Object detection device

Abstract

An object detection device detects an obstacle present in the periphery of a moving body on the basis of a time-series change in the intensity of a reflected wave generated by reflection of a transmission wave transmitted from the moving body by an object, the object detection device being provided with: a threshold value calculation unit; calculating a variation threshold value that varies with the movement of the moving body on the basis of the average value of the movement of the intensity of the reflected waves; and a determination unit that determines that an obstacle is present when the intensity of the reflected wave is greater than a predetermined fixed threshold value and variation threshold value.

Description

Technical Field

[0001] This invention relates to an object detection device. Background Technology

[0002] Object detection devices that detect obstacles around moving objects, such as vehicles, using time-of-flight (TOF) and Doppler shift information obtained through transceiver methods like ultrasound, are employed to detect these obstacles. In these devices, a constant false alarm rate (CFAR) is used to suppress noise from reflected waves from non-detectable objects (such as road surfaces). Through CFAR processing, the threshold used to determine whether an object reflecting a reflected wave is an obstacle is appropriately adjusted based on road conditions and other factors, using a moving average of the intensity of the reflected wave that varies over time.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-206011 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] While the CFAR processing described above can generally suppress the effects of noise, it can still be susceptible to noise depending on the situation. For example, if the road surface on which the moving object is traveling is smooth, the threshold is set relatively low. Therefore, if a small step or other non-obstacle suddenly appears on such a surface, the intensity of the reflected wave from that non-obstacle can easily exceed the threshold. In this case, regardless of whether an obstacle actually exists, it may be mistakenly identified as present.

[0008] The present invention is made in view of the above circumstances, and provides an object detection device capable of suppressing false detection of obstacles.

[0009] Technical solutions for solving the problem

[0010] One aspect of the present invention provides an object detection device that detects obstacles around a moving body based on the temporal variation of the intensity of a reflected wave generated by the reflection of a transmitted wave from the moving body. The object detection device includes: a threshold calculation unit that calculates a variable threshold that varies with the movement of the moving body based on a moving average of the intensity of the reflected wave; and a determination unit that determines the presence of an obstacle when the intensity of the reflected wave is greater than a preset fixed threshold and a variable threshold.

[0011] Invention Effects

[0012] According to the present invention, an object detection device is provided that can suppress false detection of obstacles. Attached Figure Description

[0013] Figure 1 This is a diagram illustrating an example of the structure of the vehicle according to the first embodiment.

[0014] Figure 2 This is a diagram illustrating an example of the structure of the vehicle control system according to the first embodiment.

[0015] Figure 3 This is a diagram illustrating an example of a distance calculation method based on the Time-of-Flight (TOF) method according to the first embodiment.

[0016] Figure 4 This is a diagram illustrating an example of the functional structure of the object detection device according to the first embodiment.

[0017] Figure 5 This is a diagram illustrating an example of the CFAR processing involved in the first embodiment.

[0018] Figure 6 This is a diagram illustrating an example of a fixed threshold involved in the first embodiment.

[0019] Figure 7 This is a diagram illustrating an example of the CFAR threshold in the presence of obstacles in the first embodiment.

[0020] Figure 8 This is a diagram illustrating an example of the CFAR threshold in the absence of obstacles in the first embodiment.

[0021] Figure 9 This is a diagram illustrating an example of the relationship between the envelope and the fixed threshold and the CFAR threshold in the presence of obstacles in the first embodiment.

[0022] Figure 10 This is a diagram illustrating an example of the relationship between the envelope and the fixed threshold and the CFAR threshold in the absence of obstacles in the first embodiment.

[0023] Figure 11 This is a flowchart illustrating an example of the processing in the object detection apparatus according to the first embodiment.

[0024] Figure 12 This is a diagram illustrating an example of the relationship between the envelope and the fixed threshold and the CFAR threshold in the presence of obstacles in the second embodiment.

[0025] Figure 13This is a diagram illustrating an example of the relationship between the envelope and the fixed threshold and the CFAR threshold in the second embodiment when there are no obstacles.

[0026] Figure 14 This is a flowchart illustrating an example of the processing in the object detection apparatus according to the second embodiment.

[0027] Figure 15 This is a diagram illustrating an example of the functional structure of the object detection device according to the third embodiment.

[0028] Figure 16 This is a diagram illustrating an example of the relationship between the envelope and the fixed threshold and the CFAR threshold in the presence of obstacles in the third embodiment.

[0029] Figure 17 This is a flowchart illustrating an example of the processing in the object detection apparatus according to the third embodiment. Detailed Implementation

[0030] The embodiments of the present invention will now be described with reference to the accompanying drawings. The structure of the embodiments described below, as well as the functions and effects brought about by the structure, are merely examples, and the present invention is not limited to the following description.

[0031] (First Implementation)

[0032] Figure 1 This diagram illustrates an example of the structure of the vehicle 1 according to the first embodiment. The vehicle 1 is an example of a moving body equipped with the object detection device of this embodiment. The object detection device of this embodiment is a device that detects obstacles existing around the vehicle 1 based on information such as TOF (Time of Flight) and Doppler displacement acquired through the transmission and reception of ultrasonic waves.

[0033] The object detection device of this embodiment includes a plurality of transceiver units 21A to 21L. Hereinafter, unless it is necessary to distinguish between the plurality of transceiver units 21A to 21L, it will sometimes be referred to as transceiver unit 21. Each transceiver unit 21 is installed on the vehicle body 2, which is an external component of the vehicle 1, and transmits ultrasonic waves to the outside of the vehicle body 2, and receives ultrasonic waves generated by reflections of these ultrasonic waves by objects located on the outside of the vehicle body 2. Hereinafter, ultrasonic waves transmitted from the transceiver unit 21 will sometimes be referred to as transmitted waves, and ultrasonic waves generated by reflections of transmitted waves by objects will sometimes be referred to as reflected waves.

[0034] exist Figure 1In the example shown, four transceivers 21A to 21D are arranged at the front end of the vehicle body 2, four transceivers 21E to 21H are arranged at the rear end, two transceivers 21I and 21J are arranged on the right side, and two transceivers 21K and 21L are arranged on the left side. Furthermore, the number and location of the transceivers 21 are not limited to this example.

[0035] Figure 2 This is a diagram illustrating an example of the structure of the vehicle control system 10 according to the first embodiment. The vehicle control system 10 performs processing for controlling the vehicle 1 based on information output from the object detection device 11. The vehicle control system 10 of this embodiment includes the object detection device 11 and the ECU 12.

[0036] The object detection device 11 includes a plurality of transceiver units 21 and a control unit 22. Each transceiver unit 21 includes an oscillator 31 constructed using a piezoelectric element or the like, an amplifier, etc., and transmits and receives ultrasonic waves through the vibration of the oscillator 31. Specifically, each transceiver unit 21 transmits ultrasonic waves generated corresponding to the vibration of the oscillator 31 as transmitted waves, and detects the vibration of the oscillator 31 caused by reflected waves from objects such as obstacles O and road surfaces G. The obstacle O is an object that should be detected among objects existing around the vehicle 1, such as other vehicles, road accessories, walls, people, curbs, wheel stops, etc. The vibration of the oscillator 31 is converted into an electrical signal, and the Time of Flight (TOF) corresponding to the distance from the transceiver unit 21 to the obstacle O and the Doppler displacement corresponding to the relative velocity between the vehicle 1 and the obstacle O can be obtained based on the electrical signal.

[0037] In addition, Figure 2 The example shown illustrates a structure where both the transmitting and receiving waves utilize a single transducer 31, but the structure of the transceiver unit 21 is not limited to this. For example, it could be a structure where the transmitting and receiving sides are separate, such as a structure where a transducer for transmitting the wave and a transducer for receiving the reflected wave are provided separately.

[0038] The control unit 22 includes an input / output device 41, a storage device 42, and a processor 43. The input / output device 41 is an interface device that enables the control unit 22 to transmit and receive information with external devices (transceiver unit 21, ECU 12, etc.). The storage device 42 includes main storage devices such as ROM (Read Only Memory) and RAM (Random Access Memory), and auxiliary storage devices such as HDD (Hard Disk Drive) and SSD (Solid State Drive). The processor 43 is an integrated circuit that performs various processes to implement the functions of the control unit 22. For example, it can be constructed using a CPU (Central Processing Unit), ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), etc., which operate according to a program. The processor 43 performs various arithmetic and control processes by reading and executing programs stored in the storage device 42.

[0039] ECU 12 is a unit that executes various processes for controlling vehicle 1 based on information obtained from object detection device 11, etc. ECU 12 includes an input / output device 51, a storage device 52, and a processor 53. The input / output device 51 is an interface device that enables the ECU 12 to transmit and receive information with external mechanisms (object detection device 11, drive mechanism, braking mechanism, steering mechanism, transmission mechanism, in-vehicle display, speaker, various sensors, etc.). The storage device 52 includes main storage devices such as ROM and RAM, and auxiliary storage devices such as HDD and SSD. The processor 53 is an integrated circuit that executes various processes to implement the functions of ECU 12; for example, it can be constructed using a CPU, ASIC, FPGA, etc. The processor 53 reads the program stored in the storage device 52 and performs various arithmetic and control processes.

[0040] Figure 3 This is a diagram illustrating an example of the distance calculation method based on the TOF method in the first embodiment. Figure 3 The envelope L is shown, representing the change in intensity (signal level) of the ultrasonic waves transmitted and received by the transceiver unit 21 over time. Figure 3 In the graph shown, the horizontal axis corresponds to time (TOF), and the vertical axis corresponds to the intensity of the ultrasonic waves transmitted and received by the transceiver unit 21 (the magnitude of the vibration of the transducer 31).

[0041] The envelope L represents the change in the magnitude and intensity of the oscillation of oscillator 31 over time. From... Figure 3The envelope L shown can be used to read the following: by driving oscillator 31 from time t0 and oscillating for time Ta, the transmission of the transmitted wave is completed at time t1. During the time Tb from there until time t2, the oscillation of oscillator 31 continues while decaying due to inertia. Therefore, in Figure 3 In the graph shown, time Tb corresponds to the so-called reverberation time.

[0042] The envelope L, starting at timing t0 from the start of wave transmission, reaches a peak value t4 after time Tp, where the magnitude of the vibration of oscillator 31 exceeds the threshold Th. This threshold Th is a value set to distinguish whether the vibration of oscillator 31 is caused by the reception of reflected waves from obstacle O or by the reception of reflected waves from objects other than obstacle O (such as road surface G). While the threshold Th is presented as a fixed value here, it can also be a variable value that varies depending on the situation. Vibrations with peak values ​​exceeding the threshold Th can be considered to be caused by the reception of reflected waves from obstacle O.

[0043] In this example, the envelope L represents the vibration attenuation of oscillator 31 after time t4. Therefore, time t4 corresponds to the time when the reception of the reflected wave from obstacle O is completed; in other words, it corresponds to the time when the last transmitted wave sent at time t1 returns as a reflected wave.

[0044] Furthermore, in the envelope L, timing t3, which is the starting point of the peak of timing t4, corresponds to the timing at which the reflected wave from obstacle O begins to be received; in other words, it corresponds to the timing at which the transmitted wave initially sent at timing t0 returns as a reflected wave. Therefore, the time ΔT between timing t3 and timing t4 is equal to the time Ta, which is the transmission time of the transmitted wave.

[0045] As described above, in order to determine the distance from the ultrasonic transceiver 21 to the obstacle O using Time-of-Flight (TOF), it is necessary to calculate the time Tf between the timing t0 when the transmitted wave begins to be transmitted and the timing t3 when the reflected wave begins to be received. This time Tf can be obtained by subtracting the time ΔT, which is equal to the transmission time Ta, from the time Tp, which is the difference between timing t0 and the timing t4 when the reflected wave intensity exceeds the threshold Th and reaches its peak.

[0046] The timing t0 at which the transmitted wave begins can be easily determined as the timing at which the object detection device 200 begins operation, and the transmission time Ta of the transmitted wave can be predetermined by setting parameters. Therefore, by determining the timing t4 at which the intensity of the received reflected wave reaches a peak value above the threshold Th, the distance from the vehicle 1 (the transceiver unit 21, which serves as the ultrasonic wave source and receiver) to the obstacle O can be calculated. Furthermore, the above calculation method is merely an example; the distance from the vehicle 1 to the obstacle O can also be calculated using known or novel methods.

[0047] Figure 4 This diagram illustrates an example of the functional structure of the object detection device 11 according to the first embodiment. The control unit 22 of the object detection device 11 in this embodiment includes an echo information generation unit 101, a threshold calculation unit 102, a determination unit 103, and an output unit 104. These functional units can be configured, for example, by... Figure 2 The object detection device 11 shown is implemented through the cooperation of its hardware and software (programs, etc.). In addition, at least some of these functional parts can also be implemented by dedicated hardware (circuit).

[0048] The echo information generation unit 101 generates echo information representing the temporal variation of the intensity of the reflected wave based on information acquired from the transceiver unit 21. The echo information may include, for example... Figure 3 The data for the envelope L shown.

[0049] The threshold calculation unit 102 calculates a CFAR threshold that varies as the vehicle 1 moves (an example of a varying threshold) by performing CFAR processing on the echo information. The threshold calculation unit 102 calculates a moving average of the intensity of the reflected wave based on the echo information and calculates the CFAR threshold based on this moving average.

[0050] The determination unit 103 determines whether there is an obstacle around the vehicle 1 based on the echo information, a preset fixed threshold, and a CFAR threshold calculated by the threshold calculation unit 102. In this embodiment, the determination unit 103 determines that an obstacle exists when the intensity of the reflected wave is greater than the fixed threshold and the CFAR threshold. When the determination unit 103 determines that an obstacle exists, it generates obstacle information related to the obstacle. The obstacle information may include, for example, the distance from the vehicle 1 (transceiver unit 21) to the obstacle and the relative speed of the obstacle.

[0051] The output unit 104 outputs the obstacle information generated by the determination unit 103 to a pre-set mechanism (such as ECU 12).

[0052] Figure 5This diagram illustrates an example of the CFAR processing according to the first embodiment. In the CFAR processing shown here, firstly, received signals representing the intensity of reflected waves are sampled from the echo information at predetermined time intervals. Then, the sum of the intensity values ​​of the N samples of reflected waves received during a first period Δt1 before a certain detection time t, i.e., the first sum Σ1, is calculated. Additionally, the sum of the intensity values ​​of the N samples of reflected waves received during a second period Δt2 after the detection time t, i.e., the second sum Σ2, is calculated. Then, the sum Σ of the first sum Σ1 and the second sum Σ2 is divided by the sum of the number of samples N during the first period Δt1 and the number of samples N during the second period Δt2, i.e., 2N, to calculate the moving average A. Then, a CFAR threshold Thc is calculated by performing pre-set accumulation processing, addition processing, etc., on the moving average A. Accumulation processing is the process of accumulating a pre-set constant on the moving average A. Addition processing is the process of adding a pre-set constant to the moving average A. Then, using the difference signal representing the difference between the intensity value corresponding to the detection time t and the CFAR threshold Thrc, it is determined whether there is an obstacle at the distance corresponding to the detection time t.

[0053] Furthermore, the calculation method for the CFAR threshold Thc is not limited to the above. For example, in the above description, the average of all values ​​corresponding to the periods Δt1 and Δt2 before and after the detection time t was used as the moving average A using the CA (Cell Averaging) CFAR processing method, but the CFAR threshold Thc can also be calculated using the GO (Greatest Of) CFAR processing method, the SO (Smallest Of) CFAR processing method, etc. The GO-CFAR processing method refers to the processing that uses the larger of the first and Σ1 and the second and Σ2 to calculate the moving average A. The SO-CFAR processing method refers to the processing that uses the smaller of the first and Σ1 and the second and Σ2 to calculate the moving average A.

[0054] Figure 6 This is a diagram illustrating an example of the fixed threshold Thrf involved in the first embodiment. Figure 6 The diagram shows the envelope L and fixed threshold Thf in the presence of an obstacle. The peak P1 in the envelope L is caused by the reflected wave from an obstacle located at a distance D1 from the vehicle 1 (transceiver unit 21).

[0055] The fixed threshold Thf is a fixed value uniquely determined relative to the distance from vehicle 1. The fixed threshold Thf can also be pre-stored in a suitable storage device (e.g., storage device 42) mounted on vehicle 1. The specific method for setting the fixed threshold Thf should be appropriately determined based on the specifications of vehicle 1, the performance of transceiver 21, etc., but the fixed threshold Thf can also be set, for example, based on the intensity of the reflected wave from the obstacle according to a statistical value (e.g., a lower limit value) for each distance. Since the intensity of the reflected wave from the obstacle decreases with increasing distance from vehicle 1, the fixed threshold Thf is usually set to decrease with increasing distance from vehicle 1. Furthermore, a fixed threshold Thf that decreases linearly with increasing distance is shown here, but the form of the fixed threshold Thf is not limited to this.

[0056] Figure 7 This is a diagram illustrating an example of the CFAR threshold Thc in the presence of obstacles in the first embodiment. Figure 7 The diagram shows the envelope L, the moving average A of the envelope L, and the CFAR threshold Thc in the presence of obstacles.

[0057] The CFAR threshold Thc shown here is the value obtained by accumulating the moving average A of the envelope L (the intensity of the reflected wave). The moving average A and the CFAR threshold Thc vary with road surface undulations, etc., as vehicle 1 travels. The intensity (peak P1) of the reflected wave from the obstacle is typically greater than the CFAR threshold Thc.

[0058] By using the CFAR threshold Thc as described above, the effects of noise caused by road surface undulations can be basically suppressed, but depending on the situation, it may be susceptible to noise.

[0059] Figure 8 This is a diagram illustrating an example of the CFAR threshold Thc in the first embodiment when no obstacles are present. Figure 8 The diagram shows the envelope L, the moving average A of the envelope L, and the CFAR threshold Thc in the absence of obstacles. The peak P2 in the envelope L is caused by reflected waves from a non-obstacle (e.g., a small step on the road surface) located at a distance D2 from the vehicle 1. The CFAR threshold Thc shown here is related to... Figure 7 Similarly, it is the value of the moving average A of the envelope L after cumulative processing.

[0060] When the road surface remains smooth for a certain period, the CFAR threshold Thrc is low. Furthermore, if small non-obstacles such as steps appear on this road surface, then... Figure 8As shown, the intensity (peak P2) of the reflected wave from the non-obstacle is sometimes greater than the set low CFAR threshold Thrc.

[0061] As mentioned above, if only the CFAR threshold Thc is used to determine the presence or absence of obstacles, false detections of obstacles may occur because the road surface condition is easily affected by noise. Therefore, in this embodiment, both the fixed threshold Thf and the CFAR threshold Thc are used to determine the presence or absence of obstacles.

[0062] Figure 9 This is a diagram illustrating an example of the relationship between the envelope L, the fixed threshold Thf, and the CFAR threshold Thc in the presence of obstacles in the first embodiment. Figure 9 The diagram shows the state where the peak value P1 of the intensity of the reflected wave from the obstacle exceeds both the fixed threshold Thf and the CFAR threshold Thc.

[0063] In this embodiment, such as Figure 9 As shown, if the intensity of the reflected wave is greater than the fixed threshold Thf and the CFAR threshold Thc, an obstacle is determined to exist.

[0064] Figure 10 This is a diagram illustrating an example of the relationship between the envelope L, the fixed threshold Thf, and the CFAR threshold Thc in the first embodiment when there are no obstacles. Figure 10 The diagram shows the state where the peak value P2 of the intensity of the reflected wave from the non-obstacle is greater than the CFAR threshold Thc but less than the fixed threshold Thf.

[0065] In this embodiment, such as Figure 10 As shown, if the intensity of the reflected wave is less than at least one of the fixed threshold Thf or the CFAR threshold Thc, it is not determined that an obstacle exists.

[0066] Figure 11 This is a flowchart illustrating an example of the processing in the object detection device 11 of the first embodiment. In step S101, when the transceiver unit 21 starts transmitting and receiving ultrasonic waves, in step S102, the echo information generation unit 101 generates echo information representing the temporal variation of the intensity of reflected waves from objects present around the vehicle 1. In step S103, the threshold calculation unit 102 calculates the CFAR threshold Thrc based on the echo information.

[0067] In step S104, the determination unit 103 determines whether the intensity I of the reflected wave obtained from the echo information is greater than a fixed threshold Thf (I>Thf) and whether the intensity I is greater than the CFAR threshold Thc (I>Thc).

[0068] In step S104, if I is not greater than Thf and I is not greater than Thc (S104: No), that is, if the intensity I of the reflected wave is less than at least one of the fixed threshold Thf or the CFAR threshold Thc, it is determined that there is no obstacle and the routine ends.

[0069] In step S104, if I>Thf and I>Thc (S104: Yes), in step S105, the determination unit 103 determines that an obstacle exists and generates obstacle information related to the obstacle. In step S106, the output unit 104 outputs the obstacle information to the ECU 12 and other mechanisms.

[0070] As described above, according to this embodiment, an obstacle is determined to exist when the intensity of the reflected wave is greater than both a fixed threshold and a CFAR threshold. This reduces the likelihood of false obstacle detection when the CFAR threshold is set too low.

[0071] Hereinafter, other embodiments will be described with reference to the accompanying drawings, but descriptions of contents that are the same as or identical to those of the first embodiment will be omitted as appropriate.

[0072] (Second Implementation)

[0073] The object detection device 11 of the second embodiment determines the presence of an obstacle if the intensity of the reflected wave is greater than a fixed threshold within a pre-set short-range range, and determines the presence of an obstacle if the intensity of the reflected wave is greater than both the fixed threshold and the CFAR threshold within a range farther than the short-range range.

[0074] Figure 12 This is a diagram illustrating an example of the relationship between the envelope L, the fixed threshold Thf, and the CFAR threshold Thc in the presence of obstacles in the second embodiment. Figure 13 This is a diagram illustrating an example of the relationship between the envelope L, the fixed threshold Thf, and the CFAR threshold Thc in the second embodiment when there are no obstacles. Figure 12 and 13 The diagram shows the short-range range Rn. The short-range range Rn should be appropriately set according to the specifications of vehicle 1, the performance of transceiver unit 21, etc., for example, it can be the range within 1m of vehicle 1 (transceiver unit 21).

[0075] In this embodiment, within the short-range Rn, the CFAR threshold Thc is not considered; the presence or absence of an obstacle is determined based on whether the intensity of the reflected wave is greater than a fixed threshold Thf. Figure 12 In the example shown, since the peak value P1 that appears within the close range Rn exceeds the fixed threshold Thf, it is determined that an obstacle exists.

[0076] Furthermore, in this embodiment, in areas farther than the near distance range Rn, the presence or absence of obstacles is determined based on both a fixed threshold Thf and a CFAR threshold Thc, similar to the first embodiment. Figure 13 In the example shown, the peak P2 that appears in a region farther than the near distance range Rn exceeds the CFAR threshold Thc, but since it does not exceed the fixed threshold Thf, it is determined that there is no obstacle.

[0077] Figure 14 This is a flowchart illustrating an example of the processing in the object detection device 11 according to the second embodiment. In step S201, when the transceiver unit 21 starts transmitting and receiving ultrasonic waves, in step S202, the echo information generation unit 101 generates echo information representing the temporal variation of the intensity of reflected waves from objects present around the vehicle 1. In step S203, the threshold calculation unit 102 calculates the CFAR threshold Thrc based on the echo information.

[0078] In step S204, the determination unit 103 determines whether the intensity I of the reflected wave obtained from the echo information is greater than a fixed threshold Thf (I>Thf). In step S204, if I is not greater than Thf (S204: No), it is determined that there is no obstacle, and the routine ends.

[0079] In step S204, if I > Thf (S204: Yes), in step S205, the determination unit 103 determines whether the distance corresponding to the peak value where I > Thf is determined to be within the near-range range Rn. In step S205, if the distance is not within the near-range range Rn (S205: No), in step S206, the determination unit 103 determines whether the intensity I of the reflected wave is greater than the CFAR threshold Thc (I > Thc). In step S206, if I > Thc is not (S206: No), it is determined that there is no obstacle, and this routine ends.

[0080] In step S205, if it is determined that the distance is within the short-range range Rn (S205: Yes), or if it is determined in step S206 that I>Thc (S206: Yes), in step S207, the determination unit 103 determines that an obstacle exists and generates obstacle information related to the obstacle. In step S208, the output unit 104 outputs the obstacle information to the ECU 12 and other mechanisms.

[0081] As described above, according to this embodiment, within a pre-set short-range area, an obstacle is determined to exist if the intensity of the reflected wave is greater than a fixed threshold. In areas farther than the short-range area, an obstacle is determined to exist if the intensity of the reflected wave is greater than both the fixed threshold and the CFAR threshold. This is because within the short-range area, the fixed threshold can be set with high precision, reducing the need to use the CFAR threshold. Thus, by limiting the range in which the CFAR threshold is used, the processing load when calculating the CFAR threshold, etc., can be reduced.

[0082] (Third Implementation)

[0083] Figure 15 This is a diagram illustrating an example of the functional structure of the object detection device 11 according to the third embodiment. For example... Figure 15 As shown, in addition to the echo information generation unit 101, threshold calculation unit 102, determination unit 103 and output unit 104 described above, the control unit 22 of the object detection device 11 in this embodiment also includes a reliability determination unit 201.

[0084] The reliability determination unit 201 determines the reliability of the determination result (obstacle information) of the determination unit 103 based on the difference between the intensity of the reflected wave corresponding to the obstacle and the fixed threshold Thf, and generates reliability information representing the reliability.

[0085] In this embodiment, the output unit 104 outputs the obstacle information generated by the determination unit 103 and the reliability information generated by the reliability determination unit 201 to the ECU 12 and other mechanisms in association.

[0086] Figure 16 This is a diagram illustrating an example of the relationship between the envelope L, the fixed threshold Thf, and the CFAR threshold Thc in the presence of obstacles in the third embodiment. Figure 16 The figure shows the difference ΔI between the intensity of the reflected wave of the peak P1 corresponding to the obstacle and the fixed threshold Thf.

[0087] In this embodiment, the reliability determination unit 201 determines the reliability of obstacle information related to the obstacle corresponding to the peak value P1 based on the difference ΔI between the intensity of the peak value P1, which satisfies the condition for determining it to be an obstacle (here, the intensity of the reflected wave is greater than the fixed threshold Thf and the CFAR threshold Thc), and the fixed threshold Thf. This reliability is determined, for example, by the fact that the larger the difference ΔI, the higher the reliability.

[0088] Figure 17This is a flowchart illustrating an example of the processing in the object detection device 11 according to the third embodiment. In step S301, when the transceiver unit 21 starts transmitting and receiving ultrasonic waves, in step S302, the echo information generation unit 101 generates echo information representing the temporal variation of the intensity of reflected waves from objects present around the vehicle 1. In step S303, the threshold calculation unit 102 calculates the CFAR threshold Thrc based on the echo information.

[0089] In step S304, the determination unit 103 determines whether the intensity I of the reflected wave obtained from the echo information is greater than a fixed threshold Thf (I>Thf) and whether the intensity I is greater than the CFAR threshold Thc (I>Thc).

[0090] In step S304, if I > Thf and I > Thc (S304: No), that is, when the intensity I of the reflected wave is less than at least one of the fixed threshold Thf or the CFAR threshold Thc, it is determined that there is no obstacle and the routine ends.

[0091] In step S304, if I > Thf and I > Thc (S304: Yes), in step S305, the determination unit 103 determines that an obstacle exists and generates obstacle information related to the obstacle. In step S306, reliability information representing the reliability of the obstacle information (the obstacle information generated in step S305) is generated based on the difference ΔI between the intensity I (the intensity of the reflected wave that satisfies the condition of step S304) and the fixed threshold Thf. In step S306, the output unit 104 outputs the obstacle information and the reliability information to a mechanism such as the ECU 12.

[0092] As described above, according to this embodiment, reliability information representing the reliability of obstacle information is generated based on the difference between the intensity of the reflected wave and a fixed threshold. By utilizing such reliability information, vehicle 1 control based on obstacle information can be performed with higher precision.

[0093] (Modified example)

[0094] In the above embodiment, a structure is shown that uses ultrasonic waves as the transmitted and received waves for detecting obstacles, but the structure of the object detection device is not limited to this. For example, it can also be a structure that uses millimeter-wave radar, LiDAR (Light Detection and Ranging) sensors, etc.

[0095] Furthermore, in the above embodiment, the reflected wave is assumed to be a direct wave transmitted and received by the same transceiver unit 21. However, the reflected wave may also be an indirect wave, where a transmitted wave sent from one transceiver unit 21 (e.g., transceiver unit 21E) is received by another transceiver unit 21 (e.g., transceiver unit 21F). In this case, at least one of the fixed threshold or the CFAR threshold can vary depending on whether the reflected wave is a direct wave or an indirect wave.

[0096] The program that enables a computer (e.g., processor 43, etc.) to execute the processing for implementing the functions of the aforementioned object detection device can be provided as an installable or executable file on a computer-readable recording medium such as a Compact Disc-ROM, floppy disk, CD-R, or Digital Versatile Disc (DVD). Alternatively, the program can also be provided or distributed via a network such as the Internet.

[0097] The embodiments of the present invention have been described above, but the above embodiments and their modifications are merely examples and are not intended to limit the scope of the invention. The above-described new embodiments and modifications can be implemented in various ways, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. The above-described embodiments and modifications are included within the scope or spirit of the invention, and are included within the scope of the invention as described in the claims and its equivalents.

[0098] Explanation of reference numerals in the attached figures

[0099] 1…vehicle (moving body), 11…object detection device, 21, 21A~21L…transceiver unit, 102…threshold calculation unit, 103…determination unit, 201…reliability determination unit, O…obstacle, Thc…CFAR threshold (variable threshold), Thf…fixed threshold.

Claims

1. An object detection device that detects obstacles existing around a moving body based on a temporal change in the intensity of a reflected wave generated by the reflection of a transmitted wave from a moving body by the object, wherein, The object detection device includes: The threshold calculation unit calculates a variation threshold that changes with the movement of the moving body based on the moving average of the intensity of the reflected wave; and The determination unit determines that an obstacle exists if the intensity of the reflected wave is greater than a preset fixed threshold and the variable threshold.

2. The object detection device according to claim 1, wherein, The determination unit determines the presence of the obstacle if the intensity of the reflected wave is greater than the fixed threshold within a pre-set short-range area, and determines the presence of the obstacle if the intensity of the reflected wave is greater than both the fixed threshold and the variable threshold within a range farther than the short-range area.

3. The object detection device according to claim 1 or 2, wherein, The object detection device further includes a reliability determination unit that determines the reliability of the determination result of the determination unit based on the difference between the intensity of the reflected wave and the fixed threshold.

4. The object detection device according to claim 1 or 2, wherein, The fixed threshold decreases as the distance from the moving body to the object increases in a linear fashion.

5. The object detection device according to claim 3, wherein, The fixed threshold decreases as the distance from the moving body to the object increases in a linear fashion.

6. The object detection device according to claim 3, wherein, The reliability is determined to be higher if the difference is larger.

7. The object detection device according to claim 5, wherein, The reliability is determined to be higher if the difference is larger.

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