JP2019143976A - Detection sensor, sensor system, and detection method - Google Patents

Abstract

To enable the performance of determining the presence of a detection target to be improved.SOLUTION: An acquisition unit 4 acquires one or a plurality of received wave signals Sig1. The one or a plurality of received wave signals Sig1 indicate information relating to the waveforms of one or a plurality of reflected waves W2 generated as the transmitted one or plurality of detection waves W1 are reflected by an object 7. A determination unit 5 determines the presence of a detection target on the basis of the one or a plurality of received wave signals Sig1 acquired by the acquisition unit 4. An output unit 6 outputs the determination result of the determination unit 5. When the object 7 has a three-dimensional shape where the surface inclination of the object is a specific inclination, the determination unit 5 determines on the basis of the one or a plurality of received wave signals Sig1 that there is no detection target.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a detection system, a sensor system, and a detection method. More specifically, the present disclosure relates to a detection system that determines whether a detection target exists, a sensor system that includes the detection system, and a detection method that determines whether a detection target exists.

  An ultrasonic sensor described in Patent Document 1 is illustrated as a conventional example. The ultrasonic sensor described in Patent Literature 1 includes a microphone and a calculation unit. The microphone intermittently transmits ultrasonic waves and receives reflected ultrasonic waves reflected by the object. The calculation unit performs a comparison process that compares the signal element of the reflected ultrasonic wave with the threshold value, determines that the object exists when the signal element is equal to or greater than the threshold value, and determines that the object is present when the signal element is less than the threshold value. Judge that it does not exist.

Japanese Patent Laying-Open No. 2015-025712

  In a system including an apparatus for determining the presence or absence of an object (detection target) such as the ultrasonic sensor described in Patent Document 1, it has been desired to further improve the performance of determining the presence or absence of an object.

  It is an object of the present disclosure to provide a detection system, a sensor system, and a detection method that can improve the performance of determining whether a detection target exists.

  In order to solve the above problem, a detection system according to an aspect of the present disclosure includes an acquisition unit, a determination unit, and an output unit. The acquisition unit acquires one or a plurality of received signals. The one or more received signals indicate information on the waveform of the one or more reflected waves generated by reflecting the transmitted one or more detected waves on the object. A determination part determines the presence or absence of a detection target based on the 1 or several received signal acquired in the acquisition part. The output unit outputs the determination result of the determination unit. The determination unit determines that there is no detection target based on one or a plurality of received signals when the object has a three-dimensional shape with a specific inclination of the surface of the object.

  A sensor system according to an aspect of the present disclosure includes a detection system and a sensor. The sensor transmits one or a plurality of detection waves, converts the one or a plurality of reflected waves into one or a plurality of received signals, and outputs them to the acquisition unit.

  A detection method according to an aspect of the present disclosure includes an acquisition step, a determination step, and an output step. In the acquisition step, one or a plurality of received signals are acquired. The one or more received signals indicate information on the waveform of the one or more reflected waves generated by reflecting the transmitted one or more detected waves on the object. In the determination step, the presence / absence of the detection target is determined based on the one or more received signals acquired in the acquisition step. In the output step, the determination result in the determination step is output. In the determination step, when the object has a three-dimensional shape with a specific inclination of the surface of the object, it is determined that there is no detection target based on one or a plurality of received signals.

  According to the detection system, the sensor system, and the detection method according to an aspect of the present disclosure, it is possible to improve the performance of determining whether or not a detection target exists.

FIG. 1 is a block diagram of a sensor system according to an embodiment. 2A to 2D are side views of a vehicle provided with the above sensor system. 3A and 3B are plan views of a vehicle provided with the above sensor system. 4A and 4B are graphs showing a waveform of a received signal in the sensor system of the above. FIG. 5 is a flowchart showing an operation example of the above-described sensor system.

  Hereinafter, a detection system, a sensor system, and a detection method according to embodiments will be described with reference to the drawings. However, the embodiments described below are only some of the various embodiments of the present disclosure. The following embodiment can be variously modified according to the design or the like as long as the object of the present disclosure can be achieved.

(Configuration of sensor system)
As shown in FIG. 1, the sensor system 1 of this embodiment includes a sensor 2 and a detection system 3. The sensor 2 has a plurality (two in FIG. 1) of sensor units 20. The sensor system 1 is provided in a vehicle 10 such as an automobile (see FIG. 2A), for example. The detection system 3 includes an acquisition unit 4, a determination unit 5, and an output unit 6.

  Each of the plurality of sensor units 20 includes a wave transmission unit 21 and a wave reception unit 22. The wave transmission unit 21 transmits the detection wave W1 intermittently (for example, at intervals of 200 ms). The detection wave W1 is, for example, an ultrasonic wave. The wave receiving unit 22 receives a reflected wave W <b> 2 that is generated when the detection wave W <b> 1 is reflected by the object 7. Thereby, the sensor system 1 can detect the object 7 present around the vehicle 10. The wave receiver 22 converts the reflected wave W2 into a received signal Sig1 and outputs it to the acquisition unit 4. The received signal Sig1 is a signal indicating information regarding the waveform of the reflected wave W2. More specifically, the received signal Sig1 is a signal obtained by converting the reflected wave W2 into an electric signal. The detection wave W1 is not limited to an ultrasonic wave, and may be a radio wave such as a millimeter wave radar.

  The sensor system 1 is configured not to detect an object 7 having a specific three-dimensional shape. More specifically, the object 7 having a three-dimensional shape in which the inclination of the surface of the object 7 is a specific inclination with respect to the road where the vehicle 10 exists corresponds to the object 7 having a specific three-dimensional shape. In the following description, the object 7 whose surface inclination is a specific inclination with respect to the road on which the vehicle 10 exists is referred to as a “specific object 71” and is detected by the sensor system 1 among the objects 7 other than the specific object 71. The object 7 to be detected may be referred to as “detection target 72”.

  The specific object 71 is, for example, a road inclined with respect to the road where the vehicle 10 exists. As shown in FIG. 2C, when the vehicle 10 exists on a horizontal road, the road that is an uphill following the horizontal road corresponds to the specific object 71. Further, as shown in FIG. 2D, when the vehicle 10 exists on a downhill road, a horizontal road following the downhill road corresponds to the specific object 71. The magnitude of the inclination of the surface (here, the road surface) of the specific object 71 with respect to the road on which the vehicle 10 exists is, for example, greater than 0 degree and 30 degrees or less.

  The detection target 72 (see FIG. 2B) is, for example, an obstacle, and more specifically, a vehicle other than the vehicle 10, a wall, a fence, a pillar such as a power pole, and a car stop. An object that is not the specific object 71 and is not the detection target 72 is an object that is smaller in size than the detection target 72 and is, for example, an object (curbstone or the like) that forms a step with respect to the road.

  In FIG. 2C and FIG. 2D, the vehicle 10 exists near the boundary between a road that is a slope and a horizontal road. In these cases, the detection wave W1 (see FIG. 1) transmitted from each of the plurality of sensor units 20 is reflected on a road that is a hill or a horizontal road (specific object 71), and thus the reflected wave W2 is reflected. (See FIG. 1) occurs, and each of the plurality of sensor units 20 may receive the reflected wave W2. The sensor system 1 is configured to detect the specific object 71 in such a case and reduce the possibility of erroneously determining that the detection target 72 exists.

  As shown in FIG. 3A, the plurality of sensor units 20 are arranged in a line in the front portion of the vehicle 10. The plurality of sensor units 20 are attached to the bumper 11 (see FIG. 2A) of the vehicle 10. Although two sensor units 20 are illustrated in FIG. 3A, actually three or more sensor units 20 are provided side by side in one direction D <b> 1 of the vehicle 10. One direction D1 in which the plurality of sensor units 20 are arranged is a direction along the horizontal direction when the vehicle 10 is on a horizontal road, and is a direction orthogonal to the front-rear direction D2 of the vehicle 10. The front-rear direction D2 of the vehicle 10 is a direction along the straight traveling direction of the vehicle 10. The plurality of wave transmission units 21 (see FIG. 1) of the plurality of sensor units 20 are arranged in one direction D <b> 1 of the vehicle 10. Each sensor unit 20 transmits a detection wave W1 (see FIG. 1) from the wave transmission unit 21 and is reflected by the object 7 existing in the ellipsoidal area AR1 (see FIG. 1). Is received by the wave receiving unit 22 (see FIG. 1). The area AR1 is formed by the sensor unit 20 so as to extend from each sensor unit 20 in a direction along the front-rear direction D2 of the vehicle 10.

  The wave transmission part 21 (refer FIG. 1) of each sensor part 20 is the detection wave W1 (FIG. 1), the intensity is weak. Further, since the intensity of the detection wave W1 is attenuated as the detection wave W1 travels, the intensity of the detection wave W1 transmitted from the transmission unit 21 in each sensor unit 20 is weaker at a position farther from the sensor unit 20. Furthermore, the wave receiving unit 22 (see FIG. 1) of each sensor unit 20 receives the reflected wave W2 as the acute angle between the longitudinal direction D2 of the vehicle 10 and the traveling direction of the reflected wave W2 (see FIG. 1) increases. It has directivity with low sensitivity.

  The acquisition unit 4 includes, for example, an analog-digital conversion circuit, converts the received signal Sig1 acquired from the reception unit 22 from an analog signal to a digital signal, and outputs the converted signal to the determination unit 5. 4A and 4B respectively show the time variation of the received wave intensity I1 (voltage value) of the reflected wave W2 received by the receiving unit 22 of one sensor unit 20, and the received signal Sig1 acquired by the acquiring unit 4 It is a graph shown by this waveform. That is, FIGS. 4A and 4B each show the waveform of the reflected wave W2 held by the received signal Sig1. More specifically, FIGS. 4A and 4B respectively show the received intensity I1 of the reflected wave W2 generated from the detection wave W1 transmitted at one time among the detection waves W1 transmitted intermittently in each sensor unit 20. The time change of is shown.

  As shown in FIG. 1, in each of the plurality of sensor units 20, the wave transmission unit 21 transmits a detection wave W1. Thus, the sensor 2 transmits the plurality of detection waves W1 by transmitting the detection wave W1 from each of the plurality of transmission units 21 at least once. A plurality of reflected waves W2 generated by reflecting the plurality of detection waves W1 by the object 7 are received by the plurality of receiving units 22 and converted into a plurality of received signals Sig1. The sensor 2 further includes a control circuit 23 that controls the plurality of sensor units 20. The control circuit 23 shifts the phase of the detection wave W <b> 1 transmitted by each of the transmission units 21 of the plurality of sensor units 20 from each other and transmits the detection wave W <b> 1. Thereby, the detection wave W1 transmitted by the transmission unit 21 of some of the plurality of sensor units 20 and the detection wave W1 transmitted by the transmission unit 21 of another sensor unit 20 are mutually connected. The possibility of interference and the possibility that a plurality of reflected waves W2 interfere with each other are reduced.

  As illustrated in FIGS. 1 and 5, the acquisition unit 4 acquires a plurality of reception signals Sig1 output from the plurality of reception units 22 (acquisition step: step S1). The determination unit 5 determines the presence or absence of the detection target 72 based on the plurality of received signals Sig1 acquired by the acquisition unit 4 (determination step: steps S2 to S4). The output unit 6 outputs the determination result of the determination unit 5 (output step: step S5). The detection method according to the present embodiment includes the above-described acquisition step, determination step, and output step.

  More specifically, the output unit 6 outputs the determination result of the determination unit 5 to the vehicle control circuit 8 by a signal Sig2 (electric signal). The vehicle control circuit 8 is provided as a configuration outside the sensor system 1. Each of the sensor system 1 and the vehicle control circuit 8 is a partial configuration of an ECU (Electronic Control Unit) of the vehicle 10 (see FIG. 2A). The vehicle control circuit 8 controls at least one of the buzzer provided in the vehicle 10 and the brake of the vehicle 10 according to the determination result of the determination unit 5. For example, when the determination unit 5 determines that the detection target 72 exists, the vehicle control circuit 8 controls the buzzer provided in the vehicle 10 to sound a warning sound, thereby indicating the presence of the detection target 72 to the driver. To inform. In addition, the vehicle control circuit 8 may control the brake of the vehicle 10 to operate the brake instead of controlling the buzzer to sound the warning sound, or may control the buzzer to sound the warning sound. In addition to the above, the brake of the vehicle 10 may be controlled to operate the brake.

  More specifically, when the object 7 is the specific object 71, the determination unit 5 determines that the detection target 72 does not exist based on the plurality of received signals Sig1. Specifically, the determination unit 5 determines the presence / absence of the detection target 72 based on the waveforms of the plurality of reflected waves W2 indicated by the plurality of received signals Sig1 and the matching rates of the plurality of received signals Sig1. judge. To simplify the explanation, first, it is assumed that the plurality of received signals Sig1 always coincide with each other. Based on this assumption, the case where the determination unit 5 determines the presence / absence of the detection target 72 based on the waveforms of the plurality of reflected waves W2 indicated by the plurality of received signals Sig1 will be described. Here, the phases of the plurality of received signals Sig1 do not have to match.

  The determination unit 5 determines the presence / absence of the detection target 72 based on the waveforms of the plurality of reflected waves W2 indicated by the plurality of received signals Sig1. More specifically, the determination unit 5 determines the time point T3 (see FIG. 4A: time point T8 in FIG. 4B) when the received wave intensity I1 (see FIG. 4A) of each reflected wave W2 exceeds the first threshold value V1 (see FIG. 4A). ) And a time T4 (see FIG. 4A: time T9 in FIG. 4B) that exceeds the second threshold V2 (see FIG. 4A) (see FIG. 4A: time ΔT89 in FIG. 4B), The presence / absence of the detection target 72 is determined (step S2). Hereinafter, the time between the time when the received wave intensity I1 of the reflected wave W2 exceeds the first threshold value V1 and the time point when it exceeds the second threshold value V2 is also referred to as “difference time”. Specifically, when the difference time exceeds a predetermined time length, the determination unit 5 determines that the object 7 is not the detection target 72 but the specific object 71 and the detection target 72 does not exist (step S3). ). Further, when the difference time is equal to or shorter than the predetermined time length, the determination unit 5 determines that the object 7 is the detection target 72 and the detection target 72 exists (step S4). Moreover, the determination part 5 determines with the object 7 not existing, when the receiving intensity I1 of each reflected wave W2 does not exceed the 2nd threshold value V2 in step S1.

  The predetermined time length is, for example, a time length (about 174 μs) required for the detection wave W1 that is an ultrasonic wave to reciprocate a distance of 3 cm. The first threshold value V1 is smaller than the second threshold value V2. The first threshold value V1 is, for example, a voltage value that is approximately half of the second threshold value V2. The first threshold value V1 is determined in advance so that the first threshold value V1 is larger than the received wave intensity I1 of the reflected wave W2 that is generated when the detection wave W1 is reflected on a flat road that extends forward from the position where the vehicle 10 exists. It has been. The second threshold value V2 is a threshold value set for detecting the normal detection target 72. The second threshold value V2 is higher than the received wave intensity I1 in the wave receiving part 22 of the reflected wave W2 that is generated when the detection wave W1 is reflected by the detection target 72 existing in the area AR1 in front of the vehicle 10 (see FIG. 2B). The value is predetermined in advance. The first threshold value V1 and the second threshold value V2 are stored in a memory provided in the sensor system 1.

  As will be described later, when the reflected wave W2 generated by the detection wave W1 being reflected by the specific object 71 is received by the sensor unit 20, the difference time tends to exceed a predetermined time length. Moreover, when the reflected wave W2 generated by the detection wave 72 being reflected by the detection target 72 is received by the sensor unit 20, the difference time may be a predetermined time length or less. Therefore, the determination unit 5 can identify the specific object 71 and the detection target 72 based on the difference time.

  Further, the first threshold value V1 and the second threshold value V2 vary depending on the elapsed time from the time point T0 (time point T5 in FIG. 4B) when the transmission unit 21 starts transmitting the detection wave W1. As the elapsed time from the time point T0 (time point T5 in FIG. 4B) becomes longer, the reflected wave W2 from the object 7 farther from the sensor unit 20 is received by the wave receiving unit 22, and the received wave intensity I1 decreases. It is determined that the first threshold value V1 and the second threshold value V2 become smaller as the elapsed time becomes longer. More specifically, the first threshold value V1 and the second threshold value V2 are determined to decrease stepwise as the elapsed time becomes longer.

  In the following, the assumption that the plurality of received signals Sig1 always coincide with each other is removed. Then, the determination unit 5 determines whether or not the detection target 72 is present based on the waveforms of the plurality of reflected waves W2 indicated by the plurality of received signals Sig1 and the matching rates of the plurality of received signals Sig1. Will be described.

  For example, the determination unit 5 determines whether or not the matching rate of the plurality of received signals Sig1 is equal to or greater than a predetermined value according to the degree of matching of the waveforms of the plurality of received signals Sig1. More specifically, the determination unit 5 uses the waveform of one received signal Sig1 among the plurality of received signals Sig1 as a reference waveform, and compares the waveforms of the received signals Sig1 other than the received signal Sig1 with the reference waveform. . When the waveform of the received signal Sig1 other than the received signal Sig1 matches the reference waveform, the determining unit 5 determines that the match rate is equal to or greater than a predetermined value. It is determined that the value is less than the value. Matching the waveforms does not require that the phases match. In addition, not only when the waveforms match completely but also when the waveform difference is within a specified value.

  The determination unit 5 determines that the object 7 does not exist for any of the reception signals Sig1 when the reception intensity I1 of the reflected wave W2 indicated by the reception signal Sig1 does not exceed the second threshold value V2.

  In one or more received signals Sig1, the determination unit 5 has a received intensity I1 that exceeds the second threshold value V2, and the matching rate of the received signals Sig1 is less than a predetermined value. It is determined that the detection target 72 exists.

  On the other hand, in all the received signals Sig1 among the plurality of received signals Sig1, the determination unit 5 has a received signal intensity I1 that exceeds the second threshold value V2, and the coincidence rate of the received signals Sig1 is predetermined. If the value is greater than or equal to the value, the determination is further made according to the following conditions. First, when the difference time exceeds a predetermined time length in all the reception signals Sig1 among the plurality of reception signals Sig1, the determination unit 5 determines that the detection target 72 does not exist. Secondly, in the one or more received signals Sig1 among the plurality of received signals Sig1, when the difference time is equal to or shorter than a predetermined time length, the determination unit 5 determines that the detection target 72 exists.

  As will be described later, when the object 7 is a specific object 71 such as a slope, the matching rate of the plurality of received signals Sig1 tends to be equal to or higher than a predetermined value. Further, when the object 7 is the detection target 72 and is a wall (see FIG. 3B) inclined with respect to one direction D1 of the vehicle 10, the difference time in at least one received signal Sig1 is a predetermined time. May exceed length. On the other hand, in this case, the mutual coincidence rate of the plurality of received signals Sig1 tends to be less than a predetermined value.

  Therefore, the determination unit 5 can determine that the detection target 72 does not exist when the object 7 is a specific object 71 such as a slope. The determination unit 5 can determine that the detection target 72 exists when the object 7 is the detection target 72 and is a wall inclined with respect to the one direction D <b> 1 of the vehicle 10.

  4A and 4B, the transmission is finished from time T1 after a while after the transmission unit 21 starts transmitting the detection wave W1 at time T0 (time T6 after a while after time T5 in FIG. 4B). Until some time passes, reverberation occurs in the sensor unit 20. At this time, due to reverberation, the measured value of the received wave intensity I1 of the reflected wave W2 is larger than the actual intensity of the reflected wave W2. Therefore, the determination unit 5 receives the received signal intensity until the measured value of the received signal intensity I1 is less than the predetermined threshold value V3 (from time T1 to time T2 in FIG. 4A and from time T6 to time T7 in FIG. The measured value of I1 is handled as invalid data that is not used for determining whether the detection target 72 exists.

  The execution body of the detection system 3, the sensor system 1, and the detection method in the present disclosure includes a computer system. The computer system has one or more computers. The computer system mainly includes a processor and a memory as hardware. When the processor executes the program recorded in the memory of the computer system, a function as an execution subject of the detection system 3, the sensor system 1, and the detection method in the present disclosure is realized. The program may be recorded in advance in the memory of the computer system, but may be provided through an electric communication line, or a non-temporary program such as a memory card, optical disk, or hard disk drive (magnetic disk) that can be read by the computer system. And may be provided by being recorded on a typical recording medium. A processor of a computer system includes one or more electronic circuits including a semiconductor integrated circuit (IC) or a large scale integrated circuit (LSI). The plurality of electronic circuits may be integrated on one chip, or may be distributed on the plurality of chips. The plurality of chips may be integrated into one device, or may be distributed and provided in a plurality of devices.

(Operation example of sensor system)
As shown in FIG. 2A, when the object 7 does not exist in the area AR1, the received wave intensity I1 (see FIG. 4A) of the reflected wave W2 does not exceed the second threshold value V2 (see FIG. 4A). 5 determines that the object 7 does not exist. Further, even when an object having a size smaller than that of the detection target 72 exists in the area AR1, such as an object that forms a step with respect to the road, the received intensity I1 of the reflected wave W2 does not exceed the second threshold value V2. Accordingly, the determination unit 5 may determine that the object 7 does not exist.

  As shown in FIG. 2B, when a detection target 72 such as a wall along one direction D1 of the vehicle 10 is present in the area AR1, the received intensity I1 of the reflected wave W2 in each of the plurality of sensor units 20 is For example, the transition occurs as shown in FIG. 4A. In the vicinity of the time point T3, the wave receiving unit 22 receives the reflected wave W2 from the detection target 72, so that the received wave intensity I1 increases. At time T3, the received intensity I1 of the reflected wave W2 exceeds the first threshold V1, and at time T4, the received intensity I1 of the reflected wave W2 exceeds the second threshold V2, and a time ΔT34 (between time T3 and T4 ( The difference time is less than or equal to a predetermined time length. Therefore, the determination unit 5 determines that the detection target 72 exists.

  In FIG. 2C, the vehicle 10 exists on a horizontal road following the uphill road, and the uphill road corresponds to the specific object 71. In FIG. 2D, the vehicle 10 exists on a downhill road, and a horizontal road corresponds to the specific object 71. As shown in FIGS. 2C and 2D, when the specific object 71 exists in the area AR1, the received intensity I1 of the reflected wave W2 in each of the plurality of sensor units 20 changes as shown in FIG. 4B, for example. To do. In the vicinity of the time point T8, the reception unit 22 receives the reflected wave W2 from the specific object 71, and thus the reception intensity I1 increases. At time T8, the received intensity I1 of the reflected wave W2 exceeds the first threshold V1, and at time T9, the received intensity I1 of the reflected wave W2 exceeds the second threshold V2, and the time ΔT89 (between time T8 and T9) (Difference time) exceeds a predetermined time length. Therefore, the determination unit 5 determines that the detection target 72 does not exist.

  Here, in the case of FIG. 4B than in the case of FIG. 4A, the time T3 when the received intensity I1 exceeds the first threshold V1 (time T8 in FIG. 4B) and the time T4 when the second threshold V2 is exceeded. The time ΔT34 (time ΔT89 in FIG. 4B) between the time points (time T9 in FIG. 4B) is long. This is due to the following reason.

  FIG. 4B is an example of the transition of the received wave intensity I1 of the reflected wave W2 generated by the specific object 71 such as a slope. In the specific object 71, the surface of the specific object 71 that faces the vehicle 10 is inclined. Therefore, as shown in FIG. 2C, the specific object 71 is closer to the part 711 closer to the sensor unit 20 and farther from the sensor unit 20. There is a site 712. Then, the reflected wave W2 from the part 711 closer to the sensor part 20 is received first (at time T8) by the sensor part 20, and the reflected wave W2 from the part 712 farther from the sensor part 20 is later (at time T9). The sensor unit 20 receives the wave. A distance L1 between a straight line SL1 extending from the sensor unit 20 in the front-rear direction D2 of the vehicle 10 and the part 711 is longer than a distance L2 between the straight line SL1 and the part 712.

  As described above, the intensity of the detection wave W1 is weaker as the position is farther from the straight line SL1 extending from the sensor unit 20 in the front-rear direction D2 of the vehicle 10. Further, the intensity of the detection wave W <b> 1 is weaker as the position is farther from the sensor unit 20. Furthermore, the receiving sensitivity of the reflected wave W2 in the wave receiving unit 22 is smaller as the acute angle between the front-rear direction D2 of the vehicle 10 and the traveling direction of the reflected wave W2 is larger.

  Therefore, depending on the positional relationship among the sensor unit 20, the part 711, and the part 712, the received intensity I1 of the reflected wave W2 from the part 711 may be smaller than the received intensity I1 of the reflected wave W2 from the part 712. . Here, for example, the received intensity I1 of the reflected wave W2 from the part 711 is larger than the first threshold value V1 and smaller than the second threshold value V2. Further, the received intensity I1 of the reflected wave W2 from the part 712 is larger than the second threshold value V2. Therefore, when the reflected wave W2 from the specific object 71 is received by the sensor unit 20, the time T8 when the reflected wave W2 having the received wave intensity I1 larger than the first threshold value V1 is received (see FIG. 4B). And the time ΔT89 (see FIG. 4B) between the time point T9 (see FIG. 4B) when the reflected wave W2 having the received wave intensity I1 larger than the second threshold value V2 is received than the time ΔT34 in FIG. 4A. become longer.

  On the other hand, FIG. 4A is an example of transition of the received wave intensity I1 of the reflected wave W2 generated in the detection target 72 such as a wall along one direction D1 of the vehicle 10. In FIG. 4A, when the receiving unit 22 receives the reflected wave W2 near the time point T3, the received wave intensity I1 changes in a single pulse shape. In the detection target 72, the depth in the front-rear direction D <b> 2 of the vehicle 10 on the surface of the detection target 72 that faces the vehicle 10 is smaller than that of the specific object 71. Therefore, the received intensity I1 of the reflected wave W2 generated at the detection target 72 is substantially constant regardless of which part of the detection target 72 the detection wave W1 hits to generate the reflection wave W2. Therefore, the received wave intensity I1 in the vicinity of the time point T3 in FIG. 4A increases rapidly as compared with the received wave intensity I1 in the vicinity of the time point T8 in FIG. 4B. Thereby, the time ΔT34 is shorter than the time ΔT89.

  As described above, when the detection wave W1 is reflected by the specific object 71 (see FIG. 4B), the time ΔT89 of the time from when the received wave intensity I1 exceeds the first threshold value V1 to the second threshold value V2 is exceeded. However, it becomes longer than the time ΔT34 when the detection wave W1 is reflected by the detection target 72 such as a wall along one direction D1 of the vehicle 10 (see FIG. 4A). Therefore, the determination unit 5 can determine the presence / absence of the detection target 72 such as a wall along one direction D1 of the vehicle 10 based on the difference time (time ΔT34, ΔT89).

  3B, the object 7 is a wall inclined with respect to one direction D1 in which the plurality of sensor units 20 are arranged. In the description with reference to FIGS. 3A and 3B, a plurality (two in FIGS. 3A and 3B) of the sensor units 20 are also distinguished and referred to as sensor units 20a and 20b. When the object 7 is a wall inclined with respect to one direction D1 of the vehicle 10, the received wave intensity I1 of the reflected wave W2 at each sensor unit 20 is the same as when the object 7 is a specific object 71 such as a slope. May show temporal changes. More specifically, when the object 7 is a wall inclined with respect to the one direction D1 of the vehicle 10, the difference time may exceed a predetermined time length. This is because, when the object 7 is a wall inclined with respect to the one direction D1 of the vehicle 10, as in the case where the object 7 is the specific object 71 such as a slope, a part closer to the sensor unit 20a. This is because the reflected wave W2 from 713 is first received by the sensor unit 20a, and the reflected wave W2 from the part 714 farther from the sensor unit 20a is received by the sensor unit 20a later. Similarly, when the object 7 is a wall inclined with respect to the one direction D1 of the vehicle 10, the reflected wave W2 from the portion 715 closer to the sensor unit 20b of the object 7 is received by the sensor unit 20b first. The reflected wave W2 from the part 716 farther from the sensor unit 20b is received later by the sensor unit 20b.

  In FIG. 3A, in the front-rear direction D2 of the vehicle 10, the distance between the sensor unit 20a and the object 7 is substantially equal to the distance between the sensor unit 20b and the object 7. Therefore, the received signals Sig1 in the plurality of sensor units 20a and 20b substantially match except for the phase. More specifically, the received signals Sig1 in the plurality of sensor units 20a and 20b have substantially the same waveform when the phase of one received signal Sig1 is matched with the phase of the other received signal Sig1. The difference in phase of the received signals Sig1 in the plurality of sensor units 20a and 20b is caused by a phase shift that is intentionally provided in the detected wave W1 in order to reduce the possibility of interference between the detected waves W1 and reflected waves W2. to cause.

  In contrast, in FIG. 3B, the distance between the sensor unit 20 a and the object 7 is different from the distance between the sensor unit 20 b and the object 7 in the front-rear direction D <b> 2 of the vehicle 10. Therefore, the received signals Sig1 in the plurality of sensor units 20a and 20b have the same waveform even if the phase of one received signal Sig1 is matched with the phase of the other received signal Sig1 in addition to the phases not matching. do not do.

  As described above, the determination unit 5 determines that the detection target 72 exists when the coincidence rate of the plurality of received signals Sig1 is less than a predetermined value. Here, when the object 7 is a wall inclined with respect to one direction D1 of the vehicle 10, the coincidence rate of the plurality of received signals Sig1 becomes less than a predetermined value, and the determination unit 5 determines that the detection target 72 is It is determined that it exists. Further, as described above, the determination unit 5 determines that the detection target 72 does not exist when the object 7 is a road (such as a slope) inclined with respect to the road where the vehicle 10 exists. That is, the determination result of the determination unit 5 is different between the case where the object 7 is a wall inclined with respect to one direction D1 of the vehicle 10 and the case where the object 7 is a slope.

  Further, the detection target 72 and the specific object 71 exist around the vehicle 10, and among the plurality of sensor units 20, some of the sensor units 20 receive the reflected wave W2 from the detection target 72 and receive another sensor. The unit 20 may receive the reflected wave W2 from the specific object 71 in some cases. In this case, in the received signal Sig1 output from some of the plurality of sensor units 20, the difference time is equal to or less than a predetermined time length, and the received signal Sig1 output from another sensor unit 20 The difference time may exceed a predetermined time length. Then, since the coincidence rate of the plurality of received signals Sig1 is less than a predetermined value, the determination unit 5 determines that the detection target 72 exists.

(Effect of the sensor system of this embodiment)
In the sensor system 1 of the present embodiment, when the reflected wave W2 generated by the specific object 71 instead of the detection target 72 is received by the receiving unit 22, the determination unit 5 receives the received wave converted from the reflected wave W2. Based on the signal Sig1, it is determined that the detection target 72 does not exist. Thereby, in the sensor system 1, the performance which determines the presence or absence of the detection target 72 can be improved.

  Also, the determination unit 5 determines that the detection target 72 exists when the received wave intensity I1 of the reflected wave W2 exceeds a specified threshold value, and detects the detected object 72 when the received wave intensity I1 is equal to or less than the specified threshold value. Consider a case in which it is determined that does not exist. The prescribed threshold value may be a constant value, or may be a value that changes over time, like the first threshold value V1 and the second threshold value V2. In this case, in order to prevent the determination unit 5 from determining that the detection target 72 exists due to the reflected wave W2 generated by the specific object 71 such as a hill, reception of the reflected wave W2 generated by the specific object 71 such as the hill is received. The prescribed threshold value needs to be determined in advance so that the wave intensity I1 is less than or equal to the prescribed threshold value. However, the sensitivity with which the sensor system 1 detects the detection target 72 may decrease as the prescribed threshold value increases.

  On the other hand, in the sensor system 1 of the present embodiment, when the received intensity I1 of the reflected wave W2 exceeds the first threshold value V1 and the second threshold value V2, the determination unit 5 is based on the difference time, The presence / absence of the detection target 72 is determined. Therefore, even if the first threshold value V1 and the second threshold value V2 are determined in advance to a value smaller than the prescribed threshold value, the possibility that the sensitivity with which the sensor system 1 detects the detection target 72 is reduced can be reduced. .

(Modification of the embodiment)
In the embodiment, the determination unit 5 determines the presence / absence of the detection target 72 using the difference time obtained based on the received signal Sig1. On the other hand, the determination unit 5 may determine whether or not the detection target 72 exists based on the received signal Sig1 by another process. For example, the determination unit 5 determines the presence / absence of the detection target 72 according to the degree of matching between the waveform prepared in advance of the model of the reflected wave W2 and the waveform of the reflected wave W2 actually measured by the wave receiving unit 22. You may judge. Specifically, the determination unit 5 determines the value obtained by integrating the received wave intensity of the model of the reflected wave W2 over a certain period of time and the received wave intensity I1 of the reflected wave W2 actually measured by the wave receiving unit 22 over the certain period of time. The presence / absence of the detection target 72 may be determined according to the coincidence rate with the value integrated in step (b). Alternatively, the determination unit 5 responds according to the coincidence rate of the position and quantity of the local maximum point and the local minimum point of the waveform of the reflected wave W2 and the waveform of the reflected wave W2 actually measured by the receiving unit 22. Thus, the presence or absence of the detection target 72 may be determined.

  Further, in the embodiment, the determination unit 5 determines whether or not the matching rate of the plurality of received signals Sig1 is equal to or greater than a predetermined value according to the degree of matching of the waveforms of the received signals Sig1. judge. The determination unit 5 determines that the detection target 72 exists when the matching rate of the plurality of received signals Sig1 is less than a predetermined value. Here, the determination unit 5 may obtain the mutual coincidence rate of the plurality of received signals Sig1 by another process. For example, the determination unit 5 receives a plurality of reception ratios of the feature quantities of the waveform of each reflected wave W2, such as a value obtained by integrating the received intensity I1 of each reflected wave W2 indicated by each received signal Sig1 over a certain time. It may be regarded as the coincidence rate of the wave signals Sig1. Further, a configuration different from that of the determination unit 5 may obtain the matching rate of the plurality of received signals Sig1.

  The received signal Sig1 is not limited to a signal obtained by converting the reflected wave W2 into an electric signal, and may be any signal having information regarding the waveform of the reflected wave W2. For example, the received signal Sig1 may be a signal having information on when the received intensity I1 of the reflected wave W2 exceeds the first threshold value V1 and when the received signal intensity I1 exceeds the second threshold value V2. Alternatively, the received signal Sig1 may be a signal having information on the difference time in the reflected wave W2. Alternatively, the received signal Sig1 may be a signal having information on the characteristic amount of the waveform of the reflected wave W2, such as the position and quantity of the maximum point and the minimum point of the reflected wave W2.

  In addition, the plurality of sensor units 20 are not limited to being disposed in the front portion of the vehicle 10, and may be disposed in the rear portion, the right portion, and the left portion, for example.

  Further, the number of the sensor units 20 in the sensor 2 is not particularly limited, and may be one or plural.

  Further, the determination unit 5 may use another threshold value in addition to the first threshold value V1 and the second threshold value V2 in determining whether or not the detection target 72 is present. For example, it is detected that the time between the time point when the received wave intensity I1 exceeds the second threshold value V2 and the time point when the received signal intensity I1 exceeds the third threshold value that is larger than the second threshold value V2 exceeds a specified time length. You may add to the conditions determined by the determination part 5 that the object 72 does not exist.

  In the embodiment, the determination unit 5 identifies the specific object 71 and the detection target 72 and determines whether or not the detection target 72 exists, so that the sensor system 1 detects the detection target 72 and detects the specific object 71. It is configured not to. On the other hand, the determination unit 5 identifies the specific object 71 and the detection target 72 and determines whether or not both the specific object 71 and the detection target 72 exist, so that the sensor system 1 detects the specific object 71 and the detection target 72. You may be comprised so that both the object 72 may be detected.

  Further, it is not essential for the determination unit 5 to identify the specific object 71 and the detection target 72. The determination part 5 should just determine the presence or absence of the detection target 72 at least.

  In the embodiment, when the object 7 has a specific three-dimensional shape, the determination unit 5 determines that the detection target 72 does not exist based on one or a plurality of received signals Sig1. More specifically, the fact that the object 7 has a specific three-dimensional shape means that the surface of the object 7 has a specific inclination. Here, the fact that the object 7 has a specific three-dimensional shape is not limited to the exact matching of the shape of the object 7 and the specific three-dimensional shape, even if there is a certain degree of difference. Good. Similarly, the fact that the inclination of the surface of the object 7 is a specific inclination is not limited to exactly matching the inclination of the surface of the object 7 and the specific inclination, and there is a certain degree of difference. Also good.

  The specific three-dimensional shape is not limited to one three-dimensional shape, and may be a plurality of three-dimensional shapes. Then, when the object 7 has at least one of a plurality of three-dimensional shapes, the determination unit 5 may determine that the detection target 72 does not exist based on one or a plurality of received signals Sig1.

  In the sensor unit 20, the wave transmitting unit 21 and the wave receiving unit 22 may be provided in a single device, or may be provided separately in a plurality of devices. In the sensor 2, the plurality of sensor units 20 and the control circuit 23 may be provided in a single device, or may be provided separately in a plurality of devices.

(Summary)
As described above, the detection system 3 according to the present embodiment includes the acquisition unit 4, the determination unit 5, and the output unit 6. The acquisition unit 4 acquires one or a plurality of received signals Sig1. The one or more received signals Sig1 indicate information related to the waveform of the one or more reflected waves W2 that are generated when the transmitted one or more detected waves W1 are reflected by the object 7. The determination unit 5 determines the presence / absence of the detection target 72 based on one or a plurality of received signals Sig 1 acquired by the acquisition unit 4. The output unit 6 outputs the determination result of the determination unit 5. When the object 7 has a three-dimensional shape in which the surface of the object has a specific inclination, the determination unit 5 determines that the detection target 72 does not exist based on one or a plurality of received signals Sig1.

  According to the above configuration, the determination unit 5 determines that the detection target 72 does not exist when the object 7 has a three-dimensional shape in which the inclination of the surface of the object is a specific inclination. Thereby, compared with the case where the determination part 5 does not perform such a process, in the detection system 3, the performance which determines the presence or absence of the detection target 72 improves.

  In the detection system 3 according to the present embodiment, the one or more received signals Sig1 are preferably signals obtained by converting one or more reflected waves W2 into one or more electric signals.

  According to the above configuration, the received signal Sig1 can be easily generated from the reflected wave W2.

  In the detection system 3 according to the present embodiment, the determination unit 5 determines that the received intensity I1 of the reflected wave W2 is a plurality of threshold values (the first threshold value V1 and the second threshold value) in each of the one or more reflected waves W2. It is preferable to determine the presence / absence of the detection target 72 based on the time (time ΔT34 or ΔT89) between the respective time points (time points T3 and T4 or time points T8 and T9) exceeding the threshold value V2). The plurality of threshold values have individual values.

  According to the above configuration, the determination unit 5 performs a simple process of comparing the received wave intensity I1 of the reflected wave W2 with a plurality of threshold values (first threshold value V1 and second threshold value V2). Presence / absence can be determined.

  In the detection system 3 according to the present embodiment, the acquisition unit 4 acquires a plurality of received signals Sig1. The plurality of received signals Sig1 indicate information regarding the waveforms of the plurality of reflected waves W2 that are generated when the plurality of detected waves W1 are reflected by the object 7. The plurality of detection waves W1 are preferably transmitted from the plurality of transmission units 21 arranged in one direction D1. The determination unit 5 preferably determines the presence / absence of the detection target 72 based on the matching rate of the plurality of received signals Sig1.

  According to said structure, the determination part 5 can determine the presence or absence of the detection target 72 with sufficient precision by the determination based on the mutual coincidence of the plurality of received signals Sig1.

  In addition, the sensor system 1 according to this embodiment includes a detection system 3 and a sensor 2. The sensor 2 transmits one or a plurality of detection waves W1, converts the one or a plurality of reflected waves W2 into one or a plurality of received signals Sig1, and outputs them to the acquisition unit 4.

  According to the above configuration, the determination unit 5 of the detection system 3 determines that the detection target 72 does not exist when the object 7 has a three-dimensional shape in which the inclination of the surface of the object is a specific inclination. Thereby, compared with the case where the determination part 5 does not perform such a process, in the sensor system 1, the performance which determines the presence or absence of the detection target 72 improves.

  Moreover, the detection method according to the present embodiment includes an acquisition step, a determination step, and an output step. In the acquisition step, one or a plurality of received signals Sig1 are acquired. The one or more received signals Sig1 indicate information related to the waveform of the one or more reflected waves W2 that are generated when the transmitted one or more detected waves W1 are reflected by the object 7. In the determination step, the presence / absence of the detection target 72 is determined based on one or a plurality of received signals Sig1 acquired in the acquisition step. In the output step, the determination result in the determination step is output. In the determination step, when the object 7 has a three-dimensional shape with a specific inclination of the surface of the object, it is determined that the detection target 72 does not exist based on one or a plurality of received signals Sig1.

  According to the above configuration, in the determination step, it is determined that the detection target 72 does not exist when the object 7 has a three-dimensional shape in which the surface inclination of the object is a specific inclination. Thereby, the performance which determines the presence or absence of the detection target 72 improves compared with the case where such a process is not performed in a determination step.

DESCRIPTION OF SYMBOLS 1 Sensor system 2 Sensor 21 Transmission part 3 Detection system 4 Acquisition part 5 Determination part 6 Output part 7 Object 72 Detection target D1 One direction I1 Received intensity Sig1 Received signal T3, T4, T8, T9 Time point ΔT34, ΔT89 Time V1 first threshold (threshold)
V2 Second threshold (threshold)
W1 Detection wave W2 Reflection wave

Claims (6)

An acquisition unit for acquiring one or a plurality of received signals indicating information on a waveform of one or a plurality of reflected waves generated by reflecting one or a plurality of detected waves transmitted by an object;
A determination unit that determines presence or absence of a detection target based on the one or more received signals acquired in the acquisition unit;
An output unit that outputs a determination result of the determination unit,
The determination unit determines that the detection target does not exist based on the one or the plurality of received signals when the object has a three-dimensional shape with a specific inclination of the surface of the object.
Detection system. The one or more received signals are signals obtained by converting the one or more reflected waves into one or more electrical signals.
The detection system according to claim 1. In each of the one or more reflected waves, the determination unit determines whether the detection target exists based on the time between each time point when the received wave intensity of the reflected wave exceeds a plurality of threshold values having individual values Determine
The detection system according to claim 1 or 2. The acquisition unit is configured to receive the plurality of reception waves indicating information on waveforms of the plurality of reflected waves generated by the plurality of detection waves transmitted from the plurality of transmission units arranged in one direction being reflected by the object. Get the signal,
The determination unit determines the presence / absence of the detection target based on the matching rate of the plurality of received signals.
The detection system as described in any one of Claims 1-3. The detection system according to any one of claims 1 to 4,
A sensor that transmits the one or more detection waves, converts the one or more reflected waves into the one or more received signals, and outputs the signals to the acquisition unit,
Sensor system. An acquisition step of acquiring one or a plurality of received signals indicating information on a waveform of one or a plurality of reflected waves generated by reflecting one or a plurality of detected waves transmitted by an object;
A determination step of determining the presence or absence of a detection target based on the one or more received signals acquired in the acquisition step;
An output step for outputting a determination result in the determination step,
In the determination step, when the object has a three-dimensional shape with a specific inclination of the surface of the object, it is determined that the detection target does not exist based on the one or the plurality of received signals.
Detection method.

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