Collision detection device and collision detection method

Abstract

To suppress false detection of frontal collision due to impact in association with closing of a front hood.SOLUTION: A collision detection device, which is applied to a vehicle having a food lock at a vehicle front end center part, comprises: a first acceleration sensor which is located at the vehicle front end center part; a second acceleration sensor which is located on a rear side of the vehicle with respect to the first acceleration sensor; a food opening / closing sensor; and one or more processors which determine that frontal collision has occurred when conditions such that first acceleration detected by the first acceleration sensor is higher than a first collision determination threshold and second acceleration detected by the second acceleration sensor is higher than a second collision determination threshold are satisfied. The one or more processors execute: threshold rise processing for changing the first collision determination threshold from a basic value to a correction value larger than the basis value in response to detection of opening of the front hood; and processing for returning the first collision determination threshold to the basis value in response to lapse of a prescribed time after detection of closing of the front hood.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a technique for detecting a frontal collision of a vehicle. [Background technology]

[0002] Patent Document 1 discloses a vehicle occupant protection system. In this system, a collision judgment is performed using a first and a second acceleration sensor to judge whether or not an occupant protection device such as an airbag should be activated. The first acceleration sensor is provided at the front of the vehicle, and the second acceleration sensor is provided at the center of the body of the vehicle. In order to prevent erroneous activation of the occupant protection device due to the use of only the output of the first acceleration sensor, the system activates the occupant protection device on the condition that each of the accelerations detected by the first and second acceleration sensors exceeds a judgment threshold. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-326822 A Summary of the Invention [Problem to be solved by the invention]

[0004] Vehicles such as those described in the patent documents, in which a first acceleration sensor located in the center of the front end of the vehicle and a second acceleration sensor located rearward of the first acceleration sensor are used to detect a frontal collision of the vehicle, have the following problem: If a hood lock that locks the front hood is located near the first acceleration sensor, the first acceleration sensor is more likely to detect high acceleration due to the impact (for convenience of explanation, referred to as impact I) associated with the closing of the front hood.

[0005] Even if the above-mentioned impact I is large, unless the second acceleration sensor detects high acceleration, a frontal collision will not be erroneously detected as a result of the impact I. However, if the second acceleration sensor detects high acceleration due to an accidental factor such as noise generation at the same time that the impact I is applied to the first acceleration sensor, a frontal collision may be erroneously detected as a result of the impact I.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a technology that can suppress false detection of a frontal collision due to the impact associated with the closing of the front hood. [Means for solving the problem]

[0007] The collision detection device according to the present disclosure is configured to detect a front collision of a vehicle having a hood lock for locking a front hood at a front end center of the vehicle that is located at the front end of the vehicle and at the center in the vehicle left-right direction. The collision detection device includes a first acceleration sensor, a second acceleration sensor, a hood opening / closing sensor, and one or more processors. The first acceleration sensor is disposed at the front end center of the vehicle. The second acceleration sensor is disposed rearward of the first acceleration sensor. The hood opening / closing sensor detects opening / closing of the front hood. The one or more processors determine that a front collision has occurred when a condition is satisfied that a first acceleration detected by the first acceleration sensor is higher than a first collision determination threshold and a second acceleration detected by the second acceleration sensor is higher than a second collision determination threshold. The one or more processors then execute a threshold increase process for changing the first collision determination threshold from a basic value to a correction value larger than the basic value in response to detection by the hood opening / closing sensor that the front hood is opened, and a process for returning the first collision determination threshold to the basic value in response to the lapse of a predetermined time from detection by the hood opening / closing sensor that the front hood is closed.

[0008] A collision detection method according to the present disclosure is a method for detecting a frontal collision of a vehicle having a hood lock for locking a front hood at a front end center of the vehicle that is located at the front end of the vehicle and at the center in the vehicle left-right direction. The collision detection method includes determining that a frontal collision has occurred when a condition is satisfied that a first acceleration detected by a first acceleration sensor arranged at the front end center of the vehicle is higher than a first collision determination threshold and a second acceleration detected by a second acceleration sensor arranged rearward of the first acceleration sensor is higher than a second collision determination threshold, executing a threshold increase process for changing the first collision determination threshold from a basic value to a correction value larger than the basic value in response to detection that the front hood is opened by a hood opening / closing sensor that detects opening and closing of the front hood, and executing a process for returning the first collision determination threshold to the basic value in response to the lapse of a predetermined time from detection that the front hood is closed by the hood opening / closing sensor. Effect of the Invention

[0009] According to the present disclosure, by changing the first collision determination threshold in the above-described manner in response to the opening and closing of the front hood, it is possible to suppress erroneous detection of a frontal collision caused by the impact accompanying the closing of the front hood. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram showing an example of a configuration of a vehicle equipped with a collision detection device according to an embodiment; [Diagram 2] 4 is a flowchart showing a basic process for detecting a frontal collision according to the embodiment. [Diagram 3] 1A and 1B are diagrams for explaining a problem in detecting a frontal collision using first and second acceleration sensors. [Figure 4] 1A and 1B are diagrams for explaining a problem in detecting a frontal collision using first and second acceleration sensors. [Diagram 5] 3 is a flowchart showing a process related to switching of a first collision determination threshold TH1 in FIG. 2. [Figure 6] 10 is a diagram for explaining the relationship between a basic value TH1b and a correction value TH1c of the first collision determination threshold TH1. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 1. Vehicle configuration FIG. 1 is a diagram showing an example of the configuration of a vehicle 10 equipped with a collision detection device 1 according to an embodiment.

[0012] The vehicle 10 has a front hood 12. The front hood 12 opens and closes a power room provided at the front of the vehicle 10. The power room houses a drive device (e.g., at least one of an internal combustion engine and an electric motor) of the vehicle 10. In an example in which the drive device includes an internal combustion engine, the front hood 12 is also called an engine hood, and the power room is also called an engine room or an engine compartment.

[0013] The vehicle 10 has a hood lock 14 that locks the front hood 12. As shown in FIG. 3 described below, the front hood 12 has a front-opening structure in which the front side of the vehicle opens. For this reason, the hood lock 14 is disposed on the front end side of the front hood 12. In other words, the hood lock 14 is disposed in a vehicle front end center portion 16 that is located at the front end of the vehicle 10 and in the center of the vehicle in the left-right direction. More specifically, the hood lock 14 is attached to a vehicle body component located in the vehicle front end center portion 16.

[0014] A first acceleration sensor 18 is disposed at the vehicle front center portion 16. More specifically, the first acceleration sensor 18 is attached to a vehicle body component located at the vehicle front center portion 16. The first acceleration sensor 18 detects a first acceleration (more specifically, a longitudinal acceleration) A1 occurring at the attachment portion of the first acceleration sensor 18. The vehicle body component to which the first acceleration sensor 18 is attached is separate from, or may be the same as, the vehicle body component to which the hood lock 14 is attached.

[0015] The vehicle 10 further includes a second acceleration sensor 20. The second acceleration sensor 20 is disposed rearward of the first acceleration sensor 18. For example, the second acceleration sensor 20 is disposed at the center of the vehicle body in the vehicle longitudinal direction and the vehicle transverse direction. More specifically, the second acceleration sensor 20 is housed in a device attached to a vehicle body component (e.g., a floor panel) at the center of the vehicle body. The device may be, for example, an airbag ECU included in the ECU 30 described later. Alternatively, the second acceleration sensor 20 may be attached to a vehicle body component located at the center of the vehicle body. The second acceleration sensor 20 detects a second acceleration (more specifically, a longitudinal acceleration) A2 occurring at a mounting position of the second acceleration sensor 20.

[0016] The vehicle 10 is equipped with a hood opening / closing sensor 22 and a wheel speed sensor 24. The hood opening / closing sensor 22 detects the opening / closing of the front hood 12, in other words, the unlocked / locked state of the hood lock 14. The wheel speed sensors 24 are disposed corresponding to each wheel 26 of the vehicle 10. The wheel speed sensors 24 are used to acquire the speed of the vehicle 10 (vehicle speed V).

[0017] The vehicle 10 includes an electronic control unit (ECU) 30. The ECU 30 is a computer that controls the vehicle 10. The ECU 30 includes one or more processors 32 (hereinafter simply referred to as the processor 32) and one or more storage devices 34 (hereinafter simply referred to as the storage device 34). The processor 32 executes various processes. The various processes include a process related to "front collision detection" described below and a process related to the operation of the airbag device 40. The storage device 34 stores various information required for the processes by the processor 32. The processor 32 executes a computer program, thereby realizing the various processes by the ECU 30. The computer program is stored in the storage device 34. Alternatively, the computer program may be recorded in a computer-readable recording medium. The ECU 30 may be configured by combining a plurality of ECUs that can communicate with each other, for example, by CAN (Controller Area Network) communication.

[0018] As an example of an occupant protection device for use in a collision of the vehicle 10, the vehicle 10 is equipped with an airbag device 40. The airbag device 40 is configured to deploy an airbag in response to a command from the ECU 30 and detection of a frontal collision, which will be described later.

[0019] 2. Frontal collision detection In order to detect a frontal collision of the vehicle 10 (i.e., a collision from the front of the vehicle 10), the "collision detection device 1" of this embodiment is configured to include a first acceleration sensor 18, a second acceleration sensor 20, a hood opening / closing sensor 22, and a processor 32.

[0020] 2-1. Basic processing 2 is a flowchart showing a basic process for detecting a frontal collision according to the embodiment. The process of this flowchart is repeatedly executed by the processor 32 of the ECU 30 while the system of the vehicle 10 is running.

[0021] In FIG. 2, in step S100, the processor 32 obtains a first acceleration A1 and a second acceleration A2 using the first acceleration sensor 18 and the second acceleration sensor 20, respectively.

[0022] Next, in step S102, the processor 32 determines whether or not a condition C is satisfied, that is, the first acceleration A1 is higher than a first collision determination threshold TH1 and the second acceleration A2 is higher than a second collision determination threshold TH2. The first collision determination threshold TH1 and the second collision determination threshold TH2 are, for example, determined in advance and stored in the storage device 34. The first collision determination threshold TH1 is changed between a basic value TH1b and a correction value TH1c by a process shown in FIG. 5, which will be described later.

[0023] If the above condition C is not satisfied (step S102; No), the process proceeds to RETURN. On the other hand, if the condition C is satisfied (step S102; Yes), the process proceeds to step S104. In step S104, the processor 32 determines that a frontal collision has occurred. That is, the processor 32 detects a frontal collision.

[0024] 2-2.Challenges Next, a problem in detecting a frontal collision using the first and second acceleration sensors 18, 20 will be described with reference to FIG. 3 and FIG. 4(A) to FIG. 4(C).

[0025] As described above, the first acceleration sensor 18 is disposed in the vehicle front end center portion 16 (see FIG. 1) similarly to the hood lock 14. That is, the first acceleration sensor 18 is disposed near the hood lock 14. For this reason, as shown in FIG. 3, if the front end position of the front hood 12 is high when the user of the vehicle 10 closes the front hood 12, a large impact is likely to be transmitted to the first acceleration sensor 18. As a result, the first acceleration sensor 18 is likely to detect a large first acceleration A1. Hereinafter, for convenience of explanation, the impact generated in association with the closing of the front hood 12 is also simply referred to as "impact I."

[0026] FIG. 4A shows an example of a time waveform of the first acceleration A1 detected by the first acceleration sensor 18 when the above-mentioned impact I occurs. In this example, the first acceleration A1 (impact G) that exceeds the basic value TH1b of the first collision determination threshold TH1 due to the impact I is detected. The basic value TH1b is, for example, 20 G. A large change in the first acceleration A1 as shown in FIG. 4A caused by the impact I occurs over a period of, for example, about 10 milliseconds. In addition, the mounting position of the first acceleration sensor 18 on the vehicle 10 (vehicle body) is a position where the first acceleration A1 exceeds the first collision determination threshold TH1 depending on the magnitude of the impact I when the front hood 12 is closed in the case where the basic value TH1b is used as the first collision determination threshold TH1.

[0027] FIG. 4B shows an example of a time waveform of the second acceleration A2 detected by the second acceleration sensor 20 when the same impact I as shown in FIG. 4A occurs. This time waveform shows the influence of the impact I. However, in this example, the second acceleration A2 does not exceed the second collision determination threshold TH2 (e.g., 1.3G). Therefore, even if the first acceleration A1 exceeds the first collision determination threshold TH1 (basic value TH1b), a frontal collision is not erroneously detected due to the impact I. Therefore, the airbag device 40 does not malfunction in response to the occurrence of the impact I. In addition, in the example shown in FIG. 4B, it can be said that the redundancy achieved by using the two acceleration sensors 18 and 20 for frontal collision detection functions appropriately.

[0028] On the other hand, Fig. 4(C) shows an example in which accidental noise is superimposed on the output of the second acceleration sensor 20 at the same time as the occurrence of the same impact I as shown in Fig. 4(A). In this example, the second acceleration A2 exceeds the second collision determination threshold TH2 due to the influence of the superimposed noise. As a result, in this example, the condition that the first acceleration A1 is higher than the first collision determination threshold TH1 (basic value TH1b) and the second acceleration A2 is also higher than the second collision determination threshold TH2 is met, and a frontal collision is erroneously detected due to the impact I.

[0029] Even if the output of the second acceleration sensor 20 does not include noise as shown in Fig. 4(C), the second acceleration sensor 20 may detect a high second acceleration A2 due to factors such as an accidental application of another large impact to the second acceleration sensor 20 at the same time as the occurrence of the impact I. If the second acceleration A2 exceeds the second collision determination threshold TH2 as a result, a frontal collision will be erroneously detected due to the impact I, as in the example shown in Fig. 4(C). Note that an example of the accidental application of another large impact here corresponds to a case where a user of the vehicle 10 mistakenly applies a strong impact to the ECU 30 in which the second acceleration sensor 20 is built.

[0030] 2-3. Measures In order to suppress erroneous detection of a frontal collision caused by the impact I, in this embodiment, the processor 32 executes a "threshold increase process" in response to detection by the hood opening / closing sensor 22 that the front hood 12 is open. This threshold increase process is a process for changing the first collision determination threshold TH1 from a basic value TH1b to a correction value TH1c that is larger than the basic value TH1b. More specifically, in this embodiment, the processor 32 executes the threshold increase process on the condition that the vehicle speed V is zero.

[0031] In addition, in this embodiment, the processor 32 executes a process of returning the first collision determination threshold TH1 to the basic value TH1b in response to the lapse of a predetermined time T from when the hood opening / closing sensor 22 detects that the front hood 12 is closed.

[0032] Fig. 5 is a flowchart showing a process related to switching of the first collision determination threshold TH1 in Fig. 2. The processor 32 executes the process of this flowchart in parallel with the process of the flowchart shown in Fig. 2.

[0033] In FIG. 5, in step S200, the processor 32 acquires vehicle speed information. The vehicle speed information is information on the vehicle speed V of the vehicle 10, and is based on the output of the wheel speed sensor 24, for example. Next, in step S202, it is determined whether the vehicle speed V is 0 km / h. As a result, if the vehicle speed V is not 0 km / h (step S202; No), the process returns to step S200. On the other hand, if the vehicle speed V is 0 km / h (step S202; Yes), the process proceeds to step S204.

[0034] In step S204, the processor 32 acquires hood state information. The hood state information is information indicating whether the front hood 12 is open or closed, and is based on the output of the hood opening / closing sensor 22.

[0035] In step S206 following step S204, processor 32 determines whether or not front hood 12 is open based on the hood state information. If the result is that front hood 12 is closed (step S206; No), the process returns to step S200. On the other hand, if front hood 12 is open (step S206; Yes), the process proceeds to step S208.

[0036] The process of step S208 corresponds to the above-mentioned "threshold increase process." That is, in step S208, the processor 32 changes the first collision determination threshold TH1 from the basic value TH1b to the correction value TH1c. The basic value TH1b is, for example, a value determined in advance. As already described, the basic value TH1b is, for example, 20 G. The correction value TH1c is determined to be a value larger than the basic value TH1b. The correction value TH1c is, for example, a value determined in advance.

[0037] FIG. 6 is a diagram for more specifically explaining the relationship between the basic value TH1b of the first collision determination threshold TH1 and the correction value TH1c. In FIG. 6, the time waveform of the first acceleration A1 including the influence of the impact I is shown, similarly to FIG. 4(A). As shown in FIG. 6, the correction value TH1c is determined, for example, to be larger than the assumed maximum value of the first acceleration A1 caused by the impact I accompanying the closing of the front hood 12. More specifically, the correction value TH1c is determined, for example, to be a value large with a sufficient margin with respect to the above assumed maximum value. The assumed maximum value can be specified, for example, by performing an experiment or a simulation in advance.

[0038] In step S210 following step S208, the processor 32 acquires hood status information. In addition, a predetermined small amount of time elapses between the acquisition of the hood status information in step S204 and the acquisition of the hood status information in step S210.

[0039] In step S212 following step S210, processor 32 determines whether or not front hood 12 is closed based on the hood state information. If front hood 12 is open (step S212; No), the process returns to step S200. On the other hand, if front hood 12 is closed (step S212; Yes), the process proceeds to step S214.

[0040] In step S214, processor 32 waits for a predetermined time T to elapse, which starts from the time when a positive determination is made in step S12 (i.e., when it is detected that front hood 12 is closed). More specifically, predetermined time T is determined to include a period during which impact I caused by the closing of front hood 12 acts on vehicle front end center portion 16 (e.g., a period of about 10 ms shown in FIG. 6), and is, for example, 1 second. After predetermined time T has elapsed, the process proceeds to step S216.

[0041] In step S216, the processor 32 executes a process of returning the first collision determination threshold TH1 from the correction value TH1c to the basic value TH1b.

[0042] 3.Effects As described above, according to the collision detection device 1 of this embodiment, in response to detection that the front hood 12 is open, the first collision determination threshold TH1 is changed from the basic value TH1b to a correction value TH1c larger than the basic value TH1b (threshold increase process). Then, in response to the lapse of a predetermined time T from detection that the front hood 12 is closed, the first collision determination threshold TH1 is returned to the basic value TH1b. By increasing the first collision determination threshold TH1 from the opening of the front hood 12 until immediately after it is closed in this manner, it is possible to suppress erroneous detection of a frontal collision even if the second acceleration sensor 20 accidentally detects a high second acceleration A2 at the same time as the occurrence of the impact I. This leads to suppression of erroneous operation of the airbag device 40.

[0043] Also, broadly speaking, the above-mentioned threshold increase process may be executed even when the vehicle speed V is not zero. In addition, it is assumed that the opening and closing of the front hood 12 by the user of the vehicle 10 is basically executed when the vehicle speed V is zero. Therefore, according to the present embodiment, the above-mentioned threshold increase process is executed on the condition that the vehicle speed V is zero. This makes it possible to more accurately grasp the impact I that occurs when the user closes the front hood 12, while suppressing erroneous detection of a frontal collision due to the influence of the impact I.

[0044] Furthermore, according to this embodiment, the above-mentioned predetermined time T is determined so as to include a period during which the impact I caused by the closing of the front hood 12 acts on the vehicle front end central portion 16 (see the process of step S214). This makes it possible to more reliably prevent the first acceleration A1 from exceeding the first collision determination threshold value TH1 due to the effect of the impact I.

[0045] Furthermore, according to this embodiment, the above-mentioned correction value TH1c is determined to be greater than the expected maximum value of the first acceleration A1 caused by the impact I accompanying the closing of the front hood 12. This makes it possible to more reliably prevent the first acceleration A1 from exceeding the first collision determination threshold value TH1 due to the effect of the impact I. [Explanation of symbols]

[0046] REFERENCE SIGNS LIST 1 collision detection device, 10 vehicle, 12 front hood, 14 hood lock, 16 vehicle front end center portion, 18 first acceleration sensor, 20 second acceleration sensor, 22 hood opening / closing sensor, 24 wheel speed sensor, 26 wheel, 30 electronic control unit (ECU), 32 processor, 34 storage device, 40 airbag device

Claims

1. A collision detection device for detecting a front collision of a vehicle having a hood lock for locking a front hood at a front end center portion of the vehicle that is located at the front end of the vehicle and at the center in the left-right direction of the vehicle, A first acceleration sensor disposed at a front center portion of the vehicle; a second acceleration sensor disposed rearward of the first acceleration sensor; a hood opening / closing sensor for detecting the opening / closing of the front hood; one or more processors that determine that the frontal collision has occurred when a condition is satisfied that a first acceleration detected by the first acceleration sensor is higher than a first collision determination threshold and a second acceleration detected by the second acceleration sensor is higher than a second collision determination threshold; Equipped with The one or more processors: a threshold raising process for changing the first collision determination threshold from a basic value to a correction value larger than the basic value in response to detection by the hood opening / closing sensor that the front hood is opened; A process of returning the first collision determination threshold to the basic value in response to a lapse of a predetermined time from the detection by the hood opening / closing sensor that the front hood is closed; Run A collision detection device comprising:

2. The one or more processors execute the threshold increasing process on the condition that the speed of the vehicle is zero.

2. The collision detection device according to claim 1.

3. The predetermined time is determined so as to include a period during which an impact caused by the closing of the front hood acts on the center of the front end of the vehicle.

3. The collision detection device according to claim 1, wherein the collision detection device is a collision detection device for detecting a collision between a collision object and a collision target.

4. The correction value is determined to be greater than an assumed maximum value of the first acceleration caused by an impact accompanying the closing of the front hood.

3. The collision detection device according to claim 1, wherein the collision detection device is a collision detection device for detecting a collision between a collision object and a collision target.

5. A collision detection method for detecting a front collision of a vehicle having a hood lock for locking a front hood at a front end center portion of the vehicle that is located at the front end of the vehicle and at the center in the left-right direction of the vehicle, comprising: determining that the frontal collision has occurred when a condition is satisfied that a first acceleration detected by a first acceleration sensor disposed in a front center portion of the vehicle is higher than a first collision determination threshold, and a second acceleration detected by a second acceleration sensor disposed rearward of the first acceleration sensor on the vehicle is higher than a second collision determination threshold; executing a threshold raising process for changing the first collision determination threshold from a basic value to a correction value larger than the basic value in response to detection by a hood opening / closing sensor that detects opening / closing of the front hood that the front hood is opened; executing a process of returning the first collision determination threshold to the basic value in response to a lapse of a predetermined time from the detection by the hood opening / closing sensor that the front hood is closed; Includes 13. A collision detection method comprising:

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