Object detection device

Abstract

To provide an object detection device having improved accuracy of detecting an object.SOLUTION: An object detection device comprises: a saving unit which stores in a storage unit as detection data, a distance based on one or more reflected waves each time one or more reflected waves are received in response to a transmitted wave transmitted from one of multiple transmission / reception units; an identification unit which, when a current reflected wave has predefined reliability, sets the detection data for the current reflection wave as reference detection data, calculates a retroactive amount on the basis of movement information for a mobile body from the time of reception of the previous reflected wave, and identifies detection data for the same object as the reference detection data from among a plurality of detection data stored in the storage unit; and a triangulation calculation unit which calculates an obstacle distance by triangulation, for each detection data that is identified at each transmission of the transmission wave.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to an object detection device. [Background technology]

[0002] In an object detection device that uses ultrasonic waves to detect obstacles present around a vehicle, a technology is used in which multiple transceivers that transmit and receive ultrasonic waves are installed on the vehicle body, and the distance from the vehicle to the obstacle is calculated based on the timing of transmission and reception of ultrasonic waves by each transceiver. In such a configuration with multiple transceivers, the reflected waves received by each transceiver (ultrasonic waves generated when ultrasonic waves transmitted from the transceiver (transmission waves) are reflected by an object) include direct waves and indirect waves.

[0003] A direct wave is a reflected wave corresponding to a transmitted wave transmitted from a certain transceiver unit and received by the same transceiver unit that transmitted the transmitted wave. An indirect wave is a reflected wave corresponding to a transmitted wave transmitted from a certain transceiver unit and received by a transceiver unit different from the transceiver unit that transmitted the transmitted wave.

[0004] As a technology using such direct waves and indirect waves, there is known a technology that estimates the distance to an obstacle by triangulation using a combination of a distance calculated based on a direct wave and a distance calculated based on an indirect wave.A known prior art technology using such triangulation is a technology that determines whether the previously calculated position information and the currently calculated position information correspond to the same object, based on the previously calculated triangulation position information and the currently calculated triangulation position information (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-80643 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in such conventional techniques, the accuracy of calculated position information decreases as the distance increases in triangulation. Therefore, in conventional techniques, if the accuracy of the previously calculated triangulation position information is low, the currently calculated triangulation position information may be determined to be a different object even if it is the same object as the previously calculated triangulation position information, resulting in a problem of reduced accuracy in detecting objects such as obstacles.

[0007] One of the problems to be solved by the embodiments of the present invention is to provide an object detection device that can improve the accuracy of detecting the position of an object. [Means for solving the problem]

[0008] An object detection device of an embodiment is an object detection device that is mounted on a moving body and detects obstacles present in the vicinity of the moving body, and includes a plurality of transmitter-receivers that transmit and receive ultrasonic waves, a calculation unit that calculates an obstacle distance, which is the distance from the moving body to the obstacle, based on the timing of transmission and reception of ultrasonic waves by each of the plurality of transmitter-receivers, and a memory unit.The calculation unit includes: a storage unit that, each time it receives one or more reflected waves in response to a transmission wave transmitted from any of the plurality of transmitter-receivers, stores the distance based on the one or more reflected waves in the memory unit as detection data; an identification unit that, if the current reflected wave has a predetermined reliability, uses the detection data of the current reflected wave as reference detection data, calculates a distance to go back based on movement information of the moving body from the time the previous reflected wave was received, and identifies detection data of the same object from the plurality of detection data stored in the memory unit based on the reference detection data and the distance to go back; and a triangulation calculation unit that calculates the obstacle distance by triangulation for each piece of detection data identified each time the transmission wave is transmitted. [Effects of the Invention]

[0009] According to the object detection device according to the embodiment, for example, it is possible to improve the accuracy of detecting the position of an object. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a vehicle according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of a vehicle control system according to the embodiment. [Figure 3] FIG. 3 is a diagram showing an example of a method for calculating distance using the TOF method. [Figure 4] FIG. 4 is a diagram illustrating an example of a functional configuration of the object detection device according to the embodiment. [Figure 5] FIG. 5 is a diagram illustrating an example of a first direct wave distance and a second direct wave distance according to the embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of a first indirect wave distance and a second indirect wave distance according to the embodiment. [Figure 7] FIG. 7 is a diagram illustrating an example of a waveform of a reflected wave according to the embodiment. [Figure 8] FIG. 8 is a diagram illustrating an example of waveforms of a plurality of reflected waves with respect to a transmitted wave according to the embodiment. [Figure 9] FIG. 9 is a diagram illustrating an example of the detection data according to the embodiment. [Figure 10] FIG. 10 is a diagram showing an example of the movement of the vehicle 1 according to the embodiment and the waveform of the reflected wave. [Figure 11] FIG. 11 is a flowchart illustrating an example of a procedure of the object detection process according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The configurations of the embodiments described below and the actions and effects brought about by the configurations are merely examples, and the present invention is not limited to the following description.

[0012] 1 is a diagram showing an example of the configuration of a vehicle 1 according to an embodiment. The vehicle 1 is an example of a moving body on which an object detection device according to the embodiment is mounted. The object detection device according to the 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.

[0013] 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 transceivers 21. Each transceiver 21 is installed on the vehicle body 2, which is 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 transmitted waves, and ultrasonic waves generated when the transmitted waves are reflected by an object may be referred to as reflected waves.

[0014] 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.

[0015] 2 is a diagram showing an example of the configuration of a vehicle control system 50 according to an embodiment. The vehicle control system 50 performs processing for controlling the vehicle 1 based on information output from the object detection device 200. The vehicle control system 50 according to this embodiment includes an ECU 100 and the object detection device 200.

[0016] The object detection device 200 includes a plurality of transmitter / receivers 21 and a control unit 220. Each transmitter / receiver 21 includes a vibrator 211 configured using a piezoelectric element or the like, an amplifier, etc., and realizes transmission and reception of ultrasonic waves by the vibration of the vibrator 211. Specifically, each transmitter / receiver 21 transmits ultrasonic waves generated in response to the vibration of the vibrator 211 as a transmission wave, and detects the vibration of the vibrator 211 caused by a wave reflected from the transmission wave by an object such as an obstacle O or the road surface. The vibration of the vibrator 211 is converted into an electrical signal, and based on the electrical signal, it is possible to obtain, for example, a time of flight (TOF) corresponding to the distance from the transmitter / receiver 21 to the obstacle O and Doppler shift information corresponding to the relative speed between the vehicle 1 and the obstacle O.

[0017] 2 illustrates a configuration in which both transmission of the transmission wave and reception of the reflected wave are performed using a single oscillator 211, 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.

[0018] The control unit 220 includes an input / output device 221, a storage device 222, and a processor 223. The input / output device 221 is an interface device that enables transmission and reception of information between the control unit 220 and external devices (such as the transceiver unit 21 and the ECU 100). The storage device 222 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 223 is an integrated circuit that executes various processes to realize the functions of the control unit 220, and may be configured using, for example, a central processing unit (CPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or the like that operates according to a program. The processor 223 executes various arithmetic and control processes by reading and executing programs stored in the storage device 222.

[0019] The ECU 100 is a unit that executes various processes for controlling the vehicle 1 based on information acquired from the object detection device 200 and the like. The ECU 100 includes an input / output device 110, a storage device 120, and a processor 130. The input / output device 110 is an interface device that enables transmission and reception of information between the ECU 100 and external mechanisms (such as the object detection device 200, drive mechanism, braking mechanism, steering mechanism, transmission mechanism, in-vehicle display, speakers, and various sensors). The storage device 120 includes a main storage device such as a ROM or RAM, and an auxiliary storage device such as an HDD or SSD. The processor 130 is an integrated circuit that executes various processes for realizing the functions of the ECU 100, and may be configured using, for example, a CPU, an ASIC, an FPGA, or the like. The processor 130 reads programs stored in the storage device 120 and executes various arithmetic and control processes.

[0020] Fig. 3 is a diagram showing an example of a distance calculation method using the TOF method. Fig. 3 illustrates an envelope L11 (echo information) that indicates a change over time in the intensity (signal level) of the 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 the ultrasonic waves transmitted and received by the transmitting and receiving unit 21 (the magnitude of vibration of the transducer 211).

[0021] Envelope L11 shows the change over time in intensity, which indicates the magnitude of vibration of oscillator 211. From envelope L11 shown in Fig. 3, it can be seen that oscillator 211 is driven to vibrate for time Ta from time t0, completing transmission of the transmission wave at time t1, and then the vibration of oscillator 211 due to inertia continues while attenuating for time Tb until time t2. Therefore, in the graph shown in Fig. 3, time Tb corresponds to the so-called reverberation time.

[0022] The envelope L11 reaches a peak at time t4, which is a time Tp after time t0 when the transmission of the transmission wave starts, at which time the magnitude of the vibration of the vibrator 211 reaches or exceeds the detection threshold Ith. This detection threshold Ith is a value set to distinguish whether the vibration of the vibrator 211 is caused by the reception of a reflected wave from an obstacle O (another vehicle, a structure, a pedestrian, etc.) or by the reception of a reflected wave from an object other than the obstacle O (for example, the road surface, etc.). Note that although the detection threshold Ith is shown as a constant value here, the detection threshold Ith may also be a variable value that changes depending on the situation. Vibrations having a peak equal to or greater than the detection threshold Ith can be considered to be caused by the reception of a reflected wave from the obstacle O.

[0023] The envelope L11 in this example shows that the vibration of the vibrator 211 attenuates after timing t4. Therefore, timing t4 corresponds to the timing at which reception of the reflected wave from the obstacle O is completed, in other words, the timing at which the transmission wave last transmitted at timing t1 returns as a reflected wave.

[0024] Furthermore, in envelope L11, 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.

[0025] From the above, in order to use TOF to find the distance from the transmitter / receiver unit 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 detection threshold Ith and reaches its peak.

[0026] The time t0 when the transmission wave starts to be transmitted can be easily identified as the time 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 time t4 when the intensity of the reflected wave reaches a peak equal to or exceeds the detection threshold Ith, the distance from the vehicle 1 (the transmitter / receiver 21, which is the source of the ultrasonic wave transmission and reception) to the obstacle O can be calculated.

[0027] The above calculation method is merely an example, and the distance from the vehicle 1 to the obstacle O may be calculated using any known or new method as appropriate.

[0028] 4 is a diagram showing an example of the functional configuration of the object detection device 200 according to the embodiment. The object detection device 200 according to the present embodiment includes a calculation unit 301, the above-described storage device 222, and a plurality of transmission / reception units 21 (21A to 21L).

[0029] The calculation unit 301 calculates the obstacle distance, which is the distance from the vehicle 1 to the obstacle O, based on the timing of transmission and reception of ultrasonic waves by each transceiver unit 21. The reflected waves received by each transceiver unit 21 according to this embodiment include direct waves and indirect waves. A direct wave is a reflected wave corresponding to a transmission wave transmitted from a certain transceiver unit 21 (e.g., transceiver unit 21A) and received by the same transceiver unit 21 (e.g., transceiver unit 21A) as the transceiver unit 21 that transmitted the transmission wave. An indirect wave is a reflected wave corresponding to a transmission wave transmitted from a certain transceiver unit 21 (e.g., transceiver unit 21A) and received by a transceiver unit 21 (e.g., transceiver unit 21B) different from the transceiver unit 21 that transmitted the transmission wave. The calculation unit 301 according to this embodiment calculates the obstacle distance using both the reception timing of the direct wave and the reception timing of the indirect wave.

[0030] As shown in Fig. 4, the calculation unit 301 according to this embodiment includes a direct wave distance calculation unit 311, an indirect wave distance calculation unit 312, a storage unit 313, an identification unit 315, and a triangulation calculation unit 314. These functional units can be realized, for example, by cooperation between hardware and software (programs, etc.) of the object detection device 200 shown in Fig. 2. Furthermore, at least some of these functional units may be realized by dedicated hardware (circuits).

[0031] When a reflected wave of a transmission wave transmitted from a first transceiver unit (e.g., 21A) that is one of the multiple transceivers 21 is received by the first transceiver unit, the direct wave distance calculation unit 311 calculates a first direct wave distance based on the timing at which the transmission wave was transmitted from the first transceiver unit and the timing at which the reflected wave (direct wave) of the transmission wave was received by the first transceiver unit. Also, when a reflected wave of a transmission wave transmitted from a second transceiver unit (e.g., 21B) different from the first transceiver unit is received by the second transceiver unit, the direct wave distance calculation unit 311 calculates a second direct wave distance based on the timing at which the transmission wave was transmitted from the second transceiver unit and the timing at which the reflected wave (direct wave) of the transmission wave was received by the second transceiver unit. That is, the first direct wave distance is calculated based on the direct wave received by the first transceiver unit, and the second direct wave distance is calculated based on the direct wave received by the second transceiver unit.

[0032] When a reflected wave of a transmission wave transmitted from a third transceiver unit (e.g., 21A) that is one of the multiple transceivers 21 is received by a fourth transceiver unit (e.g., 21B) different from the third transceiver unit, the indirect wave distance calculation unit 312 calculates a first indirect wave distance based on the timing at which the transmission wave was transmitted from the third transceiver unit and the timing at which the reflected wave (indirect wave) of the transmission wave was received by the fourth transceiver unit. Also, when a reflected wave of a transmission wave transmitted from the fourth transceiver unit is received by the third transceiver unit, the indirect wave distance calculation unit 312 calculates a second indirect wave distance based on the timing at which the transmission wave was transmitted from the fourth transceiver unit and the timing at which the reflected wave (indirect wave) of the transmission wave was received by the third transceiver unit. That is, the first indirect wave distance is calculated based on the indirect wave transmitted from the third transceiver unit and received by the fourth transceiver unit, and the second indirect wave distance is calculated based on the indirect wave transmitted from the fourth transceiver unit and received by the third transceiver unit.

[0033] Fig. 5 is a diagram showing an example of a first direct wave distance Dd1 and a second direct wave distance Dd2 according to an embodiment. Fig. 5 illustrates a situation in which two transceivers 21G and 21H installed at the rear of a vehicle 1 are defined as a first transceiver and a second transceiver, respectively, and an obstacle O is present behind the vehicle 1. Fig. 5 also illustrates a first transmission wave Wt1 transmitted from the first transceiver 21G and a first direct wave Wd1 resulting from the first transmission wave Wt1 being reflected by the obstacle O and received by the first transceiver 21G. Fig. 5 also illustrates a second transmission wave Wt2 transmitted from the second transceiver 21H and a second direct wave Wd2 resulting from the second transmission wave Wt2 being reflected by the obstacle O and received by the second transceiver 21H.

[0034] The first direct wave distance Dd1 is calculated based on the timing when the first transmission wave Wt1 is transmitted from the first transceiver 21G and the timing when the first direct wave Wd1 is received by the first transceiver 21G. The second direct wave distance Dd2 is calculated based on the timing when the second transmission wave Wt2 is transmitted from the second transceiver 21H and the timing when the second direct wave Wd2 is received by the second transceiver 21H.

[0035] Fig. 6 is a diagram showing an example of a first indirect wave distance Di1 and a second indirect wave distance Di2 according to the embodiment. Fig. 6 illustrates a situation in which two transceivers 21G and 21H installed at the rear of the vehicle 1 are respectively a third transceiver and a fourth transceiver, and an obstacle O is present behind the vehicle 1. Note that, here, a case is illustrated in which the first transceiver and the third transceiver are the same transceiver 21G, and the second transceiver and the fourth transceiver are the same transceiver 21H, but the present invention is not limited to this.

[0036] 6 illustrates a situation in which the fourth transceiver 21H receives a first indirect wave Wi1 and the third transceiver 21G receives a second indirect wave Wi2. The first indirect wave Wi1 is a reflected wave generated when the first transmission wave Wt1 transmitted from the third transceiver 21G is reflected by an obstacle O. The second indirect wave Wi2 is a reflected wave generated when the second transmission wave Wt2 transmitted from the fourth transceiver 21H is reflected by an obstacle O.

[0037] The first indirect wave distance Di1 is calculated based on the timing when the third transmission wave Wt1 is transmitted from the first transceiver 21G and the timing when the first indirect wave Wi1 is received by the fourth transceiver 21H. The second indirect wave distance Di2 is calculated based on the timing when the second transmission wave Wt2 is transmitted from the fourth transceiver 21H and the timing when the second indirect wave Wi2 is received by the third transceiver 21G.

[0038] 4, every time the storage unit 313 receives one or more reflected waves in response to a transmission wave transmitted from one of the multiple transmission / reception units 21, the storage unit 313 stores the distance based on the one or more reflected waves as detection data in the storage device 222. Here, the storage device 222 is an example of a storage unit.

[0039] Specifically, when the reflected waves are direct waves, the storage unit 313 stores the distances calculated by the direct wave distance calculation unit 311 for each of the one or more direct waves as detection data in the storage device 22. When the reflected waves are indirect waves, the storage unit 313 stores the distances calculated by the indirect wave distance calculation unit 312 for each of the one or more indirect waves as detection data in the storage device 22. Details of the detection data will be described later.

[0040] If the current reflected wave has a predetermined reliability, the identification unit 315 uses the detection data of the current reflected wave as reference detection data, and calculates the amount of tracing back based on movement information of the vehicle 1 from the time of receiving the previous reflected wave (for example, the speed and travel time of the vehicle 1).The identification unit 315 then identifies detection data of the same object from among the multiple detection data stored in the storage device 222 based on the reference detection data and the amount of tracing back.

[0041] More specifically, the identification unit 315 identifies the detection data related to the reflected wave received at a timing that is the calculated distance back from the reception timing of the current reflected wave as detection data of the same object based on the reference detection data and the distance back.

[0042] Here, if the intensity of the current reflected wave exceeds a predetermined threshold, the identifying unit 315 determines that the current reflected wave has a predetermined reliability (i.e., high reliability). More specifically, the predetermined threshold is an automatic threshold that varies depending on the intensity. Then, if the intensity of the current reflected wave exceeds the automatic threshold by a predetermined amount or more, the identifying unit 315 determines that the current reflected wave has a predetermined reliability.

[0043] Here, a value exceeding the automatic threshold by a predetermined amount is referred to as the reliability threshold. Therefore, when the intensity of the current reflected wave exceeds the reliability threshold, the identifying unit 315 determines that the current reflected wave has a predetermined reliability.

[0044] 7 is a diagram showing an example of a waveform of a reflected wave according to an embodiment. In FIG. 7, the vertical axis represents the intensity of the reflected wave, and the horizontal axis represents the distance. In FIG. 7, the waveform of the reflected wave is shown by a solid line, the automatic threshold is shown by a dotted line, and the reliability threshold is shown by a two-dot chain line.

[0045] In the example shown in FIG. 7, the identifying unit 315 determines that the reflected wave indicated by the arrow that exceeds the reliability threshold has a predetermined reliability, that is, has high reliability.

[0046] Fig. 8 is a diagram showing an example of waveforms of multiple reflected waves from a transmitted wave according to an embodiment. In Fig. 8, the vertical axis represents the intensity of the reflected wave, and the horizontal axis represents the distance. In Fig. 7, the waveforms of the reflected waves are shown by solid lines, and the automatic threshold is shown by dotted lines. In the example waveforms in Fig. 8, the two reflected waves that exceed the automatic threshold are referred to as Wave 1 and Wave 2, from left to right.

[0047] 9 is a diagram illustrating an example of detection data according to an embodiment. In the example of Fig. 9, the transmitted wave, the number of the reflected wave received in response to one transmitted wave (i.e., 1st wave, 2nd wave, 3rd wave, etc.), and the distance calculated based on the reflected wave are recorded as the detection data.

[0048] The detection data in Fig. 9 corresponds to the reflected waves in Fig. 8. The first and second reflected waves in Fig. 8 correspond to the distance of the first wave, "1.5 m," and the distance of the second wave, "1.7 m," respectively, indicated by the arrow of the reflected wave of the second (previous) transmitted wave in the detection data in Fig. 9. In the example of Figure 8, since the second reflected wave of the third (current) transmitted wave has a predetermined reliability (i.e., high reliability), the identification unit 315 sets the distance "1.7 m", which is the detection data of the second wave, as the reference detection data.

[0049] Fig. 10 is a diagram showing an example of the movement of vehicle 1 and the waveform of the reflected wave in the embodiment. Assume that vehicle 1 moves from the left position shown in Fig. 10(b) to the left position shown in Fig. 10(a). The waveforms of the reflected wave at this time are shown on the right side of Fig. 10(a) and (b), respectively.

[0050] The identification unit 315 calculates the distance traveled by the vehicle 1 from the travel speed and travel time of the vehicle 1, and sets this value as the distance traveled back. Here, in the example of the detection data in FIG. 9, let us say that the calculated distance traveled back is 4 m. In this case, the identification unit 315 identifies the detection data with a distance of "2.1 m" obtained by adding the distance traveled back, 4 m, to the detection data of the second wave of the reflected wave of the third (current) transmission wave, which is the reference detection data, "1.7 m" (i.e., the detection data of the third wave indicated by the arrow among the reflected waves from the second (previous) transmission wave) as the detection data of the same object as the object detected in the second wave of the reflected wave of the third (current) transmission wave. The identification unit 315 then eliminates reflected waves other than the third wave, assuming that they are reflected waves from the road surface or the like other than the obstacle. This makes it possible to identify reflected waves from the same obstacle.

[0051] 4, the triangulation calculation unit 314 calculates the obstacle distance by triangulation for each piece of detection data identified each time a transmission wave is transmitted. Here, triangulation is sometimes called trilateration.

[0052] Specifically, when the first direct wave distance and the second direct wave distance shown in FIG. 5 have been calculated by the direct wave distance calculation unit 311, the triangulation calculation unit 314 calculates the obstacle distance by triangulation for each piece of detection data identified as detection data of the same object based on the first direct wave distance and the second direct wave distance.

[0053] Furthermore, when the first indirect wave distance and the second indirect wave distance shown in FIG. 6 have been calculated by the indirect wave distance calculation unit 312, the triangulation calculation unit 314 calculates the obstacle distance by triangulation for each piece of detection data identified as detection data of the same object based on the first indirect wave distance and the second indirect wave distance.

[0054] Furthermore, when the first direct wave distance shown in Figure 5 is calculated by the direct wave distance calculation unit 311 and the second indirect wave distance shown in Figure 6 is calculated by the indirect wave distance calculation unit 312, the triangulation calculation unit 314 calculates the obstacle distance by triangulation for each piece of detection data identified as detection data of the same object based on the first direct wave distance and the second indirect wave distance.

[0055] The triangulation calculation unit 314 outputs the calculated obstacle distance to the ECU 100, etc., and the calculated obstacle distance is used for various vehicle controls, etc.

[0056] Next, the object detection process according to this embodiment configured as above will be described. FIG. 11 is a flowchart illustrating an example of a procedure of the object detection process according to the embodiment. First, the transmitting / receiving unit 21 transmits a transmission wave and starts measuring the distance (S11). Next, the storage unit 313 determines whether the transmitting / receiving unit 21 has received a direct wave or an indirect wave as a reflected wave of the transmitted wave (S12). If the transmitting / receiving unit 21 has not received a direct wave or an indirect wave (S12: No), the process ends.

[0057] On the other hand, if a direct wave or an indirect wave is being received (S12: Yes), the following processing is executed for each of the direct wave and the indirect wave.

[0058] That is, when a direct wave is received, the direct wave distance calculation unit 311 calculates the distance to the object, and when an indirect wave is received, the indirect wave distance calculation unit 312 calculates the distance to the object. Then, the storage unit 313 stores the calculated distance for each reflected wave as detection data in the storage device 222 (S13).

[0059] Next, the identification unit 315 determines whether the reliability of the current reflected wave is high, that is, whether the current reflected wave has a predetermined reliability (S14). If the current reflected wave does not have the predetermined reliability and is therefore low (S14: No), the process ends.

[0060] On the other hand, if the current reflected wave has a predetermined reliability and is highly reliable (S14: Yes), the identification unit 315 sets the detection data of the current reflected wave as the reference detection data (S15).Then, the identification unit 315 calculates the amount of retrogression from the movement information of the vehicle 1 (S16).

[0061] Next, the identification unit 315 identifies the detection data that is the same object as the object at the distance of the reference detection data, as described above, from the calculated amount of tracing back and the detection data stored in the storage device 222 (S17).

[0062] Next, the triangulation calculation unit 314 calculates the obstacle distance for each identified detection data, i.e., for each measurement of the same object, by triangulation (S18). Next, the triangulation calculation unit 314 calculates the reliability of the object from the triangulation points (S19).

[0063] Here, the reliability can be calculated by, for example, a method described in Patent Document 1, in which a high reliability is assigned when an obstacle is detected. However, the reliability calculation is not limited to this.

[0064] As described above, the object detection device 200 of this embodiment includes a storage unit 313 that stores the distance based on one or more reflected waves as detection data in the storage unit 222 each time it receives one or more reflected waves in response to a transmission wave transmitted from any of the multiple transmission / reception units 21; an identification unit 315 that, if the current reflected wave has a predetermined reliability, uses the detection data of the current reflected wave as reference detection data, calculates the amount of retrogression based on movement information of the moving body from the time the previous reflected wave was received, and identifies detection data of the same object from the multiple detection data stored in the storage unit 222 based on the amount of retrogression; and a triangulation calculation unit 314 that calculates the obstacle distance by triangulation for each piece of detection data identified each time a transmission wave is transmitted.

[0065] Therefore, according to this embodiment, the previous reflected wave is identified based on the distance traveled by vehicle 1 from the current reliable reflected wave detection data, and the detection data of the same object is identified, and then the obstacle distance is calculated by triangulation, thereby improving the accuracy of detecting the position of the obstacle.

[0066] Furthermore, in the object detection device 200 according to this embodiment, the identification unit 315 identifies detection data relating to a reflected wave received at a timing that is the tracing amount prior to the reception timing of the current reflected wave as detection data of the same object based on the reference detection data and the tracing amount. Therefore, according to this embodiment, the reliable detection data of the current reflected wave is traced back the tracing amount for the movement of the vehicle 1 to identify the previous reflected wave and identify detection data of the same object, and then the obstacle distance is calculated by triangulation, thereby improving the detection accuracy of the obstacle position.

[0067] Furthermore, in the object detection device 200 according to this embodiment, the identification unit 315 determines that the current reflected wave has a predetermined reliability if the intensity of the current reflected wave exceeds a predetermined threshold. Therefore, according to this embodiment, if the current reflected wave has the predetermined reliability, the previous reflected wave is identified based on the amount of time traveled back from the detection data of the current reflected wave to the movement of the vehicle 1, and the detection data of the same object is identified, and the obstacle distance is then calculated by triangulation, thereby further improving the detection accuracy of the obstacle position.

[0068] Furthermore, in the object detection device 200 according to this embodiment, the predetermined threshold is an automatic threshold that varies depending on the intensity, and the identification unit 315 determines that the current reflected wave has a predetermined reliability when the intensity of the current reflected wave exceeds the automatic threshold by a predetermined amount or more. Therefore, according to this embodiment, reliable current reflected waves can be identified more accurately, thereby further improving the accuracy of detecting the position of an obstacle.

[0069] In addition, the object detection device 200 of this embodiment further includes a direct wave distance calculation unit 311 that, when a reflected wave of a transmission wave transmitted from a first transmission / reception unit 21, which is one of the multiple transmission / reception units 21, is received by the first transmission / reception unit 21 and a reflected wave of a transmission wave transmitted from a second transmission / reception unit 21 different from the first transmission / reception unit 21 is received by the second transmission / reception unit 21, calculates a first direct wave distance based on the timing at which the transmission wave was transmitted from the first transmission / reception unit 21 and the timing at which the reflected wave of the transmission wave was received by the first transmission / reception unit 21, and a second direct wave distance based on the timing at which the transmission wave was transmitted from the second transmission / reception unit 21 and the timing at which the reflected wave of the transmission wave was received by the second transmission / reception unit 21, and the triangulation calculation unit 314 calculates the obstacle distance by triangulation for each piece of detection data identified as detection data of the same object based on the first direct wave distance and the second direct wave distance. Therefore, according to this embodiment, the detection accuracy of the obstacle position can be further improved by using detection data that is identified as detection data of the same object based on the first direct wave distance and the second direct wave distance.

[0070] Furthermore, the object detection device 200 according to this embodiment further includes an indirect wave distance calculation unit 312 that, when the reflected wave of the transmission wave transmitted from the first transmission / reception unit 21 is received by the second transmission / reception unit 21 and the reflected wave of the transmission wave transmitted from the second transmission / reception unit 21 is received by the first transmission / reception unit 21, calculates a first indirect wave distance based on the timing at which the transmission wave was transmitted from the first transmission / reception unit 21 and the timing at which the reflected wave of the transmission wave was received by the second transmission / reception unit 21, and a second indirect wave distance based on the timing at which the transmission wave was transmitted from the second transmission / reception unit 21 and the timing at which the reflected wave of the transmission wave was received by the first transmission / reception unit 21, and the triangulation calculation unit 314 further calculates an obstacle distance by triangulation for each piece of detection data identified as detection data of the same object based on the first indirect wave distance and the second indirect wave distance. Therefore, according to this embodiment, the detection accuracy of the obstacle position can be further improved by using detection data that is identified as detection data of the same object based on the first direct wave distance and the second indirect wave distance.

[0071] Furthermore, in the object detection device 200 according to this embodiment, the triangulation calculation unit 314 further calculates the obstacle distance by triangulation for each piece of detection data identified as the detection data of the same object based on the first direct wave distance and the second indirect wave distance. Therefore, according to this embodiment, by using the detection data identified as the detection data of the same object based on the first direct wave distance and the second indirect wave distance, it is possible to further improve the detection accuracy of the obstacle position.

[0072] A program that causes a computer (such as processor 223) to execute processing for realizing the functions of object detection device 200 can be provided by being recorded 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), or a DVD (Digital Versatile Disk). The program may also be provided or distributed via a network such as the Internet.

[0073] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0074] 1...vehicle, 2...vehicle body, 21, 21A to 21L...transmitter / receiver unit, 50...vehicle control system, 100...ECU, 200...object detection device, 211...vibrator, 220...control unit, 221...input / output device, 222...storage device, 223...processor, 301...calculation unit, 311...direct wave distance calculation unit, 312...indirect wave distance calculation unit, 313...storage unit, 314...triangulation calculation unit, 315...identification unit, D0...installation distance, Dd1...first direct wave distance, Dd2...second direct wave distance, Di1...first indirect wave distance, Di2...second indirect wave distance, Wd1...first direct wave, Wd2...second direct wave, Wt1...first transmitted wave, Wt2...second transmitted wave, O...obstacle.

Claims

1. An object detection device mounted on a moving body and detecting an obstacle present around the moving body, a plurality of transmitting and receiving units for transmitting and receiving ultrasonic waves; a calculation unit that calculates an obstacle distance, which is a distance from the moving object to the obstacle, based on the timing of transmission and reception of ultrasonic waves by each of the plurality of transmission and reception units; a storage unit, The calculation unit a storage unit configured to store, in the storage unit as detection data, a distance based on one or more reflected waves received in response to a transmission wave transmitted from any one of the plurality of transmission / reception units, the one or more reflected waves; an identification unit that, when the current reflected wave has a predetermined reliability, uses the detection data of the current reflected wave as reference detection data, calculates a distance traveled based on movement information of the moving object from the time of receiving the previous reflected wave, and identifies detection data of the same object from the multiple detection data stored in the storage unit based on the reference detection data and the distance traveled; a triangulation calculation unit that calculates the obstacle distance by triangulation for each piece of detection data identified each time the transmission wave is transmitted; An object detection device comprising:

2. the identification unit identifies detection data relating to the reflected wave received at a timing that is the distance back from the reception timing of the current reflected wave as detection data of the same object based on the reference detection data and the distance back. The object detection device according to claim 1 .

3. The identification unit determines that the current reflected wave has a predetermined reliability when the intensity of the current reflected wave exceeds a predetermined threshold. The object detection device according to claim 1 .

4. the predetermined threshold is an automatic threshold that varies depending on the intensity, the identifying unit determines that the current reflected wave has a predetermined reliability when the intensity of the current reflected wave exceeds the automatic threshold by a predetermined amount or more. The object detection device according to claim 3 .

5. The calculation unit a direct wave distance calculation unit that, when a reflected wave of a transmission wave transmitted from a first transceiver unit that is one of the plurality of transceivers is received by the first transceiver unit and a reflected wave of a transmission wave transmitted from a second transceiver unit different from the first transceiver unit is received by the second transceiver unit, calculates a first direct wave distance based on the timing at which the transmission wave was transmitted from the first transceiver unit and the timing at which the reflected wave of the transmission wave was received by the first transceiver unit, and a second direct wave distance based on the timing at which the transmission wave was transmitted from the second transceiver unit and the timing at which the reflected wave of the transmission wave was received by the second transceiver unit, the triangulation calculation unit calculates the obstacle distance by triangulation for each of the specified detection data based on the first direct wave distance and the second direct wave distance. The object detection device according to claim 1 .

6. The calculation unit an indirect wave distance calculation unit that, when a reflected wave of a transmission wave transmitted from the first transmission / reception unit is received by the second transmission / reception unit and a reflected wave of the transmission wave transmitted from the second transmission / reception unit is received by the first transmission / reception unit, calculates a first indirect wave distance based on a timing at which the transmission wave is transmitted from the first transmission / reception unit and a timing at which the reflected wave of the transmission wave is received by the second transmission / reception unit, and a second indirect wave distance based on a timing at which the transmission wave is transmitted from the second transmission / reception unit and a timing at which the reflected wave of the transmission wave is received by the first transmission / reception unit, the triangulation calculation unit further calculates the obstacle distance by the triangulation for each of the specified detection data based on the first indirect wave distance and the second indirect wave distance. The object detection device according to claim 5 .

7. the triangulation calculation unit further calculates the obstacle distance by triangulation for each of the detection data based on the first direct wave distance and the second indirect wave distance. The object detection device according to claim 6 .

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