Deformation amount detecting device

Abstract

An object of the present application is to provide a deformation amount detecting device which can suppress power consumption by itself judging a timing of measuring a strain and a timing of transmitting a measurement result thereof. The deformation amount detecting device of the present application includes a state judging section which judges a motion state of an object from a characteristic quantity of a temporal change of a measurement signal, acquires the measurement signal at a first sampling rate and calculates the deformation amount when the object is in a stopped state, and acquires the measurement signal at a second sampling rate higher in frequency than the first sampling rate and calculates the deformation amount when the object is in a transition state which shifts from the stopped state to a moving state (see Fig. 1).

Description

Technical Field

[0001] This invention relates to a deformation detection device for detecting the amount of deformation (strain) of an object. Background Technology

[0002] Tire strain sensors are used to detect vehicle slippage by detecting tire deformation. The tire strain sensor is mounted on the inside of the tire and therefore typically uses a battery as its power source. For continuous detection, the tire strain sensor must operate continuously for at least the duration of the tire replacement cycle.

[0003] Existing tire strain sensors continuously measure strain and transmit results regardless of the vehicle's driving state (e.g., while driving, stationary, or starting). Therefore, they consume power even in situations where measuring tire strain is less necessary, such as when the vehicle is stationary. Consequently, the sensor's operating time may be shortened.

[0004] Patent Document 1 below describes a technique for suppressing battery consumption of sensors mounted on wheels. This document addresses the technical problem of "providing a vehicle control device capable of suppressing battery consumption of sensor units mounted on wheels for detecting tire pressure and acceleration," and describes a vehicle control device comprising: "a sensor unit 4 mounted on each wheel 2, detecting tire pressure and acceleration applied to the wheel, transmitting signals regarding the tire pressure and acceleration applied to the wheel to the vehicle body; transmission and reception units 6 and 20 disposed on the vehicle body, determining and transmitting a transmission status including transmission content and transmission rate from the sensor unit to the sensor unit, and receiving the signals from the sensor unit; a tire pressure warning device 22 that determines the tire pressure of each wheel based on the signals regarding the tire pressure, and issues an alarm when the tire pressure of any wheel exceeds a predetermined range; and a control characteristic changing unit 30 that changes the vehicle's control characteristics based on the signals regarding the acceleration." (See abstract).

[0005] Patent Document 2 also describes a technique for suppressing battery consumption of sensors mounted on wheels. This document addresses the technical problem of "being able to suppress battery consumption and also send tire pressure information of the spare wheel to the tire pressure notification device," and describes a technique whereby "the transmission control unit of the sensor unit periodically transmits wheel information (S13-S16) when the acceleration Gx detected by the acceleration sensor is greater than the driving determination threshold 5G. When the acceleration Gx is less than or equal to the driving determination threshold 5G, the transmission control unit accumulates points P corresponding to the acceleration Gx according to a preset set period (S18-S24), and sends wheel information (S25-S28) when the accumulated value of points P within the set time is greater than the actual driving determination threshold 10." (See abstract for reference).

[0006] Patent Document 1: Japanese Patent Application Publication No. 2003-252014

[0007] Patent Document 2: Japanese Patent Application Publication No. 2016-144961 Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] Patent Document 1 describes a technology related to a vehicle control device. Specifically, the technology described in this document is established by instructing the sensor's operating frequency from the vehicle control device. Therefore, in environments where such instruction cannot be obtained from the vehicle control device, it is difficult to extend the sensor's operating time. In other words, it can be argued that if the sensor itself can determine the operating frequency, then even without receiving such instruction from outside the sensor, the operating time can be extended.

[0010] Patent Document 2 describes a technique that uses acceleration Gx detected by an accelerometer to determine the frequency of transmitting wheel information. Therefore, an accelerometer is required in addition to the strain sensor, or communication with an existing accelerometer is necessary. This necessitates the design of a separate communication interface between the strain sensor and the accelerometer, increasing design costs and processing load. It is reasonable to assume that if the strain sensor itself could determine the frequency of motion, this burden could be alleviated.

[0011] The present invention was made in view of the technical problems described above, and aims to provide a deformation detection device that can suppress power consumption by determining the timing of strain measurement and the timing of sending the measurement results.

[0012] Technical means for solving technical problems

[0013] The deformation detection device of the present invention includes a state determination unit that determines the motion state of an object based on the characteristic quantity of the time-varying measurement signal. When the object is in a stopped state, the measurement signal is acquired at a first sampling rate and the deformation is calculated. When the object is in a transition state from the stopped state to a moving state, the measurement signal is acquired at a second sampling rate with a frequency higher than the first sampling rate and the deformation is calculated.

[0014] The effects of the invention

[0015] According to the deformation detection device of the present invention, the device itself determines the time of strain measurement and the time of transmitting the measurement result. Therefore, power consumption can be suppressed without obtaining indications or measurement results from external systems or external sensors. Attached Figure Description

[0016] Figure 1 This is a block diagram showing the structure of the deformation detection device 1 according to Embodiment 1.

[0017] Figure 2 This is a diagram illustrating the state transitions of the mode in which the signal processing unit 12 samples the measurement signal.

[0018] Figure 3 This is a diagram illustrating the time-dependent change of the measurement signal output by the strain measuring element 11.

[0019] Figure 4 This is an example of the peak waveform of the measurement signal extracted by the feature extraction unit 125 in the start-up state. Detailed Implementation

[0020] <Implementation Method 1>

[0021] Figure 1 This is a block diagram showing the structure of the deformation detection device 1 according to Embodiment 1 of the present invention. The deformation detection device 1 is a device for detecting the deformation of an object. For example, by installing the deformation detection device 1 on the inner surface of a tire, the deformation of the tire can be detected. The deformation detection device 1 includes a strain measuring element 11, a signal processing unit 12, and a transmitting unit 13. The signal processing unit 12 further includes a low-speed sampling buffer 121, a high-speed sampling buffer 122, a low-speed sampling average calculation unit 123, a high-speed sampling average calculation unit 124, a feature extraction unit 125, a state determination unit 126, and a deformation calculation unit 127.

[0022] The strain measuring element 11 is an element that detects the strain of an object (e.g., a tire) on which the deformation detection device 1 is installed. The strain measuring element 11 converts the deformation of the strained body into an electrical signal, for example, by utilizing the change in resistance due to the strain. The strain measuring element 11 outputs a measurement signal representing the measurement result to the low-speed sampling buffer 121, the high-speed sampling buffer 122, and the feature extraction unit 125. Which of the low-speed sampling buffer 121 and the high-speed sampling buffer 122 is used will be described later.

[0023] The signal processing unit 12 can switch between a low-speed sampling mode and a high-speed sampling mode. In low-speed sampling mode, the measurement signal is sampled at a lower sampling period, and the frequency of calculating the deformation is also lower than this sampling period. In high-speed sampling mode, the measurement signal is sampled at a higher frequency than in low-speed sampling mode, and the frequency of calculating the deformation is also higher than this sampling period. The sampling period in high-speed sampling mode is, for example, an integer multiple of the sampling period in low-speed sampling mode.

[0024] The low-speed sampling buffer 121 and the high-speed sampling buffer 122 record the measurement signal during a specified period. The low-speed sampling buffer 121 records the measurement signal when operating in low-speed sampling mode. The high-speed sampling buffer 122 records the measurement signal when operating in high-speed sampling mode.

[0025] There are cases where the sampling time in high-speed sampling mode coincides with the sampling time in low-speed sampling mode. In this case, the measurement signal can be recorded in both the low-speed sampling buffer 121 and the high-speed sampling buffer 122. Therefore, the sampling time used as a reference for the state determination unit 126 to determine the motion state of the object (described later) can be either the low-speed sampling period or the high-speed sampling period. The following is based on this operation.

[0026] The low-speed sampling averaging unit 123 calculates the time average of the measurement signal stored in the low-speed sampling buffer 121. The calculation frequency is synchronized with the low-speed sampling period. The high-speed sampling averaging unit 124 calculates the time average of the measurement signal stored in the high-speed sampling buffer 122. The calculation frequency is synchronized with the high-speed sampling period. The low-speed sampling buffer 121 then records the measurement signal at the time when the high-speed sampling period coincides with the low-speed sampling period. Correspondingly, the low-speed sampling averaging unit 123 also calculates the time average of the measurement signal stored in the low-speed sampling buffer 121 at the time when the high-speed sampling period coincides with the low-speed sampling period.

[0027] The feature extraction unit 125 calculates characteristic quantities of the measurement signal by comparing the time average of the measurement signal with the current value of the measurement signal output by the strain measuring element 11. The time average of the measurement signal serves as a judgment criterion. A specific example of the calculation process will be described later.

[0028] The state determination unit 126 determines the motion state of the object based on the feature quantities calculated by the feature extraction unit 125. The motion state referred to here, for example, in the case of detecting tire deformation, is the motion state of the vehicle with the tire installed (e.g., stationary, starting, moving, etc.). The determination criteria will be described later along with examples of the feature quantities.

[0029] The deformation calculation unit 127 uses the measurement signal output by the strain measurement element 11 to calculate the deformation of the object. The time of deformation calculation is synchronized with the time of sampling the measurement signal. That is, the deformation is calculated at a low frequency when sampling at low speed, and at a high frequency when sampling at high speed.

[0030] The transmitting unit 13 transmits the deformation calculated by the deformation calculation unit 127 to the outside of the deformation detection device 1. The time of transmitting the deformation is synchronized with the time of sampling the measurement signal. That is, the deformation is transmitted at a low frequency during low-speed sampling and at a high frequency during high-speed sampling. The transmission method can be either wired or wireless.

[0031] Figure 2 This is a diagram illustrating the state transitions of the signal processing unit 12 in the mode of sampling the measurement signal. Hereinafter, according to... Figure 2 This explains the conditions under which the signal processing unit 12 switches between low-speed sampling mode and high-speed sampling mode. Here, it is assumed that the deformation detection device 1 is installed on the tire of the vehicle.

[0032] ( Figure 2 (Vehicle stopped)

[0033] When the deformation detection device 1 is powered on, the vehicle is assumed to be stationary, therefore there is no need to obtain the tire deformation at a high frequency. Consequently, the signal processing unit 12 samples the measurement signal in a low-speed sampling mode at this time.

[0034] ( Figure 2 (Transfer to the point where the vehicle begins to move)

[0035] When the vehicle starts moving (departs), strain is generated in the tires, and the measurement signal begins to change. The feature extraction unit 125 calculates the difference between the average value of the measurement signal stored in the low-speed sampling buffer 121 and the latest measurement signal output by the strain measurement element 11, as a feature quantity. When the difference exceeds a threshold, the state determination unit 126 determines that the vehicle has started moving (becoming a transitional state between a stopped state and a moving state). For example, when the ratio of the time average value of the measurement signal to the latest value exceeds a threshold, it can be determined that driving has started. When driving begins, the time rate of change of the tire deformation is relatively large, so the signal processing unit 12 samples the measurement signal in a high-speed sampling mode at this time.

[0036] ( Figure 2 Transfer to the point where the vehicle begins to move: (Supplementary explanation)

[0037] If an abnormality is found in the tires when the vehicle departs, actions such as immediately stopping the vehicle can be taken by issuing a warning to the driver indicating this information. This improves vehicle safety. Therefore, it is highly necessary to obtain tire deformation data frequently when the vehicle departs.

[0038] ( Figure 2 (Transition to a state of vehicle in motion)

[0039] When the vehicle departs, the measurement signal generates multiple sharply rising peak waveforms. Before and after these peaks, inverse peak waveforms occur where the measurement signal slightly decreases from a stable state. In the case where the deformation detection device 1 is installed at point 1 on the inner surface of the tire, this peak is caused by strain occurring near the installation point each time the wheel rotates. The feature extraction unit 125 extracts this peak waveform as a feature quantity. When the state determination unit 126 detects this peak waveform more than a predetermined number of times when the vehicle departs, it determines that the vehicle has transitioned to a driving state. In the driving state, the signal processing unit samples the measurement signal in a low-speed sampling mode.

[0040] ( Figure 2 : Transition to a state of vehicle in motion (Supplementary explanation)

[0041] Even while in motion, it is necessary to obtain the amount of tire deformation. However, from the viewpoint of suppressing power consumption, it can be considered that a high-speed sampling mode can be used during departure (starting), when the necessity is higher, and the sampling priority can be reduced while in motion. Therefore, in this embodiment, a low-speed sampling mode is used while in motion.

[0042] ( Figure 2 (Transition to a stationary state)

[0043] The feature extraction unit 125 extracts the aforementioned peak waveform as feature quantities in both the starting and driving states. If the state determination unit 126 does not detect a peak within a specified time, it determines that the vehicle has moved to a stopped state and switches to a low-speed sampling mode.

[0044] ( Figure 2 : Transfer to a stationary vehicle state: supplementary explanation)

[0045] When determining whether a transition has occurred from a starting state to a stopped state, and when determining whether a transition has occurred from a moving state to a stopped state, it is preferable to use the same determination criterion (the measurement signal obtained according to the same criterion). Therefore, when performing these determinations, the feature extraction unit 125 and the state determination unit 126 use the measurement signal stored in the low-speed sampling buffer 121. That is, in the starting state, (a) when determining whether a transition has occurred to a moving state, the measurement signal stored in the high-speed sampling buffer 122 is used, and (b) when determining whether a transition has occurred to a stopped state, the measurement signal stored in the low-speed sampling buffer 121 is used.

[0046] Figure 3 This is a diagram illustrating the time-dependent change of the measurement signal output by the strain measuring element 11. Figure 3 The upper part shows the waveform of the measurement signal sent to the outside by the existing deformation measurement device. Figure 3 The lower part shows the waveform of the measurement signal transmitted (i.e., with the sampling rate adjusted) to the outside of the device by the deformation detection device 1 in this embodiment. Conventionally, measurement signals are acquired at approximately the same frequency and transmitted to the outside of the device regardless of whether the vehicle is in motion, driving, or stationary. This results in high power consumption, making it difficult to ensure the operating time of the deformation measurement device. In this embodiment, the vehicle's operating state is determined as described below, and the sampling mode is changed accordingly. This reduces power consumption.

[0047] When the vehicle transitions from a stopped state to a departure state, the measurement signal increases. The signal processing unit 12 calculates the time average of the measurement signal, and when the difference between this time average and the latest value exceeds a threshold, it determines that the vehicle has transitioned to the departure state. Figure 3 (The state at which the journey has begun). In the state of departure, such as... Figure 3 As shown in the waveform during this period, the measured signal exhibits a large rate of change over time (with multiple rising peaks). Therefore, a high-speed sampling mode is employed during this period.

[0048] When the vehicle is in the departure state, multiple rising peaks in the measurement signal are generated. When this peak reaches a predetermined number of times, it is determined that the vehicle has transitioned to a moving state. In the moving state, a low-speed sampling mode is used. Therefore, in Figure 3 During this period, the frequency of waveform peaks is less than that of the initial state.

[0049] Figure 4 This is an example of the peak waveform of the measurement signal extracted by the feature extraction unit 125 in the starting state. The measurement signal has a slightly decreasing inverse peak before and after the rising peak. When the feature extraction unit 125 detects these three peaks sequentially, it extracts the situation that produced the peak waveform as a feature quantity.

[0050] Specifically, the feature extraction unit 125 performs the following processing: (a) when the difference between the time average value of the measurement signal and the latest value (or the ratio of the latest value to the time average value, the same below) becomes above the upper limit threshold, it is regarded as a rising peak; (b) when the difference between the time average value of the measurement signal and the latest value becomes below the lower limit threshold, it is regarded as a falling peak; (c) when it is continuously generated in the order of falling peak, rising peak and falling peak again, it is determined that a peak waveform has been generated. Figure 4 The measurement signal waveform is accompanied by a record indicating the detection of a rising peak and a falling peak.

[0051] The degree to which a measured signal value is considered stable (with minimal change over time) depends on the operating environment. Therefore, the threshold for peak detection is difficult to define using absolute values. In this embodiment, the measured signal value in a stable state is obtained using time averaging, and peak waveforms are detected based on the degree to which the latest value deviates from this time average. Thus, the aforementioned upper and lower thresholds can be defined, for example, as follows: if the latest value is more than 1.1 times the time average, it is considered a rising peak; if the latest value is less than 0.9 times the time average, it is considered a falling peak. These values ​​are examples.

[0052] The method described above for detecting peak waveforms is the same for both high-speed and low-speed sampled data. Therefore, the calculation result of the high-speed sampling averaging unit 124 is used to determine whether the high-speed sampled data has a peak waveform, and the calculation result of the low-speed sampling averaging unit 123 is used to determine whether the low-speed sampled data has a peak waveform.

[0053] <Implementation Method 1: Summary>

[0054] The deformation detection device 1 of this embodiment 1 determines the vehicle's operating state based on the measurement signal output by the strain measurement element 11. When the vehicle is stationary, the measurement signal is sampled at a low sampling rate, and when the vehicle is in a transitional state from a stationary state to a moving state, the measurement signal is sampled at a high sampling rate. Therefore, the sampling rate is increased only when the necessity of frequently acquiring measurement signals is high, thus suppressing power consumption. Furthermore, because the vehicle's operating state is determined using strain measurement signals, the deformation detection device 1 does not rely on functions other than external sensors or similar devices, and thus it can suppress power consumption itself.

[0055] In the high-speed sampling mode, the deformation detection device 1 of this embodiment 1 stores the measurement signal in the low-speed sampling buffer 121 at the moment when the sampling time coincides with that of the low-speed sampling mode. As a result, for example, the feature extraction unit 125 and the state determination unit 126 can use the same determination criteria (the measurement signal obtained according to the same criteria) when determining whether the driving start state has transitioned to the stop state and when determining whether the driving state has transitioned to the stop state.

[0056] The deformation detection device 1 of this embodiment 1 uses a low sampling rate while in motion. This allows for accurate determination of tire abnormalities at the start of travel using a high sampling rate, while also suppressing power consumption.

[0057] <Implementation Method 2>

[0058] In Embodiment 1, it is explained that during the period when the state determination unit 126 determines that the vehicle has started driving, at the moment when the peak waveform of the measurement signal is detected a predetermined number of times, it is determined that the vehicle has transitioned to a driving state. For example, Figure 3 The example shown illustrates the transition to the driving state when 10 peak waveforms are detected during the initial driving period. Alternatively, instead of detecting a predetermined number of peak waveforms, the transition to the driving state can be determined based on the continuous appearance of peak waveforms for a predetermined period of time.

[0059] The state determination unit 126 can perform the determination as follows: If, during the initial driving state, the period without a peak waveform exceeds a predetermined time, it is determined that the system has transitioned to a stopped state. If this is not the case, the peak waveform is considered continuous. In other words, if the period without a peak waveform does not exceed the predetermined time, it is determined that the system has transitioned to a driving state. This is equivalent to detecting that the tire has been continuously rotating for a certain period of time.

[0060] <Regarding variations of the present invention>

[0061] This invention is not limited to the embodiments described above, and includes various modifications. For example, the embodiments described above are detailed for ease of understanding and explanation of the invention, and are not limited to having all the structures described. Furthermore, a portion of the structure of one embodiment can be replaced with the structure of another embodiment, and structures of other embodiments can be added to the structure of one embodiment. Additionally, for a portion of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0062] In the above embodiments, the sampling rate in the stationary state and the sampling rate in the moving state can also be different. For example, a low sampling rate can be used in the stationary state, a medium sampling rate (the intermediate sampling rate between low-speed and high-speed sampling) can be used in the moving state, and a high sampling rate can be used in the starting state of movement. In this case, the sampling buffer and the averaging unit can also be newly set respectively corresponding to the medium sampling rate.

[0063] In the above embodiments, the signal processing unit 12 and its functions can be configured not only by hardware such as circuit devices that implement their functions, but also by software that implements their functions by executing a computing device such as a processor.

[0064] The above embodiments illustrate an example of mounting the deformation detection device 1 on a tire to detect the tire's strain. However, the present invention can also be applied to detect the strain of objects other than tires. That is, the present invention is useful in situations where the deformation detection device 1 determines the motion state of the object on which it is mounted and adjusts the sampling frequency accordingly.

[0065] Explanation of reference numerals in the attached figures

[0066] 1: Deformation detection device

[0067] 11: Strain measurement element

[0068] 12: Signal Processing Department

[0069] 121: Low-speed sampling buffer

[0070] 122: High-speed sampling buffer

[0071] 123: Low-speed sampling average calculation unit

[0072] 124: High-speed sampling average calculation unit

[0073] 125: Feature Extraction Department

[0074] 126: Status Judgment Department

[0075] 127: Deformation Calculation Department

[0076] 13: Sending Department.

Claims

1. A deformation detection device, which is mounted on an object to detect the deformation of the object, characterized in that it comprises: A strain measuring element that measures the deformation and outputs a measurement signal representing the measurement result; A signal processing unit that processes the measured signals; and A transmitting unit that transmits the processing results of the signal processing unit; The signal processing unit includes: A feature extraction unit extracts the time-varying characteristic quantities of the measured signal; A state determination unit that determines the motion state of the object based on the aforementioned feature quantities; and The deformation calculation unit uses the measured signal to calculate the deformation amount. During the period when the state determination unit determines that the object is in a stopped state, the deformation calculation unit acquires the measurement signal at a first sampling rate and calculates the deformation. During the period when the state determination unit determines that the object is in a transitional state from the stopped state to the moving state, the deformation calculation unit acquires the measurement signal at a second sampling rate with a frequency higher than the first sampling rate and calculates the deformation amount. During the period when the state determination unit determines that the object is in the stopped state, the feature extraction unit extracts the first time-varying change, which is the difference between the average value of the measurement signal over a predetermined time and the latest value, and which is above a first threshold, as the feature quantity. During the period when the state determination unit determines that the object is in the transition state, the feature extraction unit extracts the second time-varying change of the latest value of the measurement signal from being above a second threshold to being below a third threshold that is below the second threshold as the feature quantity. When the state determination unit determines that the object is in the stopped state, and the feature extraction unit extracts the first time-varying change, it determines that the object has transitioned to the transition state. When the state determination unit determines that the object is in the transition state, and the feature extraction unit continuously extracts the second time change a predetermined number of times or continuously extracts the second time change over a predetermined period of time, the state determination unit determines that the object has transitioned to the moving state.

2. The deformation detection device as described in claim 1, characterized in that: The signal processing unit further includes: A first sampling buffer stores the measurement signal at each of the first sampling rates; and A second sampling buffer stores the measurement signal at each of the second sampling rates; During the period when the deformation calculation unit acquires the measurement signal at the second sampling rate, the first sampling buffer saves the measurement signal at a time when the sampling time of the second sampling rate coincides with the sampling time of the first sampling rate.

3. The deformation detection device as described in claim 1, characterized in that: The signal processing unit further includes: A first sample averaging unit that calculates the average value of the measured signal for each of the first sampling rates; and The second sample averaging unit calculates the average value of the measured signal for each of the second sampling rates; The first sample average calculation unit calculates the average value of the measurement signal at a time when the deformation calculation unit acquires the measurement signal at the second sampling rate, and at a time when the sampling time at the second sampling rate coincides with the sampling time at the first sampling rate. The feature extraction unit uses the average value of the measurement signal to extract the feature quantity.

4. The deformation detection device as described in claim 1, characterized in that: During the period when the state determination unit determines that the object is in the moving state or the transition state, the feature extraction unit extracts the second time-varying change as the feature quantity. The state determination unit determines that the object is in the stopped state when the deformation detection device is powered on, or when the feature extraction unit fails to extract the second time change within a specified time in the transition state, or when the feature extraction unit fails to extract the second time change within a specified time in the moving state.

5. A deformation detection device, which is mounted on an object to detect the deformation of the object, characterized in that it comprises: A strain measuring element that measures the deformation and outputs a measurement signal representing the measurement result; A signal processing unit that processes the measured signals; and A transmitting unit that transmits the processing results of the signal processing unit; The signal processing unit includes: A feature extraction unit extracts the time-varying characteristic quantities of the measured signal; A state determination unit that determines the motion state of the object based on the aforementioned feature quantities; and The deformation calculation unit uses the measured signal to calculate the deformation amount. During the period when the state determination unit determines that the object is in a stopped state, the deformation calculation unit acquires the measurement signal at a first sampling rate and calculates the deformation. During the period when the state determination unit determines that the object is in a transitional state from the stopped state to the moving state, the deformation calculation unit acquires the measurement signal at a second sampling rate with a frequency higher than the first sampling rate and calculates the deformation amount. The signal processing unit further includes: A first sampling buffer stores the measurement signal at each of the first sampling rates; and The second sampling buffer stores the measurement signal at each of the second sampling rates. During the period when the state determination unit determines that the object is in the moving state, the feature extraction unit uses the measurement signal stored in the first sampling buffer to extract the feature quantity. During the period when the state determination unit determines that the object is in the transition state, the feature extraction unit uses the measurement signal stored in the first sampling buffer to extract the feature quantity, and also uses the measurement signal stored in the second sampling buffer to extract the feature quantity. When determining whether the object has transitioned from the transition state to the stopped state, the state determination unit uses the feature quantity extracted using the measurement signal stored in the first sampling buffer. When determining whether the object has transitioned from the moving state to the stopped state, the state determination unit uses the feature quantity extracted using the measurement signal stored in the first sampling buffer. When determining whether the object has transitioned from the transition state to the moving state, the state determination unit uses the feature quantity extracted using the measurement signal stored in the second sampling buffer.

6. The deformation detection device as described in claim 5, characterized in that: During the period when the deformation calculation unit acquires the measurement signal at the second sampling rate, the first sampling buffer saves the measurement signal at a time when the sampling time of the second sampling rate coincides with the sampling time of the first sampling rate.

7. The deformation detection device as described in claim 5, characterized in that: The signal processing unit further includes: A first sample averaging unit that calculates the average value of the measured signal for each of the first sampling rates; and The second sample averaging unit calculates the average value of the measured signal for each of the second sampling rates; The first sample average calculation unit calculates the average value of the measurement signal at a time when the deformation calculation unit acquires the measurement signal at the second sampling rate, and at a time when the sampling time at the second sampling rate coincides with the sampling time at the first sampling rate. The feature extraction unit uses the average value of the measurement signal to extract the feature quantity.

8. The deformation detection device according to any one of claims 1 to 7, characterized in that: During the period when the state determination unit determines that the object is in the moving state, the deformation calculation unit acquires the measurement signal at a third sampling rate with a frequency higher than the first sampling rate and lower than the second sampling rate and calculates the deformation.

9. The deformation detection device according to any one of claims 1 to 7, characterized in that: The object is the tire of a vehicle equipped with the deformation detection device. The stopped state is the state in which the tires also stop because the vehicle has stopped. The "moving state" refers to the state in which the vehicle is in motion.

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