Submergence detection device, vehicle and submergence detection method

Abstract

The present invention provides a submergence detection device, a vehicle and a submergence detection method for detecting the submergence of an acoustic wave sensor with high accuracy. The submergence detection device (19) for detecting the submergence of at least two acoustic wave sensors (2a) and (2b) mounted on a vehicle (1) comprises: an acquisition unit (20) for acquiring information on the time from when a first acoustic wave sensor (2a) emits an acoustic wave (S) to when the second acoustic wave sensor (2b) detects the acoustic wave (S); and a control unit (21) for determining whether both the first acoustic wave sensor (2a) and the second acoustic wave sensor (2b) are submerged based on the time information.

Description

Technical Field

[0001] The invention relates to a submergence detection device, a vehicle and a submergence detection method. Background Art

[0002] In the past, obstacle detection devices have become popular, in which multiple acoustic wave sensors are mounted on a vehicle and obstacles around the vehicle are detected based on acoustic waves sent or received by the acoustic wave sensors. In such obstacle detection devices, if moisture adheres to the surface of the acoustic wave sensors, the obstacle detection accuracy decreases and driving assistance may not be properly provided.

[0003] Therefore, Patent Document 1 discloses a technique for determining whether or not the vibration characteristics of the reverberation of the sound wave sensor have changed, and assisting driving based on the determination result.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-15493 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] For example, sometimes the acoustic wave sensor is immersed in water (hereinafter referred to as "flooding") due to flooding of the road, etc., and the occupants of the vehicle do not notice this. However, in the technology of Patent Document 1, only the attachment of water to the acoustic wave sensor is detected, and the flooding of the acoustic wave sensor is not detected.

[0009] An object of the present invention is to provide a submergence detection device, a vehicle, and a submergence detection method for detecting submergence of an acoustic wave sensor with high accuracy.

[0010] Solutions to the problem

[0011] The submergence detection device of the present invention detects the submergence of at least two sound wave sensors mounted on a vehicle, and comprises: an acquisition unit, which acquires information on the time from the emission of a sound wave by a first sound wave sensor to the detection of the sound wave emitted by the first sound wave sensor by a second sound wave sensor; and a control unit, which determines whether both the first sound wave sensor and the second sound wave sensor are submerged based on the time information.

[0012] A vehicle of the present invention includes at least two acoustic wave sensors, and includes: the above-mentioned submergence detection device; and an output device for notifying a vehicle occupant of the risk of submergence of the vehicle.

[0013] The submergence detection method of the present invention is a submergence detection method for detecting the submergence of at least two sound wave sensors mounted on a vehicle, comprising the following steps: a step of acquiring information on the time from when a first sound wave sensor emits a sound wave to when a second sound wave sensor detects the sound wave emitted from the first sound wave sensor; and a step of determining whether both the first sound wave sensor and the second sound wave sensor are submerged based on the time information.

[0014] Effects of the Invention

[0015] According to the present invention, submergence of the acoustic wave sensor can be detected with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a diagram showing the structure of a vehicle including the submergence detection device according to the first embodiment of the present invention.

[0017] Figure 2 is a block diagram showing the structure of an acoustic wave sensor.

[0018] Figure 3 It is a block diagram showing the structure of the sonar ECU.

[0019] Figure 4 This is a flowchart showing the actions of implementation mode 1.

[0020] Figure 5 It is a diagram showing the output signal and the received signal when the mask period is shortened.

[0021] Figure 6 This is a flowchart showing the actions of implementation mode 2.

[0022] Figure 7 This is a diagram showing the noise monitoring period in the third embodiment.

[0023] Description of Reference Numerals

[0024] 1 Vehicle

[0025] 2a~2h Acoustic sensor

[0026] 3 Sonar ECU

[0027] 4 Drive system ECU

[0028] 5 Braking system ECU

[0029] 6 Output Devices

[0030] 7 Transmission lines

[0031] 8 In-car LAN

[0032] 9 Piezoelectric element

[0033] 10. Driving Circuit

[0034] 11 Receiving Circuit

[0035] 12 Sensor control unit

[0036] 13. Timer

[0037] 14 Waveform memory

[0038] 15. Decision circuit

[0039] 16 Communication circuit

[0040] 17 Threshold Memory

[0041] 18 Obstacle Detection Device

[0042] 19 Submergence detection device

[0043] 20 Acquisition Department

[0044] 21 Control Department

[0045] S sound wave DETAILED DESCRIPTION

[0046] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0047] (Implementation Method 1)

[0048] Figure 1 2 shows a structure of a vehicle 1 equipped with a submergence detection device according to Embodiment 1 of the present invention. The vehicle 1 includes eight acoustic wave sensors 2a to 2h, a sonar ECU (Electronic Control Unit) 3, a drive system ECU 4, a brake system ECU 5, and an output device 6.

[0049] The acoustic wave sensors 2a to 2h and the sonar ECU 3 are connected to each other via a transmission line 7. In addition, the sonar ECU 3, the drive system ECU 4, the brake system ECU 5, and the output device 6 are connected to each other via the in-vehicle LAN 8. In addition, in the present embodiment, the transmission line 7 is composed of a dedicated line separated from the in-vehicle LAN 8, but it may be integrally formed with the in-vehicle LAN 8.

[0050] The acoustic wave sensors 2a to 2h are sensors mounted on the vehicle 1 to transmit and receive acoustic waves such as ultrasonic waves to detect obstacles around the vehicle 1. The acoustic wave sensors 2a to 2d are arranged side by side at intervals in the vehicle width direction on the front bumper of the vehicle 1. In addition, the acoustic wave sensors 2e to 2h are arranged side by side at intervals in the vehicle width direction on the rear bumper of the vehicle 1.

[0051] That is, the acoustic wave sensors 2 a to 2 d emit acoustic waves toward the front of the vehicle 1 , and the acoustic wave sensors 2 e to 2 h emit acoustic waves toward the rear of the vehicle 1 .

[0052] The sonar ECU 3 is for comprehensively controlling the acoustic wave sensors 2 a to 2 h , and controls the driving system ECU 4 , the braking system ECU 5 , and the output device 6 based on information obtained from the acoustic wave sensors 2 a to 2 h .

[0053] The drive system ECU 4 controls the drive unit based on a signal indicating an operation of the drive unit by the driver, etc. Examples of the drive unit include an engine and the like.

[0054] The brake system ECU5 controls the brake part based on a signal indicating an operation of the brake part by the driver, etc. Examples of the brake part include a brake and the like.

[0055] The output device 6 is a so-called human machine interface (HMI) for exchanging information with the occupants, and includes a notification unit for notifying the occupants of the vehicle 1. Examples of the notification unit include a display and a speaker.

[0056] Next, the structure of the acoustic wave sensors 2a to 2h will be described in detail.

[0057] exist Figure 2 The structure of the acoustic wave sensor 2 a is shown in FIG. The acoustic wave sensor 2 a includes a piezoelectric element 9 , a driving circuit 10 and a receiving circuit 11 are connected to the piezoelectric element 9 , respectively, and the driving circuit 10 and the receiving circuit 11 are connected to a sensor control unit 12 .

[0058] The sensor control unit 12 includes a timer 13, a waveform memory 14, a determination circuit 15, a communication circuit 16, and a threshold memory 17. The timer 13 is connected to the drive circuit 10 and the waveform memory 14 is connected to the receiving circuit 11, and the timer 13 and the waveform memory 14 are connected to the communication circuit 16 via the determination circuit 15. In addition, the communication circuit 16 is connected to the determination circuit 15 via the threshold memory 17 and is also connected to the transmission line 7.

[0059] The piezoelectric element 9 oscillates when a voltage is applied, thereby emitting a pulsed sound wave. When a sound wave reflected by an obstacle or the like enters the piezoelectric element 9, the piezoelectric element 9 expands and contracts in accordance with the change in the sound pressure of the sound wave, and outputs a reception signal generated thereby.

[0060] The driving circuit 10 is a circuit for applying a predetermined voltage to the piezoelectric element 9 to cause the piezoelectric element 9 to emit sound waves, and applies a voltage of, for example, 50 kHz. As a result, the piezoelectric element 9 emits sound waves of a predetermined frequency.

[0061] The receiving circuit 11 rectifies the reception signal output from the piezoelectric element 9 to convert it into the intensity of the sound wave, thereby generating an intensity waveform of the sound wave. In addition, the receiving circuit 11 includes a shielding processing unit that shields the signal input from the piezoelectric element 9.

[0062] The shield processing unit shields the signal output from the piezoelectric element 9 during, for example, the transmission period of the acoustic wave transmitted from the piezoelectric element 9 , thereby preventing the processing capacity of the receiving circuit 11 from being saturated.

[0063] The timer 13 supplies a timing signal for the drive circuit 10 to apply a voltage to the piezoelectric element 9 .

[0064] The waveform memory 14 sequentially stores the intensity values ​​of the intensity waveform of the sound wave generated by the receiving circuit 11 .

[0065] The threshold memory 17 stores in advance the threshold of the sound wave intensity, and the threshold of the sound wave intensity is used by the determination circuit 15 to determine an obstacle.

[0066] The determination circuit 15 compares the intensity value of the intensity waveform of the sound wave stored in the waveform memory 14 with the threshold value stored in the threshold value memory 17, and detects a portion of the intensity waveform whose intensity value exceeds the threshold value.

[0067] Then, the determination circuit 15 calculates information on the time when the intensity value exceeds the threshold value. This time is the time when the sound wave sensor 2a receives the sound wave reflected by the obstacle, and is hereinafter referred to as the sound wave reception time.

[0068] In addition, the determination circuit 15 acquires information of the time when the sound wave is emitted from the piezoelectric element 9 from the timer 13. Hereinafter, this time is referred to as the sound wave emission time.

[0069] The determination circuit 15 calculates the reverberation characteristics of the acoustic wave sensor 2a based on the signal input to the receiving circuit 11 immediately after the acoustic wave sensor 2a transmits the acoustic wave. Examples of the reverberation characteristics include the frequency of the reverberation and the duration of the reverberation.

[0070] Furthermore, the determination circuit 15 outputs information such as the sound wave reception time, the sound wave transmission time, and the reverberation characteristics to the communication circuit 16 .

[0071] The communication circuit 16 outputs information output from the determination circuit 15 to the sonar ECU 3, and outputs control signals input from the sonar ECU 3 to each part of the acoustic wave sensor 2a. The acoustic wave sensors 2b to 2h have the same structure as the acoustic wave sensor 2a, and thus description thereof is omitted.

[0072] Next, the structure of the sonar ECU 3 will be described in detail.

[0073] like Figure 3 As shown, the sonar ECU 3 has an obstacle detection device 18 and a flooding detection device 19. The obstacle detection device 18 and the flooding detection device 19 are connected to the acoustic wave sensors 2a to 2h, the driving system ECU 4, the braking system ECU 5 and the output device 6, respectively.

[0074] The obstacle detection device 18 calculates position information such as the distance and direction from the sound wave sensors 2a to 2h to the obstacle based on information such as the sound wave reception time, sound wave transmission time and sound wave speed detected by each determination circuit 15 of the sound wave sensors 2a to 2h.

[0075] Here, the distance from the acoustic wave sensors 2a to 2h to the obstacle is set as the distance from the vehicle 1 to the obstacle. This calculation method is a prior art, so detailed description is omitted. The obstacle detection device 18 controls the drive system ECU 4, the brake system ECU 5 and the output device 6 based on the calculated obstacle position information.

[0076] The flooding detection device 19 includes an acquisition unit 20 and a control unit 21. The acquisition unit 20 and the control unit 21 are connected.

[0077] The acquisition unit 20 acquires the above-mentioned information on the sound wave sending time and the sound wave receiving time from the determination circuit 15 of the sound wave sensors 2a~2h as the information on the propagation time of the sound wave from the time when the sound wave sensor 2a~2h transmits the sound wave to the time when the sound wave is detected by the sound wave sensor 2a~2h, and acquires the reverberation characteristics of the sound wave sensors 2a~2h.

[0078] It should be noted that the sound wave sensors 2a~2h may also maintain information on the time when the sound wave is sent, and the judgment circuit 15 of the sound wave sensors 2a~2h may calculate the propagation time of the sound wave from the time when the sound wave sensor 2a~2h transmits the sound wave to the time when the sound wave is detected by the sound wave sensor 2a~2h based on the information on the time when the sound wave is sent and the information on the time when the sound wave is received, and the acquisition unit 20 may acquire the information on the propagation time from the judgment circuit 15.

[0079] The control unit 21 determines whether or not at least two of the acoustic wave sensors 2 a to 2 h are submerged based on the information on the propagation time acquired by the acquisition unit 20 .

[0080] Specifically, when the propagation time is less than a predetermined threshold value, the control unit 21 determines that both the acoustic wave sensor that transmits the acoustic wave and the other acoustic wave sensor that receives the acoustic wave are submerged. Furthermore, the control unit 21 controls the drive system ECU 4, the brake system ECU 5, and the output device 6 based on the determination result.

[0081] Furthermore, the control unit 21 controls the receiving circuits 11 of the sound wave sensors 2a to 2h based on the reverberation characteristics acquired by the acquisition unit 20 to shorten the time during which the receiving circuits 11 shield the reception of the sound waves during the transmission period.

[0082] Next, refer to Figure 4 The flowchart of embodiment 1 illustrates the flooding detection method.

[0083] First, in step S1, Figure 1 The piezoelectric element 9 of the acoustic wave sensors 2a to 2h mounted on the vehicle 1 oscillates under the control of the sonar ECU 3, so that the acoustic wave sensors 2a to 2d emit acoustic waves in sequence, and the acoustic wave sensors 2e to 2h emit acoustic waves in sequence. It should be noted that the sonar ECU 3 performs the same control on the acoustic wave sensors 2a to 2d and the acoustic wave sensors 2e to 2h, so the acoustic wave sensors 2a to 2d will be described below.

[0084] like Figure 2 As described above, each of the acoustic wave sensors 2a to 2d is provided with a timer 13. The timers 13 of the acoustic wave sensors 2a to 2d are synchronized with each other. For example, when the acoustic wave sensor 2a emits acoustic waves, the driving circuits 10 of the acoustic wave sensors 2b to 2d are not driven but are in a waiting state.

[0085] In addition, the receiving circuit 11 of the acoustic wave sensors 2a to 2d shields the received signal input from the piezoelectric element 9 during the transmission period of the acoustic wave emitted from the piezoelectric element 9 of the acoustic wave sensor 2a. If the intensity of the signal input from the piezoelectric element 9 of the acoustic wave sensor 2a exceeds the threshold value for determining an obstacle, the signal will be mistakenly identified as an obstacle. Therefore, by performing the above-mentioned shielding process, the misidentification can be eliminated. In addition, instead of the receiving circuit 11 performing the shielding process of the received signal, the determination circuit 15 may perform the shielding process by software processing during the transmission period instead of treating the received signal as a received wave.

[0086] When the transmission period of the sound wave sensor 2a ends and a time sufficient for the reverberation in the air caused by the transmission to completely disappear has passed, the receiving circuit 11 of the sound wave sensors 2a to 2d releases the shielding of reception and inputs the signal from the piezoelectric element 9 during the specified reception period. Thus, the reception signal of the sound wave incident on the piezoelectric element 9 is input to the receiving circuit 11 of the sound wave sensors 2a to 2d. In addition, the following signal is also input to the receiving circuit 11 of the sound wave sensor 2a, that is, the signal of the reverberation of the vibration of the piezoelectric element 9 continuing after the sound wave is transmitted.

[0087] The receiving circuits 11 of the sound wave sensors 2a to 2d respectively generate intensity waveforms based on the received signals of the sound waves, and store the intensity values ​​of the intensity waveforms of the sound waves in the waveform memory 14. In addition, the receiving circuit 11 of the sound wave sensor 2a that has emitted the sound waves stores the intensity values ​​of the intensity waveforms of the sound waves together with the intensity values ​​of the reverberation in the waveform memory 14.

[0088] Furthermore, based on the intensity value of the intensity waveform of the sound wave stored in the waveform memory 14 and the threshold value stored in the threshold value memory 17, the determination circuit 15 of the sound wave sensors 2a to 2d respectively detects the time of receiving the sound wave reflected by the obstacle, i.e., the sound wave reception time, and outputs the information of the sound wave reception time to the sonar ECU 3. In addition, the determination circuit 15 of the sound wave sensors 2a to 2d that have emitted the sound wave outputs the information of the time of emitting the sound wave, i.e., the sound wave sending time, to the sonar ECU 3.

[0089] Then, in step S2 , the determination circuit 15 of the sound wave sensor 2 a that has emitted the sound wave detects the reverberation frequency from the reverberated signal stored in the waveform memory 14 , and outputs the information of the reverberation frequency to the sonar ECU 3 .

[0090] The acquisition unit 20 of the submergence detection device 19 in the sonar ECU 3 acquires information on the sound wave transmission time and the sound wave reception time as the sound wave propagation time information from the determination circuit 15 of the sound wave sensors 2a to 2d, and acquires information on the reverberation frequency of the sound wave sensors 2a to 2d.

[0091] In step S3 , the control unit 21 acquires information on the reverberation frequency from the acquisition unit 20 , and determines whether the reverberation frequency is smaller than a predetermined threshold value Th.

[0092] Here, the piezoelectric element 9 of the acoustic wave sensors 2a to 2d is designed to vibrate naturally at a predetermined frequency in the air. Therefore, the piezoelectric element 9 oscillates at the frequency of the applied voltage while an AC voltage is applied, and vibrates naturally at a predetermined frequency when no voltage is applied, and this vibration is detected as reverberation.

[0093] If water splashed from a water reservoir adheres to the piezoelectric element 9 , the frequency of the reverberation tends to be lower than when no water adheres to the piezoelectric element 9 .

[0094] Therefore, by setting the threshold Th based on the reverberation frequency of the piezoelectric element 9 with moisture attached, it is possible to determine whether moisture is attached to the piezoelectric element 9 of the acoustic wave sensor 2a that emits the acoustic wave, that is, it is possible to determine whether the acoustic wave sensor 2a is in an environment with a lot of moisture.

[0095] When the control unit 21 determines that the reverberation frequency input from the acquisition unit 20 is above the specified threshold value Th, it deems that the acoustic wave sensor 2a is in an environment with little moisture, proceeds to step S4, performs normal processing without changing the settings of the receiving circuit 11 of the acoustic wave sensors 2a~2d, and returns to step S1.

[0096] According to the above flow, the sound wave sensors 2a to 2d that emit sound waves are sequentially changed and the processing of step S1 to step S3 is repeated until it is determined that the reverberation frequency is less than a predetermined threshold value Th.

[0097] On the other hand, when the control unit 21 determines in step S3 that the reverberation frequency input from the acquisition unit 20 is less than the specified threshold value Th, the control unit 21 proceeds to step S5 to control the receiving circuit 11 of the sound wave sensors 2b~2d other than the sound wave sensor 2a that transmits the sound wave, so as to shorten the time for shielding the reception during the transmission of the sound wave.

[0098] For example, Figure 5 As shown, the control unit 21 shortens the time for shielding the reception signal input to the receiving circuit 11 of the acoustic wave sensor 2b during the transmission period of the acoustic wave sensor 2a. That is, the shielding time is shortened in such a way that the receiving circuit 11 of the acoustic wave sensor 2b also receives the reception signal during the transmission period of the acoustic wave sensor 2a.

[0099] Generally speaking, the sound waves emitted from the sound wave sensor 2 a have a directivity of propagating forward, and therefore it is unlikely that the sound waves propagate in the vehicle width direction and are directly received by the other sound wave sensors 2 b to 2 d .

[0100] However, for example, if both the acoustic wave sensor 2a and the acoustic wave sensor 2b are submerged, the directivity of the acoustic wave emitted from the acoustic wave sensor 2a is significantly reduced because the speed of sound in water is about 4.5 times the speed of sound in air. Figure 1 As shown, the sound wave S emitted from the sound wave sensor 2a propagates in the vehicle width direction and is directly received by the sound wave sensor 2b.

[0101] For example, when the acoustic wave sensor 2a and the acoustic wave sensor 2b are arranged at a distance of 75 cm, and the speed of sound in water is set to 1500 m / sec, the propagation time of the acoustic wave S from the acoustic wave sensor 2a to the acoustic wave sensor 2b is 0.5 msec.

[0102] Therefore, if Figure 5As shown, the control unit 21 shortens the time of shielding the reception in the receiving circuit 11 of the acoustic wave sensor 2b to 0.5 msec. Thus, when the acoustic wave S is received by the acoustic wave sensor 2b, the reception signal of the acoustic wave S is received by the receiving circuit 11 of the acoustic wave sensor 2b just after the shielding is released.

[0103] In this way, the phenomenon of receiving a relatively high intensity reception signal in a short time since the transmission of the sound wave is not a phenomenon that occurs only when moisture adheres to both the sound wave sensor 2a and the sound wave sensor 2b, but is a unique phenomenon that occurs only when both the sound wave sensor 2a and the sound wave sensor 2b are submerged.

[0104] Moreover, in step S6, after removing the shielding of reception, the control unit 21 calculates the propagation time from the emission of the sound wave S by the sound wave sensor 2a to the detection of the sound wave S by the sound wave sensor 2b, and based on the information of the propagation time, determines whether both the sound wave sensor 2a and the sound wave sensor 2b are submerged.

[0105] For example, when the propagation time is less than a predetermined threshold, the control unit 21 determines that both the acoustic wave sensor 2a and the acoustic wave sensor 2b are submerged. The predetermined threshold is set, for example, to a value smaller than a value obtained by dividing the distance between the acoustic wave sensor 2a and the acoustic wave sensor 2b by the speed of sound in air, and larger than a value obtained by dividing the distance between the acoustic wave sensor 2a and the acoustic wave sensor 2b by the speed of sound in water.

[0106] In this way, the control unit 21 determines whether the acoustic wave sensor 2a and the acoustic wave sensor 2b are submerged based on information on the propagation time of the acoustic wave S in the water from the acoustic wave sensor 2a to the acoustic wave sensor 2b, and thus can accurately determine whether the acoustic wave sensor 2a and the acoustic wave sensor 2b are submerged.

[0107] In addition, the control unit 21 shortens the time for shielding the reception of the sound wave sensor 2b based on the reverberation frequency, so that the sound wave S reaching the sound wave sensor 2b from the sound wave sensor 2a in a short time can be reliably received, and the submergence determination can be performed with higher accuracy.

[0108] In addition, the control unit 21 may also release the shielding of the reception of the acoustic wave sensor 2b during the entire transmission period of the acoustic wave sensor 2a. That is, the control unit 21 may control the acoustic wave sensor 2b to receive the acoustic wave at the beginning of the transmission period of the acoustic wave sensor 2a.

[0109] In addition, the control unit 21 may also shorten the shielding time based on reverberation characteristics other than the reverberation frequency. For example, the duration of reverberation varies greatly depending on whether moisture is attached to the piezoelectric element 9. Therefore, the control unit 21 may shorten the shielding time of the received signal of the acoustic wave sensor 2b based on the duration of reverberation.

[0110] When it is determined in step S6 that both the acoustic wave sensor 2a and the acoustic wave sensor 2b are not submerged, the process of step S1 is executed again, and the acoustic wave sensors 2a~2d that emit sound waves are changed in sequence and the processes of step S1~step S6 are repeated until it is determined that both the acoustic wave sensor 2a and the acoustic wave sensor 2b are submerged.

[0111] On the other hand, when it is determined in step S6 that both the acoustic wave sensor 2a and the acoustic wave sensor 2b are submerged, the process proceeds to step S7, and the control unit 21 controls the output device 6 to inform the occupants of the vehicle 1 of the danger of the vehicle 1 being submerged.

[0112] Generally speaking, the acoustic wave sensors 2a~2d for obstacle detection are arranged at a lower side than the driving parts such as the engine. Therefore, they can inform the occupants of the danger of flooding before the driving parts stop due to immersion in water due to road flooding, etc., and enable the occupants to take appropriate countermeasures such as avoiding flooding.

[0113] In addition, the driver's vision is poor in the rain, so it is difficult for the driver to determine which part of the vehicle 1 is submerged in water. At this time, by notifying the danger of submergence of the vehicle 1 through the control unit 21, the driver can take measures such as changing the direction of the vehicle 1 to avoid the danger of submergence.

[0114] Alternatively, the control unit 21 may repeatedly perform steps S1 to S7 for multiple times, and change the notification method of the output device 6 based on the result of the determination, i.e., whether both the acoustic wave sensor 2a and the acoustic wave sensor 2b have been submerged a specified number of times or less.

[0115] For example, when the control unit 21 determines that the number of submersions has reached a specified number of times, the control unit 21 may increase the intensity of the danger notification by notifying the occupants through both the display and the speaker, while when the number of submersions has not reached the specified number of times, the control unit 21 may only notify the occupants through the display to reduce the intensity of the danger notification.

[0116] In this way, the control unit 21 changes the notification method according to the number of times the submergence is determined, and can provide notification corresponding to the degree of risk of submergence to the occupant.

[0117] Alternatively, when the control unit 21 determines in step S6 that at least the acoustic wave sensor 2 a and the acoustic wave sensor 2 b are submerged, the control unit 21 may control the driving unit and the braking unit of the vehicle 1 via the driving system ECU 4 and the braking system ECU 5 .

[0118] For example, when the control unit 21 determines that at least the acoustic wave sensor 2 a and the acoustic wave sensor 2 b are submerged, the control unit 21 may control the driving system ECU 4 and the braking system ECU 5 to reduce the speed of the vehicle 1 .

[0119] Furthermore, when the control unit 21 determines that at least the acoustic wave sensors 2 a and 2 b are submerged, the control unit 21 may control the driving system ECU 4 and the braking system ECU 5 so as to invalidate the travel restriction based on the obstacle detection of the vehicle 1 .

[0120] For example, when control such as acceleration limitation by the drive system ECU 4 and forced braking by the brake system ECU 5 is executed based on obstacle detection, the control unit 21 performs control so as to invalidate such control and not perform acceleration limitation and forced braking.

[0121] At this time, the control unit 21 preferably controls the output device 6 to notify the occupant that the driving restriction based on the obstacle detection of the vehicle 1 has been invalidated.

[0122] According to this embodiment, the control unit 21 determines whether both the sound wave sensor 2a and the sound wave sensor 2b are submerged based on the information of the propagation time of the sound wave S from the emission of the sound wave S by the sound wave sensor 2a to the detection of the sound wave S by the sound wave sensor 2b, thereby being able to make a high-precision determination of submergence.

[0123] In addition, in the present embodiment, the processing of step S2, step S3, and step S5 for shortening the time for masking reception based on the reverberation characteristics may be eliminated.

[0124] (Implementation Method 2)

[0125] In the above-mentioned first embodiment, when the control unit 21 determines that at least two acoustic wave sensors are submerged, the control unit 21 may control the obstacle detection device 18 to detect an obstacle using a method suitable for underwater detection.

[0126] For example, Figure 6 As shown, the control unit 21 can switch the mode set for the obstacle detection device 18 between the flooding mode and the normal mode.

[0127] First, similarly to the first embodiment, steps S1 and S2 are performed, and in step S3, the control unit 21 determines whether the reverberation frequency is less than a predetermined threshold value Th. When the control unit 21 determines that the reverberation frequency is greater than the predetermined threshold value Th, the control unit 21 proceeds to step S21 and sets the shielding period of the acoustic wave sensors 2a to 2d to a normal shielding period. That is, the control unit 21 controls the receiving signals of the acoustic wave sensors 2a to 2d to be shielded during the entire transmission period of the acoustic wave sensor 2a that transmits the acoustic wave.

[0128] Next, the control unit 21 sets the obstacle detection device 18 to the normal mode in step S22. Here, the normal mode refers to a mode set to be suitable for detecting obstacles in the air. For example, in the normal mode, the transmission period of the sound wave, the transmission power of the sound wave, the threshold value of the intensity of the received sound wave for determining the obstacle, the speed of sound in the air for calculating the distance between the obstacle and the vehicle 1, etc. can be set. As a result, the obstacle detection device 18 can detect obstacles through the settings suitable for detection in the air, and can reliably detect obstacles.

[0129] On the other hand, when it is determined in step S3 that the reverberation frequency is less than the predetermined threshold value Th, the control unit 21 executes steps S5 and S6 in the same manner as in Embodiment 1. At this time, when it is determined in step S6 that both the acoustic wave sensor 2a and the acoustic wave sensor 2b are not submerged, the process proceeds to step S22, and the control unit 21 sets the obstacle detection device 18 to the normal mode.

[0130] In addition, when it is determined in step S6 that both the acoustic wave sensor 2a and the acoustic wave sensor 2b are submerged, the process proceeds to step S7 as in embodiment 1, and the control unit 21 controls the output device 6 to inform the occupants of the vehicle 1 of the danger of the vehicle 1 being submerged.

[0131] Next, the control unit 21 sets the obstacle detection device 18 to the submerged mode in step S23. Here, the submerged mode refers to a mode set to a mode suitable for detecting an obstacle in water.

[0132] For example, the control unit 21 may change the setting of the obstacle detection device 18 so that the emission period of the sound waves emitted from at least the two sound wave sensors 2a and 2b is shorter than that in the normal mode. Generally speaking, the speed of sound in water is faster than that in air, so that obstacles at a farther distance can be detected in a shorter time than in air. Therefore, the control unit 21 changes the setting of the obstacle detection device 18 so that the emission period of the sound waves is shorter than that in the case of emitting the sound waves in the air, and starts receiving the sound waves earlier. As a result, obstacles at a closer distance can also be detected.

[0133] In addition, the control unit 21 can change the setting of the obstacle detection device 18 to adjust the transmission power of the sound waves emitted from at least the two sound wave sensors 2a and 2b. Generally speaking, the transmission efficiency of sound waves in water is higher than that in air, and the attenuation rate of sound waves in water is lower than that in air, so that sound waves propagate farther in water than in air. Therefore, the control unit 21 can change the setting of the obstacle detection device 18 to reduce the transmission power of at least the two sound wave sensors 2a and 2b.

[0134] The control unit 21 may change the setting of the obstacle detection device 18 so as to calculate the distance between the obstacle outside the vehicle 1 and the acoustic wave sensors 2a to 2h based on the speed of sound in water. This allows detection of underwater obstacles with higher accuracy.

[0135] Furthermore, the control unit 21 may change the setting of the obstacle detection device 18 to change the threshold of the intensity value in the intensity waveform of the received sound wave used by the determination circuit 15 to determine an obstacle outside the vehicle 1. Since the attenuation rate of sound waves in water is lower than that in air, for example, the control unit 21 may change the threshold in the submerged mode to a threshold value in which the intensity value decreases more gradually than in the normal mode in which the intensity value decreases as the propagation time (propagation distance) of the sound wave increases.

[0136] According to this embodiment, when it is determined that at least two acoustic wave sensors 2a and 2b are submerged, the control unit 21 changes the setting of the obstacle detection device 18 to a submerged mode corresponding to detection of underwater obstacles, thereby enabling reliable detection of underwater obstacles.

[0137] (Implementation 3)

[0138] In the above-mentioned embodiments 1 and 2, the control unit 21 can either determine the noise level detected by the acoustic wave sensors 2a~2d and, based on the noise level, release the shielding of reception in the acoustic wave sensors 2b~2d that receive the acoustic waves emitted from the acoustic wave sensor 2a, or the control unit 21 can shorten the time for shielding the reception.

[0139] For example, Figure 7 As shown, the control unit 21 sets a noise monitoring period before the sound wave sensor 2a emits sound waves, and determines the noise level during the noise monitoring period.

[0140] First, the receiving circuits 11 of the acoustic wave sensors 2 a to 2 d receive acoustic wave signals during a noise monitoring period set before a transmission period during which acoustic waves are transmitted from the acoustic wave sensor 2 a , and output the received signals to the determination circuit 15 .

[0141] The determination circuit 15 detects the noise level contained in the received signal when receiving the received signal from the receiving circuit 11. For example, if the vehicle 1 is traveling on a flooded road, the sound waves generated by splashing water or the like are received, and thus the intensity of the sound waves can be detected as the noise level. The determination circuit 15 outputs the detected noise level to the sonar ECU 3.

[0142] The sonar ECU 3 inputs the noise level detected by the determination circuit 15 to the control unit 21 via the acquisition unit 20 of the submergence detection device 19. When the noise level detected by the determination circuit 15 is input from the acquisition unit 20, the control unit 21 determines whether the noise level exceeds a predetermined level.

[0143] When the noise level does not exceed a predetermined level, the control unit 21 drives the acoustic wave sensor 2a to emit acoustic waves without changing the settings of the shielding of the acoustic wave sensors 2b to 2d.

[0144] On the other hand, in the case where the noise level exceeds the prescribed level, e.g. Figure 7 As shown, the control unit 21 controls the receiving circuits 11 of the acoustic wave sensors 2b to 2d to release the shielding of reception during the transmission period of the acoustic wave, and then drives the acoustic wave sensor 2a to transmit the acoustic wave.

[0145] Furthermore, when the noise level exceeds a predetermined level, the control unit 21 may control the receiving circuits 11 of the acoustic wave sensors 2b to 2d so as to shorten the time for shielding the reception during the transmission of the acoustic wave.

[0146] Then, similarly to the first embodiment, the control unit 21 determines whether both the sonic wave sensor 2a and the sonic wave sensor 2b are submerged based on the information of the propagation time from when the sonic wave sensor 2a emits the sonic wave S to when the sonic wave sensor 2b detects the sonic wave S.

[0147] Thus, the control unit 21 releases the shielding of the reception of the acoustic wave sensors 2b to 2d based on the noise level, so that, for example, the acoustic wave S emitted from the acoustic wave sensor 2a and directly received by the acoustic wave sensor 2b can be reliably received, and the submergence determination can be performed with higher accuracy.

[0148] Furthermore, the control unit 21 may determine whether to release the reception masking based on only the noise level, or may determine whether to release the reception masking based on both the noise level and the reverberation characteristics of the first embodiment.

[0149] According to this embodiment, the control unit 21 cancels the reception shielding of the sound wave sensors 2b to 2d based on the noise level, so that the sound wave S emitted from the sound wave sensor 2a and directly received by the sound wave sensor 2b can be reliably received, and the submergence determination can be performed with higher accuracy.

[0150] In the above-mentioned embodiments 1 to 3, the acoustic wave sensors 2a to 2h are used by both the submergence detection device 19 and the obstacle detection device 18 , but an acoustic wave sensor different from the acoustic wave sensor of the obstacle detection device 18 may be used as a dedicated acoustic wave sensor for the submergence detection device 19 .

[0151] In addition, in the above-mentioned Embodiments 1 to 3, all the acoustic wave sensors 2a to 2h are not necessarily arranged at the same height, and may be arranged at different heights.

[0152] As mentioned above, although embodiment of this invention is described in detail with reference to drawings, the function of each said apparatus can also be implemented by a computer program.

[0153] The reading device of the computer that realizes the functions of the above-mentioned devices through the program reads the program from the recording medium storing the program for realizing the functions of the above-mentioned devices and stores it in the storage device. Alternatively, the network card communicates with the server device connected to the network and stores the program for realizing the functions of the above-mentioned devices downloaded from the server device in the storage device.

[0154] Furthermore, the CPU (Central Processing Unit) copies the program stored in the storage device to the RAM (Random Access Memory), and sequentially reads and executes the commands included in the program from the RAM, thereby realizing the functions of the above-mentioned devices.

[0155] Industrial Applicability

[0156] The submergence detection device of the present invention can be applied to a device for detecting submergence of at least two acoustic wave sensors mounted on a vehicle.

Claims

1. A flooding detection device, characterized in that: The submergence detection device detects submergence of at least two acoustic wave sensors mounted on a vehicle and comprises: an acquisition unit that acquires information on a time from when the first acoustic wave sensor transmits the acoustic wave to when the second acoustic wave sensor detects the acoustic wave transmitted from the first acoustic wave sensor; and The control unit determines whether both the first acoustic wave sensor and the second acoustic wave sensor are submerged based on the time information, In which, the control unit determines whether the noise level detected by the first sound wave sensor or the second sound wave sensor exceeds a specified level. If the noise level exceeds the specified level, the control unit releases the shielding of the reception during the transmission period of the sound wave, or shortens the time for shielding the reception during the transmission period of the sound wave.

2. The flooding detection device according to claim 1, wherein: The control unit determines that both the first sonic wave sensor and the second sonic wave sensor are submerged when the time is less than a prescribed threshold value, and the prescribed threshold value is set to a value smaller than a value obtained by dividing the distance between the first sonic wave sensor and the second sonic wave sensor by the speed of sound in air, and larger than a value obtained by dividing the distance between the first sonic wave sensor and the second sonic wave sensor by the speed of sound in water.

3. The flooding detection device according to claim 1, wherein: The control unit controls the at least two acoustic wave sensors to shorten a transmission period of the acoustic wave when it is determined that both the first acoustic wave sensor and the second acoustic wave sensor are submerged.

4. The flooding detection device according to claim 1, wherein: The control unit calculates a distance between an obstacle outside the vehicle and the vehicle based on a speed of sound in water when it is determined that both the first acoustic wave sensor and the second acoustic wave sensor are submerged.

5. The flooding detection device according to claim 1, wherein: The control unit controls the at least two acoustic wave sensors to adjust the transmission power of the acoustic wave when it is determined that both the first acoustic wave sensor and the second acoustic wave sensor are submerged.

6. The flooding detection device according to claim 1, wherein: The control unit changes a threshold value of the intensity of received sound waves for determining an obstacle outside the vehicle when it is determined that both the first sound wave sensor and the second sound wave sensor are submerged.

7. The flooding detection device according to claim 1, wherein: The control unit performs control to notify a passenger of the vehicle that the vehicle is in danger of being submerged, when it is determined that both the first acoustic wave sensor and the second acoustic wave sensor are submerged.

8. The flooding detection device according to claim 7, wherein: The control unit performs the determination a plurality of times and changes the notification method according to the determination result, that is, whether the number of times both the first acoustic wave sensor and the second acoustic wave sensor have been submerged has reached a prescribed number of times or has not reached the prescribed number of times.

9. The flooding detection device according to claim 1, wherein: The control unit reduces the speed of the vehicle when it is determined that the at least two acoustic wave sensors are submerged.

10. A flooding detection device according to any one of claims 1 to 9, The control unit invalidates the driving restriction based on obstacle detection of the vehicle when it is determined that the at least two acoustic wave sensors are submerged.

11. A flooding detection device, characterized in that: The submergence detection device detects submergence of at least two acoustic wave sensors mounted on a vehicle and comprises: an acquisition unit that acquires information on a time from when the first acoustic wave sensor transmits the acoustic wave to when the second acoustic wave sensor detects the acoustic wave transmitted from the first acoustic wave sensor; and The control unit determines whether both the first acoustic wave sensor and the second acoustic wave sensor are submerged based on the time information, Among them, the control unit determines whether the reverberation frequency of the sound wave is lower than the specified frequency. If the reverberation frequency of the sound wave is lower than the specified frequency, the shielding of the reception during the transmission period of the sound wave is released, or the time of shielding the reception during the transmission period of the sound wave is shortened.

12. The flooding detection device according to claim 11, The control unit invalidates the driving restriction based on obstacle detection of the vehicle when it is determined that the at least two acoustic wave sensors are submerged.

13. The flooding detection device according to claim 12, wherein: The control unit performs control to notify a passenger of the vehicle that a travel restriction based on obstacle detection of the vehicle has been invalidated.

14. A vehicle, characterized in that: The vehicle has at least two acoustic sensors and has: The submergence detection device according to any one of claims 1 to 13; and An output device informs occupants of the vehicle of the risk of submersion of the vehicle.

15. A flooding detection method, characterized in that: The submergence detection method is a submergence detection method for detecting submergence of at least two acoustic wave sensors mounted on a vehicle, and comprises the following steps: a step of determining whether the noise level detected by the first sound wave sensor or the second sound wave sensor exceeds a prescribed level; When the noise level exceeds a predetermined level, the step of releasing the shielding of reception during the transmission of the sound wave or shortening the time for shielding the reception during the transmission of the sound wave; a step of acquiring information on the time from when the first acoustic wave sensor transmits the acoustic wave to when the second acoustic wave sensor detects the acoustic wave transmitted from the first acoustic wave sensor; and Based on the time information, a step of determining whether both the first acoustic wave sensor and the second acoustic wave sensor are submerged is performed.

16. A flooding detection method, characterized in that: The submergence detection method is a submergence detection method for detecting submergence of at least two acoustic wave sensors mounted on a vehicle, and comprises the following steps: The step of determining whether the reverberation frequency of the sound wave is lower than a specified frequency; A step of releasing the shielding of reception during the transmission period of the sound wave, or shortening the time for shielding reception during the transmission period of the sound wave, when the reverberation frequency of the sound wave is lower than the specified frequency; a step of acquiring information of a time until the sound wave emitted from the first sound wave sensor is detected by the second sound wave sensor; and Based on the time information, a step of determining whether both the first acoustic wave sensor and the second acoustic wave sensor are submerged is performed.

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