Sensor module

Abstract

To provide a sensor module that can suppress a decrease in detection accuracy even if the correction of the characteristics of each of the multiple inertial sensors is insufficient. [Solution] A sensor module comprising: a first sensor device including a first inertial sensor having a first detection axis, a second detection axis and a third detection axis and outputting a first signal; and a first correction unit that corrects predetermined characteristics of the first signal based on first correction information to generate a first correction signal; a second sensor device including a second inertial sensor having a fourth detection axis, a fifth detection axis and a sixth detection axis and outputting a second signal; and a second correction unit that corrects predetermined characteristics of the second signal based on second correction information to generate a second correction signal; a synthesis processing unit that synthesizes a first detection signal based on the first correction signal and a second detection signal based on the second correction signal to generate a composite signal; and a correction processing unit that corrects predetermined characteristics of the composite signal based on third correction information.

Description

Technical Field

[0001] The present invention relates to a sensor module.

Background Art

[0002] Patent Document 1 discloses a first sensor module including a first inertial sensor and a first correction circuit that generates a first correction signal by correcting a first signal output from the first inertial sensor so that a plurality of detection axes of the first inertial sensor are orthogonal to each other; a second sensor module including a second inertial sensor and a first correction circuit that generates a second correction signal by correcting a second signal output from the second inertial sensor so that a plurality of detection axes of the second inertial sensor are orthogonal to each other; an alignment processing unit that generates a first alignment signal by applying a first correction coefficient for aligning a plurality of detection axes of the first inertial sensor with a reference axis to the first correction signal, and generates a second alignment signal by applying a second correction coefficient for aligning a plurality of detection axes of the second inertial sensor with the reference axis to the second correction signal; and a synthesis processing unit that synthesizes and outputs the first alignment signal and the second correction signal. According to the inertial sensor device described in Patent Document 1, the deviation between the plurality of detection axes of the first inertial sensor and the plurality of detection axes of the second inertial sensor is corrected, so the detection accuracy is improved. Further, the noise component can be reduced by synthesizing the first alignment signal and the second correction signal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the inertial sensor device described in Patent Document 1, the first correction circuit further corrects the offset error and scale factor error of the first inertial sensor, and the second correction circuit further corrects the offset error and scale factor error of the second inertial sensor. However, if these corrections are insufficient, the detection accuracy may decrease. [Means for solving the problem]

[0005] One aspect of the sensor module according to the present invention is: A first sensor device comprising: a first inertial sensor having a first detection axis, a second detection axis, and a third detection axis and outputting a first signal; and a first correction unit that corrects predetermined characteristics of the first signal based on first correction information and generates a first correction signal; A second sensor device comprising: a second inertial sensor having a fourth detection axis, a fifth detection axis, and a sixth detection axis and outputting a second signal; and a second correction unit that corrects the predetermined characteristics of the second signal based on second correction information to generate a second correction signal; A synthesis processing unit that generates a composite signal by combining a first detection signal based on the first correction signal and a second detection signal based on the second correction signal, A correction processing unit that corrects the predetermined characteristics of the composite signal based on the third correction information, It holds. [Brief explanation of the drawing]

[0006] [Figure 1] Perspective view of the sensor module. [Figure 2] A plan view of the inside of the sensor module. [Figure 3] Disassembled perspective view of the sensor module. [Figure 4] Decomposed perspective view of the IMU. [Figure 5] Top view of the circuit board. [Figure 6] Bottom view of the circuit board. [Figure 7] Functional block diagram of the sensor module. [Figure 8] IMU functional block diagram. [Figure 9] A diagram showing an example of the temperature characteristics of the first detection signal, the second detection signal, and the combined signal. [Figure 10] A figure showing another example of the temperature characteristics of the first detection signal, the second detection signal, and the combined signal. [Figure 11] A figure showing an example of the temperature characteristics of the composite signal and the signal obtained by correcting the composite signal in the first embodiment. [Figure 12] This figure shows another example of the temperature characteristics of the composite signal and the signal obtained by correcting the composite signal in the first embodiment. [Figure 13] This figure shows an example of the temperature characteristics of the composite signal and the signal obtained by correcting the composite signal in the second embodiment. [Modes for carrying out the invention]

[0007] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. The embodiments described below are not intended to unduly limit the scope of the present invention as described in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

[0008] 1. First Embodiment 1-1. Structure of the sensor module Figures 1 to 3 show the structure of the sensor module 1 of this embodiment. Figure 1 is a perspective view of the sensor module 1. Figure 2 is a plan view of the inside of the sensor module 1. Figure 3 is an exploded perspective view of the sensor module 1.

[0009] As shown in FIGS. 1 to 3, the sensor module 1 of the present embodiment includes, for example, a substrate 10, inertial measurement units (IMUs) 2A, 2B, 2C mounted on the substrate 10, a processing circuit 100, and a container 9. The sensor module 1 defines three axes of an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other, and detects accelerations in the directions of the three axes and angular velocities around the three axes. The sensor module 1 detects the motion states of, for example, moving objects such as vehicles, robots, and drones, electronic devices such as smartphones and tablet terminals, and various other objects. The motion states include, for example, position, orientation, velocity, acceleration, angular velocity, and the like. Hereinafter, for convenience of explanation, the direction along the X-axis is also referred to as the "X-axis direction", the direction along the Y-axis is also referred to as the "Y-axis direction", and the direction along the Z-axis is also referred to as the "Z-axis direction".

[0010] As shown in FIGS. 1 and 2, the container 9 includes a base 91 having a recess 911 that opens upward, and a lid 92 that is fixed to the base 91 so as to close the opening of the recess 911. The container 9 is generally in the shape of a rectangular flat plate. The base 91 and the lid 92 define an accommodation space S inside the recess 911 that is sealed by the lid 92. The accommodation space S is a space for accommodating components such as the substrate 10, the IMUs 2A, 2B, 2C, and the processing circuit 100. The container 9 protects the components accommodated in the accommodation space S from dust, moisture, ultraviolet rays, impacts, and the like.

[0011] The base 91 and the lid 92 may be made of aluminum (Al). In addition, as the materials of the base 91 and the lid 92 respectively, for example, metal materials such as Al alloys, zinc (Zn), stainless steel, various ceramics, various resin materials, and composite materials thereof can be adopted.

[0012] The sensor module 1 includes a connector 93 attached to the side wall of the base 91 and a communication substrate 931 disposed in the accommodation space S. The connector 93 is a receptacle that makes an electrical connection between the inside and the outside of the container 9. The communication substrate 931 has a circuit that processes communication between the sensor module 1 and other devices.

[0013] The substrate 10 is a circuit board including various elements and wirings. The substrate 10 mounts the IMUs 2A, 2B, 2C, the processing circuit 100, the internal connector 110, etc. The substrate 10 is fixed, for example, relative to the base 91.

[0014] As shown in FIGS. 2 and 3, the IMUs 2A, 2B are arranged along the X-axis on the lower surface of the substrate 10. The IMU 2C is arranged on the upper surface of the substrate 10 so as to overlap the IMU 2A when viewed from the direction along the Z-axis. The processing circuit 100 and the internal connector 110 are arranged on the upper surface of the substrate 10 so as to overlap the IMU 2B when viewed from the direction along the Z-axis. Thus, by efficiently arranging various components with respect to the area of the substrate 10 and the accommodation space S, miniaturization of the sensor module 1 can be achieved.

[0015] The IMUs 2A, 2B, 2C are connected to the processing circuit 100 via the substrate 10. The processing circuit 100 controls the driving of the IMUs 2A, 2B, 2C. The processing circuit 100 is connected to the communication substrate 931 via the internal connector 110 and wirings (not shown) connected to the internal connector 110.

[0016] The IMUs 2A, 2B, 2C have, for example, similar structures to each other. Hereinafter, any one of the IMUs 2A, 2B, 2C is simply referred to as "IMU2", and redundant explanations are omitted. The number of IMUs 2 is not limited to three, and may be two or four or more.

[0017] Figure 4 is an exploded perspective view of the IMU 2. As shown in Figure 4, the IMU 2 comprises an outer case 21, an inner case 22, a connecting member 23, and a circuit board 24. The outer case 21 has a recess into which the inner case 22 is inserted. The outer case 21 and the inner case 22 are joined to each other by the connecting member 23 while housing and holding the circuit board 24. The IMU 2 is square when viewed from above, i.e., along the c-axis as shown in Figure 4. The outer case 21 has, for example, screw holes 211, 212 provided at each of a pair of diagonally opposite corners on the top surface. The sensor module 1 can be fixed to the substrate 10 by being screwed using the screw holes 211, 212.

[0018] Figure 5 is a top view of the circuit board 24, and Figure 6 is a bottom view of the circuit board 24. As shown in Figures 5 and 6, the circuit board 24 is equipped with a module connector 25, angular velocity sensors 26a, 26b, 26c, an acceleration sensor 27, a correction circuit 28, etc. The module connector 25 connects the IMU 2 and the board 10. The module connector 25 is exposed to the board 10 through an opening 221 provided in the inner case 22, for example. The angular velocity sensor 26a detects the angular velocity ωa around the a-axis. The angular velocity sensor 26b detects the angular velocity ωb around the b-axis. The angular velocity sensor 26c detects the angular velocity ωc around the c-axis. The acceleration sensor 27 detects the acceleration Aa along the a-axis, the acceleration Ab along the b-axis, and the acceleration Ac along the c-axis, respectively. The a-axis, b-axis, and c-axis are defined for each IMU 2. In the following explanation, for the sake of clarity, the direction along the a-axis will also be referred to as the "a-axis direction," the direction along the b-axis as the "b-axis direction," and the direction along the c-axis as the "c-axis direction."

[0019] The correction circuit 28 is composed of, for example, an integrated circuit (IC). The correction circuit 28 is connected to the angular velocity sensors 26a, 26b, 26c and the acceleration sensor 27 via the circuit board 24. The correction circuit 28 is connected to the processing circuit 100 via the circuit board 24, module connector 25, board 10, etc.

[0020] The circuit board 24 is, for example, square in shape when viewed from a direction along the c-axis. When the four quadrants defined around the center O of the circuit board 24 are called the first quadrant Q1, the second quadrant Q2, the third quadrant Q3, and the fourth quadrant Q4, the acceleration sensor 27 is placed in the first quadrant Q1. As shown in Figure 3, the IMUs 2A, 2B, and 2C are arranged so that their respective first quadrants Q1 are close to each other.

[0021] Specifically, in the example shown in Figure 3, the acceleration sensor 27A of IMU2A and the acceleration sensor 27C of IMU2C are arranged to overlap each other when viewed from the direction along the Z axis. The acceleration sensor 27A of IMU2A and the acceleration sensor 27B of IMU2B are arranged to overlap each other when viewed from the direction along the X axis. This makes it possible to minimize the difference in acceleration received by each of the acceleration sensors 27A, 27B, and 27C.

[0022] The module connector 25 is located on the upper surface 241 of the circuit board 24 in the second quadrant Q2 and the third quadrant Q3. The angular velocity sensor 26a is located on the side of the circuit board 24 in the fourth quadrant Q4. The angular velocity sensor 26b is located on the side of the circuit board 24 in the first quadrant Q1. The angular velocity sensor 26c is located on the upper surface 241 of the circuit board 24 in the fourth quadrant Q4. The acceleration sensor 27 is located on the upper surface 241 of the circuit board 24 in the first quadrant Q1. The correction circuit 28 is located on the lower surface 242 of the circuit board 24 in the third quadrant Q3. The screw hole 211 is located in the second quadrant Q2, and the screw hole 212 is located in the fourth quadrant Q4.

[0023] As shown in Figure 3, the a-axis direction of IMU2A corresponds to the -Y-axis direction, the b-axis direction of IMU2A corresponds to the +X-axis direction, and the c-axis direction of IMU2A corresponds to the +Z-axis direction. Similarly, the a-axis direction of IMU2B corresponds to the -X-axis direction, the b-axis direction of IMU2B corresponds to the -Y-axis direction, and the c-axis direction of IMU2B corresponds to the +Z-axis direction. Furthermore, the a-axis direction of IMU2C corresponds to the +X-axis direction, the b-axis direction of IMU2C corresponds to the -Y-axis direction, and the c-axis direction of IMU2C corresponds to the -Z-axis direction.

[0024] 1-2. Functional configuration of the sensor module Figure 7 is a functional block diagram of the sensor module 1. As shown in Figure 7, the sensor module 1 includes IMUs 2A, 2B, and 2C, a processing circuit 100, a communication interface circuit 90, and a storage unit 3.

[0025] IMU2A, 2B, and 2C use the a, b, and c axes as detection axes and detect acceleration in these three axes and angular velocity around these axes. The functional configuration of IMU2A, 2B, and 2C is the same, and Figure 8 shows the functional block of IMU2, which is one of IMU2A, 2B, or 2C.

[0026] As shown in Figure 8, the IMU2 includes an inertial sensor 20, a correction circuit 28, a memory unit 30, and a communication interface circuit 31.

[0027] The inertial sensor 20 includes angular velocity sensors 26a, 26b, and 26c and an acceleration sensor 27. The angular velocity sensor 26a detects the angular velocity around the a-axis, which is the detection axis, and outputs a signal corresponding to the detected angular velocity. The angular velocity sensor 26b detects the angular velocity around the b-axis, which is the detection axis, and outputs a signal corresponding to the detected angular velocity. The angular velocity sensor 26c detects the angular velocity around the c-axis, which is the detection axis, and outputs a signal corresponding to the detected angular velocity. The acceleration sensor 27 detects acceleration in the a-axis direction, acceleration in the b-axis direction, and acceleration in the c-axis direction, which are the detection axes, and outputs a signal corresponding to the detected 3-axis acceleration. The angular velocity sensors 26a, 26b, and 26c and the acceleration sensor 27 may be sensors using MEMS or sensors using quartz. MEMS is an abbreviation for Micro Electro Mechanical Systems.

[0028] The correction circuit 28 corrects predetermined characteristics of the signal output from the inertial sensor 20 based on the correction information 301 stored in the memory unit 30 to generate a corrected signal. The signal output from the inertial sensor 20 includes signals output from angular velocity sensors 26a, 26b, and 26c, respectively, and signals output from the acceleration sensor 27. The predetermined characteristics are, for example, temperature characteristics, linearity, or sensitivity characteristics. Temperature characteristics are characteristics that show the deviation of the output of the inertial sensor 20 with respect to temperature. Linearity is a characteristic that shows the error from an ideal straight line representing the relationship between the input and output of the inertial sensor 20. Sensitivity characteristics are characteristics that show the rate of change of the output with respect to the input of the inertial sensor 20.

[0029] The communication interface circuit 31 is a circuit that performs interface processing between the IMU 2 and the processing circuit 100. The communication interface circuit 31 outputs, for example, a correction signal generated by the correction circuit 28 to the processing circuit 100. Examples of communication standards between the IMU 2 and the processing circuit 100 include SPI and UART. SPI is an abbreviation for Serial Peripheral Interface, and UART is an abbreviation for Universal Asynchronous Receiver Transmitter.

[0030] The memory unit 30 includes a non-volatile memory for storing various programs and predetermined data, and a RAM for storing correction signals generated by the correction circuit 28. RAM stands for Random Access Memory. In particular, the memory unit 30 stores correction information 301. Correction information 301 is information for correcting the temperature characteristics, linearity, sensitivity characteristics, etc., of the signal output from the inertial sensor 20, and is created during the inspection process of the IMU 2 and stored in the non-volatile memory of the memory unit 30 in advance. The RAM is also used as a working area for the correction circuit 28 and stores programs and data read from the non-volatile memory, as well as data temporarily generated by the correction circuit 28.

[0031] Returning to the explanation of Figure 7, the processing circuit 100 performs various calculation processes and control processes for the communication interface circuit 90. The processing circuit 100 includes a matching processing unit 101, a synthesis processing unit 102, and a correction processing unit 103. The processing circuit 100 may function as the matching processing unit 101, the synthesis processing unit 102, and the correction processing unit 103 by executing a program (not shown) stored in the storage unit 3. Alternatively, the matching processing unit 101, the synthesis processing unit 102, and the correction processing unit 103 may be implemented in hardware.

[0032] The matching processing unit 101 generates a detection signal by matching the a-axis, b-axis, and c-axis to the mutually orthogonal X-axis, Y-axis, and Z-axis with respect to the correction signals output from IMUs 2A, 2B, and 2C, respectively, based on the matching information 4 stored in the memory unit 3.

[0033] Specifically, the matching processing unit 101 generates a first detection signal by matching the b-axis direction to the +X-axis direction, the a-axis direction to the -Y-axis direction, and the c-axis direction to the +Z-axis direction with respect to the first correction signal output from IMU2A, based on the matching information 4. The matching processing unit 101 also generates a second detection signal by matching the a-axis direction to the -X-axis direction, the b-axis direction to the -Y-axis direction, and the c-axis direction to the +Z-axis direction with respect to the second correction signal output from IMU2B, based on the matching information 4. The matching processing unit 101 also generates a third detection signal by matching the a-axis direction to the +X-axis direction, the b-axis direction to the -Y-axis direction, and the c-axis direction to the -Z-axis direction with respect to the third correction signal output from IMU2C, based on the matching information 4. The matching information 4 may include a first rotation matrix that transforms the b-axis, a-axis, and c-axis directions of IMU2A into the +X-axis, -Y-axis, and +Z-axis directions, respectively; a second rotation matrix that transforms the a-axis, b-axis, and c-axis directions of IMU2B into the -X-axis, -Y-axis, and +Z-axis directions, respectively; and a third rotation matrix that transforms the a-axis, b-axis, and c-axis directions of IMU2C into the +X-axis, -Y-axis, and -Z-axis directions, respectively.

[0034] The synthesis processing unit 102 generates a combined signal by combining the first detection signal, the second detection signal, and the third detection signal. For example, the synthesis processing unit 102 may generate a combined signal by averaging the first detection signal, the second detection signal, and the third detection signal.

[0035] If the X-axis angular velocity signals, Y-axis angular velocity signals, and Z-axis angular velocity signals included in the composite signal are denoted as imuData.gx, imuData.gy, and imuData.gz, respectively, then imuData.gx, imuData.gy, and imuData.gz are calculated by equations (1) to (3), respectively. In equations (1) to (3), imuData[A].ga, imuData[A].gb, and imuData[A].gc are the a-axis angular velocity signals, b-axis angular velocity signals, and c-axis angular velocity signals included in the first detection signal, respectively. Also, imuData[B].ga, imuData[B].gb, and imuData[B].gc are the a-axis angular velocity signals, b-axis angular velocity signals, and c-axis angular velocity signals included in the second detection signal, respectively. Furthermore, imuData[C].ga, imuData[C].gb, and imuData[C].gc are the a-axis angular velocity signal, b-axis angular velocity signal, and c-axis angular velocity signal included in the third detection signal, respectively.

[0036]

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[0037]

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[0038]

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[0039] Similarly, if the X-axis acceleration signal, Y-axis acceleration signal, and Z-axis acceleration signal included in the composite signal are denoted as imuData.ax, imuData.ay, and imuData.az, respectively, then imuData.ax, imuData.ay, and imuData.az are calculated by equations (4) to (6), respectively. In equations (4) to (6), imuData[A].aa, imuData[A].ab, and imuData[A].ac are the a-axis acceleration signal, b-axis acceleration signal, and c-axis acceleration signal included in the first detection signal, respectively. Also, imuData[B].aa, imuData[B].ab, and imuData[B].ac are the a-axis acceleration signal, b-axis acceleration signal, and c-axis acceleration signal included in the second detection signal, respectively. Furthermore, imuData[C].aa, imuData[C].ab, and imuData[C].ac are the a-axis acceleration signal, b-axis acceleration signal, and c-axis acceleration signal included in the third detection signal, respectively.

[0040]

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[0041]

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[0042]

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[0043] The synthesis processing of the synthesis processing unit 102 reduces random noise to 1 / √3, improving the signal-to-noise ratio of the synthesized signal.

[0044] The correction processing unit 103 corrects predetermined characteristics of the composite signal output from the composite processing unit 102 based on the correction information 5 stored in the memory unit 3. Specifically, the correction processing unit 103 corrects predetermined characteristics of the X-axis angular velocity signal, Y-axis angular velocity signal, Z-axis angular velocity signal, X-axis acceleration signal, Y-axis acceleration signal, and Z-axis acceleration signal included in the composite signal. These predetermined characteristics may be, for example, temperature characteristics, linearity, or sensitivity characteristics.

[0045] The arithmetic processing unit 104 performs known calculations on the X-axis angular velocity signal, Y-axis angular velocity signal, Z-axis angular velocity signal, X-axis acceleration signal, Y-axis acceleration signal, and Z-axis acceleration signal after correction by the correction processing unit 103 to calculate the position, attitude, velocity, etc. of the sensor module 1.

[0046] The communication interface circuit 90 is a circuit that performs interface processing between the processing circuit 100 and an external device (not shown). The communication interface circuit 90 outputs data calculated by the processing circuit 100 to the external device, for example. Examples of communication standards between the processing circuit 100 and the external device include SPI and UART. The communication interface circuit 90 is mounted on a communication board 931, for example.

[0047] The memory unit 3 includes a non-volatile memory for storing various programs and predetermined data, and a RAM for storing data generated by the processing circuit 100. In particular, the memory unit 3 stores correction information 5. Correction information 5 is information for correcting the temperature characteristics, linearity, sensitivity characteristics, etc., of the composite signal output from the synthesis processing unit 102, and is created during the inspection process of the sensor module 1 and stored in the non-volatile memory of the memory unit 3 in advance. The RAM is also used as a workspace for the processing circuit 100 and stores programs and data read from the non-volatile memory, as well as data temporarily generated by the processing circuit 100.

[0048] 1-3. Correction process The combined signal output from the synthesis processing unit 102 is a combination of the first detection signal, the second detection signal, and the third detection signal. Therefore, variations in the characteristics of each of the first, second, and third detection signals are reduced. As an example, the temperature characteristics of the combined signal will be used to explain this. In the following, for the sake of simplicity in illustration and explanation, only the first and second detection signals will be combined. In reality, the signals to be combined are the angular velocity signals or acceleration signals of each axis contained in the first and second detection signals, respectively. However, in the following, the signals to be combined will simply be referred to as the "first detection signal" and the "second detection signal," and the signal obtained by combining these signals will simply be referred to as the "combined signal."

[0049] Figure 9 shows an example of the temperature characteristics of the first detection signal, the second detection signal, and the combined signal. In Figure 9, the series of black circles shows the temperature characteristics of the first detection signal, the series of black triangles shows the temperature characteristics of the second detection signal, and the series of white circles shows the temperature characteristics of the combined signal. The first detection signal is generated based on the first correction signal, whose temperature characteristics have been corrected in IMU2A, and the second detection signal is generated based on the second correction signal, whose temperature characteristics have been corrected in IMU2B. Therefore, as shown in Figure 9, in the range of -40°C to +80°C, the deviations of the first and second detection signals are small, but the deviation of the combined signal is even smaller.

[0050] However, depending on the data acquisition conditions used to create the correction information 5 stored in the respective memory units 3 of IMU2A and 2B, it is conceivable that the deviation of the first detection signal or the second detection signal may be large, and the deviation of the combined signal may not be sufficiently small. For example, as shown in Figure 10, at +10°C and +60°C, the second detection signal, indicated by the black-filled triangle, has a value far removed from other temperatures, indicating a large deviation in the second detection signal. For example, if the temperature characteristics of the inertial sensor 20 of IMU2b have singularities at +10°C and +60°C, and the correction information 301 is created using data acquired at five temperature points: -40°C, -10°C, +20°C, +50°C, and +80°C, the data at the singularities of +10°C and +60°C will not be reflected in the correction information 301. As a result, the temperature characteristics of the second detection signal will be as shown in Figure 10, and the deviation of the combined signal will not be sufficiently small.

[0051] Therefore, in this embodiment, as described above, the correction processing unit 103 further corrects the composite signal based on the correction information 5. Figure 11 shows an example of the temperature characteristics of the composite signal and the signal after the composite signal has been corrected. In Figure 11, the series of black triangles shows the temperature characteristics of the composite signal, and the series of white circles shows the temperature characteristics of the signal after the composite signal has been corrected. Also, in the example of Figure 11, both the correction information 301 and the correction information 5 are created using data acquired at five temperature points: -40°C, -10°C, +20°C, +50°C, and +80°C. In the example of Figure 11, the difference Δ2 between the maximum and minimum values ​​of the signal after the composite signal has been corrected is smaller than the difference Δ1 between the maximum and minimum values ​​of the composite signal, but Δ1 and Δ2 are not significantly different. The reason for this is that the temperatures at which the data used to create the correction information 5 was acquired are the same as the temperatures at which the data used to create the correction information 301 was acquired, so the data at singular points such as +10°C and +60°C are not reflected in the correction information 301. In other words, if the data acquisition conditions used to create the correction information 5 are the same as the data acquisition conditions used to create the respective correction information 301 for IMUs 2A, 2B, and 2C, then the improvement in characteristics due to the correction by the correction processing unit 103 is not zero, but it is not significant.

[0052] Therefore, it is preferable that the data acquisition conditions used to create the correction information 5 differ from the data acquisition conditions used to create the respective correction information 301 for IMU2A, 2B, and 2C. The data acquisition conditions are the temperature at which the data is acquired when creating correction information 5 to correct temperature characteristics, and the input angular velocity and acceleration when creating correction information 5 to correct linearity or sensitivity characteristics.

[0053] Figure 12 shows an example of the temperature characteristics of the composite signal and the signal after correcting the composite signal when the data acquisition conditions used to create correction information 5 are different from the data acquisition conditions used to create correction information 301. In Figure 12, the series of black triangles shows the temperature characteristics of the composite signal, and the series of white circles shows the temperature characteristics of the signal after correcting the composite signal. In the example in Figure 12, data acquired at five temperature points -40°C, -10°C, +20°C, +50°C, and +80°C is used to create correction information 301, and data acquired at four temperature points -30°C, +10°C, +30°C, and +70°C is used to create correction information 5. In the example in Figure 12, the difference Δ2 between the maximum and minimum values ​​of the signal after correcting the composite signal is smaller than the difference Δ1 between the maximum and minimum values ​​of the composite signal, indicating a significant improvement in the temperature characteristics.

[0054] Furthermore, in order to enhance the effect of the correction processing unit 103 on improving the characteristics, it is preferable that data acquired under the conditions of singularities that are degrading the characteristics is used to create the correction information 5. For example, in the evaluation of the IMU2, conditions of singularities that are degrading the characteristics may be identified, and the correction information 5 may be created using multiple data sets, including data acquired under those conditions.

[0055] Furthermore, the higher the order of correction in the correction processing unit 103, the easier it is to improve the characteristics of the corrected signal from the composite signal. Therefore, the order of correction in the correction processing unit 103 may be higher than the order of correction in the respective correction circuits 28 of IMUs 2A, 2B, and 2C. For correction, polynomials used for interpolation and approximation in numerical analysis and function approximation are used. The order of correction refers to the order of these polynomials.

[0056] Furthermore, it is preferable that at least one of the a-axis, b-axis, and c-axis directions of IMU2A differs from any of the a-axis, b-axis, and c-axis directions of IMU2B, and also differs from any of the a-axis, b-axis, and c-axis directions of IMU2C. Similarly, it is preferable that at least one of the a-axis, b-axis, and c-axis directions of IMU2B differs from any of the a-axis, b-axis, and c-axis directions of IMU2A, and also differs from any of the a-axis, b-axis, and c-axis directions of IMU2C. Similarly, it is preferable that at least one of the a-axis, b-axis, and c-axis directions of IMU2C differs from any of the a-axis, b-axis, and c-axis directions of IMU2A, and also differs from any of the a-axis, b-axis, and c-axis directions of IMU2B.

[0057] In this embodiment, as shown in Figure 3, the b-axis direction of IMU2A is the a-axis direction of IMU2B, and is different from the a-axis, b-axis, and c-axis directions of IMU2B. Also, the c-axis direction of IMU2A is the -c-axis direction of IMU2C, and is different from the a-axis, b-axis, and c-axis directions of IMU2C. Also, the a-axis direction of IMU2B is the -b-axis direction of IMU2A, and is different from the a-axis, b-axis, and c-axis directions of IMU2A. Also, the a-axis direction of IMU2B is the -a-axis direction of IMU2C, and is different from the a-axis, b-axis, and c-axis directions of IMU2C. Also, the c-axis direction of IMU2B is the -c-axis direction of IMU2C, and is different from the a-axis, b-axis, and c-axis directions of IMU2C. Also, the c-axis direction of IMU2C is the -a-axis direction of IMU2A, and is different from the a-axis, b-axis, and c-axis directions of IMU2A. Furthermore, the a-axis direction of IMU2C is the -a-axis direction of IMU2B, and is different from the a-axis, b-axis, and c-axis directions of IMU2B. Also, the c-axis direction of IMU2C is the -c-axis direction of IMU2B, and is different from the a-axis, b-axis, and c-axis directions of IMU2B.

[0058] In this way, since the orientations of IMU2A, 2B, and 2C are different from each other, the singularities of the characteristics of each inertial sensor 20 tend to be different from each other, and the characteristic deviation can be reduced by the synthesis processing of the synthesis processing unit 102.

[0059] Note that IMU2A is an example of a "first sensor device," and IMU2B is an example of a "second sensor device." The inertial sensor 20 of IMU2A is an example of a "first inertial sensor," and the inertial sensor 20 of IMU2B is an example of a "second inertial sensor." The detection axes a, b, and c of the inertial sensor 20 of IMU2A are examples of the "first detection axis," "second detection axis," and "third detection axis," respectively, and the detection axes a, b, and c of the inertial sensor 20 of IMU2B are examples of the "fourth detection axis," "fifth detection axis," and "sixth detection axis," respectively. The X, Y, and Z axes of sensor module 1 are examples of the "first reference axis," "second reference axis," and "third reference axis," respectively. The signal output from the inertial sensor 20 of IMU2A is an example of a "first signal," and the signal output from the inertial sensor 20 of IMU2B is an example of a "second signal." The correction circuit 28 of IMU2A is an example of a "first correction unit," and the correction circuit 28 of IMU2B is an example of a "second correction unit." The correction signal output from the correction circuit 28 of IMU2A is an example of a "first correction signal," and the correction signal output from the correction circuit 28 of IMU2B is an example of a "second correction signal." The correction information 301 of IMU2A is an example of "first correction information," the correction information 301 of IMU2B is an example of "second correction information," and the correction information 5 is an example of "third correction information."

[0060] 1-4. Effects As described above, according to the sensor module 1 of the first embodiment, the synthesis processing unit 102 synthesizes the first detection signal, the second detection signal, and the third detection signal generated by the matching processing unit 101 to generate a composite signal, thereby reducing random noise included in the composite signal. Furthermore, even if the correction of predetermined characteristics of the signals output from at least one inertial sensor 20 of IMU 2A, 2B, and 2C is insufficient, and the deviation of at least one of the first correction signal, the second correction signal, and the third correction signal is relatively large, the synthesis processing unit 102 further corrects the predetermined characteristics of the composite signal, thereby suppressing a decrease in detection accuracy.

[0061] In particular, if the data acquisition conditions used to create the correction information 5 are different from the data acquisition conditions used to create the respective correction information 301 of IMUs 2A, 2B, and 2C, it becomes easier to correct singularities that worsen the predetermined characteristics of the composite signal, thereby further suppressing the decrease in detection accuracy.

[0062] Furthermore, according to the sensor module 1 of the first embodiment, the alignment processing unit 101 corrects the misalignment between the a-axis, b-axis, and c-axis of IMU2A, the a-axis, b-axis, and c-axis of IMU2B, and the a-axis, b-axis, and c-axis of IMU2C, thereby suppressing a decrease in detection accuracy.

[0063] 2. Second Embodiment In the following description of the second embodiment, the same reference numerals are used for components similar to those in the first embodiment, and explanations that overlap with those in the first embodiment will be omitted or simplified. The main points to be described will be those that differ from the first embodiment.

[0064] The structure of the sensor module 1 in the second embodiment is the same as in Figures 1 to 3, so its illustration and description are omitted. Similarly, the structure of the IMU 2 in the second embodiment is the same as in Figures 4 to 6, so its illustration and description are omitted. Furthermore, the functional configuration of the sensor module 1 in the second embodiment is the same as in Figure 7, so its illustration and description are omitted. However, in the second embodiment, the method for creating the correction information 5 differs from that of the first embodiment.

[0065] In this embodiment, the number of data points used to create the correction information 5 is greater than the number of data points used to create the correction information 301 for each of the IMUs 2A, 2B, and 2C. Therefore, the acquisition conditions for at least some of the data used to create the correction information 5 will differ from the acquisition conditions for the data used to create the correction information 301, making it easier for data with singularities that worsen the characteristics to be reflected in the correction information 5.

[0066] Figure 13 shows an example of the temperature characteristics of the composite signal and the signal after correcting the composite signal when the number of data used to create correction information 5 is greater than the number of data used to create correction information 301. In Figure 13, the series of black triangles shows the temperature characteristics of the composite signal, and the series of white circles shows the temperature characteristics of the signal after correcting the composite signal. In the example in Figure 13, five data points acquired at five temperature points -40°C, -10°C, +20°C, +50°C, and +80°C are used to create correction information 301, and nine data points acquired at nine temperature points -40°C, -30°C, -10°C, +10°C, +20°C, +30°C, +50°C, +70°C, and +80°C are used to create correction information 5. In the example in Figure 13, the difference Δ2 between the maximum and minimum values ​​of the signal after correcting the composite signal is smaller than the difference Δ1 between the maximum and minimum values ​​of the composite signal, indicating a significant improvement in the temperature characteristics.

[0067] In this embodiment as well, in order to enhance the effect of improving the characteristics through the correction of the correction processing unit 103, it is preferable that data acquired under the conditions of singularities that worsen the characteristics is used to create the correction information 5. For example, in the evaluation of IMU2, conditions of singularities that worsen the characteristics may be identified, and correction information 5 may be created using multiple data sets including data acquired under those conditions. Furthermore, the order of correction of the correction processing unit 103 may be greater than the order of correction of each correction circuit 28 of IMU2A, 2B, and 2C. In addition, it is preferable that at least one of the a-axis, b-axis, and c-axis directions of IMU2A is different from any of the a-axis, b-axis, and c-axis directions of IMU2B, and also different from any of the a-axis, b-axis, and c-axis directions of IMU2C. Similarly, it is preferable that at least one of the a-axis, b-axis, and c-axis directions of IMU2B is different from any of the a-axis, b-axis, and c-axis directions of IMU2A, and also different from any of the a-axis, b-axis, and c-axis directions of IMU2C. Similarly, it is preferable that at least one of the a-axis, b-axis, and c-axis directions of IMU2C is different from any of the a-axis, b-axis, and c-axis directions of IMU2A, and also different from any of the a-axis, b-axis, and c-axis directions of IMU2B.

[0068] The other configurations of the sensor module 1 in the second embodiment are the same as those of the sensor module 1 in the first embodiment, so their description will be omitted.

[0069] As explained above, according to the sensor module 1 of the second embodiment, the number of data used to create the correction information 5 is greater than the number of data used to create the correction information 301 of each IMU 2A, 2B, and 2C. Therefore, it becomes easier to correct singularities that worsen the predetermined characteristics of the composite signal, and the decrease in detection accuracy can be further suppressed.

[0070] Furthermore, the sensor module 1 of the second embodiment provides the same effects as the sensor module 1 of the first embodiment.

[0071] 3. Variant The present invention is not limited to this embodiment, and various modifications can be implemented within the scope of the gist of the present invention.

[0072] For example, in each of the embodiments described above, the sensor module 1 has three IMUs 2, but the number of IMUs 2 in the sensor module 1 is not particularly limited and may be two, four or more.

[0073] Furthermore, in each of the above embodiments, the inertial sensor 20 of the IMU2 has angular velocity sensors 26a, 26b, and 26c for detecting three-axis angular velocity and an accelerometer 27 for detecting three-axis acceleration. However, it is not necessary to have the angular velocity sensors 26a, 26b, and 26c, nor is it necessary to have the accelerometer 27. In addition, the inertial sensor 20 of the IMU2 may have other sensors in addition to the angular velocity sensors 26a, 26b, and 26c and the accelerometer 27.

[0074] Furthermore, in each of the embodiments described above, the orientations of the detection axes of IMU2A, 2B, and 2C are different from each other, but the orientations of two or three of the detection axes of IMU2A, 2B, and 2C may be the same.

[0075] The embodiments and variations described above are examples only and are not limited thereto. For example, each embodiment and each variation can be combined as appropriate.

[0076] The present invention includes configurations substantially identical to those described in the embodiments, for example, configurations with the same function, method, and results, or configurations with the same purpose and effect. Furthermore, the present invention includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as those described in the embodiments. Finally, the present invention includes configurations that add known technology to the configurations described in the embodiments.

[0077] The following can be derived from the embodiments and modifications described above.

[0078] One embodiment of a sensor module is: One aspect of the sensor module according to the present invention is: A first sensor device comprising: a first inertial sensor having a first detection axis, a second detection axis, and a third detection axis and outputting a first signal; and a first correction unit that corrects predetermined characteristics of the first signal based on first correction information and generates a first correction signal; A second sensor device comprising: a second inertial sensor having a fourth detection axis, a fifth detection axis, and a sixth detection axis and outputting a second signal; and a second correction unit that corrects the predetermined characteristics of the second signal based on second correction information to generate a second correction signal; A synthesis processing unit that generates a composite signal by combining a first detection signal based on the first correction signal and a second detection signal based on the second correction signal, A correction processing unit that corrects the predetermined characteristics of the composite signal based on the third correction information, It holds.

[0079] This sensor module generates a composite signal by combining a first detection signal based on a first correction signal and a second detection signal based on a second correction signal, thereby reducing random noise in the composite signal. Furthermore, even if the correction of predetermined characteristics of the first signal output from the first inertial sensor is insufficient and the deviation of the first correction signal is relatively large, or if the correction of predetermined characteristics of the second signal output from the second inertial sensor is insufficient and the deviation of the second correction signal is relatively large, the predetermined characteristics of the composite signal are further corrected, thereby suppressing a decrease in detection accuracy.

[0080] One embodiment of the sensor module is: The system may further include an alignment processing unit that generates the first detection signal by aligning the first detection axis, the second detection axis, and the third detection axis with mutually orthogonal first reference axis, second reference axis, and third reference axis for the first correction signal, and generates the second detection signal by aligning the fourth detection axis, the fifth detection axis, and the sixth detection axis with the first reference axis, second reference axis, and third reference axis for the second correction signal.

[0081] This sensor module corrects the misalignment between the first, second, and third detection axes of the first inertial sensor and the fourth, fifth, and sixth detection axes of the second inertial sensor, thereby suppressing a decrease in detection accuracy.

[0082] In one embodiment of the sensor module, The aforementioned predetermined characteristics may be temperature characteristics, linearity, or sensitivity characteristics.

[0083] This sensor module can improve temperature characteristics, linearity, or sensitivity characteristics.

[0084] In one embodiment of the sensor module, The order of correction of the correction processing unit may be greater than the order of correction of the first correction unit and the order of correction of the second correction unit.

[0085] This sensor module allows for precise correction of predetermined characteristics of the synthesized signal, thereby improving detection accuracy.

[0086] In one embodiment of the sensor module, The data acquisition conditions used to create the third correction information may differ from the data acquisition conditions used to create the first correction information and the data acquisition conditions used to create the second correction information.

[0087] This sensor module makes it easier to correct singularities that degrade certain characteristics of the composite signal, thereby further suppressing the decrease in detection accuracy.

[0088] In one embodiment of the sensor module, The number of data used to create the third correction information may be greater than the number of data used to create the first correction information and the number of data used to create the second correction information.

[0089] This sensor module makes it easier to correct singularities that degrade certain characteristics of the composite signal, thereby further suppressing the decrease in detection accuracy.

[0090] In one embodiment of the sensor module, At least one direction of the fourth detection axis, the fifth detection axis, and the sixth detection axis may be different from any of the directions of the first detection axis, the second detection axis, and the third detection axis.

[0091] This sensor module makes it easier for the singularity that degrades a predetermined characteristic of the first inertial sensor and the singularity that degrades a predetermined characteristic of the second inertial sensor to be different, thereby reducing the deviation of the predetermined characteristic of the combined signal and improving detection accuracy. [Explanation of Symbols]

[0092] 1...Sensor module, 2, 2A, 2B, 2C...Inertial Measurement Unit (IMU), 3...Memory unit, 4...Matching information, 5...Correction information, 9...Container, 10...Substrate, 20...Inertial sensor, 21...Outer case, 22...Inner case, 23...Bonding member, 24...Circuit board, 25...Joule connector, 26a, 26b, 26c...Angular velocity sensor, 27, 27A, 27B, 27C...Accelerometer, 28...Correction Circuit, 30...Memory unit, 31...Communication interface circuit, 90...Communication interface circuit, 91...Base, 92...Lid, 93...Connector, 100...Processing circuit, 101...Matching processing unit, 102...Synthesis processing unit, 103...Correction processing unit, 104...Calculation processing unit, 110...Internal connector, 211,212...Screw holes, 221...Opening, 241...Bottom surface of circuit board, 301...Correction information, 911...Recess, 931...Communication base

Claims

1. A first sensor device comprising: a first inertial sensor having a first detection axis, a second detection axis, and a third detection axis and outputting a first signal; and a first correction unit that corrects predetermined characteristics of the first signal based on first correction information and generates a first correction signal; A second sensor device comprising: a second inertial sensor having a fourth detection axis, a fifth detection axis, and a sixth detection axis and outputting a second signal; and a second correction unit that corrects the predetermined characteristics of the second signal based on second correction information and generates a second correction signal; A synthesis processing unit that generates a composite signal by combining a first detection signal based on the first correction signal and a second detection signal based on the second correction signal, A correction processing unit that corrects the predetermined characteristics of the composite signal based on the third correction information, A sensor module having the following features.

2. In claim 1, A sensor module further comprising an alignment processing unit that generates the first detection signal by aligning the first detection axis, the second detection axis, and the third detection axis with mutually orthogonal first reference axis, second reference axis, and third reference axis with respect to the first correction signal, and generates the second detection signal by aligning the fourth detection axis, the fifth detection axis, and the sixth detection axis with the first reference axis, second reference axis, and third reference axis with respect to the second correction signal.

3. In claim 1, The sensor module wherein the predetermined characteristics are temperature characteristics, linearity, or sensitivity characteristics.

4. In claim 1, A sensor module in which the order of correction of the correction processing unit is greater than the order of correction of the first correction unit and the order of correction of the second correction unit.

5. In claim 1, A sensor module in which the data acquisition conditions used to create the third correction information are different from the data acquisition conditions used to create the first correction information and the data acquisition conditions used to create the second correction information.

6. In claim 1, A sensor module in which the number of data used to create the third correction information is greater than the number of data used to create the first correction information and the number of data used to create the second correction information.

7. In claim 1, A sensor module in which at least one direction of the fourth detection axis, the fifth detection axis, and the sixth detection axis is different from any of the directions of the first detection axis, the second detection axis, and the third detection axis.

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