis, which attenuates the frequency band including the frequencies to be removed. With the above configuration, it is possible to remove interference signals generated by driving detection elements in the same sensor device at similar driving frequencies from the statistical signals, and it is possible to prevent the detection accuracy from being reduced by interference signals.

[0061] Furthermore, if a sensor device having a detection element for detecting physical quantities of the first axis, the second axis, and the third axis is regarded as a set of sensor devices, the above-mentioned first sensor device 20a, the second sensor device 20b, and the third sensor device 20c can be regarded as three sets of sensor devices. In this configuration, the filter processing unit 30c may be configured to attenuate an interference signal in a frequency band corresponding to each driving frequency of any detection element from the statistical signal and output it as detection data. For example, when a frequency corresponding to the difference between the driving frequencies of any two detection elements is relatively small and is a frequency to be removed in the filter processing unit 30c, a band-stop filter is operated to attenuate the frequency band including the difference. According to the above configuration, an interference signal generated by driving any detection element at a close driving frequency can be removed from the statistical signal, and it is possible to prevent the detection accuracy from being reduced by the interference signal.

[0062] Furthermore, when it is clear that the difference in the driving frequencies is equal to or less than a predetermined frequency, for example, the specifications of the detection elements are within a planned range, and if the detection elements have specifications within the planned range, the difference in the driving frequencies is equal to or less than a predetermined frequency. In this case, the processing unit 30 may be configured to obtain a statistical signal by statistically calculating the detection signals based on the detection signals from two or more detection elements, and to attenuate interference signals having a frequency equal to or less than a predetermined frequency from the statistical signal and output the signals as detection data. With the above configuration, it is possible to prevent a decrease in detection accuracy due to interference signals without performing a process of obtaining the difference in the driving frequencies. Of course, with this configuration, the driving frequencies of the above-mentioned detection elements do not need to be stored in the storage unit.

[0063] The detection element may be an element that detects a physical quantity, and the physical quantity to be detected is not limited to the angular acceleration described above, but may be various quantities, such as angular velocity, acceleration, speed, distance, pressure, sound pressure, magnetic quantity, etc.

[0064] The storage unit is required only to store the driving frequency of the detection element, but of course, other information may be stored therein. Since the driving frequency of the detection element may differ for each detection element, the storage unit stores the driving frequency for driving each detection element. The storage unit in which the driving frequency is stored may be present in the sensor device 10.

[0065] The processing unit only needs to acquire a statistical signal by calculating the detection signals based on the detection signals from two or more detection elements, and attenuate interference signals in frequency bands corresponding to two or more drive frequencies from the statistical signal and output the signal as detection data. That is, the processing unit uses the detection signals from two or more detection elements to improve the statistical accuracy of the detection signals and acquire the statistical signal. Also, the processing unit only needs to attenuate interference signals from the statistical signal to obtain the detection data.

[0066] The detection signal may be a signal indicating a physical quantity detected by a detection element, and may be a signal that has been subjected to various corrections, etc. The statistical signal may be a signal obtained by statistically calculating the detection signal. That is, the processing unit may use a plurality of detection signals to obtain a statistical signal indicating a physical quantity with higher accuracy than a single detection signal. The statistical method is not limited to the averaging described above, and various statistics may be performed. For example, a mode, a median, or the like may be obtained based on a plurality of detection signals to be used as a statistical signal.

[0067] The interference signal is a signal generated by two or more detection elements being used in close proximity to each other, and is a signal in a frequency band according to the drive frequency. Therefore, the interference signal may change according to the drive frequency. Therefore, the processing unit determines the frequency band of the interference signal according to the drive frequency stored in the storage unit, and performs filtering to attenuate the interference signal in the frequency band.

[0068] A filter that attenuates a signal in a specific frequency band can be realized by various configurations. For example, the above-mentioned IIR filter is not limited to the configuration shown in FIG. 6, and may be realized by various known configurations. For example, a second-order or higher IIR filter may be used, IIR filters may be connected in series, or a FIR (Finite Impulse Response) filter or the like may be used. Furthermore, when the statistical signal or the like is an analog signal, filtering may be performed by an analog filter with a variable frequency band.

[0069] The frequency band may be a band that includes an interference signal, and for example, as in the above-described embodiment, the frequency of the interference signal is estimated by the difference in the driving frequencies. Therefore, the processing unit may attenuate the frequency band that includes the frequency. When the sensor device includes three or more detection elements, there are a plurality of combinations of any two detection elements, and the frequency band may be determined so that the difference between the driving frequencies is included for all of these combinations, or the frequency band may be determined so that the difference between the driving frequencies is included for some of the combinations. For example, when the difference between the driving frequencies is equal to or less than a threshold value, the frequency band may be configured so that the frequency of the difference is included in the frequency band, and when the difference between the driving frequencies is greater than the threshold value, the frequency band may be configured so that the frequency of the difference is not included in the frequency band. As the latter, for example, an interference signal that can be attenuated by using a filter different from the filter for attenuating the interference signal may be attenuated by using the filter. [Explanation of symbols]

[0070] 10...sensor device, 15...minimum value, 20a...first sensor device, 20b...second sensor device, 20c...third sensor device, 21...first detection element, 22...second detection element, 23...third detection element, 24...correction circuit, 25...communication I / F, 26...storage unit, 30...processing unit, 30a...matching processing unit, 30b...statistical processing unit, 30c...filter processing unit, 31...second-order IIR filter, 40...communication circuit, 50...storage device, 101...matching processing unit, 253...maximum value, 311...addition unit, 312...addition unit, 313...addition unit, 314...addition unit, 315...delay unit, 316...delay unit, 317...multiplication unit, 318...multiplication unit, 319...multiplication unit, 3110...multiplication unit, 3111...multiplication unit

Claims

1. Two or more detection elements; A storage unit that stores drive frequencies of two or more of the detection elements; A processing unit that acquires a statistical signal by calculating the detection signals based on the detection signals from two or more of the detection elements, and attenuates an interference signal in a frequency band corresponding to two or more of the drive frequencies from the statistical signal and outputs the attenuated interference signal as detection data; A sensor device comprising:

2. each of the two or more detection elements includes a detection element that outputs the detection signal for detecting a physical quantity of the same axis; The processing unit includes: the interference signal in a frequency band corresponding to the drive frequency of each of the detection elements detecting the physical quantity of the same axis is attenuated from the statistical signal and output as the detection data. The sensor device of claim 1 .

3. Each of the two or more detection elements includes a detection element that outputs the detection signal for detecting a physical quantity of a different axis, The processing unit includes: the interference signal in a frequency band corresponding to the drive frequency of each of the detection elements detecting the physical quantities of the different axes is attenuated from the statistical signal and output as the detection data. The sensor device of claim 1 .

4. Each of the two or more detection elements includes a plurality of sets of the detection elements that detect physical quantities of a first axis, a second axis, and a third axis that are orthogonal to each other; The processing unit includes: the interference signal in a frequency band corresponding to the driving frequency of each of the arbitrary detection elements is attenuated from the statistical signal and output as the detection data; The sensor device of claim 1 .

5. The frequency band is: A band including a difference between two or more of the drive frequencies, The sensor device of claim 1 .

6. Two or more detection elements; a processing unit that acquires a statistical signal by statistically calculating the detection signals based on the detection signals from two or more of the detection elements, and attenuates an interference signal having a frequency equal to or lower than a predetermined frequency from the statistical signal and outputs the attenuated signal as detection data; A sensor device comprising:

7. a statistical signal is obtained by computing the detection signals based on the detection signals from two or more detection elements, and an interference signal in a frequency band corresponding to the drive frequencies of the two or more detection elements that is stored in advance is attenuated from the statistical signal and output as detection data; Sensing method.

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