Object detection device

Abstract

To provide an object detection device capable of detecting an important object such as a pedestrian even with a weak reflection wave while filtering unnecessary reflection waves.SOLUTION: An object detection device according to an embodiment of the present invention includes a detection unit which is set in a vehicle and detects that a range-finding unit which transmits and receives acoustic waves or radio waves has received a reflection wave reflected by an object, an arithmetic unit which obtains an automatic threshold for filtering out background noise based on the reflection wave, and a determination unit which determines whether or not information on the amplitude is used for object detection based on the arithmetic result of the arithmetic unit when the amplitude of the reflection wave exceeding the automatic threshold is detected. The arithmetic unit multiplies an automatic threshold at an amplitude position by an n value set in accordance with the distance of the object indicated by the amplitude to the vehicle to obtain a secondary threshold. When the reflection intensity indicated by the amplitude exceeds the secondary threshold, the determination unit determines that the information related to the amplitude is used for object detection.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] There is an object detection device that detects an object in front of a vehicle while the vehicle is traveling and issues a warning to the driver. For example, in the technology of Patent Document 1, a moving average value calculated by CFAR (Constant False Alarm Rate) processing is subtracted from the received signal of a distance measuring unit that transmits and receives ultrasonic waves, and the variation for each short section is calculated and used as an adaptive threshold. This makes it possible to adaptively change the threshold according to the amplitude of unnecessary reflected waves from the road surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-001811 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the threshold value is lowered as in Patent Document 1, even objects that are not desired to be detected, such as low steps that do not impede the travel of the vehicle, will be detected.

[0005] The present invention has been made in consideration of the above, and provides an object detection device that can detect important objects such as pedestrians even with weak reflected waves while filtering out unnecessary reflected waves. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the objective, an object detection device of an embodiment includes a detection unit that is installed in a vehicle and detects that a distance measuring unit that transmits and receives sound waves or radio waves has received a reflected wave reflected by an object; a calculation unit that calculates an automatic threshold for filtering out background noise based on the reflected wave; and a judgment unit that, when an amplitude of the reflected wave that exceeds the automatic threshold is detected, judges whether or not information regarding the amplitude should be used for object detection based on the calculation result of the calculation unit, wherein the calculation unit multiplies an n value that is set according to the distance of the object from the vehicle indicated by the amplitude by the automatic threshold at the amplitude position to calculate a secondary threshold, and when the reflection intensity indicated by the amplitude exceeds the secondary threshold, the judgment unit judges to use the information regarding the amplitude for object detection. Effect of the Invention

[0007] The object detection device according to the embodiment can detect important objects such as pedestrians even with weak reflected waves while filtering out unnecessary reflected waves. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a top view of a vehicle equipped with an object detection device according to an embodiment. [Diagram 2] FIG. 2 is a block diagram illustrating an example of an overall configuration of an object detection system 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 schematic diagram illustrating an example of an object detection operation performed by the object detection device according to the embodiment. [Diagram 5] FIG. 5 is a schematic diagram illustrating an example of an object detection operation performed by the object detection device according to the embodiment. [Figure 6] FIG. 6 is a schematic diagram illustrating a method for calculating an n value set in the object detection device according to the embodiment. [Figure 7]FIG. 7 is a schematic diagram illustrating a method for calculating an n value set in the object detection device according to the embodiment. [Figure 8] FIG. 8 is a schematic diagram illustrating a method for calculating an n value set in the object detection device according to the embodiment. [Figure 9] FIG. 9 is a schematic diagram illustrating a method for calculating an n value set in the object detection device according to the embodiment. [Figure 10] FIG. 10 is a flowchart illustrating an example of a procedure of the object detection process performed by the object detection device according to the embodiment. [Figure 11] FIG. 11 is a schematic diagram illustrating an example of an object detection operation by an object detection device according to another modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Similar components in the following exemplary embodiments are given the same reference numerals, and duplicated descriptions will be omitted as appropriate.

[0010] (Vehicle configuration example) Fig. 1 is a top view of a vehicle 10 equipped with an object detection device 20 according to an embodiment. The front, rear, left and right of the vehicle 10 in Fig. 1 indicate the directions when viewed from the driver's seat of the vehicle 10.

[0011] The vehicle 10 of the embodiment may be, for example, an internal combustion engine vehicle using an internal combustion engine as a power source, an electric vehicle or a fuel cell vehicle using an electric motor as a power source, or a hybrid vehicle using both of these as a power source.

[0012] The vehicle 10 can be equipped with various transmissions and various systems, parts, and other devices required to drive the internal combustion engine or electric motor. The type, number, layout, and other aspects of the devices related to the drive of the wheels 13 of the vehicle 10 can be set in various ways.

[0013] 1, a vehicle 10 includes a vehicle body 12, a plurality of wheels 13, and a plurality of distance measuring units 14a to 14l. When there is no need to distinguish between the distance measuring units 14a to 14l, they will be simply referred to as distance measuring unit 14.

[0014] The vehicle body 12 constitutes a vehicle cabin in which passengers ride. A plurality of wheels 13 and a plurality of distance measuring units 14 are attached to the vehicle body 12. In the example of Fig. 1, the vehicle body 12 has four wheels 13 and twelve distance measuring units 14. However, the number of distance measuring units 14 attached to the vehicle body 12 is arbitrary.

[0015] The four wheels 13 are provided on the front, rear, left and right sides of the vehicle body 12. The two front wheels 13 function, for example, as steering wheels, and the two rear wheels 13 function, for example, as driving wheels.

[0016] The distance measuring unit 14 is, for example, a sonar provided on the outer periphery of the vehicle 10, which transmits sound waves such as ultrasonic waves and receives the waves reflected by objects such as obstacles present around the vehicle 10. The distance measuring unit 14 may be a radar that transmits electromagnetic waves such as laser light, a millimeter wave radar, or the like.

[0017] The distance measuring unit 14 outputs information on the received reflected wave to the object detection device 20. The distance measuring unit 14 collects, for example, a response time, which is the time from sending a reflected wave to receiving it, as information for identifying the distance between the target object and the vehicle 10. Based on the information collected by the distance measuring unit 14, the object detection device 20 can detect the presence or absence of an obstacle or the like around the vehicle 10 and the distance to the obstacle.

[0018] In addition, when the distance measuring unit 14 receives multiple reflected waves reflected from multiple points on the object in response to a single ultrasonic wave transmission, the distance measuring unit 14 may include only the response time of the reflected wave received earliest in the above information.

[0019] The distance measuring units 14a to 14d are provided at the front of the vehicle body 12. Of these distance measuring units 14a to 14d, the distance measuring units 14b and 14c are also called front sonars, and are provided at the front end of the vehicle 10. The distance measuring units 14b and 14c receive reflected waves from objects in front of the vehicle 10. The distance measuring units 14a and 14d are also called corner sonars, and are provided at the corners of the front of the vehicle 10. The distance measuring units 14a and 14d receive reflected waves from objects on the outside in front of the vehicle 10.

[0020] The distance measuring units 14e to 14h are provided at the rear of the vehicle body 12. Of these distance measuring units 14e to 14h, the distance measuring units 14f and 14g are also called rear sonars, and are provided at the rear end of the vehicle 10. The distance measuring units 14f and 14g receive reflected waves from objects behind the vehicle 10. The distance measuring units 14e and 14h are also called corner sonars, and are provided at the corners of the rear of the vehicle 10. The distance measuring units 14e and 14h receive reflected waves from objects on the outside behind the vehicle 10.

[0021] The distance measuring units 14i to 14l are also called side sonars, and are provided on the sides of the vehicle body 12. Of the distance measuring units 14i to 14l, the distance measuring units 14i and 14j are provided on the front sides of the vehicle 10. The distance measuring units 14k and 14l are provided on the rear sides of the vehicle 10. The distance measuring units 14i to 14l receive reflected waves from objects on the sides of the vehicle 10.

[0022] The vehicle 10 may be provided with a plurality of imaging units capable of capturing images of the periphery of the vehicle 10, in addition to the plurality of distance measuring units 14a to 14l described above.

[0023] (Example of object detection system configuration) 2 is a block diagram showing an example of an overall configuration of an object detection system 200 according to an embodiment. The object detection system 200 is mounted on, for example, a vehicle 10, detects an object based on information output from a distance measuring unit 14, and controls the vehicle 10 based on the object detection result.

[0024] As shown in FIG. 2, the object detection system 200 includes an object detection device 20, a plurality of distance measuring units 14, a braking system 121, a buzzer 122, and an engine 123.

[0025] The object detection device 20 and the multiple distance measurement units 14 are connected by a Distributed System Interface 3 (DSI3), which is an in-vehicle network. The object detection device 20 is also connected to the brake system 121, the buzzer 122, the engine 123, and the shift sensor 124 by a Controller Area Network (CAN), which is an in-vehicle network.

[0026] Each distance measuring unit 14 includes a transducer 141 configured using a piezoelectric element or the like, and an amplifier (not shown), and is configured to be able to transmit and receive ultrasonic waves by the vibration of the transducer 141. Specifically, the distance measuring unit 14 transmits ultrasonic waves generated in response to the vibration of the transducer 141, and detects the vibration of the transducer 141 caused by the reflected waves of the transmitted ultrasonic waves reflected by objects such as the object OB and the road surface RS. The vibration of the transducer 141 is converted into an electric signal, and based on the electric signal, it is possible to obtain the time of flight (TOF) of the ultrasonic waves corresponding to the distance from the distance measuring unit 14 to the object OB, Doppler shift information corresponding to the relative speed between the vehicle 10 and the object OB, and the like.

[0027] 2, a configuration in which both wave transmission and wave reception are performed using a single transducer 141 is illustrated, but the configuration of the distance measuring unit 14 is not limited to this. For example, a configuration in which the wave transmission side and the wave reception side are separated, such as a configuration in which a transducer for wave transmission and a transducer for wave reception are separately provided, may also be used.

[0028] The object detection device 20 is an ECU (Electronic Control Unit) or the like that detects obstacles and the like around the vehicle 10 based on information from the distance measurement unit 14 and controls the vehicle 10. The object detection device 20 can receive various information from the distance measurement unit 14 via the DSI 3. In addition, the object detection device 20 can control the brake system 121 and the engine 123, etc., by sending control signals via the CAN, and can also output sound to the buzzer 122.

[0029] The object detection device 20 includes a central processing unit (CPU) 21, a read only memory (ROM) 22, a random access memory (RAM) 23, and a solid state drive (SSD) 24.

[0030] The CPU 21 can execute various kinds of arithmetic processing and control, such as detecting an object, determining whether or not there is interference with an object, and outputting an alarm to the buzzer 122. The ROM 22 is a non-volatile storage device. A program is stored in the ROM 22 in advance. The CPU 21 can read out the program stored in the ROM 22 and execute arithmetic processing in accordance with the program.

[0031] The RAM 23 temporarily stores various data used in the calculations of the CPU 21. The SSD 24 is a rewritable non-volatile storage unit, and can store data even when the power of the object detection device 20 is turned off.

[0032] The CPU 21, the ROM 22, the RAM 23, and the like may be integrated in the same package. The object detection device 20 may be configured to use another logical operation processor such as a DSP (Digital Signal Processor) or a logical circuit, instead of the CPU 21. The SSD 24 may be replaced by an HDD (Hard Disk Drive), or the SSD 24 or the HDD may be provided separately from the object detection device 20.

[0033] The brake system 121 may be, for example, an anti-lock brake system (ABS) that prevents the brakes from locking, an electronic stability control (ESC) that prevents the vehicle 10 from skidding when cornering, an electric brake system that increases the braking force to perform brake assist, or a brake by wire (BBW).

[0034] The engine 123 is a prime mover that drives the vehicle 10 .

[0035] The buzzer 122 is provided inside the vehicle 10 and outputs an alarm.

[0036] Fig. 3 is a block diagram showing an example of a functional configuration of the object detection device 20 according to the embodiment. As shown in Fig. 3, the object detection device 20 includes a detection unit 201, a calculation unit 202, a determination unit 203, a command unit 204, and a storage unit 205 as functional units.

[0037] These functional units are realized, for example, by the above-mentioned CPU 21 reading out a program stored in a storage device such as the ROM 22, and expanding and executing the program on the RAM 23. Note that some or all of these functional units may be configured by hardware such as a circuit including an ASIC (Application Specific Integrated Circuit).

[0038] The detection unit 201 acquires information regarding the transmission and reception of ultrasonic waves by the distance measurement unit 14. Furthermore, when the amplitude of a reflected wave exceeding an automatic threshold is received from the reception signal by the distance measurement unit 14, the detection unit 201 detects this. The automatic threshold is a threshold calculated based on the reflected wave received by the distance measurement unit 14, and is set to filter out background noise received by the distance measurement unit 14. As a specific calculation method of the automatic threshold, at least one of general algorithms used in, for example, CFAR processing can be used.

[0039] The calculation unit 202 calculates the above-mentioned automatic threshold value using a predetermined algorithm based on the reflected wave acquired by the detection unit 201. When an amplitude exceeding the automatic threshold value is detected, the calculation unit 202 multiplies the automatic threshold value at the amplitude position by the n value to calculate a secondary threshold value. As will be described in detail later, the object detection device 20 has a preset n value that differs according to the distance to the vehicle 10.

[0040] Furthermore, the calculation unit 202 determines the position of the object relative to the vehicle 10 based on the amplitude that indicates the object that is the subject of object detection among the detected amplitudes.

[0041] When an amplitude exceeding the automatic threshold is detected, the determination unit 203 determines whether or not information related to the amplitude is to be used for object detection in the object detection device 20. More specifically, when the amplitude exceeding the automatic threshold exceeds the secondary threshold calculated by the calculation unit 202, the determination unit 203 determines that information related to the amplitude is to be used for object detection, and when the amplitude is less than the secondary threshold, the determination unit 203 determines that information related to the amplitude is not to be used for object detection.

[0042] When it is determined that the amplitude is to be used for object detection, the calculation unit 202 calculates the position of the object related to the amplitude relative to the vehicle 10 based on the information about the amplitude. When it is determined that the amplitude is not to be used for object detection, the amplitude is filtered out.

[0043] When the position of the object calculated by the calculation unit 202 based on the amplitude exceeding the secondary threshold is in a positional relationship that may cause interference with the vehicle 10 after a predetermined time has elapsed, the command unit 204 controls each part of the vehicle 10 to avoid interference between the vehicle 10 and the object.

[0044] More specifically, the command unit 204 sends a command to the buzzer 122 to output an alarm for the driver. The command unit 204 also sends a command to the brake system 121 to apply the brakes. This allows the vehicle 10 to be decelerated or stopped.

[0045] Furthermore, instead of or in addition to braking by the brake system 121, the command unit 204 may send a command to the engine 123 to reduce the output of the engine 123. This also makes it possible to decelerate or stop the vehicle 10.

[0046] The storage unit 205 stores a control program and various control parameters necessary for the operation of the object detection device 20. The storage unit 205 also stores the n value used by the calculation unit 202 to calculate the secondary threshold value.

[0047] (Example of the operation of the object detection device) Next, an operation example of the object detection device 20 according to the embodiment and an example of setting the n value will be described with reference to Fig. 4 to Fig. 9. Fig. 4 and Fig. 5 are schematic diagrams illustrating an example of the object detection operation by the object detection device 20 according to the embodiment.

[0048] Fig. 4 shows an example of a received signal of the distance measuring unit 14 detected by the detection unit 201 at a given time. The horizontal axis of Fig. 4 represents the distance from the vehicle 10, and the vertical axis represents the reflection intensity of the received signal.

[0049] 4, the calculation unit 202 of the object detection device 20 calculates an automatic threshold value based on the received wave signal obtained from the distance measurement unit 14, for example, by CFAR processing. Reflected waves with an intensity less than the automatic threshold value are filtered out as background noise such as unevenness of the road surface.

[0050] 4, an amplitude having a peak value RFp of the reflection intensity and exceeding the automatic threshold is detected at a point at a distance D from the vehicle 10. In this case, the calculation unit 202 multiplies the automatic threshold at that amplitude position by a predetermined n value to obtain a secondary threshold.

[0051] As described above, the value of n is set to a different value depending on the distance from the vehicle 10. In the example of FIG. 4, the distance from the vehicle 10 is distance D α ,D β ,D γ ,D δ At the point, n value is nα ,n β ,n γ ,n δ These settings are stored in, for example, the storage unit 205 as described above.

[0052] As described above, the calculation of the secondary threshold value by the calculation unit 202 is performed at the amplitude position exceeding the automatic threshold value. However, Fig. 4 shows secondary threshold values ​​in which the respective n values ​​are multiplied by the automatic threshold value even at points other than the distance D, which is the amplitude position exceeding the automatic threshold value.

[0053] FIG. 5 is an enlarged view of the amplitude having the peak value RFp, and shows the details of the method of calculating the secondary threshold value at the amplitude position.

[0054] 5, the calculation unit 202 extracts an automatic threshold value THex at a first point where the amplitude having the peak value RFp exceeds the automatic threshold value, and an automatic threshold value THsh at a second point where the amplitude is less than the automatic threshold value. In addition, the calculation unit 202 calculates an average value (THex+THsh) / 2 of the automatic threshold values ​​THex and THsh as the automatic threshold value at a distance D from the vehicle 10 where the peak value RFp is detected.

[0055] It may be difficult to accurately determine the actual automatic threshold at the distance D where the peak value RFp is detected, and as an alternative, the average value of the automatic thresholds THex and THsh can be used as the automatic threshold THav at the distance D, which can obtain a value that is sufficiently close to the actual automatic threshold at the distance D.

[0056] In addition, the n value set at the distance D is n p If so, the calculation unit 202 calculates n p is multiplied by the automatic threshold value THav obtained as above. This results in the secondary threshold value (THav×n p ) is obtained.

[0057] If the detected amplitude peak value RFp exceeds the secondary threshold at the distance D, the determination unit 203 determines that information related to this amplitude is to be used for object detection. If the detected amplitude peak value RFp is less than the secondary threshold at the distance D, the determination unit 203 determines that information related to this amplitude is not to be used for object detection.

[0058] 6 to 9 are schematic diagrams illustrating a method for calculating the n value set in the object detection device 20 according to the embodiment.

[0059] 6 and 7 show a calculation method of the n value used when setting a secondary threshold for reflected waves obtained from a low step. A low step is located on the road surface and is low enough that the vehicle 10 can overcome it, and is an example of an object that is desired to be filtered out during object detection. In the example of Fig. 6 and Fig. 7, reflected waves obtained from unevenness of the road surface such as asphalt are treated as background noise, and an automatic threshold is set to filter out such reflected waves.

[0060] As shown in Fig. 6, when a secondary threshold is set for a low step, the distance to the vehicle 10 is varied and the intensity of the reflected wave obtained from the low step is measured. 11 ~ST 14 The reflection intensity of the reflected wave increases rapidly until the vehicle 10 reaches a low level step ST 15 ~ST 17 In this case, the reflection intensity of the reflected wave is substantially constant.

[0061] In the above measurement of the reflected wave obtained from the low step, the conditions such as temperature and humidity that affect the reflection intensity are set to be the same as the conditions when measuring the reflected wave obtained from the unevenness of the road surface. However, since the low step is located close to the road surface below the vehicle 10, it is expected that errors due to temperature and humidity are unlikely to occur in the reflected waves obtained from the low step and the unevenness of the road surface. Similarly, it is considered that the influence of the vertical directivity of the distance measuring unit 14 provided on the vehicle 10 and the mounting angle on the vehicle 10 are also small between these reflected waves.

[0062] As shown in FIG. 7, the reflection intensity at each distance of the small step obtained above is divided by the reflection intensity due to the unevenness of the road surface at the same distance to obtain the n value (n 11 ~n 17 When actually detecting an object while the vehicle 10 is traveling, the secondary threshold is obtained by multiplying the automatic threshold at that point by the value of n corresponding to the amplitude position of the reflected wave that exceeds the automatic threshold.

[0063] Figures 8 and 9 show a method for calculating the n value used when setting a secondary threshold for the reflected wave obtained from a pole. A pole is an example of an object to be detected during object detection. In the examples of Figures 8 and 9, the reflected wave obtained from unevenness of the road surface such as asphalt is treated as background noise, and an automatic threshold is set to filter out such reflected waves.

[0064] As shown in Fig. 8, when a secondary threshold is set for a pole, the distance from the vehicle 10 is varied and the intensity of the reflected wave obtained from the pole is measured. In the example of Fig. 8, as the distance from the vehicle 10 increases, the pole PL 21 ~PL 27 The reflected wave strength from the

[0065] In addition, in the above measurement of the reflected wave obtained from the pole, the conditions such as temperature and humidity that affect the reflection intensity are set to be the same as the conditions when measuring the reflected wave obtained from the unevenness of the road surface. It is expected that errors due to temperature and humidity are likely to occur in the reflected wave obtained from the unevenness of the road surface and the object directly facing the vehicle 10, such as a pedestrian or bicycle, other than the pole illustrated in FIG. 8. In addition, the reflected wave from the object and the unevenness of the road surface also has a different incidence angle when entering the distance measuring unit 14, so it is considered that the influence of the vertical directivity of the distance measuring unit 14 provided on the vehicle 10 and the mounting angle on the vehicle 10 are also large. Therefore, it is necessary to set the secondary threshold value taking into account the vertical directivity and mounting accuracy of the distance measuring unit 14.

[0066] As shown in FIG. 9, the reflection intensity at each distance from the pole obtained above is divided by the reflection intensity due to the unevenness of the road surface at the same distance to obtain the n value (n 21 ~n 27 When actually detecting an object while the vehicle 10 is traveling, the secondary threshold is obtained by multiplying the automatic threshold at that point by the value of n corresponding to the amplitude position of the reflected wave that exceeds the automatic threshold.

[0067] As described above, by setting the ratio of the reflected waves from an object that you want to filter out during object detection, or the reflected waves from an object that you want to target for object detection, to the reflected waves obtained from background noise as the n value, you can obtain a secondary threshold that can filter out unnecessary reflected waves while suppressing the effects of temperature and humidity, and detect important objects such as pedestrians.

[0068] The storage unit 205 of the object detection device 20 may store multiple types of n values ​​obtained from reflected waves from multiple types of objects to be filtered out during object detection, and multiple types of n values ​​obtained from reflected waves from multiple types of objects to be targeted for object detection. When calculating the secondary threshold, the calculation unit 202 may use different n values ​​depending on the situation of the traveling vehicle 10 at each time. Alternatively, the calculation unit 202 may use n values ​​obtained from different objects at different times to calculate the secondary threshold.

[0069] 6 to 9, the reflected waves from unevenness of the road surface, which is background noise, the reflected waves from small steps, and the reflected waves from poles are obtained by measurement. However, at least any of these may be obtained by simulation or the like.

[0070] (Example of processing by an object detection device) Next, an example of an object detection process by the object detection device 20 according to the embodiment will be described with reference to Fig. 10. Fig. 10 is a flow diagram showing an example of a procedure of the object detection process by the object detection device 20 according to the embodiment.

[0071] 10, for example, when the vehicle 10 starts traveling at a predetermined speed, the object detection device 20 starts the object detection process (step S101). In response, the detection unit 201 acquires the received wave signal from the distance measurement unit 14 and monitors whether there is an amplitude of the reflected wave that exceeds the automatic threshold (step S102). If no amplitude exceeding the automatic threshold is detected (step S102: No), the process at that time ends and proceeds to the process of step S111.

[0072] If the detection unit 201 detects an amplitude exceeding the automatic threshold (step S102: Yes), the calculation unit 202 extracts reflected wave information such as the automatic threshold at the point where the amplitude exceeded the automatic threshold, the peak value of the amplitude, and the automatic threshold at the point where the amplitude became less than the automatic threshold from the detection result by the detection unit 201 (step S103).The calculation unit 202 also calculates a secondary threshold based on the extracted reflected wave information (step S104).

[0073] That is, the calculation unit 202 calculates the average value of the automatic thresholds at the points where the amplitude exceeds the automatic threshold and the points where it falls below the automatic threshold, multiplies this average value by the n value set at the position of the peak amplitude value, and sets the result as the secondary threshold value.

[0074] The determination unit 203 determines whether or not the peak value of the amplitude is less than the secondary threshold value calculated by the calculation unit 202 (step S105). If the peak value of the amplitude is less than the secondary threshold value (step S105: Yes), the determination unit 203 determines not to use information on this amplitude for object detection, and filters out this information (step S107).

[0075] If the peak value of the amplitude exceeds the secondary threshold (step S105: No), the determination unit 203 determines whether the information on the amplitude is to be used for object detection (step S106). In this case, the calculation unit 202 determines the position of the object identified based on the information on the amplitude with respect to the vehicle 10 (step S108).

[0076] The determination unit 203 determines whether or not control of the vehicle 10 is necessary based on the positional relationship of the object with respect to the vehicle 10 obtained by the calculation unit 202 (step S109).

[0077] When the object indicated by the amplitude is in a position that may interfere with the vehicle 10 after a predetermined time, for example, the determination unit 203 determines that it is necessary to control the vehicle 10 to avoid interference with the object (step S109: Yes). The command unit 204 controls each part of the vehicle 10 based on such a determination result (step S110).

[0078] At this time, the command unit 204 outputs a warning from the buzzer 122 inside the vehicle cabin to alert the driver, applies the brakes to the vehicle 10 using the brake system 121, and / or decelerates the vehicle 10 by reducing the output of the engine 123, for example.

[0079] If the object indicated by the above amplitude is in a position where it will not interfere with the vehicle 10 after a predetermined time, for example, the judgment unit 203 judges that control of the vehicle 10 is unnecessary (step S109: No), and the processing of step S110 is skipped.

[0080] Thereafter, if the vehicle 10 is still traveling at or above the predetermined speed, the object detection device 20 continues the object detection process (step S111: No) and repeats the process from step S102. If the vehicle 10 stops, for example, the object detection device 20 ends the object detection process (step S111: Yes).

[0081] This completes the object detection process by the object detection device 20 of the embodiment.

[0082] (Overview) In an object detection device that detects objects around a vehicle, an automatic threshold obtained by, for example, CFAR processing is used to filter out reflected waves from road irregularities and other things that would not hinder the vehicle's movement as background noise.

[0083] However, when filtering is performed uniformly using an automatic threshold, there is a risk that weak reflected waves from, for example, pedestrians may be filtered out. In this way, for example, reflected waves from pedestrians and reflected waves from the above-mentioned background noise may be detected with relatively similar intensities, making it difficult to distinguish between them.

[0084] Furthermore, the automatic threshold includes errors due to temperature and humidity, and there is a concern that if the automatic threshold is applied as is, the detection results that include these errors may be obtained when detecting an object.

[0085] According to the object detection device 20 of the embodiment, the calculation unit 202 multiplies the automatic threshold at the amplitude position by the n value, which is set according to the distance from the vehicle 10 to the object indicated by the amplitude exceeding the automatic threshold, to obtain the secondary threshold. In this way, by once selecting the reflected waves obtained from the distance measurement unit 14 using the automatic threshold, even a weak reflected wave can be detected. After that, by further selecting using the secondary threshold, it is possible to detect important objects such as pedestrians even if the reflected waves are weak, while filtering out unnecessary reflected waves.

[0086] According to the object detection device 20 of the embodiment, the calculation unit 202 determines the secondary threshold by multiplying the average value of the automatic threshold THex at the point where the amplitude exceeds the automatic threshold and the automatic threshold THsh at the point where the amplitude falls below the automatic threshold as the automatic threshold THav at the amplitude position by the n value. This makes it possible to determine an approximation of the automatic threshold at the peak value RFp position and appropriately set the secondary threshold.

[0087] According to the embodiment of the object detection device 20, the reflected waves obtained from the object to be detected are obtained in advance according to the distance to the vehicle 10, the reflected waves indicated by the background noise are obtained in advance according to the distance to the vehicle 10, and the value obtained by dividing the reflected waves obtained from the object by the reflected waves indicated by the background noise is set as the n value according to the distance to the vehicle 10.

[0088] This makes it possible to cancel temperature and humidity errors contained in the automatic threshold value, and also makes it possible to appropriately set the secondary threshold value by taking into account the vertical directivity of the ranging unit 14 installed in the vehicle 10 and the effects of the mounting angle on the vehicle 10, etc.

[0089] In the embodiment, the average value of the automatic thresholds at the points where the amplitude exceeds the automatic threshold and the points where the amplitude falls below the automatic threshold is calculated, and the average value is used as the automatic threshold at the point where the peak value of the amplitude is detected. However, if it is possible to specify the automatic threshold at the point where the peak value is detected with high accuracy, the actual automatic threshold may be used as it is to generate the secondary threshold. This is shown in FIG.

[0090] Fig. 11 is a schematic diagram illustrating an example of an object detection operation by an object detection device according to another modified example of the embodiment. In the example shown in Fig. 11, it is assumed that an amplitude having a peak value RFp of reflection intensity and exceeding the automatic threshold is detected at a point at a distance D from the vehicle 10.

[0091] As shown in FIG. 11, the calculation section 202 extracts an automatic threshold value THp at the position of the peak value RFp in the amplitude having the peak value RFp.

[0092] In addition, the n value set at the distance D is n p If so, the calculation unit 202 calculates n p This multiplies the automatic threshold value THp at the peak value RFp position. This gives the secondary threshold value (THp×n p ) is obtained.

[0093] If the detected amplitude peak value RFp exceeds the secondary threshold at the distance D, the determination unit 203 determines whether or not to use information relating to this amplitude for object detection.

[0094] In this way, by setting the automatic threshold value THp at the peak position in the amplitude exceeding the automatic threshold value as the automatic threshold value at the amplitude position and multiplying it by the n value to obtain the secondary threshold value, it is possible to set the secondary threshold value more precisely. [Explanation of symbols]

[0095] 10. Vehicle 14...Distance measurement section 20...Object detection device 201…Detection unit 202...Arithmetic section 203...Judgment section 204...Command Department 205...Storage section

Claims

1. a detection unit that is provided in the vehicle and detects that a distance measuring unit that transmits and receives sound waves or radio waves has received a reflected wave reflected by an object; A calculation unit that calculates an automatic threshold for filtering out background noise based on the reflected wave; a determination unit that, when an amplitude of a reflected wave exceeding the automatic threshold is detected, determines whether or not information about the amplitude is to be used for object detection based on a calculation result of the calculation unit, The calculation unit is multiplying the automatic threshold value at the amplitude position by a value n that is set according to the distance of the object relative to the vehicle, the value being indicated by the amplitude, to obtain a secondary threshold value; The determination unit is When the reflection intensity indicated by the amplitude exceeds the secondary threshold, it is determined that information regarding the amplitude is used for object detection. Object detection device.

2. The calculation unit is the automatic threshold value at the amplitude position is determined as an average value of the automatic threshold value at a first point where the amplitude exceeds the automatic threshold value and the automatic threshold value at a second point where the amplitude becomes less than the automatic threshold value, and the average value is multiplied by the n value to obtain the secondary threshold value. The object detection device according to claim 1 .

3. The calculation unit is The automatic threshold value at the peak position in the amplitude is set as the automatic threshold value at the amplitude position, and multiplied by the n value to obtain the secondary threshold value. The object detection device according to claim 1 .

4. acquiring in advance a first reflected wave obtained from an object to be detected according to a distance to the vehicle; A second reflected wave indicated by the background noise is acquired in advance according to a distance to the vehicle; A value obtained by dividing the first reflected wave by the second reflected wave is set as the n value according to the distance to the vehicle. The object detection device according to claim 1 .

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