Object detection device

Abstract

To provide an object detection device capable of suppressing erroneous detection of an obstacle.SOLUTION: An object detection device detects an obstacle present in the vicinity of a moving body based on time-series changes in the intensity of a reflected wave generated when a transmission wave transmitted from the moving body is reflected by an object. The object detection device includes a threshold calculation unit that calculates a variable threshold that varies in accordance with the movement of the moving body based on a moving average value of the intensity of the reflected wave, 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 and the variable threshold.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] In moving bodies such as vehicles, object detection devices are used to detect obstacles present around the moving bodies based on information such as TOF (Time Of Flight) and Doppler shift obtained by transmitting and receiving ultrasonic waves, etc. In such object detection devices, CFAR (Constant False Alarm Rate) processing is used as a technique for suppressing the influence of noise caused by reflected waves from objects that are not the detection target (e.g., road surfaces, etc.). According to CFAR processing, a threshold value for determining whether an object that reflects a reflected wave is an obstacle or not is optimized according to the condition of the road surface, etc., based on a moving average value of the intensity of the reflected wave that changes over time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-206011 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to the above-mentioned CFAR processing, the influence of noise can basically be suppressed, but depending on the situation, it may be susceptible to the influence of noise. For example, if the road surface on which the moving object is traveling is smooth, the threshold value is set low, so if a non-obstacle such as a small step suddenly appears on the road surface in such a state, the strength of the reflected wave from the non-obstacle is likely to exceed the threshold value. In such a case, it is highly likely that an obstacle is erroneously determined to exist even when there is no obstacle.

[0005] The present invention has been made in view of the above, and provides an object detection device capable of suppressing erroneous detection of an obstacle. [Means for solving the problem]

[0006] One aspect of the present invention is an object detection device that detects obstacles present in the vicinity of a moving body based on time-series changes in the intensity of a reflected wave generated when a transmission wave transmitted from the moving body is reflected by an object, and includes a threshold calculation unit that calculates a variable threshold that varies in accordance with the movement of the moving body based on a moving average value of the intensity of the reflected wave, and a determination unit that determines that an obstacle is present when the intensity of the reflected wave is greater than predetermined fixed threshold and variable threshold. Effect of the Invention

[0007] According to the present invention, it is possible to provide an object detection device capable of suppressing erroneous detection of an obstacle. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a vehicle according to the first embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of the configuration of the vehicle control system according to the first embodiment. [Diagram 3] FIG. 3 is a diagram showing an example of a distance calculation method using the TOF method according to the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of a functional configuration of the object detection device according to the first embodiment. [Diagram 5] FIG. 5 is a diagram illustrating an example of the CFAR processing according to the first embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of the fixed threshold value according to the first embodiment. [Figure 7] FIG. 7 is a diagram showing an example of the CFAR threshold value when an obstacle exists in the first embodiment. [Figure 8] FIG. 8 is a diagram showing an example of the CFAR threshold value when no obstacle exists in the first embodiment. [Figure 9] FIG. 9 is a diagram illustrating an example of the relationship between the envelope curve, the fixed threshold value, and the CFAR threshold value when an obstacle exists in the first embodiment. [Figure 10] FIG. 10 is a diagram showing an example of the relationship between the envelope curve, the fixed threshold value, and the CFAR threshold value in the case where no obstacle is present in the first embodiment. [Figure 11] FIG. 11 is a flowchart showing an example of processing in the object detection device according to the first embodiment. [Figure 12] FIG. 12 is a diagram showing an example of the relationship between the envelope curve, the fixed threshold value, and the CFAR threshold value in the case where an obstacle exists in the second embodiment. [Figure 13] FIG. 13 is a diagram showing an example of the relationship between the envelope curve, the fixed threshold value, and the CFAR threshold value in the case where no obstacle is present in the second embodiment. [Figure 14] FIG. 14 is a flowchart showing an example of processing in the object detection device according to the second embodiment. [Figure 15] FIG. 15 is a diagram illustrating an example of the functional configuration of an object detection device according to the third embodiment. [Figure 16] FIG. 16 is a diagram showing an example of the relationship between the envelope curve, the fixed threshold value, and the CFAR threshold value in the case where an obstacle exists in the third embodiment. [Figure 17] FIG. 17 is a flowchart showing an example of processing in the object detection device according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The configuration of the embodiment described below and the actions and effects brought about by the configuration are merely examples, and the present invention is not limited to the following description.

[0010] (First embodiment) 1 is a diagram showing an example of the configuration of a vehicle 1 according to the first embodiment. The vehicle 1 is an example of a moving body on which an object detection device according to the present embodiment is mounted. The object detection device according to the present embodiment is a device that detects obstacles present around the vehicle 1 based on information such as TOF (Time Of Flight) and Doppler shift acquired by transmitting and receiving ultrasonic waves.

[0011] The object detection device according to this embodiment includes a plurality of transceivers 21A-21L. Hereinafter, when there is no need to distinguish between the plurality of transceivers 21A-21L, they may be referred to as transceivers 21. Each transceiver 21 is installed on a vehicle body 2 serving as the exterior of a vehicle 1, transmits ultrasonic waves toward the outside of the vehicle body 2, and receives ultrasonic waves generated when the ultrasonic waves are reflected by an object present outside the vehicle body 2. Hereinafter, ultrasonic waves transmitted from the transceiver 21 may be referred to as a transmission wave, and ultrasonic waves generated when the transmission wave is reflected by an object may be referred to as a reflected wave.

[0012] 1, four transceivers 21A-21D are arranged at the front end of the vehicle body 2, four transceivers 21E-21H are arranged at the rear end, two transceivers 21I, 21J are arranged on the right side, and two transceivers 21K, 21L are arranged on the left side. Note that the number and installation positions of the transceivers 21 are not limited to this example.

[0013] 2 is a diagram showing an example of the configuration 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 an object detection device 11. The vehicle control system 10 according to this embodiment includes the object detection device 11 and an ECU 12.

[0014] The object detection device 11 includes a plurality of transmitting / receiving units 21 and a control unit 22. Each transmitting / receiving unit 21 includes a transducer 31 configured using a piezoelectric element or the like, an amplifier, etc., and realizes transmission and reception of ultrasonic waves by the vibration of the transducer 31. Specifically, each transmitting / receiving unit 21 transmits ultrasonic waves generated in response to the vibration of the transducer 31 as a transmission wave, and detects the vibration of the transducer 31 caused by the reflected wave of the transmission wave reflected by an object such as an obstacle O or a road surface G. The obstacle O is an object to be detected among objects present around the vehicle 1, and may be, for example, another vehicle, a road accessory, a wall, a person, a curb, a car stop, etc. The vibration of the transducer 31 is converted into an electric signal, and based on the electric signal, a TOF corresponding to the distance from the transmitting / receiving unit 21 to the obstacle O, a Doppler shift corresponding to the relative speed between the vehicle 1 and the obstacle O, etc. can be obtained.

[0015] 2, a configuration is illustrated in which both transmission of the transmission wave and reception of the reflected wave are performed using a single transducer 31, but the configuration of the transceiver unit 21 is not limited to this. For example, the transmission side and the reception side may be separated, such as a configuration in which a transducer for transmitting the transmission wave and a transducer for receiving the reflected wave are separately provided.

[0016] 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 transmission and reception of information between the control unit 22 and external devices (the transmission / reception unit 21, the ECU 12, etc.). The storage device 42 includes a main storage device such as a read only memory (ROM) and a random access memory (RAM), and an auxiliary storage device such as a hard disk drive (HDD) and a solid state drive (SSD). The processor 43 is an integrated circuit that executes various processes for realizing the functions of the control unit 22, and may be configured using, for example, a central processing unit (CPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc. that operate according to a program. The processor 43 executes various arithmetic processes and control processes by reading and executing the programs stored in the storage device 42.

[0017] The ECU 12 is a unit that executes various processes for controlling the vehicle 1 based on information acquired from the object detection device 11 and the like. The ECU 12 has an input / output device 51, a storage device 52, and a processor 53. The input / output device 51 is an interface device that enables transmission and reception of information between the ECU 12 and external mechanisms (such as the object detection device 11, the drive mechanism, the braking mechanism, the steering mechanism, the transmission mechanism, the in-vehicle display, the speaker, and various sensors). The storage device 52 includes a main storage device such as a ROM or RAM, and an auxiliary storage device such as an HDD or SSD. The processor 53 is an integrated circuit that executes various processes for realizing the functions of the ECU 12, and may be configured using, for example, a CPU, an ASIC, an FPGA, or the like. The processor 53 reads out a program stored in the storage device 52 and executes various arithmetic processes and control processes.

[0018] Fig. 3 is a diagram showing an example of a method for calculating distance using the TOF method according to the first embodiment. Fig. 3 illustrates an envelope curve L indicating a change over time in the intensity (signal level) of ultrasonic waves transmitted and received by the transmitting and receiving unit 21. In the graph shown in Fig. 3, the horizontal axis corresponds to time (TOF), and the vertical axis corresponds to the intensity of ultrasonic waves transmitted and received by the transmitting and receiving unit 21 (the magnitude of vibration of the transducer 31).

[0019] The envelope curve L indicates the change over time in the strength indicating the magnitude of the vibration of the oscillator 31. From the envelope curve L illustrated in Fig. 3, it can be seen that the oscillator 31 is driven to vibrate for a period of time Ta from timing t0, and the transmission of the transmission wave is completed at timing t1, and then the vibration of the oscillator 31 due to inertia continues while attenuating for a period of time Tb until timing t2. Therefore, in the graph shown in Fig. 3, the period of time Tb corresponds to the so-called reverberation time.

[0020] The envelope L reaches a peak at a time t4, which is a time Tp after the time t0 when the transmission of the transmission wave starts, at which the magnitude of the vibration of the vibrator 31 reaches or exceeds a threshold value Th. This threshold value Th is a value that is set to distinguish whether the vibration of the vibrator 31 is caused by the reception of a reflected wave from the obstacle O or the reception of a reflected wave from an object other than the obstacle O (e.g., the road surface G, etc.). Note that although the threshold value Th is shown here as a constant value, the threshold value Th may be a variable value that changes depending on the situation. Vibrations having a peak equal to or greater than the threshold value Th can be considered to be caused by the reception of a reflected wave from the obstacle O.

[0021] In this example, the envelope curve L indicates that the vibration of the transducer 31 is attenuated after the timing t4. Therefore, the timing t4 corresponds to the timing at which the reception of the reflected wave from the obstacle O is completed, in other words, the timing at which the transmission wave finally transmitted at the timing t1 returns as a reflected wave.

[0022] Furthermore, in the envelope L, timing t3 as the start point of the peak at timing t4 corresponds to the timing at which reception of the reflected wave from the obstacle O begins, in other words, the timing at which the transmission wave first transmitted at timing t0 returns as a reflected wave. Therefore, the time ΔT between timing t3 and timing t4 is equal to the time Ta as the transmission time of the transmission wave.

[0023] From the above, in order to use TOF to find the distance from the transmitting / receiving unit 21, which is the source of transmitting and receiving ultrasonic waves, to the obstacle O, it is necessary to find the time Tf between the timing t0 when the transmission of the transmitted wave begins and the timing t3 when the reflected wave begins to be received. This time Tf can be found by subtracting the time ΔT, which is equal to the time Ta as the transmission time of the transmitted wave, from the time Tp, which is the difference between the timing t0 and the timing t4 when the intensity of the reflected wave reaches a peak by exceeding the threshold value Th.

[0024] The timing t0 when the transmission wave starts to be transmitted can be easily identified as the timing when the object detection device 200 starts to operate, and the time Ta as the transmission time of the transmission wave is determined in advance by settings, etc. Therefore, by identifying the timing t4 when the intensity of the reflected wave reaches a peak and exceeds the threshold value Th, the distance from the vehicle 1 (the transceiver unit 21 which is the source of transmission and reception of the ultrasonic waves) to the obstacle O can be obtained. Note that the above calculation method is merely an example, and the distance from the vehicle 1 to the obstacle O may be calculated by appropriately using a known or new method.

[0025] Fig. 4 is a diagram showing an example of the functional configuration of the object detection device 11 according to the first embodiment. The control unit 22 of the object detection device 11 according to 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 realized, for example, by cooperation between the hardware and software (programs, etc.) of the object detection device 11 as shown in Fig. 2. Furthermore, at least a part of these functional units may be realized by dedicated hardware (circuits).

[0026] The echo information generating unit 101 generates echo information indicating a time-series change in the intensity of the reflected wave based on information acquired from the transmitting / receiving unit 21. The echo information may include, for example, data of an envelope L as illustrated in FIG.

[0027] The threshold calculation unit 102 performs CFAR processing on the echo information to calculate a CFAR threshold (an example of a variable threshold) that varies in accordance with the movement of the vehicle 1. The threshold calculation unit 102 calculates a moving average value of the intensity of the reflected wave based on the echo information, and calculates a CFAR threshold value based on the moving average value.

[0028] The determination unit 103 determines whether or not an obstacle exists around the vehicle 1 based on the echo information, a predetermined 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 (transmission / reception unit 21) to the obstacle, the relative speed of the obstacle, and the like.

[0029] The output unit 104 outputs the obstacle information generated by the determination unit 103 to a predetermined mechanism (eg, the ECU 12, etc.).

[0030] FIG. 5 is a diagram showing an example of CFAR processing according to the first embodiment. In the CFAR processing illustrated here, first, a received signal indicating the intensity of a reflected wave from echo information is sampled at a predetermined time interval. Then, a first sum Σ1 is calculated, which is the sum of the intensity values ​​of the reflected wave received in a first period Δt1 before a certain detection timing t for the number of samples N. Also, a second sum Σ2 is calculated, which is the sum of the intensity values ​​of the reflected wave received in a second period Δt2 after the detection timing t for the number of samples N. Then, a moving average value A is calculated by dividing the sum Σ obtained by adding up the first sum Σ1 and the second sum Σ2 by 2N, which is the sum of the number of samples N in the first period Δt1 and the number of samples N in the second period Δt2. Then, a CFAR threshold value Thc is calculated by performing a predetermined integration process, addition process, or the like on the moving average value A. The integration process is a process of integrating a predetermined constant with respect to the moving average value A. The addition process is a process of adding a predetermined constant with respect to the moving average value A. Then, a difference signal indicating the difference between the intensity value corresponding to the detection time t and the CFAR threshold value Thc is used to determine whether or not an obstacle is present at the distance corresponding to the detection time t.

[0031] The calculation method of the CFAR threshold Thc is not limited to the above. For example, in the above description, the CA (Cell Averaging)-CFAR process is described in which the average value of all values ​​corresponding to the periods Δt1 and Δt2 before and after the detection timing t is set as the moving average value A, but the CFAR threshold Thc may be calculated by GO (Greatest Of)-CFAR process, SO (Smallest Of)-CFAR process, or the like. The GO-CFAR process is a process in which the moving average value A is calculated using the larger value of the first sum Σ1 and the second sum Σ2. The SO-CFAR process is a process in which the moving average value A is calculated using the smaller value of the first sum Σ1 and the second sum Σ2.

[0032] Fig. 6 is a diagram showing an example of the fixed threshold value Thf according to the first embodiment. Fig. 6 illustrates an envelope curve L and the fixed threshold value Thf when an obstacle is present. A peak P1 in the envelope curve L is due to a reflected wave from an obstacle present at a position at a distance D1 from the vehicle 1 (transmitter / receiver 21).

[0033] The fixed threshold Thf is a fixed value that is uniquely determined for the distance from the vehicle 1. The fixed threshold Thf may be stored in advance in an appropriate storage device (such as the storage device 42) mounted on the vehicle 1. A specific method for setting the fixed threshold Thf should be appropriately determined according to the specifications of the vehicle 1 and the performance of the transceiver unit 21, and the like, but the fixed threshold Thf may be set, for example, based on a statistical value (such as a lower limit value) of the strength of the reflected wave from an obstacle for each distance. Since the strength of the reflected wave from an obstacle decreases as the distance from the vehicle 1 increases, the fixed threshold Thf is usually set to decrease as the distance from the vehicle 1 increases. Note that, although a fixed threshold Thf that decreases linearly with increasing distance is exemplified here, the form of the fixed threshold Thf is not limited to this.

[0034] Fig. 7 is a diagram showing an example of the CFAR threshold value Thc when an obstacle exists in the first embodiment. Fig. 7 illustrates an envelope curve L, a moving average value A of the envelope curve L, and a CFAR threshold value Thc when an obstacle exists.

[0035] The CFAR threshold value Thc illustrated here is a value obtained by performing an integration process on the moving average value A of the envelope L (strength of the reflected wave). The moving average value A and the CFAR threshold value Thc vary according to the undulations of the road surface while the vehicle 1 is traveling. The strength (peak P1) of the reflected wave from an obstacle is usually greater than the CFAR threshold value Thc.

[0036] By using the CFAR threshold value Thc as described above, the influence of noise due to unevenness of the road surface and the like can basically be suppressed, but depending on the situation, the vehicle may become more susceptible to the influence of noise.

[0037] Fig. 8 is a diagram showing an example of the CFAR threshold value Thc when no obstacle is present in the first embodiment. Fig. 8 illustrates an envelope L, a moving average value A of the envelope L, and a CFAR threshold value Thc when no obstacle is present. A peak P2 in the envelope L is due to a reflected wave from a non-obstacle (such as a small step on the road surface) that is present at a distance D2 from the vehicle 1. The CFAR threshold value Thc illustrated here is a value obtained by performing an integration process on the moving average value A of the envelope L, similar to Fig. 7.

[0038] The CFAR threshold value Thc is low when the road surface remains smooth for a certain period of time. When a non-obstacle such as a small step appears on the road surface in such a state, the intensity of the reflected wave from the non-obstacle (peak P2) may become larger than the low-set CFAR threshold value Thc, as shown in FIG.

[0039] As described above, if the presence or absence of an obstacle is determined using only the CFAR threshold Thc, it may be susceptible to noise depending on the road surface condition, etc., and there is a possibility that an erroneous detection of an obstacle may occur. Therefore, in this embodiment, the presence or absence of an obstacle is determined using both the fixed threshold Thf and the CFAR threshold Thc.

[0040] Fig. 9 is a diagram showing an example of the relationship between the envelope L, the fixed threshold Thf, and the CFAR threshold Thc when an obstacle is present in the first embodiment. Fig. 9 illustrates a state in which a peak P1 corresponding to the intensity of a reflected wave from an obstacle exceeds both the fixed threshold Thf and the CFAR threshold Thc.

[0041] In this embodiment, as illustrated in FIG. 9, when the intensity of the reflected wave is greater than the fixed threshold Thf and the CFAR threshold Thc, it is determined that an obstacle is present.

[0042] Fig. 10 is a diagram showing an example of the relationship between the envelope L, the fixed threshold Thf, and the CFAR threshold Thc when no obstacle is present in the first embodiment. Fig. 10 illustrates a state in which a peak P2 corresponding to the intensity of a reflected wave from a non-obstacle is greater than the CFAR threshold Thc but smaller than the fixed threshold Thf.

[0043] In this embodiment, as illustrated in FIG. 10, when the intensity of the reflected wave is smaller than at least one of the fixed threshold Thf and the CFAR threshold Thc, it is not determined that an obstacle is present.

[0044] 11 is a flowchart showing an example of processing in the object detection device 11 according to the first embodiment. In step S101, the transmitter / receiver 21 starts transmitting and receiving ultrasonic waves, and in step S102, the echo information generator 101 generates echo information indicating a time-series change in intensity of a reflected wave from an object present around the vehicle 1. In step S103, the threshold calculator 102 calculates a CFAR threshold Thc based on the echo information.

[0045] In step S104, the determination unit 103 determines whether the intensity I of the reflected wave acquired from the echo information is greater than a fixed threshold Thf (I>Thf) and whether the intensity I is greater than a CFAR threshold Thc (I>Thc).

[0046] In step S104, if I>Thf and I>Thc are not satisfied (S104: No), that is, if the intensity I of the reflected wave is smaller than at least one of the fixed threshold Thf and the CFAR threshold Thc, it is determined that no obstacle is present, and this routine ends.

[0047] 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 a mechanism such as the ECU 12.

[0048] As described above, according to the present embodiment, when the strength of the reflected wave is greater than both the fixed threshold and the CFAR threshold, it is determined that an obstacle is present. This makes it possible to reduce the possibility of erroneous detection of an obstacle when the CFAR threshold is set low.

[0049] Other embodiments will be described below with reference to the drawings, but descriptions of parts that are the same as or similar to the first embodiment will be omitted as appropriate.

[0050] Second embodiment The object detection device 11 according to the second embodiment determines that an obstacle is present within a predetermined short-distance range when the strength of the reflected wave is greater than a fixed threshold, and determines that an obstacle is present in a range farther than the short-distance range when the strength of the reflected wave is greater than both the fixed threshold and the CFAR threshold.

[0051] Fig. 12 is a diagram showing an example of the relationship between the envelope L, the fixed threshold Thf, and the CFAR threshold Thc when an obstacle is present in the second embodiment. Fig. 13 is a diagram showing an example of the relationship between the envelope L, the fixed threshold Thf, and the CFAR threshold Thc when an obstacle is not present in the second embodiment. A short distance range Rn is illustrated in Figs. 12 and 13. The short distance range Rn should be set appropriately depending on the specifications of the vehicle 1 and the performance of the transceiver unit 21, and may be, for example, a range within 1 m from the vehicle 1 (transceiver unit 21).

[0052] In this embodiment, the CFAR threshold Thc is not taken into consideration within the short distance range Rn, and the presence or absence of an obstacle is determined based on whether the intensity of the reflected wave is greater than the fixed threshold Thf. In the example shown in Fig. 12, since the peak P1 appearing within the short distance range Rn exceeds the fixed threshold Thf, it is determined that an obstacle is present.

[0053] In this embodiment, in an area farther than the short distance range Rn, the presence or absence of an obstacle is determined based on both the fixed threshold Thf and the CFAR threshold Thc, as in the first embodiment. In the example shown in Fig. 13, a peak P2 appearing in an area farther than the short distance range Rn exceeds the CFAR threshold Thc, but does not exceed the fixed threshold Thf, so it is determined that no obstacle is present.

[0054] 14 is a flowchart showing an example of processing in the object detection device 11 according to the second embodiment. In step S201, the transmitter / receiver 21 starts transmitting and receiving ultrasonic waves, and in step S202, the echo information generator 101 generates echo information indicating a time-series change in intensity of a reflected wave from an object present around the vehicle 1. In step S203, the threshold calculator 102 calculates a CFAR threshold Thc based on the echo information.

[0055] In step S204, the determination unit 103 determines whether the intensity I of the reflected wave acquired from the echo information is greater than a fixed threshold Thf (I>Thf). If I>Thf is not satisfied in step S204 (S204: No), it is determined that no obstacle is present, and this routine ends.

[0056] If I>Thf in step S204 (S204: Yes), the determination unit 103 determines in step S205 whether the distance corresponding to the peak determined to be I>Thf is within the short distance range Rn. If the distance is not within the short distance range Rn in step S205 (S205: No), the determination unit 103 determines in step S206 whether the intensity I of the reflected wave is greater than the CFAR threshold value Thc (I>Thc). If I>Thc is not true in step S206 (S206: No), it is determined that no obstacle is present, and this routine ends.

[0057] If it is determined in step S205 that the distance is within the short distance range Rn (S205: Yes), or if it is determined in step S206 that I>Thc (S206: Yes), the determination unit 103 determines in step S207 that an obstacle is present, and generates obstacle information regarding the obstacle. In step S208, the output unit 104 outputs the obstacle information to a mechanism such as the ECU 12.

[0058] As described above, according to this embodiment, within a predetermined short distance range, it is determined that an obstacle is present when the strength of the reflected wave is greater than the fixed threshold, and in a range farther than the short distance range, it is determined that an obstacle is present when the strength of the reflected wave is greater than the fixed threshold and the CFAR threshold. This is because in the short distance range, the fixed threshold can be set with relatively high accuracy, and there is little need to use the CFAR threshold. In this way, by limiting the range in which the CFAR threshold is used, the processing load for calculating the CFAR threshold, etc. can be reduced.

[0059] Third embodiment Fig. 15 is a diagram showing an example of a functional configuration of the object detection device 11 according to the third embodiment. As shown in Fig. 15, the control unit 22 of the object detection device 11 of this embodiment includes a reliability determination unit 201 in addition to the echo information generation unit 101, the threshold calculation unit 102, the determination unit 103, and the output unit 104 described above.

[0060] The reliability determining unit 201 determines the reliability of the determination result (obstacle information) by the determining unit 103 based on the difference between the intensity of the reflected wave corresponding to the obstacle and the fixed threshold value Thf, and generates reliability information indicating the reliability.

[0061] The output unit 104 of this embodiment associates the obstacle information generated by the determination unit 103 with the reliability information generated by the reliability determination unit 201, and outputs the information to a mechanism such as the ECU 12.

[0062] Fig. 16 is a diagram showing an example of the relationship between the envelope L, the fixed threshold Thf, and the CFAR threshold Thc when an obstacle is present in the third embodiment. Fig. 16 illustrates the difference ΔI between the intensity of the reflected wave of the peak P1 corresponding to the obstacle and the fixed threshold Thf.

[0063] The reliability determination unit 201 of this embodiment determines the reliability of the obstacle information regarding the obstacle corresponding to the peak P1 based on the difference ΔI between the intensity of the peak P1 that satisfies the condition for determining that the obstacle is an obstacle (here, the intensity of the reflected wave is greater than the fixed threshold value Thf and the CFAR threshold value Thc) and the fixed threshold value Thf. For example, the reliability can be determined so that it is higher as the difference ΔI is larger.

[0064] 17 is a flowchart showing an example of processing in the object detection device 11 according to the third embodiment. In step S301, the transmitter / receiver 21 starts transmitting and receiving ultrasonic waves, and in step S302, the echo information generator 101 generates echo information indicating a time-series change in intensity of a reflected wave from an object present around the vehicle 1. In step S303, the threshold calculator 102 calculates a CFAR threshold Thc based on the echo information.

[0065] In step S304, the determination unit 103 determines whether the intensity I of the reflected wave acquired from the echo information is greater than a fixed threshold Thf (I>Thf) and whether the intensity I is greater than a CFAR threshold Thc (I>Thc).

[0066] In step S304, if I>Thf and I>Thc are not satisfied (S304: No), that is, if the intensity I of the reflected wave is smaller than at least one of the fixed threshold Thf and the CFAR threshold Thc, it is determined that no obstacle is present, and this routine ends.

[0067] In step S304, if I>Thf and I>Thc (S304: Yes), in step S305, the determination unit 103 determines that an obstacle is present, and generates obstacle information related to the obstacle. In step S306, reliability information indicating the reliability of the obstacle information (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 in step S304) and the fixed threshold value Thf. In step S306, the output unit 104 outputs the obstacle information and the reliability information to a mechanism such as the ECU 12.

[0068] As described above, according to the present embodiment, reliability information indicating the reliability of the obstacle information is generated based on the difference between the intensity of the reflected wave and the fixed threshold value. By using such reliability information, it becomes possible to control the vehicle 1 based on the obstacle information with higher accuracy.

[0069] (Modification) In the above-described embodiment, an example has been given of a configuration in which ultrasonic waves are used as the waves transmitted and received to detect an obstacle, but the configuration of the object detection device is not limited to this. For example, a millimeter wave radar, a LiDAR (Light Detection and Ranging) sensor, etc. may be used.

[0070] Furthermore, in the above-described embodiment, it is assumed that the reflected wave is a direct wave transmitted and received by the same transceiver 21, but the reflected wave may be an indirect wave that is a transmission wave transmitted from one transceiver 21 (e.g., transceiver 21E) and received by another transceiver 21 (e.g., transceiver 21F). In this case, at least one of the fixed threshold and the CFAR threshold may be changed depending on whether the reflected wave is a direct wave or an indirect wave.

[0071] The program for causing a computer (such as the processor 43) to execute the process for realizing the functions of the object detection device described above can be provided by recording it in an installable or executable file format on a computer-readable recording medium such as a CD (Compact Disc)-ROM, a flexible disk (FD), a CD-R (Recordable), a DVD (Digital Versatile Disk), etc. The program may also be provided or distributed via a network such as the Internet.

[0072] Although the embodiment of the present invention has been described above, the above-mentioned embodiment and its modifications are merely examples and are not intended to limit the scope of the invention. The above-mentioned novel embodiment and modifications can be implemented in various forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. The above-mentioned embodiment and modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0073] 1...vehicle (moving object), 11...object detection device, 21, 21A to 21L...transmitter / receiver, 102...threshold value calculation unit, 103...determination unit, 201...reliability determination unit, O...obstacle, Thc...CFAR threshold value (variable threshold value), Thf...fixed threshold value

Claims

1. 1. An object detection device that detects an obstacle present around a moving body based on a time series change in intensity of a reflected wave generated when a transmission wave transmitted from the moving body is reflected by an object, comprising: a threshold calculation unit that calculates a variable threshold that varies in accordance with the movement of the moving object based on a moving average value of the intensity of the reflected wave; a determination unit that determines that the obstacle is present when the intensity of the reflected wave is greater than a predetermined fixed threshold and the variable threshold; An object detection device comprising:

2. The determination unit determines that the obstacle is present when the intensity of the reflected wave is greater than the fixed threshold within a predetermined short distance range, and determines that the obstacle is present when the intensity of the reflected wave is greater than the fixed threshold and the variable threshold within a range farther than the short distance range. The object detection device according to claim 1 .

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

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