Object detection device

Abstract

An object detection device of the present invention comprises: an acquisition unit (301) that acquires detected distances indicating distances from a transmission / reception unit to objects, the distances being detected on the basis of the result of the transmission of transmission waves by a transmission / reception unit (21) mounted on a vehicle (1) and the reception of reflected waves from the objects by the transmission / reception unit, and reception intensities indicating the intensities of the reflected waves received by the transmission / reception unit; and a detection unit (302) that detects a detection target among the objects on the basis of the reception intensities exceeding an intensity threshold (L2). The detection unit (302) increases the intensity threshold (L21) when the detected distance is less than or equal to a distance threshold and the detection target is detected.

Description

[Technical field]

[0001] The present disclosure relates to an object detection device. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there is known an object detection device that detects a detection target among objects present around a vehicle based on the results of transmission and reception of ultrasonic waves by an ultrasonic sensor mounted on the vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6519115 Summary of the Invention [Problem to be solved by the invention]

[0004] In this type of object detection device, it would be beneficial if the detection accuracy of the detection target could be improved.

[0005] One of the problems that the present disclosure aims to solve is to improve the detection accuracy of an object detection device. [Means for solving the problem]

[0006] An object detection device as an example of the present disclosure includes an acquisition unit that acquires a detection distance indicating the distance from the transceiver unit to the object, detected based on the result of transmitting a transmission wave by the transceiver unit mounted on a vehicle and receiving a reflected wave from the object by the transceiver unit, and a reception intensity indicating the intensity of the reflected wave received by the transceiver unit, and a detection unit that detects a detection target among the objects based on the reception intensity exceeding an intensity threshold, and when the detection distance is equal to or less than the distance threshold and the detection unit detects the detection target, the detection unit increases the intensity threshold.

[0007] According to such a configuration, for example, when the detection distance is equal to or less than the distance threshold and the detection target is detected, the intensity threshold becomes high, so that the detection unit is prevented from erroneously detecting an object other than the detection target as the detection target (false detection), thereby improving the detection accuracy of the object detection device.

[0008] In the object detection device, for example, the detection unit increases the intensity threshold when the detection distance is equal to or less than the distance threshold and, after the number of times the detection target is detected is added, the number of times the detection target is detected becomes equal to or greater than the number threshold.

[0009] According to such a configuration, for example, when the detection distance is equal to or less than the distance threshold and the number of detections of the detection target is added, and the number of detections of the detection target is equal to or more than the number of detections threshold, the intensity threshold becomes high, so that the detection unit is prevented from erroneously detecting an object other than the detection target as the detection target (false detection). Thus, the detection accuracy of the object detection device for the detection target can be improved.

[0010] In the object detection device, for example, the distance threshold is greater than an installation height indicating a height of the transmitter / receiver from a road surface.

[0011] According to this configuration, it is possible to detect a detection target that is present at least around the vehicle and within an installation height of the transceiver unit from the transceiver unit. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a top view showing an example of the configuration of a vehicle according to an embodiment. [Diagram 2] FIG. 2 is a block diagram showing an example of the configuration of the vehicle control device according to the embodiment. [Diagram 3] FIG. 3 is a block diagram illustrating an example of a functional configuration of the object detection device according to the embodiment. [Figure 4] FIG. 4 is a diagram showing an envelope for explaining an outline of an object detection method using TOF in the embodiment. [Diagram 5]FIG. 5 is a flowchart illustrating an example of an object detection process executed by the object detection device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The configurations of the embodiments described below and the actions and effects brought about by the configurations are merely examples, and the present invention is not limited to the following description.

[0014] 1 is a top view showing an example of the configuration of a vehicle 1 according to an embodiment. The vehicle 1 is an example of a vehicle (mobile body) on which an object detection device according to the embodiment is mounted. The object detection device according to the embodiment is a device that detects objects (other vehicles, structures, pedestrians, etc.) present around the vehicle 1 based on TOF (Time Of Flight), Doppler shift information, etc. acquired by transmitting ultrasonic waves from the vehicle 1 and receiving reflected waves from the objects.

[0015] The object detection device according to this embodiment has a plurality of transceivers 21A to 21H (hereinafter, abbreviated to transceivers 21 when there is no need to distinguish between the plurality of transceivers 21A to 21H). Each transceiver 21 is installed on a vehicle body 2 serving as the exterior of a vehicle 1, transmits ultrasonic waves (transmission waves) toward the outside of the vehicle body 2, and receives reflected waves from objects present outside the vehicle body 2. In the example shown in FIG. 1, four transceivers 21A to 21D are arranged at the front end of the vehicle body 2, and four transceivers 21E to 21H are arranged at the rear end. Note that the number and installation positions of the transceivers 21 are not limited to the above example.

[0016] 2 is a block diagram showing an example of a configuration of a vehicle control device 50 according to an embodiment. The vehicle control device 50 performs processing for controlling the vehicle 1 based on information output from the object detection device 200. The vehicle control device 50 according to the present embodiment includes an ECU 100 and the object detection device 200.

[0017] The object detection device 200 includes a plurality of transmitting / receiving units 21 and a control unit 22. Each transmitting / receiving unit 21 includes an oscillator 211 configured using a piezoelectric element or the like, an amplifier, etc., and realizes transmission and reception of ultrasonic waves by the vibration of the oscillator 211. Specifically, each transmitting / receiving unit 21 transmits ultrasonic waves generated in response to the vibration of the oscillator 211 as a transmission wave, and detects the vibration of the oscillator 211 caused by a reflected wave of the transmission wave reflected by the object O. The vibration of the oscillator 211 is converted into an electric signal, and based on the electric signal, it is possible to obtain a TOF corresponding to the distance from the transmitting / receiving unit 21 to the object O, Doppler shift information corresponding to the relative speed of the object O, etc.

[0018] The transceiver 21 according to this embodiment transmits a transmission wave including ultrasonic waves having directivity in a direction parallel or approximately parallel to the traveling direction of the vehicle 1. The transmission wave includes ultrasonic waves (non-directional components) traveling vertically downward from the transceiver 21.

[0019] 2, a configuration is illustrated in which both transmission of the transmission wave and reception of the reflected wave are performed using a single transducer 211, but the configuration of the transceiver unit 21 is not limited to this. For example, a configuration in which the transmission side and the reception side are separated, such as a configuration in which a transducer for transmitting the transmission wave and a transducer for receiving the reflected wave are separately provided, may also be used.

[0020] The control unit 220 includes an input / output device 221, a storage device 222, and a processor 223. The input / output device 221 is an interface device for transmitting and receiving information between the control unit 220 and the outside (the transmission / reception unit 21, the ECU 100, etc.). The storage device 222 includes a main storage device such as a Read Only Memory (ROM) or a Random Access Memory (RAM), and an auxiliary storage device such as a Hard Disk Drive (HDD) or a Solid State Drive (SSD). The processor 223 is an integrated circuit that executes various processes for implementing the functions of the control unit 220, and may be, for example, a Central Processing Unit (CPU) that operates according to a program, a memory for a specific purpose, or the like. The processor 223 reads and executes the programs stored in the storage device 222 to perform various types of arithmetic processing and control processing.

[0021] The ECU 100 is a unit that executes various processes for controlling the vehicle 1 based on various information acquired from the object detection device 200 and the like. The ECU 100 has an input / output device 110, a storage device 120, and a processor 130. The input / output device 110 is an interface device for realizing transmission and reception of information between the ECU 100 and external mechanisms (the object detection device 200, a drive mechanism, a braking mechanism, a steering mechanism, a transmission mechanism, an in-vehicle display, a speaker, and the like). The storage device 120 includes a main storage device such as a ROM or a RAM, and an auxiliary storage device such as a HDD or an SSD. The processor 130 is an integrated circuit that executes various processes for realizing the functions of the ECU 100, and includes, for example, a CPU, an ASIC, and the like. The processor 130 reads out a program stored in the storage device 120 and executes various arithmetic processes and control processes.

[0022] Fig. 3 is a block diagram showing an example of a functional configuration of the object detection device 200 according to the embodiment. The object detection device 200 according to the present embodiment includes an acquisition unit 301 and a detection unit 302. These functional components 301 and 302 are realized by cooperation between the hardware components of the object detection device 200 shown in Fig. 2 and software components such as firmware and programs.

[0023] The acquisition unit 301 acquires various information. For example, the acquisition unit 301 processes data acquired by the transmission / reception unit 21 to generate various information. For example, the acquisition unit 301 performs amplification, filtering, line processing, etc. on an electric signal corresponding to the vibration of the transducer 211 to generate echo information indicating a change over time in the intensity (amplitude value) of a reflected wave transmitted by the transmission / reception unit 21 and reflected by an object O. The intensity of the reflected wave is the intensity of the reflected wave received by the transmission / reception unit 21. The amplitude value of the reflected wave is an example of the intensity of the reflected wave. The intensity of the reflected wave received by the transmission / reception unit 21 is also referred to as the reception intensity. Based on the echo information, the acquisition unit 301 detects a TOF corresponding to an object O present in the vicinity of the vehicle 1, and calculates, i.e., acquires, a detection distance, which is the distance from the transmission / reception unit 21 (vehicle body 2) to the object O.

[0024] Fig. 4 is a diagram showing an envelope for explaining an outline of an object detection method using TOF in an embodiment. Fig. 4 illustrates an envelope as echo information showing a change over time in the intensity of ultrasonic waves transmitted and received by the transmitting and receiving unit 21. In the graph shown in Fig. 4, the horizontal axis corresponds to time (TOF), and the vertical axis corresponds to the intensity of ultrasonic waves transmitted and received by the transmitting and receiving unit 21.

[0025] A solid line L11 shows an example of an envelope curve indicating a change over time in the strength indicating the magnitude of vibration of the oscillator 211. From this solid line L11, it can be seen that the oscillator 211 is driven to vibrate for a time Ta from timing t0, and the transmission of the transmission wave is completed at timing t1, and then the vibration of the oscillator 211 due to inertia continues while attenuating for a time Tb until timing t2. Therefore, in the graph shown in FIG. 4, the time Tb corresponds to the so-called reverberation time.

[0026] The solid line L11 indicates that the magnitude of vibration of the transducer 211 reaches a peak at a time t4, which is a time Tp after the timing t0 when the transmission of the transmission wave starts, and exceeds (or is equal to or exceeds) a predetermined intensity threshold (threshold) represented by the dashed-dotted line L21. This intensity threshold is a value that is set in advance to distinguish whether the vibration of the transducer 211 is caused by reception of a reflected wave from an object to be detected, or by reception of a reflected wave from an object that is not to be detected. Here, the intensity threshold represented by the dashed-dotted line L21 is shown as a constant value, but the intensity threshold is a variable value that changes, as will be described in detail later. The intensity threshold is also referred to as an amplitude threshold. The detection object is also referred to as an obstacle.

[0027] Vibrations having a peak that exceeds (or is equal to or greater than) the intensity threshold indicated by the dashed dotted line L21 can be considered to have been caused by reception of a reflected wave from an object O to be detected. On the other hand, vibrations having a peak that is equal to or less than (or less than) the intensity threshold can be considered to have been caused by reception of a reflected wave from an object O that is not to be detected. Therefore, it can be seen from the solid line L11 that the vibration of the transducer 211 at the timing t4 is caused by reception of a reflected wave from the object O to be detected.

[0028] In the solid line L11, the vibration of the transducer 211 attenuates after the timing t4. Therefore, the timing t4 corresponds to the timing at which the reception of the reflected wave from the object O to be detected is completed, in other words, the timing at which the transmission wave finally transmitted at the timing t1 returns as a reflected wave.

[0029] In addition, in the solid line L11, the timing t3 as the start point of the peak at the timing t4 corresponds to the timing when the reception of the reflected wave from the detection target object O starts, in other words, the timing when the transmission wave first transmitted at the timing t0 returns as a reflected wave. Therefore, the time ΔT between the timing t3 and the timing t4 is equal to the time Ta as the transmission time of the transmission wave.

[0030] Based on the above, in order to use TOF to find the distance to an object O, it is necessary to find the time Tf between the timing t0 when the transmitted wave starts to be transmitted and the timing t3 when the reflected wave starts to be received. This time Tf can be found by subtracting the time ΔT, which is equal to the time Ta for transmitting the transmitted wave, from the time Tp, which is the difference between the timing t0 and the timing t4 when the intensity of the reflected wave reaches a peak by exceeding a threshold.

[0031] The timing t0 when the transmission wave starts to be transmitted can be easily identified as the timing when the object detection device 200 starts to operate, and the time Ta as the transmission time of the transmission wave is determined in advance by settings, etc. Therefore, the distance to the object O to be detected can be obtained by identifying the timing t4 when the intensity of the reflected wave exceeds the threshold and reaches a peak.

[0032] As described above, the acquisition unit 301 acquires a detection distance indicating the distance from the transceiver unit 21 to the object O, which is detected based on the result of repeated transmission of a transmission wave by the transceiver unit 21 mounted on the vehicle 1 and reception of a reflected wave from the object O by the transceiver unit 21. The acquisition unit 301 also acquires a reception intensity indicating the intensity of the reflected wave received by the transceiver unit 21. The above detection distance and reception intensity constitute transmission and reception information. In other words, the transmission and reception information includes the detection distance and reception intensity.

[0033] The detection unit 302 detects the object O to be detected based on the reception intensity exceeding the intensity threshold. When the detection distance is equal to or less than the distance threshold and the detection target is detected, the detection unit 302 increases the intensity threshold. For example, when the detection distance is equal to or less than the distance threshold and the number of times the detection target is detected (hereinafter also referred to as the number of times of detection) is equal to or more than the number of times threshold, the detection unit 302 increases the intensity threshold. For example, when the detection distance is equal to or less than the distance threshold and the number of times the detection target is detected is equal to or more than the number of times threshold after the number of times of detection of the detection target is added, the detection unit 302 increases the intensity threshold. That is, when the number of times the object O is detected within a predetermined distance from the transmission / reception unit 21 exceeds a predetermined number of times, the detection unit 302 increases the intensity threshold. In this way, the detection unit 302 dynamically corrects the intensity threshold. For example, there are two values ​​for the intensity threshold, and the two values ​​are alternatively selected. The two values ​​are a small threshold and a large threshold. The small threshold is smaller than the large threshold. In other words, the large threshold is larger than the small threshold. The small threshold and the large threshold may each have a preset value. In addition, one of the small threshold and the large threshold may be set as a reference, and the other may be determined as a ratio to the reference. For example, when the large threshold is the reference, the small threshold is set to a predetermined ratio to the large threshold. As an example, the small threshold is 60% of the large threshold. Note that the ratio of the small threshold to the large threshold may be other than 60%. The distance threshold is, for example, a fixed value set in advance. As an example, the distance threshold is greater than the installation height indicating the height of the transceiver 21 from the road surface G. The installation height indicates the height of the transceiver 21 from the road surface G in the vehicle 1 in a predetermined state, and is a fixed value set in advance. The vehicle 1 in the predetermined state may be, for example, a state in which no occupant is on board, or a state in which the maximum number of occupants are on board. Note that the intensity threshold and the distance threshold are not limited to the above.

[0034] Next, an object detection process (object detection method) performed by the object detection device 200 will be described with reference to Fig. 5. Fig. 5 is a flowchart showing an example of the object detection process performed by the object detection device 200 according to the embodiment.

[0035] 5, the detection unit 302 sets the intensity threshold to a small threshold (S101), and the transmission / reception unit 21 then transmits a signal and receives a reflected wave.

[0036] Next, the acquisition unit 301 acquires transmission and reception information based on the transmission of the transmission wave and the reception of the reflected wave by the transmission and reception unit 21 from the transmission and reception unit 21 (S102). As described above, the transmission and reception information includes the detection distance and the reception intensity.

[0037] Next, the detection unit 302 determines whether or not a detection target (confirmed candidate) has been detected among the object O based on the reception strength of the transmitted and received information (S103). Here, the detection unit 302 detects the object O whose reception strength exceeds the intensity threshold as the detection target. Therefore, when the reception strength exceeds the intensity threshold, the detection unit 302 determines that the detection target has been detected (S103: Yes), and proceeds to S104. On the other hand, when the reception strength is equal to or less than the intensity threshold, the detection unit 302 determines that the detection target has not been detected (S103: No), and proceeds to S109.

[0038] In S104, the detection unit 302 determines whether the detection distance included in the transmission / reception information is equal to or less than the distance threshold. If the detection unit 302 determines that the detection distance included in the transmission / reception information is equal to or less than the distance threshold (S104: Yes), the process proceeds to S105. On the other hand, if the detection unit 302 determines that the detection distance included in the transmission / reception information is not equal to or less than the distance threshold, that is, the detection distance included in the transmission / reception information is greater than the distance threshold (S104: No), the process proceeds to S109.

[0039] In S105, the detection unit 302 increments the number of detections by one in a counter area provided in the storage device 120. Here, the counter area provided in the storage device 120 is an area for storing the number of times the detection target is detected (hereinafter also referred to as the detection number). The counter area is also referred to as a number storage unit.

[0040] Next, the detection unit 302 determines whether the detection count stored in the counter area is equal to or greater than the count threshold (S106). Here, the count threshold is, for example, a fixed value, and is, for example, two times. The count threshold may be a value other than two times. If the detection unit 302 determines that the detection count stored in the counter area is equal to or greater than the count threshold (S106: Yes), the process proceeds to S107. On the other hand, if the detection unit 302 determines that the detection count stored in the counter area is not equal to or greater than the count threshold, that is, the detection count stored in the counter area is less than the count threshold (S106: No), the process proceeds to S110.

[0041] In S107, the detection unit 302 sets the intensity threshold to the large threshold. After that, the detection unit 302 proceeds to S108.

[0042] In S108, the detection unit 302 performs a detection target determination process. Specifically, the detection unit 302 determines whether the detection count stored in the counter area is equal to or greater than the confirmation threshold. The confirmation threshold is a threshold greater than the count threshold, and is, for example, three times. The confirmation threshold may be a value other than three times. When the detection unit 302 determines that the detection count stored in the counter area is equal to or greater than the confirmation threshold, it determines that the object O is a detection target. On the other hand, when the detection unit 302 determines that the detection count stored in the counter area is not equal to or greater than the confirmation threshold, that is, the detection count stored in the counter area is less than the confirmation threshold, it does not determine that the object O is a detection target. It is to be noted that the method of determining whether the object O is a detection target (determination method) is not limited to the above.

[0043] When the detection unit 302 determines that the object O is a detection target, it transmits determination information indicating that the object O is a detection target to the ECU 100. When the ECU 100 receives the determination information, it executes a predetermined process. The predetermined process is an alarm process for issuing an alarm via an in-vehicle display or speaker, a braking process for braking the vehicle 1 using a braking mechanism, etc.

[0044] In S109, the detection unit 302 resets the number of detections stored in the counter area. That is, the detection unit 302 sets the number of detections stored in the counter area to zero.

[0045] Furthermore, in S110, the detection unit 302 sets the intensity threshold to a small threshold.

[0046] As described above, when the detection distance is equal to or less than the distance threshold (S104: Yes) and the number of times the detection target has been detected is equal to or greater than the number of times threshold (S106: Yes), the detection unit 302 increases the intensity threshold.

[0047] Furthermore, if the detection target is not detected (S103: No) or if the detection distance is not equal to or less than the distance threshold (S104: No), the detection unit 302 resets the detection count (S109), sets the intensity threshold to the small threshold (S110), and then performs the process of S108. In this case, since the detection count is reset, i.e., set to 0, in S108, the detection count stored in the counter area is not equal to or greater than the confirmation threshold. Therefore, in this case, the detection unit 302 does not confirm in S108 that object O is the detection target.

[0048] Furthermore, if the detection count is not equal to or greater than the count threshold (S106: No), the detection unit 302 sets the intensity threshold to the small threshold (S110) and then performs the process of S108. In this case, since the detection count is not equal to or greater than the count threshold, the detection count is not equal to or greater than the confirmation threshold. Therefore, in this case, the detection unit 302 does not confirm in S108 that object O is the detection target.

[0049] As described above, in this embodiment, the object detection device 200 includes an acquisition unit 301 and a detection unit 302. The acquisition unit 301 acquires a detection distance indicating the distance from the transceiver unit 21 to the object O, which is detected based on the results of repeated transmission of a transmission wave by the transceiver unit 21 mounted on the vehicle 1 and reception of a reflected wave from the object O by the transceiver unit 21, and a reception intensity indicating the intensity of the reflected wave received by the transceiver unit 21. The detection unit 302 detects a detection target among the object O based on a reception intensity exceeding an intensity threshold. The detection unit 302 increases the intensity threshold when the detection distance is equal to or less than the distance threshold and the number of times the detection target is detected is equal to or greater than the number of times threshold.

[0050] According to such a configuration, for example, when the detection distance is equal to or less than the distance threshold and the number of times the detection target is detected is equal to or greater than the number threshold, the intensity threshold becomes high, so that the detection unit 302 is prevented from erroneously detecting an object O other than the detection target as the detection target (misdetection). Therefore, the detection accuracy of the object detection device 200 for the detection target can be improved.

[0051] For example, when determining whether object O is the detection target, the intensity threshold is high, so that the detection unit 302 is prevented from erroneously detecting (falsely detecting) an object O other than the detection target as the detection target. Therefore, for example, the detection unit 302 is prevented from erroneously detecting a road surface G, which is not the detection target, as the detection target. Therefore, the occurrence of false alarms and malfunctions of the braking mechanism due to false detection is prevented.

[0052] Furthermore, according to the above configuration, when the detection distance is greater than the distance threshold, the intensity threshold is lowered. Therefore, even if the reflected wave is from an object O that is far away from the vehicle 1 and has weak reflection, the reflected wave is likely to exceed the threshold. Therefore, even if the object O is far away from the vehicle 1 and has weak reflection, the detection distance can be calculated.

[0053] Moreover, the distance threshold is greater than the installation height indicating the height of the transmitting / receiving unit 21 from the road surface G.

[0054] According to this configuration, it is possible to detect an object O to be detected that is present at least around the vehicle 1 and within the installation height of the transmitter-receiver unit 21.

[0055] The programs for causing a computer (for example, the processor 223 of the control unit 220, the processor 130 of the ECU 100, etc.) to execute processes for implementing the various functions in the above-described embodiment are stored on a CD (Compact Disc) in the form of installable or executable files. The program can be provided by recording it on a computer-readable recording medium such as a ROM, a flexible disk (FD), a CD-R (Recordable), a DVD (Digital Versatile Disk), etc. The program may also be provided or distributed via a network such as the Internet.

[0056] The detection unit 302 in the above embodiment is configured to increase the intensity threshold when the detection distance is equal to or less than the distance threshold and the number of times the detection target is detected is equal to or more than the number of times threshold, but is not limited to this. The detection unit 302 may be configured to increase the intensity threshold when the detection distance is equal to or less than the distance threshold and the number of times the detection target is detected is increased.

[0057] Although the embodiments of the present disclosure have been described above, the above-mentioned embodiments and their modifications are merely examples and are not intended to limit the scope of the invention. The above-mentioned novel embodiments and modifications can be implemented in various forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. The above-mentioned embodiments and modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0058] 1...vehicle, 21, 21A to 21H...transmitter / receiver unit, 200...object detection device, 301...acquisition unit, 302...detection unit, G...road surface, O...object.

Claims

1. an acquisition unit that acquires a detection distance indicating a distance from a transceiver unit mounted on a vehicle to an object, the detection distance being detected based on a result of transmission of a transmission wave by the transceiver unit and reception of a reflected wave from the object by the transceiver unit, and a reception intensity indicating an intensity of the reflected wave received by the transceiver unit; a detection unit that detects a detection target among the objects based on the reception intensity exceeding an intensity threshold; Equipped with The object detection device, wherein the detection unit increases the intensity threshold when the detection distance is equal to or less than a distance threshold and the detection target is detected.

2. 2. The object detection device according to claim 1, wherein the detection unit increases the intensity threshold when the detection distance is equal to or less than the distance threshold and, after the number of times the detection target is detected is incremented, the number of times the detection target is detected becomes equal to or greater than a number threshold.

3. The object detection device according to claim 1 , wherein the distance threshold is greater than an installation height indicating a height of the transmitting / receiving unit from a road surface.

Images