Object detection device

Abstract

To provide an object detection device capable of detecting an important object of a pedestrian or the like even if reflection waves are weak while filtering unwanted reflection waves.SOLUTION: An object detection device includes: an operation section for obtaining a position of an object relative to a vehicle on the basis of reflection waves reflected by the object; and a determination section for determining whether reflection waves are utilized for detecting an object on the basis of an operation result of the operation section. The operation section obtains a distance of a first object relative to a vehicle on the basis of first reflection waves as a first distance, and obtains a distance of a second object relative to a vehicle on the basis of second reflection waves as a second distance when reflection waves exceed an automatic threshold, and includes the first reflection waves reflected by the first object and the second reflection waves reflected by the second object, and obtains a difference between the first distance and the second distance, and the determination section utilizes the first and second reflection waves for detecting an object when the difference between the first distance and the second distance is equal to or less than a first threshold.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 object, an object detection device of an embodiment includes a detection unit provided in a vehicle and detects that a ranging unit that transmits and receives sound waves or radio waves has received a reflected wave reflected by an object; a calculation unit that determines the position of the object relative to the vehicle based on the reflected wave; and a judgment unit that determines whether or not to use the reflected wave for object detection based on the calculation result of the calculation unit, wherein if the reflected wave exceeds an automatic threshold set based on background noise and includes a first reflected wave reflected by a first object and a second reflected wave reflected by a second object, the calculation unit calculates the distance of the first object relative to the vehicle based on the first reflected wave as a first distance, calculates the distance of the second object relative to the vehicle based on the second reflected wave as a second distance, and calculates the difference between the first and second distances, and the judgment unit determines whether or not to use the first and second reflected waves for object detection based on at least whether the difference between the first and second distances is equal to or less than a first threshold. 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 an example of an object detection operation performed by the object detection device according to the embodiment. [Figure 7] FIG. 7 is a schematic diagram illustrating an example of an object detection operation performed by the object detection device according to the embodiment. [Figure 8] FIG. 8 is a schematic diagram illustrating an example of an object detection operation performed by the object detection device according to the embodiment. [Figure 9] FIG. 9 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 10] FIG. 10 is a flowchart illustrating an example of a procedure of an object detection process performed by an object detection device according to another modified example of the embodiment. [Figure 11] FIG. 11 is a flowchart illustrating an example of a procedure of an object detection process performed 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 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 distance measurement units 14 are connected by a LIN (Local Interconnect Network), which is an in-vehicle network. The object detection device 20 is also connected by a CAN (Controller Area Network), which is an in-vehicle network, to the brake system 121, the buzzer 122, the engine 123, and the shift sensor 124.

[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 LIN. In addition, the object detection device 20 can control the brake system 121 and the engine 123, etc., by sending control signals via 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 a reflected wave exceeding an automatic threshold is received from the reception signal by the distance measurement unit 14, the detection unit 201 detects it. The automatic threshold is background noise calculated from the reflected wave received by the distance measurement unit 14. As a specific method for calculating the automatic threshold, at least one of general algorithms used in, for example, CFAR processing can be used.

[0039] The calculation unit 202 determines the position of the object relative to the vehicle 10 based on the reflected waves detected by the detection unit 201. When multiple reflected waves exceeding the automatic threshold are detected at the same time, the calculation unit 202 calculates the distance between the objects from the reflected waves. Furthermore, the calculation unit 202 determines the coordinates of each object relative to the vehicle 10 from the reflected waves and calculates the position difference between these objects.

[0040] The determination unit 203 determines whether or not the reflected wave detected by the detection unit 201 is to be used for object detection in the object detection device 20.

[0041] Among obstacles that may impede the travel of the vehicle 10, poles and steps of a certain height or higher have a relatively simple appearance, and are likely to return a relatively strong single reflected wave due to a single reflection. On the other hand, pedestrians and bicycles have complex shapes, and often return multiple relatively weak reflected waves due to multiple reflections.

[0042] Therefore, the judgment unit 203 judges whether multiple reflected waves with an intensity exceeding the automatic threshold have been detected at the same time, and if multiple reflected waves have been detected, judges from those reflected waves whether the distance and position difference between multiple objects identified by the above-mentioned calculation unit 202 are within a predetermined threshold.

[0043] If the distance and position difference between objects are within a certain threshold, it indicates that these objects are sufficiently close to each other, and they are not considered to be multiple independent objects, but rather correspond to different parts of a single object such as a pedestrian or bicycle. In other words, the multiple detected reflected waves are considered to be multiple reflections from multiple parts of a single object.

[0044] On the other hand, when a single reflected wave exceeding the automatic threshold is detected, it is highly likely to be a single reflection from an object with a simple appearance such as a pole. Even if at least one of the distance and position difference between objects identified from multiple reflected waves exceeds the corresponding threshold, it is possible that the reflected wave is a single reflection from each of multiple objects with a simple appearance.

[0045] Therefore, when the intensity of such a reflected wave is equal to or greater than a threshold value applied to a single reflected wave, the determining unit 203 determines that the reflected wave is to be used for object detection.

[0046] However, if the intensity of the reflected waves is less than the threshold value applied to single reflected waves, they are considered to be noise from an object such as an uneven road surface that cannot hinder the travel of the vehicle 10. Therefore, the determination unit 203 determines not to use these reflected waves for object detection. In this case, these reflected waves are filtered out.

[0047] When the position of the object calculated by the calculation unit 202 based on the reflected waves due to multiple reflections or single reflections 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.

[0048] 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.

[0049] 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.

[0050] 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 a plurality of thresholds used by the determination unit 203 for various determinations.

[0051] (Example of the operation of the object detection device) Next, an example of the operation of the object detection device 20 according to the embodiment will be described with reference to Fig. 4 to Fig. 9. Fig. 4 to Fig. 9 are schematic diagrams illustrating an example of the object detection operation by the object detection device 20 according to the embodiment.

[0052] Fig. 4 shows how, when the vehicle 10 is moving forward, multiple distance measuring units 14 in front of the vehicle 10 transmit ultrasonic waves to a pedestrian M crossing in front of the vehicle 10 and receive the reflected waves. As shown in Fig. 4, since the pedestrian M has a complex shape, the transmitted ultrasonic waves are reflected multiple times and received by the distance measuring units 14. In the example of Fig. 4, reflected waves RFa, RFb, RFc, RFd, and RFe are generated by ultrasonic waves hitting the left hand, right hand, left foot, right foot, and torso of the pedestrian M, respectively.

[0053] Fig. 5 shows an example of a received signal of the distance measuring unit 14 detected by the detection unit 201 in the above case. The horizontal axis of Fig. 5 represents the distance from the vehicle 10, and the vertical axis represents the reflection intensity of the received signal. In the object detection device 20 of the embodiment, as described above, an automatic threshold is set based on the received signal obtained from the distance measuring unit 14, for example, by CFAR processing. Reflected waves with an intensity below the automatic threshold are filtered out as background noise, such as unevenness of the road surface.

[0054] 5, it is assumed that, among the reflected waves RFa to RFe from various parts of the pedestrian M, the reflected wave RFa reflected from the left hand and the reflected wave RFb reflected from the right hand have intensities exceeding the automatic threshold. In this case, the determination unit 203 determines that a plurality of reflected waves RFa and RFb exceeding the automatic threshold have been detected.

[0055] 6, when multiple reflected waves RFa, RFb exceeding the automatic threshold are detected, the calculation unit 202 calculates the distance from the vehicle 10 to the object identified based on the reflected wave RFa. The calculation unit 202 also calculates the distance from the vehicle 10 to the object identified based on the reflected wave RFb. In this manner, the distance from each object to the vehicle 10 can be calculated, for example, from a received wave signal of one distance measuring unit 14. From the above, the distances from the vehicle 10 to the left and right of the pedestrian M at a given time are calculated.

[0056] Note that the reflected waves RFa and RFb are examples of the first and second reflected waves, respectively, the left and right hands of pedestrian M are examples of the first and second objects, and the distances of pedestrian M's left and right hands from vehicle 10 are examples of the first and second distances, respectively.

[0057] The calculation unit 202 further obtains a difference D between these distances from the distances of the objects corresponding to the reflected waves RFa and RFb to the vehicle 10. This determines the distance between the left hand and the right hand of the pedestrian M. The judgment unit 203 judges whether or not the difference D between these distances calculated by the calculation unit 202 is equal to or smaller than a predetermined threshold value.

[0058] The threshold value at this time is set in advance based on the average size of an object that is likely to cause multiple reflections, such as a pedestrian M or a bicycle. More specifically, the threshold value is set based on the two-dimensional size of an object, such as a pedestrian M, that coincides with the traveling direction of the vehicle 10. The threshold value applied to the distance difference D calculated by the calculation unit 202 is an example of a first threshold value.

[0059] 7, the calculation unit 202 also determines the coordinates of an object identified based on the reflected wave RFa relative to the vehicle 10. The calculation unit 202 also determines the coordinates of an object identified based on the reflected wave RFb relative to the vehicle 10. In this manner, the coordinates of each object relative to the vehicle 10 can be determined using, for example, triangulation using the received signals of multiple distance measuring units 14.

[0060] Through the above calculation, the three-dimensional position coordinates of the vehicle 10 on the left and right hands of the pedestrian M at a given time are obtained. The coordinates of the vehicle 10 on the left and right hands of the pedestrian M are examples of the first and second coordinates, respectively.

[0061] The calculation unit 202 further obtains a position difference P between these coordinates from the coordinates of the objects corresponding to the reflected waves RFa, RFb relative to the vehicle 10. This results in the position difference between the left and right hands of the pedestrian M being obtained. In other words, these position difference P can be expressed, for example, as the two coordinates being separated by a distance x in the X direction and a distance y in the Y direction. The determination unit 203 determines whether these position differences P calculated by the calculation unit 202 are equal to or smaller than a predetermined threshold value.

[0062] The threshold value at this time is also set in advance based on the average size of an object that is likely to cause multiple reflections, such as a pedestrian M or a bicycle. More specifically, the threshold value is set based on the three-dimensional size of an object, such as a pedestrian M, expressed by XY coordinates or the like relative to the vehicle 10. The threshold value applied to the position difference P calculated by the calculation unit 202 is an example of a second threshold value.

[0063] If multiple reflected waves exceeding the automatic threshold are detected and the distances and positional differences between multiple objects based on these reflected waves are within predetermined thresholds, these reflected waves are considered to be multiple reflections from a single object having a complex shape such as a pedestrian M. Therefore, the determination unit 203 determines that these reflected waves are to be used for object detection even if they are weak.

[0064] On the other hand, when a single reflected wave exceeding the automatic threshold is detected, as described above, it may be a single reflection from an object having a simple shape such as a pole. Also, when multiple reflected waves exceeding the automatic threshold are detected, even if at least one of the distance and position difference between the objects identified from these reflected waves exceeds the corresponding threshold, it is possible that the reflected waves due to single reflections from multiple objects were detected at the same time.

[0065] As shown in FIG. 8, the determining unit 203 determines whether or not such a reflected wave is less than a predetermined threshold value that is set in advance for detecting a single reflection.

[0066] The strength of the reflected wave due to a single reflection is usually higher than that due to multiple reflections from a pedestrian M or the like. Therefore, the threshold value at this time is set based on the average strength of the reflected wave due to a single reflection. Also, since the strength of the reflected wave due to a single reflection can change depending on the distance from the vehicle 10, a different value is set as the threshold value applied to the single reflection depending on the distance from the vehicle 10. The above threshold value set to detect the single reflected wave is an example of a third threshold value.

[0067] If the single reflected wave exceeding the automatic threshold is equal to or greater than the threshold applied to the single reflected wave, the determination unit 203 determines to use the reflected wave for object detection. On the other hand, if the single reflected wave exceeding the automatic threshold is less than the threshold applied to the single reflected wave, the determination unit 203 determines not to use the reflected wave for object detection.

[0068] In addition, even if at least one of the distance and the position difference between objects identified from the multiple reflected waves exceeds the corresponding threshold, there is a possibility that the reflected waves due to single reflections from multiple objects are detected at the same time. Therefore, even in such a case, the determination unit 203 determines whether each of these reflected waves is less than the above-mentioned threshold applied to the single reflected wave.

[0069] If any of the multiple reflected waves exceeding the automatic threshold is equal to or greater than the threshold applied to single reflected waves, the determination unit 203 determines whether to use this reflected wave for object detection. At this time, if some or all of the multiple reflected waves have an intensity equal to or greater than the threshold, it means that a number of independent objects equal to the number of detected reflected waves have been detected.

[0070] On the other hand, if any of the reflected waves exceeding the automatic threshold is less than the threshold applied to the single reflected wave, the determination unit 203 determines not to use this reflected wave for object detection. In this case, this reflected wave is filtered out.

[0071] This completes the operation of the object detection device 20 of the embodiment at a given time.

[0072] (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. 9. Fig. 9 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.

[0073] 9, 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 a received wave signal from the distance measurement unit 14 and monitors whether a reflected wave exceeding the automatic threshold is detected (step S102). If a reflected wave exceeding the automatic threshold is not detected (step S102: No), the process at that time ends and the process proceeds to step S112.

[0074] When the detection unit 201 detects a reflected wave exceeding the automatic threshold (step S102: Yes), the determination unit 203 determines whether or not the number of detected reflected waves is two or more (step S103).

[0075] If the determination unit 203 determines that two or more reflected waves have been detected (step S103: Yes), the calculation unit 202 calculates the difference in distance between a plurality of objects identified based on these reflected waves (step S104).

[0076] The determination unit 203 determines whether the difference in distance between the multiple objects obtained by the calculation unit 202 is equal to or less than the corresponding threshold value (step S105). If the determination unit 203 determines that the difference in distance between the multiple objects is equal to or less than the predetermined threshold value (step S105: Yes), the calculation unit 202 obtains the coordinates of the multiple objects identified based on these reflected waves with respect to the vehicle 10, and obtains the positional difference between these objects from these coordinates (step S106).

[0077] The determination unit 203 determines whether the position difference among the multiple objects calculated by the calculation unit 202 is equal to or less than the corresponding threshold (step S107). If the position difference among the multiple objects is equal to or less than the predetermined threshold (step S107: Yes), the determination unit 203 determines whether to use these reflected waves for object detection (step S108).

[0078] On the other hand, if the detection unit 201 detects a single reflected wave (step S103: No), if the detection unit 201 detects multiple reflected waves but the difference in distance between the multiple objects based on these exceeds the corresponding threshold (step S105: No), or if the difference in position between the multiple objects based on these exceeds the corresponding threshold (step S107: No), the judgment unit 203 judges whether or not the detected single or multiple reflected waves are less than the threshold applied to a single reflected wave (step S109).

[0079] If any of the reflected waves is less than the threshold for a single reflected wave (step S109: Yes), the determination unit 203 determines not to use the reflected wave for object detection, and accordingly, the reflected wave is filtered out (step S110).If any of the reflected waves is equal to or greater than the threshold for a single reflected wave (step S109: No), the determination unit 203 determines to use the reflected wave for object detection (step S108).

[0080] When there are reflected waves determined to be used for object detection, the determination unit 203 determines whether or not control of the vehicle 10 is necessary from the positional relationship of the object with respect to the vehicle 10 based on these reflected waves (step S111).

[0081] When the object corresponding to the reflected wave is in a position where it 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 S111: Yes). The command unit 204 controls each part of the vehicle 10 based on such a determination result (step S112).

[0082] 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.

[0083] If the object corresponding to the reflected wave 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 S111: No), and the processing of step S112 is skipped.

[0084] Thereafter, if the vehicle 10 is traveling at or above a predetermined speed, the object detection device 20 continues the object detection process (step S113: 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 S113).

[0085] This completes the object detection process by the object detection device 20 of the embodiment.

[0086] (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.

[0087] However, when filtering is performed uniformly using an automatic threshold, there is a risk that weak reflected waves due to multiple reflections from objects with complex shapes such as 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.

[0088] According to the object detection device 20 of the embodiment, when the reflected waves include two or more reflected waves that exceed an automatic threshold set based on background noise, the calculation unit 202 calculates the distance to the vehicle 10 of the corresponding object based on one of the reflected waves, and calculates the distance to the vehicle 10 of the corresponding object based on the other reflected wave, and calculates the difference between these distances. The determination unit 203 determines whether or not to use these reflected waves for object detection based on whether or not the difference between these distances is equal to or smaller than a corresponding predetermined threshold.

[0089] As a result, it is possible to determine whether these reflected waves are multiple reflections from different parts of a single object, and to determine whether they should be filtered out as background noise, etc. Therefore, it is possible to detect important objects such as pedestrians even if the reflected waves are weak, while filtering out unnecessary reflected waves.

[0090] According to the object detection device 20 of the embodiment, when the reflected waves include two or more reflected waves exceeding an automatic threshold set based on background noise, the calculation unit 202 determines the coordinates of the corresponding object relative to the vehicle 10 based on one of the reflected waves, and determines the coordinates of the corresponding object relative to the vehicle 10 based on the other reflected wave, and determines the position difference between these coordinates. If the difference in the distances is equal to or less than the corresponding threshold and the position difference between the coordinates is equal to or less than the corresponding predetermined threshold, the determination unit 203 determines to use these reflected waves for object detection.

[0091] As described above, by determining the position difference between multiple objects in addition to the difference in distance between these objects, it is possible to more precisely determine whether these reflected waves are multiple reflections from different parts of a single object.

[0092] According to the embodiment of the object detection device 20, when the difference in distance between the plurality of objects exceeds the corresponding threshold value described above, or the difference in position in coordinates between the plurality of objects exceeds the corresponding threshold value described above, the determination unit 203 determines whether or not to use these reflected waves for object detection based on whether or not the reflection intensity of these reflected waves is less than a threshold value that is set to a value greater than the automatic threshold value for detecting a single reflected wave.

[0093] This makes it possible to detect multiple objects even when they actually exist independently. In addition, by clearly distinguishing that the multiple detected reflected waves are not reflected waves due to multiple reflections, and using a threshold value that is applied to single reflected waves, it is possible to determine whether or not these reflected waves should be filtered out as background noise, etc.

[0094] In the above embodiment, when multiple reflected waves are detected at the same time, the calculation unit 202 calculates the distance difference and position difference for the multiple objects based on these reflected waves, and the determination unit 203 determines whether or not these distance differences and position differences are equal to or less than the corresponding thresholds. However, it may be possible to determine whether or not multiple reflected waves detected at the same time are due to multiple reflections based on only one of the distance differences and position differences for the multiple objects. Examples of processing in such a case are shown in Figs. 10 and 11.

[0095] Fig. 10 is a flow diagram showing an example of the procedure of object detection processing by an object detection device according to another modified example of the embodiment. The processing of steps S201 to S205 and the processing of steps S208 to S213 in Fig. 10 correspond to the processing of steps S101 to S105 and the processing of steps S108 to S113 in Fig. 9 of the above-mentioned embodiment, respectively. In this way, in the example of Fig. 10, when multiple reflected waves are detected at the same time, it is determined whether or not these reflected waves are due to multiple reflections without determining the position difference between the multiple objects.

[0096] Calculating the three-dimensional coordinates of multiple objects and judging the positional differences based on the coordinates may increase the load of the internal processing of the object detection device. In the example shown in Fig. 10, such processing is not performed, so the load on the object detection device is reduced and it is easier to judge whether or not to filter out multiple reflected waves.

[0097] Fig. 11 is a flow diagram showing an example of the procedure of object detection processing by an object detection device according to another modified example of the embodiment. The processing of steps S301 to S303 and the processing of steps S306 to S313 in Fig. 11 correspond to the processing of steps S101 to S103 and the processing of steps S106 to S113 in Fig. 9 of the above-mentioned embodiment, respectively. In this way, in the example of Fig. 11, when multiple reflected waves are detected at the same time, it is determined whether or not these reflected waves are due to multiple reflections without determining the difference in distance between the multiple objects.

[0098] By determining the three-dimensional coordinates of multiple objects and judging the position difference based on the three-dimensional coordinates, the proximity between multiple objects can be determined more accurately than when the two-dimensional distance difference between the multiple objects is used. Therefore, sufficient judgment accuracy can be obtained without judging the two-dimensional distance difference between the multiple objects.

[0099] In the above-described embodiment, the judgment is made using both the two-dimensional distance difference and the three-dimensional position difference for multiple objects, thereby improving the judgment accuracy even more than the examples of Figures 10 and 11.

[0100] In this way, when determining whether multiple reflected waves are due to multiple reflections, it is possible to arbitrarily determine which two-dimensional distance differences and three-dimensional position differences for multiple objects to use and in what combination depending on the type, specifications, driving environment, etc. of the vehicle 10. [Explanation of symbols]

[0101] 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 for calculating a position of the object relative to the vehicle based on the reflected wave; a determination unit that determines whether or not to use the reflected wave for object detection based on a calculation result of the calculation unit, The calculation unit is When the reflected waves exceed an automatic threshold value set based on background noise and include a first reflected wave reflected by a first object and a second reflected wave reflected by a second object, determining a distance of the first object relative to the vehicle based on the first reflected wave as a first distance; determining a distance of the second object relative to the vehicle based on the second reflected wave as a second distance; determining a difference between the first and second distances; The determination unit is determining whether or not to use the first and second reflected waves for object detection based on whether or not a difference between at least the first and second distances is equal to or less than a first threshold; Object detection device.

2. The calculation unit is determining a difference between the first and second distances; determining a coordinate of the first object relative to the vehicle based on the first reflected wave as a first coordinate; determining a coordinate of the second object relative to the vehicle based on the second reflected wave as a second coordinate; determining a position difference between the first and second coordinates; The determination unit is When the difference between the first and second distances is equal to or less than the first threshold value and the position difference between the first and second coordinates is equal to or less than a second threshold value, it is determined that the first and second reflected waves are to be used for object detection. The object detection device according to claim 1 .

3. The determination unit is if the difference between the first and second distances exceeds the first threshold value, or if the position difference between the first and second coordinates exceeds the second threshold value, determine whether or not to use the first and second reflected waves for object detection based on whether or not the reflection intensities of the first and second reflected waves are less than a third threshold value that is set to a value greater than the automatic threshold value in order to detect a single reflected wave. The object detection device according to claim 2 .

4. 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 for calculating a position of the object relative to the vehicle based on the reflected wave; a determination unit that determines whether or not to use the reflected wave for object detection based on a calculation result of the calculation unit, The calculation unit is When the reflected waves exceed an automatic threshold value set based on background noise and include a first reflected wave reflected by a first object and a second reflected wave reflected by a second object, determining a coordinate of the first object relative to the vehicle based on the first reflected wave as a first coordinate; determining a coordinate of the second object relative to the vehicle based on the second reflected wave as a second coordinate; determining a position difference between the first and second coordinates; The determination unit is When the position difference between the first and second coordinates is equal to or smaller than a second threshold, it is determined that the first and second reflected waves are to be used for object detection. Object detection device.

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