Inertial Sensor Device

Abstract

To provide an inertial sensor device that can appropriately combine pieces of detection data from a plurality of inertial sensors and has high detection accuracy.SOLUTION: An inertial sensor device has a plurality of inertial measurement modules including a first inertial measurement module, and the inertial sensor device comprises: a timing unit; a storage unit that stores pieces of detection data from the plurality of inertial measurement modules in association with the time of the timing unit; and a composition processing unit that calculates interpolation data at a predetermined time from the pieces of detection data at least at two points of time from the first inertial measurement module, and combines the pieces of detection data to generate output data at the predetermined time by using the interpolation data in each of the plurality of inertial measurement modules including the interpolation data.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to an inertial sensor device. [Background technology]

[0002] Inertial sensor devices equipped with an inertial sensor module having multiple inertial sensors, such as acceleration sensors and angular velocity sensors, are known. Inertial sensor devices are incorporated into various electronic devices and machines, or mounted on moving objects such as automobiles, and are used to monitor inertial quantities such as angular velocity and acceleration. They are also used in monitoring systems for structures such as bridges and elevated railways.

[0003] For example, Patent Document 1 proposes a technique in which a plurality of sensors, such as an IMU (Inertial Measurement Unit), are provided and the observed values ​​of the plurality of sensors are combined to improve detection accuracy. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 045099 Summary of the Invention [Problem to be solved by the invention]

[0005] However, Patent Document 1 has a problem in that if there is a difference in the detection timing between multiple sensors, the S / N ratio deteriorates, which may lead to a decrease in detection accuracy. This is a finding based on the verification results of the inventors, and is particularly noticeable when the detection data from the sensors is a digital signal, because it is discretized on the time axis. In other words, there has been a demand for an inertial sensor device that can appropriately combine detection data from multiple sensors and has high detection accuracy. [Means for solving the problem]

[0006] An inertial sensor device according to one aspect of the present application is an inertial sensor device having a plurality of inertial measurement modules including a first inertial measurement module, and comprises a timing unit, a memory unit that stores detection data from each of the plurality of inertial measurement modules in association with the time of the timing unit, and a synthesis processing unit that calculates interpolated data at a predetermined time using the detection data from the first inertial measurement module at at least two times, and synthesizes output data at the predetermined time using the interpolated data for each of the plurality of inertial measurement modules including the interpolated data. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view of an inertial sensor device according to a first embodiment. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] Rear view of the circuit board. [Figure 7] Circuit block diagram of the sensor module. [Figure 8] FIG. 4 is a timing chart showing the relationship between detected data and output data. [Figure 9] FIG. 10 is a waveform diagram showing errors due to jitter in detected data. [Figure 10] FIG. 2 is a circuit block diagram of a processing circuit in the inertial sensor device. [Figure 11] 10A and 10B are perspective views showing different aspects of the inertial sensor device. [Figure 12] 10A and 10B are perspective views showing different aspects of the inertial sensor device. [Figure 13] 10A and 10B are perspective views showing different aspects of the inertial sensor device. DETAILED DESCRIPTION OF THE INVENTION

[0008] Embodiment 1 ***Inertial Sensor Device Overview*** Fig. 1 is a perspective view showing an outline of an inertial sensor device, Fig. 2 is a transparent plan view of the inertial sensor device, and Fig. 3 is an exploded perspective view of the internal configuration of the inertial sensor device. Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments exemplify devices and methods for embodying the technical idea of ​​the present invention. The technical idea of ​​the present invention does not specify the materials, shapes, structures, arrangements, etc. of the components as described below. In the drawings, identical or similar elements are denoted by identical or similar reference numerals, and redundant explanations are omitted. The drawings are schematic and may include cases where the actual dimensions, relative proportions of dimensions, arrangements, structures, etc. differ from those shown.

[0009] As shown in FIGS. 1 to 3 , an inertial sensor device 1 according to an embodiment includes, for example, a substrate 10, a first sensor module 2A, a second sensor module 2B, and a third sensor module 2C mounted on the substrate 10, a processing circuit 100, and a container 9. The inertial sensor device 1 is a composite sensor module including multiple inertial sensors that detect acceleration in three axial directions and angular velocity around three axes. The inertial sensor device 1 detects the motion state of various objects, such as moving objects such as vehicles, robots, and drones, electronic devices such as smartphones and tablet devices, and other devices. The motion state includes, for example, position, attitude, velocity, acceleration, angular velocity, and the like.

[0010] 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 cover 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 first sensor module 2A, the second sensor module 2B, the third sensor module 2C, and the processing circuit 100. The container 9 protects the components accommodated in the accommodation space S from dust, moisture, ultraviolet rays, impact, and the like.

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

[0012] The inertial sensor device 1 includes a connector 93 attached to the side wall of the base 91, and a communication board 931 disposed in the accommodation space S. The connector 93 is a receptacle that provides electrical connection between the inside and outside of the container 9. The communication board 931 has a circuit that processes communication between the inertial sensor device 1 and an external device.

[0013] The substrate 10 is a circuit board including various elements and wiring. The substrate 10 is equipped with a first sensor module 2A, a second sensor module 2B, a third sensor module 2C, a processing circuit 100, an internal connector 110, and the like. The substrate 10 is fixed relatively to the base 91, for example.

[0014] 2 and 3, the first sensor module 2A and the second sensor module 2B are arranged along the X-axis on the underside of the substrate 10. The third sensor module 2C is arranged on the upper surface of the substrate 10 so as to overlap the first sensor module 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 second sensor module 2B when viewed from the direction along the Z-axis. In this way, by efficiently arranging various components with respect to the area of ​​the substrate 10 and the accommodation space S, the inertial sensor device 1 can be made smaller.

[0015] The first sensor module 2A, the second sensor module 2B, and the third sensor module 2C are connected to a processing circuit 100 via a substrate 10. The processing circuit 100 controls the driving of the first sensor module 2A, the second sensor module 2B, and the third sensor module 2C. The processing circuit 100 is connected to a communication substrate 931 via an internal connector 110 and wiring (not shown) connected to the internal connector 110.

[0016] The first sensor module 2A, the second sensor module 2B, and the third sensor module 2C have, for example, the same structure as one another. Hereinafter, any of the first sensor module 2A, the second sensor module 2B, and the third sensor module 2C will be simply referred to as the "sensor module 2," and redundant explanations will be omitted. The sensor module will also be referred to as the inertial measurement module. The number of sensor modules 2 is not limited to three, and may be two, four, or more.

[0017] ***Sensor module configuration*** Figure 4 is an exploded perspective view of the sensor module, Figure 5 is a front view of the circuit board, and Figure 6 is a rear view of the circuit board. As shown in FIG. 4, the sensor module 2 includes an outer case 21, an inner case 22, a joint 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 joint member 23 while accommodating and holding the circuit board 24. The sensor module 2 has a square shape when viewed from above, that is, from a direction along the c-axis shown in FIG. 4. The outer case 21 has, for example, screw holes 211 and 212 provided at each of a pair of diagonally opposite corners on the top surface. The sensor module 2 can be fixed to the substrate 10 by using screws to fasten the screw holes 211 and 212.

[0018] As shown in FIGS. 5 and 6 , the circuit board 24 is mounted with a module connector 25, a first angular velocity sensor 26a, a second angular velocity sensor 26b, a third angular velocity sensor 26c, an acceleration sensor 27, a signal processing unit 28, and the like. The module connector 25 connects the sensor module 2 and the substrate 10. The module connector 25 is exposed to the substrate 10, for example, through an opening 221 provided in the inner case 22. The first angular velocity sensor 26a detects an angular velocity ωa around the a-axis. The second angular velocity sensor 26b detects an angular velocity ωb around the b-axis. The third angular velocity sensor 26c detects an angular velocity ωc around the c-axis. The acceleration sensor 27 detects an acceleration Aa along the a-axis, an acceleration Ab along the b-axis, and an acceleration Ac along the c-axis. The three detection axes, a, b, and c, are defined for each sensor module 2.

[0019] The signal processing unit 28 is configured by, for example, an integrated circuit (IC). The signal processing unit 28 is connected to the first angular velocity sensor 26a, the second angular velocity sensor 26b, the third angular velocity sensor 26c, and the acceleration sensor 27 via the circuit board 24. The signal processing unit 28 is connected to the processing circuit 100 via the circuit board 24, the module connector 25, the board 10, etc.

[0020] The circuit board 24 has, for example, a square shape when viewed in the direction along the c-axis. When four quadrants defined around the center O of the circuit board 24 are a first quadrant Q1, a second quadrant Q2, a third quadrant Q3, and a fourth quadrant Q4, the acceleration sensor 27 is disposed in the first quadrant Q1. As shown in FIG. 3 , the first sensor module 2A, the second sensor module 2B, and the third sensor module 2C are disposed such that their first quadrants Q1 are adjacent to each other.

[0021] 3, the acceleration sensor 27A of the first sensor module 2A and the acceleration sensor 27C of the third sensor module 2C are arranged to overlap each other when viewed along the Z axis. The acceleration sensor 27A of the first sensor module 2A and the acceleration sensor 27B of the second sensor module 2B are arranged to overlap each other when viewed along the X axis. This makes it possible to minimize the difference in acceleration experienced by the acceleration sensors 27A, 27B, and 27C.

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

[0023] ***Sensor module configuration*** FIG. 7 is a block diagram showing the circuit configuration of the sensor module. 7, the sensor module 2 includes an inertial sensor 20 including at least one of a first angular velocity sensor 26a, a second angular velocity sensor 26b, a third angular velocity sensor 26c, and an acceleration sensor 27, a signal processing unit 28, a timing unit 32, a communication unit 31, and a storage unit 30. The communication unit 31 includes the module connector 25 (FIG. 5). The storage unit 30 stores, for example, various parameters used for correction in the signal processing unit 28.

[0024] The inertial sensor 20 outputs signals relating to multiple detection axes to the signal processing unit 28. The signal processing unit 28 corrects the signals output from the inertial sensor 20 so that the multiple detection axes are orthogonal to one another. For example, multiple detection axes forming a three-dimensional orthogonal coordinate system are set for each sensor module 2. In addition, the signal processing unit 28 corrects offset errors and scale factor errors contained in the signals input from the inertial sensor 20. The corrected inertial data is then read out by the processing circuit 100 (FIG. 10) of the inertial sensor device 1 at a timing synchronized with an output synchronization signal, which will be described later.

[0025] The clock unit 32 is a timer circuit equipped with an oscillator such as a quartz oscillator, and supplies a clock signal to the signal processing unit 28 . The communication unit 31 is a digital interface circuit, and enables two-way communication with the processing circuit 100 (FIG. 3) of the inertial sensor device 1 via the module connector 25 (FIG. 5).

[0026] ***Issues with conventional technology*** FIG. 8 is a timing chart showing the relationship between the detected data and the output data. The top of FIG. 8 shows the timing of reading out the inertial data in the first sensor module 2A. First, the first sensor module 2A acquires inertial data at the timing of the clock in its own timer 32. The sampling period is, for example, 2 kHz, but is not limited to this and may be, for example, 20 kHz. Next, when acquisition of inertial data for one sampling is completed, an output synchronization signal (Data Ready) is output. The Data Ready signal is synchronized with the sampling period. Here, since each sensor module 2 has its own timer 32, the output synchronization signal is transmitted based on the clock of each sensor module 2. More specifically, the first sensor module 2A outputs the output synchronization signal in accordance with the timing of the clock in its own timer 32. The same is true for the second sensor module 2B and the third sensor module 2C.

[0027] When the processing circuit 100 of the inertial sensor device 1 receives the output synchronization signal, it reads inertial data from the first sensor module 2A in synchronization with the output synchronization signal and stores the data as detection data Da[1] in the first storage unit 41 (FIG. 10). At this time, the detection data Da[1] is stored as a pair with the read time Ta[1] of the data. The time Ta[1] is the read time of the detection data Da[1] based on the clock of the timer unit 40 (FIG. 10) of the processing circuit 100.

[0028] Similarly, the second sensor module 2B outputs an output synchronization signal (Data Ready) at the timing of the clock in its own timer 32. Then, in synchronization with the output synchronization signal, the inertial data is read out, and the detection data Db[1] and the time Tb[1] are stored as a pair. Similarly, the third sensor module 2C outputs an output synchronization signal (Data Ready) at the timing of the clock in its own timer 32. Then, in synchronization with the output synchronization signal, the inertial data is read out, and the detection data Dc[1] and the time Tc[1] are stored as a pair.

[0029] 8, there is a slight difference between the read time Ta[1] of the detection data Da[1] of the first sensor module 2A and the read time Tb[1] of the detection data Db[1] of the second sensor module 2B. In other words, there is a time axis difference between the read time Ta[1] and the read time Tb[1]. Similarly, there is jitter between the read time Ta[1] and the read time Tc[1], and between the read time Tb[1] and the read time Tc[1]. This is because each sensor module 2 has its own timer 32 and outputs an output synchronization signal based on that time. If the output data at Ts[1] is simply generated from Da[1], Db[1], and Dc[1], the data used will be shifted on the time axis from time Ts[1], in other words, data with jitter error, which will result in an error in the output data.

[0030] As an example, consider the difference between the detection data Da[1] of the first sensor module 2A and the detection data Db[1] of the second sensor module 2B, that is, the jitter error. 9 is a waveform diagram showing detected data 70 from the first sensor module 2A and detected data 71 from the second sensor module 2B, as well as the difference therebetween (error waveform 72 of jitter error) when the same 100 Hz sine wave is input to the first sensor module 2A and the second sensor module 2B when there is a frequency difference between the clocks of the first sensor module 2A and the second sensor module 2B. The vertical axis represents time (sec), and the vertical axis represents signal level. The waveform diagram in FIG. 9 is based on the results of a simulation, which was performed using a program on a PC (Personal Computer).

[0031] The error waveform 72 exhibits a beat waveform that gradually increases while oscillating over time, then returns to zero, and then increases while oscillating over time again, reaching a maximum value of approximately 25%. If there is a frequency difference between the clock of the second sensor module 2B and the clock of the third sensor module 2C, a jitter error will also occur between the detection data of the second sensor module 2B and the detection data of the third sensor module 2C when the same 100 Hz sine wave is input to the second sensor module 2B and the third sensor module 2C. Therefore, it is clear that simply combining the detection data Da[1] of the first sensor module 2A, the detection data Db[1] of the second sensor module 2B, and the detection data Dc[1] of the third sensor module 2C will result in an error.

[0032] ***Circuit block configuration of the processing circuit in the inertial sensor device*** FIG. 10 is a circuit block diagram of a processing circuit in the inertial sensor device. As shown in FIG. 10, the processing circuit 100 of the inertial sensor device 1 includes a clock unit 40, a first storage unit 41, a second storage unit 42, a synthesis processing unit 43, a communication unit 44, and the like.

[0033] The timekeeping unit 40 is a timer circuit equipped with an oscillator such as a quartz oscillator, and supplies a clock signal and time data to the synthesis processing unit 43, the first storage unit 41, and the like. The first storage unit 41 is a buffer memory including a RAM (Random Access Memory) and has three storage areas 41a, 41b, and 41c, one for each sensor module 2. The storage area 41a stores the detection data Da[n] and the read time Ta[n] of the first sensor module 2A, and stores the data as a linked detection data pair (Ta[1], Da[1]). The storage area 41a also has a storage area capable of storing multiple sets of detection data pairs in chronological order. For example, the storage area 41a is configured to store five sets of detection data pairs. The number of sets is not limited to five, but may be any number required for the interpolation process described below. The same applies to the storage areas 41b and 41c. In other words, the first storage unit 41 stores the detection data of each of the multiple sensor modules 2 in association with the time of the timer 40.

[0034] The second storage unit 42 is a main memory configured to include a ROM (Read Only Memory) and a RAM, and stores programs executed by the synthesis processing unit 43, related data, etc. The programs include an interpolation processing program, which will be described later. Note that the first storage unit 41 may be provided as a part of the second storage unit 42. The synthesis processing unit 43 is a control unit of the processing circuit 100 and is configured to include one or more processors. The synthesis processing unit 43 performs interpolation processing on the detection data from each sensor module 2 to achieve synchronization, and synthesizes the interpolated detection data to generate output data. Details of the interpolation processing will be described later. The communication unit 44 is an interface circuit, and outputs the output data from the synthesis processing unit 43 to an external device from the connector 93 via the internal connector 110 (FIG. 2) and the communication board 931.

[0035] ***Detection data interpolation process-1 (past linear interpolation)*** Here, the interpolation process of the detection data by the synthesis processing unit 43 and the method of generating output data will be described with reference to Fig. 8 and Fig. 10. Note that Main sync in Fig. 8 indicates the reference signal Ts[n] at the reference clock (2 kHz) in the timing unit 40 of the processing circuit 100.

[0036] In this embodiment, the synthesis processing unit 43 uses the two most recent pairs of detection data that are older than the timing of the reference signal Ts[3] to linearly interpolate interpolated data for the timing of the previous reference signal Ts[2] for the detection data from each sensor module 2. The timing of the reference signal Ts[3] corresponds to a predetermined time. Specifically, for the detection data pair (Ta[n], Da[n]) of the first sensor module 2A, linear interpolation is performed using equation (1) to obtain interpolated data DaTs[2] at the timing of the reference signal Ts[2]. Similarly, the second sensor module 2B obtains interpolated data DbTs[2] using equation (2), and the third sensor module 2C obtains interpolated data DcTs[2] using equation (3).

[0037] DaTs[2]=Da[2]+{(Da[3]-Da[2]) / (Ta[3]-Ta[2])}*(Ts[2]-Ta[2]) ...Equation (1) DbTs[2]=Db[2]+{(Db[3]-Db[2]) / (Tb[3]-Tb[2])}*(Ts[2]-Tb[2]) ...Equation (2) DcTs[2]=Dc[2]+{(Dc[3]-Dc[2]) / (Tc[3]-Tc[2])}*(Ts[2]-Tc[2]) ...Equation (3)

[0038] In formula (1), the amount of change is obtained from the difference between the detected data Da[3] and the previous detected data Da[2], and the slope is calculated by dividing the amount of change by the difference between the read time Ta[3] and the read time Ta[2]. The amount of error change on the time axis is calculated by multiplying the slope by the difference between the time of the reference signal Ts[2] and the read time Ta[2]. Then, Da[2], the base value of the detected data, is added. As a result, interpolated data DaTs[2] at the timing of reference signal Ts[2] is derived. The same applies to formulas (2) and (3). In other words, the synthesis processing unit 43 calculates interpolated data by interpolating the detection data at two times using linear function formulas (1) to (3). Furthermore, the timing of reference signal Ts[3] as a predetermined time is later than the two times, readout time Ta[2] and readout time Ta[3].

[0039] Next, a method for synthesizing the interpolated data DaTs[2], DbTs[2], and DcTs[2] obtained from equations (1) to (3) will be described. The synthesis processing unit 43 synthesizes the three pieces of interpolated data using the formula (4) to generate the output data DsTs[3].

[0040] DsTs[3]=(DaTs[2]+DbTs[2]+DcTs[2]) / 3...Equation (4)

[0041] As shown in formula (4), the synthesis processing unit 43 averages the interpolated data DaTs[2], the interpolated data DbTs[2], and the interpolated data DcTs[2] to generate the output data DsTs[3]. In other words, the synthesis processing unit 43 calculates interpolated data at a predetermined time from the detection data of the first sensor module 2A at at least two times, and synthesizes the output data at the predetermined time using the interpolated data for each of the multiple sensor modules 2A, including the interpolated data.

[0042] As described above, the inertial sensor device 1 of this embodiment can provide the following effects. The inertial sensor device 1 is an inertial sensor device having a plurality of sensor modules including a first sensor module 2A as a first inertial measurement module, and is equipped with a timing unit 40, a first memory unit 41 as a memory unit that stores the detection data of each of the plurality of sensor modules 2 in association with the time of the timing unit 40, and a synthesis processing unit 43 that calculates interpolated data at a predetermined time using the detection data of the first sensor module 2A at at least two times, and synthesizes output data at the predetermined time using the interpolated data for each of the plurality of sensor modules 2 including the interpolated data.

[0043] According to this method, interpolated data synchronized at a predetermined time is calculated for each inertial measurement module. Then, the synthesis processing unit 43 averages and synthesizes the multiple interpolated data with the time axes aligned to generate output data. Therefore, by performing interpolation processing on multiple detection data that were previously discrete due to digital output, the time axes can be aligned, thereby reducing jitter noise that changes over time. Furthermore, when N pieces of detection data are synthesized, random noise can be reduced to 1 / √N, thereby improving detection accuracy. Therefore, it is possible to provide an inertial sensor device 1 that can appropriately combine detection data from a plurality of inertial measurement modules and has high detection accuracy.

[0044] Furthermore, the synthesis processing unit 43 calculates interpolated data by interpolating the detection data at two times using equations (1) to (3), which are linear functions. This allows the interpolation data to be calculated using a simple linear function, thereby reducing the storage capacity of the second storage unit 42 related to the interpolation process and reducing the load of the calculation process in the synthesis processing unit 43.

[0045] Furthermore, the timing of the reference signal Ts[3] as the predetermined time is later than the read time Ta[2] and the read time Ta[3] as the two times. This allows interpolated data to be obtained by linear interpolation using two pairs of detected data from a time before a predetermined time.

[0046] Embodiment 2 ***Detection data interpolation process-2 (past secondary interpolation)*** In the above embodiment, the interpolated data is calculated by linearly interpolating the detection data at two times using a linear function, but the present invention is not limited to this method, and it is sufficient that the interpolated data is calculated by interpolating the detection data at n+1 or more times using an n-th order function. Hereinafter, the same parts as in the above embodiment will be assigned the same numbers, and duplicated explanations will be omitted.

[0047] In this embodiment, the synthesis processing unit 43 uses the three most recent pairs of detection data prior to the timing of the reference signal Ts[3] to obtain interpolated data for the detection data from each sensor module 2 at the timing of the previous reference signal Ts[2] by quadratic interpolation. First, the basic equation for quadratic interpolation is Equation (5).

[0048] Dn[y]=a1*(Tn[x]) 2 +b1*(Tn[x])+c1 …Equation (5)

[0049] Specifically, in the first sensor module 2A, the three most recent detection data pairs (Ta[1], Da[1]), (Ta[2], Da[2]), and (Ta[3], Da[3]) are substituted into equation (5) to obtain equations (6) to (8).

[0050] Da[1]=a1*(Ta[1])*(Ta[1])+b1*(Ta[1])+c1...Formula (6) Da[2]=a1*(Ta[2])*(Ta[2])+b1*(Ta[2])+c1...Equation (7) Da[3]=a1*(Ta[3])*(Ta[3])+b1*(Ta[3])+c1...Equation (8) Then, the simultaneous equations of formulas (6) to (8) are solved to find the coefficients a1, b1, and c1.

[0051] Similarly, for the second sensor module 2B and the third sensor module 2C, the three most recent pairs of detection data from the past are substituted into equation (5) to obtain equations (9) to (11) and equations (12) to (14).

[0052] Db[1]=a2*(Tb[1])*(Tb[1])+b2*(Tb[1])+c2...Formula (9) Db[2]=a2*(Tb[2])*(Tb[2])+b2*(Tb[2])+c2...Formula (10) Db[3]=a2*(Tb[3])*(Tb[3])+b2*(Tb[3])+c2...Formula (11) Then, the simultaneous equations of formulas (9) to (11) are solved to find the coefficients a2, b2, and c2.

[0053] Dc[1]=a3*(Tc[1])*(Tc[1])+b3*(Tc[1])+c3...Formula (12) Dc[2]=a3*(Tc[2])*(Tc[2])+b3*(Tc[2])+c3...Formula (13) Dc[3]=a3*(Tc[3])*(Tc[3])+b3*(Tc[3])+c3...Formula (14) Then, the simultaneous equations of formulas (12) to (14) are solved to find the coefficients a3, b3, and c3.

[0054] Next, the interpolated data DaTs[2], DbTs[2], and DcTs[2] at the timing of the reference signal Ts[2] are calculated by quadratic interpolation using formulas 15 and 16. In other words, the synthesis processing unit 43 calculates the interpolated data by interpolating the detection data at the three times using a quadratic function.

[0055] DaTs[2]=a1*Ts[2] 2 +b1*Ts[2]+c1 …Equation (15) DbTs[2]=a2*Ts[2] 2 +b2*Ts[2]+c2 …Equation (16) DcTs[2]=a3*Ts[2] 2 +b3*Ts[2]+c3 ...Equation (17)

[0056] Next, a method for synthesizing the interpolated data DaTs[2], DbTs[2], and DcTs[2] obtained from equations (15) to (17) will be described. The synthesis processing unit 43 synthesizes the three interpolated data using the formula (18) to generate output data.

[0057] DsTs[3]=(DaTs[2]+DbTs[2]+DcTs[2]) / 3...Equation (18)

[0058] As shown in equation (18), the synthesis processing unit 43 averages the interpolated data DaTs[2], the interpolated data DbTs[2], and the interpolated data DcTs[2] to generate the output data DsTs[3].

[0059] As described above, according to the inertial sensor device 1 of this embodiment, in addition to the effects of the above embodiment, the following effects can be obtained. The synthesis processing unit 43 calculates interpolated data by interpolating the detection data at three times using a quadratic function. Specifically, the synthesis processing unit 43 substitutes the three most recent pairs of detection data from the past into equation (5) to set up three simultaneous equations, solves the simultaneous equations to find coefficients, and then calculates interpolated data at the timing of the reference signal immediately before the specified time. According to this, since the interpolated data is calculated by quadratic interpolation using a quadratic function, the interpolation accuracy can be further improved, and jitter noise can be further reduced. Therefore, it is possible to provide an inertial sensor device 1 that can appropriately combine detection data from a plurality of inertial measurement modules and has high detection accuracy.

[0060] Furthermore, the synthesis processing unit 43 calculates interpolated data by interpolating the detected data at n+1 or more times using an n-th order function. According to this, since the interpolated data is calculated by n-th order interpolation using an n-th order function, the interpolation accuracy can be further improved, and jitter noise can be further reduced.

[0061] Embodiment 3 ***Detection data interpolation processing-3 (future linear interpolation)*** In the first embodiment, the interpolation data at the timing of the reference signal Ts[2] immediately before the predetermined time is calculated by linear interpolation, but the interpolation data at the timing of the predetermined time may be calculated. Hereinafter, the same parts as those in the above embodiment are assigned the same numbers, and redundant explanations will be omitted.

[0062] In this embodiment, the synthesis processing unit 43 uses the two most recent pieces of data at the timing Ts[3] as a predetermined time to obtain interpolated data at the timing Ts[3] by linear interpolation. Specifically, for the detection data pair (Ta[n], Da[n]) of the first sensor module 2A, linear interpolation is performed using equation (19) to obtain interpolated data DaTs[3] at the timing of the reference signal Ts[3]. Similarly, the second sensor module 2B obtains interpolated data DbTs[3] using equation (20), and the third sensor module 2C obtains interpolated data DcTs[3] using equation (21).

[0063] DaTs[3]=Da[3]+{(Da[3]-Da[2]) / (Ta[3]-Ta[2])}*(Ts[3]-Ta[3]) ...Equation (19) DbTs[3]=Db[3]+{(Db[3]-Db[2]) / (Tb[3]-Tb[2])}*(Ts[3]-Tb[3]) ...Equation (20) DcTs[3]=Dc[3]+{(Dc[3]-Dc[2]) / (Tc[3]-Tc[2])}*(Ts[3]-Tc[3]) ...Equation (21)

[0064] In equation (19), the amount of change is obtained from the difference between the detected data Da[3] and the previous detected data Da[2], and the amount of change is divided by the difference between the read time Ta[3] and the read time Ta[2] to calculate the slope. The amount of error change on the time axis is derived by multiplying the slope by the difference between the time of the reference signal Ts[3] and the read time Ta[3]. Then, Da[3], which is the base value of the detected data, is added. As a result, the interpolated data DaTs[3] at the timing of the reference signal Ts[3] is derived. The same applies to formulas (20) and (21).

[0065] The three pieces of interpolated data obtained from equations (19) to (21) are synthesized using equation (22). More specifically, the synthesis processing unit 43 averages the three pieces of interpolated data to generate output data DsTs[3].

[0066] DsTs[3]=(DaTs[3]+DbTs[3]+DcTs[3]) / 3...Equation (22)

[0067] As described above, according to the inertial sensor device 1 of this embodiment, in addition to the effects of the first embodiment, the following effects can be obtained. The synthesis processing unit 43 uses the two most recent pieces of data at the timing Ts[3] as a predetermined time to obtain interpolated data at the timing Ts[3] by linear interpolation. This allows interpolation data at the predetermined time Ts[3] to be derived without delay, thereby reducing jitter noise without delay.

[0068] Embodiment 4 ***Detection data interpolation processing-4 (future quadratic interpolation)*** In the second embodiment, the interpolation data at the timing of the reference signal Ts[2] immediately before the predetermined time is calculated by secondary interpolation, but the interpolation data at the timing of the predetermined time may be calculated. Hereinafter, the same parts as those in the above embodiment are assigned the same numbers, and redundant explanations will be omitted.

[0069] In this embodiment, the synthesis processing unit 43 uses the latest three pairs of detection data that are older than the timing of the reference signal Ts[3] to obtain interpolated data at the timing of the reference signal Ts[3], which is a predetermined time, by quadratic interpolation. Note that the basic equation for quadratic interpolation is the above-mentioned equation (5).

[0070] First, the processing of equations (6) to (14) is the same as that described in embodiment 2. In more detail, for each sensor module 2, the three most recent pairs of detection data from the past are substituted into equation (5) to formulate three simultaneous equations, and the simultaneous equations are solved to find three coefficients for each sensor module 2.

[0071] This embodiment differs from the second embodiment in that the interpolated data DaTs[3], DbTs[3], and DcTs[3] at the timing of the reference signal Ts[3] are calculated by quadratic interpolation using equations (23) to (25).

[0072] DaTs[3]=a1*Ts[3] 2 +b1*Ts[3]+c1…Formula (23) DbTs[3]=a2*Ts[3] 2 +b2*Ts[3]+c2 …Equation (24) DcTs[3]=a3*Ts[3] 2 +b3*Ts[3]+c3 ...Equation (25)

[0073] Next, the interpolated data DaTs[3], DbTs[3], and DcTs[3] obtained from equations (23) to (25) are synthesized using equation (26) to generate output data DsTs[3].

[0074] DsTs[3]=(DaTs[3]+DbTs[3]+DcTs[3]) / 3...Equation (26)

[0075] As shown in equation (26), the synthesis processing unit 43 averages the interpolated data DaTs[3], the interpolated data DbTs[3], and the interpolated data DcTs[3] to generate the output data DsTs[3].

[0076] As described above, the inertial sensor device 1 of this embodiment can provide the following effects in addition to the effects of the second embodiment. The synthesis processing unit 43 uses the latest three pieces of data at the timing Ts[3] as a predetermined time to obtain interpolated data at the timing Ts[3] by secondary interpolation. This allows interpolation data at the predetermined time Ts[3] to be derived without delay, thereby reducing jitter noise without delay.

[0077] Embodiment 5 ***Different aspects of inertial sensor devices*** Fig. 11 is a perspective view showing a different embodiment of the inertial sensor device, and corresponds to Fig. 3. Fig. 12 is a perspective view showing a different embodiment of the inertial sensor device, and corresponds to Fig. 3. Fig. 13 is a perspective view showing a different embodiment of the inertial sensor device, and corresponds to Fig. 3.

[0078] The configuration of the inertial sensor device 1 is not limited to the configuration described in FIGS. 1 to 3, and may be a different configuration. For example, as shown in FIG. 11, the inertial sensor device 1A of this embodiment includes a first sensor module 2A, a second sensor module 2B, and a third sensor module 2C stacked in one direction, i.e., along the Z axis. The inertial sensor device 1A further includes four boards 10A, 10B, 10C, and 10D, and a processing circuit 100 and an internal connector 110 mounted on each board 10D. The boards 10A to 10D are fixed relative to each other. The first sensor module 2A is mounted on the board 10A. The second sensor module 2B is mounted on the board 10B. The third sensor module 2C is mounted on the board 10C.

[0079] The first sensor module 2A, the second sensor module 2B, and the third sensor module 2C are connected to the processing circuit 100 in a daisy chain by multiple cables 4a, 4b, and 4c. The cables 4a, 4b, and 4c connect the first sensor module 2A, the second sensor module 2B, the third sensor module 2C, and the processing circuit 100 via connectors mounted on the substrates 10A, 10B, and 10C, respectively. By connecting the sensor modules 2 in series, design flexibility is improved, and the number of sensor modules can be easily increased. This further improves the S / N ratio of the output signal.

[0080] 12, the inertial sensor device 1B of this embodiment includes a first sensor module 2A, a second sensor module 2B, and a third sensor module 2C arranged on the same plane. The inertial sensor device 1B includes substrates 10A to 10D arranged on a single plane along the XY plane. As in the example shown in FIG. 11, the first sensor module 2A, the second sensor module 2B, and the third sensor module 2C are connected to the processing circuit 100 in a daisy chain by multiple cables 4a, 4b, and 4c. This improves design flexibility and makes it easy to increase the number of sensor modules.

[0081] 13, the inertial sensor device 1C of this embodiment includes a single substrate 10E instead of the multiple substrates 10A to 10D arranged on the same plane. The first sensor module 2A, the second sensor module 2B, the third sensor module 2C, the processing circuit 100, and the internal connector 110 are mounted on the substrate 10E. The substrate 10E has wiring that connects the first sensor module 2A, the second sensor module 2B, and the third sensor module 2C to the processing circuit 100. The processing circuit 100 is connected in parallel to each sensor module 2, for example. This allows for more efficient use of communication capacity than with serial wiring.

[0082] These inertial sensor devices 1A, 1B, and 1C can also provide the same effects as those of the above-described embodiments. [Explanation of symbols]

[0083] REFERENCE SIGNS LIST 1...inertial sensor device, 1A to 1C...inertial sensor device, 2...sensor module, 2A...first sensor module, 2B...second sensor module, 2C...third sensor module, 4a to 4c...cable, 9...container, 10...board, 10A to 10E...board, 20...inertial sensor, 21...outer case, 22...inner case, 23...joint member, 24...circuit board, 25...module connector, 26a...first angular velocity sensor, 26b...second angular velocity sensor, 26c...third angular velocity sensor, 27...acceleration sensor , 27A to 27C...acceleration sensor, 28...signal processing unit, 30...memory unit, 31...communication unit, 32...timekeeping unit, 40...timekeeping unit, 41...first memory unit, 41a...memory area, 41b...memory area, 42...second memory unit, 43...synthesis processing unit, 44...communication unit, 70...reference data waveform, 71...detected data waveform, 72...error waveform, 91...base, 92...lid, 93...connector, 100...processing circuit, 110...internal connector, 211, 212...screw holes, 221...opening, 241...upper surface, 242...lower surface, 911...recess, 931...communication board.

Claims

1. An inertial sensor device having a plurality of inertial measurement modules including a first inertial measurement module. There was, A timing unit; Associating the detected data of each of the plurality of inertial measurement modules with the time of the clock unit a storage unit for storing the The detection data of the first inertial measurement module at at least two times and the Using both the two times, interpolated data at a predetermined time is calculated, and the interpolated data is included in the and synthesizing the interpolated data at the predetermined time for each of the plurality of inertial measurement modules. and a synthesis processing unit that generates output data at the predetermined time. Inertial sensor device.

2. The synthesis processing unit interpolates the detection data at n+1 or more times using an n-th order function. and calculating the interpolated data. The inertial sensor device according to claim 1 .

3. The synthesis processing unit interpolates the detection data at the two times using a linear function. and calculating the interpolated data. The inertial sensor device according to claim 1 .

4. The predetermined time is a time later than the two times. The inertial sensor device according to claim 3 .

5. The synthesis processing unit interpolates the detection data at three times using a quadratic function. The interpolated data is calculated by The inertial sensor device according to claim 1 .

6. An inertial sensor device having a plurality of inertial measurement modules including a first inertial measurement module. There was, A timing unit; Associating the detected data of each of the plurality of inertial measurement modules with the time of the clock unit a storage unit for storing the For each of the detection data of the plurality of inertial measurement modules, By using the detection data of at least two times of the rule and the at least two times , and performs interpolation processing to synchronize the predetermined values ​​for each of the interpolated inertial measurement modules. a synthesis process for synthesizing the detected data at a time and generating output data at the predetermined time; and a logic unit, Inertial sensor device.

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