Object detection device

Abstract

This object detection device is for detecting an obstacle present in the vicinity of a moving body on the basis of a time-series change in the intensity of reflected waves produced by transmission waves transmitted from the moving body being reflected by the object, and is provided with a threshold computation unit for calculating a variation threshold that varies in accordance with the movement of the moving body on the basis of the moving average value of the intensity of the reflected waves, and a determination unit that determines that an obstacle is present if the intensity of the reflected waves is greater than a predetermined fixed threshold and the variation threshold.

Description

Object detection device

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

[0002] Mobile objects such as vehicles use object detection devices that detect obstacles around the mobile object based on information such as time of flight (TOF) and Doppler shift obtained by transmitting and receiving ultrasonic waves. Such object detection devices utilize CFAR (Constant False Alarm Rate) processing as a technique for suppressing the influence of noise caused by reflected waves from objects that are not the target of detection (e.g., road surfaces). CFAR processing optimizes a threshold value for determining whether an object that reflects a reflected wave is an obstacle based on a moving average value of the intensity of the reflected wave, which changes over time, in accordance with the condition of the road surface, etc.

[0003] Japanese Patent Application Laid-Open No. 2016-206011

[0004] While the CFAR processing described above can generally suppress the effects of noise, it may be susceptible to noise depending on the situation. For example, if the road surface on which the mobile object is traveling is smooth, the threshold value is set low. Therefore, if a non-obstacle such as a small bump suddenly appears on such a road surface, the intensity of the reflected wave from the non-obstacle is likely to exceed the threshold value. In such a case, there is a high possibility that an obstacle will be erroneously determined to be present even when there is no obstacle.

[0005] The present invention has been made in view of the above, and provides an object detection device that can suppress erroneous detection of an obstacle.

[0006] An object detection device according to 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 reflected waves generated when a transmission wave transmitted from the moving body is reflected by an object, and is equipped with 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 variable threshold.

[0007] According to the present invention, it is possible to provide an object detection device that can suppress erroneous detection of an obstacle.

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

[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) Fig. 1 is a diagram showing an example of the configuration of a vehicle 1 according to a first embodiment. The vehicle 1 is an example of a moving body on which an object detection device according to this embodiment is mounted. The object detection device according to this embodiment is a device that detects obstacles present around the vehicle 1 based on information such as time of flight (TOF) 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 to 21L. Hereinafter, when there is no need to distinguish between the plurality of transceivers 21A to 21L, they may be referred to as a transceiver 21. Each transceiver 21 is installed on a vehicle body 2 that serves as the exterior of the 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 transmitted wave, and ultrasonic waves generated when the transmitted wave is reflected by an object may be referred to as a reflected wave.

[0012] 1, 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. 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 the 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 multiple transceivers 21 and a control unit 22. Each transceiver 21 includes a vibrator 31 configured using a piezoelectric element or the like, an amplifier, and the like, and transmits and receives ultrasonic waves through the vibration of the vibrator 31. Specifically, each transceiver 21 transmits ultrasonic waves generated in response to the vibration of the vibrator 31 as a transmission wave and detects the vibration of the vibrator 31 caused by the reflected waves of the transmission wave reflected by an object such as an obstacle O or a road surface G. The obstacle O is an object that is present around the vehicle 1 and is to be detected, and may be, for example, another vehicle, a roadside object, a wall, a person, a curb, a bollard, etc. The vibration of the vibrator 31 is converted into an electrical signal, and based on the electrical signal, the time of flight (TOF) corresponding to the distance from the transceiver 21 to the obstacle O, a Doppler shift corresponding to the relative velocity between the vehicle 1 and the obstacle O, and the like can be obtained.

[0015] 2 illustrates a configuration in which both transmission of the transmission wave and reception of the reflected wave are performed using a single oscillator 31, but the configuration of the transmitter / receiver 21 is not limited to this. For example, the transmitter and receiver may be separated, such as a configuration in which an oscillator for transmitting the transmission wave and an oscillator 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 (such as the transceiver unit 21 and the ECU 12). The storage device 42 includes a main storage device such as a read-only memory (ROM) or a random access memory (RAM), and an auxiliary storage device such as a hard disk drive (HDD) or a solid state drive (SSD). The processor 43 is an integrated circuit that executes various processes to realize 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), or a field programmable gate array (FPGA) that operates according to a program. The processor 43 executes various arithmetic and control processes by reading and executing 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 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 transmission and reception of information between the ECU 12 and external mechanisms (such as the object detection device 11, drive mechanism, braking mechanism, steering mechanism, transmission mechanism, in-vehicle display, speakers, 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 programs stored in the storage device 52 and executes various arithmetic and control processes.

[0018] Fig. 3 is a diagram showing an example of a distance calculation method using the TOF method according to the first embodiment. Fig. 3 illustrates an envelope curve L that indicates changes over time in the intensity (signal level) of ultrasonic waves transmitted and received by the transmitter-receiver 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 transmitter-receiver 21 (the magnitude of vibration of the transducer 31).

[0019] The envelope L shows the change over time in the intensity, which indicates the magnitude of the vibration of the vibrator 31. From the envelope L shown in Fig. 3, it can be seen that the vibrator 31 is driven to vibrate for a period of time Ta from time t0, completing the transmission of the transmission wave at time t1, and then the vibration of the vibrator 31 due to inertia continues while attenuating for a period of time Tb until time 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 time t4, a time Tp after the start of transmission of the transmission wave at time t0, when the magnitude of the vibration of the vibrator 31 reaches or exceeds a threshold value Th. This threshold value Th is a value set to distinguish whether the vibration of the vibrator 31 is caused by reception of a wave reflected from the obstacle O or reception of a wave reflected from an object other than the obstacle O (e.g., the road surface G). Note that although the threshold value Th is shown as a constant value here, the threshold value Th may also 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 reception of a wave reflected from the obstacle O.

[0021] In this example, the envelope curve L indicates that the vibration of the vibrator 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 transmitted wave last transmitted at the timing t1 returns as a reflected wave.

[0022] Furthermore, in envelope L, timing t3, which is the start point of the peak at timing t4, corresponds to the timing when reception of the reflected wave from obstacle O begins, in other words, the timing when the transmitted 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, which is the transmission time of the transmitted wave.

[0023] From the above, in order to use TOF to find the distance from the transmitter / receiver 21, which is the source of the ultrasonic waves, to the obstacle O, it is necessary to find the time Tf between the time t0 when the transmission of the transmitted wave begins and the time 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 time t0 and the time t4 when the intensity of the reflected wave exceeds the threshold Th and reaches its peak.

[0024] The time t0 when the transmission of the transmission wave begins can be easily identified as the time when the object detection device 200 starts operating, and the time Ta as the transmission time of the transmission wave is determined in advance by settings, etc. Therefore, by identifying the time t4 when the intensity of the reflected wave reaches a peak equal to or greater than the threshold value Th, the distance from the vehicle 1 (the transmitter / receiver 21, which is the source of the transmission and reception of the ultrasonic waves) to the obstacle O can be calculated. Note that the above calculation method is an example, and the distance from the vehicle 1 to the obstacle O may be calculated using any known or new method as appropriate.

[0025] 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 hardware and software (programs, etc.) of the object detection device 11 as shown in FIG. 2. Furthermore, at least some of these functional units may be realized by dedicated hardware (circuits).

[0026] The echo information generating unit 101 generates echo information indicating time-series changes 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 on 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 the CFAR threshold based on the moving average value.

[0028] The determination unit 103 determines whether or not an obstacle is present around the vehicle 1 based on the echo information, a predetermined fixed threshold, and the CFAR threshold calculated by the threshold calculation unit 102. In this embodiment, the determination unit 103 determines that an obstacle is present when the intensity of the reflected wave is greater than the fixed threshold and the CFAR threshold. If the determination unit 103 determines that an obstacle is present, it generates obstacle information related to the obstacle. The obstacle information may include, for example, the distance from the vehicle 1 (transmitter / receiver 21) to the obstacle, the relative speed of the obstacle, etc.

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

[0030] FIG. 5 is a diagram illustrating 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 predetermined time intervals. Then, a first sum Σ1 is calculated, which is the sum of the intensity values ​​of N samples of the reflected wave received during a first period Δt1 prior to a certain detection time t. A second sum Σ2 is calculated, which is the sum of the intensity values ​​of N samples of the reflected wave received during a second period Δt2 after the detection time t. A moving average value A is then calculated by adding the first sum Σ1 and the second sum Σ2 together to obtain a sum Σ, which is the sum of N samples in the first period Δt1 and N samples in the second period Δt2. A CFAR threshold value Thc is then 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 multiplying the moving average value A by a predetermined constant. The addition process is a process of adding a predetermined constant 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] Note that the method of calculating the CFAR threshold Thc is not limited to the above. For example, the above describes the CA (Cell Averaging)-CFAR process in which the moving average value A is the average of all values ​​corresponding to the periods Δt1 and Δt2 before and after the detection timing t, but the CFAR threshold Thc may also 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] 6 is a diagram illustrating 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 located 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 each distance from the vehicle 1. The fixed threshold Thf may be stored in advance in an appropriate storage device (e.g., the storage device 42) mounted on the vehicle 1. A specific method for setting the fixed threshold Thf should be determined appropriately depending on the specifications of the vehicle 1, the performance of the transceiver 21, and the like. However, the fixed threshold Thf may be set, for example, based on a statistical value (e.g., 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] 7 is a diagram illustrating an example of the CFAR threshold Thc when an obstacle is present in the first embodiment. In FIG. 7, an envelope L, a moving average value A of the envelope L, and the CFAR threshold Thc when an obstacle is present are illustrated.

[0035] The CFAR threshold value Thc shown here is a value obtained by integrating 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 fluctuate depending on the undulations of the road surface while the vehicle 1 is traveling. The strength of the reflected wave from an obstacle (peak P1) is usually greater than the CFAR threshold value Thc.

[0036] By using the CFAR threshold Thc as described above, the influence of noise due to undulations of the road surface and the like can basically be suppressed, but there is a possibility that the influence of noise may become greater depending on the situation.

[0037] 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 the 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 (e.g., a small step on the road surface) located 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, as in 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 bump appears on the road surface in such a state, the intensity of the reflected wave from the non-obstacle (peak P2) may become greater than the low 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] 9 is a diagram illustrating 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. In FIG. 9, a state is illustrated in which a peak P1 corresponding to the intensity of the reflected wave from the 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] 10 is a diagram illustrating 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. In FIG. 10, a peak P2 corresponding to the intensity of a reflected wave from a non-obstacle is greater than the CFAR threshold Thc but less than the fixed threshold Thf.

[0043] In this embodiment, as illustrated in FIG. 10, if 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. In step S102, the echo information generator 101 generates echo information indicating time-series changes in the intensity of reflected waves from objects present around the vehicle 1. In step S103, the threshold calculator 102 calculates the 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 value Thf and the CFAR threshold value Thc, it is determined that no obstacle is present, and this routine ends.

[0047] If I>Thf and I>Thc in step S104 (S104: Yes), the determination unit 103 determines that an obstacle is present in step S105 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 this embodiment, it is determined that an obstacle is present when the intensity of the reflected wave is greater than both the fixed threshold and the CFAR threshold, thereby reducing the possibility of false 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 if 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 if the strength of the reflected wave is greater than 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 no obstacle is present in the second embodiment. Figs. 12 and 13 illustrate an example of a short-distance range Rn. The short-distance range Rn should be set appropriately depending on the specifications of the vehicle 1, the performance of the transceiver unit 21, and the like, but 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 Figure 12, the peak P1 appearing within the short distance range Rn exceeds the fixed threshold Thf, so it is determined that an obstacle is present.

[0053] In this embodiment, in the region 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, peak P2 appearing in the region farther than the short distance range Rn exceeds the CFAR threshold Thc but does not exceed the fixed threshold Thf, and therefore 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. In step S202, the echo information generator 101 generates echo information indicating time-series changes in the intensity of reflected waves from objects present around the vehicle 1. In step S203, the threshold calculator 102 calculates the 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 obtained 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 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 related to 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 intensity 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 intensity of the reflected wave is greater than both 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, it is possible to reduce the processing load required for calculating the CFAR threshold, etc.

[0059] 15 is a diagram showing an example of the functional configuration of an object detection device 11 according to a 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, threshold calculation unit 102, determination unit 103, and output unit 104 described above.

[0060] The reliability determination unit 201 determines the reliability of the judgment result (obstacle information) by the judgment 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 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] 16 is a diagram illustrating 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. In FIG. 16, the difference ΔI between the intensity of the reflected wave of the peak P1 corresponding to the obstacle and the fixed threshold Thf is illustrated.

[0063] The reliability determination unit 201 of this embodiment determines the reliability of obstacle information regarding an obstacle corresponding to a peak P1 based on a difference ΔI between the intensity of the peak P1 that satisfies the conditions for determining that the peak P1 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 becomes higher as the difference ΔI becomes 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. In step S302, the echo information generator 101 generates echo information indicating time-series changes in the intensity of reflected waves from objects present around the vehicle 1. In step S303, the threshold calculator 102 calculates the 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 value Thf or the CFAR threshold value Thc, it is determined that no obstacle is present, and this routine ends.

[0067] If I>Thf and I>Thc in step S304 (S304: Yes), the determination unit 103 determines in step S305 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 this embodiment, reliability information indicating the reliability of 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] 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 obstacles, but the configuration of the object detection device is not limited to this. For example, a configuration in which millimeter-wave radar, a LiDAR (Light Detection and Ranging) sensor, or the like is used may also 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 unit 21. However, the reflected wave may be an indirect wave that is a transmission wave transmitted from one transceiver unit 21 (e.g., transceiver unit 21E) and received by another transceiver unit 21 (e.g., transceiver unit 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] A program that causes a computer (such as the processor 43) to execute processing for realizing the functions of the object detection device described above can be provided by being recorded in an installable or executable file on a computer-readable recording medium such as a CD (Compact Disc)-ROM, a flexible disk (FD), a CD-R (Recordable), or a DVD (Digital Versatile Disk). The program may also be provided or distributed via a network such as the Internet.

[0072] Although the embodiments of the present invention have been described above, the above-described embodiments and their modifications are merely examples and are not intended to limit the scope of the invention. The novel embodiments and modifications described above can be implemented in various forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The above-described embodiments and modifications are included within the scope and spirit of the invention, and are also included in the invention and its equivalents as defined in the claims.

[0073] 1...vehicle (moving body), 11...object detection device, 21, 21A to 21L...transmitter / receiver unit, 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. 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, the object detection device comprising: 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 the obstacle is present when the intensity of the reflected wave is greater than a predetermined fixed threshold and the variable threshold.

2. The object detection device of claim 1, wherein the determination unit determines that an 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 an obstacle is present when the intensity of the reflected wave is greater than both the fixed threshold and the variable threshold in a range farther than the short-distance range.

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

4. The object detection device according to claim 1 or 2, wherein the fixed threshold decreases linearly with an increase in the distance from the moving body to the object.

5. The object detection device according to claim 3, wherein the fixed threshold decreases linearly with an increase in the distance from the moving body to the object.

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

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

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