Object detection device

Abstract

Provided is an object detection device capable of filtering unnecessary reflected waves and detecting important objects such as pedestrians even if the reflected waves are weak. An object detection device according to an embodiment is provided with: a calculation unit that determines the position of an object with respect to a vehicle on the basis of a reflected wave reflected by the object; and a determination unit that determines whether or not to use the reflected waves for object detection on the basis of the calculation result of the calculation unit, the calculation unit determining whether or not to use the reflected waves for object detection if the reflected waves include a first reflected wave that exceeds an automatic threshold value and is reflected by the first object and a second reflected wave that is reflected by the second object. The determination unit determines the distance between the first object and the vehicle on the basis of the first reflected wave and sets the distance as a first distance, determines the distance between the second object and the vehicle on the basis of the second reflected wave and sets the distance as a second distance, and determines the difference between the first distance and the second distance. The first reflected wave and the second reflected wave are used for object detection.

Description

Technical Field

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

[0002] There is an object detection device that detects an object in front of a vehicle while the vehicle is traveling and warns the driver. For example, in the technology of Patent Document 1, a moving average value obtained by CFAR (Constant False Alarm Rate) processing is subtracted from a received signal of a distance measuring unit that transmits and receives ultrasonic waves, and the inconsistency of each short interval is calculated and used as an adaptive threshold. As a result, the threshold can be adaptively changed to match the amplitude of unnecessary reflected waves from the road surface.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2021-001811

[0004] However, if the threshold is lowered as in Patent Document 1, undesired objects such as low steps that do not hinder the running of the vehicle may also be detected. Summary of the invention

[0005] The present invention has been made in view of the above circumstances, and provides an object detection device that filters unnecessary reflected waves and can detect important objects such as pedestrians even with weak reflected waves.

[0006] In order to solve the above-mentioned problems and achieve the objectives, an object detection device according to an embodiment includes: a detection unit that detects that a distance measuring unit that is provided on a vehicle and transmits and receives sound waves or radio waves receives a reflected wave reflected by an object; a calculation unit that obtains a position of the object relative to the vehicle based on the reflected wave; and a determination unit that determines whether to use the reflected wave for object detection based on a calculation result of the calculation unit, wherein the calculation unit obtains a distance of the first object relative to the vehicle based on the first reflected wave and sets the distance as a first distance, obtains a distance of the second object relative to the vehicle based on the second reflected wave and sets the distance as a second distance, and obtains a difference between the first distance and the second distance, and the determination unit uses the first reflected wave and the second reflected wave for object detection when the difference between the first distance and the second distance is less than the first threshold value.

[0007] The object detection device according to the embodiment can filter unnecessary reflected waves and detect important objects such as pedestrians even with weak reflected waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a top view of a vehicle equipped with the object detection device according to the embodiment.

[0009] Figure 2 This is a block diagram showing an example of the overall configuration of an object detection system according to an embodiment.

[0010] Figure 3 This is a block diagram showing an example of a functional structure of an object detection device according to an embodiment.

[0011] Figure 4 This is a schematic diagram for explaining an example of an operation of object detection performed by the object detection device according to the embodiment.

[0012] Figure 5 This is a schematic diagram for explaining an example of an operation of object detection performed by the object detection device according to the embodiment.

[0013] Figure 6 This is a schematic diagram for explaining an example of an operation of object detection performed by the object detection device according to the embodiment.

[0014] Figure 7 This is a schematic diagram for explaining an example of an operation of object detection performed by the object detection device according to the embodiment.

[0015] Figure 8 This is a schematic diagram for explaining an example of an operation of object detection performed by the object detection device according to the embodiment.

[0016] Fig. 9 This is a flowchart showing an example of a procedure of an object detection process performed by the object detection device according to the embodiment.

[0017] Fig.10 This is a flowchart showing an example of a procedure of an object detection process performed by an object detection device according to another modified example of the embodiment.

[0018] Fig.11 This is a flowchart showing an example of a procedure of an object detection process performed by an object detection device according to another modified example of the embodiment.

[0019] Description of Reference Numerals

[0020] 10... vehicle; 14... distance measuring unit; 20... object detecting device; 201... detection unit; 202... operation unit; 203... determination unit; 204... instruction unit; 205... storage unit. DETAILED DESCRIPTION

[0021] The same components in the following exemplary embodiments and the like are denoted by common reference numerals, and duplicate descriptions are appropriately omitted.

[0022] (Example of vehicle structure)

[0023] Figure 1 It is a plan view of a vehicle 10 equipped with the object detection device 20 according to the embodiment. Figure 1 The front, rear, left, and right of the vehicle 10 in FIG. 1 represent directions when viewed from a driver's seat of the vehicle 10 .

[0024] The vehicle 10 of the embodiment may be, for example, an internal combustion engine vehicle using an internal combustion engine as a driving source, an electric vehicle or a fuel cell vehicle using an electric motor as a driving source, or a hybrid vehicle using both of them as driving sources.

[0025] In addition, the vehicle 10 can be equipped with various transmission devices and various systems, components and other devices required to drive the internal combustion engine or the electric motor. In addition, the form, number and layout of the devices related to the driving of the wheels 13 in the vehicle 10 can be set in various ways.

[0026] like Figure 1 As shown, the vehicle 10 includes a vehicle body 12, a plurality of wheels 13, and a plurality of distance measuring units 14a to 141. When it is not necessary to distinguish the distance measuring units 14a to 141, they are simply described as the distance measuring unit 14.

[0027] The vehicle body 12 constitutes a vehicle room for passengers to sit in. A plurality of wheels 13 and a plurality of distance measuring units 14 are mounted on the vehicle body 12 . Figure 1 In the example of FIG. 1 , the vehicle body 12 includes four wheels 13 and twelve distance measuring units 14. However, the number of distance measuring units 14 mounted on the vehicle body 12 is arbitrary.

[0028] The four wheels 13 are provided at the front, rear, left, and right of the vehicle body 12. The two front wheels 13 function as, for example, steering wheels, and the two rear wheels 13 function as, for example, drive wheels.

[0029] The distance measuring unit 14 is, for example, a sonar that is provided at the periphery of the vehicle 10 and transmits sound waves such as ultrasonic waves and receives reflected waves reflected by objects such as obstacles existing around the vehicle 10. Alternatively, the distance measuring unit 14 may be a radar or millimeter wave radar that transmits electromagnetic waves such as lasers.

[0030] The distance measuring unit 14 outputs the information of the received reflected wave to the object detection device 20. The distance measuring unit 14 collects, for example, the time from the transmission of the ultrasonic wave to the reception of the reflected wave, that is, the response time, as information for determining the distance between the object and the vehicle 10. The object detection device 20 can detect the presence or absence of obstacles and the like around the vehicle 10 and the distance to the obstacles based on the information collected by the distance measuring unit 14.

[0031] Furthermore, when the distance measuring unit 14 receives a plurality of reflected waves reflected from a plurality of positions of the object in response to one transmission of ultrasonic waves, the distance measuring unit 14 may include only the response time of the earliest received reflected wave in the above information.

[0032] The distance measuring units 14a to 14d are provided at the front portion of the vehicle body 12. The distance measuring units 14b and 14c of the distance measuring units 14a to 14d are also called front sonars and are provided at the front end portion of the vehicle 10. The distance measuring units 14b and 14c receive reflected waves from an object in front of the vehicle 10. In addition, the distance measuring units 14a and 14d are also called corner sonars and are provided at the corner portions of the front portion of the vehicle 10. The distance measuring units 14a and 14d receive reflected waves from an object outside the front of the vehicle 10.

[0033] The distance measuring units 14e to 14h are provided at the rear of the vehicle body 12. The distance measuring units 14f and 14g of the distance measuring units 14e to 14h 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 outside the rear of the vehicle 10.

[0034] The distance measuring units 14i to 14l are also called side sonars, and are provided on the side of the vehicle body 12. The distance measuring units 14i and 14j of the distance measuring units 14i to 14l are provided on the side of the front of the vehicle 10. The distance measuring units 14k and 14l are provided on the side of the rear of the vehicle 10. The distance measuring units 14i to 14l receive reflected waves from objects on the side of the vehicle 10.

[0035] Furthermore, the vehicle 10 may be provided with a plurality of imaging units capable of imaging the periphery of the vehicle 10 in addition to the plurality of distance measuring units 14 a to 14 l described above.

[0036] (Configuration example of object detection system)

[0037] Figure 22 is a block diagram showing an example of the overall configuration of object detection system 200 according to the embodiment. Object detection system 200 is mounted on vehicle 10 , for example, detects an object based on information output from distance measuring unit 14 , and controls vehicle 10 based on the object detection result.

[0038] like Figure 2 As shown, the object detection system 200 includes an object detection device 20 , a plurality of distance measuring units 14 , a brake system 121 , a buzzer 122 , and an engine 123 .

[0039] The object detection device 20 is connected to the plurality of distance measuring units 14 via LIN (Local Interconnect Network) as an in-vehicle network. In addition, the object detection device 20 is connected to the brake system 121, buzzer 122, engine 123, and shift sensor 124 via CAN (Controller Area Network) as an in-vehicle network.

[0040] Each distance measuring unit 14 includes a vibrator 141 formed by a piezoelectric element or the like and an amplifier (not shown) and the like, and is configured to be able to transmit and receive ultrasonic waves through the vibration of the vibrator 141. Specifically, the distance measuring unit 14 transmits ultrasonic waves generated in response to the vibration of the vibrator 141, and detects the vibration of the vibrator 141 generated 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 vibrator 141 is converted into an electrical signal, and based on the electrical signal, the flight time (TOF: Time of Flight) of the ultrasonic wave corresponding to the distance from the distance measuring unit 14 to the object OB, the Doppler shift information corresponding to the relative speed between the vehicle 10 and the object OB, and the like can be obtained.

[0041] in addition, Figure 2 In the example shown, a configuration is shown in which both transmission and reception are performed using a single transducer 141, but the configuration of the distance measuring unit 14 is not limited thereto. For example, a configuration in which the transmission side and the reception side are separated may be used, such as a configuration in which a transmission transducer and a reception transducer are provided separately.

[0042] 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 the information from the distance measuring unit 14 and performs control of the vehicle 10. The object detection device 20 can receive various information from the distance measuring unit 14 via LIN. In addition, the object detection device 20 controls the brake system 121 and the engine 123 by sending a control signal via CAN, and can also output a sound to the buzzer 122.

[0043] The object detection device 20 includes a CPU (Central Processing Unit) 21 , a ROM (Read Only Memory) 22 , a RAM (Random Access Memory) 23 , and an SSD (Solid State Drive) 24 .

[0044] The CPU 21 can perform various calculations and controls such as object detection, determination of interference with an object, and output of an alarm to a buzzer 122. The ROM 22 is a nonvolatile storage device. The ROM 22 stores a program in advance. The CPU 21 can read the program stored in the ROM 22 and perform calculations according to the program.

[0045] RAM 23 temporarily stores various data used in calculations of CPU 21. SSD 24 is a rewritable nonvolatile storage unit, and can store data even when the power of object detection device 20 is turned off.

[0046] In addition, the CPU 21, ROM 22, and RAM 23 may be integrated in the same package. In addition, the object detection device 20 may also be a structure that uses other logic operation processors or logic circuits such as DSP (Digital Signal Processor) instead of CPU 21. In addition, a HDD (Hard Disk Drive) may be provided instead of SSD 24, and the SSD 24 or HDD may be provided separately from the object detection device 20.

[0047] The brake system 121 is, for example, an ABS (Anti-lock Brake System) that suppresses brake locking, an anti-skid device (ESC: Electronic Stability Control) that suppresses the side slip of the vehicle 10 when turning, an electric brake system that enhances the braking force to perform brake assist, BBW (Brake By Wire), etc.

[0048] The engine 123 is a prime mover that drives the vehicle 10 .

[0049] The buzzer 122 is provided inside the vehicle 10 and outputs an alarm.

[0050] Figure 3 1 is a block diagram showing an example of the functional structure of the object detection device 20 according to the embodiment. Figure 3As shown, the object detection device 20 includes a detection unit 201, a calculation unit 202, a determination unit 203, an instruction unit 204, and a storage unit 205 as functional units.

[0051] These functional units are realized by, for example, the CPU 21 reading a program stored in a storage device such as the ROM 22, expanding it on the RAM 23, and executing it. In addition, some or all of these functional units may be constituted by hardware such as a circuit including an ASIC (Application Specific Integrated Circuit).

[0052] The detection unit 201 acquires information related to the transmission and reception of ultrasonic waves by the distance measuring unit 14. In addition, when a reflected wave exceeding an automatic threshold value is received from a received signal based on the distance measuring unit 14, the detection unit 201 detects the reflected wave. The automatic threshold value is a background noise calculated based on the reflected wave received by the distance measuring unit 14. As a specific calculation method of the automatic threshold value, at least one of the common algorithms used in CFAR processing can be used.

[0053] The calculation unit 202 calculates the position of the object relative to the vehicle 10 based on the reflected waves detected by the detection unit 201. In addition, when multiple reflected waves exceeding the automatic threshold are detected at the same time, the distances between the objects respectively calculated based on these reflected waves are calculated. In addition, the coordinates of each object relative to the vehicle 10 are calculated based on these reflected waves, and the position differences of these objects are calculated.

[0054] The determination unit 203 determines whether or not to use the reflected wave detected by the detection unit 201 for object detection in the object detection device 20 .

[0055] Here, among obstacles that may hinder the travel of the vehicle 10, poles and steps above a predetermined height have relatively simple appearances, and it is generally believed that a relatively strong single reflected wave based on single reflection is often returned. On the other hand, pedestrians and bicycles have complex shapes, and relatively weak multiple reflected waves based on multiple reflections are often returned.

[0056] Therefore, the determination unit 203 determines whether multiple reflected waves with intensities exceeding the automatic threshold are detected at the same time. If multiple reflected waves are detected, it determines whether the distances and position differences between the multiple objects determined by the above-mentioned operation unit 202 are within the specified threshold based on these reflected waves.

[0057] If the distance and position difference between the objects are within the specified threshold, it means that the objects are sufficiently close to each other and they are not considered to be multiple independent objects, but are equivalent to different parts of a single object such as a pedestrian or a bicycle. In other words, the above-mentioned reflected waves detected in multiples are considered to be multiple reflections from multiple parts of a single object.

[0058] On the other hand, when a single reflected wave exceeding the automatic threshold is detected, it is highly likely that it is a single reflection from an object with a simple appearance such as a pole. In addition, even when at least one of the distance and position difference between objects determined from a plurality of reflected waves exceeds the respective corresponding thresholds, it is possible that the reflected waves are generated by single reflections from a plurality of objects with a simple appearance.

[0059] Therefore, when the intensity of such a reflected wave is equal to or higher than a threshold value suitable for a single reflected wave, the determination unit 203 determines to use the reflected wave for object detection.

[0060] When the intensity of the reflected waves described above is less than the threshold applied to the single reflected waves, it is considered that the reflected waves are noises from objects such as unevenness of the road surface that do not 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.

[0061] When the position of the object calculated by the calculation unit 202 is in a positional relationship that may interfere with the vehicle 10 after a predetermined time, the command unit 204 controls various parts of the vehicle 10 to avoid interference between the vehicle 10 and the object based on the reflected waves due to multiple reflections or single reflections.

[0062] More specifically, the command unit 204 sends a command to the buzzer 122 to output a warning to the driver. In addition, the command unit 204 sends a command to the brake system 121 to apply the brakes. In this way, the vehicle 10 can be decelerated or stopped.

[0063] Furthermore, the command unit 204 may send a command to the engine 123 to reduce the output of the engine 123 instead of the braking by the brake system 121, or send a command to the engine 123 to reduce the output of the engine 123 in addition to the braking by the brake system 121. In this way, the vehicle 10 can also be decelerated or stopped.

[0064] The storage unit 205 stores control programs and various control parameters necessary for the operation of the object detection device 20. The storage unit 205 also stores a plurality of threshold values ​​used by the determination unit 203 for various determinations.

[0065] (Operation example of object detection device)

[0066] Next, use Figures 4 to 9 , an operation example of the object detection device 20 according to the embodiment is described. Figures 4 to 9 This is a schematic diagram for explaining an example of the operation of object detection performed by the object detection device 20 according to the embodiment.

[0067] Figure 4 FIG. 2 shows a situation where the plurality of 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 reflected waves when the vehicle 10 is moving forward. Figure 4 As shown, the pedestrian M has a complex shape, and therefore the transmitted ultrasonic wave is multiply reflected and received by the distance measuring unit 14 . Figure 4 In the example of , the ultrasonic waves reaching the left hand, right hand, left leg, right leg and torso of the pedestrian M generate reflected waves RFa, RFb, RFc, RFd and RFe respectively.

[0068] Figure 5 An example of a reception signal of the distance measuring unit 14 detected by the detection unit 201 in the above case is shown. Figure 5 The horizontal axis is the distance from the vehicle 10, and the vertical axis is the reflection intensity of the received signal. In the object detection device 20 of the embodiment, as described above, the 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 less than the automatic threshold are regarded as background noise such as unevenness of the road surface and are filtered out.

[0069] Figure 5 In the example of , the reflected wave RFa reflected by the left hand and the reflected wave RFb reflected by the right hand among the reflected waves RFa to RFe from the parts of the pedestrian M 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 are detected.

[0070] like Figure 6 As shown, when a plurality of reflected waves RFa and RFb exceeding the automatic threshold are detected, the operation unit 202 obtains the distance of the object determined based on the reflected wave RFa relative to the vehicle 10. In addition, the operation unit 202 obtains the distance of the object determined based on the reflected wave RFb relative to the vehicle 10. In this way, the distance of each object relative to the vehicle 10 can be obtained based on, for example, a received signal of one distance measuring unit 14. Based on the above, the distance of the left hand and the right hand of the pedestrian M relative to the vehicle 10 at a predetermined time is obtained.

[0071] In addition, the reflected waves RFa and RFb are examples of the first reflected wave and the second reflected wave, respectively, the left hand and the right hand of the pedestrian M are examples of the first object and the second object, and the distances of the left hand and the right hand of the pedestrian M relative to the vehicle 10 are examples of the first distance and the second distance, respectively.

[0072] The calculation unit 202 further obtains the difference D between the distances from the vehicle 10 to the objects corresponding to the reflected waves RFa and RFb. Thus, the distance between the left hand and the right hand of the pedestrian M is obtained. The determination unit 203 determines whether the difference D between the distances calculated by the calculation unit 202 is less than a predetermined threshold value.

[0073] The threshold value at this time is preset based on the average size of objects that are prone to multiple reflections, such as pedestrians M and bicycles. More specifically, the threshold value is set based on the two-dimensional size of the object such as pedestrians M that is consistent with the traveling direction of the vehicle 10. In addition, the threshold value used for the distance difference D calculated by the calculation unit 202 is an example of the first threshold value.

[0074] like Figure 7 As shown, the operation unit 202 also obtains the coordinates of the object determined based on the reflected wave RFa relative to the vehicle 10. In addition, the operation unit 202 obtains the coordinates of the object determined based on the reflected wave RFb relative to the vehicle 10. In this way, the coordinates of each object relative to the vehicle 10 can be obtained based on the received signals of the multiple distance measuring units 14, for example, using triangulation or the like.

[0075] Through the above calculation, the three-dimensional position coordinates of the left and right hands of the pedestrian M at a predetermined time relative to the vehicle 10 are obtained. The coordinates of the left and right hands of the pedestrian M relative to the vehicle 10 are examples of the first coordinates and the second coordinates, respectively.

[0076] The calculation unit 202 also obtains the position difference P of the coordinates of each object corresponding to the reflected waves RFa and RFb relative to the vehicle 10. Thus, the position difference between the left hand and the right hand of the pedestrian M is obtained. In other words, the position difference P can be expressed as, for example, the two coordinates are separated by a distance x in the X direction and a distance y in the Y direction. The determination unit 203 determines whether the position difference P calculated by the calculation unit 202 is less than a predetermined threshold value.

[0077] The threshold value at this time is also preset based on the average size of objects that are prone to multiple reflections, such as pedestrians M and bicycles. More specifically, the threshold value is set based on the three-dimensional size represented by the XY coordinates of the object such as pedestrians M relative to the vehicle 10. In addition, the threshold value used for the position difference P calculated by the calculation unit 202 is an example of the second threshold value.

[0078] If a plurality of reflected waves exceeding the automatic threshold are detected, and the distances and position differences between the plurality of objects based on the reflected waves are within the predetermined threshold, the reflected waves are considered to be multiple reflections from a single object having a complex shape such as the pedestrian M. Therefore, the reflected wave determination unit 203 performs determination for object detection even if the reflected waves are weak.

[0079] On the other hand, when a single reflected wave exceeding the automatic threshold is detected, as described above, there is a possibility that it is a single reflection from an object having a simple shape such as a pole. In addition, when multiple reflected waves exceeding the automatic threshold are detected, even if at least one of the distance and position difference between the objects determined based on these reflected waves exceeds the corresponding threshold, there is a possibility that reflected waves based on single reflections from multiple objects are detected at the same time.

[0080] like Figure 8 As shown, the determination unit 203 determines whether such a reflected wave is less than a predetermined threshold value set in advance for detecting a single reflection.

[0081] The intensity of the reflected wave based on a single reflection is generally higher than the reflected wave based on multiple reflections from the pedestrian M and the like. Therefore, the threshold value at this time is set based on the average intensity of the reflected wave based on the single reflection. In addition, the intensity of the reflected wave based on the single reflection may vary depending on the distance from the vehicle 10, and therefore, as the threshold value applied to the single reflection, a different value is set depending on the distance from the vehicle 10. In addition, the above threshold value set for detecting the single reflected wave is an example of the third threshold value.

[0082] The determination unit 203 determines whether to use the reflected wave for object detection when the single reflected wave exceeding the automatic threshold is equal to or greater than the threshold suitable for the single reflected wave. On the other hand, when the single reflected wave exceeding the automatic threshold is less than the threshold suitable for the single reflected wave, the determination unit 203 determines not to use the reflected wave for object detection.

[0083] Furthermore, even when at least one of the distances and position differences between objects determined based on a plurality of reflected waves exceeds the respective corresponding thresholds, there is a possibility that reflected waves based on single reflections from a plurality of objects are detected at the same time. Therefore, in such a case, the determination unit 203 also determines whether or not the threshold for a single reflected wave is less than the above threshold for each of these reflected waves.

[0084] When any one of the multiple reflected waves exceeding the automatic threshold is greater than the threshold suitable for a single reflected wave, the determination unit 203 determines whether to use the reflected wave for object detection. At this time, when some or all of the multiple reflected waves have intensities greater than the threshold, it means that the number of independent objects equal to the number of detected reflected waves is detected.

[0085] On the other hand, if any of the plurality of reflected waves exceeding the automatic threshold value is less than the threshold value suitable for a single reflected wave, the determination unit 203 determines not to use the reflected wave for object detection. In this case, the reflected wave is filtered out.

[0086] As described above, the operation of the object detection device 20 according to the embodiment at a predetermined time is completed.

[0087] (Processing Example of Object Detection Device)

[0088] Next, use Fig. 9 , an example of object detection processing performed by the object detection device 20 of the embodiment is described. Fig. 9 1 is a flowchart showing an example of a procedure of an object detection process performed by the object detection device 20 according to the embodiment.

[0089] like Fig. 9 As shown, for example, when the vehicle 10 starts to travel at a predetermined speed, the object detection device 20 starts the object detection process (step S101). Correspondingly, the detection unit 201 obtains the received signal from the distance measuring unit 14 and monitors whether a reflected wave exceeding the automatic threshold is detected (step S102). When a reflected wave exceeding the automatic threshold is not detected (step S102: No), the process at this moment ends and the process proceeds to step S113.

[0090] When the detection unit 201 detects a reflected wave exceeding the automatic threshold value (step S102 : Yes), the determination unit 203 determines whether or not two or more reflected waves have been detected (step S103 ).

[0091] When the determination unit 203 determines that two or more reflected waves are detected (step S103 : Yes), the calculation unit 202 obtains the difference in distances between the plurality of objects specified based on the reflected waves (step S104 ).

[0092] The determination unit 203 determines whether the difference in distances between the plurality of objects obtained by the calculation unit 202 is less than or equal to the threshold value corresponding thereto (step S105). When the determination unit 203 determines that the difference in distances between the plurality of objects is less than or equal to the threshold value specified above (step S105: yes), the calculation unit 202 obtains the coordinates of the plurality of objects determined based on the reflected waves relative to the vehicle 10, and obtains the position difference between the objects based on the coordinates (step S106).

[0093] The determination unit 203 determines whether the position difference of the plurality of objects obtained by the calculation unit 202 is less than the corresponding threshold value (step S107). If the position difference of the plurality of objects is less than the predetermined threshold value (step S107: Yes), the determination unit 203 determines whether to use the reflected waves for object detection (step S108).

[0094] On the other hand, when a single reflected wave is detected by the detection unit 201 (step S103: No), when a plurality of reflected waves are detected by the detection unit 201 but the difference in distances of a plurality of objects based on them exceeds the threshold value corresponding thereto (step S105: No), or when the difference in positions of a plurality of objects based thereon exceeds the threshold value corresponding thereto (step S107: No), the determination unit 203 determines whether or not the detected single or multiple reflected waves are less than the threshold value suitable for a single reflected wave (step S109).

[0095] When any of the reflected waves is less than the threshold value of the single reflected wave (step S109: Yes), the determination unit 203 determines not to use the reflected wave for object detection, thereby filtering out the reflected wave (step S110). When any of the reflected waves is greater than the threshold value of the single reflected wave (step S109: No), the determination unit 203 determines to use the reflected wave for object detection (step S108).

[0096] If there are reflected waves determined to be used for object detection, the determination unit 203 determines whether control of the vehicle 10 is necessary based on the positional relationship of the object with respect to the vehicle 10 based on the reflected waves (step S111 ).

[0097] When the object corresponding to the reflected wave is located at a position that may interfere with the vehicle 10 after a predetermined time, for example, the determination unit 203 determines that the vehicle 10 needs to be controlled in order to avoid interference with the object (step S111: Yes). The instruction unit 204 controls various parts of the vehicle 10 based on such a determination result (step S112).

[0098] At this time, the command unit 204 outputs a warning from the buzzer 122 in the vehicle cabin to call the driver's attention, and performs at least one of braking the vehicle 10 with the brake system 121 and decelerating the vehicle 10 by reducing the output of the engine 123 .

[0099] If the object corresponding to the reflected wave is located at a position unlikely to interfere with the vehicle 10 after a predetermined time, for example, the determination unit 203 determines that control of the vehicle 10 is unnecessary (step S111 : No), and skips the process of step S112 .

[0100] If the vehicle 10 is traveling at a predetermined speed or higher, the object detection device 20 continues the object detection process (step S113: No), and repeats the process from step S102. If the vehicle 10 is stopped, the object detection process ends (step S113).

[0101] Based on the above, the object detection process performed by the object detection device 20 according to the embodiment ends.

[0102] (Summary)

[0103] An object detection device that detects objects around a vehicle filters out reflected waves from objects that do not hinder vehicle travel, such as unevenness on the road surface, as background noise, and therefore uses an automatic threshold value obtained by, for example, CFAR processing.

[0104] However, when filtering and removing by automatic thresholding, for example, weak reflected waves generated by multiple reflections from objects with complex shapes such as pedestrians may be filtered out. Thus, for example, reflected waves from pedestrians and the reflected waves generated by the above-mentioned background noise may be detected at relatively close intensities, making it difficult to distinguish them.

[0105] According to the object detection device 20 of the embodiment, when the reflected waves include two or more reflected waves exceeding the automatic threshold value set based on the background noise, the calculation unit 202 calculates the distance of the object corresponding to the vehicle 10 based on one reflected wave, calculates the distance of the object corresponding to the vehicle 10 based on the other reflected wave, and calculates the difference between the distances. When the difference between the distances is less than the corresponding predetermined threshold value, the determination unit 203 uses the reflected waves for object detection.

[0106] According to the above, it is possible to distinguish whether these reflected waves are multiple reflections from different parts of an object, and whether they should be filtered out as background noise, etc. Therefore, unnecessary reflected waves can be filtered and important objects such as pedestrians can be detected even with weak reflected waves.

[0107] According to the object detection device 20 of the embodiment, when the reflected waves include two or more reflected waves exceeding the automatic threshold value set based on the background noise, the calculation unit 202 obtains the coordinates of the object corresponding to the one reflected wave relative to the vehicle 10, obtains the coordinates of the object corresponding to the other reflected wave relative to the vehicle 10, and obtains the position difference based on these coordinates. The determination unit 203 uses these reflected waves for object detection when the position difference based on the above coordinates is less than the corresponding threshold value in addition to the above distance difference being less than the corresponding threshold value.

[0108] As described above, by determining the positional differences between the objects in addition to the distance differences between the objects, it is possible to more accurately discriminate whether the reflected waves are multiple reflections from different locations of one object.

[0109] According to the object detection device 20 of the embodiment, the determination unit 203 utilizes these reflected waves for object detection when the difference in distances between the above-mentioned multiple objects exceeds the corresponding above-mentioned threshold value or the position difference in coordinates between the above-mentioned multiple objects exceeds the corresponding above-mentioned threshold value, and when the reflection intensity of these reflected waves is less than the threshold value set to a value larger than the automatic threshold value in order to detect a single reflected wave.

[0110] Thus, even when there are actually multiple independent objects, these objects can be detected. In addition, by clearly distinguishing that the multiple detected reflected waves are not reflected waves based on multiple reflections and using the threshold value applied to the single reflected wave, it can be determined whether these reflected waves should be filtered out as background noise or the like.

[0111] In addition, in the above-mentioned embodiment, when a plurality of reflected waves are detected at the same time, the calculation unit 202 obtains the distance difference and the position difference to the plurality of objects based on these reflected waves, and the determination unit 203 determines whether these distance difference and position difference are less than or equal to the corresponding threshold values. However, it is also possible to determine whether the plurality of reflected waves detected at the same time are based on multiple reflections based on only one of the distance difference and the position difference to the plurality of objects. Fig.10 as well as Fig.11 An example of processing in such a case is shown.

[0112] Fig.10 This is a flowchart showing an example of a procedure of an object detection process performed by an object detection device according to another modified example of the embodiment. Fig.10 The processing of steps S201 to S205 and the processing of steps S208 to S213 are respectively the same as those of the above-mentioned embodiment. Fig. 9The processing of steps S101 to S105 and the processing of steps S108 to S113 correspond to each other. Fig.10 In the example of , when a plurality of reflected waves are detected at the same time, determination is not made on the positional differences of the plurality of objects, but whether the reflected waves are based on multiple reflections is determined.

[0113] Obtaining three-dimensional coordinates for a plurality of objects and determining positional differences between the plurality of objects based on the three-dimensional coordinates may increase the internal processing load of the object detection device. Fig.10 In the example shown, such processing is not performed, so the load on the object detection device is reduced, and it is possible to more easily determine whether to perform filtering and removal on a plurality of reflected waves.

[0114] Fig.11 This is a flowchart showing an example of a procedure of an object detection process performed by an object detection device according to another modified example of the embodiment. Fig.11 The processing of steps S301 to S303 and the processing of steps S306 to S313 are respectively the same as those of the above-mentioned embodiment. Fig. 9 The processing of steps S101 to S103 and the processing of steps S106 to S113 correspond to each other. Fig.11 In the example of , when a plurality of reflected waves are detected at the same time, determination is not made on the difference in distances to the plurality of objects, but whether or not these reflected waves are based on multiple reflections is determined.

[0115] By obtaining three-dimensional coordinates for a plurality of objects and determining the positional differences of the plurality of objects based on the three-dimensional coordinates, the proximity between the plurality of objects can be determined more accurately than when the difference in two-dimensional distances between the plurality of objects is used. Therefore, even if the difference in two-dimensional distances between the plurality of objects is not determined, sufficient determination accuracy can be obtained.

[0116] In the above-mentioned embodiment, the judgment is performed by using both the difference in two-dimensional distance and the difference in three-dimensional position of a plurality of objects. Fig.10 as well as Fig.11 The judgment accuracy is further improved compared with the example.

[0117] In this way, when determining whether a plurality of reflected waves are reflected waves based on multiple reflections, it is possible to arbitrarily determine which combination to use between the two-dimensional distance difference and the three-dimensional position difference for a plurality of objects according to the type, specification, and driving environment of the vehicle 10 .

Claims

1. An object detection device, characterized in that: have: a detection unit that detects that a distance measuring unit that is provided on the vehicle and transmits and receives sound waves or radio waves receives a reflected wave reflected by an object; a calculation unit for obtaining a position of the object relative to the vehicle based on the reflected wave; as well as a determination unit that determines whether to use the reflected wave for object detection based on the calculation result of the calculation unit, When the reflected wave 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 and sets the distance as a first distance, calculates the distance of the second object relative to the vehicle based on the second reflected wave and sets the distance as a second distance, and calculates a difference between the first distance and the second distance. The determination unit uses the first reflected wave and the second reflected wave for object detection when the difference between the first distance and the second distance is equal to or smaller than a first threshold value.

2. The object detection device according to claim 1, characterized in that: The calculation unit calculates the difference between the first distance and the second distance, calculates the coordinates of the first object relative to the vehicle based on the first reflected wave and sets the coordinates as the first coordinates, calculates the coordinates of the second object relative to the vehicle based on the second reflected wave and sets the coordinates as the second coordinates, and calculates the position difference between the first coordinate and the second coordinate. The determination unit uses the first reflected wave and the second reflected wave for object detection when the difference between the first distance and the second distance is equal to or less than the first threshold value and the position difference between the first coordinate and the second coordinate is equal to or less than a second threshold value.

3. The object detection device according to claim 2, characterized in that: The determination unit uses the first reflected wave and the second reflected wave for object detection when the difference between the first distance and the second distance exceeds the first threshold or the position difference between the first coordinate and the second coordinate exceeds the second threshold, and when the reflection intensity of the first reflected wave and the second reflected wave is less than the third threshold set to a value larger than the automatic threshold in order to detect a single reflected wave.

4. An object detection device, characterized in that: have: a detection unit that detects that a distance measuring unit that is provided on the vehicle and transmits and receives sound waves or radio waves receives a reflected wave reflected by an object; a calculation unit for obtaining a position of the object relative to the vehicle based on the reflected wave; as well as a determination unit that determines whether to use the reflected wave for object detection based on the calculation result of the calculation unit, The calculation unit calculates the coordinates of the first object relative to the vehicle based on the first reflected wave and sets the coordinates as the first coordinates, calculates the coordinates of the second object relative to the vehicle based on the second reflected wave and sets the coordinates as the second coordinates, and calculates the position difference between the first coordinate and the second coordinates, when the reflected wave includes a first reflected wave reflected by a first object and a second reflected wave reflected by a second object, which is a reflected wave exceeding an automatic threshold value set based on background noise. The determination unit uses the first reflected wave and the second reflected wave for object detection when the position difference between the first coordinate and the second coordinate is equal to or smaller than a second threshold value.

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