Object detection system and object detection device

Abstract

This invention provides an object detection system for improving the recognizability of transmitted waves. The object detection system includes multiple object detection devices, each of which includes: a transmitting unit that transmits a transmitted wave, encoded based on one or more combinations of multiple waves that are frequency-modulated differently from those of other object detection devices, approximately simultaneously with the other object detection devices, wherein the frequency modulation is based on multiple linear frequency modulated signals whose frequencies vary in mutually different patterns; a receiving unit that receives a received wave as a transmitted wave reflected back according to an object; and a detection processing unit that detects information related to the object based on information obtained as a result of transmitting and receiving the transmitted and received waves.

Description

Technical Field

[0001] This invention relates to an object detection system and an object detection device. Background Technology

[0002] Previously, it was known that there were techniques that transmitted ultrasound waves as transmitting waves and received ultrasound waves as receiving waves that were reflected back by objects, thereby detecting information related to objects, such as the distance to the object.

[0003] Patent Document 1: International Publication No. WO2011 / 102130

[0004] In the aforementioned prior art, systems often employ multiple object detection devices for detecting information related to objects. In such systems, to detect object-related information in greater detail, transmission waves are typically sent approximately simultaneously (in parallel) from each of the multiple object detection devices. In this case, to suppress interference, it is desirable to improve the recognizability of the transmitted waves. Summary of the Invention

[0005] Therefore, one of the objectives of this invention is to provide an object detection system and object detection device that can improve the recognizability of transmitted waves.

[0006] An object detection system, as an example of the present invention, comprises: a plurality of object detection devices, each of the plurality of object detection devices comprising: a transmitting unit that transmits a transmitted wave, encoded based on a single or two or more combinations of multiple waves, each of which is different from those of the other object detection devices, substantially simultaneously with the other object detection devices, wherein the frequency modulation is based on multiple linear frequency modulated signals whose frequencies vary in mutually different modes; a receiving unit that receives a received wave as a transmitted wave reflected back by an object; and a detection processing unit that detects information related to the object based on information obtained as a result of the transmission and reception of the transmitted and received waves.

[0007] According to the object detection system described above, a transmitted wave can be transmitted based on one or more combinations of multiple frequency-modulated waves, encoded in a manner that includes appropriate identification information. The frequency modulation is based on multiple linear frequency modulated signals whose frequencies vary in mutually different patterns. Therefore, the recognizability of the transmitted wave can be improved.

[0008] In the aforementioned object detection system, the transmitting unit transmits a transmitted wave approximately simultaneously with other object detection devices. This transmitted wave is encoded based on one or more combinations of multiple waves that are different from those of other object detection devices, and the frequency modulation is based on multiple linear frequency modulated signals. The phase modulation is performed by assigning mutually different phases. This structure, employing phase modulation simultaneously, increases the number of codes that can be represented, thus further improving the recognizability of the transmitted wave.

[0009] Furthermore, in the aforementioned object detection system, the multiple linear frequency modulated (LFM) signals include: a first LFM signal whose frequency monotonically increases, and a second LFM signal whose frequency monotonically decreases. Based on this structure, the recognizability of the transmitted wave can be easily improved using only two LFM signals with simple waveforms.

[0010] Furthermore, the object detection system described above also includes a correlation processing unit. This unit obtains a correlation value representing the similarity between the transmitted and received waves. The detection processing unit detects object-related information based on a comparison between the correlation value and a threshold. With this structure, object-related information can be detected with high precision using the correlation value.

[0011] Furthermore, in the aforementioned object detection system, the detection processing unit detects the distance to the object based on the difference between the time the transmitted wave is emitted and the time the received wave is received, thus providing information related to the object. With this structure, useful information such as the distance to the object can be obtained as object-related information.

[0012] Furthermore, as another example of the present invention, the object detection system includes multiple object detection devices, each of which includes: a transmitting unit that transmits a transmitted wave approximately simultaneously with other object detection devices, encoded based on a single or two or more combinations of multiple waves that are frequency-modulated and phase-modulated, which are different from those of other object detection devices, wherein the frequency modulation is based on a single linear frequency modulated signal whose frequency varies with a predetermined pattern, and the phase modulation is performed by allocating mutually different phases; a receiving unit that receives a received wave as a transmitted wave reflected back by an object; and a detection processing unit that detects information related to the object based on information obtained as a result of the transmission and reception of the transmitted and received waves.

[0013] According to the object detection system described above, it is possible to transmit a wave based on a single or combination of multiple waves that have undergone frequency modulation of a single linear frequency modulated signal that varies in a prescribed pattern and phase modulation of each wave with different phase assignments, after encoding the wave in a manner that includes appropriate identification information. Therefore, the recognizability of the transmitted wave can be improved.

[0014] In the object detection system described above, the prescribed pattern of a single linear frequency modulated (LFM) signal is a pattern in which the frequency monotonically increases or decreases. Based on this structure, the recognizability of the transmitted wave can be easily improved using two LFM signals with simple waveforms.

[0015] Furthermore, the object detection system described above also includes a correlation processing unit. This unit obtains a correlation value representing the similarity between the transmitted and received waves. The detection processing unit detects object-related information based on a comparison between the correlation value and a threshold. With this structure, object-related information can be detected with high precision using the correlation value.

[0016] Furthermore, in the aforementioned object detection system, the detection processing unit detects the distance to the object based on the difference between the time the transmitted wave is emitted and the time the received wave is received, thus providing information related to the object. With this structure, useful information such as the distance to the object can be obtained as object-related information.

[0017] Furthermore, as another example of the present invention, the object detection apparatus includes: a transmitting unit that transmits a transmitted wave, approximately simultaneously with other object detection apparatuses, based on a single or two or more combinations of multiple waves that are respectively frequency-modulated, which are different from those of other object detection apparatuses, wherein the frequency modulation is based on multiple linear frequency modulated signals whose frequencies vary in mutually different modes; a receiving unit that receives a received wave as a transmitted wave reflected back by an object; and a detection processing unit that detects information related to the object based on information obtained as a result of the transmission and reception of the transmitted and received waves.

[0018] According to the object detection device described above, it is possible to transmit a wave based on one or more combinations of multiple waves that have undergone frequency modulation by multiple linear frequency modulated signals that vary in different modes, after encoding them in a manner that includes appropriate identification information. Therefore, the recognizability of the transmitted wave can be improved.

[0019] Furthermore, as another example of the present invention, the object detection apparatus includes: a transmitting unit that transmits a transmitted wave, encoded based on a single or two or more combinations of multiple waves that are different from those of other object detection devices and are subjected to frequency modulation and phase modulation, approximately simultaneously with other object detection devices; the frequency modulation is based on a single linear frequency modulated signal whose frequency varies in a predetermined pattern; and the phase modulation is performed by allocating phases that are different from each other; a receiving unit that receives a received wave as a transmitted wave reflected back by an object; and a detection processing unit that detects information related to the object based on information obtained as a result of transmitting and receiving the transmitted and received waves.

[0020] According to the object detection device described above, a transmitted wave can be transmitted based on one or more combinations of multiple waves that have undergone frequency modulation and phase modulation, after being encoded in a manner that includes appropriate identification information. The frequency modulation is based on a single linear frequency modulated signal whose frequency varies in a predetermined pattern, and the phase modulation is performed by assigning mutually different phases. Therefore, the recognizability of the transmitted wave can be improved. Attached Figure Description

[0021] Figure 1 This is an illustrative and schematic diagram showing the appearance of a vehicle equipped with the object detection system of the first embodiment as viewed from above.

[0022] Figure 2 This is an exemplary and schematic block diagram showing the simplified hardware structure of the ECU (electronic control unit) of the object detection system and the object detection device in the first embodiment.

[0023] Figure 3 This is an illustrative and schematic diagram outlining the techniques used by the object detection apparatus of the first embodiment to detect the distance to an object.

[0024] Figure 4 This is an illustrative and schematic block diagram showing the detailed structure of the object detection device according to the first embodiment.

[0025] Figure 5 This is an illustrative and schematic diagram representing the first linear frequency modulation signal of the first embodiment.

[0026] Figure 6 This is an illustrative and schematic diagram representing the second linear frequency modulation signal of the first embodiment.

[0027] Figure 7 This is an illustrative and schematic diagram showing an example of a modulation pattern corresponding to the identification information of the first embodiment.

[0028] Figure 8This is an exemplary and schematic flowchart illustrating a series of processes performed by the object detection system of the first embodiment in order to detect the distance to an object.

[0029] Figure 9 This is an illustrative and schematic diagram showing an example of the modulation method of the second embodiment.

[0030] Figure 10 This is an illustrative and schematic diagram showing an example of a modulation pattern corresponding to the identification information of the second embodiment.

[0031] Figure 11 This is an exemplary and schematic diagram illustrating a modulation method of a variant.

[0032] Explanation of reference numerals in the attached figures

[0033] 200, 201, 202, 203, 204… Object detection device; 401, 403, 405… Transmitting unit; 402, 404, 406… Receiving unit; 426… Related processing unit; 429… Detection processing unit. Detailed Implementation

[0034] The embodiments and modifications of the present invention will be described below with reference to the accompanying drawings. The structures of the embodiments and modifications described below, as well as the functions and effects brought about by the structures, are merely examples and are not limited to the following description.

[0035] <First Implementation Method>

[0036] Figure 1 This is an exemplary and schematic diagram showing the vehicle 1 of the object detection system of the first embodiment as viewed from above.

[0037] like Figure 1 As shown, the object detection system includes an ECU (electronic control unit) 100 installed inside a vehicle 1, which has four wheels including a pair of front wheels 3F and a pair of rear wheels 3R, and object detection devices 201 to 204 installed on the exterior of the vehicle 1.

[0038] exist Figure 1 In the example shown, as an example, the object detection devices 201 to 204 are installed at different positions at the rear end of the vehicle body 2, which is the exterior of the vehicle 1, such as the rear bumper.

[0039] In the first embodiment, the object detection devices 201 to 204 have the same hardware structure and function. Therefore, for the sake of simplicity, they will sometimes be collectively referred to as object detection devices 201 to 204 and referred to as object detection device 200.

[0040] Furthermore, in the first embodiment, the location of the object detection device 200 is not limited to... Figure 1 The example shown illustrates this. The object detection device 200 can also be located at the front end of the vehicle body 2, such as the front bumper, or on the side of the vehicle body 2, or at two or more of the rear bumper, front bumper, and side. Furthermore, in the first embodiment, the number of object detection devices 200 is not limited to this. Figure 1 The example shown. However, the technique of the first embodiment is effective for structures with multiple object detection devices 200.

[0041] The object detection system of the first embodiment, based on the structure described below, performs ultrasonic wave transmission and reception, obtains the time difference between the transmission and reception, etc., thereby detecting objects, including people, existing in the surrounding environment (e.g., described later). Figure 2 Information related to the object O shown.

[0042] Figure 2 This is an exemplary and schematic block diagram showing the hardware structure of the ECU100 of the object detection system and the object detection device 200 of the first embodiment.

[0043] like Figure 2 As shown, ECU 100 has the same hardware structure as a typical computer. More specifically, ECU 100 includes an input / output device 110, a storage device 120, and a processor 130.

[0044] Input / output device 110 is used to enable communication between ECU 100 and external devices (in... Figure 1 The example shown is the interface for sending and receiving information between the object detection devices 200.

[0045] Storage device 120 includes main storage devices such as ROM (Read Only Memory) and RAM (Random Access Memory), and / or auxiliary storage devices such as HDD (Hard Disk Drive) and SSD (Solid State Drive).

[0046] The processor 130 is responsible for various processes performed in the ECU 100. The processor 130 includes, for example, a computing device such as a CPU (Central Processing Unit). The processor 130 reads and executes computer programs stored in the storage device 120, thereby implementing various functions such as parking assistance.

[0047] On the other hand, such as Figure 2As shown, the object detection device 200 includes a transceiver 210 and a control unit 220. According to the above structure, the object detection device 200 is configured as an example of an onboard sonar, which is an onboard sensor that detects the distance to objects existing around the vehicle 1.

[0048] The transceiver 210 has a piezoelectric element and a vibrator 211, through which ultrasonic waves are transmitted and received.

[0049] More specifically, transceiver 210 transmits ultrasonic waves generated by the vibration of oscillator 211 as transmitted waves, and receives the vibrations of oscillator 211 caused by the reflection of the transmitted ultrasonic waves from an external object as received waves. Figure 2 In the example shown, the road surface RS and the object O disposed on the road surface RS are examples of objects that can reflect ultrasonic waves from transceiver 210.

[0050] In addition, Figure 2 The example shown illustrates a structure in which both the transmitting and receiving of a wave are implemented using a single transceiver 210 with a single oscillator 211. However, the technique of the first embodiment can of course also be applied to structures that separate the transmitting and receiving sides, such as structures that have a first oscillator for transmitting the wave and a second oscillator for receiving the wave.

[0051] The control unit 220 has the same hardware structure as a typical computer. More specifically, the control unit 220 includes an input / output device 221, a storage device 222, and a processor 223.

[0052] Input / output device 221 is used to enable communication between control unit 220 and external devices (in...) Figure 1 The example shown is the interface for sending and receiving information between ECU100 and transceiver 210.

[0053] Storage device 222 includes main storage devices such as ROM and RAM, and / or auxiliary storage devices such as HDD or SSD.

[0054] Processor 223 is responsible for various processes executed in control unit 220. Processor 223 includes, for example, an arithmetic unit such as a CPU. Processor 223 reads and executes computer programs stored in storage device 333, thereby performing various functions.

[0055] Here, the object detection device 200 of the first embodiment detects the distance to an object using a technique known as the so-called TOF (Time of Flight) method, as information related to the object. As detailed below, the TOF method is a technique that calculates the distance to an object by taking into account the difference between the time when the transmitted wave is sent (more specifically, the start of transmission) and the time when the received wave is received (more specifically, the start of reception).

[0056] Figure 3 This is an illustrative and schematic diagram illustrating the outline of the technology used by the object detection device 200 of the first embodiment to detect the distance to an object.

[0057] exist Figure 3 In the example shown, the time variation of the signal level (e.g., amplitude) of the ultrasonic waves transmitted and received by the object detection device 200 of the first embodiment is illustrated in graphical form. Figure 3 In the chart shown, the horizontal axis corresponds to time, and the vertical axis corresponds to the signal level of the signals transmitted and received by the object detection device 200 via the transceiver 210 (oscillator 211).

[0058] exist Figure 3 In the diagram shown, the solid line L11 illustrates an example of the envelope (envelope waveform) representing the time-varying signal level of the signals transmitted and received by the object detection device 200, i.e., the degree of vibration of the oscillator 211. From this solid line L11, it can be seen that the oscillator 211 is driven to vibrate at time t0 for a time Ta, thus ending the transmission of the transmitted wave at time t1. Then, during the time Tb before reaching time t2, the vibration of the oscillator 211, caused by inertia, decays and continues. Therefore, in Figure 3 In the chart shown, time Tb corresponds to the so-called reverberation time.

[0059] At time t4, after time Tp has elapsed from the start of the transmitted wave (time t0), the vibration intensity of oscillator 211 reaches a peak value exceeding (or surpassing) the predetermined threshold Th1 represented by the dashed line L21. This threshold Th1 is used to identify whether the vibration of oscillator 211 is that of an object being detected (e.g., [object name missing]). Figure 2 The received wave is caused by the reflection of the transmitted wave from the object O shown, or by the reception of the received wave from an object other than the object being examined (e.g., an object outside the object being examined). Figure 2 The received wave is a pre-set value caused by the reflection of the transmitted wave back from the road surface (RS).

[0060] In addition, Figure 3While an example of setting the threshold Th1 to a constant value that does not change over time is shown, in the first embodiment, the threshold Th1 may also be set to a value that changes over time.

[0061] Here, vibrations with peak values ​​exceeding (or higher than) the threshold Th1 can be considered as vibrations caused by the reception of a transmitted wave reflected back by an object being detected. On the other hand, vibrations with peak values ​​below (or less than) the threshold Th1 can be considered as vibrations caused by the reception of a transmitted wave reflected back by an object other than the object being detected.

[0062] Therefore, as can be seen from the solid line L11, the vibration of the oscillator 211 at time t4 is caused by the reception of the transmitted wave reflected back by the object being detected.

[0063] Furthermore, in solid line L11, the vibration of oscillator 211 decays after time t4. Therefore, time t4 corresponds to the time when the reception of the transmitted wave reflected back by the object being detected ends, or in other words, the time when the transmitted wave last transmitted at time t1 returns as the received wave.

[0064] Furthermore, in solid line L11, the time t3, which is the starting point of the peak at time t4, corresponds to the time at which the received wave of the transmitted wave reflected back by the object being detected begins to be received; in other words, it corresponds to the time at which the transmitted wave initially transmitted at time t0 returns as a received wave. Therefore, in solid line L11, the time ΔT between time t3 and time t4 is equal to the time Ta, which is the transmission time of the transmitted wave.

[0065] Based on the above, in order to determine the distance to the object being detected using the Time-of-Flight (TOF) method, it is necessary to calculate the time Tf between the time t0 when the transmitted wave begins to be transmitted and the time t3 when the received wave begins to be received. This time Tf can be obtained by subtracting the time ΔT, which is equal to the transmission time Ta, from the time Tp, which is the difference between time t0 and the time t4 when the signal level of the received wave reaches a peak exceeding the threshold Th1.

[0066] The moment t0 when the transmitted wave begins to be transmitted can be easily determined as the moment when the object detection device 200 starts operating, and the transmission time Ta of the transmitted wave is predetermined by setting, etc. Therefore, in order to determine the distance of the object from the detected object by the TOF method, it becomes important to determine the moment t4 when the signal level of the received wave reaches a peak value exceeding the threshold Th1.

[0067] However, in the structure described above, which includes multiple object detection devices 200, in order to detect information related to objects existing in the surrounding environment in greater detail, transmission waves are often transmitted approximately simultaneously (in parallel) from each of the multiple object detection devices 200. In this case, it is desirable to improve the recognizability of the transmitted waves in order to suppress interference, etc.

[0068] Therefore, the first embodiment improves the recognizability of the transmitted wave by configuring the object detection device 200 as follows.

[0069] Figure 4 This is an illustrative and schematic block diagram showing the detailed structure of the object detection device 200 according to the first embodiment.

[0070] like Figure 4 As shown, in the first embodiment, as a transmitting side structure, a plurality of (three for example) transmitting units 401, 403 and 405 are provided, and as a receiving side structure, a plurality of (three for example) receiving units 402, 404 and 406 are provided.

[0071] Here, in Figure 4 Although the transmitting and receiving side structures are illustrated separately, this illustration is merely for ease of explanation. Therefore, in Figure 4 In the examples shown, combinations of transmitting unit 401 and receiving unit 402, transmitting unit 403 and receiving unit 404, and transmitting unit 405 and receiving unit 406 respectively constitute an object detection device 200. However, although the above is repeated, the technology of the first embodiment can of course also be applied to structures in which the transmitting side structure and the receiving side structure are separated.

[0072] In addition, Figure 4 The diagrams show three structures for the transmitting side and three structures for the receiving side, but in the first embodiment, the structures can also be the same as those for the transmitting side. Figure 1 The four object detection devices 200 shown correspond to each other, with one structure on the transmitting side and one structure on the receiving side.

[0073] Furthermore, in the first embodiment... Figure 4 At least a portion of the structure shown is implemented as a result of hardware and software cooperation; more specifically, it is implemented as a result of the processor 223 of the object detection device 200 reading from the storage device 222 and executing a computer program. However, in this embodiment, Figure 4 At least a portion of the structure shown can also be implemented using dedicated hardware (circuitry).

[0074] First, the structure of the transmitting side of the object detection device 200 will be explained.

[0075] like Figure 4 As shown, the transmitting unit 401 includes a transmitter 411, a carrier output unit 412, a modulation mode determination unit 413, a multiplier 414, and an amplifier circuit 415.

[0076] Furthermore, transmitting units 403 and 405 respectively possess transmitters 431 and 451 identical to those in transmitter 411. Figure 4 Although the illustrations of transmitters 431 and 451 are omitted due to space constraints, transmitters 403 and 405 have the same structure as transmitter 401, except for transmitters 431 and 451.

[0077] The transmitter 411 is composed of the aforementioned oscillator 211, through which a transmission wave corresponding to the transmission signal output (amplified) from the amplifier circuit 415 is transmitted.

[0078] Here, in the first embodiment, the transmitter 411 is configured, for example, based on the control of the ECU 100, to transmit a transmission wave virtually simultaneously with the transmitters 431 and 451 of the other object detection device 200. Therefore, in the first embodiment, in order to determine the source of the transmission wave that returns as a received wave, it is necessary to assign identification information to the transmission wave.

[0079] Therefore, in the first embodiment, for example, a carrier wave such as a sine wave is modulated with a modulation mode corresponding to the identification information to be assigned to the transmitted wave, thereby generating a transmitted wave encoded in a manner that includes the identification information.

[0080] More specifically, the carrier output unit 412 outputs a carrier wave, such as a sine wave, which forms the basis of the transmitted wave. Furthermore, the modulation mode determination unit 413 determines the modulation mode of the carrier wave corresponding to the identification information, which is a code consisting of a continuous bit string of, for example, 0 or 1 bits, to be assigned to the transmitted wave. Moreover, the multiplier 414 multiplies the output from the modulation mode determination unit 413 by the output from the carrier output unit 412, thereby modulating the carrier wave to generate a transmitted wave encoded in a manner containing the identification information.

[0081] Furthermore, in the first embodiment, the code length of the identification information is in Figure 1 In the structure shown, which has four object detection devices 200, it is set to be able to recognize at least the four object detection devices 200 with each other.

[0082] In the first embodiment, the carrier modulation mode uses the following... Figure 5 as well as Figure 6The decision is made by multiple (two for example) different linear frequency modulated signals, as shown.

[0083] Figure 5 This is an illustrative and schematic diagram showing the first linear frequency modulation signal of the first embodiment. Figure 6 This is an illustrative and schematic diagram representing the second linear frequency modulation signal of the first embodiment.

[0084] like Figure 5 As shown, the first linear frequency modulated signal is a signal whose frequency increases monotonically (more specifically, linearly) from f1 to f2 over a specified period T (refer to solid line L500). Additionally, as... Figure 6 As shown, the second linear frequency modulated signal is a signal whose frequency decreases monotonically (more specifically, linearly) from f2 to f1 over a specified period T (refer to solid line L600).

[0085] Here, in the first embodiment, a transmission wave encoded in a manner that includes identification information is generated based on two or more combinations of a first wave of a carrier that is frequency-modulated during a period T based on a first linear frequency modulation signal and a second wave of a carrier that is frequency-modulated during a period T based on a second linear frequency modulation signal.

[0086] For example, in the first embodiment, a bit "1" is assigned to the first wave and a bit "0" is assigned to the second wave. In this case, the transmitted wave, for example, encoded with identification information consisting of a bit string such as "1101", is transmitted via the following... Figure 7 It is generated by modulating the carrier wave in the modulation mode shown.

[0087] Figure 7 This is an illustrative and schematic diagram showing an example of a modulation pattern corresponding to the identification information of the first embodiment.

[0088] exist Figure 7 In the example shown, "UP" represents a first linear frequency modulated (LFM) signal whose frequency monotonically increases, and "DOWN" represents a second LFM signal whose frequency monotonically decreases. Additionally, in... Figure 7 In the example shown, as described above, a first fluctuation bit "1" is assigned to the frequency modulation based on the first linear frequency modulation signal, and a second fluctuation bit "0" is assigned to the frequency modulation based on the second linear frequency modulation signal.

[0089] Based on the above, such as Figure 7As shown, the transmitted wave, which is encoded in a manner that includes identification information consisting of a bit string such as "1101", is formed by combining the aforementioned first wave based on the first linear frequency modulation signal ("UP"), the aforementioned first wave based on the first linear frequency modulation signal ("UP"), the aforementioned second wave based on the second linear frequency modulation signal ("DOWN"), and the aforementioned first wave based on the first linear frequency modulation signal ("UP") in this order.

[0090] Therefore, in the first embodiment, when the identification information to be assigned to the transmitted wave is determined to be a bit string code such as "1101", the modulation mode determination unit 413 determines the mode in which the frequency modulation based on the first linear frequency modulation signal, the frequency modulation based on the first linear frequency modulation signal, the frequency modulation based on the second linear frequency modulation signal, and the four frequency modulations based on the first linear frequency modulation signal are executed in that order as the modulation mode of the carrier.

[0091] return Figure 4 The amplifier circuit 415 amplifies the transmission signal output from the multiplier 414 and outputs the amplified transmission signal to the transmitter 411. Thus, in the first embodiment, the transmission structure of the object detection device 200 is based on a transmission wave encoded from two or more combinations of two waves that are different from those of other object detection devices 200, each of which is modulated by the frequencies of two linear frequency modulation signals that vary in different frequency patterns.

[0092] Next, the structure of the receiving side of the object detection device 200 will be described.

[0093] like Figure 4 As shown, the receiving unit 402 includes a receiver 421, an amplifier circuit 422, a filter processing unit 423, an identification unit 424, and multiple (three in one example) signal processing systems 425A to 425C.

[0094] In addition, receiving units 404 and 406 respectively have receivers 441 and 461 that are identical to receiver 421. Figure 4 Although the illustrations of receivers 441 and 461 are omitted due to space constraints, receivers 404 and 406, in addition to receivers 441 and 461, also have the same structure as receiver 402.

[0095] The receiver 421 is composed of the aforementioned oscillator 211, through which the transmitted wave reflected by the object is received as the received wave.

[0096] Amplifier circuit 422 amplifies the received signal, which is the signal corresponding to the received wave received by receiver 421.

[0097] The filtering unit 423 performs filtering processing on the received signal amplified by the amplifier circuit 422. This filtering processing includes noise suppression and Doppler frequency shift correction.

[0098] Here, in the first embodiment, as described above, multiple transmit waves are actually transmitted simultaneously from the multiple transmitters 411, 431, and 451. Therefore, the receive wave received by the receiver 421 is formed by at least partially overlapping with multiple waves corresponding to the multiple transmit waves transmitted from the multiple transmitters 411, 431, and 451.

[0099] Therefore, in the first embodiment, signal processing systems 425A to 425C are provided in the same number as transmitters 411, 431, and 451. Each of the signal processing systems 425A to 425C includes a correlation processing unit 426, an envelope processing unit 427, a threshold processing unit 428, and a detection processing unit 429. According to the above structure, the signal processing systems 425A to 425C perform the function of determining the relationship between the received wave received via receiver 421 and the multiple transmitted waves transmitted via transmitters 411, 431, and 451, and the function of detecting information related to an object based on the determined relationship.

[0100] The correlation processing unit 426 obtains a correlation value corresponding to the similarity of the identification information of the transmitted and received waves based on the transmitted signal obtained from the structure on the transmitting side and the received signal that has undergone filtering processing by the filtering processing unit 423. The correlation value is calculated based on generally known correlation functions, etc.

[0101] Furthermore, the envelope processing unit 427 calculates the envelope of the waveform of the signal corresponding to the correlation value obtained by the correlation processing unit 426.

[0102] Furthermore, the threshold processing unit 428 compares the value of the envelope obtained by the envelope processing unit 427 with a predetermined threshold, and based on the comparison result, determines whether the identification information of the transmitted wave and the received wave is similar at a predetermined level or higher.

[0103] Furthermore, based on the processing results of the threshold processing unit 428, the detection processing unit 429 determines the moment when the similarity between the identification information of the transmitted wave and the received wave reaches a predetermined level or higher, that is, the moment when the signal level of the received wave, which is the transmitted wave, returns through reflection and reaches a peak value exceeding the threshold (e.g., Figure 2 At time t4, the distance to the object is detected using the Time-of-Flight (TOF) method as information related to the object.

[0104] Here, in the first embodiment, the correlation processing unit 426 of the signal processing system 425A is configured to obtain a correlation value using the transmitted signal obtained from the transmitting unit 401. Therefore, the correlation value obtained by the correlation processing unit 426 of the signal processing system 425A becomes a value that reflects the similarity to the transmitted wave transmitted from the transmitter 411.

[0105] Similarly, the correlation processing unit 426 of the signal processing system 425B is configured to obtain correlation values ​​using the transmitted signal obtained from the transmitting unit 403, and the correlation processing unit 426 of the signal processing system 425C is configured to obtain correlation values ​​using the transmitted signal obtained from the transmitting unit 405. Therefore, the correlation value obtained by the correlation processing unit 426 of the signal processing system 425B becomes a value reflecting the similarity to the transmitted wave transmitted from the transmitter 431, and the correlation value obtained by the correlation processing unit 426 of the signal processing system 425C becomes a value reflecting the similarity to the transmitted wave transmitted from the transmitter 451.

[0106] Therefore, in the first embodiment, the detection processing unit 429 of the signal processing system 425A determines the moment when the signal level of the received wave, which is reflected back from the transmitter 411 and thus received by the receiver 421, reaches a peak value exceeding a threshold. Similarly, the detection processing unit 429 of the signal processing system 425B determines the moment when the signal level of the received wave, which is reflected back from the transmitter 431 and thus received by the receiver 421, reaches a peak value exceeding a threshold, and the detection processing unit 429 of the signal processing system 425C determines the moment when the signal level of the received wave, which is reflected back from the transmitter 451 and thus received by the receiver 421, reaches a peak value exceeding a threshold.

[0107] Thus, in the first embodiment, three signal processing systems 425A to 425C are used to appropriately determine the times when the transmitted wave from transmitter 411 returns to the receiver 421 after reflection, the times when the transmitted wave from transmitter 431 returns to the receiver 421 after reflection, and the times when the transmitted wave from transmitter 451 returns to the receiver 421 after reflection. Furthermore, the distance to the object is appropriately detected based on the difference between the respective transmission and reception times.

[0108] Based on the above structure, the object detection system of the first embodiment is as follows: Figure 8 The process is executed as shown to detect information related to the object.

[0109] Figure 8 This is an exemplary and schematic flowchart illustrating a series of processes performed by the object detection system of the first embodiment in order to detect the distance to an object.

[0110] like Figure 8 As shown, in the first embodiment, in S801, each object detection device 200 of the object detection system determines the modulation mode of the carrier corresponding to the identification information to be assigned to the transmitted wave by the modulation mode determination unit 413.

[0111] Furthermore, in S802, each object detection device 200 transmits a transmitted wave generated by modulating the carrier wave with the modulation mode determined in S801 via transceiver 210.

[0112] Furthermore, in S803, each object detection device 200 receives the received wave, which is the result of the transmitted wave sent in S802 being reflected back by the object, via the transceiver 210.

[0113] Furthermore, in S804, each object detection device 200 obtains a correlation value corresponding to the similarity of the identification information of the transmitted wave and the received wave through the correlation processing unit 426.

[0114] Furthermore, in S805, each object detection device 200, through the detection processing unit 829, detects the distance to the object based on the comparison result between the correlation value (envelope) obtained in S804 and the threshold. Then, the processing ends.

[0115] As described above, the object detection system of the first embodiment includes a plurality of object detection devices 200. Each of the plurality of object detection devices 200 has the same structure.

[0116] For example, in the first embodiment, one of the plurality of object detection devices 200 includes a transmitting unit 401, a receiving unit 402, and a detection processing unit 429. The transmitting unit 401 transmits a transmitted wave, encoded based on two or more combinations of multiple waves, each frequency-modulated, that differ from those of the other object detection devices 200, approximately simultaneously with the other object detection devices 200. The frequency modulation is based on multiple linear frequency modulated signals that vary in different frequency patterns. The receiving unit 402 receives the received wave, which is the transmitted wave, reflected back by the object. The detection processing unit 429 detects information related to the object based on the information obtained as a result of transmitting and receiving the transmitted and received waves.

[0117] According to the above structure, it is possible to encode two or more combinations of multiple waves that are respectively modulated by multiple linear frequency modulation signals that vary in different frequency patterns, in a manner that includes appropriate identification information, and then transmit the transmitted wave. Therefore, the recognizability of the transmitted wave can be improved.

[0118] More specifically, in the first embodiment, the plurality of linear frequency modulated signals include a first linear frequency modulated signal whose frequency increases monotonically (refer to...). Figure 5 ), and a second linear frequency modulated signal whose frequency decreases monotonically (refer to Figure 6 Based on this structure, the recognizability of the transmitted wave can be easily improved using two linear frequency modulated signals with simple waveforms.

[0119] Furthermore, in the first embodiment, the object detection device 200 also includes a correlation processing unit 426 that acquires a correlation value representing the similarity between the transmitted wave and the received wave. Moreover, the detection processing unit 429 detects information related to the object based on a comparison result between the correlation value and a threshold. With this structure, information related to the object can be detected with high precision using the correlation value.

[0120] Furthermore, in the first embodiment, the detection processing unit 429 detects the distance to the object based on the difference between the time the transmitted wave is emitted and the time the received wave is received, thus providing information related to the object. With this structure, useful information such as the distance to the object can be obtained as object-related information.

[0121] <Second Implementation Method>

[0122] In the first embodiment described above, the carrier is modulated using a modulation mode based on frequency modulation of multiple linear frequency modulated signals, thereby improving the recognizability of the transmitted wave. However, as a second embodiment, a structure is also considered that uses frequency modulation based on a single linear frequency modulated signal and a modulation mode that utilizes phase modulation to modulate the carrier, thereby improving the recognizability of the transmitted wave.

[0123] Furthermore, the hardware structure and functional structure of the object detection system in the second embodiment are basically the same as those in the first embodiment described above. However, in the second embodiment, the modulation mode determination unit 413a (refer to...) Figure 4 The modulation mode of the carrier is determined using a method different from the first embodiment described above.

[0124] Figure 9 This is an illustrative and schematic diagram showing an example of the modulation method of the second embodiment.

[0125] like Figure 9 As shown, in the second embodiment, frequency modulation of a single linear frequency modulated signal that varies in a predetermined pattern based on frequency is implemented, and two or more combinations of multiple waves that are phase modulated in a manner that assigns mutually different phases are generated to produce a transmitted wave. Furthermore, each of the multiple waves mentioned here corresponds to... Figure 5 The carrier wave during period T is shown.

[0126] For example, in Figure 9 In the example shown, the third wave is frequency-modulated based on a first linear frequency modulated signal that monotonically increases during period T, and phase-modulated by allocating a phase "π". The third wave is assigned a code of bit "0". The fourth wave is frequency-modulated based on the first linear frequency modulated signal, and phase-modulated by allocating a phase "0". The fourth wave is assigned a code of bit "1". In this case, the transmitted wave, for example, is encoded with identification information consisting of a bit string such as "1101", as shown below. Figure 10 The modulation mode shown is generated by modulating the carrier wave.

[0127] Figure 10 This is an illustrative and schematic diagram showing an example of a modulation pattern corresponding to the identification information of the second embodiment.

[0128] like Figure 10 As shown, in the second embodiment, the transmitted wave encoded in a manner that includes identification information consisting of a bit string such as "1101" is constructed by combining the above-mentioned fourth wave with phase "0", the above-mentioned fourth wave with phase "0", the above-mentioned third wave with phase "π", and the above-mentioned fourth wave with phase "0" in this order.

[0129] Therefore, in the second embodiment, when the modulation mode determination unit 413a determines the code of a bit string such as "1101" as the identification information to be assigned to the transmitted wave, it determines the mode of the carrier as the combination of frequency modulation based on the first linear frequency modulation signal and phase modulation with phase "0" allocated, the combination of frequency modulation based on the first linear frequency modulation signal and phase modulation with phase "0" allocated, the combination of frequency modulation based on the first linear frequency modulation signal and phase modulation with phase "π" allocated, and the combination of frequency modulation based on the first linear frequency modulation signal and phase modulation with phase "0" allocated.

[0130] As explained above, the object detection system of the second embodiment has essentially the same structure as the first embodiment described above. However, the second embodiment differs from the first embodiment in that it transmits a transmitted wave encoded based on two or more combinations of multiple waves that have undergone frequency modulation of a single linear frequency modulated signal that varies in a predetermined pattern based on frequency, and phase modulation of multiple waves that have been assigned mutually different phases.

[0131] According to the above structure, based on frequency modulation of a single linear frequency modulated signal that varies in a predetermined pattern according to frequency, and phase modulation of multiple waves that are assigned mutually different phases, two or more combinations can be transmitted based on encoding in a manner containing appropriate identification information. Therefore, according to the second embodiment, similar to the first embodiment described above, the identifiability of the transmitted wave can also be improved.

[0132] Furthermore, the other effects of the second embodiment are the same as those of the first embodiment described above.

[0133] <Variation Example>

[0134] Furthermore, although the technology of the present invention is applied to structures that detect information related to objects by transmitting and receiving ultrasonic waves in the two embodiments described above, the technology of the present invention can also be applied to structures that detect information related to objects by transmitting and receiving waves other than ultrasonic waves, such as sound waves, millimeter waves, or electromagnetic waves.

[0135] Furthermore, although the two embodiments described above illustrate a structure that detects the distance to an object as information related to the object, the technology of the present invention can also be applied to a structure that detects only the presence or absence of an object as information related to the object.

[0136] Furthermore, while the first embodiment described above illustrates a technique for generating a transmission wave using two or more combinations of two waves (a first wave and a second wave) based on frequency modulation of two linear frequency modulated signals, the present invention also includes a technique for performing frequency modulation using three or more linear frequency modulated signals whose frequencies vary in mutually different patterns. Additionally, the present invention further includes a technique for generating a transmission wave using a single wave that is frequency modulated based on multiple linear frequency modulated signals.

[0137] Similarly, in the second embodiment described above, a technique for generating a transmission wave was illustrated by combining two or more combinations of two waves (a third wave and a fourth wave) that are frequency-modulated based on a single linear frequency modulated signal and whose phase modulation is performed by allocating two different phases to each other. However, the technique of the present invention also includes a technique for generating a transmission wave by combining two or more combinations of three or more waves that are frequency-modulated based on a single linear frequency modulated signal and whose phase modulation is performed by allocating three or more different phases to each other. Furthermore, the technique of the present invention also includes a technique for generating a transmission wave by using a single wave of multiple waves that are frequency-modulated based on a single linear frequency modulated signal and whose phase modulation is performed by allocating different phases to each other.

[0138] Furthermore, the technology of this invention can also be applied to the following: Figure 11 The technology shown combines the two embodiments described above.

[0139] Figure 11 This is an exemplary and schematic diagram illustrating a modulation method of a variant.

[0140] like Figure 11 As shown, in this variant, a transmitted wave is generated by combining one or more of a plurality of waves that are frequency-modulated based on a plurality of linear frequency modulated signals, in the same manner as the first embodiment described above, and by phase-modulating the waves in the same manner as the second embodiment described above, with each wave having a different phase. Furthermore, each of the plurality of waves mentioned here corresponds to... Figure 5 as well as Figure 6 The carrier wave during period T is shown.

[0141] For example, in Figure 11 In the example shown, the fifth wave was frequency-modulated based on a second linear frequency modulated signal that monotonically decreases during period T, and phase-modulated by assigning a phase "π". The fifth wave was assigned the code of a bit string "00". Similarly, the sixth wave was frequency-modulated based on the second linear frequency modulated signal, and phase-modulated by assigning a phase "0". The sixth wave was assigned the code of a bit string "01".

[0142] In addition, Figure 11 In the example shown, the seventh wave is frequency-modulated based on a first linear frequency modulated signal that monotonically increases during period T, and phase-modulated by assigning a phase “π”, thus assigning the seventh wave the code of a bit string “10”. Similarly, the eighth wave is frequency-modulated based on the first linear frequency modulated signal, and phase-modulated by assigning a phase “0”, thus assigning the eighth wave the code of a bit string “11”.

[0143] according to Figure 11 The variant shown employs both frequency modulation-based coding and phase modulation-based coding, thereby increasing the number of codes that can be represented and thus further improving the recognizability of the transmitted wave.

[0144] While the embodiments and modifications of the present invention have been described above, they are merely examples and are not intended to limit the scope of the invention. The new embodiments and modifications described above can be implemented in various forms, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. The above embodiments and modifications are included within the scope and spirit of the invention, and are included within the scope of the invention as described in the claims and its equivalents.

Claims

1. An object detection system, comprising multiple object detection devices, characterized in that, Each of the plurality of object detection devices includes: The transmitting unit transmits an ultrasonic wave, which is encoded based on identification information consisting of consecutive bit strings of two-valued bits, from multiple waves that have been frequency modulated, respectively, and is different from that of the other object detection devices. The frequency modulation is based on two linear frequency modulated signals whose frequencies vary in mutually different modes. The receiving unit receives the transmitted wave as a reflection of the object; as well as The detection processing unit detects information related to the object based on information obtained as a result of transmitting and receiving the transmitted and received waves. The two linear frequency modulated signals include: a first linear frequency modulated signal whose frequency increases monotonically, and a second linear frequency modulated signal whose frequency decreases monotonically. The transmitting unit selectively allocates either the first linear frequency modulated signal or the second linear frequency modulated signal according to the values ​​of each bit in the bit string constituting the identification information, thereby encoding the transmitted wave.

2. The object detection system according to claim 1, characterized in that, The transmitting unit transmits, approximately simultaneously with the other object detection devices, a transmitted wave encoded based on one or more combinations of a plurality of waves that are different from those of the other object detection devices, wherein the frequency modulation is based on the two linear frequency modulated signals and the phase modulation is performed in a manner that assigns mutually different phases.

3. The object detection system according to claim 1 or 2, characterized in that, The object detection system also includes a correlation processing unit, which obtains a correlation value representing the similarity between the transmitted wave and the received wave. The detection processing unit detects information related to the object based on the comparison result between the correlation value and the threshold.

4. The object detection system according to claim 1 or 2, characterized in that, The detection processing unit detects the distance to the object based on the difference between the time when the transmitted wave is transmitted and the time when the received wave is received, and uses this distance as information related to the object.

5. An object detection device, characterized in that, have: The transmitting unit transmits a transmission wave approximately simultaneously with other object detection devices. This wave is encoded based on identification information that is different from that of the other object detection devices and corresponds to a continuous bit string consisting of two-valued bits, which is frequency-modulated based on two linear frequency-modulated signals whose frequencies vary in mutually different patterns. The receiving unit receives the transmitted wave as a reflection of the object; as well as The detection processing unit detects information related to the object based on information obtained as a result of transmitting and receiving the transmitted and received waves. The two linear frequency modulated signals include: a first linear frequency modulated signal whose frequency increases monotonically, and a second linear frequency modulated signal whose frequency decreases monotonically. The transmitting unit selectively allocates either the first linear frequency modulated signal or the second linear frequency modulated signal according to the values ​​of each bit in the bit string constituting the identification information, thereby encoding the transmitted wave.

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