Sensor system, failure and deterioration detection method, and program

Abstract

To diagnose failure and deterioration without adding a new HW.SOLUTION: A sensor system includes: a sensor; an analog circuit that performs predetermined analog signal processing on a first signal outputted from the sensor; a power supply part that feeds power to the analog circuit; a digital part including a digital signal processing part that performs predetermined digital signal processing on a second signal outputted from the analog circuit and a feature quantity detection part that detects a feature quantity of the second signal; and a failure and deterioration determination part that determines failure and deterioration of at least one of the analog circuit and the power supply part based on the feature quantity of the second signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sensor system, a failure / deterioration detection method, and a program. [Background technology]

[0002] For example, in fields such as industrial machinery, medical devices, and automobiles, the use of various sensors is increasing, and in addition to indoor use, outdoor use where environmental changes such as temperature, humidity, and vibration are large is also on the rise.

[0003] Furthermore, with the advancement of the circular economy, various sensors are expected to be used beyond their warranty period through second-hand sales and reuse, making it important to diagnose areas where malfunctions or deterioration are occurring.

[0004] Regarding the diagnosis of failures and deterioration, for example, Patent Document 1 describes "an operational amplifier deterioration diagnosis device comprising a band-pass filter that passes predetermined frequency components of the output signal of an operational amplifier to be diagnosed whose input is short-circuited, a calculator that calculates the short-term effective value of the signal obtained from the band-pass filter, and a comparator that compares the output signal from the calculator with a set value."

[0005] Furthermore, for example, Patent Document 2 describes a light-emitting element lighting device that lights up an organic EL light-emitting element, comprising: a temperature detection unit that detects the ambient temperature of the light-emitting element; and a current control unit that controls the current flowing through the light-emitting element to be constant, wherein the current control unit performs protective control by passing a reference current value through the light-emitting element when the temperature detected by the temperature detection unit is below an upper limit value obtained by adding a predetermined temperature to a reference temperature when the light-emitting element is stably lit, and when the detected temperature exceeds the upper limit value, passing a protective current whose value is lower than the reference current value and whose value is to lower the ambient temperature until the temperature detected by the temperature detection unit falls below the reference temperature. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 62-206458 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-137934 Summary of the Invention [Problem to be solved by the invention]

[0007] In the case of the technologies described in Patent Documents 1 and 2, in order to diagnose failures and degradation, it is necessary to add a new failure detection sensor to the device to be diagnosed or connect an external circuit. Therefore, not only does adding a failure detection sensor increase costs, but if the failure detection sensor fails or deteriorates, it becomes impossible to diagnose the failure or degradation of the device to be diagnosed.

[0008] The present invention has been made in consideration of the above points, and aims to make it possible to diagnose failures and deterioration of a device to be diagnosed without adding new HW (hardware). [Means for solving the problem]

[0009] The present application includes a number of means for solving at least part of the above problems, examples of which are as follows.

[0010] In order to solve the above problem, a sensor system according to one embodiment of the present invention includes a sensor, an analog circuit that performs predetermined analog signal processing on a first signal output from the sensor, a power supply unit that supplies power to the analog circuit, a digital unit that includes a digital signal processing unit that performs predetermined digital signal processing on a second signal output from the analog circuit and a feature detection unit that detects a feature of the second signal, and a failure / degradation determination unit that determines failure / degradation of at least one of the analog circuit and the power supply unit based on the feature of the second signal. [Effects of the Invention]

[0011] According to the present invention, it is possible to diagnose failures and deterioration of the device to be diagnosed without adding new HW.

[0012] Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a sensor system according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart illustrating an example of a diagnostic process performed by the sensor system. [Figure 3] FIG. 3 is a diagram showing an example of a table showing the diagnostic criteria for failure and deterioration. [Figure 4] FIG. 4 is a diagram showing an example of the configuration of a sensor system according to the second embodiment of the present invention. [Figure 5] FIG. 5 is a diagram illustrating a first configuration example of an analog circuit. [Figure 6] FIG. 6 is a diagram illustrating the definitions of noise and gain of an operational amplifier that constitutes an analog circuit. [Figure 7] FIG. 7 is a flowchart illustrating an example of a process for identifying which of two operational amplifiers constituting an analog circuit has failed or deteriorated. [Figure 8] FIG. 8 is a diagram for explaining a case where a failure or deterioration of a power supply corresponding to an operational amplifier that constitutes an analog circuit is diagnosed. [Figure 9] FIG. 9 is a diagram showing the results of a simulation of the output offset voltage (saturation voltage) of an operational amplifier in response to degradation of the power supply. [Figure 10] FIG. 10 is a flowchart illustrating an example of a process for diagnosing a failure or deterioration of a power supply that supplies power to an operational amplifier. [Figure 11] FIG. 11 is a diagram illustrating a second configuration example of the analog circuit. [Figure 12] FIG. 12 is a diagram showing an example of the relationship between the change in phase compensation capacitance, the frequency bandwidth, and the noise level. [Figure 13] FIG. 13 is a diagram showing an example of the relationship between the change in resistance, the frequency bandwidth, and the noise level. [Figure 14] FIG. 14 is a flowchart illustrating an example of a process for diagnosing failure and deterioration of resistors and phase compensation capacitors that constitute an analog circuit. [Figure 15] FIG. 15 is a diagram illustrating an example of log data. [Figure 16] FIG. 16 is a diagram showing a display example of a UI (User Interface) screen. DETAILED DESCRIPTION OF THE INVENTION

[0014] Several embodiments of the present invention will be described below with reference to the drawings. Each embodiment is an example for explaining the present invention, and appropriate omissions and simplifications have been made for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural. The position, size, shape, and scope of each component shown in the drawings may not represent the actual position, size, shape, and scope to facilitate understanding of the invention. In all drawings used to explain the embodiments, identical components are generally designated by the same reference numerals, and repeated description of such components will be omitted. Furthermore, in the following embodiments, a component (including an element step, etc.) is not necessarily essential unless otherwise specified or considered to be clearly essential in principle. Furthermore, when a term "consists of A," "composed of A," "having A," or "including A" is used, it does not exclude other elements unless otherwise specified, such as when referring to only that element. Similarly, in the following embodiments, when referring to the shape, positional relationship, etc. of a component, etc., it includes those that are substantially similar or approximate to that shape, etc., unless otherwise specified or considered to be clearly essential in principle. Furthermore, "obtaining" includes, as specific examples, at least the subject generating, calculating, or receiving from outside.

[0015] First Embodiment: Example of Configuration of Sensor System 1 FIG. 1 shows an example of the configuration of a sensor system 1 according to a first embodiment of the present invention. The sensor system 1 detects, for example, photons and displays the detection results as, for example, a sensing image. The sensor system 1 also has a function of diagnosing failures and degradation that have occurred in the components of the sensor system 1. In this specification, failures and degradation refer to a state in which the components of the sensor system 1 are unable to perform all or part of their original performance, and includes disconnections, connection errors, etc.

[0016] The sensor system 1 includes a sensor 10, an analog circuit 20, a power supply unit 30, a digital unit 40, a failure / deterioration determination control unit 50, an input / output unit 60, and a control unit .

[0017] The sensor 10 detects, for example, photons and outputs a signal s1 representing the detection result to the analog circuit 20. The analog circuit 20 performs analog signal processing, such as amplification, on the signal s1 and outputs it to the digital section 40 as a signal s2.

[0018] The power supply unit 30 outputs a control voltage sc1 that both supplies and controls drive power to the sensor 10. The power supply unit 30 also generates and outputs a plurality of control signals ac1 to the analog circuit 20, and supplies a plurality of powers ap1.

[0019] The digital unit 40 is realized by an arithmetic device such as an FPGA (Field Programmable Gate Array), a CPU (Central Processing Unit), or a GPU (Graphics Processing Unit). During normal sensing, the digital unit 40 performs predetermined digital signal processing on the signal s2 and outputs the resulting signal s4 to a sensing result display unit 61 of the input / output unit 60. During fault / degradation determination, the digital unit 40 detects noise superimposed on the signal s2 and a feature amount s5 of the DC level of the signal s2, and outputs the detected feature amount s5 to a fault / degradation determination unit 53 of the fault / degradation determination control unit 50.

[0020] The failure / deterioration determination control unit 50 is realized by adding and executing a predetermined program in the digital unit 40 (such as an FPGA). The failure / deterioration determination control unit 50 controls the failure / deterioration determination in the sensor system 1 and the failure determination control (control of the analog circuit 20 via the power supply unit 30) when making the failure / deterioration determination.

[0021] The failure / deterioration determination control unit 50 includes a threshold value holding unit 52, a failure / deterioration determination unit 53, and a failure determination control unit .

[0022] The threshold value storage unit 52 stores in advance a plurality of threshold values ​​(or reference values) to be compared with the feature value s5, and outputs a threshold value s9 corresponding to at least one of the usage environments 51 and 63 to the failure / deterioration determination unit 53. Here, the usage environment 51 is a numerical value such as temperature, humidity, radiation dose, vibration, etc. detected by a predetermined sensor (not shown). The usage environment 63 is a numerical value such as years of use, temperature, humidity, radiation dose, vibration, etc. input by the user to the UI screen.

[0023] The failure / degradation determination unit 53 compares the feature amount s5 from the digital unit 40 with a threshold value s9 to determine failure / degradation, and outputs a signal s7 indicating the determination result to the failure / degradation location display unit 62. The failure determination control unit 54 generates a control signal s13 for performing failure determination control (control of the analog circuit 20 via the power supply unit 30) when determining failure / degradation, and outputs the control signal s13 to the power supply unit 30.

[0024] The input / output unit 60 displays a UI screen and accepts user input to the UI screen. The input / output unit 60 has a sensing result display unit 61 and a fault / deterioration location display unit 62. The sensing result display unit 61 generates a sensing image based on the signal s4 and displays it on the UI screen. The fault / deterioration location display unit 62 displays faulty or deteriorated locations in the sensor system 1 on the UI screen based on the signal s7 from the fault / deterioration determination unit 53. The usage environment 63 is numerical values ​​such as temperature, humidity, radiation dose, and vibration input by the user to the UI screen.

[0025] The control unit 70 controls the entire sensor system 1.

[0026] The failure / degradation determination control unit 50 is realized by causing a predetermined program to be executed by the device (such as an FPGA) that implements the digital unit 40, and the UI screen that presents the location of the failure or degradation to the user is realized by SW (software). Therefore, the sensor system 1 can diagnose failure or degradation without adding new dedicated HW for diagnosing failure or degradation to the sensing-related configuration (sensor 10, analog circuit 20, power supply unit 30, digital unit 40, input / output unit 60, and control unit 70).

[0027] <Diagnosis processing by sensor system 1> FIG. 2 is a flowchart illustrating an example of the diagnostic process performed by the sensor system 1. As shown in FIG.

[0028] The diagnostic process is continuously executed while the sensor system 1 is performing sensing.

[0029] First, the failure / deterioration determination control unit 50 determines whether or not to execute the failure / deterioration determination (step S1). Specifically, for example, this determination is made by checking whether or not the current date and time is the timing for executing the failure / deterioration determination that is set periodically in advance. Note that this determination may be made by the user instead of the failure / deterioration determination control unit 50.

[0030] Here, if the failure / deterioration determination control unit 50 determines not to perform failure / deterioration determination (NO in step S1), normal sensing processing is performed (step S2), and processing returns to step S1. The normal sensing processing refers to a series of processing in which, for example, photons or the like are detected by the sensor 10, a signal s1 representing the result is converted into a signal s4 via the analog circuit 20 and the digital unit 40, and the sensing result display unit 61 displays, for example, a sensing image.

[0031] Conversely, if the failure / deterioration determination control unit 50 determines that a failure / deterioration determination should be performed (YES in step S1), the digital unit 40 starts acquiring the noise and DC level superimposed on the signal s2 output from the analog circuit 20 as a signal source for failure / deterioration determination (step S3).

[0032] Next, the failure / degradation determination control unit 50 determines whether or not to execute failure determination control when determining failure / degradation (step S4). This determination is made by referring to a table 501 (FIG. 3, described in detail later) previously stored in the failure / degradation determination control unit 50, depending on the circuit, item, etc. to be subjected to the failure / degradation determination.

[0033] Here, if the failure / deterioration judgment control unit 50 determines that failure judgment control should be performed (YES in step S4), the failure judgment control unit 54 generates a control signal s13 for controlling the analog circuit 20 via the power supply unit 30 and outputs it to the power supply unit 30 (step S5).

[0034] Conversely, if the failure / deterioration determination control unit 50 determines not to execute failure determination control (NO in step S4), step S5 is skipped.

[0035] Next, the digital section 40 detects noise in the signal s2 and a feature quantity s5 of the DC level (acquisition of which has started in step S3), and outputs the detected feature quantity s5 to the failure / deterioration determination section 53 (step S6).

[0036] Next, the failure / deterioration determination unit 53 acquires a threshold value s9 corresponding to at least one of the usage environments 51, 63 from the threshold value holding unit 52 (step S7). Next, the failure / deterioration determination unit 53 compares the feature value s5 from the digital unit 40 with the threshold value s9, determines failure / deterioration by referring to the table 501, and outputs a signal s7 indicating the determination result to the failure / deterioration location display unit 62 of the input / output unit 60 (step S8). Next, the failure / deterioration location display unit 62 outputs the failure / deterioration location to the UI screen 1000 (FIG. 16) (step S9).

[0037] Thereafter, the process returns to step S1, and steps S1 and subsequent steps are repeated.

[0038] As described above, according to the first embodiment, by using the noise and DC level of the signal s2 output by the analog circuit 20 as a signal source for determining failure or deterioration, it is possible to determine failure or deterioration without adding new HW for diagnosis.

[0039] 3 shows an example of a table 501 indicating the diagnostic criteria for failure and deterioration in the sensor system 1. It should be noted that the table 501 is held by the failure and deterioration determination control unit 50.

[0040] The table 501 records the failure / degradation items, the locations of the failure / degradation, the signal source used, whether or not there is a failure judgment control, and the feature quantities related to the failure / degradation and the changes that occur during the failure / degradation, in association with the analog circuit 20 and the power supply unit 30 that are the targets of the failure / degradation diagnosis in the sensor system 1.

[0041] For example, when the operational amplifier constituting the analog circuit 20 is to be diagnosed for failure or deterioration, noise is acquired from the signal s2 as the signal source, gain control is executed as the failure determination control, the variance of the noise is detected as a feature, and if the feature is greater than a threshold value, it is determined that the operational amplifier has deteriorated.

[0042] Furthermore, for example, when an LDO (Low Drop Out) element of the power supply unit 30 is to be diagnosed for failure or degradation, the DC level of the signal s2 is acquired as the signal source, DC offset control is executed as failure determination control, the output offset voltage during DC offset control is detected as a feature value, and if the feature value is lower than a threshold value, it is determined that degradation has occurred.

[0043] <Second embodiment: Example of configuration of sensor system 2> 4 shows an example of the configuration of a sensor system 2 according to the second embodiment of the present invention. Note that components common to the sensor system 2 and the sensor system 1 (FIG. 1) are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0044] The sensor system 2 is obtained by adding a sensing result analysis unit 80 to the sensor system 1, and also showing the configurations of the power supply unit 30, the digital unit 40, and the failure / deterioration determination control unit 50 in detail.

[0045] The sensing result analysis unit 80 analyzes the signal s4 input from the digital signal processing unit 41 of the digital unit 40, and outputs the analysis result s6 to the sensing result display unit 61.

[0046] The power supply unit 30 in the sensor system 2 has a power supply 31, an analog control unit 32, and a power supply 35. The power supply 31 outputs a control voltage sc1 to the sensor 10. The analog control unit 32 has a DC offset control unit 33 and a gain control unit 34. The DC offset control unit 33 outputs a control voltage c2 for controlling the DC offset amount to the analog circuit 20. The gain control unit 34 outputs a signal c3 for controlling the gain to the analog circuit 20. The power supply 35 applies a +voltage p1 and a -voltage m1 to active elements such as an operational amplifier that make up the analog circuit 20.

[0047] The digital unit 40 has a digital signal processing unit 41 and a feature detection unit 42. The digital signal processing unit 41 performs predetermined digital signal processing on the signal s2 and outputs the resulting signal s4 to the normal control unit 55 of the failure / deterioration determination control unit 50 and the sensing result analysis unit 80. The digital signal processing unit 41 also obtains noise and a DC level from the signal s2 as signal sources for failure / deterioration determination, and outputs this as a signal s3 to the feature detection unit 42. The feature detection unit 42 detects a feature s5 of the signal s3 and outputs it to the failure / deterioration determination unit 53 of the failure / deterioration determination control unit 50.

[0048] The failure determination control unit 54 of the failure / deterioration determination control unit 50 generates a signal s12 for controlling the analog circuit 20 via the power supply unit 30 when performing failure / deterioration determination, and outputs the signal s12 to the switching unit 56. During normal sensing, the normal control unit 55 generates a signal s11 for controlling the analog circuit 20 via the power supply unit 30 based on the signal s4, and outputs the signal s11 to the switching unit 56. During normal sensing, the switching unit 56 outputs the signal s11 from the normal control unit 55 to the power supply unit 30 as a control signal s13.

[0049] On the other hand, when the switching unit 56 executes the failure determination control for the failure / deterioration determination, it outputs the signal s12 from the failure determination control unit 54 to the power supply unit 30 as a control signal s13.

[0050] In the power supply unit 30 to which the control signal s13 (s12) is input, the analog control unit 32 outputs a control voltage c2 for DC offset control or a control signal c3 for gain control to the analog circuit 20. This causes a change in the signal s2 output from the analog circuit 20, and ultimately in the feature quantity s5, making it possible to determine whether the power supply 35 or the analog circuit 20 has failed or deteriorated.

[0051] <Third embodiment: Failure / deterioration diagnosis of operational amplifiers o1 and o2 constituting the analog circuit 20> Next, a case where the operational amplifiers o1 and o2 constituting the analog circuit 20 are diagnosed for failure and deterioration will be described.

[0052] Figure 5 shows a first configuration example of the analog circuit 20 in the sensor system 2 (Figure 4) and the output destination of the control signal s13 for fault determination control when diagnosing faults and deterioration of the operational amplifiers o1 and o2 that make up the analog circuit 20.

[0053] The first configuration example of the analog circuit 20 is configured by two-stage operational amplifiers o1 and o2 and a resistor R1. A signal s1 output from the sensor 10 is input to the non-inverting input terminal + of the operational amplifier o1, and a control voltage c2 from the DC offset control unit 33 is input to the inverting input terminal - via the resistor R1. The output of the operational amplifier o1 is input to the non-inverting input terminal + of the operational amplifier o2. The operational amplifier o2 outputs a signal s2 to the digital unit 40 in the subsequent stage.

[0054] The control signal s13 for fault determination control is input to the gain control section 34 of the power supply section 30.

[0055] It is known that when operational amplifiers o1 and o2 deteriorate, there is no change in the gain of the operational amplifiers o1 and o2, but noise increases in the signal s2 output from the operational amplifier o2. Therefore, when diagnosing failure or deterioration of the operational amplifiers o1 and o2, the feature detection unit 42 of the digital unit 40 detects the rms (root mean square) value, variance, standard deviation, etc. of the noise in the signal s2 as feature s5, and if feature s5 is larger than a threshold value s9 as a normal value, it is determined that the operational amplifiers o1 and o2 have failed or deteriorated.

[0056] If it is determined that the operational amplifiers o1 and o2 have failed or deteriorated, then in order to further identify which of the operational amplifiers o1 and o2 has failed or deteriorated, the operational amplifier o1 is controlled by the gain control unit 34 of the power supply unit 30 to change the gain as a failure determination control, and a change in the noise of the signal s2 is detected.

[0057] FIG. 6 shows the definitions of the operational amplifiers o1 and o2, the total noise, and the gain used to determine whether the operational amplifiers o1 and o2 are faulty or degraded.

[0058] For example, let us define the initial noise value of the operational amplifier o1 as N1, its gain as G1, the initial noise value of the operational amplifier o2 as N2, its gain as G2, and the total initial noise value of the operational amplifiers o1 and o2 as Nt. Note that the initial noise values ​​N1, N2, and Nt can be easily calculated from the data sheets of the operational amplifiers o1 and o2, etc., and can be considered known because they are measurable. The total noise measurement value can be detected by the feature detection unit 42.

[0059] For example, if the operational amplifiers o1 and o2 fail or deteriorate and the total noise measurement value changes from the initial value Nt to Nt1, the total noise measurement value Nt1 can be calculated using the noise generation amounts N1d and N2d of the operational amplifiers o1 and o2, respectively, using the following equation (1): Nt1=N1d·G1·G2+N2d·G2 ···(1)

[0060] Next, the gain control unit 34 controls the gain of the operational amplifier o1, changing the current gain G1 to G1 / 2, while detecting the total noise measurement value Nt2 without changing the gain G2 of the operational amplifier o2. In this case, the following equation (2) holds for the total noise measurement value Nt2. Nt2=N1d·(G1 / 2)·G2+N2d·G2···(2)

[0061] By treating equations (1) and (2) as simultaneous equations and solving them, equations (3) and (4) for calculating the amount of noise N1d generated by the operational amplifier o1 and the amount of noise N2d generated by the operational amplifier o2 can be derived. N1d=(2 / (G1·G2))·(Nt1-Nt2)···(3) N2d=(1 / G2)·(2·Nt2-Nt1)···(4)

[0062] The noise degradation amounts ΔN1 and ΔN2 in the operational amplifiers o1 and o2 can be calculated by the following equation (5). ΔN1=N1-N1d ΔN2=N2-N2d (5)

[0063] By comparing the noise degradation amounts ΔN1 and ΔN2, it is possible to determine which of the operational amplifiers o1 and o2 has failed or deteriorated. For example, if the noise degradation amount ΔN1 is greater than ΔN2, it can be determined that the operational amplifier o1 has deteriorated. Conversely, if the noise degradation amount ΔN2 is greater than ΔN1, it can be determined that the operational amplifier o2 has deteriorated.

[0064] FIG. 7 is a flowchart showing an example of a process for identifying which of the operational amplifiers o1 and o2 constituting the analog circuit 20 has failed or deteriorated after it has been determined that the analog circuit 20 (operational amplifiers o1 and o2) has deteriorated.

[0065] First, the digital unit 40, which serves as a signal source for failure / deterioration determination, starts acquiring the amount of noise (total noise measurement value) superimposed on the signal s2 output from the analog circuit 20 (step S11).

[0066] Next, the fault judgment control unit 54 generates a control signal s13 for controlling the analog circuit 20 via the power supply unit 30 and outputs it to the gain control unit 34 of the power supply unit 30, and the gain control unit 34 outputs a control signal c3 to the operational amplifier o1 for changing the gain from G1 to G1 / 2 (step S12).

[0067] Next, the feature detector 42 detects the total noise measurement values ​​Nt1 and Nt2 before and after changing the gain of the operational amplifier o1, and calculates the noise generation amounts N1d and N2d using equations (3) and (4) (step S13).

[0068] Next, the failure / deterioration determination unit 53 acquires the total noise initial value Nt as a reference value from the threshold value holding unit 52 (step S14).

[0069] Next, the failure / degradation determination unit 53 calculates the noise degradation amounts ΔN1 and ΔN2 using equation (5), and identifies which of the operational amplifiers o1 and o2 has failed or deteriorated by comparing the magnitudes of the noise degradation amounts ΔN1 and ΔN2 (step S15).

[0070] As described above, according to this embodiment, when the analog circuit 20 configured with two-stage operational amplifiers o1 and o2 has failed or deteriorated, the gain of the first-stage operational amplifier o1 is changed to calculate the noise degradation amounts ΔN1 and ΔN2 of the operational amplifiers o1 and o2, and by comparing these amounts, it is possible to identify which of the operational amplifiers o1 and o2 has failed or deteriorated.

[0071] As a modified example, instead of changing the gain of the operational amplifier o1, the gain of the operational amplifier o2 may be changed. Also, even if the analog circuit 20 is configured with three or more stages of operational amplifiers, a faulty or deteriorated operational amplifier can be identified in a similar manner.

[0072] Note that the gain control for the operational amplifier provided in the analog circuit 20 is a function provided in a general analog circuit, so there is no need to add new hardware or the like for gain control for the operational amplifier.

[0073] <Fourth embodiment: Failure / deterioration diagnosis of the power supply 35 that supplies power to the analog circuit 20> Next, a case where a failure or deterioration of the power supply 35 that supplies power to the analog circuit 20 is diagnosed will be described.

[0074] 8 shows a first configuration example of the analog circuit 20 in the sensor system 2 (FIG. 4) and the output destination of the control signal s13 for fault determination control when diagnosing faults and degradation in the power supply 35. The analog circuit 20 is configured by two-stage operational amplifiers o1 and o2, as in the case of FIG. 5. The control signal s13 is input to the DC offset control unit 33 of the power supply unit 30.

[0075] The power supply 35 that supplies power to the analog circuit 20 is composed of, for example, an LDO (Low Drop Out) element. It is known that the output voltage of an LDO element drops when it breaks down or deteriorates. For example, a + voltage that is normally +5V may drop below +5V when it deteriorates, and a - voltage that is normally -5V may drop above -5V when it deteriorates.

[0076] Therefore, in this embodiment, in order to determine whether the output voltage from the LDO element has dropped, the DC offset control unit 33 of the power supply unit 30 is controlled by a control signal s13 from the fault determination control unit 12 to use a control voltage c2. Specifically, when the control voltage c2 is swung to a value greater than or equal to the width of the output voltage of the LDO element (for example, ±5 V), the output voltages of the operational amplifiers o1 and o2 saturate after swinging to the same values ​​as the +voltage p1 (for example, +5 V) and -voltage m1 (for example, −5 V) applied from the power supply 35.

[0077] FIG. 9 shows the results of simulating the output offset voltage (saturation voltage) of the operational amplifier o1 when the positive voltage p1 drops from +5V to +3V due to degradation of the power supply 35.

[0078] When the power supply 35 is in a normal state, the +voltage p1 is +5 V, and an output offset voltage of +5 V is obtained. However, when the power supply 35 is in a deteriorated state, the +voltage p1 gradually decreases, and the simulation results show that the output offset voltage also decreases accordingly.

[0079] Therefore, in this embodiment, if the feature detector 42 detects this saturation voltage (i.e., DC offset voltage), it is possible to detect the +voltage p1 and -voltage m1 from the power supply 35. Then, by comparing the detected +voltage p1 and -voltage m1 from the power supply 35 with the LDO specifications (e.g., ±5V), it is possible to determine the degradation of the output voltage of the LDO element that constitutes the power supply 35.

[0080] FIG. 9 is a flowchart showing an example of a process for diagnosing whether or not the power supply 35 (the LOD element thereof) that supplies power to the analog circuit 20 has failed or deteriorated.

[0081] First, the digital section 40 starts acquiring the DC level of the signal s2 output from the analog circuit 20 as a signal source for failure / deterioration determination (step S21).

[0082] Next, the fault judgment control unit 54 generates a control signal s13 for controlling the analog circuit 20 via the power supply unit 30 and outputs it to the DC offset control unit 33 of the power supply unit 30, and the DC offset control unit 33 oscillates the control voltage c2 for the operational amplifier o1 by a large amount greater than or equal to the initial value range (e.g., ±5 V) of the output voltage of the power supply 35 (step S22).

[0083] Next, the feature detector 42 detects the saturation voltage (DC offset voltage) of the signal s3 (step S23).

[0084] Next, the failure / deterioration determination unit 53 acquires the initial value (for example, ±5 V) of the output voltage of the power supply 35 from the threshold value holding unit 52 (step S24).

[0085] Next, the failure / degradation determination unit 53 diagnoses whether the power supply 35 has failed or deteriorated based on whether the saturation voltage detected in step S23 is lower than the initial value of the output voltage of the power supply 35 acquired in step S24 (step S25).

[0086] As described above, according to this embodiment, the control voltage c2 for the operational amplifier o1 is oscillated to a value equal to or greater than the initial value width (for example, ±5 V) of the output voltage of the LOD element constituting the power supply 35, thereby making it possible to detect the saturation voltage of the signal s2, i.e., the current output voltage of the power supply 35. By comparing this with the initial value, it is possible to diagnose a failure or degradation of the power supply 35.

[0087] Note that DC offset control for the operational amplifier provided in the analog circuit 20 is a function provided in a general analog circuit, so there is no need to add new hardware or the like for DC offset control for the operational amplifier.

[0088] Fifth Embodiment: Failure / Deterioration Diagnosis of Resistors and Phase Compensation Capacitors Constituting the Analog Circuit 20 Along with the Operational Amplifiers o1 and o2 Next, a case where failure and deterioration of the resistors and phase compensation capacitors that constitute the analog circuit 20 together with the operational amplifiers o1 and o2 will be diagnosed will be described.

[0089] 11 shows a second configuration example of the analog circuit 20 in the sensor system 2. The second configuration example of the analog circuit 20 is configured by two-stage operational amplifiers o1 and o2, similar to the first configuration example (FIG. 5, etc.). Furthermore, the second configuration example has resistors R11, R12, R21, and R22 that determine the gain and bandwidth of the operational amplifiers o1 and o2, and phase compensation capacitors C11 and C12.

[0090] Figure 12 shows the frequency characteristics of noise in the signal s2 output from the operational amplifier o2 when the phase compensation capacitance C11 is changed. As shown in the figure, when the capacitance value of the phase compensation capacitance C11 increases, the frequency bandwidth becomes narrower than normal. Conversely, when the capacitance value of the phase compensation capacitance C11 decreases, the frequency bandwidth becomes wider than normal.

[0091] Figure 13 shows the frequency characteristics of noise in signal s3 output from operational amplifier o2 when resistors R11 and R12 are changed. As shown in the figure, when the resistance value of resistor R12 increases or the resistance value of resistor R11 decreases, the frequency bandwidth becomes narrower than normal and the noise level increases. Conversely, when the resistance value of resistor R12 decreases or the resistance value of resistor R11 increases, the frequency bandwidth becomes wider than normal and the noise level decreases.

[0092] Therefore, in this embodiment, when the resistors R11, R12, R21, and R22 and the phase compensation capacitors C11 and C12 fail or deteriorate, their values ​​change, causing fluctuations in the frequency characteristics and noise level of the noise in the signal s2, and this is utilized to diagnose failure or deterioration of the resistors R11, R12, R21, and R22 and the phase compensation capacitors C11 and C12.

[0093] 14 is a flowchart showing an example of a process for diagnosing whether or not the resistors and capacitors that constitute the analog circuit 20 together with the operational amplifiers o1 and o2 have failed or deteriorated. Note that no failure determination control is performed in this process.

[0094] First, the digital section 40 starts acquiring noise from the signal s2 output from the analog circuit 20 as a signal source for failure / deterioration determination (step S31).

[0095] Next, the feature detector 42 detects the frequency bandwidth as the feature of the signal s3 (step S32).

[0096] Next, the failure / deterioration determination unit 53 acquires the initial values ​​of the frequency bandwidth and the noise level as the feature quantities of the signal s3 from the threshold value holding unit 52 (step S33).

[0097] Next, the failure / degradation determination unit 53 diagnoses whether the resistors and phase compensation capacitors that constitute the analog circuit 20 together with the operational amplifiers o1 and o2 have failed or deteriorated, based on whether the frequency band and noise level of the signal s3 detected in step S32 have changed from the initial values ​​acquired in step S33 (step S34).

[0098] As described above, according to this embodiment, the control voltage c2 for the operational amplifier o1 is oscillated to a value equal to or greater than the initial value width (for example, ±5 V) of the output voltage of the LOD element constituting the power supply 35, thereby making it possible to detect the saturation voltage of the signal s2, i.e., the current output voltage of the power supply 35. By comparing this with the initial value, it is possible to diagnose a failure or degradation of the power supply 35.

[0099] Sixth Embodiment: Recording of Log Data In the first to fifth embodiments described above, the feature amount of the signal s2 is detected each time a failure / degradation diagnosis is performed. However, the feature amount of the signal s2 may be detected in parallel with the normal sensing process and stored as log data. The log data may then be read out when a failure / degradation diagnosis is performed. The process of storing the detected feature amount as log data may be performed, for example, by the feature amount detection unit 42 or the control unit 70.

[0100] FIG. 15 shows an example of the detection timing of the feature amount of the signal s2 and the contents of the log data.

[0101] The detection of the feature amount of the signal s2 may be performed, for example, by providing a non-measurement period between periodic measurements performed by the sensor 10 and performing the detection for each Δ period of the non-measurement period.

[0102] The log data records the rms value, variance, standard deviation, etc. of noise, saturation voltage (DC offset voltage), noise frequency bandwidth, noise level, etc., which are used as feature quantities in the third to fifth embodiments. The log data also records the rate of change from the initial value of each feature quantity, etc.

[0103] <Seventh embodiment: Example of UI screen display> FIG. 16 shows an example of a UI screen 1000 displayed on the input / output unit 60. As shown in FIG.

[0104] The UI screen 1000 includes an operating environment input field 1001, a sensing result display field 1002, a log data display field 1003, and a fault / degradation location display field 1004.

[0105] The usage environment input field 1001 is for receiving the usage environment input by the user. In this figure, the input of the sensor aging deterioration degree is received as the usage environment. This allows the user to set the usage environment of the sensor system.

[0106] The sensing result display field 1002 displays, for example, a sensing image and output from the sensing result analysis unit 80. This allows the user to check the normal sensing results and their analysis results.

[0107] 15 and a graph showing the change in the feature amount based on the log data are displayed in the log data display field 1003. This allows the user to visually confirm the change and easily grasp the degree of deterioration. Note that if the change in the feature amount exceeds a predetermined threshold, the log data display field 1003 may highlight that portion.

[0108] The fault / degradation location display field 1004 displays a circuit diagram of the sensor system, and highlights the locations diagnosed as faulty or degraded (in this figure, they are highlighted by encircling them with a dashed circle). This allows the user to easily visually identify the faulty or degraded locations.

[0109] The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with or add to the configuration of another embodiment. [Explanation of symbols]

[0110] 1,2... Sensor system, 10... Sensor, 12... Fault determination control unit, 20... Analog circuit, 30... Power supply unit, 31... Power supply, 32... Analog control unit, 33... DC offset control unit, 34... Gain control unit, 35... Power supply, 40... Digital unit, 41... Digital signal processing unit, 42... Feature detection unit, 50... Fault / deterioration determination control unit 51... Operating environment, 52... Threshold value holding section, 53... Failure / deterioration determination section, 54... Failure determination control section, 55... Normal control section, 56... Switching section, 60... Input / output section, 61... Sensing result display section, 62... Failure / deterioration location display section, 63... Operating environment, 70... Control section, 80... Sensing result analysis section, 501... Table, 1000... UI screen

Claims

1. A sensor, an analog circuit that performs predetermined analog signal processing on the first signal output from the sensor; a power supply unit that supplies power to the analog circuit; a digital unit including a digital signal processing unit that performs predetermined digital signal processing on the second signal output from the analog circuit, and a feature amount detection unit that detects a feature amount of the second signal; a failure / degradation determination unit that determines failure / degradation of at least one of the analog circuit and the power supply unit based on the feature amount of the second signal; A sensor system comprising:

2. 2. The sensor system of claim 1, the digital section is realized by a computing device; The failure / deterioration determination unit is realized by adding a predetermined program to the arithmetic device and executing it. Sensor system.

3. 2. The sensor system of claim 1, a failure determination control unit that controls the analog circuit via the power supply unit when the failure / degradation determination unit determines failure / degradation. Sensor system.

4. The sensor system of claim 3, The analog circuit is composed of a two-stage operational amplifier, the failure determination control unit changes the gain of one of the two-stage operational amplifiers, the feature amount detection unit detects feature amounts related to noise in the second signal before and after the gain is changed by the failure determination control unit; The failure / deterioration determination unit identifies a failed / deteriorated operational amplifier from among the two stages of operational amplifiers based on the feature amount related to noise in the second signal before and after the gain is changed. Sensor system.

5. The sensor system of claim 3, The analog circuit is composed of a two-stage operational amplifier, The failure determination control unit varies a DC offset of the operational amplifier, the characteristic amount detection unit detects, as the characteristic amount, a saturation voltage of the second signal while the DC offset is varied by the failure determination control unit; The failure / degradation determination unit determines whether the power supply unit has a failure or degradation based on a saturation voltage of the second signal detected as the characteristic amount. Sensor system.

6. 2. The sensor system of claim 1, the analog circuit is composed of a two-stage operational amplifier, a resistor that determines the gain of the operational amplifier, and a phase compensation capacitor; the feature detection unit detects a frequency bandwidth of noise in the second signal as the feature; The failure / degradation determination unit determines failure / degradation of at least one of the resistor and the phase compensation capacitor based on the frequency bandwidth of noise in the second signal detected as the feature amount. Sensor system.

7. 2. The sensor system of claim 1, The feature amount detection unit detects a feature amount of the second signal when the sensor is not measuring, and stores the detected feature amount as log data. Sensor system.

8. 8. The sensor system of claim 7, an input / output unit that displays a UI screen that displays at least one of the output of the digital signal processing unit, the log data, and the fault / deterioration location determined by the fault / deterioration determination unit. Sensor system.

9. A sensor, an analog circuit that performs predetermined analog signal processing on the first signal output from the sensor; a power supply unit that supplies power to the analog circuit; a digital unit that performs predetermined digital signal processing on the second signal output from the analog circuit, by the digital unit, a detecting step of detecting a feature amount of the second signal; a failure / degradation determination step of determining failure / degradation of at least one of the analog circuit and the power supply unit based on the feature amount of the detected second signal; A failure / deterioration detection method including:

10. A sensor, an analog circuit that performs predetermined analog signal processing on the first signal output from the sensor; a power supply unit that supplies power to the analog circuit; a calculation device as a digital unit that performs predetermined digital signal processing on the second signal output from the analog circuit, a detecting step of detecting a feature amount of the second signal; a failure / degradation determination step of determining failure / degradation of at least one of the analog circuit and the power supply unit based on the feature amount of the detected second signal; A program that executes the following.

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