Distance measuring device, distance measuring method, program, and distance measuring system

Abstract

To provide a distance measuring device, a distance measuring method and a program that can suppress real time loss associated with an information amount of waveform information which a wave reception signal has, and data transmission.SOLUTION: A distance measuring device comprises: a plurality of transducers; a transmission circuit; a reception circuit; a transfer data generation circuit; and a transfer circuit. The transmission circuit transmits a transmission wave from at least one transducer of a plurality of transducers. The reception circuit outputs a reception signal digitizing a reflection wave of the transmission wave received by each of the plurality of transducers using a sampling frequency being more than or equal to a frequency of the transmission wave. The transfer data generation circuit divides the reception signal in a time sequence output by the reception circuit into a target period in which wave height is more than or equal to a threshold value and a non-target period in which the wave height is less than the threshold value, performs thinning-out processing for the reception signal of other period other than the non-target period, and generates waveform information indicating a waveform received by the transducer. The transfer circuit outputs waveform information generated by the transfer data generation circuit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a distance measuring device and a distance measuring method. 、 program and ranging system Regarding. [Background technology]

[0002] Conventionally, there is known a technology that uses a transducer such as an ultrasonic sensor mounted on a vehicle to detect objects such as obstacles, preceding vehicles, pedestrians, etc. Also, there is known a technology that performs various vehicle controls to improve the traveling safety of the vehicle, such as activating automatic brakes and notifying the driver, based on the object detection results by the transducer.

[0003] In addition, as a method of object detection, a transducer receives waves reflected from an obstacle, converts the received signal corresponding to the reflected waves into a received waveform, and then performs a threshold judgment.The transducer calculates the distance to the obstacle from the time when the signal exceeds the threshold, and outputs the calculated distance to a control device that controls the transducer (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-057340 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned conventional technology, threshold judgment is performed on the received signal, which impairs waveform information such as the amplitude and phase of the received signal. As a result, the information on obstacles detected by the transducer is partially missing. Furthermore, the amount of waveform information contained in the received signal is too large to be transmitted to the control device that controls the transducer, and the communication speed between the transducer and the control device is insufficient, impairing real-time performance. Therefore, there is room for further improvement in order to detect more obstacle information with the transducer.

[0006] The present disclosure provides a distance measuring device and a distance measuring method that can reduce the amount of waveform information contained in a received signal and the loss of real-time performance associated with data transmission. 、 program and ranging system to provide. [Means for solving the problem]

[0007] A distance measuring device according to the present disclosure includes: Transmitter / Receiver The distance measuring device includes a transmitting circuit, a receiving circuit, a transfer data generating circuit, and a transfer circuit. The transducer The receiving circuit transmits the transmitted wave from The transducer The transducer outputs a received signal by digitizing a reflected wave of the transmitted wave received by the transducer using a sampling frequency equal to or higher than the frequency of the transmitted wave. The transfer data generation circuit divides the time-series received signal output by the receiving circuit into a target period in which the wave height is equal to or higher than a threshold and a non-target period in which the wave height is less than the threshold, performs thinning processing on the received signal in periods other than the non-target period, and generates waveform information indicating the waveform received by the transducer. The transfer circuit outputs the waveform information generated by the transfer data generation circuit. [Effects of the Invention]

[0008] According to the distance measuring device of the present disclosure, it is possible to reduce the amount of waveform information contained in the received signal and the loss of real-time performance related to data transmission. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a distance measuring system according to the first embodiment. [Figure 2] FIG. 2 is a graph showing an example of waveform information generated by the distance measuring device according to the first embodiment. [Figure 3] FIG. 3 is a diagram illustrating an example of the hardware configuration of the distance measuring device according to the first embodiment. [Figure 4] FIG. 4 is a flowchart showing an example of the operation of the distance measuring device according to the first embodiment. [Figure 5] FIG. 5 is a block diagram showing an example of the configuration of a distance measuring system according to a comparative example. [Figure 6] FIG. 6 is a block diagram showing an example of the configuration of a distance measuring system according to a comparative example. [Figure 7] FIG. 7 is a block diagram showing an example of the configuration of a distance measuring system according to the second embodiment. [Figure 8] FIG. 8 is a graph showing an example of waveform information generated by the distance measuring device according to the second embodiment. [Figure 9] FIG. 9 is a flowchart showing an example of the operation of the distance measuring device according to the second embodiment. [Figure 10] FIG. 10 is a block diagram showing an example of the configuration of a distance measuring system according to the third embodiment. [Figure 11] FIG. 11 is a graph showing an example of waveform information transferred by the distance measuring device according to the third embodiment. [Figure 12] FIG. 12 is a flowchart showing an example of the operation of the distance measuring device according to the third embodiment. [Figure 13] FIG. 13 is a graph showing an example of waveform information generated by the distance measuring device according to the first modification. [Figure 14] FIG. 14 is a flowchart showing an example of the operation of the distance measuring device according to the first modification. [Figure 15] FIG. 15 is a graph showing an example of waveform information generated by the distance measuring device according to the second modification. [Figure 16] FIG. 16 is a graph showing an example of waveform information generated by the distance measuring device according to the second modification. [Figure 17] FIG. 17 is a flowchart showing an example of the operation of the distance measuring device according to the second modification. [Figure 18] FIG. 18 is a flowchart showing an example of the operation of the distance measuring device according to the second modification. [Figure 19] FIG. 19 is a graph showing an example of waveform information generated by a distance measuring device according to the combination. [Figure 20] FIG. 20 is a graph showing an example of waveform information generated by a distance measuring device according to the combination. [Figure 21] FIG. 21 is a graph showing an example of waveform information generated by a distance measuring device according to the combination. [Figure 22] FIG. 22 is a graph showing an example of waveform information generated by a distance measuring device according to the combination. [Figure 23] FIG. 23 is a graph showing an example of waveform information generated by a distance measuring device according to the combination. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of a distance measuring device according to the present disclosure will be described with reference to the drawings.

[0011] (First embodiment) FIG. 1 shows the configuration of a ranging system according to the first embodiment. The ranging system 100 is mounted on, for example, a vehicle (not shown). As shown in FIG. 1, the ranging system 100 includes a ranging control device 10, a ranging device 20, and a vehicle control device 30. The ranging system 100 may also include other devices. Although the ranging control device 10, the ranging device 20, and the vehicle control device 30 are shown in FIG. 1 as separate devices, some or all of these devices may be integrated. The ranging system 100 may also include multiple ranging devices 20.

[0012] The distance measurement control device 10 is a device that controls the distance measurement device 20. The distance measurement control device 10 also detects objects present around the vehicle based on waveform information acquired from the distance measurement device 20. The distance measurement control device 10 includes a sweep control circuit 11, an acquisition circuit 12, an object detection circuit 13, a coordinate calculation circuit 14, and a collision determination circuit 15.

[0013] The sweep control circuit 11 performs sweep control so that ultrasonic waves (hereinafter also referred to as transmission waves) are transmitted to the distance measuring device 20. Specifically, the sweep control circuit 11 performs sweep control so that transmission waves are transmitted to the distance measuring device 20 in order to detect an object that is present around the vehicle.

[0014] In this embodiment, the terms "object" and "obstacle" include pedestrians and other vehicles. Also, objects that do not hinder the vehicle's travel, such as unevenness in the road surface, are not included in the term "obstacle."

[0015] The acquisition circuit 12 acquires waveform information. Specifically, the acquisition circuit 12 acquires waveform information output by the distance measuring device 20.

[0016] The object detection circuit 13 detects objects present around the vehicle from the waveform information. Specifically, the object detection circuit 13 detects objects present around the vehicle based on the time from when one distance measuring device 20 transmits a transmission wave until when multiple distance measuring devices 20 receive the reflected wave that is reflected back from an obstacle present around the vehicle, which is included in the waveform information acquired by the acquisition circuit 12. The waveform information will be described in detail later.

[0017] The coordinate calculation circuit 14 calculates the coordinates of an object from the object detected by the object detection circuit 13. Specifically, the coordinate calculation circuit 14 calculates the coordinates of an object present around the vehicle (hereinafter also referred to as a detection point) based on the time, contained in the waveform information acquired by the acquisition circuit 12, from when one distance measuring device 20 transmits a transmission wave to when multiple distance measuring devices 20 receive the reflected wave that is reflected back by an obstacle present around the vehicle.

[0018] The collision determination circuit 15 determines the possibility of a collision between the vehicle and an obstacle corresponding to the detection point. Specifically, when the detection point detected by the coordinate calculation circuit 14 intersects with the vehicle, the collision determination circuit 15 determines whether or not there is a possibility of a collision between the vehicle and the obstacle corresponding to the detection point.

[0019] The distance measuring device 20 includes an analog control circuit 21, a transmission circuit 22, a piezoelectric element 23, a reception circuit 24, a transfer data generation circuit 26, a transfer buffer 27, and a transfer circuit 28. In this embodiment, a plurality of distance measuring devices 20 are provided on a vehicle. The distance measuring devices 20 are arranged in positions on the vehicle that are advantageous for detecting or measuring the distance to surrounding objects. For example, a plurality of distance measuring devices 20 are arranged at a distance on the bumpers at the front and rear ends of the vehicle to detect objects in front of and behind the vehicle.

[0020] The distance measuring device 20 transmits a transmission wave based on the sweep control performed by the distance measurement control device 10. The distance measuring device 20 is, for example, a sonar.

[0021] The analog control circuit 21 controls the transmission circuit 22 based on the processing controlled by the scanning control circuit 11. Specifically, as the processing controlled by the scanning control circuit 11, the analog control circuit 21 controls the transmission circuit 22 so that the transmission circuit 22 applies an AC voltage to the piezoelectric element 23. The AC voltage applied by the transmission circuit 22 to the piezoelectric element 23 is, for example, 40 kHz to 75 kHz.

[0022] The transmission circuit 22 operates based on processing controlled by the analog control circuit 21. For example, the transmission circuit 22 applies a pulsed AC voltage to the piezoelectric element .

[0023] The piezoelectric element 23 deforms in response to the applied voltage and transmits ultrasonic waves (hereinafter also referred to as transmission waves) of approximately the same frequency. Specifically, when the transmission circuit 22 operates, an AC voltage is applied to the piezoelectric element 23, which deforms in response to the AC voltage and transmits ultrasonic waves of the same frequency. The transmitted ultrasonic waves are pulsed. When the pulsed ultrasonic waves hit the road surface or an obstacle, they are reflected, and a portion of them returns to the distance measuring device 20. The piezoelectric element 23 then converts the sound pressure applied to the surface of the returned reflected wave into a voltage, and outputs a voltage proportional to the sound pressure of the received sound to the reception circuit 24. The piezoelectric element 23 is an example of a transducer.

[0024] The receiving circuit 24 acquires the voltage output by the piezoelectric element 23. The receiving circuit 24 also performs digital conversion on the acquired voltage output by the piezoelectric element 23 using a sampling frequency that is approximately twice the frequency of the transmitted ultrasonic waves.

[0025] In this embodiment, as described above, the AC voltage applied by the transmission circuit 22 to the piezoelectric element 23 is, for example, 40 kHz to 75 kHz, so the sampling frequency of the reception circuit 24 may be more than twice the frequency of the transmitted ultrasonic waves, 80 kHz to 150 kHz or more, for example, 1.25 MHz. Furthermore, the reception circuit 24 performs analog-to-digital conversion on the voltage output by the piezoelectric element 23 to generate a reception signal (hereinafter also referred to as an AD value), and outputs the reception signal to the transfer data generation circuit 26.

[0026] The determination circuit 25 performs threshold determination on the received signal. Specifically, the determination circuit 25 performs threshold determination on the AD value output by the receiving circuit 24. The AD value obtained by analog-to-digital conversion by the receiving circuit 24 may contain noise (thermal noise, for example). The determination circuit 25 sets a threshold α to remove noise, and performs threshold determination on the AD value output by the receiving circuit 24.

[0027] The transfer data generation circuit 26 acquires the AD values output by the receiving circuit 24. The transfer data generation circuit 26 also identifies a target period in which the wave height is equal to or greater than a threshold from the time-series received signal output by the receiving circuit, divides the period into a target period in which the wave height is equal to or greater than the threshold and a non-target period in which the wave height is less than the threshold, executes processing (thinning processing) to thin out the received signal in periods other than the non-target period (non-target period), and generates waveform information indicating the waveform received by the transducer.

[0028] Here, the waveform information indicates the relationship between the AD value output by the receiving circuit 24 and time. Specifically, when the determination circuit 25 compares the AD value with a threshold and determines that the AD value is equal to or greater than the threshold, the transfer data generation circuit 26 identifies, from the time-series received signal output by the receiving circuit, a period in which the wave height is equal to or greater than the threshold, as well as predetermined periods located before and after the period, as the target period. The waveform information includes one or more of the start time of the target period, the end time of the target period, and the sample period of the target period.

[0029] The thinning process performed by the transfer data generation circuit 26 will now be described with reference to Fig. 2. Fig. 2 is a graph showing waveform information generated by the transfer data generation circuit 26. The horizontal axis represents time, and the vertical axis represents the AD value. α is the threshold value used by the determination circuit 25 to perform threshold determination.

[0030] The transfer data generating circuit 26 determines that the AD value is equal to or greater than the threshold value α by comparing the AD value with the threshold value α. pulse During this period, the transfer data generating circuit 26 generates waveform information based on the AD value output by the receiving circuit 24. Thereafter, the transfer data generating circuit 26 outputs the generated waveform information to the transfer buffer 27.

[0031] Graph G1 shown in Fig. 2 is the reverberation of the piezoelectric element 23. The piezoelectric element 23 continues to vibrate even after transmission (for example, application of AC voltage) has stopped. This vibration after application of AC voltage has stopped is shown as graph G1. Graph G2 shown in Fig. 2 is the reflected wave that has been reflected back by an object present around the vehicle.

[0032] Further, the transfer data generating circuit 26 pulse The time T before the end of buf During this time, the decision circuit 25 compares the AD value with the threshold value, and if the AD value is equal to or greater than the threshold value, the T buf The AD value may be generated as waveform information during a predetermined time T pulse After that, press T again. buf The transfer data generating circuit 26 may generate an AD value as waveform information during T bufDuring this time, if the AD value is less than the threshold, waveform information does not need to be generated.

[0033] Furthermore, the transfer data generation circuit 26 may generate the AD value output by the receiving circuit 24 as waveform information when the judgment circuit 25 compares the AD value with a threshold value and the AD value is equal to or greater than the threshold value, and may continue to generate waveform information until the AD value becomes less than the threshold value.

[0034] In addition, the transfer data generating circuit 26 detects a predetermined time T before the AD value becomes equal to or greater than the threshold value. pre The AD values included in pulse During this time, the AD value output by the receiving circuit 24 is generated as waveform information. pulse Since waveform information of AD values below the threshold value following AD values above the threshold value can be generated, the waveform received by the transducer can be accurately obtained.

[0035] Furthermore, the transfer data generation circuit 26 acquires a TOF (Time of Flight) that indicates a measurement value of the time from when the piezoelectric element 23 transmits the signal until when the received wave reflected by the target is received. Specifically, the transfer data generation circuit 26 acquires the start time T1 and stop time T2 of the AD value together with the generated waveform information, and outputs these to the transfer buffer 27. Note that the transfer data generation circuit 26 may sequentially output the generated waveform information to the transfer buffer 27.

[0036] The transfer data generation circuit 26 generates waveform information from the reverberation of the piezoelectric element 23 and the reflected waves that are reflected by objects around the vehicle. The transfer data generation circuit 26 does not need to generate waveform information for AD values that are less than the threshold value α.

[0037] For example, the transfer data generation circuit 26 does not generate waveform information that includes unnecessary information such as noise, and the distance measurement control device 10 specifies a target period to detect objects present around the vehicle and generates the waveform information. Also, because the transfer data generation circuit 26 specifies a target period and does not output unnecessary information, the transmission time can be reduced.

[0038] The transfer buffer 27 stores the waveform information output by the transfer data generation circuit 26. The transfer circuit 28 transfers the waveform information generated by the transfer data generation circuit 26. Specifically, the transfer circuit 28 outputs the waveform information stored in the transfer buffer 27 to the distance measurement control device 10.

[0039] The vehicle control device 30 is a device that controls various behaviors of the vehicle. For example, when the collision determination circuit 15 determines that there is a possibility of a collision between the vehicle and an obstacle corresponding to a detection point, the vehicle control device 30 warns the user of the possibility of a collision with the obstacle. Note that the functions of the vehicle control device 30 are not limited to this.

[0040] Next, we will explain the hardware configuration of the distance measuring device 20. As shown in Fig. 3, the distance measuring device 20 has a CPU (Central Processing Unit) 201, a ROM (Read Only Memory) 202, a RAM (Random Access Memory) 203, an I / F (Interface) 204, a flash memory 205, etc., which are interconnected via a bus 206, and has a hardware configuration using a normal computer.

[0041] The CPU 201 is a calculation device that controls the entire distance measuring device 20. The CPU 201 is an example of a processor, and another processor or processing circuit may be provided instead of the CPU 201. The ROM 202 stores programs and the like that realize various processes by the CPU 201. The RAM 203 is, for example, a main storage device of the distance measuring device 20, and stores data used in various processes by the CPU 201.

[0042] The I / F 204 is an interface for transmitting and receiving data to and from the ranging control device 10, and is, for example, a CAN (Controller Area Network). The I / F 204 may also transmit and receive information to and from other devices installed in the vehicle via a CAN or the like within the vehicle. The flash memory 205 is an example of a writable non-volatile storage medium. The ROM 202, RAM 203, and flash memory 205 are also referred to as memory circuits. The ranging device 20 may include another storage device, such as an HDD (Hard Disk Drive), instead of or in addition to the flash memory 205.

[0043] Furthermore, the hardware configuration of each of the distance measurement control device 10 and the vehicle control device 30 includes, for example, a processing circuit such as a CPU, a ROM, a RAM, an I / F, a flash memory, and the like.

[0044] Next, a description will be given of the operation executed by the distance measuring device 20 configured as above. In Fig. 4, a case will be described in which the receiving circuit 24 performs analog-to-digital conversion on the voltage output by the piezoelectric element 23 and outputs the AD value to the transfer data generating circuit 26.

[0045] The transfer data generation circuit 26 acquires the AD value output by the receiving circuit 24 (step S1). Subsequently, the determination circuit 25 determines whether the AD value is equal to or greater than the threshold value α (step S2). Here, if the determination circuit 25 determines that the AD value is less than the threshold value α (step S2: No), this process ends. On the other hand, if the determination circuit 25 determines that the AD value is equal to or greater than the threshold value α (step S2: Yes), the process proceeds to step S3.

[0046] When the determination circuit 25 determines that the AD value is equal to or greater than the threshold value α, the transfer data generation circuit 26 generates waveform information for the AD value output by the receiving circuit 24 (step S3). The transfer data generation circuit 26 outputs the generated waveform information to the transfer buffer 27.

[0047] Next, the determination circuit 25 determines whether thepulse The time T before buf During this time, it is determined whether the AD value is equal to or greater than the threshold value α (step S4). If the determination circuit 25 determines that the AD value is not equal to or greater than the threshold value α (step S4: No), the process proceeds to step S6. On the other hand, if the determination circuit 25 determines that the AD value is equal to or greater than the threshold value α (step S4: Yes), the process proceeds to step S5.

[0048] The transfer data generation circuit 26 determines whether the predetermined time T pulse The time T before buf If it is determined that the AD value is equal to or greater than the threshold value α during this period, the transfer data generation circuit 26 generates waveform information for the AD value output by the receiving circuit 24 (step S5). The transfer data generation circuit 26 outputs the generated waveform information to the transfer buffer 27.

[0049] Next, the transfer data generating circuit 26 detects a predetermined time T before the AD value becomes equal to or greater than the threshold value. pre The AD value included in the waveform information is generated as waveform information (step S6). The transfer data generation circuit 26 outputs the generated waveform information to the transfer buffer 27. Note that step S6 may be omitted.

[0050] Next, the transfer data generation circuit 26 acquires a TOF indicating a measurement value of the time from when the piezoelectric element 23 transmits to when the received wave reflected by the target is received (step S7). The transfer data generation circuit 26 outputs the acquired TOF to the transfer buffer 27. When step S7 ends, this process ends.

[0051] Next, the effects of the distance measuring system 100 according to the first embodiment will be described using a comparative example. A distance measuring system 200 shown in FIG.

[0052] The distance measurement control device 40 includes a scanning control circuit 41, a receiving circuit 42, an object detection circuit 43, a coordinate calculation circuit 44, and a collision determination circuit 45.

[0053] The sweep control circuit 41 controls the sweep so that the distance measuring device 50 transmits ultrasonic waves. The receiving circuit 42 acquires the voltage output by the piezoelectric element 52. The object detection circuit 43 detects objects present around the vehicle from the voltage. The coordinate calculation circuit 44 calculates the coordinates of the object detected by the object detection circuit 43. The collision determination circuit 45 determines the possibility of a collision between the vehicle and an obstacle corresponding to the detection point.

[0054] The distance measuring device 50 includes a transmission circuit 51 and a piezoelectric element 52. The transmission circuit 51 applies an AC voltage to the piezoelectric element 53. The piezoelectric element 53 deforms in response to the AC voltage and transmits ultrasonic waves of approximately the same frequency.

[0055] The distance measurement system 200 of the comparative example is susceptible to noise because it outputs the voltage (analog signal) output by the piezoelectric element 23 of the distance measurement device 50 to the distance measurement control device 40. This is because the voltage output to the distance measurement control device 40 is a weak analog signal of about several mV, and has low noise resistance.

[0056] This weak analog signal is transmitted over a long distance, for example, from sonars installed at the front and rear of the vehicle via lines from the distance measuring device 50 to the distance measuring control device 40, and various electromagnetic noises superimposed during this process may be mistaken for an obstacle detection signal. Also, for the distance measuring control device 40 to control multiple distance measuring devices 50, a P2P (Peer to Peer) connection is required, which can make the harness connection complicated.

[0057] On the other hand, in the distance measuring system 100 of this embodiment, inside the distance measuring device 20, the receiving circuit 24 acquires the voltage output by the piezoelectric element 23 and performs analog-to-digital conversion of the acquired voltage output by the piezoelectric element 23 at a frequency that is more than twice the frequency of the transmitted ultrasonic waves. Therefore, compared to the distance measuring system 200 of the comparative example, the distance measuring system 100 has high noise resistance. Furthermore, since the distance measuring system 100 uses a communication method that uses CAN for the I / F 204, it can be connected with fewer harnesses.

[0058] 6 includes a distance measurement control device 60 and a distance measurement device 70. The distance measurement control device 60 includes a scanning control circuit 61, a coordinate calculation circuit 62, and a collision determination circuit 63.

[0059] The sweep control circuit 61 controls sweeping so as to transmit ultrasonic waves to the distance measuring device 70. The coordinate calculation circuit 62 calculates the coordinates of an object from the object detected by the object detection circuit 75. The collision determination circuit 63 determines whether the detection point intersects with the vehicle and whether there is a possibility of a collision between the vehicle and the obstacle corresponding to the detection point.

[0060] The distance measuring device 70 includes an analog control circuit 71 , a transmitting circuit 72 , a piezoelectric element 73 , a receiving circuit 74 , and an object detecting circuit 75 .

[0061] The analog control circuit 71 controls the transmission circuit 72 based on the processing controlled by the scanning control circuit 61. The transmission circuit 72 operates based on the processing controlled by the analog control circuit 71. The piezoelectric element 73 deforms in response to the AC voltage and transmits ultrasonic waves of approximately the same frequency.

[0062] The receiving circuit 74 acquires the voltage output by the piezoelectric element 73, performs analog-to-digital conversion, and generates an AD value. The receiving circuit 74 also generates and outputs waveform information based on the results of further enveloping the analog-to-digital converted AD value. The waveform information generated by the receiving circuit 74 includes a time of flight (TOF) and a peak value. The object detection circuit 75 detects objects present around the vehicle from the waveform information output by the receiving circuit 74.

[0063] In the distance measurement system 300 of the comparative example, the distance measurement device 70 detects an object from waveform information including TOF and peak value, and outputs the result to the distance measurement control device 60. Therefore, the result of detecting the object is transmitted to the distance measurement control device 60. Furthermore, if the AD value converted from analog to digital by the receiving circuit 74 is output as is to the distance measurement control device 60, the transmitted AD value will be enormous because it has not been carefully examined. For example, if multiple distance measurement devices 70 are connected to the distance measurement control device 60 via a bus, the amount of information will be enormous, increasing the communication volume and making it difficult to output in real time.

[0064] On the other hand, in the ranging system 100 of this embodiment, when the determination circuit 25 compares the AD value with a threshold and determines that the AD value is equal to or greater than the threshold, the transfer data generation circuit 26 identifies, from the time-series received signal output by the receiving circuit, a period in which the wave height is equal to or greater than the threshold and a predetermined period before and after that period as a target period.The transfer data generation circuit 26 then executes processing to thin out the received signal for periods other than the target period, and generates waveform information indicating the waveform received by the transducer.As a result, compared to the ranging system 300 of the comparative example, the ranging system 100 of this embodiment can reduce the amount of waveform information contained in the received signal and the loss of real-time data transmission.

[0065] (Second embodiment) The second embodiment will be described with reference to the drawings. Explanations of parts common to the first embodiment will be omitted where appropriate. Note that components similar to those in the first embodiment will be given the same reference numerals and explanations will be omitted where appropriate.

[0066] In the first embodiment described above, the transfer data generation circuit 26 generates waveform information based on the result of the determination made by the determination circuit 25. In the second embodiment, the transfer data generation circuit 26a corresponding to the transfer data generation circuit 26 generates waveform information based on the time when the transducer transmits the transmission wave.

[0067] Specifically, as shown in FIG. 7, the distance measuring device 20a according to the second embodiment further includes a timing circuit 29. The timing circuit 29 measures the time acquired when at least one transducer transmits a transmission wave. Specifically, the timing circuit 29 acquires the time when the piezoelectric element 23 transmits the transmission wave. The timing circuit 29 measures the time, taking the time when the piezoelectric element 23 transmits the transmission wave as 0. The timing circuit 29 outputs the measured time to the transfer data generation circuit 26.

[0068] The transfer data generation circuit 26a measures the time elapsed since the transmission of the transmission wave based on the time measured by the timing circuit 29, and specifies the target period as the period from the start of this measurement to the end of the reverberation generated in the transducer that transmitted the transmission wave.The transfer data generation circuit 26a then generates waveform information for the reception signal output by the reception circuit 24.In other words, the transfer data generation circuit 26a measures the time elapsed since the transmission of the transmission wave, and changes the generation process of the waveform information according to the measured value.

[0069] The processing performed by the transfer data generation circuit 26a will now be described with reference to Fig. 8. Fig. 8 is a graph showing waveform information generated by the transfer data generation circuit 26a. The horizontal axis represents time, and the vertical axis represents the AD value.

[0070] Specifically, the transfer data generating circuit 26a receives the data when the timer circuit 29 reaches a predetermined time T near When the time is measured, the number of bits of the AD value output by the receiving circuit 24 is reduced and waveform information is generated. In this process, when the transmission wave transmitted by the piezoelectric element 23 is far away, the wave height is small and the number of bits is reduced in order to reduce the waveform information generated by the transfer data generating circuit 26a.

[0071] Graph G3 shown in Fig. 8 represents the reverberation of the piezoelectric element 23. Graph G4 shown in Fig. 8 represents the reflected wave that is reflected back from an obstacle present around the vehicle.

[0072] Furthermore, the transfer data generating circuit 26a performs thinning processing on the reception signal output by the receiving circuit 24 based on the time measured by the timer circuit 29, and generates waveform information. near The waveform information is generated with different sampling rates before and after the signal.

[0073] For example, the transfer data generation circuit 26a near The number of samples is thinned out until time T near For example, the waveform information generated by the transfer data generating circuit 26a is generated after the time T near Comparing before and after time T near The number of samples of waveform information generated over time T near is greater than the number of samples of waveform information generated before the

[0074] This process requires real-time performance when the transmission wave transmitted by the piezoelectric element 23 is close, and in order to reduce the waveform information generated by the transfer data generating circuit 26a, the time T near The number of samples of waveform information generated before the time T near The number of samples after time T near The number of samples must be greater than the number of samples before the time T near The number of samples may be thinned out after the elapse of time.

[0075] Furthermore, the transfer data generating circuit 26a detects that the timer circuit 29 has reached the time T gate For example, the transfer data generating circuit 26a generates waveform information until the time T burst This process is for thinning out the transmission wave leakage, which continues to vibrate even after the application of AC voltage has stopped after the piezoelectric element 23 has transmitted the signal. burst is the time during which the AD value remains below the threshold for a certain period of time or more after the piezoelectric element 23 starts transmitting waves.

[0076] The transfer data generation circuit 26a also acquires the generated waveform information and transmission signal information related to the transmission wave transmitted by the piezoelectric element 23, and outputs them to the transfer buffer 27. This process complements the transmission signal from which the above-mentioned transmission wave leak has been thinned out. The transmission signal information includes whether or not there is transmission from the transmitter, the transmission wave mode (for example, modulated / non-modulated, transmission signal length), etc.

[0077] The transfer data generating circuit 26a receives the time T near The transfer data generation circuit 26a generates waveform information with different sampling rates before and after the transmission. In other words, the transfer data generation circuit 26a measures the elapsed time since the transmission of the transmission wave and varies the time resolution according to the measured value. The transfer data generation circuit 26a generates waveform information without losing any waveform information used to detect objects present around the vehicle.

[0078] Furthermore, since the transfer data generation circuit 26a does not output unnecessary information, the transmission time can be reduced. Note that the transfer data generation circuit 26a may measure the elapsed time since the transmission wave was transmitted, and may vary either the number of bits of the peak value or the time resolution, or both, according to the measured value.

[0079] Next, the operation executed by the distance measuring device 20a configured as above will be described. With reference to Fig. 9, a case where the transfer data generating circuit 26a acquires the AD value output by the receiving circuit 24 will be described.

[0080] The transfer data generation circuit 26a acquires the time count output by the clock circuit 29 (step S11). Then, the determination circuit 25a determines whether the time count reaches a predetermined time T near Here, the determination circuit 25a determines whether the measured time is equal to or greater than the predetermined time T near If it is determined that the count time is equal to or greater than the predetermined time T nearIf it is determined that the difference is less than the predetermined value (step S12: No), the process proceeds to step S14.

[0081] The transfer data generating circuit 26a determines whether the clock time reaches a predetermined time T near If it is determined that the number of bits is equal to or greater than this, the number of bits of the AD value output by the receiving circuit 24 is reduced and waveform information is generated (step S13). The transfer data generating circuit 26a outputs the generated waveform information to the transfer buffer 27.

[0082] The transfer data generating circuit 26a determines whether the clock time reaches a predetermined time T near If it is determined that the AD value is less than the predetermined value, the transfer data generating circuit 26a generates waveform information for the AD value output by the receiving circuit 24 (step S14).

[0083] The determination circuit 25a determines whether the time measurement has reached a predetermined time T gate Here, the determination circuit 25a determines whether the measured time is equal to or greater than the predetermined time T gate If it is determined that the measured time is less than the predetermined time T gate If it is determined that the number of times is equal to or greater than the number of times of the first charge (step S15: Yes), the process proceeds to step S16.

[0084] Further, the transfer data generating circuit 26a detects when the clocking time reaches a predetermined time T gate If it is determined that this is the case, transmission signal information relating to the transmission wave transmitted by the piezoelectric element 23 is acquired (step S16). The transfer data generation circuit 26a outputs the acquired transmission signal information to the transfer buffer 27. When step S16 is completed, this process ends.

[0085] As explained above, the distance measuring device 20a of the second embodiment measures the elapsed time since the transmission of the transmission wave, and generates waveform information from a target period other than the period from the start of the measurement until the reverberation generated in the transducer that transmitted the transmission wave stops. This allows the distance measuring device 20a of the second embodiment to reduce the amount of waveform information contained in the reception signal and the loss of real-time performance related to data transmission.

[0086] (Third embodiment) In the first embodiment described above, the transfer data generation circuit 26 generates waveform information based on the result of the determination by the determination circuit 25. In the second embodiment described above, the transfer data generation circuit 26a generates waveform information based on the time when the transmitter / receiver transmitted the transmission wave. In the third embodiment, the transfer data generation circuit 26b generates waveform information based on the received signal output by the receiving circuit 24 and the result of enveloping the received signal.

[0087] Specifically, as shown in Fig. 10, the distance measuring device 20b according to the third embodiment further includes a signal processing circuit 31. The signal processing circuit 31 performs envelope processing to extract the amplitude contour of the received signal output by the receiving circuit 24. The signal processing circuit 31 also performs logarithmic conversion on the envelope-processed received signal (hereinafter also referred to as the envelope value). Furthermore, the signal processing circuit 31 outputs the envelope value and the logarithmically converted received signal (hereinafter referred to as the logarithmic conversion value) to the transfer data generation circuit 26b.

[0088] The determination circuit 25b performs threshold determination on the envelope value output by the signal processing circuit 31. Specifically, the determination circuit 25b sets a threshold α to remove noise, and performs threshold determination on the envelope value output by the signal processing circuit 31.

[0089] When the determination circuit 25b compares the envelope value with the threshold value α and determines that the envelope value is equal to or greater than the threshold value α, the transfer data generation circuit 26b identifies a target period in which the wave height is equal to or greater than the threshold value from the waveform of the time-series received signal output by the receiving circuit 24b, and generates waveform information for the received signal output by the receiving circuit 24b. Note that the transfer data generation circuit 26b does not generate waveform information when the envelope value is less than the threshold value α.

[0090] Here, the processing performed by the transfer data generation circuit 26b will be described with reference to Fig. 11. Fig. 11 is a graph showing waveform information generated by the transfer data generation circuit 26b. The horizontal axis represents time, and the vertical axis represents envelope values. Graph G5 shown in Fig. 11 represents envelope values that are reverberations of the piezoelectric element 23. Graph G6 shown in Fig. 11 represents envelope values that correspond to reflected waves that have returned after being reflected by obstacles present around the vehicle.

[0091] In addition to the generated waveform information, the transfer data generation circuit 26b also acquires saturation state time information indicating the time T3 when the envelope value became saturated and the time T4 when the saturation state was resolved, and outputs this to the transfer buffer 27.

[0092] The transfer data generation circuit 26 generates waveform information without loss of waveform information used to detect objects present around the vehicle. In addition, the transfer data generation circuit 26 does not output unnecessary information, thereby reducing transmission time.

[0093] Next, the operation executed by the distance measuring device 20b configured as above will be described. In Fig. 12, the signal processing circuit 31 performs envelope processing on the AD value output from the piezoelectric element 23 and outputs the resulting envelope value to the transfer data generation circuit 26b.

[0094] The transfer data generation circuit 26b acquires the envelope value output by the signal processing circuit 31 (step S21). Subsequently, the determination circuit 25b determines whether the envelope value is equal to or greater than the threshold value α (step S22). Here, if the determination circuit 25b determines that the envelope value is less than the threshold value α (step S22: No), this processing ends. On the other hand, if the determination circuit 25b determines that the envelope value is equal to or greater than the threshold value α (step S22: Yes), the processing proceeds to step S23.

[0095] When the determination circuit 25b determines that the envelope value is equal to or greater than the threshold value α, the transfer data generation circuit 26b generates waveform information for the envelope value output by the signal processing circuit 31 (step S23). The transfer data generation circuit 26b outputs the generated waveform information to the transfer buffer 27.

[0096] Next, the transfer data generation circuit 26b acquires saturation state time information indicating the time T3 when the envelope value became saturated and the time T4 when the saturation state was resolved (step S24). The transfer data generation circuit 26b outputs the acquired saturation state time information to the transfer buffer 27. When step S24 ends, this process ends.

[0097] As described above, the distance measuring device 20b of the third embodiment generates waveform information based on the received signal and the result of enveloping the received signal. This allows the distance measuring device 20b of the third embodiment to reduce the amount of waveform information contained in the received signal and the loss of real-time data transmission.

[0098] The above-described embodiment can be modified as needed by partially changing the configuration or functions of each of the above-described devices. Therefore, several modifications of the above-described embodiment will be described below as other embodiments. The following mainly focuses on differences from the above-described embodiment, and detailed descriptions of commonalities with the content already described will be omitted. The modifications described below may be implemented individually or in appropriate combination.

[0099] (Variation 1) In the first embodiment described above, the transfer data generation circuit 26 generates waveform information based on the result of the determination made by the determination circuit 25. In the second embodiment, the transfer data generation circuit 26a generates waveform information based on the time at which the ultrasonic transmitter / receiver transmits the transmission wave. The transfer data generation circuit 26 according to the first modification may generate waveform information based on the result of the determination made by the determination circuit 25 and the time at which the ultrasonic transmitter / receiver transmits the transmission wave.

[0100] For example, the transfer data generation circuit 26 receives the time T near If the AD value is equal to or greater than the threshold value α until the time T burst ) generates the AD value output by the receiving circuit 24 as waveform information.

[0101] Here, the processing performed by the transfer data generation circuit 26 will be described with reference to Fig. 13. Fig. 13 is a graph showing waveform information generated by the transfer data generation circuit 26. The horizontal axis represents time, and the vertical axis represents AD values. Graph G7 shown in Fig. 13 represents AD values that are reverberations of the piezoelectric element 23. Graph G8 shown in Fig. 13 represents AD values that correspond to reflected waves that have returned after being reflected by obstacles present around the vehicle.

[0102] Further, the transfer data generating circuit 26 receives the time T near After this time, the AD value to be output by the receiving circuit 24 is generated as waveform information regardless of whether the AD value is equal to or greater than the threshold value α. Thereafter, the transfer data generating circuit 26 outputs the generated waveform information to the transfer buffer 27.

[0103] This processing is intended to receive the received signal mixed with noise, since the peak value of the reflected wave from a distant (long-distance) target object is small and has a voltage level approximately equal to that of noise. Therefore, the transfer data generation circuit 26 generates waveform information without losing any waveform information used to detect objects present around the vehicle.

[0104] Next, a description will be given of the operation executed by the distance measuring device 20 configured as above. In Fig. 14, a case will be described in which the receiving circuit 24 performs analog-to-digital conversion on the voltage output by the piezoelectric element 23 and outputs the AD value to the transfer data generating circuit 26.

[0105] The transfer data generation circuit 26 acquires the AD value output by the receiving circuit 24 and the measured time output by the clock circuit 29 (step S31). near Here, the determination circuit 25 determines whether the measured time is less than the predetermined time T near If it is determined that the measured time is less than the predetermined time T near If it is determined that the difference is less than the predetermined value (step S32: No), the process proceeds to step S34.

[0106] The determination circuit 25 determines whether the AD value is equal to or greater than the threshold value α (step S33). If the determination circuit 25 determines that the AD value is less than the threshold value α (step S33: No), the process returns to step S32. On the other hand, if the determination circuit 25 determines that the AD value is equal to or greater than the threshold value α (step S33: Yes), the process returns to step S35.

[0107] The transfer data generation circuit 26 determines whether the clock time reaches a predetermined time T near If it is determined that the AD value is equal to or greater than this, the transfer data generating circuit 26 generates waveform information for the AD value output by the receiving circuit 24 (step S34).

[0108] When the determination circuit 25 determines that the AD value is equal to or greater than the threshold value α, the transfer data generation circuit 26 generates waveform information for the AD value output by the receiving circuit 24 (step S35). The transfer data generation circuit 26 outputs the generated waveform information to the transfer buffer 27. When steps S34 and S35 are completed, this process ends.

[0109] As described above, the distance measuring device 20 of the first modification generates waveform information based on the result of threshold determination and the time when the transmitter / receiver transmitted the transmitted wave. This allows the distance measuring device 20 of the first modification to reduce the amount of waveform information contained in the received signal and the loss of real-time performance related to data transmission.

[0110] (Variation 2) In the third embodiment described above, the signal processing circuit 31 performs envelope processing to extract the amplitude contour of the received signal output by the receiving circuit 24. The signal processing circuit 31 according to the second modification may further perform quadrature detection processing on the received signal output by the receiving circuit 24.

[0111] The processing performed by the signal processing circuit 31 will now be described with reference to Figs. 15 and 16. Fig. 15 is a graph showing waveform information generated by the signal processing circuit 31. The horizontal axis represents time, and the vertical axis represents the I value. Graph G9 shown in Fig. 15 represents the I value, which is the reverberation of the piezoelectric element 23. Graph G10 shown in Fig. 15 represents the I value corresponding to the reflected wave that has reflected off an obstacle present around the vehicle and returned.

[0112] Fig. 16 is a graph showing waveform information generated by the transfer data generation circuit 26. The horizontal axis represents time, and the vertical axis represents the Q value. Graph G11 shown in Fig. 16 represents the Q value, which is the reverberation of the piezoelectric element 23. Graph G12 shown in Fig. 16 represents the Q value corresponding to the reflected wave that has been reflected back from an obstacle present around the vehicle.

[0113] For example, the signal processing circuit 31 performs quadrature detection processing on the received signal output by the receiving circuit 24 to generate an I value (In-Phase) indicating an in-phase signal and a Q value (Quadrature Phase) indicating a quadrature signal. The signal processing circuit 31 outputs the envelope value, I value, and Q value to the transfer data generating circuit 26. When the signal processing circuit 31 performs envelope processing to extract the outline of the amplitude of the received signal output by the receiving circuit 24, phase information indicating the phase of the received signal is lost. Therefore, the signal processing circuit 31 performs quadrature detection processing to compensate for the lost phase information.

[0114] The transfer data generation circuit 26 generates waveform information when the determination circuit 25 compares AD with the threshold value α and determines that the AD value is equal to or greater than the threshold value α. The transfer data generation circuit 26 also generates waveform information when the determination circuit 25 compares the envelope value with the threshold value α and determines that the envelope value is equal to or greater than the threshold value α. Furthermore, the transfer data generation circuit 26 identifies a target period in which the wave height is equal to or greater than the threshold value based on the I and Q value waveforms generated by the signal processing circuit 31, and outputs the generated waveform information and the I and Q values generated by the signal processing circuit 31 to the transfer buffer 27.

[0115] The transfer data generation circuit 26 generates waveform information without loss of waveform information used to detect objects present around the vehicle. The transfer data generation circuit 26 also outputs I and Q values to the transfer buffer 27 to complement the phase information lost in the envelope value.

[0116] Next, a description will be given of the operation executed by the distance measuring device 20 configured as above. In Fig. 17, a case will be described in which the receiving circuit 24 performs analog-to-digital conversion on the voltage output by the piezoelectric element 23 and outputs the AD value to the transfer data generating circuit 26.

[0117] The transfer data generation circuit 26 acquires the AD value output by the receiving circuit 24 (step S41). Subsequently, the determination circuit 25 determines whether the AD value is equal to or greater than the threshold value α (step S42). Here, if the determination circuit 25 determines that the AD value is less than the threshold value α (step S42: No), this processing ends. On the other hand, if the determination circuit 25 determines that the AD value is equal to or greater than the threshold value α (step S42: Yes), the processing proceeds to step S43.

[0118] When the determination circuit 25 determines that the AD value is equal to or greater than the threshold value α, the transfer data generation circuit 26 generates waveform information for the AD value output by the receiving circuit 24 (step S43). The transfer data generation circuit 26 outputs the generated waveform information to the transfer buffer 27.

[0119] Next, the transfer data generation circuit 26 acquires the I value and Q value generated by the signal processing circuit 31 (step S44). The transfer data generation circuit 26 outputs the acquired I value and Q value to the transfer buffer 27. When step S44 ends, this process ends.

[0120] Next, with reference to FIG. 18, a case will be described in which the signal processing circuit 31 performs envelope processing on the AD value output from the piezoelectric element 23 and outputs the envelope value to the transfer data generating circuit 26.

[0121] The transfer data generation circuit 26 acquires the envelope value output by the signal processing circuit 31 (step S51). Subsequently, the determination circuit 25 determines whether the envelope value is equal to or greater than the threshold value α (step S52). Here, if the determination circuit 25 determines that the envelope value is less than the threshold value α (step S52: No), this processing ends. On the other hand, if the determination circuit 25 determines that the envelope value is equal to or greater than the threshold value α (step S52: Yes), the processing proceeds to step S53.

[0122] When the determination circuit 25 determines that the envelope value is equal to or greater than the threshold value α, the transfer data generation circuit 26 generates waveform information for the envelope value output by the signal processing circuit 31 (step S53). The transfer data generation circuit 26 outputs the generated waveform information to the transfer buffer 27.

[0123] Next, the transfer data generation circuit 26 acquires the I value and Q value generated by the signal processing circuit 31 (step S54). The transfer data generation circuit 26 outputs the acquired I value and Q value to the transfer buffer 27. When step S54 ends, this process ends.

[0124] As described above, the distance measuring device 20 of the modified example 2 outputs the I value and the Q value as a result of the enveloping process. This allows the distance measuring device 20 of the modified example 1 to reduce the amount of waveform information contained in the received signal and the loss of real-time performance related to data transmission.

[0125] Next, waveform information generated by the distance measuring device 20 when the above-described embodiments are implemented in combination will be described with reference to FIGS. 19, 20, 21, 22 and 23. FIG.

[0126] 19 is an example in which the receiving circuit 24 performs analog-to-digital conversion on the voltage output by the piezoelectric element 23 to generate an AD value, and outputs the AD value to the transfer data generating circuit 26. The horizontal axis represents time, and the vertical axis represents the AD value. For example, if the receiving circuit 24 acquires a voltage over a period of 40 msec at a sampling rate of 1.25 MSampling / sec, the number of generated data points will be 50,000.

[0127] Graph G14 shown in Fig. 20 is an example in which the signal processing circuit 31 performs envelope processing to extract the amplitude contour of the received signal (see Fig. 19) output by the receiving circuit 24, to generate an envelope value, and outputs the envelope value to the transfer data generation circuit 26. The horizontal axis represents time, and the vertical axis represents the envelope value. For example, in Fig. 20, the signal processing circuit 31 performs envelope processing on the AD value shown in Fig. 19, and the number of generated data points is 1143.

[0128] Graph G15 shown in Figure 21 is an example in which the transfer data generation circuit 26 generates waveform information for the envelope value (see Figure 20) output by the signal processing circuit 31 as a result of the determination circuit 25 determining that the envelope value is equal to or greater than the threshold value α. The horizontal axis represents time, and the vertical axis represents the envelope value. For example, when the transfer data generation circuit 26 generates waveform information for the envelope value shown in Figure 20, the number of generated data points is 44.

[0129] 22, the transfer data generating circuit 26 outputs the envelope value (see FIG. 20) output by the signal processing circuit 31 over a period of time T near The number of samples is thinned out until time T near This is an example of generating waveform information without thinning out the number of samples after a certain time has elapsed. The horizontal axis represents time, and the vertical axis represents the envelope value.

[0130] In addition, T near is 0.02 seconds. For the sampling rate, time T near There is no change in the sampling rate after time T near The sampling rate before time T near For example, the transfer data generating circuit 26 sets the sampling rate to half of the value after the time T near The number of samples is thinned out until time T nearIf waveform information is generated without thinning the number of samples after this time has elapsed, the number of generated data points will be 710. Note that the sampling rate may be changed by changing the sampling frequency of the receiving circuit 24.

[0131] 23, the transfer data generating circuit 26 generates a time T near In this example, the number of samples is thinned out until the time T counted by the timer circuit 29 has elapsed, and when the envelope value is equal to or greater than the threshold value α, the signal processing circuit 31 outputs an envelope value (see FIG. 20) that is generated as waveform information. near This is an example of a graph in which, after T, the number of samples is not thinned out and the envelope value output by the signal processing circuit 31 is generated as waveform information regardless of whether the envelope value is equal to or greater than the threshold value α. The horizontal axis represents time and the vertical axis represents the envelope value. near is set to 0.02 seconds.

[0132] The transfer data generating circuit 26 calculates the time T measured by the timer circuit 29 for the envelope value shown in FIG. near The number of samples is thinned out until the time T measured by the timer circuit 29 has elapsed. When the envelope value becomes equal to or greater than the threshold value α, the signal processing circuit 31 generates the envelope value as waveform information. near After this time, when the signal processing circuit 31 generates the envelope value to be output as waveform information, the number of generated data points will be 616.

[0133] As described above, the distance measuring device 20 according to the combination can thereby reduce the amount of waveform information contained in the received signal and the loss of real-time performance related to data transmission.

[0134] 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 embodiments can be implemented in various other forms and can be implemented in combination with other embodiments and various other forms. 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, as well as within the scope of the invention and its equivalents as defined in the claims.

[0135] Furthermore, the notation "...circuitry" in the above-described embodiments may be replaced with other notations such as "...assembly," "...device," "...unit," or "...module."

[0136] In each of the above embodiments, the present disclosure has been described as an example configured using hardware, but the present disclosure can also be realized by software in cooperation with hardware.

[0137] Furthermore, each functional block used in the description of each of the above embodiments is typically realized as an LSI (Large Scale Integrated Circuit), which is an integrated circuit. The integrated circuit controls each functional block used in the description of the above embodiments and may have input and output terminals. These may be individually integrated into single chips, or some or all of them may be integrated into a single chip. Here, we refer to an LSI, but depending on the degree of integration, it may also be called an IC, system LSI, super LSI, or ultra LSI.

[0138] Furthermore, the method of integration is not limited to LSI, but may be realized using dedicated circuits or general-purpose processors and memories. It is also possible to use FPGAs (Field Programmable Gate Arrays), which can be programmed after LSI manufacturing, or reconfigurable processors, which allow the connections or settings of circuit cells within LSIs to be reconfigured.

[0139] Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derivative technologies, it is natural that such technology could be used to integrate functional blocks. The application of biotechnology, etc. is also a possibility. [Explanation of symbols]

[0140] 10 Distance measurement control device 20 Ranging device 20a ranging device 20b Ranging device 21 Analog control circuit 22 Transmitting circuit 23 Piezoelectric element 24 Receiver circuit 25 Judgment circuit 25a Judgment circuit 25b Judgment circuit 26 Transfer data generation circuit 26a Transfer data generation circuit 26b Transfer data generation circuit 27 Transfer Buffer 28 Transfer Circuit 29 Timing circuit 30 Vehicle control device 31 Signal processing circuit 201 CPU 202 ROM 203 RAM 204 Interface 205 Flash Memory 206 Bus

Claims

1. A distance measuring device equipped with a transducer, a transmission circuit for transmitting a transmission wave from the transducer; a receiving circuit that outputs a received signal by digitizing a reflected wave of the transmitted wave received by the transducer using a sampling frequency equal to or higher than the frequency of the transmitted wave; a transfer data generation circuit that divides the time-series received signal output by the receiving circuit into a target period where the wave height is equal to or greater than a threshold and a non-target period where the wave height is less than the threshold, performs thinning processing on the received signal in the non-target period, and generates waveform information that indicates the waveform received by the transducer; a transfer circuit that outputs the waveform information generated by the transfer data generation circuit; A ranging device comprising:

2. the transfer data generation circuit identifies a target period in which the wave height is equal to or greater than a threshold value from the waveform of the received signal in time series output by the receiving circuit; 2. The distance measuring device according to claim 1.

3. The transfer data generation circuit identifies, from the time-series received signal output by the receiving circuit, a period in which the wave height is equal to or greater than a threshold value and predetermined periods located before and after the period as the target period.

2. The distance measuring device according to claim 1.

4. The waveform information includes at least one of a start time of the target period, an end time of the target period, and a sample period of the target period.

4. A distance measuring device according to claim 1.

5. the transfer data generation circuit measures the elapsed time since the transmission of the transmission wave; changing the generation process of waveform information according to the measured value; 4. A distance measuring device according to claim 1.

6. the transfer data generation circuit measures the elapsed time since the transmission of the transmission wave; Identifying the target period according to the measured value.

4. A distance measuring device according to claim 1.

7. the transfer data generation circuit measures the elapsed time since the transmission of the transmission wave; Depending on the measured value, either the number of bits of the peak value or the time resolution, or both, are varied.

7. A distance measuring device according to claim 5 or 6.

8. the transfer data generation circuit measures the elapsed time from the transmission of the transmission wave, and defines the target period as a period other than the period from the start of the measurement until the reverberation generated in the transducer that transmitted the transmission wave ceases.

4. A distance measuring device according to claim 1.

9. The waveform information generated by the transfer data generating circuit includes information on the transmission signal.

9. The distance measuring device according to claim 8.

10. a signal processing circuit that performs envelope detection processing on the received signal output by the receiving circuit and generates an envelope signal that is a processing result of the envelope detection processing; 10. A distance measuring device according to claim 1.

11. a signal processing circuit that performs an envelope detection process and then a logarithmic conversion process on the received signal output from the receiving circuit, and generates an envelope signal that is a processing result of the logarithmic conversion process; 10. A distance measuring device according to claim 1.

12. The transfer data generation circuit A period in which the wave height of the envelope signal is equal to or greater than a threshold value and predetermined periods located before and after the period are identified as the target period.

12. A distance measuring device according to claim 10 or 11.

13. the transfer data generation circuit outputs the envelope signal generated by the signal processing circuit; 13. A distance measuring device according to claim 12.

14. The transfer data generation circuit During a period in which the received signal or the envelope signal is in a saturated state, information indicating the saturated state and a start time and an end time of the period are output as waveform information.

14. A distance measuring device according to any one of claims 10 to 13.

15. a signal processing circuit that performs quadrature detection processing on the received signal output by the receiving circuit and generates an I value and a Q value that are the processing results of the quadrature detection processing; 15. A distance measuring device according to any one of claims 1 to 14.

16. the transfer data generation circuit specifies a period in which the wave heights of the I value and the Q value are equal to or greater than a threshold as the target period; 16. A distance measuring device according to claim 15.

17. the transfer data generation circuit outputs the I value and the Q value generated by the signal processing circuit.

17. A distance measuring device according to claim 15 or 16.

18. A distance measurement method performed by a distance measurement device equipped with a transducer, comprising: a transmitting step of transmitting a transmission wave from the transducer; a receiving step of digitizing a reflected wave of the transmission wave received by the transducer using a sampling frequency equal to or higher than the frequency of the transmission wave and outputting a received signal; a transfer data generation step of dividing the time-series received signals outputted in the receiving step into a target period where the wave height is equal to or greater than a threshold and a non-target period where the wave height is less than the threshold, and performing a thinning process on the received signals in the non-target period to generate waveform information indicating the waveform received by the transducer; a transfer step of outputting the waveform information generated in the transfer data generation step; A ranging method including:

19. A computer that controls a distance measuring device equipped with a transducer, a transmission circuit for transmitting a transmission wave from the transducer; a receiving circuit that outputs a received signal by digitizing a reflected wave of the transmitted wave received by the transducer using a sampling frequency equal to or higher than the frequency of the transmitted wave; a transfer data generation circuit that divides the time-series received signal output by the receiving circuit into a target period where the wave height is equal to or greater than a threshold and a non-target period where the wave height is less than the threshold, performs thinning processing on the received signal in the non-target period, and generates waveform information that indicates the waveform received by the transducer; a transfer circuit that outputs the waveform information generated by the transfer data generation circuit; A program that makes it work.

20. A ranging system mounted on a vehicle, comprising: A distance measuring device comprising one or more distance measuring devices according to any one of claims 1 to 17, a distance measurement control device that detects objects around the vehicle based on the waveform information output from one or more of the distance measurement devices; a vehicle control device that controls the vehicle in accordance with the detection result of the object; A ranging system comprising:

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