Impact detection device and impact detection method

Abstract

To provide an impact detection device and an impact detection method capable of accurately detecting an impact applied to a vehicle.SOLUTION: An impact detection device comprises: a storage part for storing acceleration occurring on a vehicle in association with lapse of time; and a determination part for determining whether or not an impact is given to the vehicle at each timing in a prescribed time period on the basis of a change rate of the acceleration during the prescribed time period.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to an impact detection device and an impact detection method for detecting an impact applied to a vehicle. [Background technology]

[0002] A device for detecting an act of harm against a vehicle is disclosed in, for example, Patent Document 1. Patent Document 1 discloses an act of harm detection device that can detect the occurrence of a hit-and-run and identify the offending vehicle when a hit-and-run occurs against the vehicle itself. The act of harm detection device of Patent Document 1 detects the occurrence of a hit-and-run and identifies the offending vehicle by detecting an impact using an impact detection means and photographing and recording the image in the direction of the impact using a camera. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-302017 A Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the impact detection means detects an impact based on a change in deceleration (acceleration) applied to the vehicle. However, because deceleration may be applied to the vehicle in cases other than when an impact is applied to the vehicle, the technology disclosed in Patent Document 1 may cause erroneous detection. Specifically, if a strong wind blows against the vehicle or the vehicle is shaken when parked in a mechanical parking lot, the impact detection means may make a erroneous detection.

[0005] The present disclosure contributes to providing an impact detection device and an impact detection method that can accurately detect an impact applied to a vehicle. [Means for solving the problem]

[0006] An impact detection device according to one embodiment of the present disclosure includes a memory circuit that stores acceleration applied to a vehicle in association with the passage of time, and a determination circuit that determines whether an impact has been applied to the vehicle at each timing during a specified period based on a rate of change of the acceleration during the specified period.

[0007] An impact detection device according to one embodiment of the present disclosure includes a memory circuit that stores a vehicle's speed and acceleration, each associated with the passage of time, and a judgment circuit that judges whether an impact has been applied to the vehicle at a first timing based on whether the acceleration at the first timing is greater than or equal to a predetermined acceleration threshold, and the judgment circuit changes the acceleration threshold based on the speed at a second timing that is a predetermined time after the first timing.

[0008] An impact detection method according to one aspect of the present disclosure stores acceleration applied to a vehicle in association with the passage of time, and determines whether an impact has been applied to the vehicle at each timing during a specified period based on the rate of change of the acceleration during the specified period.

[0009] An impact detection method according to one embodiment of the present disclosure stores a vehicle's speed in association with the passage of time, and determines whether or not an impact has been applied to the vehicle at a first timing based on whether the acceleration at the first timing is greater than or equal to a predetermined acceleration threshold, and in determining whether or not an impact has been applied to the vehicle, changes the acceleration threshold based on the speed at a second timing that is a predetermined time after the first timing. Effect of the Invention

[0010] According to the present disclosure, an impact applied to a vehicle can be detected with high accuracy. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an example of a configuration of an impact detection system according to a first and second embodiment of the present disclosure; [Diagram 2]FIG. 1 is a block diagram showing an example of a functional configuration of an impact detection device according to a first embodiment; [Diagram 3] 1 is a flowchart of a determination process performed by a determination unit according to a first embodiment. [Figure 4] FIG. 1 shows an example of acceleration occurring in a vehicle. [Diagram 5] FIG. 1 is a diagram showing the relationship between the acceleration, jerk, and impact value of a vehicle when an impact is applied to the vehicle, when the vehicle is shaking due to being parked in a mechanical parking lot, and when the vehicle is shaking due to wind. [Figure 6] A flowchart for explaining an example of the overall operation of the impact detection device. [Figure 7] FIG. 13 is a diagram showing the relationship between the jerk and the acceleration when a predetermined value for distinguishing between the detection timing and other times is set to a constant value and when the predetermined value is changed; [Figure 8] FIG. 11 is a block diagram showing an example of a functional configuration of an impact detection device according to a second embodiment. [Figure 9] 13A and 13B are diagrams showing examples of acceleration before and after filtering and speeds calculated by a speed calculation unit when an impact is applied to a vehicle V and when the vehicle V is parked in a mechanical parking lot. [Figure 10] FIG. 11 is a diagram for explaining calculation of a velocity by a velocity calculation unit according to a second embodiment; [Figure 11] 11 is a flowchart of a determination process performed by a determination unit according to a second embodiment. [Figure 12] FIG. 13 is a diagram for explaining a relationship between a first timing and a second timing in the second embodiment. [Figure 13] 11 is a flowchart for explaining an example of the overall operation of the impact detection device according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. However, more detailed explanation than necessary, for example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration, may be omitted.

[0013] <Summary> 1 is a diagram showing an example of the configuration of an impact detection system 100 according to the first and second embodiments of the present disclosure. The impact detection system 100 includes an acceleration sensor 10 installed inside a vehicle V, and impact detection devices 20 and 30. The impact detection device 20 corresponds to the first embodiment, and the impact detection device 30 corresponds to the second embodiment.

[0014] 1, the impact detection devices 20, 30 are installed outside the vehicle V, and the acceleration sensor 10 and the impact detection devices 20, 30 are connected to each other via wire or wirelessly so that they can communicate with each other. The impact detection device 20 is, for example, a computer equipped with a processor, a storage device, an input means, etc. Note that the present disclosure is not limited to an embodiment in which the impact detection devices 20, 30 are installed outside the vehicle V, and in the present disclosure, the impact detection devices 20, 30 may be installed inside the vehicle V.

[0015] The acceleration sensor 10 detects the acceleration occurring in the vehicle V. The acceleration sensor 10 detects the acceleration occurring in the vehicle V per unit time, and outputs to the impact detection devices 20, 30 acceleration information indicating the magnitude of the detected acceleration.

[0016] The impact detection devices 20, 30 detect that an impact has been applied to the vehicle V based on the acceleration information input from the acceleration sensor 10. In this specification, an impact refers to a phenomenon in which a large acceleration occurs instantaneously in the vehicle due to an object colliding with the vehicle V or vandalism occurring. Examples of objects that collide with the vehicle V when an impact occurs include people, bicycles, other vehicles, etc.

[0017] In addition to when an impact is applied to the vehicle V, the acceleration sensor 10 may detect the acceleration occurring in the vehicle V. For example, when the vehicle V is shaken by wind, an earthquake, or the like, the acceleration sensor 10 may detect the acceleration occurring in the vehicle V. Also, when the vehicle V is parked in a place where the parking space itself moves, such as a mechanical parking lot, the acceleration sensor 10 may detect the acceleration occurring in the vehicle V.

[0018] In this specification, a mechanical parking lot refers to a parking lot where a pallet for parking a vehicle moves while the vehicle is parked. Mechanical parking lots in this specification include two-level aboveground parking lots, two-level pit parking lots (devices with an underground structure), lift-and-transport parking lots, vertical circulation parking lots, and elevator parking lots (classified by the Multi-storey Parking Industry Association). In the following embodiments, a vertical circulation parking lot, for example, a so-called tower parking lot, is assumed as the mechanical parking lot.

[0019] The present disclosure provides an impact detection device 20, 30 that can suppress erroneous detection of an impact being applied to the vehicle V when acceleration of the vehicle V occurs due to wind, an earthquake, or movement in a parking space, and can accurately detect that an impact has been applied to the vehicle V.

[0020] First Embodiment The impact detection device 20 according to the first embodiment of the present disclosure will be described below. Fig. 2 is a block diagram showing an example of a functional configuration of the impact detection device 20 according to the first embodiment.

[0021] The impact detection device 20 includes an acquisition unit 21, a storage unit 22, a rate of change calculation unit 23, and a determination unit 24.

[0022] The acquisition unit 21 acquires acceleration information from the acceleration sensor 10 shown in Fig. 1. The acquisition unit 21 may further acquire information other than the acceleration information from a configuration other than the acceleration sensor 10. For example, the acquisition unit 21 may acquire speed information of the vehicle V from a speed sensor installed inside the vehicle V.

[0023] The storage unit 22 stores the acceleration generated in the vehicle V in association with the passage of time. The storage unit 22 stores, for example, acceleration information acquired from the acceleration sensor 10 for each unit time and the time at which the acceleration information was generated (or the time at which the acceleration information was acquired) in association with each other. The unit time is not limited in this disclosure, but the unit time may be set to, for example, one second.

[0024] The change rate calculation unit 23 calculates the rate of change of the acceleration per unit time based on the information related to the acceleration and the passage of time stored in the storage unit 22.

[0025] The change rate calculation unit 23 calculates the change rate using, for example, the following formula (1). |J[n]|=|a impact [n]-a impact [n-1] | (1) n indicates the number of samples among the samples of acceleration information stored in the storage unit 22 sampled per unit time. n is an integer value. J[n] indicates the rate of change of acceleration in the nth sample. impact [n] is the impulse value at the nth sample, and a impact [n-1] is the shock value for the (n-1)th sample. The shock value is calculated by subtracting the gravitational acceleration from the acceleration for that sample.

[0026] J[n] calculated by the change rate calculation unit 23 is the rate of change of acceleration per unit time, for example, a jerk. In the above example, the change rate calculation unit 23 calculates the jerk based on the difference in acceleration (impact value) between adjacent samples when sampling is performed every unit time, but the present disclosure is not limited to this, and for example, the change rate calculation unit 23 may calculate the jerk by differentiating the rate of change of acceleration with respect to time without performing sampling.

[0027] The determination unit 24 determines whether or not an impact has been applied to the vehicle V based on the rate of change of acceleration (jerk) at each timing included in the predetermined period. The predetermined period is a timing that is subject to detection by the impact detection device 20. The predetermined period is a period that is arbitrarily set in the determination process of the determination unit 24, and is, for example, a period from the present to several seconds or several tens of seconds ago.

[0028] Specifically, the determination unit 24 determines whether or not an impact has been applied to the vehicle V in the following procedure. FIG.

[0029] First, in step S1, the determination unit 24 acquires information related to the acceleration occurring in the vehicle V during a predetermined period of time, and information related to the jerk during the predetermined period of time calculated by the change rate calculation unit 23 based on the acceleration.

[0030] Next, in step S2, the determination unit 24 identifies the timing at which the jerk is equal to or greater than a predetermined threshold value during a predetermined period. Hereinafter, the timing at which the jerk is equal to or greater than a predetermined value will be referred to as the detection timing. The predetermined value is a preset threshold value for the jerk. A method for setting the predetermined value will be described later.

[0031] Next, in step S3, the determination unit 24 sets a predetermined threshold value for determining whether or not an impact has been applied to the vehicle during a predetermined period. The predetermined threshold value is a threshold value for comparing with a preset acceleration value to determine whether or not an impact has been applied. Hereinafter, the threshold value for comparison with the acceleration value used in step S3 is referred to as an acceleration threshold value. The acceleration threshold value is set to a different value for the detection timing and other timings.

[0032] Specifically, the determination unit 24 sets the acceleration threshold to a first value at a timing during a predetermined period when the rate of change in acceleration (jerk) is less than a predetermined value, for example, at a timing other than the detection timing, while the determination unit 24 sets the acceleration threshold to a second value smaller than the first value at a detection timing when the rate of change in acceleration is equal to or greater than the predetermined value.

[0033] In step S4, the determination unit 24 uses the threshold value set in step S3 and information related to the acceleration during the predetermined period to determine whether or not an impact has been applied to the vehicle V. Specifically, when the acceleration exceeds the threshold value at each timing during the predetermined period, the determination unit 24 determines that an impact has been applied to the vehicle V at that timing.

[0034] By adopting such a judgment method, the judgment unit 24 can accurately detect whether or not an impact has been applied to the vehicle V, and can suppress erroneous detection that an impact has been applied to the vehicle V when acceleration of the vehicle V occurs due to, for example, wind, an earthquake, or movement in a parking space.

[0035] The effect of the impact determination method by the determination unit 24 will be described below with a specific example.

[0036] Fig. 4 is a diagram showing an example of acceleration occurring in vehicle V. Fig. 4A is a graph showing examples of acceleration when an impact is applied to vehicle V, when vehicle V is shaking due to being parked in a mechanical parking lot, and when vehicle V is shaking due to wind. In Fig. 4A, the circled parts are the timings at which fluctuations in acceleration occur, for example, when vehicle V is applied with an impact, or when vehicle V is shaking due to the movement of a parking pallet or wind. Fig. 4B is a graph in which a part (circled part) of Fig. 4A is enlarged in the time direction.

[0037] 4A and 4B, the amount of acceleration fluctuation when an impact is applied to the vehicle V is smaller than the amount of acceleration fluctuation when the vehicle V is shaking due to being parked in a mechanical parking lot and when the vehicle V is shaking due to wind. For example, in the example shown in Fig. 4A and 4B, it is difficult to accurately determine whether or not an impact has been applied to the vehicle V based on the amount of acceleration fluctuation.

[0038] 4B, it is clear that the acceleration changes more abruptly, for example the rate of change in acceleration is greater, when the vehicle V is subjected to an impact than when the vehicle V is swaying due to being parked in a mechanical parking lot or when the vehicle V is swaying due to wind. This is because swaying due to being parked in a mechanical parking lot or swaying due to wind is the motion of the entire vehicle and is influenced by inertia (mass) and the size of the vehicle and is unlikely to result in a sudden change in acceleration, whereas an impact is a force acting on a part of the vehicle and the instantaneous deformation of the vehicle is expressed as acceleration.

[0039] For this reason, the judgment unit 24 judges whether or not an impact has occurred based on the rate of change in acceleration in each of the following cases: when an impact has been applied to the vehicle V, when the vehicle V is shaking due to being parked in a mechanical parking lot, and when the vehicle V is shaking due to wind.

[0040] FIG. 5 is a diagram showing the relationship between the acceleration, jerk, and impact value that occurs in vehicle V when an impact is applied to vehicle V, when vehicle V is shaking due to being parked in a mechanical parking lot, and when vehicle V is shaking due to wind.

[0041] On the left side of Figure 5, there is shown in the upper part a graph showing the acceleration that occurs in the vehicle V when an impact is applied to the vehicle V, in the middle part a graph showing the jerk calculated based on the acceleration, and in the lower part a graph showing an impact value calculated by subtracting the gravitational acceleration from the acceleration that occurs in the vehicle V.

[0042] In the center of Figure 5, there is shown a graph at the top showing the acceleration that occurs to vehicle V when shaking occurs due to vehicle V being parked in a mechanical parking lot, a graph at the middle showing the jerk calculated based on the acceleration, and a graph at the bottom showing the impact value calculated by subtracting the acceleration of gravity from the acceleration that occurs to vehicle V.

[0043] On the right side of Figure 5, the upper part shows a graph showing the acceleration that occurs to the vehicle V when the vehicle V is swaying due to wind, the middle part shows a graph showing the jerk calculated based on the acceleration, and the lower part shows a graph showing an impact value calculated by subtracting the acceleration of gravity from the acceleration that occurs to the vehicle V.

[0044] It should be noted that the upper graph in FIG. 5 (graph showing the acceleration occurring in the vehicle V in each case) is the same as that shown in FIG. 4A.

[0045] Referring to the graph showing the jerk in each case shown in the middle of Fig. 5, the jerk when an impact is applied to the vehicle V is generally larger than the other cases. This is because, as described in relation to Fig. 4, generally, a steeper fluctuation in acceleration occurs, for example, the jerk is larger, when the vehicle V is subjected to an impact than when the vehicle V is swaying due to being parked in a mechanical parking lot or when the vehicle V is swaying due to wind.

[0046] Here, the predetermined value, which is the threshold value of the jerk, used in the process of step S2 in Fig. 3 may be set to a constant value (see "predetermined value" shown in Fig. 5) that is smaller than the peak of the jerk when an impact is applied to the vehicle V and is larger than the peak of the jerk when the vehicle V is shaking due to being parked in a mechanical parking lot or when the vehicle V is shaking due to wind. This enables the determination unit 24 to accurately determine, through the process of step S2 in Fig. 3, the detection timing at which it is highly likely that the acceleration has changed due to an impact being applied to the vehicle V and the timing at which it is highly likely that the acceleration has changed due to the movement of the parking pallet or the shaking of the vehicle V due to wind.

[0047] The graph showing the impact values ​​in each case shown in the lower part of Fig. 5 illustrates the acceleration threshold value set by the process of step S3 in Fig. 3. In the graph in the lower part of Fig. 5, a first value, which is a threshold value at a timing other than the detection timing, is shown by a solid line, and a second value, which is a threshold value at the detection timing, is shown by a dashed line. The first value may be determined in advance by experiments, etc., to be, for example, a value slightly larger than the maximum value of the acceleration (impact value) generated in the vehicle V due to a mechanical parking lot or shaking caused by wind. The second value may be determined in advance by experiments, etc., to be, for example, a value slightly smaller than the maximum value of the acceleration (impact value) generated in the vehicle V when an impact is actually applied to the vehicle V.

[0048] FIG. 6 is a flowchart for explaining an example of the overall operation of the impact detection device 20. As shown in FIG.

[0049] In step S11, the acquisition unit 21 acquires information about acceleration from the acceleration sensor 10 of the vehicle V.

[0050] In step S12, the storage unit 22 stores information regarding the acceleration and the passage of time during a predetermined period.

[0051] In step S13, the change rate calculation unit 23 calculates the jerk at each timing in a predetermined period based on the information stored in the storage unit 22.

[0052] In step S14, the determination unit 24 determines whether or not an impact has been applied to the vehicle V, based on the jerk at each timing.

[0053] As described above, according to the impact detection device 20 according to the first embodiment of the present disclosure, it is possible to accurately determine whether an impact has been applied to the vehicle V, whether the vehicle V is shaking due to being parked in a mechanical parking lot, or whether the vehicle V is shaking due to wind, based on the jerk at each timing during a predetermined period. This makes it possible to determine in advance whether or not an impact is likely to have been applied to the vehicle V at each timing. Then, based on the result of the determination, the acceleration threshold for determining the presence or absence of an impact using the acceleration (impact value) is changed depending on the timing at which an impact is likely to have been applied to the vehicle V and the other timing, and the presence or absence of an impact is determined by comparing the acceleration with the acceleration threshold at each timing, so that it is possible to accurately detect that an impact has been applied to the vehicle V.

[0054] <Modification> A modification of the first embodiment will now be described.

[0055] In the first embodiment, the judgment unit 24 distinguishes between detection timings at which it is highly likely that an impact has been applied to the vehicle V and timings at which it is not, based on information regarding jerk over a specified period of time, and accurately detects an impact applied to the vehicle V by changing the acceleration threshold value for determining whether or not an impact due to acceleration has been applied between the detection timing and timings other than the detection timing.

[0056] In the present disclosure, instead of changing the acceleration threshold value for determining based on acceleration between the detection timing and timing other than the detection timing, it may be determined that an impact has been applied to the vehicle, for example, simply at a timing when the jerk is equal to or greater than a predetermined value within a predetermined period of time.

[0057] In this case, the determination unit can determine whether an impact has been applied to the vehicle by determining whether the jerk is equal to or greater than a predetermined value at each timing in a predetermined period, which simplifies the processing, and therefore the calculation resources of the impact detection device can be reduced, making it possible to provide the impact detection device at a low cost.

[0058] In the first embodiment, the determination unit 24 sets a predetermined value for distinguishing between detection timings at which it is highly likely that an impact has been applied to the vehicle V and timings at which it is not likely that an impact has been applied to the vehicle V to a constant value that has been set in advance. Here, the predetermined value may be changed based on the magnitude of acceleration at each timing, for example. This makes it possible to accurately distinguish between a jerk caused by an impact applied to the vehicle V and a jerk caused by other factors, such as noise.

[0059] Fig. 7 is a diagram showing the relationship between the jerk and acceleration when a predetermined value for distinguishing between detection timing and other times is fixed and when it is varied. Fig. 7A shows the relationship between the jerk and acceleration when the predetermined value is fixed, and Fig. 7B shows the relationship when the predetermined value is varied based on the acceleration.

[0060] 7A and 7B, ■ (black square) indicates data due to an impact given to vehicle V, and ● (black circle) indicates data generated by noise. Also, in Fig. 7A and 7B, data with a jerk smaller than a predetermined value corresponds to a timing equal to or smaller than the predetermined value in the graph in the middle of Fig. 5, and in the process of determining whether or not there is an impact in step S4 of Fig. 3, this data is considered to be a timing other than the detection timing, and is subjected to a determination using the larger first threshold value.

[0061] 7A and 7B, in the region where the acceleration is small, the jerk is also small, and data due to impact and data caused by noise are mixed. Therefore, if the predetermined value is set to a constant value, as shown in FIG. 7A, in the data in the region where the acceleration is small, data due to impact other than data caused by noise may have a jerk less than the predetermined value, and may be erroneously determined to be a timing other than the detection timing.

[0062] On the other hand, in Fig. 7B, the predetermined value is changed linearly so that the greater the acceleration, the greater the predetermined value becomes. By setting the predetermined value in this manner, it is possible to prevent a situation in which data due to an impact is erroneously determined to be a timing other than the detection timing in a region where the jerk is small, as shown in Fig. 7B.

[0063] <Second embodiment> The impact detector 30 according to the second embodiment of the present disclosure will be described below. Fig. 8 is a block diagram showing an example of the functional configuration of the impact detector 30 according to the second embodiment.

[0064] The impact detection device 30 includes an acquisition unit 31, a storage unit 32, a speed calculation unit 33, and a determination unit .

[0065] The acquisition unit 31 acquires acceleration information from the acceleration sensor 10 shown in Fig. 1. The acquisition unit 31 may further acquire information other than the acceleration information from a configuration other than the acceleration sensor 10. For example, the acquisition unit 31 may acquire speed information of the vehicle V from a speed sensor installed inside the vehicle V.

[0066] The storage unit 32 stores the acceleration generated in the vehicle V in association with the passage of time. The storage unit 32 stores, for example, acceleration information acquired from the acceleration sensor 10 per unit time and the time at which the acceleration information was generated (or the time at which the acceleration information was acquired) in association with each other.

[0067] The speed calculation unit 33 calculates the speed of the vehicle V at each timing during a predetermined period based on the information regarding the acceleration and the passage of time stored in the memory unit 32.

[0068] The speed calculation unit 33 first filters the information regarding acceleration over a specified period of time using a specified filter such as a low-pass filter, thereby removing components due to the impact applied to the vehicle V and components due to noise from the information regarding acceleration.

[0069] The type of low-pass filter used by the speed calculation unit 33 is not limited, but for example, a filter represented by the following formula (2) may be used.

number

[0070] Then, the speed calculation unit 33 calculates the speed at each timing within the predetermined period using the information on the acceleration after filtering. Specifically, the speed calculation unit 33 calculates the speed of the vehicle V at a certain timing T1 within the predetermined period by integrating the acceleration from a timing T0 before T1 to the timing T1. Note that the length of the interval over which the speed is integrated to calculate the acceleration, for example, the length of the time between the timings T0 and T1, may be set to any value in advance.

[0071] The speed calculation unit 33 uses the acceleration after filtering to calculate the speed of the vehicle V at the time T1, for example, by the following equation (3).

number

[0072] FIG. 9 is a diagram showing an example of acceleration before and after filtering and a speed calculated by the speed calculation unit 33 in each of a case where an impact is applied to the vehicle V and a case where the vehicle V is parked in a mechanical parking lot. The left side of FIG. 9 shows a graph in a case where an impact is applied to the vehicle V, and the right side of FIG. 9 shows a graph in a case where the vehicle V is parked in a mechanical parking lot. In addition, the upper part of FIG. 9 shows a graph showing the acceleration before filtering, and the middle part of FIG. 9 shows a graph showing the acceleration after filtering. The lower part of FIG. 9 shows a graph showing the speed calculated by the speed calculation unit 33 based on the acceleration after filtering.

[0073] As described above, the low-pass filter used by the speed calculation unit 33 removes the acceleration components and noise components due to the impact, so that after filtering, the acceleration when an impact is applied to the vehicle V is approximately 0, as shown in Fig. 9. As a result, the speed of the vehicle V calculated by the speed calculation unit 33 becomes approximately 0 when an impact is applied to the vehicle V.

[0074] FIG. 10 is a diagram for explaining the calculation of the velocity by the velocity calculation unit 33. The upper part of FIG. 10 is a graph for explaining a section in which the velocity calculation unit 33 calculates the velocity from the acceleration. In the upper part of FIG. 10, the acceleration from timing T0 to T1 is used to calculate the velocity at timing T1. Moreover, the acceleration from timing T2 to T3 is used to calculate the velocity at timing T3. Moreover, the acceleration from timing T4 to T5 is used to calculate the velocity at timing T5. In this way, the velocity calculation unit 33 integrates the acceleration of an arbitrary section ending at a specific timing in order to calculate the velocity at a specific timing within a predetermined period.

[0075] The lower part of Fig. 10 is a graph showing the relationship between the speed calculated by the speed calculation unit 33 and the passage of time. The lower part of Fig. 10 shows the speed at timing T1, the speed at timing T3, and the speed at timing T5.

[0076] By using such a speed calculation method, the effects of background noise and quantization error can be suppressed, and the speed can be calculated with high accuracy.

[0077] In the present disclosure, the speed calculation unit may not be limited to the calculation method of calculating the speed by integrating the acceleration. For example, information on the speed acquired from a speed sensor mounted on the vehicle may be used. In addition, when acquiring the speed of the vehicle from the speed sensor, if the speed component due to the impact given to the vehicle is difficult to measure by the speed sensor, filtering may not be performed.

[0078] The determination unit 34 determines whether or not an impact has been applied to the vehicle V at a first timing in a predetermined period, based on the speed at a second timing a predetermined time after the first timing. The first timing is a timing that is a target of determination by the determination unit 34 within the predetermined period.

[0079] Specifically, the determination unit 34 determines whether or not an impact has been applied to the vehicle V in the following procedure. FIG. 11 is a flowchart of the determination process performed by the determination unit 34.

[0080] First, in step S21, the determination unit 34 acquires information about the speed of the vehicle V at each timing during a predetermined period.

[0081] Next, in step S22, the determination unit 34 determines whether or not the speed at a second timing a predetermined time after the first timing to be determined within the predetermined period is equal to or greater than a predetermined speed threshold.

[0082] The determination unit 34 executes the determination process sequentially at each timing of a predetermined period. The first timing is a timing that is a target of the determination process.

[0083] The speed threshold is a threshold used to determine whether the first timing is likely to be the timing at which the vehicle V was subjected to an impact.

[0084] Fig. 12 is a diagram for explaining the relationship between the first timing and the second timing. The graph on the left side of Fig. 12 shows an example of a speed change when an impact is applied to the vehicle V, and the graph on the right side shows an example of a speed change when the vehicle V is parked in a mechanical parking lot.

[0085] Since the vehicle V has a relatively large mass, when acceleration occurs in the vehicle V, it takes a certain amount of time for the vehicle V to start moving due to the acceleration, for example, for the speed of the vehicle V to become greater than 0.

[0086] For this reason, the determination unit 34 uses the speed at a second timing, which is a predetermined time after the first timing, to determine whether or not the first timing is a timing at which it is highly likely that an impact was applied to the vehicle V. The acceleration that occurs in the vehicle when an impact is applied to the vehicle V is steeper than when no impact is applied. For example, when an impact is applied to the vehicle V at the first timing, the speed of the vehicle at the second timing after the predetermined time has elapsed is not affected by the impact applied at the first timing and is considered to be close to 0.

[0087] For example, by setting the speed threshold to a value close to 0, if the speed at the second timing is less than the speed threshold, the first timing can be identified as a timing at which it is highly likely that an impact was applied to the vehicle V (see the graph on the left side of FIG. 12). On the other hand, if the speed at the second timing is equal to or greater than the speed threshold, the first timing can be determined as a timing at which it is highly likely that the speed of the vehicle V is caused by a cause other than an impact (see the graph on the right side of FIG. 12).

[0088] Next, in step S23, the judgment unit 34 changes the acceleration threshold value for comparison with the acceleration at the first timing based on the judgment result in step S22 in order to determine whether or not an impact was applied to the vehicle V at the first timing.

[0089] Specifically, when the speed at the second timing is equal to or greater than the speed threshold, the determination unit 34 sets the acceleration threshold to a relatively large first value because the possibility that an impact was applied to the vehicle V at the first timing is relatively low (see the graph on the right side of FIG. 12). On the other hand, when the speed at the second timing is less than the speed threshold, the determination unit 34 sets the acceleration threshold to a second value smaller than the first value because the possibility that an impact was applied to the vehicle V at the first timing is relatively high (see the graph on the left side of FIG. 12).

[0090] In step S24, the determination unit 34 compares the acceleration threshold set in step S23 with the acceleration (impact value) at the first timing to determine whether or not an impact occurred at the first timing. Specifically, when the acceleration exceeds the acceleration threshold at the first timing, the determination unit 34 can determine that an impact was applied to the vehicle V at the first timing.

[0091] By adopting such a judgment method, the judgment unit 34 can accurately detect whether or not an impact has been applied to the vehicle V at the first timing, and can suppress erroneous detection that an impact has been applied to the vehicle V when acceleration of the vehicle V occurs due to, for example, wind, an earthquake, or movement in a parking space.

[0092] FIG. 13 is a flowchart for explaining an example of the overall operation of the impact detection device 30. As shown in FIG.

[0093] In step S31, the acquisition unit 31 acquires information about acceleration from the acceleration sensor 10 of the vehicle V.

[0094] In step S32, the storage unit 32 stores information regarding the acceleration and the passage of time during a predetermined period.

[0095] In step S33, the speed calculation unit 33 calculates the speed at each timing in a predetermined period based on the information stored in the storage unit 22.

[0096] In step S34, the determination unit 34 determines whether or not an impact has been applied to the vehicle V at each timing, using an acceleration threshold value that has been set based on the speed at each timing.

[0097] As described above, according to the impact detection device 30 according to the second embodiment of the present disclosure, the acceleration threshold for determining whether or not an impact has been applied to the vehicle V at a first timing in a predetermined period is changed based on the speed of the vehicle V at a second timing a predetermined time after the first timing. If an impact is applied to the vehicle V at the first timing, for example, if a sudden acceleration occurs in the vehicle V, the speed of the vehicle V at the second timing after the predetermined time is considered to be close to 0. Therefore, if the speed of the vehicle V at the second timing is less than the speed threshold, the first timing is considered to be a timing at which it is highly likely that an impact has been applied to the vehicle V. On the other hand, if the speed of the vehicle V at the second timing is equal to or greater than the speed threshold, the first timing is considered to be a timing at which it is highly likely that the speed of the vehicle V has increased due to a cause other than an impact.

[0098] Therefore, if the speed of the vehicle V at the second timing is less than the speed threshold, the acceleration threshold for comparison with the acceleration at the first timing is set to a relatively large first value, and if the speed of the vehicle V at the second timing is less than the speed threshold, the acceleration threshold is set to a second value smaller than the first value.By comparing the acceleration at the first timing with the acceleration threshold, it is possible to accurately determine whether or not an impact has occurred to the vehicle V at the first timing.

[0099] In addition, in the impact detection device of the above-mentioned embodiment, the notation "··· part" used for each component can be replaced with other notations such as "··· circuit", "··· assembly", "··· device", "··· unit", or "··· module", as mentioned above.

[0100] Furthermore, the impact detection device of the above-described embodiment may perform signal control by, for example, causing the CPU to execute a program installed in the ROM.

[0101] However, the program executed by the impact detection device may be provided as a file in an installable or executable format recorded on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, a digital versatile disk (DVD), etc. Alternatively, the program may be downloaded via a network and executed by a computer.

[0102] Also, at least a part of the functions of the impact detection device may be realized by a dedicated hardware circuit that does not have a CPU.

[0103] In this way, the impact detection device of the above-mentioned embodiment can be realized by software, hardware, or software in cooperation with hardware. The impact detection device of the above-mentioned embodiment can also be realized by a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or by any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium. The program product is a computer-readable medium on which a computer program is recorded.

[0104] Furthermore, each functional block of the shock detection device of the above-mentioned embodiment may be realized partially or entirely as an LSI, which is an integrated circuit, and each process of the shock detection device of the above-mentioned embodiment may be controlled partially or entirely by one LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of one chip that includes some or all of the functional blocks. The LSI may have data input and output. Depending on the degree of integration, the LSI may be called an IC, a system LSI, a super LSI, or an ultra LSI.

[0105] However, the method of integration is not limited to LSI, and may be realized by a dedicated circuit, a general-purpose processor, or a dedicated processor. Also, after LSI manufacture, a programmable FPGA (Field Programmable Gate Array) or a reconfigurable processor that can reconfigure the connections and settings of circuit cells inside the LSI may be used. Each process of the impact detection device of the above-mentioned embodiment may be realized as digital processing or analog processing.

[0106] Furthermore, if a new integrated circuit technology that can replace LSI appears due to the progress of semiconductor technology or a derivative technology, it is possible to integrate the functional blocks using that technology. The application of biotechnology is also a possibility.

[0107] <Summary of this disclosure> The impact detection device disclosed herein includes a memory circuit that stores the acceleration applied to the vehicle in relation to the passage of time, and a determination circuit that determines whether or not an impact has been applied to the vehicle at each timing during a specified period based on the rate of change of the acceleration during the specified period.

[0108] In the impact detection device disclosed herein, the judgment circuit judges whether or not an impact has been applied to the vehicle for each timing based on whether or not the acceleration at each timing during the specified period is greater than or equal to a specified acceleration threshold, and changes the acceleration threshold used for the judgment at that timing based on the rate of change for that timing.

[0109] In the impact detection device disclosed herein, the judgment circuit sets the acceleration threshold to a first value when the rate of change is less than a predetermined value, and sets the acceleration threshold to a second value smaller than the first value when the rate of change is greater than or equal to the predetermined value.

[0110] In the impact detection device of the present disclosure, the determination circuit changes the predetermined value at each timing during the predetermined period based on the acceleration at each timing.

[0111] The impact detection device disclosed herein comprises a memory circuit that stores the vehicle's speed and acceleration in association with the passage of time, and a judgment circuit that judges whether or not an impact has been applied to the vehicle at a first timing based on whether the acceleration at the first timing is greater than or equal to a predetermined acceleration threshold, and the judgment circuit changes the acceleration threshold based on the speed at a second timing that is a predetermined time after the first timing.

[0112] In the impact detection device disclosed herein, the judgment circuit sets the acceleration threshold to a first value if the velocity at the second timing is greater than or equal to a predetermined velocity threshold, and sets the acceleration threshold to a second value smaller than the first value if the velocity at the second timing is less than the velocity threshold.

[0113] The impact detection device of the present disclosure further includes a speed calculation circuit that performs filtering processing on the acceleration of the vehicle and calculates the speed of the vehicle based on the acceleration after filtering.

[0114] The impact detection method disclosed herein stores the acceleration applied to a vehicle in relation to the passage of time, and determines whether or not an impact has been applied to the vehicle at each timing during a specified period based on the rate of change of the acceleration during the specified period.

[0115] The impact detection method disclosed herein stores a vehicle's speed in association with the passage of time, and determines whether or not an impact has been applied to the vehicle at a first timing based on whether the acceleration at the first timing is greater than or equal to a predetermined acceleration threshold, and in determining whether or not an impact has been applied to the vehicle, changes the first speed threshold based on the speed at a second timing that is a predetermined time after the first timing. [Industrial Applicability]

[0116] The present disclosure is useful for an impact detection device that determines whether or not an impact has been applied to a vehicle. [Explanation of symbols]

[0117] 100 Impact Detection System 10 Acceleration Sensor 20,30 Impact detection device 21 Acquisition Department 22 Memory section 23 Rate of change calculation section 24 Judgment section 31 Acquisition Department 32 Storage section 33 Speed ​​calculation section 34 Judgment section

Claims

1. a memory circuit that stores the acceleration generated in the vehicle in association with the passage of time; a determination circuit that determines whether or not an impact has been applied to the vehicle at each timing in a predetermined period based on a rate of change of the acceleration during the predetermined period; An impact detection device comprising:

2. The determination circuit includes: determining whether or not an impact has been applied to the vehicle for each timing based on whether or not the acceleration at each timing in the predetermined period is equal to or greater than a predetermined acceleration threshold; changing the acceleration threshold value used for the determination at each timing based on the rate of change at that timing; 2. The shock detection device of claim 1.

3. the determination circuit sets the acceleration threshold to a first value when the rate of change is less than a predetermined value, and sets the acceleration threshold to a second value smaller than the first value when the rate of change is equal to or greater than the predetermined value.

3. The shock detection device according to claim 2.

4. the determination circuit changes the predetermined value at each timing in the predetermined period based on the acceleration at each timing.

4. The shock detection device according to claim 3.

5. a memory circuit for storing the vehicle speed and acceleration in association with the passage of time; a determination circuit that determines whether or not an impact has been applied to the vehicle at a first point in time based on whether or not the acceleration at the first point in time is equal to or greater than a predetermined acceleration threshold value; Equipped with the determination circuit changes the acceleration threshold value based on the speed at a second timing that is a predetermined time after the first timing. Impact detection device.

6. the determination circuit sets the acceleration threshold to a first value when the speed at the second timing is equal to or greater than a predetermined speed threshold, and sets the acceleration threshold to a second value smaller than the first value when the speed at the second timing is less than the speed threshold.

6. The shock detection device according to claim 5.

7. A speed calculation circuit is further provided for filtering the acceleration of the vehicle and calculating the speed of the vehicle based on the acceleration after filtering, The memory circuit stores the calculated speed of the vehicle.

7. An impact detection device according to claim 5 or 6.

8. The acceleration generated by the vehicle is stored in association with the passage of time, determining whether or not an impact has been applied to the vehicle at each timing in a predetermined period based on a rate of change of the acceleration during the predetermined period; Impact detection method.

9. whether or not an impact has been applied to the vehicle at each timing in the predetermined period is determined based on whether or not the acceleration at each timing in the predetermined period is equal to or greater than a predetermined acceleration threshold; The acceleration at each timing during the predetermined period is changed based on a rate of change at each timing. The shock detection method according to claim 8.

10. If the rate of change is less than a predetermined value, the acceleration threshold is set to a first value; When the rate of change is equal to or greater than the predetermined value, the acceleration threshold is set to a second value that is smaller than the first value. The shock detection method according to claim 9.

11. The predetermined value at each timing of the predetermined period is changed based on the acceleration at each timing. The shock detection method according to claim 10.

12. storing the vehicle speed and acceleration in relation to time; determining whether an impact has been applied to the vehicle at a first point in time based on whether the acceleration at the first point in time is equal to or greater than a predetermined acceleration threshold; 1. A method for detecting an impact, comprising: In determining whether or not an impact has been applied to the vehicle, the acceleration threshold value is changed based on the speed at a second timing that is a predetermined time after the first timing. Impact detection method.

13. When the speed at the second time point is equal to or greater than a predetermined speed threshold, the acceleration threshold is set to a first value, and when the speed at the second time point is less than the speed threshold, the acceleration threshold is set to a second value smaller than the first value. The shock detection method according to claim 12.

14. The speed of the vehicle is calculated based on the acceleration after the filtering process and stored.

14. The shock detection method according to claim 12 or 13.

Images