Measurement data synchronization method, test method, and computer program

Abstract

To provide a measurement data synchronization method in which time-series data output from a plurality of measuring instruments can be accurately synchronized.SOLUTION: A measurement data synchronization method in which time-sequences output from first through fifth measuring instruments are synchronized by a data analysis device comprises: a step ST1 of acquiring first through fifth reference data output from the first through fifth measuring instruments when a reference signal including a stationary interval and a rising interval is simultaneously input into the first through fifth measuring instruments; steps ST3-ST5 of generating data after first through fifth filter processing by performing median filter processing in which median values within predetermined time width are extracted for first through fifth reference data; a step ST6 of calculating first through fifth rising times as rising timing information from each of pieces of data after the first through fifth filter processing; and a step ST7 of synchronizing first through fifth measurement data output from the first through fifth measuring instruments on the basis of the first through fifth rising times.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a measurement data synchronization method, a test method, and a computer program. More specifically, the present invention relates to a measurement data synchronization method, a test method, and a computer program for synchronizing time-series data output from a plurality of measuring instruments by a computer.

Background Art

[0002] In recent years, the development of electric vehicles that run using electric energy, such as secondary battery electric vehicles, fuel cell vehicles, hybrid vehicles, and plug-in hybrid vehicles, has been actively carried out. The energy flow in an electric vehicle changes rapidly during driving. Therefore, tests for evaluating the performance of electric vehicles require more measuring instruments and more complicated procedures compared to tests for internal combustion engine vehicles that run only on power generated by an internal combustion engine. For example, in the test of a hybrid vehicle, a plurality of measuring instruments for acquiring various data, such as vehicle environmental information, speed, travel distance, current, voltage, electric energy, and exhaust gas-related data (exhaust gas concentration, exhaust gas flow rate, etc.), are used in combination.

[0003] In the test of an electric vehicle, the timing of operating each measuring instrument varies depending on the content of the test. In addition, many commonly used measuring instruments do not have a function of operating in synchronization with other measuring instruments. Therefore, in order to analyze a plurality of measurement data obtained by each measuring instrument by a computer, it is necessary to perform preprocessing for synchronizing the plurality of measurement data in advance. Conventionally, such synchronization of measurement data has been performed manually by an operator, which takes time and may cause variations in test results.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] Incidentally, if we can extract the rising edge of a signal, as shown in Figure 8, from each measurement data, which is one-dimensional time-series data, it may be possible to synchronize each measurement data based on this rising edge.

[0006] Figure 8 shows an example of the output of a measuring instrument (see thin solid line) when a step-shaped reference signal (see thin dashed line) is input to the measuring instrument. Figure 8 also shows the measurement data obtained by applying the processing described in Patent Document 2 to the measurement data shown by the thin solid line, as shown by the thick dashed line.

[0007] As shown by the thin solid line in Figure 8, measurement data from measuring instruments generally contains harmonic noise and offsets, making it difficult to accurately extract the rising edge. Therefore, as shown in Patent Document 1, it is conceivable to remove harmonic noise and offsets from the measurement data by applying differential processing, integral processing, and harmonic removal processing using a low-pass filter to the measurement data. However, as shown by the thick dashed line in Figure 8, when a low-pass filter is applied to the measurement data to remove high-frequency components, the rising edge is delayed, making it impossible to accurately extract the rising edge, and consequently, it becomes impossible to accurately synchronize the measurement data.

[0008] The present invention aims to provide a measurement data synchronization method, a testing method, and a computer program that can accurately synchronize time-series data output from multiple measuring instruments. [Means for solving the problem]

[0009] (1) The measurement data synchronization method according to the present invention is a method for synchronizing time-series data output from a plurality of measuring instruments (for example, measuring instruments 31 to 35 described later) using a computer (for example, a data analysis device 5 described later), and is characterized by comprising the steps of: acquiring reference data, which is time-series data output from each measuring instrument, when a reference signal including a steady interval and a rising interval is simultaneously input to the plurality of measuring instruments; generating a plurality of filtered data by applying a median filter process to the plurality of reference data to extract the median value within a predetermined time width; acquiring rising timing information from each of the plurality of filtered data; and synchronizing the time-series data output from the plurality of measuring instruments based on the plurality of rising timing information.

[0010] (2) In this case, in the step of generating the filtered data, it is preferable to adjust the time width so that the signal values ​​included in the steady interval of the filtered data remain within a predetermined range over the evaluation time.

[0011] (3) In this case, in the step of acquiring the reference data, it is preferable to use a signal that changes in a ramp-like manner in the rising edge section as the reference signal, and in the step of generating the filtered data, it is preferable to perform differential processing on the reference data and then perform median filtering.

[0012] (4) In this case, in the step of acquiring the rise time information, it is preferable to acquire the time when the signal value exceeds a predetermined threshold in the filtered data as the rise time.

[0013] (5) In this case, in the step of acquiring the reference data, it is preferable to use a signal that changes in a ramp-like manner in the rising edge section as the reference signal, and in the step of acquiring the rising edge timing information, it is preferable to calculate the slope and intercept of a linear function generated based on a plurality of signal values ​​included in the rising edge section of the filtered data, and to calculate the delay time of the rising edge of the filtered data based on the slope and intercept.

[0014] (6) The present invention provides a test method for evaluating the performance of a test specimen by processing time-series data output from a plurality of measuring instruments (for example, measuring instruments 31 to 35 described later) using a computer (for example, a data analysis device 5 described later), comprising the steps of: acquiring reference data, which is time-series data output from each measuring instrument when a reference signal including a steady-state interval and a rising-point interval is simultaneously input to the reference signal channel of each of the plurality of measuring instruments; and acquiring measurement data, which is time-series data output from each measuring instrument when a signal correlated with the state of the test specimen is input to the measurement channel of each of the plurality of measuring instruments; generating a plurality of filtered data by applying a median filter to the plurality of reference data to extract the median value within a predetermined time width; acquiring rising-point timing information from each of the plurality of filtered data; synchronizing the plurality of measurement data based on the plurality of rising-point timing information; and evaluating the performance of the test specimen based on the synchronized plurality of measurement data. [Effects of the Invention]

[0015] (1) In the present invention, a reference signal including a steady-state interval and a rising-edge interval is input to multiple measuring instruments simultaneously, and reference data, which is time-series data output from each measuring instrument, is acquired. Multiple filtered data are generated by applying a median filter to the multiple reference data to extract the median value within a predetermined time width. Rising-edge timing information is acquired from each of these filtered data, and the time-series data output from the multiple measuring instruments is synchronized based on this rising-edge timing information. In particular, in the present invention, by applying a median filter to each reference data, high-frequency noise can be removed without causing a delay in the rising edge of the signal contained in the reference data. Therefore, according to the present invention, by using the filtered data generated after median filtering, rising-edge timing information can be acquired with high accuracy, and the time-series data output from each measuring instrument can be synchronized with high accuracy.

[0016] (2) In the present invention, by adjusting the time width in the median filter processing so that the signal values ​​included in the steady-state interval of the filtered data remain within a predetermined range over the evaluation time, sudden noises such as impulse noise can be appropriately removed without causing a delay in the rising edge, and as a result, the time-series data of the measuring instrument can be synchronized with high accuracy.

[0017] (3) In the present invention, a signal that changes in a ramp-like manner during the rising edge is used as a reference signal, and filtered data is generated by applying differential processing to the reference data and then applying median filtering. This makes it possible to remove the offset component contained in the measurement data without causing a delay in the rising edge of the measurement data of each measuring instrument, and as a result, the time-series data of the measuring instruments can be synchronized with high accuracy.

[0018] (4) In the present invention, the rise time can be obtained by simple calculation by acquiring the time when the signal value exceeds a predetermined threshold in the filtered data as the rise time.

[0019] (5) In the present invention, a signal that changes in a ramp-like manner in the rising edge is used as a reference signal, and the slope and intercept of a linear function generated based on multiple signal values ​​included in the rising edge of the filtered data are calculated, and the delay time of the rising edge of the filtered data is calculated based on these slope and intercept. According to the present invention, by using the delay time of the rising edge calculated in this way, the time series data of each measuring instrument can be synchronized with even greater accuracy.

[0020] (6) In the present invention, reference data, which is time-series data output from each measuring instrument when a reference signal including a steady-state interval and a rising-edge interval is simultaneously input to the reference signal channels of each of the multiple measuring instruments, and measurement data, which is time-series data output from each measuring instrument when a signal correlated with the state of the test specimen is input to the measurement channels of each of the multiple measuring instruments, are obtained. Furthermore, in the present invention, multiple filtered data is generated by applying median filtering to the multiple reference data, rising-edge timing information is obtained from each of these filtered data, the time-series data output from the multiple measuring instruments is synchronized based on this rising-edge timing information, and the performance of the test specimen is evaluated based on these synchronized measurement data. In particular, in the present invention, by applying median filtering to each reference data, high-frequency noise can be removed without causing a delay in the rising edge of the signal included in the reference data.Therefore, according to the present invention, by using the filtered data generated after median filtering, rising-edge timing information can be obtained with high accuracy, the measurement data output from each measuring instrument can be synchronized with high accuracy, and consequently, the performance of the test specimen can be evaluated with high accuracy. [Brief explanation of the drawing]

[0021] [Figure 1] This figure shows the configuration of a test system according to the first embodiment of the present invention. [Figure 2A]This is a diagram showing an example of a reference signal. [Figure 2B] This is a diagram showing an example of a reference signal. [Figure 3] This is a flowchart showing the specific procedures of the measurement data synchronization method and the test method. [Figure 4] This is a diagram for explaining the effect of median filter processing. [Figure 5] This is an example of plotting the data after the first to fifth filter processes on the same time axis. [Figure 6] This is a flowchart showing the specific procedures of the measurement data synchronization method and the test method according to the second embodiment of the present invention. [Figure 7] This is a diagram for explaining the procedure of calculating the delay time at the rising edge of the data after the first and second filter processes. [Figure 8] This is a diagram showing an example of the output of a measuring instrument when a stepped reference signal is input to the measuring instrument.

Embodiments for Carrying out the Invention

[0022] <First Embodiment> Hereinafter, the first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing the configuration of a test system S to which the measurement data synchronization method and the test method according to this embodiment are applied.

[0023] The test system S uses an electric vehicle V that runs using electric energy, such as a secondary battery electric vehicle, a fuel cell vehicle, a hybrid vehicle, and a plug-in hybrid vehicle, as a test specimen, and is a device for evaluating the performance of this electric vehicle V.

[0024] The test system S comprises a chassis dynamometer system 1 on which the electric vehicle V is mounted, a dilution tunnel 2 through which exhaust gas discharged from the exhaust pipe of the electric vehicle V flows, a group of measuring instruments 3 that generates various data based on detection signals from the electric vehicle V and multiple sensors installed near the electric vehicle V, as well as signals transmitted from the chassis dynamometer system 1, and a data analysis device 5 that performs various calculations using the data generated by the group of measuring instruments 3.

[0025] The chassis dynamometer system 1 comprises a plurality of rollers 11 provided below the electric vehicle V so as to be in contact with the drive wheels of the electric vehicle V on their outer circumferential surfaces, a plurality of dynamometers 12 connected to these rollers 11, and a control device 13 that controls the dynamometers 12 so as to apply an appropriate load to the electric vehicle V running on the rollers 11.

[0026] The driver of the electric vehicle V operates the electric vehicle V according to a driving pattern (e.g., a vehicle speed pattern) displayed on a driver aid (not shown).

[0027] The measuring instrument group 3 comprises multiple measuring instruments 31, 32, 33, 34, and 35 that measure various physical quantities correlated with the state of the electric vehicle V while it is running, and a reference signal generator 38 that generates a reference signal for synchronizing the data measured by these measuring instruments 31 to 35. Each of these measuring instruments 31 to 35 is a multi-channel instrument, having at least a measurement channel and a reference signal channel. The reference signal generator 38 is connected to the reference signal channels of each of the measuring instruments 31 to 35. The reference signal generated by the reference signal generator 38 is input to the reference signal channels of each of the measuring instruments 31 to 35.

[0028] The first measuring instrument 31 is a device primarily used to measure environmental information of the electric vehicle V (e.g., room temperature, humidity, wind speed, and atmospheric pressure). Various sensors necessary for measuring the above environmental information are connected to the measurement channel of the first measuring instrument 31. The first measuring instrument 31 outputs a first data file 31d which includes first reference data, which is time-series data of a reference signal input to the reference signal channel, and first measurement data, which is time-series data of environmental information generated based on the input signal to the measurement channel and synchronized with the first reference data.

[0029] The second measuring instrument 32 is a device primarily used to measure power information (e.g., current, voltage, and energy) of the electric vehicle V and external power supply. Various sensors necessary for measuring the above power information are connected to the measurement channel of the second measuring instrument 32. The second measuring instrument 32 outputs a second data file 32d which includes second reference data, which is time-series data of a reference signal input to the reference signal channel, and second measurement data, which is time-series data of power information generated based on the input signal to the measurement channel and is synchronized with the second reference data.

[0030] The third measuring instrument 33 is a device primarily used to measure driving information (e.g., speed, distance traveled, etc.) and exhaust gas information of the electric vehicle V. The measurement channels of the third measuring instrument 33 are connected to the control device 13 of the dynamometer system 1 and various sensors necessary for measuring exhaust gas information. The third measuring instrument 33 outputs a third data file 33d which includes third reference data, which is time-series data of a reference signal input to the reference signal channel, and third measurement data, which is time-series data of driving information and exhaust gas information generated based on the input signals to the measurement channels and synchronized with the third reference data.

[0031] The fourth measuring instrument 34 is a device for measuring monitor information (e.g., the battery's SOC) that is primarily monitored by the onboard computer of the electric vehicle V. The measurement channel of the fourth measuring instrument 34 is connected to the onboard computer of the electric vehicle V. The fourth measuring instrument 34 outputs a fourth data file 34d which includes fourth reference data, which is time-series data of a reference signal input to the reference signal channel, and fourth measurement data, which is time-series data of monitor information generated based on the input signal to the measurement channel and synchronized with the fourth reference data.

[0032] The fifth measuring instrument 35 is a device primarily used to measure exhaust gas information from the electric vehicle V. A sensor installed in the dilution tunnel 2 is connected to the measurement channel of the fifth measuring instrument 35. The fifth measuring instrument 35 outputs a fifth data file 35d which includes fifth reference data, which is time-series data of a reference signal input to the reference signal channel, and fifth measurement data, which is time-series data of exhaust gas information generated based on the input signal to the measurement channel and synchronized with the fifth reference data.

[0033] The reference signal generator 38 generates a reference signal including at least a steady-state section and a rising-point section in response to an operator's operation, and simultaneously inputs it to the reference signal channels of each measuring instrument 31 to 35. In this embodiment, the case in which the reference signal generator 38 generates a reference signal in response to a manual operation by an operator is described, but the present invention is not limited thereto. The reference signal generator 38 may also generate a reference signal in conjunction with the start signal of the driver aid.

[0034] Figures 2A and 2B show examples of reference signals. Figure 2A shows an example where the signal changes in a step-like manner during the rising edge, and Figure 2B shows an example where the signal changes in a ramp-like manner during the rising edge.

[0035] Returning to Figure 1, the data analysis device 5 is a computer composed of hardware such as a CPU (Central Processing Unit) and other arithmetic processing means, an auxiliary storage means such as an HDD (Hard Disk Drive) or SSD (Solid State Drive) for storing data files 31d to 35d and various programs, a main memory means such as RAM (Random Access Memory) for storing data temporarily required by the arithmetic processing means when executing programs, an operating means such as a keyboard for the operator to perform various operations, and a display means such as a display for showing various information to the operator.

[0036] Figure 3 is a flowchart showing the specific procedures for the measurement data synchronization method and the testing method. Each step shown in the flowchart of Figure 3 is achieved by executing a computer program installed on the data analysis device.

[0037] First, in step ST1, the data analysis device acquires the first to fifth data files output from the first to fifth measuring instruments, and then proceeds to step ST2. As described above, each data file includes the reference data output from each measuring instrument when a reference signal is simultaneously input to the respective reference signal channels of the first to fifth measuring instruments, and the measurement data output from each measuring instrument when a signal correlated with the state of the electric vehicle is input to the respective measurement channels of the first to fifth measuring instruments. In the following, we will explain the case where a signal that changes in a ramp-like manner during the rising edge section is used as the reference signal, as shown in Figure 2B.

[0038] Next, in step ST2, the data analysis device performs differential processing on the first to fifth reference data acquired in step ST1, and then proceeds to step ST3. This removes the offset in the steady-state interval of the first to fifth reference data.

[0039] Next, in step ST3, the data analysis device applies a median filter to the first to fifth reference data, which have undergone differential processing in step ST2, to extract the median within a predetermined time range (2K+1), thereby generating the data after filtering the first to fifth data, and then proceeds to step ST4.

[0040] Here, median filtering is a process that, given a filter input x(n) (where n is an integer) which is a one-dimensional time series data, extracts the median value (the K+1 largest value among x(nK), ..., x(n+K)) within a time width of 2K+1 (where K is an integer), as shown in equation (1) below, and outputs a filter output y(n) which is a one-dimensional time series data. y(n)= MED[x(nK),x(n-K+1),…,x(n),…,x(n+K)] (1)

[0041] Next, in step ST4, the data analysis device determines whether the signal values ​​included in the steady-state interval of the first to fifth filtered data generated in step ST3 under a predetermined time width (2K+1) fall within a range between a positive upper limit and a negative lower limit centered on 0 over a predetermined evaluation time (see Figure 4 below). If the determination result in step ST4 is NO, the data analysis device widens the time width in the median filtering process by counting up the value of integer K (step ST5), and then returns to step ST3. If the determination result in step ST4 is YES, the data analysis device proceeds to step ST6.

[0042] Figure 4 is a diagram illustrating the effect of median filtering in steps ST3 to ST5. Similar to Figure 8, Figure 4 shows an example of reference data (see thin solid line) output from a measuring instrument when a step-shaped reference signal (see thin dashed line) is input to the instrument's reference signal channel. Figure 4 also shows filtered data obtained by applying the processing described in steps ST3 to ST5 to the reference data shown by the thin solid line, with a thick dashed line.

[0043] As shown by the thin solid lines in Figure 4, the first to fifth reference data output from the first to fifth measuring instruments contains harmonic noise. Therefore, as shown in steps ST3 to ST5, by adjusting the time width (2K+1) of the median filter processing so that the signal value included in the steady-state section falls within a predetermined range between a positive upper limit and a negative lower limit centered on value 0, fluctuations in the signal value in the steady-state section can be reduced. Furthermore, as is clear from comparing Figure 4 and Figure 8, in the present invention, by applying median filtering to the reference data to generate filtered data, it is possible to remove harmonic noise while generating filtered data without causing a delay compared to the original reference data.

[0044] Returning to Figure 3, in step ST6, the data analysis device calculates rise time information from each of the first to fifth filtered data calculated in step ST4, and then proceeds to step ST7. Here, rise time information refers to information about the timing at which the signal value rises in each filtered data.

[0045] Figure 5 shows an example of plotting the data after the first to fifth filtering processes on the same time axis. For ease of understanding, the harmonic noise included in each filtered data is omitted in the example shown in Figure 5. As mentioned above, the first to fifth measuring instruments are not operated synchronously, so the rising edge timings of the signal values ​​in each filtered data are inconsistent.

[0046] In step ST6, the data analysis device calculates the first rising edge time t1, second rising edge time t2, third rising edge time t3, fourth rising edge time t4, and fifth rising edge time t5 as rising edge timing information, which are the times when the signal value exceeds the threshold shown by the dashed line in Figure 5 for the data after the first, second, third, fourth, and fifth filtering processes. Therefore, in the example shown in Figure 5, the second reference data and the first reference data can be synchronized by advancing the second reference data by time (t2-t1), the third reference data and the first reference data can be synchronized by delaying the third reference data by time (t1-t3), the fourth reference data and the first reference data can be synchronized by advancing the fourth reference data by time (t4-t1), and the fifth reference data and the first reference data can be synchronized by delaying the fifth reference data by time (t1-t5).

[0047] Returning to Figure 3, in step ST7, the data analysis device synchronizes the first to fifth measurement data acquired in step ST1 based on the first to fifth rise times calculated in step ST6. As described above, the first to fifth reference data are synchronized with the first to fifth measurement data, respectively, so these first to fifth measurement data can be synchronized by using the first to fifth rise times.

[0048] Next, in step ST8, the data analysis device evaluates the performance of the electric vehicle by performing predetermined calculations using the first to fifth measurement data synchronized in step ST7.

[0049] The measurement data synchronization method (steps ST1 to ST7 in Figure 3) and the test method (steps ST1 to ST8 in Figure 3) according to this embodiment provide the following effects. (1) In this embodiment, when a reference signal including a steady-state interval and a rising-edge interval is simultaneously input to the first to fifth measuring instruments, the first to fifth reference data, which are time-series data output from each measuring instrument, are acquired. Median filtering is applied to these first to fifth reference data to generate first to fifth filtered data. The first to fifth rising-edge times are calculated from each of these first to fifth filtered data, and the first to fifth measurement data output from the first to fifth measuring instruments are synchronized based on these first to fifth rising-edge times. In particular, in this embodiment, by applying median filtering to each reference data, high-frequency noise can be removed without causing a delay in the rising edge of the signal contained in each reference data. Therefore, according to this embodiment, by using the first to fifth filtered data generated after median filtering, the first to fifth rising-edge times can be acquired with high accuracy, and the first to fifth measurement data output from the first to fifth measuring instruments can be synchronized with high accuracy.

[0050] (2) In this embodiment, by adjusting the time width in the median filter processing so that the signal values ​​included in the steady-state interval of the data after the first to fifth filtering processes remain within a predetermined range over the evaluation time, sudden noises such as impulse noise can be appropriately removed without causing a delay in the rising edge of the signal values, and as a result, the first to fifth measurement data can be synchronized with high accuracy.

[0051] (3) In this embodiment, a signal that changes in a ramp-like manner during the rising edge is used as a reference signal, and the first to fifth reference data are subjected to differential processing, followed by median filtering to generate the first to fifth filtered data. This makes it possible to remove the offset component contained in the first to fifth measurement data without causing a delay in the rising edge of the first to fifth measurement data of the first to fifth measuring instruments, and as a result, the first to fifth measurement data can be synchronized with high accuracy.

[0052] (4) In this embodiment, the rise time can be obtained by simple calculation by acquiring the time when the signal value exceeds a predetermined threshold in the data after the first to fifth filtering processes as the rise time.

[0053] (5) In this invention, reference data is time-series data output from each of the reference signal channels of multiple measuring instruments when a reference signal including a steady-state interval and a rising-edge interval is simultaneously input to each of the reference signal channels of multiple measuring instruments, and measurement data is time-series data output from each of the measuring instruments when a signal correlated with the state of the test specimen is input to each of the measurement channels of multiple measuring instruments. Furthermore, in this invention, multiple filtered data is generated by applying median filtering to the multiple reference data, rising-edge timing information is obtained from each of these filtered data, the time-series data output from the multiple measuring instruments is synchronized based on this rising-edge timing information, and the performance of the test specimen is evaluated based on these synchronized measurement data. In particular, in this invention, by applying median filtering to each reference data, high-frequency noise can be removed without causing a delay in the rising edge of the signal included in the reference data. Therefore, according to this invention, by using the filtered data generated after median filtering, rising-edge timing information can be obtained with high accuracy, the measurement data output from each measuring instrument can be synchronized with high accuracy, and consequently, the performance of the test specimen can be evaluated with high accuracy.

[0054] <Second Embodiment> Next, a second embodiment of the present invention will be described in detail with reference to the drawings. This embodiment differs from the first embodiment in the processing procedure in the data analysis device.

[0055] Figure 6 is a flowchart showing the specific steps of the measurement data synchronization method and test method according to this embodiment. Steps ST11 and ST17 in Figure 6 are the same as steps ST1 and ST8 in Figure 3, so a detailed explanation is omitted. Below, we will describe the case in which a signal that changes in a ramp-like manner in the rising edge section, as shown in Figure 2B, is used as the reference signal.

[0056] In step ST12, the data analysis device applies the median filtering process described with reference to equation (1) to the first to fifth reference data acquired in step ST11 to generate the first to fifth filtered data, and then proceeds to step ST13.

[0057] Next, in step ST13, the data analysis device determines whether the signal values ​​included in the steady-state interval of the first to fifth filtered data generated in step ST12 under a predetermined time width (2K+1) fall within a range between a positive upper limit and a negative lower limit centered on 0 (see Figure 4 above) over a predetermined evaluation time. If the determination result in step ST13 is NO, the data analysis device widens the time width in the median filtering process by counting up the value of the integer K (step ST14), and then returns to step ST12. If the determination result in step ST13 is YES, the data analysis device proceeds to step ST15. In other words, this embodiment differs from the first embodiment in that it generates the first to fifth filtered data by applying median filtering to the first to fifth reference data without applying differential processing.

[0058] Next, in step ST15, the data analysis device calculates rise time information from each of the first to fifth filtered data calculated in step ST13, and then proceeds to step ST16. More specifically, the data analysis device calculates the delay time of the rise point relative to each predetermined standard from the first to fifth filtered data as rise time information. Hereafter, the delay times of the rise points in the first to fifth filtered data will be referred to as the first to fifth delay times, respectively.

[0059] Figure 7 illustrates the procedure for calculating the delay times Δt1 and Δt2 at the rising edge of the data after the first and second filtering processes. The following explanation will focus on the case where the data after the first filtering process is used as the reference, i.e., where the first delay time Δt1 is set to 0.

[0060] First, the data analysis device extracts signal values ​​within the rising edge interval from each filtered data (in the example in Figure 7, signal values ​​that fall between a lower limit set to a value slightly greater than 0 and an upper limit set to a value greater than this lower limit). Next, the data analysis device approximates the functional shape within the rising edge interval of each filtered data with a linear function characterized by two coefficients (slope and intercept), and calculates the slope and intercept of each linear function using the least squares method with the extracted signal values. Equations (2-1) and (2-2) below show examples in which the signal values ​​(Y1, Y2) in the rising edge interval of the first and second filtered data are approximated as a linear function of time (X1i, X2i). In equations (2-1) and (2-2) below, the coefficients (a1, a2) are the slope and the coefficients (b1, b2) are the intercept. Y1 = a1·X1i + b1 (2-1) Y² = a²·X²i + b² (2-2)

[0061] Next, the data analysis device calculates the delay time of the rising edge relative to a predetermined reference (in this embodiment, the first filtered data) by using the slope and intercept calculated from each filtered data. More specifically, when the first filtered data is used as the reference, the second delay time Δt2 is calculated using the slope (a1, a2) and intercept (b1, b2) calculated earlier by the following equation (3). In the following equation (3), it is assumed that the slope (a2) of the linear function within the rising edge interval of the second filtered data is equal to the slope (a1) of the linear function within the rising edge interval of the first filtered data, but the present invention is not limited to this. For example, the slope of the linear function within the rising edge interval of each filtered data may be the average value of the slopes of each filtered data calculated by the least squares method as described above. Δt²=(b²-b1) / a¹ (3)

[0062] Returning to Figure 6, in step ST16, the data analysis device synchronizes the first to fifth measurement data acquired in step ST11 based on the first to fifth delay times calculated in step ST15. As described above, the first to fifth reference data are synchronized with the first to fifth measurement data, so these first to fifth measurement data can be synchronized by using the first to fifth delay times. That is, as described above, if the first reference data is used as the reference (the first delay time is set to 0), these first to fifth measurement data can be synchronized by advancing the second to fifth measurement data by the second to fifth delay times, respectively.

[0063] The measurement data synchronization method (steps ST11 to ST16 in Figure 6) and the test method (steps ST11 to ST17 in Figure 6) according to this embodiment provide the following effects. (6) In this embodiment, a signal that changes in a ramp-like manner in the rising edge is used as a reference signal, and the slope and intercept of a linear function generated based on multiple signal values ​​included in the rising edge of the filtered data are calculated, and the delay time of the rising edge of the filtered data is calculated based on these slope and intercept. According to this embodiment, by using the delay time of the rising edge calculated in this way, the time-series data of each measuring instrument can be synchronized with even greater accuracy.

[0064] Although one embodiment of the present invention has been described above, the present invention is not limited thereto. Within the scope of the spirit of the present invention, the details of the configuration may be modified as appropriate.

[0065] For example, the above embodiment described a case in which a reference signal generated by the reference signal generation device 38 is input to each measuring instrument 31-35, but the present invention is not limited to this. For example, a vehicle speed detection signal or a vehicle speed command signal output from the driver aid may be input to each measuring instrument 31-35 as a reference signal. [Explanation of Symbols]

[0066] S...Testing System V...Electric vehicle (test specimen) 1…Chassis Dynamometer System 3…Measuring instrument group 31…First measuring instrument 31d...First data file 32... Second measuring instrument 32d...Second data file 33…Third measuring instrument 33d...Third data file 34…Fourth measuring instrument 34d...4th data file 35…5th measuring instrument 35d...5th data file 38...Reference signal generation device 5…Data analysis device (computer)

Claims

1. A measurement data synchronization method for synchronizing time series data output from a plurality of measuring instruments by a computer, comprising: acquiring reference data, which is time-series data output from each of the measuring instruments when a reference signal including a steady section and a rising section is simultaneously input to the plurality of measuring instruments; generating a plurality of filtered data by performing median filtering on the plurality of reference data to extract a median value within a predetermined time span; obtaining rising edge timing information from each of the plurality of filtered data; and synchronizing the time series data output from the plurality of measuring instruments based on the plurality of pieces of rising timing information.

2. 2. The measurement data synchronization method according to claim 1, wherein in the step of generating the filtered data, the time width is adjusted so that a signal value included in the steady section of the filtered data falls within a predetermined range over an evaluation time.

3. In the step of acquiring the reference data, a signal that changes in a ramp shape in the rising section is used as the reference signal; 3. The measurement data synchronization method according to claim 1, wherein in the step of generating the filtered data, the reference data is subjected to differentiation processing and then to the median filtering processing.

4. The measurement data synchronization method according to any one of claims 1 to 3, characterized in that in the step of acquiring the rising timing information, the time at which the signal value in the filtered data exceeds a predetermined threshold is acquired as the rising time.

5. In the step of acquiring the reference data, a signal that changes in a ramp shape in the rising section is used as the reference signal; 3. The measurement data synchronization method according to claim 1, wherein the step of acquiring the rising timing information includes calculating a slope and an intercept of a linear function generated based on a plurality of signal values ​​included in the rising section of the filtered data, and calculating a delay time of the rising point of the filtered data based on the slope and the intercept.

6. A computer program for synchronizing time series data output from a plurality of measuring instruments by a computer, acquiring reference data, which is time-series data output from each of the measuring instruments when a reference signal including a steady section and a rising section is simultaneously input to the plurality of measuring instruments; a step of simultaneously inputting a reference signal including a steady section and a rising section to the plurality of measuring instruments, and acquiring time series data output from each of the measuring instruments as reference data; generating a plurality of filtered data by performing median filtering on the plurality of reference data to extract a median value within a predetermined time span; obtaining rising edge timing information from each of the plurality of filtered data; and synchronizing the time series data output from the plurality of measuring instruments based on the plurality of pieces of rising timing information.

7. A test method for evaluating the performance of a specimen by processing time-series data output from a plurality of measuring instruments using a computer, comprising: a step of acquiring reference data, which is time-series data output from each of the plurality of measuring instruments when a reference signal including a steady section and a rising section is simultaneously input to each of the reference signal channels of the plurality of measuring instruments, and measurement data, which is time-series data output from each of the measuring instruments when a signal correlated with the state of the test piece is input to each of the measurement channels of the plurality of measuring instruments; generating a plurality of filtered data by performing median filtering on the plurality of reference data to extract a median value within a predetermined time span; obtaining rising edge timing information from each of the plurality of filtered data; synchronizing the plurality of measurement data based on the plurality of rise timing information; and evaluating performance of the specimen based on the plurality of synchronized measurement data.

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