Object detection device

Abstract

To provide an object detection device with further improved code identification performance.SOLUTION: A drive control unit (71) sets a frequency modulation mode within a predetermined frequency band in a drive signal. The drive signal is a signal for driving a transmission unit (40A) to transmit, toward the outside, ultrasonic transmission waves encoded by frequency modulation. N frequency bands are set for frequency change patterns of the drive signal, and there are "N×2" kinds of combinations of signals whose frequencies rise and fall with time in each band. A detection unit (73) detects an object around a moving body based on a reception signal corresponding to a result received by a reception unit (40B) of a reception wave including a reflected wave resulting from the transmission wave reflected in the object.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an object detection device that is mounted on a moving body and configured to detect objects around the moving body. [Background technology]

[0002] When detecting an object such as an obstacle using an ultrasonic sensor, there is a problem that a signal emitted by another ultrasonic sensor mounted on the own vehicle or a signal emitted by another ultrasonic sensor mounted on another vehicle around the own vehicle is mistakenly detected as the own signal. In response to this problem, Patent Document 1 proposes a technique using multi-bit encoding by the FSK method or the PSK method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2013-538344 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the technology disclosed in Patent Document 1, an ultrasonic sensor can distinguish whether a received wave is a reflected wave of an ultrasonic wave that it transmitted itself. However, when the ultrasonic sensor faces a wall or a pole, the reflected wave from the base and the reflected wave from the front overlap, even if the reflected wave is an ultrasonic wave that it transmitted itself.

[0005] The inventors have found that in obstacle detection using an ultrasonic sensor, even if encoding is used, in a scene where reflected waves overlap, it is difficult to identify the code due to interference between the reflected waves. The present invention has been made in consideration of the above-mentioned circumstances. That is, the present invention provides, for example, an object detection device with improved code identification performance. [Means for solving the problem]

[0006] The object detection device (3) described in claim 1 is configured to detect an object (B) around a moving body (C) when mounted on the moving body. This object detection device is a drive control unit (71) that sets a frequency modulation mode within a predetermined frequency band in a drive signal that drives a transmission unit (40A) to transmit to the outside a transmission wave that is an ultrasonic wave encoded by frequency modulation; a detection unit (73) that detects the object based on a reception signal corresponding to a reception result by a receiving unit (40B) of a reception wave including a reflected wave of the transmission wave by the object; Equipped with the detection unit has a determination unit (74) that determines a code included in the received wave based on a match between a reference signal corresponding to the drive signal and the received signal; The drive control unit selects and sets the code to be assigned to the drive signal from a plurality of types of codes including at least a first code characterized by a frequency modulation mode in which the frequency increases over time in a first frequency band, a second code characterized by a frequency modulation mode in which the frequency increases over time in a second frequency band different from the first frequency band, a third code characterized by a frequency modulation mode in which the frequency decreases over time in a third frequency band, and a fourth code characterized by a frequency modulation mode in which the frequency decreases over time in a fourth frequency band different from the third frequency band. At the same time, the frequency band and / or the number of pulses in the drive signal are increased as the code corresponding to the frequency band is farther away from the center frequency of the transmission unit. Consists of an upper limit frequency of the first frequency band is higher than an upper limit frequency of the second frequency band; a lower limit frequency of the first frequency band is higher than a lower limit frequency of the second frequency band, an upper limit frequency of the third frequency band is higher than an upper limit frequency of the fourth frequency band; The lower limit frequency of the third frequency band is higher than the lower limit frequency of the fourth frequency band. The object detection device (3) described in claim 3 is configured to detect an object (B) around a moving body (C) when mounted on the moving body. This object detection device is a drive control unit (71) that sets a frequency modulation mode within a predetermined frequency band in a drive signal that drives a transmission unit (40A) to transmit to the outside a transmission wave that is an ultrasonic wave encoded by frequency modulation; a detection unit (73) that detects the object based on a reception signal corresponding to a reception result by a receiving unit (40B) of a reception wave including a reflected wave of the transmission wave by the object; Equipped with the detection unit has a determination unit (74) that determines a code included in the received wave based on a match between a reference signal corresponding to the drive signal and the received signal; The drive control unit is a code to be assigned to the drive signal is selected and set from a plurality of types of codes including at least a first code characterized by a frequency modulation mode in which the frequency increases over time in a first frequency band, a second code characterized by a frequency modulation mode in which the frequency increases over time in a second frequency band different from the first frequency band, a third code characterized by a frequency modulation mode in which the frequency decreases over time in a third frequency band, and a fourth code characterized by a frequency modulation mode in which the frequency decreases over time in a fourth frequency band different from the third frequency band; When the start frequency of the drive signal is close to the center frequency of the transmitter, the start frequency is set to the opposite side of the center frequency of the transmitter from the end frequency of the drive signal; When the end frequency of the drive signal is close to the center frequency of the transmitter, the end frequency is configured to be on the opposite side of the center frequency of the transmitter from the start frequency of the drive signal, an upper limit frequency of the first frequency band is higher than an upper limit frequency of the second frequency band; a lower limit frequency of the first frequency band is higher than a lower limit frequency of the second frequency band, an upper limit frequency of the third frequency band is higher than an upper limit frequency of the fourth frequency band; The lower limit frequency of the third frequency band is higher than the lower limit frequency of the fourth frequency band. The object detection device (3) recited in claim 6 is configured to detect an object (B) around a moving body (C) when mounted on the moving body. This object detection device is a drive control unit (71) that sets a frequency modulation mode within a predetermined frequency band in a drive signal that drives a transmission unit (40A) to transmit to the outside a transmission wave that is an ultrasonic wave encoded by frequency modulation; a correction unit (72) that corrects a reference signal corresponding to the drive signal in accordance with a moving speed of the moving body; a detection unit (73) that detects the object based on a reception signal corresponding to a reception result by a receiving unit (40B) of a reception wave including a reflected wave of the transmission wave by the object; Equipped with the detection unit has a determination unit (74) that determines a code included in the received wave based on a match between the reference signal and the received signal; the drive control unit is configured to select and set, as a code to be assigned to the drive signal, any one of a plurality of types of codes including at least a first code characterized by a frequency modulation mode in which a frequency increases over time within a first frequency band, a second code characterized by a frequency modulation mode in which a frequency increases over time within a second frequency band different from the first frequency band, a third code characterized by a frequency modulation mode in which a frequency decreases over time within a third frequency band, and a fourth code characterized by a frequency modulation mode in which a frequency decreases over time within a fourth frequency band different from the third frequency band; an upper limit frequency of the first frequency band is higher than an upper limit frequency of the second frequency band; a lower limit frequency of the first frequency band is higher than a lower limit frequency of the second frequency band, an upper limit frequency of the third frequency band is higher than an upper limit frequency of the fourth frequency band; The lower limit frequency of the third frequency band is higher than the lower limit frequency of the fourth frequency band. The object detection device (3) recited in claim 9 is configured to detect an object (B) around a moving body (C) when mounted on the moving body. This object detection device is a drive control unit (71) that sets a frequency modulation mode within a predetermined frequency band in a drive signal that drives a transmission unit (40A) to transmit to the outside a transmission wave that is an ultrasonic wave encoded by frequency modulation; a detection unit (73) that detects the object based on a reception signal corresponding to a reception result by a receiving unit (40B) of a reception wave including a reflected wave of the transmission wave by the object; Equipped with the detection unit has a determination unit (74) that determines a code included in the received wave based on a match between a reference signal corresponding to the drive signal and the received signal; the drive control unit is configured to select and set, as a code to be assigned to the drive signal, any one of a plurality of types of codes including at least a first code characterized by a frequency modulation mode in which a frequency increases over time within a first frequency band, a second code characterized by a frequency modulation mode in which a frequency increases over time within a second frequency band different from the first frequency band, a third code characterized by a frequency modulation mode in which a frequency decreases over time within a third frequency band, and a fourth code characterized by a frequency modulation mode in which a frequency decreases over time within a fourth frequency band different from the third frequency band; an upper limit frequency of the first frequency band is higher than an upper limit frequency of the second frequency band; a lower limit frequency of the first frequency band is higher than a lower limit frequency of the second frequency band, an upper limit frequency of the third frequency band is higher than an upper limit frequency of the fourth frequency band; a lower limit frequency of the third frequency band is higher than a lower limit frequency of the fourth frequency band, A plurality of the transmitting units are arranged in an arrangement direction that intersects with the direction of travel of the moving body, and among the plurality of the transmitting units, the transmitting unit that is currently driven by the drive control unit is designated as the self transmitting unit, and the other transmitting units different from the self transmitting unit are designated as other transmitting units.The drive control unit assigns a code different from that of the other transmitting units to the drive signal so that the frequency changes in a different direction from that of the adjacent other transmitting units. The object detection device (3) recited in claim 12 is configured to detect an object (B) around a moving body (C) when mounted on the moving body. This object detection device is a drive control unit (71) that sets a frequency modulation mode within a predetermined frequency band in a drive signal that drives a transmission unit (40A) to transmit to the outside a transmission wave that is an ultrasonic wave encoded by frequency modulation; a detection unit (73) that detects the object based on a reception signal corresponding to a reception result by a receiving unit (40B) of a reception wave including a reflected wave of the transmission wave by the object; Equipped with the detection unit has a determination unit (74) that determines a code included in the received wave based on a match between a reference signal corresponding to the drive signal and the received signal; the drive control unit is configured to select and set, as a code to be assigned to the drive signal, any one of a plurality of types of codes including at least a first code characterized by a frequency modulation mode in which a frequency increases over time within a first frequency band, a second code characterized by a frequency modulation mode in which a frequency increases over time within a second frequency band different from the first frequency band, a third code characterized by a frequency modulation mode in which a frequency decreases over time within a third frequency band, and a fourth code characterized by a frequency modulation mode in which a frequency decreases over time within a fourth frequency band different from the third frequency band; an upper limit frequency of the first frequency band is higher than an upper limit frequency of the second frequency band; a lower limit frequency of the first frequency band is higher than a lower limit frequency of the second frequency band, an upper limit frequency of the third frequency band is higher than an upper limit frequency of the fourth frequency band; a lower limit frequency of the third frequency band is higher than a lower limit frequency of the fourth frequency band, K transmitters are arranged in an arrangement direction intersecting with the traveling direction of the moving body, and among the plurality of transmitters, the transmitter currently driven by the drive control unit is defined as a local transmitter, and the other transmitters different from the local transmitter are defined as other transmitters. When a total of K transmissions in which each of the K transmitters transmits the transmission wave once in turn is defined as one cycle, the drive control unit assigns a different code to the drive signal that drives the local transmitter for each cycle, When there are M types of codes that can be assigned to the drive signal, the drive control unit assigns M types of codes to the drive signal that drives the own transmission unit in M ​​cycles.

[0007] In addition, in each section of the application documents, each element may be given a reference number in parentheses. However, such a reference number merely indicates an example of the correspondence between the element and the specific means described in the embodiment described later. Therefore, the present invention is not limited in any way by the description of the reference numbers above. [Brief description of the drawings]

[0008] [Figure 1] 1 is a plan view showing a schematic configuration of a vehicle equipped with an in-vehicle system capable of detecting surrounding objects. [Diagram 2] 2 is a block diagram showing a schematic functional configuration of the in-vehicle system shown in FIG. 1. [Diagram 3] 3 is a time chart showing frequency characteristics of a specific example of a drive signal that can be output by the drive signal generating unit shown in FIG. 2. [Figure 4] 4 is a vehicle plan view illustrating an example of driving a plurality of ultrasonic sensors using the driving signals illustrated in FIG. 3. FIG. [Diagram 5] 4 is a graph showing frequency characteristics of a received signal corresponding to the drive signal shown in FIG. 3. [Figure 6] 4 is a graph showing amplitude characteristics of a received signal corresponding to the drive signal shown in FIG. 3. [Figure 7] 11 is a time chart showing frequency characteristics of a drive signal in a comparative example. [Figure 8]8 is a graph showing frequency characteristics and amplitude characteristics of a received signal corresponding to the drive signal of the comparative example shown in FIG. 7. [Figure 9] 8 is a graph showing frequency characteristics and amplitude characteristics of a received signal corresponding to the drive signal of the comparative example shown in FIG. 7. [Figure 10] 3 is a graph showing the effect of pulse compression processing by the reception signal processing unit shown in FIG. 2. [Figure 11] 3 is a time chart showing an overview of Doppler shift correction by a correction unit shown in FIG. 2. [Figure 12] 3 is a plan view of a vehicle illustrating an overview of Doppler shift correction performed by a correction unit shown in FIG. 2. [Figure 13] 3 is a time chart showing frequency characteristics of another specific example of a drive signal that can be output by the drive signal generating unit shown in FIG. 2. [Figure 14] 14 is a graph showing frequency characteristics of a received signal corresponding to the drive signal shown in FIG. 13. [Figure 15] 10 is a time chart showing frequency characteristics of still another specific example of a drive signal that can be output by the drive signal generating section shown in FIG. 2. [Figure 16] 16 is a graph showing frequency characteristics of a received signal corresponding to the drive signal shown in FIG. 15. [Figure 17] 10 is a time chart showing frequency characteristics of still another specific example of a drive signal that can be output by the drive signal generating section shown in FIG. 2. [Figure 18] 10 is a time chart showing frequency characteristics of still another specific example of a drive signal that can be output by the drive signal generating section shown in FIG. 2. [Figure 19A] 10 is a vehicle plan view illustrating another driving example in which each of a plurality of ultrasonic sensors is driven using the driving signals illustrated in FIG. 3 and the like. FIG. [Figure 19B] 10 is a vehicle plan view illustrating another driving example in which each of a plurality of ultrasonic sensors is driven using the driving signals illustrated in FIG. 3 and the like. FIG. [Figure 19C]10 is a vehicle plan view illustrating another driving example in which each of a plurality of ultrasonic sensors is driven using the driving signals illustrated in FIG. 3 and the like. FIG. [Figure 19D] 10 is a vehicle plan view illustrating another driving example in which each of a plurality of ultrasonic sensors is driven using the driving signals illustrated in FIG. 3 and the like. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that various modified examples applicable to one embodiment may be hindered from understanding the embodiment if they are inserted in the middle of a series of explanations related to the embodiment. For this reason, the modified examples are described together after the explanation of the embodiment.

[0010] (Overall system configuration) 1, the in-vehicle system 1 is mounted on a vehicle C as a moving body. The vehicle C is a so-called four-wheeled automobile, and has a box-shaped body C1 formed in a substantially rectangular shape in a plan view. The shape of each part of the vehicle C in a "plan view" refers to the shape of that part when the vehicle C is stably placed on a horizontal surface so as to be able to run, and the part is viewed from the line of sight in the same direction as the direction of gravity. The vehicle C equipped with the in-vehicle system 1 according to this embodiment is hereinafter referred to as the "own vehicle."

[0011] Hereinafter, a virtual straight line that passes through the center of the host vehicle in the vehicle width direction in a plan view and is parallel to the vehicle overall length direction of the host vehicle is referred to as the vehicle center line LC. The vehicle overall length direction is a direction perpendicular to the vehicle width direction and perpendicular to the vehicle height direction. The vehicle height direction is a direction that defines the vehicle height of the host vehicle and is a direction parallel to the direction of gravity when the host vehicle is stably placed on a horizontal surface so that it can run. In addition, "front", "rear", "left", "right" and "up" are defined as shown by the arrows in FIG. 1. In other words, the vehicle overall length direction is synonymous with the front-rear direction. In addition, the vehicle width direction is synonymous with the left-right direction.

[0012] The in-vehicle system 1 includes an electronic control unit 2 and an ultrasonic sensor 3. The electronic control unit 2 is an in-vehicle microcomputer that may also be called an ECU, and includes a CPU, a ROM, a RAM, a non-volatile RAM, and the like, which are not shown. ECU stands for Electronic Control Unit. The non-volatile RAM is a storage device that allows information to be rewritten while the power is on, but holds information in a non-rewritable manner while the power is off, such as a flash ROM. The ROM, RAM, and non-volatile RAM are non-transient physical storage media. The electronic control unit 2 is adapted to be mounted inside a vehicle body C1.

[0013] The electronic control unit 2 is connected to the ultrasonic sensor 3 via an on-board information communication line so as to be able to transmit and receive information. In this embodiment, the vehicle is equipped with a plurality of ultrasonic sensors 3. The electronic control unit 2 is configured to read and execute a control program stored in a ROM or non-volatile RAM, thereby controlling the overall operation of the on-board system 1, including the timing of ultrasonic transmission and reception operations of each of the plurality of ultrasonic sensors 3. In other words, the on-board system 1 is configured to detect an object B around the vehicle based on the results of ultrasonic transmission and reception by the ultrasonic sensor 3 while mounted on the vehicle.

[0014] A first front sensor 3A, a second front sensor 3B, a third front sensor 3C, and a fourth front sensor 3D are attached to the front bumper of the vehicle, i.e., the bumper C2 on the front side of the vehicle body C1, as ultrasonic sensors 3. Similarly, a first rear sensor 3E, a second rear sensor 3F, a third rear sensor 3G, and a fourth rear sensor 3H are attached to the rear bumper of the vehicle, i.e., the bumper C2 on the rear side of the vehicle body C1, as ultrasonic sensors 3.

[0015] The first front sensor 3A is provided at the right end of the front bumper so as to transmit a transmission wave to the right front of the vehicle. The second front sensor 3B is disposed between the first front sensor 3A and the vehicle center line LC in the vehicle width direction so as to transmit a transmission wave to approximately the front of the vehicle. The third front sensor 3C is disposed at a position approximately symmetrical to the second front sensor 3B across the vehicle center line LC. The third front sensor 3C is disposed between the vehicle center line LC and the fourth front sensor 3D in the vehicle width direction so as to transmit a transmission wave to approximately the front of the vehicle. The fourth front sensor 3D is disposed at a position approximately symmetrical to the first front sensor 3A across the vehicle center line LC. The fourth front sensor 3D is provided at the left end of the front bumper so as to transmit a transmission wave to the left front of the vehicle.

[0016] The first rear sensor 3E is provided at the right end of the rear bumper so as to transmit a transmission wave to the right rear of the vehicle. The second rear sensor 3F is disposed between the first rear sensor 3E and the vehicle center line LC in the vehicle width direction so as to transmit a transmission wave to the approximately rear of the vehicle. The third rear sensor 3G is disposed at a position approximately symmetrical to the second rear sensor 3F across the vehicle center line LC. The third rear sensor 3G is disposed between the vehicle center line LC and the fourth rear sensor 3H in the vehicle width direction so as to transmit a transmission wave to the approximately rear of the vehicle. The fourth rear sensor 3H is disposed at a position approximately symmetrical to the first rear sensor 3E across the vehicle center line LC. The fourth rear sensor 3H is provided at the left end of the rear bumper so as to transmit a transmission wave to the left rear of the vehicle.

[0017] (Ultrasonic Sensor) Hereinafter, a schematic configuration of the ultrasonic sensor 3 will be described with reference to Fig. 2. In Fig. 2, for the sake of simplicity, only one of the multiple ultrasonic sensors 3 connected to the electronic control device 2 is shown, and the others are omitted.

[0018] The ultrasonic sensor 3 is configured to transmit a transmission wave, which is an ultrasonic wave encoded by frequency modulation, toward the outside of the vehicle. The ultrasonic sensor 3 is also configured to receive a reception wave including a reflected wave of the transmitted transmission wave by an object B, thereby detecting the object B present in the vicinity and acquiring the distance to the object B.

[0019] Specifically, the ultrasonic sensor 3 includes a transmitter / receiver 4, a drive signal generator 5, a received signal processor 6, and a sensor controller 7. In this embodiment, the transmitter / receiver 4, the drive signal generator 5, the received signal processor 6, and the sensor controller 7 are supported by a single sensor housing made of synthetic resin or the like.

[0020] In this embodiment, the ultrasonic sensor 3 includes only one transmitting / receiving unit 4, and is configured to perform a transmitting / receiving function by the transmitting / receiving unit 4. That is, the transmitting / receiving unit 4 has a function as a transmitting unit 40A that transmits a transmission wave to the outside, and a function as a receiving unit 40B that receives a received wave. Specifically, one transmitting / receiving unit 4 has one transducer 41. The transmitting unit 40A and the receiving unit 40B are configured to achieve the transmitting function and the receiving function, respectively, by using the common transducer 41.

[0021] The transducer 41 is configured to function as a transmitter that transmits a transmission wave to the outside and as a receiver that receives a reflected wave. The transducer 41 has a structure as a so-called resonant ultrasonic microphone with a built-in electro-mechanical energy conversion element such as a piezoelectric element. Specifically, the transducer 41 is formed by joining an electro-mechanical energy conversion element to a bottom plate of a casing having a substantially bottomed cylindrical shape. When the casing is mounted on the vehicle, it is inserted into a through hole C3 formed in a bumper C2, so that a transmitting / receiving surface 41a, which is the outer surface of the bottom plate constituting a diaphragm, faces the external space of the vehicle.

[0022] The transmitting / receiving unit 4 includes a transducer 41, a transmitting circuit 42, and a receiving circuit 43. That is, the transmitting unit 40A includes the transducer 41 and the transmitting circuit 42. The receiving unit 40B includes the transducer 41 and the receiving circuit 43. The transducer 41 is electrically connected to the transmitting circuit 42 and the receiving circuit 43.

[0023] The transmission circuit 42 is provided to drive the transducer 41 based on the input drive signal, thereby causing the transducer 41 to emit a transmission wave in the ultrasonic band. Specifically, the transmission circuit 42 has a digital / analog conversion circuit and the like. That is, the transmission circuit 42 is configured to perform processing such as digital / analog conversion on the drive signal output from the drive signal generation unit 5, and apply the AC voltage generated thereby to the transducer 41.

[0024] The receiving circuit 43 is provided to generate a receiving signal corresponding to the result of receiving the ultrasonic wave in the transducer 41, and to output the generated receiving signal to the receiving signal processing unit 6. Specifically, the receiving circuit 43 has an amplifier circuit, an analog / digital conversion circuit, and the like. That is, the receiving circuit 43 is configured to perform signal processing such as amplification and analog / digital conversion on the voltage signal input from the transducer 41, thereby generating and outputting a receiving signal corresponding to the frequency and amplitude of the received ultrasonic wave.

[0025] In this way, the transmitter / receiver 4 is configured to generate a reception signal according to the distance to the object B by transmitting a transmission wave and receiving a reflected wave of the transmission wave transmitted by the transducer 41 as a transmitter / receiver. The received wave when the transducer 41 as a transmitter / receiver receives a reflected wave of the transmission wave transmitted by itself is hereinafter referred to as a "regular wave". In contrast, the received wave caused by a transmission wave from another device is hereinafter referred to as an "irregular wave". The "other device" includes not only an ultrasonic sensor 3 mounted on another vehicle different from the own vehicle, but also another ultrasonic sensor 3 mounted on the own vehicle.

[0026] The drive signal generating unit 5 is provided to generate a drive signal for driving the transmitting unit 40A. The drive signal is a signal for driving the transmitting unit 40A to transmit a transmission wave from the transducer 41, and is, for example, a pulsed signal in the ultrasonic band. Specific examples of the drive signal will be described later. The drive signal generating unit 5 is also configured to output a reference signal corresponding to the drive signal to the received signal processing unit 6. The reference signal is a signal for comparison with the frequency characteristics in the received signal for code identification, and has frequency characteristics corresponding to the frequency characteristics of the drive signal.

[0027] The received signal processing unit 6 is configured to execute various signal processing including pulse compression processing on the received signal output from the receiving circuit 43, and to output a processing result signal generated by the signal processing to the sensor control unit 7. Specifically, the received signal processing unit 6 has a correlation filter (e.g., a matched filter) for calculating the correlation between the received signal and a reference signal.

[0028] The sensor control unit 7 is communicably connected to the electronic control unit 2 so as to cooperate with the electronic control unit 2 and control the operation of the ultrasonic sensor 3. That is, the sensor control unit 7 is configured to control the output of the drive signal from the drive signal generation unit 5 to the transmission unit 40A, and to detect the object B based on the processing result signal output from the received signal processing unit 6.

[0029] The sensor control unit 7 has a configuration as an in-vehicle microcomputer equipped with a CPU, ROM, RAM, non-volatile RAM, etc. (not shown), and is provided to read and execute a control program stored in the ROM or non-volatile RAM to control the operation of the ultrasonic sensor 3. Specifically, the sensor control unit 7 has a drive control unit 71, a correction unit 72, and a detection unit 73 as functional configurations realized on the in-vehicle microcomputer.

[0030] The drive control unit 71 is configured to control the emission state of the transmission wave from the transmitter 40A by outputting a control signal to the drive signal generation unit 5. The control signal is a signal for controlling the output characteristics of the drive signal output from the drive signal generation unit 5 to the transceiver unit 4, specifically, the output timing, frequency, number of pulses, etc. In other words, the drive control unit 71 is adapted to control the output timing, frequency, number of pulses, etc. of the drive signal generated and output by the drive signal generation unit 5. The frequency of the drive signal may be referred to as the "drive frequency" hereinafter.

[0031] In this embodiment, the drive control unit 71 is configured to set the frequency modulation mode of the drive signal within a predetermined frequency band. That is, the drive signal generation unit 5 is capable of selectively outputting one of a plurality of types of drive signals having different frequency bands and / or frequency modulation modes. Specific examples of the plurality of types of drive signals will be described later.

[0032] The correction unit 72 is configured to correct the reference signal (i.e., Doppler shift correction) in accordance with the moving speed of the host vehicle. Specifically, in this embodiment, the correction unit 72 corrects the reference signal in accordance with the moving speed of the host vehicle and the relative position of the object B with respect to the host vehicle. The correction of the reference signal by the correction unit 72 will be described in detail later.

[0033] The detection unit 73 is configured to detect the object B based on a reception signal corresponding to the reception result by the receiving unit 40B of the reception wave. Specifically, the detection unit 73 is configured to identify whether or not the reception signal corresponds to a normal wave based on the processing result signal output from the reception signal processing unit 6. Furthermore, when the reception signal is a normal wave, the detection unit 73 is configured to calculate the distance to the object B based on the propagation time.

[0034] The detection unit 73 has a determination unit 74 for identifying whether the received signal corresponds to a normal wave. The determination unit 74 is configured to determine the code included in the received wave based on the coincidence between a reference signal corresponding to the drive signal and the received signal. Specifically, the determination unit 74 is adapted to determine the code based on a processing result signal which is a calculation result of the coincidence between the reference signal corrected by the correction unit 72 and the received signal.

[0035] (Operation overview) An outline of the operation of the configuration of this embodiment will be described below with reference to Figures 1 to 4. In the following description, the device configuration, control method, and control program according to this embodiment may be simply referred to as "this embodiment."

[0036] 2, the drive control unit 71 outputs a control signal to the drive signal generating unit 5. Then, the drive signal generating unit 5 generates a drive signal based on the control signal, and outputs the generated drive signal to the transmitting unit 40A. The transmitting unit 40A is driven by the drive signal. That is, the transmitting circuit 42 excites the transducer 41 based on the input drive signal. As a result, a transmission wave is transmitted from the transducer 41 functioning as a transmitter to the outside of the vehicle. The transmission wave is encoded by frequency modulation based on the drive signal.

[0037] The drive control unit 71 sets the code in the drive signal, that is, the frequency modulation mode within a predetermined frequency band. Specifically, the drive control unit 71 selects one of a plurality of types of codes as the code to be added to the drive signal. When transmitting a single transmission wave, it is possible to set a code string of multiple bits in which a plurality of codes are arranged.

[0038] (Example 1) FIG. 3 shows a specific example of the drive signal. In this example, the drive signal generating section 5 can selectively output four types of drive signals, the first drive signal DS1 to the fourth drive signal DS4. "Selectively outputtable" means that in one drive signal generating section 5, while any one of the first drive signal DS1 to the fourth drive signal DS4 is being output, the other three are not output. Specifically, for example, in one drive signal generating section 5, while the first drive signal DS1 is being output, the second drive signal DS2 to the fourth drive signal DS4 are not output from the drive signal generating section 5. However, after the first drive signal DS1 is output, the drive signal generating section 5 can output any one of the first drive signal DS1 to the fourth drive signal DS4 again. The first drive signal DS1 to the fourth drive signal DS4 have different frequency bands and / or frequency modulation modes. The drive control section 71 controls which of the first drive signal DS1 to the fourth drive signal DS4 the drive signal generating section 5 outputs.

[0039] In the figure, the microphone center frequency fc is the center of a predetermined design transmission / reception frequency band fr0 in the transducer 41 as a transmitter / receiver, and is approximately the same as or close to the resonant frequency. The design transmission / reception frequency band fr0 is a range in which the sensitivity is 0 to Sb [dB] when the sensitivity at the microphone center frequency fc is 0 [dB]. In other words, the design transmission / reception frequency band fr0, which is a frequency range in which the transmitter 40A can transmit and receive signals satisfactorily, is a frequency band between the design upper limit frequency fu and the design lower limit frequency fd in which the sensitivity is 0 to Sb [dB]. Sb is typically, for example, -3 [dB]. The sensitivity is the sensitivity when the transducer 41 is used as a receiver. The microphone center frequency fc may also be called the "design center frequency".

[0040] The first frequency band fr1 is a frequency band corresponding to the first drive signal DS1. That is, the first drive signal DS1 has a frequency modulation mode in which the frequency changes within the first frequency band fr1 over time. Similarly, the second frequency band fr2 is a frequency band corresponding to the second drive signal DS2. The third frequency band fr3 is a frequency band corresponding to the third drive signal DS3. The fourth frequency band fr4 is a frequency band corresponding to the fourth drive signal DS4. In the figure, the center frequency of each of the first frequency band fr1 to the fourth frequency band fr4 is indicated by a circle. The center frequency of each of the first frequency band fr1 to the fourth frequency band fr4 is the median value between the upper limit frequency and the lower limit frequency of each frequency band.

[0041] As shown in Fig. 3, the center frequency of the first frequency band fr1 is higher than the microphone center frequency fc. In this example, the lower limit frequency of the first frequency band fr1 is the microphone center frequency fc. The upper limit frequency of the first frequency band fr1 is the design upper limit frequency fu. In other words, the first frequency band fr1 is the higher frequency band when the design transmission / reception frequency band fr0 is divided into two by the microphone center frequency fc.

[0042] The first drive signal DS1 corresponds to the symbol UH. The symbol UH is characterized by a frequency modulation mode in which the frequency increases over time within the first frequency band fr1. Specifically, the symbol UH corresponds to an "up chirp" in which the drive frequency increases linearly from the lower limit frequency to the upper limit frequency in the first frequency band fr1. In the symbol UH, "U" indicates "up chirp" and "H" indicates a frequency band higher than the microphone center frequency fc.

[0043] The center frequency of the second frequency band fr2 is lower than the microphone center frequency fc. The upper limit frequency of the second frequency band fr2 is lower than the upper limit frequency of the first frequency band fr1. The lower limit frequency of the second frequency band fr2 is lower than the lower limit frequency of the first frequency band fr1. In other words, the second frequency band fr2 is in a relationship in which the first frequency band fr1 is offset to the lower frequency side.

[0044] In this example, the lower limit frequency of the second frequency band fr2 is the design lower limit frequency fd. The upper limit frequency of the second frequency band fr2 is the microphone center frequency fc. That is, the second frequency band fr2 is the lower frequency band when the design transmission / reception frequency band fr0 is divided into two by the microphone center frequency fc. In other words, the first frequency band fr1 and the second frequency band fr2 are obtained by dividing the design transmission / reception frequency band fr0 into two by the microphone center frequency fc.

[0045] The second drive signal DS2 corresponds to the symbol UL. The symbol UL is characterized by a frequency modulation mode in which the frequency increases over time in a second frequency band fr2 different from the first frequency band fr1. Specifically, the symbol UL corresponds to an "up chirp" in which the drive frequency increases linearly from the lower limit frequency to the upper limit frequency in the second frequency band fr2. In the symbol UL, "U" indicates "up chirp" and "L" indicates a frequency band lower than the microphone center frequency fc.

[0046] The center frequency of the third frequency band fr3 is higher than the microphone center frequency fc. In this example, the lower limit frequency of the third frequency band fr3 is the microphone center frequency fc. Moreover, the upper limit frequency of the third frequency band fr3 is the design upper limit frequency fu. That is, the third frequency band fr3 is the higher frequency band when the design transmission / reception frequency band fr0 is divided into two by the microphone center frequency fc. Furthermore, the third frequency band fr3 is the same as the first frequency band fr1. That is, the first frequency band fr1 and the third frequency band fr3 have the same center frequency and frequency bandwidth.

[0047] The third drive signal DS3 corresponds to the symbol DH. The symbol DH is characterized by a frequency modulation mode in which the frequency decreases over time within the third frequency band fr3. Specifically, the symbol DH corresponds to a "down chirp" in which the drive frequency increases linearly from the upper limit frequency to the lower limit frequency in the third frequency band fr3. In the symbol DH, "D" indicates "down chirp" and "H" indicates a frequency band higher than the microphone center frequency fc.

[0048] The center frequency of the fourth frequency band fr4 is lower than the microphone center frequency fc. The upper limit frequency of the fourth frequency band fr4 is lower than the upper limit frequency of the third frequency band fr3. The lower limit frequency of the fourth frequency band fr4 is lower than the lower limit frequency of the third frequency band fr3. In other words, the fourth frequency band fr4 is in a relationship in which the third frequency band fr3 is offset to the lower frequency side.

[0049] In this example, the lower limit frequency of the fourth frequency band fr4 is the design lower limit frequency fd. Moreover, the upper limit frequency of the fourth frequency band fr4 is the microphone center frequency fc. That is, the fourth frequency band fr4 is the lower frequency band when the design transmission / reception frequency band fr0 is divided into two by the microphone center frequency fc. In other words, the third frequency band fr3 and the fourth frequency band fr4 are obtained by dividing the design transmission / reception frequency band fr0 into two by the microphone center frequency fc. Moreover, the fourth frequency band fr4 is the same as the second frequency band fr2.

[0050] The fourth drive signal DS4 corresponds to the symbol DL. The symbol DL is characterized by a frequency modulation mode in which the frequency decreases over time in a fourth frequency band fr4 different from the third frequency band fr3. Specifically, the symbol DL corresponds to a "down chirp" in which the drive frequency increases linearly from the upper limit frequency to the lower limit frequency in the fourth frequency band fr4. In the symbol DL, "D" indicates "down chirp" and "L" indicates a frequency band lower than the microphone center frequency fc.

[0051] In this way, the drive control unit 71 selects and sets the code to be assigned to the drive signal from among multiple types of codes, UH, UL, DH, and DL. As a result, the code to be set to a specific bit is selected from UH, UL, DH, and DL. Specifically, for example, a multi-bit code sequence of "UH, DL, UL, ..." can be generated. Then, a transmission wave that has been chirp frequency modulated in accordance with the code or code sequence set by the drive control unit 71 is transmitted from the transmission / reception unit 4.

[0052] Fig. 4 shows a state in which the host vehicle detects an obstacle in front of the host vehicle while traveling forward. As shown in Fig. 4, when mounted on the vehicle, the first front sensor 3A to the fourth front sensor 3D are arranged in a vehicle width direction that intersects with the traveling direction of the host vehicle.

[0053] Here, the "own sensor" and the "other sensor" of the multiple ultrasonic sensors 3 arranged in the vehicle width direction, that is, the first front sensor 3A to the fourth front sensor 3D, are defined as follows. The "own sensor" is one of the first front sensor 3A to the fourth front sensor 3D that is of interest. The "other sensor" is one of the first front sensor 3A to the fourth front sensor 3D that is different from the own sensor. Specifically, for example, when explaining the operation of the second front sensor 3B, the second front sensor 3B is the "own sensor", and the first front sensor 3A, the third front sensor 3C, and the fourth front sensor 3D are the "other sensors". The transducer 41 provided in the own sensor corresponds to the "own transmission unit", and the transducer 41 provided in the other sensor corresponds to the "other transmission unit". As is clear from the above definition, the "other sensor" is also mounted on the own vehicle, like the "own sensor". In contrast, the ultrasonic sensor 3 mounted on the other vehicle different from the own vehicle is hereinafter referred to as the "other vehicle mounted sensor" to distinguish it from the "other sensor". The above-mentioned "other device" refers collectively to "other sensors" and "sensors mounted on other vehicles."

[0054] In this embodiment, the drive control unit 71 in each of the first front sensor 3A to the fourth front sensor 3D cooperates with the electronic control unit 2 to give a code different from that of the other sensors to the drive signal of the sensor itself so that the frequency changes in a different direction from that of the other adjacent sensors. That is, for example, as shown in FIG. 4, the codes of the first front sensor 3A to the fourth front sensor 3D are DH, UH, DL, and UL, respectively. As a result, the sensor itself and the other adjacent sensors are a combination of up-chirp and down-chirp. Specifically, the first front sensor 3A and the second front sensor 3B, which are adjacent to each other, have different chirp directions, that is, different directions of frequency change over time. Similarly, the second front sensor 3B has different chirp directions from the first front sensor 3A and the third front sensor 3C adjacent thereto. Also, the third front sensor 3C has different chirp directions from the second front sensor 3B and the fourth front sensor 3D adjacent thereto. Also, the third front sensor 3C has different chirp directions from the second front sensor 3B and the fourth front sensor 3D adjacent thereto. Also, the third front sensor 3C has different chirp directions from the fourth front sensor 3D adjacent thereto.

[0055] (effect) Hereinafter, the effects achieved by this embodiment and the above-mentioned operation example will be described with reference to FIGS.

[0056] In this embodiment, as shown in Fig. 4, a first front sensor 3A to a fourth front sensor 3D, which are a plurality of ultrasonic sensors 3 provided on the same surface (i.e., the front surface in the above example) of a vehicle body C1 and arranged in the vehicle width direction, are driven with different drive signals. As a result, the first front sensor 3A to the fourth front sensor 3D transmit and receive transmission waves encoded with different codes. In particular, the chirp directions are different between adjacent sensors, where interference is most likely to occur. Therefore, according to this embodiment, interference resistance is improved.

[0057] Fig. 5 shows the frequency characteristics of the received signal, i.e., the reflected signal, corresponding to each code. In the figure, a linear waveform corresponding to the frequency characteristics of the drive signal is shown by a dashed line. Such dashed waveform corresponds to the reference signal before Doppler shift correction is performed by the correction unit 72. The Doppler shift correction by the correction unit 72 will be described later. Fig. 6 shows the amplitude waveform of the received signal corresponding to each code.

[0058] 7 to 9 show an example using a first comparison drive signal DSu and a second comparison drive signal DSd whose frequency changes over the entire range of the design transmission / reception frequency band fr0 as a comparative example. FIG. 7 shows the frequency characteristics of the first comparison drive signal DSu and the second comparison drive signal DSd. The first comparison drive signal DSu has a frequency modulation mode in which the drive frequency increases linearly from the design lower limit frequency fd to the design upper limit frequency fu, and corresponds to the symbol UP. The symbol UP indicates "up chirp". The second comparison drive signal DSd has a frequency modulation mode in which the drive frequency decreases linearly from the design upper limit frequency fu to the design lower limit frequency fd, and corresponds to the symbol DN. The symbol DN indicates "down chirp". FIG. 8 shows the frequency characteristics and the amplitude waveform of the reception signal corresponding to the first comparison drive signal DSu. FIG. 9 shows the frequency characteristics and the amplitude waveform of the reception signal corresponding to the second comparison drive signal DSd. In FIG. 8 and FIG. 9, the linear waveform corresponding to the frequency characteristics of the drive signal or the reference signal before Doppler shift correction is indicated by a dashed line.

[0059] FIG. 10 shows the effect of pulse compression by the received signal processing unit 6. (a) in FIG. 10 shows the intensity characteristics of the received signal when no pulse compression processing is performed. As shown in this figure, the peak of the received signal drops due to interference between multiple reflected waves, shown by the dashed lines. In contrast, (b) in FIG. 10 shows the intensity characteristics of the received signal when pulse compression processing is performed by the received signal processing unit 6. As shown in this figure, pulse compression shortens the signal width and suppresses the drop in the peak. This achieves a certain degree of good code discrimination and reduced interference between reflected waves.

[0060] However, when detecting an obstacle using ultrasonic waves, there is a problem that a received wave caused by a transmitted wave from another device may be mistakenly detected as a received wave caused by a transmitted wave from the sensor itself. In response to this problem, a technique has been proposed for reducing the risk of interference by encoding using FSK (Frequency Shift Keying) or the like (for example, Patent Document 1, etc.). By using such a conventional technique, the risk of interference can be reduced by assigning a unique code to each of the multiple ultrasonic sensors 3 mounted on the vehicle itself.

[0061] However, when the ultrasonic sensor 3 mounted on the vehicle faces a wall or a pole, the reflected wave from the base and the reflected wave from the front overlap. The inventors have found a problem that, in a scene where the reflected waves overlap like this, even if coding such as FSK is used for obstacle detection by the ultrasonic sensor 3, it becomes difficult to distinguish the codes due to interference between the reflected waves.

[0062] Specifically, for example, a situation is assumed in which a transmission wave having a three-bit code of "101" is transmitted from a sensor facing a wall or a pole. In the three-bit code, "1" corresponds to "UP" and "0" corresponds to "DN". In such a situation, there is a concern that an error in identifying the code will occur due to interference between the second bit of the code "0" in the front reflected wave, i.e., "DN", and the first bit of the code "1" in the root reflected wave, i.e., "UP". In particular, unlike radar that uses radio wave transmission and reception, in the ultrasonic sensor 3 that uses ultrasonic transmission and reception by the transducer 41, which is a resonant ultrasonic microphone, it is difficult to restore the code when interference occurs. For this reason, in object detection using this type of ultrasonic sensor 3, a technology is required that enables good code identification even when interference occurs between reflected waves, and that increases the number of codes.

[0063] In this regard, the inventors have found that the sweep frequency band of the drive signal is set to a high frequency side and a low frequency side with respect to the microphone center frequency fc, and by combining this with the chirp direction, multi-coding in one bit can be realized. Specifically, when N frequency bands are set within the design transmission / reception frequency band fr0 and two chirp directions, up-chirp and down-chirp, are used, "N×2" types of codes can be used per bit (for example, N=2 in the example of FIG. 3). In this embodiment, such multi-coding and pulse compression enable good code identification even if interference occurs between reflected waves. Therefore, according to this embodiment, it is possible to provide an object detection device with even improved code identification performance.

[0064] 11 and 12 show an overview of Doppler shift correction by the correction unit 72. When the relative speed between the vehicle itself and the object B is high, the Doppler shift becomes a problem. When the Doppler shift occurs, as shown in FIG. 11(a), even if the wave is normal, a mismatch occurs between the received signal and the reference signal, and the code cannot be recognized. In particular, the configuration of this embodiment has a unique problem in that it is easily affected by the Doppler shift and the positional relationship in the lateral direction (i.e., the vehicle width direction) associated with the directivity.

[0065] Therefore, the correction unit 72 corrects the reference signal as shown in Fig. 11(b) according to the moving speed of the host vehicle, i.e., the vehicle speed. Specifically, referring to Fig. 12, the relative position coordinates B(X,Y) of the object B with respect to the host vehicle can be calculated based on the relative position coordinates B(X,Y) and the vehicle speed vector V of the host vehicle. Relative velocity vectors V1, V2 between each of the two ultrasonic sensors 3 and the object B are calculated based on the relative velocity vectors V1, V2. The correction amount of the reference signal can be calculated based on the relative velocity vectors V1, V2.

[0066] (Example 2) Fig. 13 shows another specific example of the drive signal. Fig. 14 shows the frequency characteristics of the received signal, i.e., the reflected signal, corresponding to each symbol shown in Fig. 13. In the following description of the operation example, the same symbols are used for parts that are the same as or equivalent to those in the above operation example 1. Therefore, in the following description of the operation example, for elements having the same symbols as those in the above operation example 1, the description in the above operation example 1 may be used as appropriate unless there is a technical contradiction or special additional explanation. The same applies to other operation examples described later.

[0067] In this example, the drive signal generation unit 5 can selectively output the first drive signal DS1 to the fourth drive signal DS4, which are four types of drive signals having different frequency bands and / or frequency modulation modes. That is, the drive control unit 71 controls which of the first drive signal DS1 to the fourth drive signal DS4 the drive signal generation unit 5 outputs.

[0068] The transducer 41 stably vibrates ultrasonically at the resonant frequency or the microphone center frequency fc, which is a frequency close to the resonant frequency. Therefore, once the transducer 41 is excited at a frequency close to the microphone center frequency fc, the vibration frequency is difficult to change from that frequency. Therefore, at frequencies close to the microphone center frequency fc, the frequency of the reflected wave is difficult to change. In this regard, when transmitting a transmission wave, the frequency band of the received signal can be widened by sweeping the drive frequency so as to cross the microphone center frequency fc.

[0069] Therefore, in this example, the drive control unit 71 causes a first frequency band fr1, whose center frequency is higher than the microphone center frequency fc, and a second frequency band fr2, whose center frequency is lower than the microphone center frequency fc, to overlap each other in the vicinity of the microphone center frequency fc. Specifically, the lower limit frequency of the first frequency band fr1 is lower than the microphone center frequency fc. Meanwhile, the upper limit frequency of the first frequency band fr1 is the design upper limit frequency fu. In contrast, the upper limit frequency of the second frequency band fr2 is higher than the microphone center frequency fc. Meanwhile, the lower limit frequency of the second frequency band fr2 is the design lower limit frequency fd.

[0070] Similarly, the drive control unit 71 partially overlaps a third frequency band fr3, whose center frequency is higher than the microphone center frequency fc, with a fourth frequency band fr4, whose center frequency is lower than the microphone center frequency fc, near the microphone center frequency fc. Specifically, the lower limit frequency of the third frequency band fr3 is lower than the microphone center frequency fc. Meanwhile, the upper limit frequency of the third frequency band fr3 is the design upper limit frequency fu. In contrast, the upper limit frequency of the fourth frequency band fr4 is higher than the microphone center frequency fc. Meanwhile, the lower limit frequency of the fourth frequency band fr4 is the design lower limit frequency fd. Also, in this example, the first frequency band fr1 and the third frequency band fr3 are the same, and the second frequency band fr2 and the fourth frequency band fr4 are the same.

[0071] That is, in this example, when the start frequency of the drive signal is near the microphone center frequency fc, the drive control unit 71 sets the start frequency to the opposite side of the microphone center frequency fc to the end frequency of the drive signal. On the other hand, when the end frequency of the drive signal is near the microphone center frequency fc, the drive control unit 71 sets the end frequency to the opposite side of the microphone center frequency fc to the start frequency of the drive signal. This makes it possible to widen the frequency band of the received signal, thereby improving the identification performance.

[0072] (Example 3) Fig. 15 shows yet another specific example of the drive signal. Fig. 16 shows the frequency characteristics of the received signal, that is, the reflected signal, corresponding to each code shown in Fig. 15.

[0073] When performing "N x 2" types of multi-coding per bit by combining N frequency bands set within the design transmission / reception frequency band fr0 with two types of chirp directions, up-chirp and down-chirp, it is preferable that there is no difference in discrimination performance among the multiple types of codes. In other words, if the discrimination ability of a certain code is too high or too low compared to the discrimination ability of other codes, it leads to a decrease in the overall discrimination performance.

[0074] The transducer 41, which is a resonant ultrasonic microphone, stably vibrates ultrasonically at the microphone center frequency fc, which is the resonant frequency or a frequency close to the resonant frequency. Therefore, once the transducer 41 is excited at a frequency close to the microphone center frequency fc, the vibration frequency is difficult to change from that frequency. In other words, the ease of sweeping the frequency of the actual transmission wave differs depending on the sweep mode of the drive frequency. Therefore, in this example, the drive control unit 71 sets the frequency band and / or the number of pulses in the drive signal so as to suppress the difference in frequency bandwidth in the received wave between multiple codes.

[0075] Specifically, in this example, the drive control unit 71 increases the frequency band and the number of pulses in the first drive signal DS1 (i.e., reference symbol UH) and the fourth drive signal DS4 (i.e., reference symbol DL), which are characterized by a frequency sweep in which the drive frequency moves away from the microphone center frequency fc over time, as shown in Fig. 15. The dashed lines in Fig. 15 indicate the state before the frequency band and the number of pulses are increased. On the other hand, the drive control unit 71 does not increase the frequency band and the number of pulses in the second drive signal DS2 (i.e., reference symbol UL) and the third drive signal DS3 (i.e., reference symbol DH), which are characterized by a frequency sweep in which the drive frequency changes toward the microphone center frequency fc over time.

[0076] In this way, in this example, whether or not the driving frequency band crosses the microphone center frequency fc is set by the code. Also, in this example, the number of pulses in the driving signal is set by the code. This makes it possible to improve the overall discrimination performance by making the discrimination performance between many types of codes as uniform as possible.

[0077] (Example 4) 17 shows yet another specific example of the drive signal. In the above operation examples 1 to 3, a combination of two frequency bands set within the designed transmission / reception frequency band fr0 and two types of chirp encoding, up-chirp and down-chirp, allows for "2×2" types of multi-encoding per bit. In contrast, this example allows for "4×2" types of multi-encoding per bit by combining four frequency bands set within the designed transmission / reception frequency band fr0 and two types of chirp encoding, up-chirp and down-chirp.

[0078] In the figure, the upper intermediate frequency fmu is a frequency that is intermediate, i.e., a median value, between the microphone center frequency fc and the design upper limit frequency fu, and the lower intermediate frequency fmd is a frequency that is intermediate, i.e., a median value, between the microphone center frequency fc and the design lower limit frequency fd.

[0079] Specifically, in this example, the drive control unit 71 controls which of the first drive signal DS1 to the eighth drive signal DS8 the drive signal generation unit 5 outputs. The first drive signal DS1 to the eighth drive signal DS8 have different frequency bands and / or frequency modulation modes. The first frequency band fr1 to the eighth frequency band fr8 are frequency bands corresponding to the first drive signal DS1 to the eighth drive signal DS8, respectively.

[0080] The center frequency of the first frequency band fr1 is higher than the microphone center frequency fc. In this example, the lower limit frequency of the first frequency band fr1 is the microphone center frequency fc. Also, the upper limit frequency of the first frequency band fr1 is the upper intermediate frequency fmu. The first drive signal DS1 corresponds to the symbol UH1. The symbol UH1 is characterized by a frequency modulation mode in which the frequency increases over time within the first frequency band fr1. Specifically, the symbol UH1 corresponds to an "up-chirp" in which the drive frequency increases linearly from the lower limit frequency to the upper limit frequency in the first frequency band fr1.

[0081] The center frequency of the second frequency band fr2 is lower than the microphone center frequency fc. Moreover, the upper limit frequency of the second frequency band fr2 is lower than the upper limit frequency of the first frequency band fr1. Moreover, the lower limit frequency of the second frequency band fr2 is lower than the lower limit frequency of the first frequency band fr1. In other words, the second frequency band fr2 corresponds to the first frequency band fr1 offset to the lower frequency side.

[0082] In this example, the lower limit frequency of the second frequency band fr2 is the lower intermediate frequency fmd. The upper limit frequency of the second frequency band fr2 is the microphone center frequency fc. The second drive signal DS2 corresponds to the symbol UL1. The symbol UL1 is characterized by a frequency modulation mode in which the frequency increases over time within the second frequency band fr2. Specifically, the symbol UL1 corresponds to an "up-chirp" in which the drive frequency increases linearly from the lower limit frequency to the upper limit frequency in the second frequency band fr2.

[0083] The center frequency of the third frequency band fr3 is higher than the microphone center frequency fc. In this example, the lower limit frequency of the third frequency band fr3 is the microphone center frequency fc. The upper limit frequency of the third frequency band fr3 is the upper intermediate frequency fmu. The third drive signal DS3 corresponds to the symbol DH1. The symbol DH1 is characterized by a frequency modulation mode in which the frequency decreases over time in the third frequency band fr3. Specifically, the symbol DH1 corresponds to a "down chirp" in which the drive frequency increases linearly from the upper limit frequency to the lower limit frequency in the third frequency band fr3.

[0084] The center frequency of the fourth frequency band fr4 is lower than the microphone center frequency fc. The upper limit frequency of the fourth frequency band fr4 is lower than the upper limit frequency of the third frequency band fr3. The lower limit frequency of the fourth frequency band fr4 is lower than the lower limit frequency of the third frequency band fr3. In other words, the fourth frequency band fr4 corresponds to the third frequency band fr3 offset to the lower frequency side.

[0085] In this example, the lower limit frequency of the fourth frequency band fr4 is the lower intermediate frequency fmd. The upper limit frequency of the fourth frequency band fr4 is the microphone center frequency fc. The fourth drive signal DS4 corresponds to the symbol DL1. The symbol DL1 is characterized by a frequency modulation mode in which the frequency decreases over time in the fourth frequency band fr4. Specifically, the symbol DL1 corresponds to a "down chirp" in which the drive frequency increases linearly from the upper limit frequency to the lower limit frequency in the fourth frequency band fr4.

[0086] The center frequency of the fifth frequency band fr5 is higher than the microphone center frequency fc. In this example, the lower limit frequency of the fifth frequency band fr5 is the upper intermediate frequency fmu. The upper limit frequency of the fifth frequency band fr5 is the design upper limit frequency fu. The fifth drive signal DS5 corresponds to the symbol UH2. The symbol UH2 is characterized by a frequency modulation mode in which the frequency increases over time in the fifth frequency band fr5. Specifically, the symbol UH2 corresponds to an "up-chirp" in which the drive frequency increases linearly from the lower limit frequency to the upper limit frequency in the fifth frequency band fr5.

[0087] The upper limit frequency of the fifth frequency band fr5 is higher than the upper limit frequency of the first frequency band fr1. Also, the lower limit frequency of the fifth frequency band fr5 is higher than the lower limit frequency of the first frequency band fr1. In other words, the fifth frequency band fr5 corresponds to the first frequency band fr1 offset to the higher frequency side.

[0088] The center frequency of the sixth frequency band fr6 is lower than the microphone center frequency fc. In this example, the lower limit frequency of the sixth frequency band fr6 is the design lower limit frequency fd. The upper limit frequency of the sixth frequency band fr6 is the lower intermediate frequency fmd. The sixth drive signal DS6 corresponds to the symbol UL2. The symbol UL2 is characterized by a frequency modulation mode in which the frequency increases over time in the sixth frequency band fr6. Specifically, the symbol UL2 corresponds to an "up-chirp" in which the drive frequency increases linearly from the lower limit frequency to the upper limit frequency in the sixth frequency band fr6.

[0089] The upper limit frequency of the sixth frequency band fr6 is lower than the upper limit frequency of the second frequency band fr2. The lower limit frequency of the sixth frequency band fr6 is lower than the lower limit frequency of the second frequency band fr2. In other words, the sixth frequency band fr6 corresponds to the second frequency band fr2 offset to the lower frequency side.

[0090] The center frequency of the seventh frequency band fr7 is higher than the microphone center frequency fc. In this example, the lower limit frequency of the seventh frequency band fr7 is the upper intermediate frequency fmu. The upper limit frequency of the seventh frequency band fr7 is the design upper limit frequency fu. The seventh drive signal DS7 corresponds to the symbol DH2. The symbol DH2 is characterized by a frequency modulation mode in which the frequency decreases over time within the seventh frequency band fr7. Specifically, the symbol DH2 corresponds to a "down chirp" in which the drive frequency increases linearly from the upper limit frequency to the lower limit frequency in the seventh frequency band fr7.

[0091] The seventh frequency band fr7 has a higher upper limit frequency than the third frequency band fr3. The seventh frequency band fr7 has a higher lower limit frequency than the third frequency band fr3. In other words, the seventh frequency band fr7 is equivalent to the third frequency band fr3 offset to the higher frequency side.

[0092] The center frequency of the eighth frequency band fr8 is lower than the microphone center frequency fc. In this example, the lower limit frequency of the eighth frequency band fr8 is the design lower limit frequency fd. The upper limit frequency of the eighth frequency band fr8 is the lower intermediate frequency fmd. The eighth drive signal DS8 corresponds to the symbol DL2. The symbol DL2 is characterized by a frequency modulation mode in which the frequency decreases over time in the eighth frequency band fr8. Specifically, the symbol DL2 corresponds to a "down chirp" in which the drive frequency increases linearly from the upper limit frequency to the lower limit frequency in the eighth frequency band fr8.

[0093] The upper limit frequency of the eighth frequency band fr8 is lower than the upper limit frequency of the fourth frequency band fr4. Also, the lower limit frequency of the eighth frequency band fr8 is lower than the lower limit frequency of the fourth frequency band fr4. That is, the eighth frequency band fr8 corresponds to the fourth frequency band fr4 offset to the lower frequency side.

[0094] In this example, the first frequency band fr1 is the same as the third frequency band fr3. The second frequency band fr2 is the same as the fourth frequency band fr4. The fifth frequency band fr5 is the same as the seventh frequency band fr7. The sixth frequency band fr6 is the same as the eighth frequency band fr8. The first frequency band fr1, the second frequency band fr2, the fifth frequency band fr5, and the sixth frequency band fr6 are the respective bands obtained by dividing the designed transmission / reception frequency band fr0 into four. Similarly, the third frequency band fr3, the fourth frequency band fr4, the seventh frequency band fr7, and the eighth frequency band fr8 are the respective bands obtained by dividing the designed transmission / reception frequency band fr0 into four.

[0095] In this example, four frequency bands are set within the design transmission / reception frequency band fr0, and two chirp directions, up-chirp and down-chirp, are used, making it possible to use "4 x 2" types of codes per bit. This further increases the number of code types that can be set per bit, thereby enabling good code identification.

[0096] (Example 5) Fig. 18 shows yet another specific example of the drive signal. This example corresponds to the introduction of the method of operation example 3 shown in Fig. 15 to operation example 5 shown in Fig. 17. That is, this example is intended to equalize the identifiability of the eight types of codes UH1 to DL2.

[0097] In the ultrasonic sensor 3 that uses the transducer 41, which is a resonant ultrasonic microphone, to transmit and receive ultrasonic waves, when driven at a drive frequency far from the microphone center frequency fc, the transmission efficiency is lower than when driven at the microphone center frequency fc or a drive frequency close to it. Therefore, in this example, the drive control unit 71 increases the frequency band and / or the number of pulses in the drive signal as the code corresponding to the frequency band farther away from the microphone center frequency fc.

[0098] Specifically, in this example, the drive control section 71 increases the frequency bands and / or the number of pulses in the fifth drive signal DS5 to the eighth drive signal DS8 corresponding to the fifth frequency band fr5 to the eighth frequency band fr8, which are farther away from the microphone center frequency fc, among the first frequency band fr1 to the eighth frequency band fr8, compared to the example in Fig. 17 (i.e., see the dashed line in Fig. 18). In contrast, the drive control section 71 sets the frequency bands and the number of pulses in the first drive signal DS1 to the fourth drive signal DS4, which correspond to the first frequency band fr1 to the fourth frequency band fr4, to be the same as those in the example in Fig. 17.

[0099] In this way, in this example, the drive frequency band and the number of pulses in the drive signal are set depending on the code, which makes it possible to equalize the discrimination performance between various types of codes as much as possible, thereby improving the overall discrimination performance.

[0100] (Example 6) 19A to 19D, like FIG. 4, show an example of driving the plurality of ultrasonic sensors 3, ie, the first front sensor 3A to the fourth front sensor 3D, arranged in the vehicle width direction on the front surface of the vehicle body C1.

[0101] In this embodiment, the first front sensor 3A to the fourth front sensor 3D perform transmission and reception operations at a predetermined time period. Here, a total of four transmissions and receptions, in which each of the first front sensor 3A to the fourth front sensor 3D performs transmission and reception once, are referred to as "one cycle." That is, in this embodiment, the second front sensor 3B performs transmission and reception operations at the cycle start time t1, the third front sensor 3C performs transmission and reception operations at the intermediate time t2, and the first front sensor 3A and the fourth front sensor 3D perform transmission and reception operations at the cycle end time t3. "One cycle" is the period from the transmission of the transmission wave at the cycle start time t1 to the end of the reception process corresponding to the transmission of the transmission wave at the cycle end time t3. The cycle start time t1 arrives repeatedly at a predetermined time period while the operating condition of the in-vehicle system 1, i.e., the obstacle detection condition, is satisfied.

[0102] In this embodiment, as shown in Figures 19A to 19D, a first front sensor 3A to a fourth front sensor 3D, which are a plurality of ultrasonic sensors 3 provided on the same surface of a vehicle body C1 (i.e., the front surface in the example of Figures 19A to 19D) and arranged in the vehicle width direction, are driven by different drive signals corresponding to different codes in one cycle. At this time, in this embodiment, a code different from that of other sensors is assigned to the drive signal of the sensor itself so that the frequency changes in a different direction from that of other adjacent sensors. Also, in this embodiment, a different code is assigned to the drive signal that drives the sensor itself for each cycle.

[0103] In this example, it is assumed that there are four types of codes that can be assigned to the drive signal, as shown in Fig. 3, Fig. 13, or Fig. 15. In this case, in this embodiment, four types of codes are assigned to the drive signal that drives the local sensor in four cycles.

[0104] 19A, in the first cycle, the sign of the transmission wave from the second front sensor 3B that is driven at the cycle start time t1 is set to UH. The sign of the transmission wave from the third front sensor 3C that is driven at the intermediate time t2 is set to DL. And the signs of the transmission waves from the first front sensor 3A and the fourth front sensor 3D that are driven at the cycle end time t3 are set to DH and UL, respectively.

[0105] 19B, in the second cycle, the sign of the transmission wave from the second front sensor 3B, which is driven at the cycle start time t1, is set to DL. The sign of the transmission wave from the third front sensor 3C, which is driven at the intermediate time t2, is set to UH. And the signs of the transmission waves from the first front sensor 3A and the fourth front sensor 3D, which are driven at the cycle end time t3, are set to UL and DH, respectively.

[0106] 19C, in the third cycle, the sign of the transmission wave from the second front sensor 3B that is driven at the cycle start time t1 is set to UL. The sign of the transmission wave from the third front sensor 3C that is driven at the intermediate time t2 is set to DH. And the signs of the transmission waves from the first front sensor 3A and the fourth front sensor 3D that are driven at the cycle end time t3 are set to DL and UH, respectively.

[0107] 19D, in this embodiment, the sign of the transmission wave from the second front sensor 3B, which is driven at the cycle start time t1, in the fourth cycle is set to DH. The sign of the transmission wave from the third front sensor 3C, which is driven at the intermediate time t2, is set to UL. And the signs of the transmission waves from the first front sensor 3A and the fourth front sensor 3D, which are driven at the cycle end time t3, are set to UH and DL, respectively.

[0108] According to this embodiment, by assigning a unique code to each of the ultrasonic sensors 3 mounted on the vehicle, the risk of interference within the vehicle can be reduced. Also, by changing the code transmitted by one ultrasonic sensor 3 for each transmission, the risk of interference with sensors mounted on other vehicles can be reduced. Therefore, according to this embodiment, good code identification is possible.

[0109] (Modification) The present invention is not limited to the above embodiment. Therefore, the above embodiment can be modified as appropriate. Representative modified examples will be described below. In the following description of the modified examples, differences from the above embodiment will be mainly described. In addition, the same reference numerals are used for parts that are the same or equivalent to each other in the above embodiment and the modified examples. Therefore, in the following description of the modified examples, the description of the above embodiment can be appropriately used for components having the same reference numerals as the above embodiment, unless there is a technical contradiction or special additional explanation.

[0110] All or part of the electronic control unit 2 may be configured to include a digital circuit configured to enable the above-mentioned operations, such as an ASIC or FPGA. ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field Programmable Gate Array. In other words, in the electronic control unit 2, an on-vehicle microcomputer portion and a digital circuit portion may coexist.

[0111] The electronic control unit 2 and the ultrasonic sensor 3 are not limited to those mounted on an automobile, i.e., a vehicle, and may be mounted on a ship or an aircraft, for example.

[0112] The ultrasonic sensor 3 is not limited to a configuration capable of transmitting and receiving ultrasonic waves by a single transducer 41 as shown in Fig. 2. That is, for example, a transmitting transducer 41 electrically connected to a transmitting circuit 42 and a receiving transducer 41 electrically connected to a receiving circuit 43 may be provided in parallel.

[0113] The configuration of each unit such as the transmission circuit 42 and the reception circuit 43 is not limited to the specific example shown in the above embodiment. That is, for example, the digital / analog conversion circuit may be provided in the drive signal generation unit 5 instead of the transmission circuit 42. Also, the transmission circuit 42 may be integrated with the drive signal generation unit 5. Similarly, the reception circuit 43 may be integrated with the reception signal processing unit 6.

[0114] All or part of the functional configurations in the sensor control unit 7 may be provided in the electronic control device 2. That is, the object detection device according to the present invention may be configured by at least one of the electronic control device 2 and the ultrasonic sensor 3.

[0115] All or part of the sensor control unit 7 may be configured to include a digital circuit configured to enable the above-mentioned operations, such as an ASIC or FPGA. ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field Programmable Gate Array. In other words, in the sensor control unit 7, an in-vehicle microcomputer portion and a digital circuit portion may coexist.

[0116] The program according to the present invention, which enables the execution of various operations, procedures, or processes described in the above embodiment, can be downloaded or upgraded via V2X communication. V2X is an abbreviation for Vehicle to X. Alternatively, such a program can be downloaded or upgraded via a terminal device provided in a manufacturing plant, a maintenance plant, a dealer, or the like of the vehicle C. Such a program may be stored on a memory card, an optical disk, a magnetic disk, or the like.

[0117] In this way, each of the above functional configurations and methods may be realized by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, each of the above functional configurations and methods may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, each of the above functional configurations and methods may be realized by one or more dedicated computers configured by combining a processor and a memory programmed to execute one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored in a computer-readable non-transient tangible storage medium as instructions to be executed by a computer. In other words, each of the above functional configurations and methods may be expressed as a computer program including a procedure for realizing the same, or as a non-transient tangible storage medium storing the program.

[0118] The present invention is not limited to the specific functional configuration and operation example shown in the above embodiment. That is, for example, in Fig. 3, the lower limit frequency of the first frequency band fr1 may be near the microphone center frequency fc, the upper limit frequency of the second frequency band fr2 may be near the microphone center frequency fc, the lower limit frequency of the third frequency band fr3 may be near the microphone center frequency fc, and the upper limit frequency of the fourth frequency band fr4 may be near the microphone center frequency fc.

[0119] 3, the first frequency band fr1 and the third frequency band fr3 may be different from each other. That is, the first frequency band fr1 and the third frequency band fr3 may have different center frequencies and / or frequency bandwidths. Similarly, the second frequency band fr2 and the fourth frequency band fr4 may not be the same.

[0120] In Fig. 13, the first frequency band fr1 and the third frequency band fr3 may be the same or different. That is, the first frequency band fr1 and the third frequency band fr3 may have different center frequencies and / or frequency bandwidths. Similarly, the second frequency band fr2 and the fourth frequency band fr4 may be the same or different. The same applies to Fig. 17.

[0121] The second drive signal DS2 and the third drive signal DS3 in FIG. 15 can be replaced with those in FIG.

[0122] 17, the fifth frequency band fr5 and the seventh frequency band fr7 may be different from each other. Similarly, the sixth frequency band fr6 and the eighth frequency band fr8 may be different from each other.

[0123] The frequency change may not be linear, but may be curved. The frequency change may not be monotonically increasing or decreasing. That is, for example, referring to FIG. 13, the first drive signal DS1 corresponding to the symbol UH may have a frequency characteristic in which the drive frequency slightly drops from the microphone center frequency fc and then rises to the design upper limit frequency fu. This frequency modulation mode is also generally characterized by a frequency modulation mode in which the frequency rises over time within the first frequency band fr1, and may be called an "up chirp". Similarly, the fourth drive signal DS4 corresponding to the symbol DL may have a frequency characteristic in which the drive frequency slightly rises from the microphone center frequency fc and then falls to the design lower limit frequency fd. This frequency modulation mode is also generally characterized by a frequency modulation mode in which the frequency drops over time within the fourth frequency band fr4, and may be called a "down chirp".

[0124] The center frequency may be a median value or an average value.

[0125] Needless to say, the elements constituting the above-mentioned embodiment are not necessarily essential, except when expressly stated as essential or when considered to be obviously essential in principle. Furthermore, when the numbers, amounts, ranges, etc. of the components are mentioned, the present invention is not limited to the specific values, except when expressly stated as essential or when clearly limited to a specific value in principle. Similarly, when the shapes, directions, positional relationships, etc. of the components are mentioned, the present invention is not limited to the shapes, directions, positional relationships, etc., except when expressly stated as essential or when clearly limited to a specific shape, direction, positional relationship, etc. in principle.

[0126] The modified examples are not limited to the above examples. In addition, multiple modified examples may be combined with each other. Furthermore, all or part of the above embodiment and all or part of the modified examples may be combined with each other. [Explanation of symbols]

[0127] 2. Electronic control device 3. Ultrasonic Sensor 4 Transmitter / receiver 40A Transmitter 40B Receiver 7 Sensor control section 71 Drive control unit 72 Correction section 73 Detection unit 74 Judgment section

Claims

1. An object detection device (3) configured to detect an object (B) around a moving body (C) when mounted on the moving body, A drive control unit (71) that sets a frequency modulation mode within a predetermined frequency band in a drive signal that drives a transmission unit (40A) to transmit to the outside a transmission wave that is an ultrasonic wave encoded by frequency modulation; a detection unit (73) that detects the object based on a reception signal corresponding to a reception result by a receiving unit (40B) of a reception wave including a reflected wave of the transmission wave by the object; Equipped with The detection unit has a determination unit (74) that determines a code included in the received wave based on a match between a reference signal corresponding to the drive signal and the received signal, the drive control unit is configured to select and set, as a code to be assigned to the drive signal, any one of a plurality of types of codes including at least a first code characterized by a frequency modulation mode in which a frequency increases over time in a first frequency band, a second code characterized by a frequency modulation mode in which a frequency increases over time in a second frequency band different from the first frequency band, a third code characterized by a frequency modulation mode in which a frequency decreases over time in a third frequency band, and a fourth code characterized by a frequency modulation mode in which a frequency decreases over time in a fourth frequency band different from the third frequency band, and to increase a frequency band and / or a number of pulses in the drive signal as the code corresponding to a frequency band farther away from a center frequency of the transmission unit; an upper limit frequency of the first frequency band is higher than an upper limit frequency of the second frequency band; a lower limit frequency of the first frequency band is higher than a lower limit frequency of the second frequency band, an upper limit frequency of the third frequency band is higher than an upper limit frequency of the fourth frequency band; a lower limit frequency of the third frequency band is higher than a lower limit frequency of the fourth frequency band; Object detection device.

2. The drive control unit is When the start frequency of the drive signal is close to the center frequency of the transmitter, the start frequency is set to the opposite side of the center frequency of the transmitter from the end frequency of the drive signal; When the end frequency of the drive signal is close to the center frequency of the transmitter, the end frequency is set to the opposite side of the center frequency of the transmitter from the start frequency of the drive signal. The object detection device according to claim 1 .

3. An object detection device (3) configured to detect an object (B) around a moving body (C) when mounted on the moving body, A drive control unit (71) that sets a frequency modulation mode within a predetermined frequency band in a drive signal that drives a transmission unit (40A) to transmit to the outside a transmission wave that is an ultrasonic wave encoded by frequency modulation; a detection unit (73) that detects the object based on a reception signal corresponding to a reception result by a receiving unit (40B) of a reception wave including a reflected wave of the transmission wave by the object; Equipped with The detection unit has a determination unit (74) that determines a code included in the received wave based on a match between a reference signal corresponding to the drive signal and the received signal, The drive control unit is a code to be assigned to the drive signal is selected and set from a plurality of types of codes including at least a first code characterized by a frequency modulation mode in which the frequency increases over time in a first frequency band, a second code characterized by a frequency modulation mode in which the frequency increases over time in a second frequency band different from the first frequency band, a third code characterized by a frequency modulation mode in which the frequency decreases over time in a third frequency band, and a fourth code characterized by a frequency modulation mode in which the frequency decreases over time in a fourth frequency band different from the third frequency band; When the start frequency of the drive signal is close to the center frequency of the transmitter, the start frequency is set to the opposite side of the center frequency of the transmitter from the end frequency of the drive signal; When the end frequency of the drive signal is close to the center frequency of the transmitter, the end frequency is configured to be on the opposite side of the center frequency of the transmitter from the start frequency of the drive signal, an upper limit frequency of the first frequency band is higher than an upper limit frequency of the second frequency band; a lower limit frequency of the first frequency band is higher than a lower limit frequency of the second frequency band, an upper limit frequency of the third frequency band is higher than an upper limit frequency of the fourth frequency band; a lower limit frequency of the third frequency band is higher than a lower limit frequency of the fourth frequency band; Object detection device.

4. the drive control unit sets a frequency band and / or a pulse number in the drive signal so as to suppress a difference in frequency bandwidth in the received wave among the first code, the second code, the third code, and the fourth code. The object detection device according to any one of claims 1 to 3.

5. A correction unit (72) for correcting the reference signal in accordance with the moving speed of the moving object is further provided. The object detection device according to any one of claims 1 to 4.

6. An object detection device (3) configured to detect an object (B) around a moving body (C) when mounted on the moving body, A drive control unit (71) that sets a frequency modulation mode within a predetermined frequency band in a drive signal that drives a transmission unit (40A) to transmit to the outside a transmission wave that is an ultrasonic wave encoded by frequency modulation; a correction unit (72) that corrects a reference signal corresponding to the drive signal in accordance with a moving speed of the moving body; a detection unit (73) that detects the object based on a reception signal corresponding to a reception result by a receiving unit (40B) of a reception wave including a reflected wave of the transmission wave by the object; Equipped with The detection unit has a determination unit (74) that determines a code included in the received wave based on a match between the reference signal and the received signal, the drive control unit is configured to select and set, as a code to be assigned to the drive signal, any one of a plurality of types of codes including at least a first code characterized by a frequency modulation mode in which a frequency increases over time within a first frequency band, a second code characterized by a frequency modulation mode in which a frequency increases over time within a second frequency band different from the first frequency band, a third code characterized by a frequency modulation mode in which a frequency decreases over time within a third frequency band, and a fourth code characterized by a frequency modulation mode in which a frequency decreases over time within a fourth frequency band different from the third frequency band; an upper limit frequency of the first frequency band is higher than an upper limit frequency of the second frequency band; a lower limit frequency of the first frequency band is higher than a lower limit frequency of the second frequency band, an upper limit frequency of the third frequency band is higher than an upper limit frequency of the fourth frequency band; a lower limit frequency of the third frequency band is higher than a lower limit frequency of the fourth frequency band; Object detection device.

7. The correction unit corrects the reference signal in accordance with the moving speed and a relative position of the object with respect to the moving body. The object detection device according to claim 5 or 6.

8. A plurality of the transmitters are arranged in an arrangement direction intersecting with the traveling direction of the moving body, and among the plurality of the transmitters, the transmitter currently driven by the drive control unit is defined as a self-transmitting unit, and the other transmitters different from the self-transmitting unit are defined as other-transmitting units. The drive control unit assigns a code different from that of the other-transmitting units to the drive signal so that the frequency of the other-transmitting units changes in a direction different from that of the adjacent other-transmitting units. An object detection device according to any one of claims 1 to 7.

9. An object detection device (3) configured to detect an object (B) around a moving body (C) when mounted on the moving body, A drive control unit (71) that sets a frequency modulation mode within a predetermined frequency band in a drive signal that drives a transmission unit (40A) to transmit to the outside a transmission wave that is an ultrasonic wave encoded by frequency modulation; a detection unit (73) that detects the object based on a reception signal corresponding to a reception result by a receiving unit (40B) of a reception wave including a reflected wave of the transmission wave by the object; Equipped with The detection unit has a determination unit (74) that determines a code included in the received wave based on a match between a reference signal corresponding to the drive signal and the received signal, the drive control unit is configured to select and set, as a code to be assigned to the drive signal, any one of a plurality of types of codes including at least a first code characterized by a frequency modulation mode in which a frequency increases over time within a first frequency band, a second code characterized by a frequency modulation mode in which a frequency increases over time within a second frequency band different from the first frequency band, a third code characterized by a frequency modulation mode in which a frequency decreases over time within a third frequency band, and a fourth code characterized by a frequency modulation mode in which a frequency decreases over time within a fourth frequency band different from the third frequency band; an upper limit frequency of the first frequency band is higher than an upper limit frequency of the second frequency band; a lower limit frequency of the first frequency band is higher than a lower limit frequency of the second frequency band, an upper limit frequency of the third frequency band is higher than an upper limit frequency of the fourth frequency band; a lower limit frequency of the third frequency band is higher than a lower limit frequency of the fourth frequency band, A plurality of the transmitters are arranged in an arrangement direction intersecting with the traveling direction of the moving body, and among the plurality of the transmitters, the transmitter currently driven by the drive control unit is defined as a self-transmitting unit, and the other transmitters different from the self-transmitting unit are defined as other-transmitting units. The drive control unit assigns a code different from that of the other-transmitting units to the drive signal so that the frequency of the other-transmitting units changes in a direction different from that of the adjacent other-transmitting units. Object detection device.

10. K transmitting units are arranged in an arrangement direction intersecting with the traveling direction of the moving body, and among the plurality of transmitting units, the transmitting unit currently driven by the drive control unit is defined as a local transmitting unit, and the other transmitting units different from the local transmitting unit are defined as other transmitting units, and a total of K transmissions in which each of the K transmitting units transmits the transmission wave in sequence once are defined as one cycle, and the drive control unit assigns a different code to the drive signal that drives the local transmitting unit for each cycle. An object detection device according to any one of claims 1 to 9.

11. When the number of types of codes that can be assigned to the drive signal is M, the drive control unit assigns M types of codes to the drive signal that drives the transmission unit itself in M ​​cycles. The object detection device according to claim 10.

12. An object detection device (3) configured to detect an object (B) around a moving body (C) when mounted on the moving body, A drive control unit (71) that sets a frequency modulation mode within a predetermined frequency band in a drive signal that drives a transmission unit (40A) to transmit to the outside a transmission wave that is an ultrasonic wave encoded by frequency modulation; a detection unit (73) that detects the object based on a reception signal corresponding to a reception result by a receiving unit (40B) of a reception wave including a reflected wave of the transmission wave by the object; Equipped with The detection unit has a determination unit (74) that determines a code included in the received wave based on a match between a reference signal corresponding to the drive signal and the received signal, the drive control unit is configured to select and set, as a code to be assigned to the drive signal, any one of a plurality of types of codes including at least a first code characterized by a frequency modulation mode in which a frequency increases over time within a first frequency band, a second code characterized by a frequency modulation mode in which a frequency increases over time within a second frequency band different from the first frequency band, a third code characterized by a frequency modulation mode in which a frequency decreases over time within a third frequency band, and a fourth code characterized by a frequency modulation mode in which a frequency decreases over time within a fourth frequency band different from the third frequency band; an upper limit frequency of the first frequency band is higher than an upper limit frequency of the second frequency band; a lower limit frequency of the first frequency band is higher than a lower limit frequency of the second frequency band, an upper limit frequency of the third frequency band is higher than an upper limit frequency of the fourth frequency band; a lower limit frequency of the third frequency band is higher than a lower limit frequency of the fourth frequency band, K transmitters are arranged in an arrangement direction intersecting with the traveling direction of the moving body, and among the plurality of transmitters, the transmitter currently driven by the drive control unit is defined as a local transmitter, and the other transmitters different from the local transmitter are defined as other transmitters. When a total of K transmissions in which each of the K transmitters transmits the transmission wave once in turn is defined as one cycle, the drive control unit assigns a different code to the drive signal that drives the local transmitter for each cycle, When the number of types of codes that can be assigned to the drive signal is M, the drive control unit assigns M types of codes to the drive signal that drives the transmission unit in M ​​cycles. Object detection device.

13. a center frequency of the first frequency band is higher than a center frequency of the transmission unit; a center frequency of the second frequency band is lower than a center frequency of the transmitter; a center frequency of the third frequency band is higher than a center frequency of the transmission unit; The center frequency of the fourth frequency band is lower than the center frequency of the transmitter. An object detection device according to any one of claims 1 to 12.

14. a lower limit frequency of the first frequency band is a center frequency of the transmitter or is close to the center frequency of the transmitter; an upper limit frequency of the second frequency band is a center frequency of the transmitter or is close to the center frequency of the transmitter; a lower limit frequency of the third frequency band is a center frequency of the transmitter or a frequency close to the center frequency of the transmitter; The upper limit frequency of the fourth frequency band is a center frequency of the transmitter or a frequency close to the center frequency of the transmitter. The object detection device according to claim 13.

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