Sensor system and control method with evaluation confirmation delay

Abstract

Conventional MEMS sensors typically convert observed values ​​into physical quantities and output them immediately, which leads to problems such as false detections and misattributions due to disturbances, drift, nonlinear responses, or temporary instability. Furthermore, it is difficult to explain the reliability of the output values ​​after the fact, posing challenges to their application in industrial fields where safety and accountability are required. [Solution] The present invention generates multiple evaluation indices based on observed values ​​obtained from a sensor, and delays the definitive output of physical quantities until the consistency and stability of these indices satisfy predetermined conditions. By converting to physical quantities and outputting only when the definitive conditions are met, and performing additional observations when the conditions are not met, false detections and misattributions are suppressed, and highly reliable sensor output is achieved.

Description

Technical Field

[0001] The present invention relates to a sensor system and a control method thereof, and particularly to a technique for controlling the evaluation and determination processing of measurement results in MEMS sensors, nanosensing devices, sensor arrays, etc. It relates to a technique for controlling the evaluation and determination processing of measurement results.

Background Art

[0002] In conventional high-sensitivity sensors, the measured value is immediately converted into a single physical quantity after acquisition, and has been used as a confirmed value for output, recording, or control. However, in MEMS sensors and nanoscale sensing, due to the influence of temperature drift, encapsulation stress, surface adsorption, non-linear response, 1 / f noise, etc., correlation components not caused by the measurement target are likely to be mixed in during the evaluation process. As a result, once an evaluation result including misattribution is confirmed, there has been a problem that it becomes difficult to correct it later.

Summary of the Invention

Problems to be Solved by the Invention

[0003] An object of the present invention is to suppress the problem of misattribution caused by the fixation of correlation components other than the measurement target during the evaluation process. Another object is to suppress an increase in misattribution accompanying an increase in the degree of freedom of evaluation in high-dimensional measurement such as a sensor array. It is an object to suppress an increase in misattribution accompanying an increase in the degree of freedom of evaluation.

Means for Solving the Problems

[0004] The sensor system according to the present invention includes a sensor unit that detects a physical quantity, an evaluation index generation unit that generates a plurality of evaluation indexes from the output of the sensor unit, ​A holding unit for holding the plurality of evaluation indicators, Determine whether or not to finalize the evaluation result based on the aforementioned multiple evaluation indicators. A determination condition unit, According to the determination result of the aforementioned condition determination unit To execute or delay the confirmation of the aforementioned evaluation results. Evaluation confirmation control unit, It is characterized by having the following features. [Effects of the Invention]

[0005] According to the present invention, by delaying the determination of the evaluation results until predetermined conditions are met, This can prevent correlation components other than the target of measurement from becoming fixed in the evaluation results. This enables long-term stable measurement and sensor arrays. This can improve operational reliability. [Brief explanation of the drawing]

[0006] [Figure 1] Figure 1 is a block diagram showing the overall configuration of a sensor system according to one embodiment of the present invention, illustrating the functional relationships between the sensor unit, evaluation index generation unit, evaluation index holding unit, determination condition determination unit, and evaluation determination control unit. [Figure 2] Figure 2 is a flowchart illustrating an example of evaluation confirmation delay control. It shows the process flow, which involves observation, evaluation index generation, evaluation index retention, and confirmation condition determination. If the confirmation condition is not met, additional observations are performed, and the evaluation result is confirmed only if it is met. [Figure 3] Figure 3 is an explanatory diagram illustrating an example of a difference evaluation index using a reference structure. It shows a configuration in which the difference frequency Δf, defined as the difference between the resonant frequency of the main sensor and the resonant frequency of the reference sensor, is stored as an evaluation index and converted to a physical quantity only when certain conditions are met. [Modes for carrying out the invention]

[0007] The following describes embodiments of the present invention with reference to the drawings. Note that these embodiments are not limiting to the present invention and can be modified as appropriate within the scope of the claims.

[0008] [Definitions of Terms and Symbols] Observed values ​​refer to raw data such as voltage, frequency, phase, current, or resistance acquired from the sensor unit. Evaluation indices refer to multiple feature quantities calculated from the observed values ​​and used to determine whether a determination is possible or not. Determination means outputting the final value as a single physical quantity (e.g., mass, concentration, or force). Delay means continuing to maintain the evaluation indices and perform additional observations without performing the determination. A reference structure refers to a reference sensor that is subjected to the same level of disturbance as the main sensor and has low sensitivity to the object being measured. Δf refers to the difference between the resonance frequency f_main of the main sensor and the resonance frequency f_ref of the reference sensor (Δf = f_main - f_ref). [Examples]

[0009] [Example 1] Evaluation confirmation delay in a resonant MEMS mass sensor As shown in Figure 1, the sensor system of this embodiment comprises a main resonator made of a resonant MEMS and a reference resonator arranged in parallel therewith. The evaluation index generation unit generates indices showing the difference frequency Δf, Q value change ΔQ, amplitude change, and nonlinear indications by a frequency tracking circuit or frequency sweep measurement. The retention unit retains the evaluation index as time-series data. The difference frequency Δf is calculated as the difference between the resonant frequency f_main of the main resonator and the resonant frequency f_ref of the reference resonator. The Q-factor change ΔQ is calculated as the difference between the Q-factor Q_main of the main resonator and the Q-factor Q_ref of the reference resonator. The confirmation condition determination unit determines whether the evaluation result can be confirmed based on the following conditions: the variation of Δf within a predetermined time window is below a predetermined threshold, the sign relationship between Δf and ΔQ satisfies a predetermined condition, and the nonlinear indication is within a predetermined range. Until the determination condition is satisfied, the evaluation determination control unit does not perform mass conversion. After the determination condition is satisfied, the adsorbed mass is calculated based on Δf and the effective mass, and the calculation result is output. If the determination condition is not satisfied, additional observations with changed measurement conditions are executed.

[0010] [Example 2] Stepwise Evaluation in Sensor Array In this example, a MEMS sensor array composed of a plurality of sensor elements is used. An evaluation index is generated for each sensor element, and stepwise determination is performed in the order of element unit, cluster unit, and overall unit. Even if a local determination candidate is obtained, if spatial consistency is not ensured, the determination is delayed and additional observations are performed.

[0011] [Example 3] Application Example to Gas Sensor In this example, a gas sensor having a sensitive film formed on a MEMS heater is used. The evaluation index generation unit generates a plurality of indexes such as not only the resistance value but also the response curve to a temperature sweep and the response time constant. Concentration conversion is not performed until these indexes satisfy the predetermined conditions.

[0012] [Example 4] Configuration Including Learning Device <​​​​​​​​​​​​​​​​The present invention provides a configuration for MEMS sensors or nanoscale sensors that delays the determination of observation results and outputs a physical quantity only when the consistency and stability of multiple evaluation indicators are satisfied, thereby suppressing false detections, misattributions, and the output of unstable conversion results.

[0015] Therefore, the present invention is applicable to various MEMS devices such as resonant MEMS mass sensors, gas sensors, chemical sensors, biosensors, pressure sensors, acceleration sensors, and gyro sensors, and can be widely used in fields such as semiconductor manufacturing equipment, environmental measurement equipment, industrial process control equipment, automotive sensors, medical diagnostic equipment, and analytical and measuring instruments.

[0016] Furthermore, because the present invention enables control that allows for additional observations while maintaining an undetermined evaluation state, it is particularly effective in industrial fields where accountability and safety regarding sensor output are important, and makes it possible to implement sensor systems that "treat an undetermined state as a safe behavior," which was previously difficult.

[0017] Therefore, the present invention can be widely applied to applications ranging from mass-produced MEMS sensors to industrial applications, research applications, and social infrastructure applications requiring high reliability, and its industrial applicability is extremely high. [Explanation of Symbols]

[0018] 1. Sensor System 2. Recovery Unit 3. Main sensor (main resonator) 4. Reference sensor (reference resonator) 5. Evaluation Index Generation Unit 6 Holding part 7 Determined condition judgment section 8. Evaluation Confirmation Control Unit 9. Additional Observation Control Unit 10 Output section f_main Main sensor resonant frequency f_ref Resonant frequency of the reference sensor Δf Difference frequency (f_main - f_ref) Q_main: Q value of the main sensor Q_ref: Q value of the reference sensor ΔQ Q value change (Q_main - Q_ref) Tw time window σ_f Standard deviation of the difference frequency θ_f is the threshold for frequency stability.

Claims

1. A recovery unit that detects physical quantities, An evaluation index generation unit that generates multiple evaluation indices from the output of the sensor unit, A holding unit for holding the plurality of evaluation indicators, A determination condition determination unit that determines whether or not to finalize the evaluation result based on the plurality of evaluation indicators, An evaluation confirmation control unit that executes or delays the confirmation of the evaluation result according to the determination result of the confirmation condition determination unit, A sensor system characterized by comprising the following features.

2. The aforementioned evaluation metrics are generated based on different time scales. The sensor system according to claim 1.

3. The aforementioned evaluation index is generated based on different physical modes. The sensor system according to claim 1 or 2.

4. The aforementioned evaluation index is generated based on the difference using the reference structure. The sensor system according to any one of claims 1 to 3.

5. The determination condition unit determines the consistency between the evaluation indicators based on the following Determine whether the evaluation result can be finalized. The sensor system according to any one of claims 1 to 4.

6. The determination of the condition based on the time stability of the evaluation index Determine whether the evaluation result can be finalized. The sensor system according to any one of claims 1 to 5.

7. The evaluation confirmation control unit, during the period in which the confirmation of the evaluation result is delayed, No conversion process to a single physical quantity is performed. The sensor system according to any one of claims 1 to 6.

8. The evaluation confirmation control unit continues until the confirmation condition is met. Control the sensor unit to perform additional observations. The sensor system according to any one of claims 1 to 7.

9. The aforementioned additional observations involved extending the measurement time, changing the excitation conditions, or including frequency sweeps, The sensor system according to claim 8.

10. The evaluation index generation unit uses a frequency tracking method and a frequency sweep method. Generate evaluation metrics based on at least one of the following: The sensor system according to any one of claims 1 to 9.

11. A sensor array comprising multiple sensor elements, The aforementioned determination condition unit and evaluation determination control unit The evaluation results are determined based on a phased evaluation. The sensor system according to any one of claims 1 to 10.

12. The aforementioned stepwise evaluation includes evaluation at the element level, evaluation at the cluster level, and overall evaluation, The sensor system according to claim 11.

13. The aforementioned confirmation condition determination unit determines that the confidence interval of the estimated value is less than or equal to a predetermined value. Determine whether the evaluation result can be finalized. The sensor system according to any one of claims 1 to 12.

14. The evaluation index generation unit or the definitive condition determination unit includes a learning device. The update of the learning device will be carried out after the evaluation results are finalized. The sensor system according to any one of claims 1 to 13.

15. A control method for a sensor system according to any one of claims 1 to 14, A process of detecting a physical quantity using a sensor, The process of generating multiple evaluation metrics, A step of retaining the aforementioned evaluation index, A process in which the evaluation result is determined only when the conditions for determination are met, A control method characterized by including

16. The sensor system according to any one of claims 1 to 14, It is characterized by being applicable to MEMS sensors, nanosensing devices, or sensor arrays. Sensor system.

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