JP6767862B2 - Object detection device - Google Patents

Description

The present invention relates to an object detection device that transmits an exploration wave such as an ultrasonic wave, acquires a detection wave including a reflected wave reflected by a surrounding object, and detects the object.

Conventionally, an object detection device has been realized in which ultrasonic waves are transmitted as exploration waves, and the reflected waves reflected by an object are received to detect the distance and relative velocity to the object. In such an object detection device, when there is another object detection device in the vicinity, interference occurs in which the exploration wave transmitted from the other object detection device and the reflected wave based on the exploration wave are received. There is. When interference occurs, the position of the object will be detected by the exploration wave transmitted from another object detection device and the reflected wave based on the exploration wave, and it may be determined that there is an object that does not actually exist. There is.

Conventionally, in order to suppress such interference, control has been performed to randomly change the transmission timing of the exploration wave.

Further, in Patent Document 1 below, an infrared transmitter / receiver is provided in the object detection device, and the other object detection device is irradiated with infrared rays at the transmission timing of the exploration wave to suppress interference.

Japanese Unexamined Patent Publication No. 2007-114081

When the transmission timing is changed randomly, one sampling cycle for transmission and reception is generally fixed, so the length of one sampling cycle should be set so that a sufficient reception standby period can be provided even at the latest transmission timing. Determine. Therefore, it becomes necessary to increase the length of one sampling cycle. As a result, the number of samplings per predetermined time is reduced, and the accuracy of control using the distance to the object or the like is lowered. In addition, it becomes necessary to have a plurality of various parameters for making the transmission timing random, which complicates the configuration.

Further, in the object detection device described in Patent Document 1, since interference is suppressed by irradiating another object detection device with infrared rays, an infrared transmitter / receiver is required. As a result, the suppression control of interference cannot be completed by one object detection device, and there arises a problem that the configuration of the entire system becomes complicated.

That is, in any case, it is assumed that the reflected wave is received after creating a situation in which the interference wave is not received without determining whether the received wave is a reflected wave or an interference wave. , Problems such as deterioration of object detection accuracy and complicated configuration occur.

The present invention has been made to solve the above problems, and a main object thereof is to provide an object detection device capable of appropriately determining a received wave that is not a reflected wave of a search wave transmitted by itself. It is in.

The present invention is an object detection device that transmits an exploration wave at a predetermined transmission / reception opportunity, acquires a received wave including a reflected wave from a surrounding object, and detects the object, and transmits the exploration wave and the said. A transmission / reception unit that receives a received wave, a distance calculation unit that calculates a direct detection distance indicating a distance to the object based on a transmission timing of the exploration wave and a reception timing of the reception wave, and a distance calculation unit of the exploration wave. Calculated at this transmission / reception opportunity with the first relative velocity calculation unit that obtains the relative velocity with the object as the first relative velocity based on the wave characteristics that are the frequency or period and the wave characteristics of the received wave. Based on the direct detection distance obtained and the direct detection distance acquired at the previous transmission / reception opportunity, the second relative velocity calculation unit for obtaining the relative velocity with the object as the second relative velocity, and the first relative velocity. A determination unit for determining that the received wave is not a reflected wave of the exploration wave when the difference from the second relative velocity is larger than a predetermined value is provided.

If the received wave is a reflected wave of the exploration wave and the velocity or relative velocity of the object is constant, then the second relative velocity, which is the relative velocity based on the frequency or period of the received wave, and the previous transmission / reception opportunity The first relative velocity, which is the relative velocity based on the direct detection distance obtained in this cycle and the direct detection distance acquired in this cycle, is approximately equal. Further, even if the velocity or relative velocity of the object is not constant, the difference between the first relative velocity and the second relative velocity is within a predetermined range. On the other hand, when the received wave received by the transmission / reception unit is an interference wave such as an exploration wave transmitted from another object detection device or the like, the difference between the first relative velocity and the second relative velocity is generally large. Is the target. In the above configuration, the first relative velocity and the second relative velocity are obtained respectively, and when the difference between the first relative velocity and the second relative velocity is larger than a predetermined value, it is determined that the received wave is not the reflected wave of the exploration wave. Therefore, the received wave that is not the reflected wave can be excluded more appropriately.

It is a figure which shows the structure of the object detection apparatus which concerns on 1st Embodiment. It is a figure which shows the example when the interference wave is received. It is a flowchart which shows the process which concerns on 1st Embodiment. It is a figure which shows the structure of the object detection apparatus which concerns on 3rd Embodiment. It is a figure which shows the structure of the object detection apparatus which concerns on 7th Embodiment.

<First Embodiment>
The object detection device according to the present embodiment is mounted on a vehicle which is a moving body. The object detection device transmits an exploration wave that is an ultrasonic wave at each predetermined transmission / reception opportunity, receives the reflected wave reflected by an object existing around the moving object as a reception wave, and transmits the exploration wave to the received wave. The distance between the vehicle and the object is obtained by measuring the time until reception. Then, when the distance between the vehicle and the object is shorter than a predetermined distance, the driver of the vehicle is notified of the approach to the object, or the braking device provided in the vehicle is activated.

FIG. 1 is a configuration diagram of an object detection device according to the present embodiment. The object detection device includes an ultrasonic sensor 10 and an ECU 20 communicatively connected to the ultrasonic sensor 10.

The ultrasonic sensor 10 receives a communication unit 11 that communicates with the ECU 20, a transmission control unit 12 that receives a start signal for transmission control of the exploration wave from the communication unit 11, and performs transmission control of the exploration wave, and a transmission control unit thereof. A transmission circuit 13 driven by 12 is provided. The transmission circuit 13 is driven by a drive signal from the transmission control unit 12, and drive power having a predetermined frequency is supplied to the transmission / reception unit 14.

The transmission / reception unit 14 has a known configuration including a piezoelectric element. Drive power of a predetermined frequency is supplied from the transmission circuit 13 to the piezoelectric element, and the piezoelectric element oscillates due to the drive power to transmit ultrasonic waves as exploration waves.

When the exploration wave is reflected by a surrounding object after the transmission of the exploration wave, the reflected wave, which is the reflected ultrasonic wave, is incident on the transmission / reception unit 14. Further, when there is a device for generating ultrasonic waves such as another object detection device in the vicinity, the ultrasonic waves or the like emitted from the device or the like are incident on the transmission / reception unit 14. This ultrasonic wave or the like emitted from another device or the like is referred to as an interference wave.

The piezoelectric element included in the transmission / reception unit 14 vibrates by the received wave to generate an electric signal having a frequency equal to the frequency of the received wave and having a voltage proportional to the amplitude of the received wave. The electric signal generated by the piezoelectric element is input to the receiving circuit 15. The receiving circuit 15 includes a known bandpass filter circuit, and removes a received wave having a frequency deviating from the frequency of the probe wave.

The distance calculation unit 16 obtains the time from the transmission time of the exploration wave to the reception time of the received wave, and multiplies half of the time by the speed of sound to obtain the distance to the object. Information regarding the transmission time of the exploration wave is acquired from the transmission control unit 12. On the other hand, the reception time of the received wave is set to the time when the value of the voltage acquired from the receiving circuit 15 exceeds a predetermined threshold value.

The frequency calculation unit 17 calculates the frequency of the received wave. Specifically, the period from when the voltage indicating the amplitude of the received wave exceeds the value of zero to when it reaches the value of zero again is obtained, and the reciprocal of the period is used as the frequency. Since the frequency indicates the characteristics of the received wave, it can be referred to as a wave characteristic.

The distance calculated by the distance calculation unit 16 and the frequency calculated by the frequency calculation unit 17 are transmitted from the communication unit 11 to the ECU 20.

The ultrasonic sensor 10 configured as described above may receive an interference wave, which is not a reflected wave of the exploration wave, as a received wave in order to obtain the distance to a surrounding object. In particular, when there is a device that transmits ultrasonic waves whose frequency is close to the exploration wave transmitted by the ultrasonic sensor 10, the exploration wave transmitted by the device and the reflected wave reflected by the object are used. May be received. In this case, since the frequency of the received wave is close to the frequency of its own exploration wave, there is a high possibility that it will not be removed by the receiving circuit 15 that functions as a noise filter. In this way, when the position of an object is determined based on the exploration wave or the like transmitted by another ultrasonic sensor, it may be determined that an object that does not actually exist exists.

A case where the reflected wave is received as the first wave of the received wave at the previous transmission / reception opportunity and the interference wave is received as the first wave of the received wave at the current transmission / reception opportunity will be described with reference to FIG. .. In FIG. 2, the horizontal axis is time, and the vertical axis is the amplitude of the received wave, that is, the value of the voltage output from the piezoelectric element. Further, FIG. 2 shows an example in which the object detection device and the object approach each other.

At the previous transmission / reception opportunity, the transmission control unit 12 starts transmission control at time t10, and the probe wave is transmitted from the transmission / reception wave unit at time t11, which is the transmission time. When this exploration wave is reflected by an object and the transmission / reception unit 14 receives the reflected wave, the reception time is set to time t12 when the amplitude of the reflected wave becomes equal to or greater than the threshold value. The distance between the ultrasonic sensor 10 and the object can be obtained by taking the difference between the time t11 which is the transmission time and the time t12 which is the reception time and multiplying half of the difference by the speed of sound.

In this transmission / reception opportunity, the transmission control unit 12 starts transmission control at time t20, and the search wave is transmitted from the transmission / reception wave unit at time t21, which is the transmission time, as in the previous transmission / reception opportunity. Since the distance between the object detection device and the objects existing around it is shortened, the amplitude of the reflected wave exceeds the threshold value at time t23, and the difference between time t21 and time t23 is time t11 and time t12. Is smaller than the difference with.

However, in this transmission / reception opportunity, the interference wave is received before the reception of the reflected wave, and the amplitude of the interference wave is equal to or more than the threshold value at time t22. Therefore, the distance to the object is calculated by the time. It is performed by the difference between t21 and the time t22. That is, a distance shorter than the actual distance to the object is calculated. In this case, if the driver of the vehicle is notified or the vehicle is braked based on the calculated distance, it can be said that such control is unnecessary.

Therefore, the ECU 20 included in the object detection device according to the present embodiment excludes received waves that are determined to have a high possibility of interference waves from the process of detecting the object.

The communication unit 21 included in the ECU 20 acquires the distance based on the received wave received at this transmission / reception opportunity and the frequency of the received wave from the ultrasonic sensor 10.

The first relative speed calculation unit 23 acquires the distance based on the received wave received at this transmission / reception opportunity and the reception time of the received wave via the communication unit 21. Further, the first relative velocity calculation unit 23 acquires the distance stored in the storage unit 22 at the previous transmission / reception opportunity and the time when the received wave used for calculating the distance is received from the storage unit 22. Then, the difference between the distance based on the received wave of the current transmission / reception opportunity and the distance based on the received wave of the previous transmission / reception opportunity is taken, and the difference is the reception time of the reception wave of the current cycle and the reception wave of the previous cycle. The first relative velocity Vd is calculated by dividing by the difference from the reception time of.

The second relative velocity calculation unit 24 acquires the frequency of the received wave received at this transmission / reception opportunity via the communication unit 21, and uses the frequency of the received wave and the frequency of the exploration wave to obtain the second relative velocity Vf. Is calculated. For example, the following equation (1) is used, where f is the frequency of the received wave, f0 is the frequency of the exploration wave, and c is the speed of sound.

上式（１）を変形すれば、第２相対速度Ｖｆは次式（２）で求まる。

By modifying the above equation (1), the second relative velocity Vf can be obtained by the following equation (2).

判定部２６は、第１相対速度算出部２３が算出した第１相対速度Ｖｄ、及び、第２相対速度算出部２４が算出した第２相対速度Ｖｆを取得する。判定部２６は、加えて、車両情報取得部２５から車両の速度を取得する。判定部２６は、車両の速度が所定値（例えば５ｋｍ）よりも小さい場合に、受信波が反射波であるか否かの判定を行う。これは、車両の速度が所定値以上であれば、車両は、混信波の発生源から早期に離脱することが可能であり、混信波の影響が小さいと考えられるためである。

The determination unit 26 acquires the first relative velocity Vd calculated by the first relative velocity calculation unit 23 and the second relative velocity Vf calculated by the second relative velocity calculation unit 24. In addition, the determination unit 26 acquires the speed of the vehicle from the vehicle information acquisition unit 25. The determination unit 26 determines whether or not the received wave is a reflected wave when the speed of the vehicle is smaller than a predetermined value (for example, 5 km). This is because if the speed of the vehicle is equal to or higher than a predetermined value, the vehicle can leave the source of the interference wave at an early stage, and the influence of the interference wave is considered to be small.

When the vehicle speed acquired from the vehicle information acquisition unit 25 is smaller than a predetermined value, the determination unit 26 uses the first relative velocity Vd and the second relative velocity Vf to determine whether or not the received wave is a reflected wave. judge. Specifically, the difference between the acquired first relative velocity Vd and the second relative velocity Vf is taken, and when the absolute value of the difference is larger than a predetermined value, it is determined that the received wave is not a reflected wave. If the absolute value of the difference between the first relative velocity Vd and the second relative velocity Vf is equal to or less than a predetermined value, it is highly possible that the received wave is a reflected wave, so the distance obtained by the received wave is stored in the storage unit 22. To memorize. The distance stored in the storage unit 22 is used for determining whether or not the received wave is a reflected wave at the next transmission / reception opportunity.

A series of processes executed in the object detection device configured as described above will be described with reference to the flowchart of FIG.

First, the exploration wave is transmitted in step S101, and the received wave is acquired in the subsequent step S102. In the process of step S102, the process waits until the received wave is acquired. That is, it detects a voltage value corresponding to the amplitude value of the received wave, and waits until the voltage value shows a value larger than the threshold value.

If the received wave is acquired, the process proceeds to step S103, and the distance is calculated using the transmission time of the exploration wave and the reception time of the received wave. Subsequently, the process proceeds to step S104, and the first relative velocity Vd, which is the relative velocity calculated by the distance calculated in step S103 and the distance read from the storage unit 22, is calculated.

In the following step S105, the frequency of the received wave of the current period is calculated. That is, as described above, the reciprocal of the period between the zero cross points is obtained as the frequency. When the frequency is obtained, the process proceeds to step S106, and the second relative velocity Vf is calculated by the formula of the Doppler effect using the frequency of the exploration wave and the frequency of the received wave.

If the second relative velocity Vf is obtained, the process proceeds to step S107, and it is determined whether or not the absolute value of the difference between the first relative velocity Vd and the second relative velocity Vf is larger than the threshold value Vth. That is, it is determined whether or not the difference between the first relative velocity Vd and the second relative velocity Vf is large. If an affirmative judgment is made in step S107, that is, if the absolute value of the difference between the first relative velocity Vd and the second relative velocity Vf is larger than the threshold value Vth, the received wave is likely to be an interference wave, so step S108. The detection distance acquired this time is not stored in the storage unit 22 and is discarded. Then, a series of processes is completed.

On the other hand, when a negative determination is made in step S107, that is, when the absolute value of the difference between the first relative velocity Vd and the second relative velocity Vf is equal to or less than the threshold value Vth, it is unlikely that the received wave is an interference wave. The process proceeds to step S109, and the detection distance acquired this time is stored in the storage unit 22. Then, a series of processes is completed.

If the distance based on the received wave received at the previous transmission / reception opportunity is discarded, in step S104, the distance based on the received wave received before the previous transmission / reception opportunity, that is, stored in the storage unit 22. The first relative velocity Vd is obtained by using the latest distance among the distances.

With the above configuration, the object detection device according to the present embodiment has the following effects.

When the received wave is a reflected wave of the exploration wave, it is based on the first relative velocity Vd, which is the relative velocity based on the detection distance acquired in the previous transmission / reception opportunity and the detection distance acquired in this cycle, and the frequency of the received wave. It is approximately equal to the second relative velocity Vf, which is the relative velocity. In the present embodiment, the first relative velocity Vd and the second relative velocity Vf are obtained respectively, and when the difference between the first relative velocity Vd and the second relative velocity Vf is larger than a predetermined value, the received wave is the exploration wave. Since it is determined that the wave is not a reflected wave, the received wave that is not a reflected wave can be appropriately excluded.

<Second Embodiment>
The overall configuration of the object detection device according to the present embodiment is the same as that of the first embodiment, and processing is added to the processing executed by the object detection device according to the first embodiment.

In the present embodiment, the determination unit 26 acquires the speed of the vehicle from the vehicle information acquisition unit 25 that functions as the speed acquisition unit. Then, with the object as a reference, the acquired velocity is subtracted from each of the first relative velocity Vd and the second relative velocity Vf. By doing so, the velocity of the object can be obtained assuming that the received wave is a reflected wave. In addition, based on the vehicle, the acquired speed is added to each of the first relative speed Vd and the second relative speed Vf. By doing so, the velocity of the object can be obtained assuming that the received wave is a reflected wave.

Once the velocity of the object is obtained, it is determined whether or not the velocity is greater than a predetermined threshold value. This threshold is, for example, 10 km. As described in the first embodiment, the determination performed by the determination unit is performed when the speed of the vehicle is 5 km or less, and the moving speed of the surrounding objects is also the number of moving speeds of the vehicle. This is because it is generally less than double.

If the speed of the object is greater than a predetermined value, the determination unit 26 determines that the received wave received at this transmission / reception opportunity is not a reflected wave, and discards the distance and reception time related to the received wave. On the other hand, if the velocity of the object is equal to or less than a predetermined value, the determination unit 38 stores the distance and the reception time related to the received wave in the storage unit 22.

With the above configuration, the object detection device according to the present embodiment has the following effects in addition to the effects of the object detection device according to the first embodiment.

-In determining the first relative velocity Vd and the second relative velocity Vf, even if the received wave is not the reflected wave of the exploration wave, the first relative velocity Vd and the first relative velocity Vd depend on the frequency and reception time of the received wave. 2 The deviation from the relative velocity Vf may be small. In the present embodiment, the velocity of the object is further obtained, and when the velocity of the object is larger than a predetermined value, it is determined that the received wave is not a reflected wave. That is, it is determined that the received wave is not a reflected wave on condition that the velocity of the object is a value that cannot be normally obtained. Therefore, in the present embodiment, it is possible to improve the accuracy of determining whether or not interference has occurred.

<Third Embodiment>
A part of the configuration of the object detection device according to the present embodiment is different from that of the first embodiment, and a process is added to the process executed by the object detection device according to the first embodiment.

As shown in FIG. 4, the ECU 30 includes a communication unit 31, a first relative speed calculation unit 33, and a second relative speed calculation unit 34. Since these perform the same processing as in the first embodiment, specific description thereof will be omitted.

The storage unit 32 also stores the first relative velocity Vd and the second relative velocity Vf in addition to the distance and reception time based on the received wave at the transmission / reception opportunity prior to the current transmission / reception opportunity.

The first relative acceleration calculation unit 35 calculates the first relative acceleration indicating the amount of time change of the first relative velocity Vd. Specifically, the reception time of the received wave used for calculating the first relative velocity Vd is the difference between the first relative velocity Vd read from the storage unit 32 and the first relative velocity Vd calculated at this transmission / reception opportunity. The first relative acceleration is calculated by dividing by the difference between.

The second relative acceleration calculation unit 36 calculates the second relative acceleration indicating the amount of time change of the second relative velocity Vf. Specifically, the reception time of the received wave used for calculating the second relative velocity Vf is the difference between the second relative velocity Vf read from the storage unit 32 and the second relative velocity Vf calculated at this transmission / reception opportunity. The second relative acceleration is calculated by dividing by the difference between.

The determination unit 38 acquires the first relative acceleration from the first relative acceleration calculation unit 35, and acquires the second relative acceleration from the second relative acceleration calculation unit 36. In addition to these, the determination unit 38 acquires the acceleration in the traveling direction of the vehicle from the vehicle information acquisition unit 37 that functions as an acceleration acquisition unit.

Then, the determination unit 38 adds the acceleration of the vehicle to each of the first relative acceleration and the second relative acceleration to calculate the acceleration of the object. If the acceleration of the object is larger than a predetermined value, the determination unit 38 determines that the received wave received at this transmission / reception opportunity is not a reflected wave, and determines the distance, reception time, first relative velocity Vd, and the first relative velocity Vd related to the received wave. The second relative velocity Vf is discarded. On the other hand, if the acceleration of the object is equal to or less than a predetermined value, the determination unit 38 stores the distance, reception time, first relative velocity Vd, and second relative velocity Vf related to the received wave in the storage unit 32.

With the above configuration, the object detection device according to the present embodiment has the following effects in addition to the effects of the object detection device according to the first embodiment.

-When the received wave is an interference wave, the detection distance generally changes significantly. Along with this change in the detection distance, a large change may occur in the first relative acceleration calculated by the first relative velocity Vd and the second relative acceleration calculated by the second relative velocity Vf. On the other hand, even in a situation that can actually occur, such as when the vehicle suddenly decelerates, the first relative acceleration and the second relative acceleration may change significantly. In the present embodiment, the acceleration of an object, which is the difference between the acceleration of the vehicle and the relative acceleration, is obtained, and the acceleration of the object is larger than a predetermined value, that is, the acceleration is unusual. It is determined that the received wave is not a reflected wave. As a result, it is possible to improve the accuracy of determining whether or not interference has occurred.

<Fourth Embodiment>
The object detection device according to the present embodiment has the same configuration as the object detection device according to the third embodiment, and is a part of the processing executed by the object detection device according to the third embodiment. Is changing.

The first relative acceleration calculation unit 35 and the second relative acceleration calculation unit 36 calculate the first relative acceleration and the second relative acceleration as in the third embodiment.

The determination unit 38 calculates the absolute value of the difference between the first relative acceleration and the second relative acceleration, and if the difference is larger than a predetermined value, it determines that the received wave received at this transmission / reception opportunity is not a reflected wave. , Discard the distance, reception time, and relative velocity with respect to the received wave. On the other hand, if the absolute value of the difference between the first relative acceleration and the second relative acceleration is equal to or less than a predetermined value, the determination unit 38 stores the distance, reception time, and relative speed related to the received wave in the storage unit 32.

With the above configuration, the object detection device according to the present embodiment has the following effects in addition to the effects of the object detection device according to the first embodiment.

-At the previous transmission / reception opportunity, the first relative velocity Vd is larger than the second relative velocity Vf, and the difference is within the threshold value. At this transmission / reception opportunity, the second relative velocity Vf is greater than the first relative velocity Vd. Is also large, and the difference may be within the threshold value. In such a case, even if the difference between the first relative velocity Vd and the second relative velocity Vf is small, the difference between the first relative acceleration and the second relative acceleration is large. In the present embodiment, it is determined that the received wave is not a reflected wave on condition that the difference between the first relative acceleration and the second relative acceleration is larger than a predetermined value, so whether or not interference has occurred. The determination accuracy can be improved.

<Fifth Embodiment>
The overall configuration of the object detection device according to the present embodiment is the same as that of the first embodiment, and processing is added to the processing executed by the object detection device according to the first embodiment.

Specifically, in the present embodiment, the distance calculation unit 16 has a threshold of the amplitude next to the first wave in addition to the distance based on the first wave, which is the received wave whose amplitude is first larger than the threshold. The distance based on the second wave, which is the larger received wave, is calculated. The frequency calculation unit 17 calculates the frequency of the second wave in addition to the frequency of the first wave. That is, when an interference wave is received as the first wave and a reflected wave is received as the second wave as shown in FIG. 2 of the first embodiment, the distance and frequency based on each are calculated.

The first relative speed calculation unit 23 of the ECU 20 calculates the first relative speed Vd by using the distance and the reception time based on the first wave and the distance and the reception time stored in the storage unit 22. Similarly, the first relative velocity Vd is calculated using the distance and reception time based on the second wave and the distance and reception time stored in the storage unit 22.

The second relative speed calculation unit 24 of the ECU 20 calculates the second relative speed Vf from the frequency of the first wave. Similarly, the second relative velocity Vf is calculated from the frequency of the second wave.

The determination unit 26 obtains the absolute value of the difference between the first relative velocity Vd and the second relative velocity Vf based on the first wave. Similarly, the absolute value of the difference between the first relative velocity Vd and the second relative velocity Vf based on the second wave is obtained. Then, it is assumed that the smallest received wave among those whose absolute value of the difference between the first relative velocity Vd and the second relative velocity Vf is smaller than the threshold value Vth used in the determination in the first embodiment is the reflected wave. .. Then, the determination unit 26 stores the distance based on the reflected wave and the reception time in the storage unit 22.

With the above configuration, the object detection device according to the present embodiment has the following effects in addition to the effects of the object detection device according to the first embodiment.

-Even if the received wave is an interference wave, the difference between the first relative speed Vd and the second relative speed Vf becomes small depending on the direct detection distance based on the reception timing of the received wave and the frequency of the received wave, and the reception wave is received. It may happen that the determination that the wave is not a reflected wave is not made. In this regard, in the present embodiment, the received wave is acquired a plurality of times (twice), and it is determined that the received wave having the smallest difference between the first relative velocity Vd and the second relative velocity Vf is the reflected wave. Even if the difference between the first relative velocity Vd and the second relative velocity Vf calculated based on the interference wave is smaller than a predetermined value, the received wave most likely to be the reflected wave is determined as the reflected wave. Can be done.

-In the present embodiment, since the received wave of the second wave is also acquired, even if the received wave of the first wave is an interference wave, if the received wave of the second wave is a reflected wave, 2 It is possible to perform control using the direct detection distance based on the received wave of the wave. Therefore, the reflected wave can be acquired at each transmission / reception opportunity while excluding the influence of the interference wave, and the omission of detection of the distance to the object can be suppressed.

<Sixth Embodiment>
The overall configuration of the object detection device according to the present embodiment is the same as that of the first embodiment, and processing is added to the processing executed by the object detection device according to the first embodiment.

When the storage unit 22 stores the distance and the reception time based on the received wave, the determination unit 26 stores the difference between the first relative velocity Vd and the second relative velocity Vf as the relative velocity difference in the storage unit 22.

The determination unit 26 compares the processing equivalent to that of the first embodiment, that is, the absolute value of the relative speed difference and the threshold value Vth. If the absolute value of the relative velocity difference is larger than the threshold value Vth, the information regarding the received wave is discarded as in the first embodiment.

On the other hand, when the absolute value of the relative speed difference is smaller than the threshold Vth, the relative speed difference obtained in the previous transmission / reception opportunity stored in the storage unit 22 is read out, and the relative speed difference obtained in the current transmission / reception opportunity and the previous transmission / reception opportunity are read out. Take the difference in relative speed difference obtained at the opportunity. If the absolute value of the difference between the relative speed differences is larger than a predetermined value, it is determined that the received wave is not a reflected wave, and the distance, reception time, and reception time based on the received wave acquired at this transmission / reception opportunity are determined. Discard the relative velocity difference. On the other hand, if the absolute value of the difference between the relative speed differences is equal to or less than a predetermined value, the distance, reception time, and relative speed difference based on the received wave acquired at this transmission / reception opportunity are stored in the storage unit 22. To memorize.

With the above configuration, the object detection device according to the present embodiment has the following effects in addition to the effects of the object detection device according to the first embodiment.

-At the previous transmission / reception opportunity, the first relative velocity Vd is larger than the second relative velocity Vf, and the difference is within the threshold value. At this transmission / reception opportunity, the second relative velocity Vf is greater than the first relative velocity Vd. Is also large, and the difference may be within the threshold value. In such a case, although the difference between the first relative velocity Vd and the second relative velocity Vf is within the threshold value, it indicates that one of the first relative velocity Vd and the second relative velocity Vf has changed significantly. , There is a high possibility that interference has occurred. In the present embodiment, the difference between the relative speed difference at the previous transmission / reception opportunity and the relative speed difference at the current transmission / reception opportunity is obtained, and when the difference is larger than a predetermined value, that is, the first relative speed Vd and the second. When one of the relative velocities Vf changes significantly, it is determined that the received wave is not a reflected wave, so that the received wave with a high possibility of interference wave can be appropriately excluded.

<7th Embodiment>
A part of the configuration of the object detection device according to the present embodiment is different from that of the first embodiment, and a process is added to the process executed by the object detection device according to the first embodiment.

As shown in FIG. 5, the object detection device according to the present embodiment includes a first ultrasonic sensor 10, a second ultrasonic sensor 10a, and an ECU 40.

Since the configuration of the first ultrasonic sensor 10 is the same as that of the ultrasonic sensor 10 of the first embodiment, the description thereof will be omitted. Like the first ultrasonic sensor 10, the second ultrasonic sensor 10a includes a communication unit 11a, a transmission control unit 12a, a transmission circuit 13a, a transmission / reception unit 14a, a reception circuit 15a, a distance calculation unit 16a, and a frequency calculation unit 17a. ing.

The transmission / reception unit 14 of the first ultrasonic sensor 10 and the transmission / reception unit 14a of the second ultrasonic sensor 10a are attached at intervals. This interval is an interval at which when an exploration wave is transmitted from one of the transmission / reception units 14 and 14a and the exploration wave is reflected by an object, the other transmission / reception units 14 and 14a can receive the reflected wave as a reception wave. .. Specifically, it is about several tens of cm to 1 m.

In the following, a case where the exploration wave is transmitted from the first ultrasonic sensor 10 and the reflected wave is received by the first ultrasonic sensor 10 and the second ultrasonic sensor 10a will be described. The same process is performed when the exploration wave is transmitted from the second ultrasonic sensor 10a and the reflected wave is received by the first ultrasonic sensor 10 and the second ultrasonic sensor 10a, but a specific description thereof will be omitted. ..

When the exploration wave is transmitted from the transmission / reception unit 14 of the first ultrasonic sensor 10 and the transmission / reception unit 14 of the first ultrasonic sensor 10 receives the reception wave including the reflected wave, the first ultrasonic wave is similarly to the first embodiment. The distance calculation unit 16 of the ultrasonic sensor 10 calculates the direct detection distance, which is the distance based on the difference between the transmission time of the exploration wave and the reception time of the received wave. In addition, the frequency calculation unit 17 of the first ultrasonic sensor 10 calculates the direct detection frequency, which is the frequency of the received wave, as in the first embodiment.

When the transmission / reception unit 14 of the second ultrasonic sensor 10a receives the received wave including the reflected wave, the distance calculation unit 16a of the second ultrasonic sensor 10a determines the transmission time of the exploration wave in the first ultrasonic sensor 10 and the first. 2 The indirect detection distance, which is the distance based on the difference from the reception time of the received wave in the ultrasonic sensor 10a, is calculated. In addition, the frequency calculation unit 17a of the second ultrasonic sensor 10a calculates the indirect detection frequency, which is the frequency of the received wave.

The communication unit 41 of the ECU 40 acquires the direct detection distance and the direct detection frequency from the first ultrasonic sensor 10, and acquires the indirect detection distance and the indirect detection frequency from the second ultrasonic sensor 10a.

The first relative velocity calculation unit 43 uses the direct detection distance acquired from the first ultrasonic sensor 10 and the direct detection distance in the previous transmission / reception cycle stored in the storage unit 42, and is based on the first detection distance. Find the relative velocity Vd. In addition, the first relative velocity Vd based on the indirect detection distance is obtained by using the indirect detection distance acquired from the second ultrasonic sensor 10a and the indirect detection distance in the previous transmission / reception cycle stored in the storage unit 42.

The second relative velocity calculation unit 44 calculates the second relative velocity Vf based on the direct detection frequency acquired from the first ultrasonic sensor 10. In addition, the second relative velocity Vf is calculated based on the indirect detection frequency acquired from the second ultrasonic sensor 10a.

The determination unit 46 obtains the absolute value of the difference between the first relative velocity Vd based on the direct detection distance and the second relative velocity Vf based on the direct detection frequency, and determines whether or not the value is larger than the threshold value Vth. In addition, the absolute value of the difference between the first relative velocity Vd based on the indirect detection distance and the second relative velocity Vf based on the indirect detection frequency is obtained, and it is determined whether or not the value is larger than the threshold value Vth. Then, when at least one of the absolute values is larger than the threshold value Vth, there is a possibility that an interference wave is being received, so the direct detection distance and the indirect detection distance are discarded. On the other hand, when both the absolute values are equal to or less than the threshold value, various controls using the direct detection distance and the indirect detection distance are performed, and these are stored in the storage unit 42.

As in the first embodiment, the determination unit 46 performs the above-mentioned determination process when the vehicle speed acquired from the vehicle information acquisition unit 45 is equal to or less than a predetermined value.

With the above configuration, since the object detection device according to the present embodiment also uses an indirect wave for determining whether or not interference has occurred, the accuracy of the determination can be improved.

In the present embodiment, whether or not the indirect wave is an interference wave is determined by a process according to the first embodiment, but any of the processes of the second to sixth embodiments is added. It may be a thing. Further, instead of the process according to the first embodiment, the process according to any one of the second to sixth embodiments may be used to determine whether or not the indirect wave is an interference wave.

<8th Embodiment>
The object detection device according to the present embodiment has the same overall configuration as the first to sixth embodiments, and the processes executed by the frequency calculation units 17 and 17a are different from those of the first to sixth embodiments.

The frequency calculation units 17 and 17a acquire a sine wave signal having the same phase as the exploration wave and a chord wave signal having a phase shift of π / 2 from the exploration wave. Then, the received wave is multiplied by a sine wave signal to obtain an in-phase phase component, and the received wave is multiplied by a cosine wave signal to obtain a quadrature phase component. Then, the phase of the demodulated wave is obtained based on the obtained in-phase phase component and the quadrature phase component, and the phase is set as the phase of the received wave.

The sine wave signal used to obtain the phase of the received wave has the same phase as the exploration wave, and the cosine wave signal is π / 2 out of phase with the exploration wave. Therefore, the obtained phase of the received wave is the amount of phase rotation between the probe wave and the received wave. By time-differentiating this phase rotation amount, the angular velocity ω of the difference between the phase of the exploration wave and the phase of the received wave can be obtained.

The angular velocity ω, the frequency of the exploration wave, f0, and the frequency of the received wave, f, have the relationship of the following equation (3).

この式（３）により、受信波の周波数であるｆは、既知の値である探査波の周波数であるｆ０と角速度ωを用いて、次式（４）により求められる。

According to this equation (3), f, which is the frequency of the received wave, is obtained by the following equation (4) using the known values f0, which is the frequency of the exploration wave, and the angular velocity ω.

この式（４）により求められたｆの値を第１実施形態で示した式（２）に代入することで、第２相対速度Ｖｆを求めることができる。

The second relative velocity Vf can be obtained by substituting the value of f obtained by the formula (4) into the formula (2) shown in the first embodiment.

With the above configuration, the object detection device according to the present embodiment has the same effect as each of the above embodiments.

<Modification example>
-In the first embodiment, the first relative velocity Vd and the second relative velocity Vf are compared. In this respect, the first speed and the second speed, which are the speeds of the object to be detected, may be obtained and the difference between them may be compared with the threshold value Vth. Specifically, the first speed obtained by acquiring the vehicle speed from the vehicle information acquisition unit 25 and subtracting the vehicle speed from the first relative speed Vd and the second speed obtained by subtracting the vehicle speed from the second relative speed Vf. And the difference between them and the threshold Vth may be compared.

The formula for obtaining the second relative velocity Vf shown in the first embodiment is an example, and the second relative velocity f may be obtained by another calculation method.

-A plurality of conditions for the processing according to the second to sixth embodiments may be added in combination with the processing according to the first embodiment.

-In the second to sixth embodiments, it is determined whether or not the received wave is a reflected wave by adding the conditions according to each embodiment to the processing conditions according to the first embodiment. It may be determined whether or not the received wave is a reflected wave only by any of the processes of the second to sixth embodiments. Alternatively, it may be determined that the received wave is not a reflected wave by combining a plurality of conditions of the processing according to the second to sixth embodiments without performing the processing according to the first embodiment.

In the seventh embodiment, the absolute value of the difference between the first relative velocity Vd based on the direct detection distance and the second relative velocity Vf based on the direct detection frequency is smaller than a predetermined value, and the first relative velocity is based on the indirect detection distance. If the absolute value of the difference between the relative velocity Vd and the second relative velocity Vf based on the indirect detection frequency is larger than the predetermined value, the indirect detection distance is discarded, various controls using the direct detection distance, and direct The detection distance may be stored. Similarly, the absolute value of the difference between the first relative velocity Vd based on the direct detection distance and the second relative velocity Vf based on the direct detection frequency is larger than the predetermined value, and the first relative velocity Vd based on the indirect detection distance If the absolute value of the difference from the second relative velocity Vf based on the indirect detection frequency is smaller than the predetermined value, the direct detection distance is discarded, various controls using the indirect detection distance, and storage of the direct detection distance are stored. May be done.

-In each embodiment, the frequency of the received wave is used to obtain the first relative velocity Vd, but the first relative velocity Vd may be obtained by using a period that is the reciprocal of the frequency. This period can also be referred to as wave characteristics because it shows the characteristics of the received wave as well as the frequency.

-In each embodiment, the distance calculation unit 16, the frequency calculation unit 17, and the like are provided in the ultrasonic sensor 10, and the storage units 22, 32, 42, the first relative speed calculation unit 23, 33, 43, and the second relative speed calculation unit are provided. 24, 34, 44, determination units 26, 38, 46 and the like are provided in the ECUs 20, 30 and 40. In this respect, the functions provided in the ultrasonic sensor 10 and the functions provided in the ECUs 20, 30, and 40 are not limited to those shown in the embodiments, and can be changed. Further, in each embodiment, the ultrasonic sensor 10 and the ECUs 20, 30 and 40 are connected via a communication line, but the ECU 30 is not provided and the ultrasonic sensor 10 is provided with each function of the ECUs 20, 30 and 0. May be provided.

-In each embodiment, the object detection device including the ultrasonic sensor 10 and the ECUs 20, 30, and 40 is mounted on the vehicle, but it may be mounted on a moving body other than the vehicle.

-The processing according to each embodiment can be executed not only while the vehicle is moving but also when the vehicle is stopped. In this case, when an object exists in front of the vehicle in the traveling direction, control or the like for restricting the start of the vehicle may be performed.

-In each embodiment, an object detection device including an ultrasonic sensor 10 and ECUs 20, 30, and 40 is mounted on a movable vehicle, but an object detection device is provided on a road structure or the like. It may be used to detect an object moving in the surroundings.

14 ... Transmission / reception unit, 14a ... Transmission / reception unit, 16 ... Distance calculation unit, 16a ... Distance calculation unit, 23 ... First relative speed calculation unit, 24 ... Second relative speed calculation unit, 26 ... Judgment unit, 33 ... First relative Velocity calculation unit, 34 ... 2nd relative velocity calculation unit, 35 ... 1st relative acceleration calculation unit, 36 ... 2nd relative acceleration calculation unit, 38 ... judgment unit, 43 ... 1st relative velocity calculation unit, 44 ... second relative Speed calculation unit, 46 ... Judgment unit.

Claims (10)

An object detection device that transmits exploration waves at predetermined transmission / reception opportunities, acquires received waves including reflected waves from surrounding objects, and detects the object.
A transmitter / receiver (14) that transmits the exploration wave and receives the received wave, and
A distance calculation unit (16) that calculates a direct detection distance indicating a distance to the object based on the transmission time of the exploration wave and the reception time of the received wave.
The first relative speed calculation unit (23) that obtains the relative speed with the object as the first relative speed based on the direct detection distance calculated at the current transmission / reception opportunity and the direct detection distance acquired at the previous transmission / reception opportunity. , 33, 43),
A second relative that obtains the relative velocity with the object as the second relative velocity based on the wave characteristic that is the frequency or period of the exploration wave and the wave characteristic of the received wave received at this transmission / reception opportunity. With the speed calculation unit (24, 34, 44),
When the difference between the first relative velocity and the second relative velocity is larger than a predetermined value, the determination unit (26,) determines that the received wave received at this transmission / reception opportunity is not the reflected wave of the exploration wave. and 38, 46), equipped with a,
The determination unit obtains the difference between the first relative speed and the second relative speed as the relative speed difference for each transmission / reception opportunity, and obtains the relative speed difference in the previous transmission / reception opportunity and the relative speed difference in the current transmission / reception opportunity. An object detection device that determines that the received wave received at this transmission / reception opportunity is not a reflected wave even when the difference between the two is larger than a predetermined value . An acceleration acquisition unit (37) mounted on a moving body and acquiring the acceleration of the moving body,
The first relative acceleration calculation unit (35) that obtains the relative acceleration with the object as the first relative acceleration based on the first relative velocity, and the second relative acceleration with the object based on the second relative velocity. Further provided with at least one of the second relative acceleration calculation unit (36) obtained as the relative acceleration.
In the determination unit (38), at least one of the sum of the first relative acceleration and the acceleration of the moving body and the sum of the second relative acceleration and the acceleration of the moving body is larger than a predetermined value. The object detection device according to claim 1, further conditioned on the fact that the received wave received at this transmission / reception opportunity is determined not to be a reflected wave of the exploration wave. The first relative acceleration calculation unit (35), which obtains the relative acceleration with the object as the first relative acceleration based on the first relative velocity,
Further, a second relative acceleration calculation unit (36) for obtaining the relative acceleration with the object as the second relative acceleration based on the second relative velocity is provided.
The determination unit (38) further compares the first relative acceleration and the second relative acceleration, and on the condition that the difference is larger than a predetermined value, the received wave received at this transmission / reception opportunity The object detection device according to claim 1, further determining that the wave is not a reflected wave. An object detection device that transmits exploration waves at predetermined transmission / reception opportunities, acquires received waves including reflected waves from surrounding objects, and detects the object.
A transmitter / receiver (14) that transmits the exploration wave and receives the received wave, and
A distance calculation unit (16) that calculates a direct detection distance indicating a distance to the object based on the transmission time of the exploration wave and the reception time of the received wave.
The first relative speed calculation unit (23) that obtains the relative speed with the object as the first relative speed based on the direct detection distance calculated at the current transmission / reception opportunity and the direct detection distance acquired at the previous transmission / reception opportunity. , 33, 43),
A second relative that obtains the relative velocity with the object as the second relative velocity based on the wave characteristic that is the frequency or period of the exploration wave and the wave characteristic of the received wave received at this transmission / reception opportunity. With the speed calculation unit (24, 34, 44),
When the difference between the first relative velocity and the second relative velocity is larger than a predetermined value, the determination unit (26,) determines that the received wave received at this transmission / reception opportunity is not the reflected wave of the exploration wave. 38,46) and
The first relative acceleration calculation unit (35), which obtains the relative acceleration with the object as the first relative acceleration based on the first relative velocity,
Further, a second relative acceleration calculation unit (36) for obtaining the relative acceleration with the object as the second relative acceleration based on the second relative velocity is provided.
The determination unit (38) further compares the first relative acceleration and the second relative acceleration, and on the condition that the difference is larger than a predetermined value, the received wave received at this transmission / reception opportunity An object detection device that further determines that it is not the reflected wave. Acquire a plurality of the received waves for the transmission of the exploration wave of one transmission / reception opportunity,
The first relative velocity calculation unit calculates the first relative velocity for each received wave.
The second relative velocity calculation unit calculates the second relative velocity for each received wave.
The determination unit compares the first relative velocity and the second relative velocity for each received wave, and the difference between the first relative velocity and the second relative velocity is smaller than the predetermined value, and The object detection device according to any one of claims 1 to 4 , wherein the received wave having the smallest difference between the first relative velocity and the second relative velocity is determined to be the reflected wave. A receiving unit (14a) provided so as to be able to receive a received wave including a reflected wave of the exploration wave transmitted from the transmitting / receiving unit is further provided.
The distance calculation unit (16a) further calculates an indirect detection distance indicating the distance to the object based on the transmission time of the exploration wave and the reception time of the received wave received by the reception unit.
The first relative velocity calculation unit (43) further calculates the first relative velocity based on the frequency of the received wave received by the reception unit.
The second relative speed calculation unit (44) further calculates the second relative speed based on the indirect detection distance.
In the determination unit (46), the difference between the first relative velocity and the second relative velocity based on the received wave received by the transmission / reception unit is within a predetermined value, and the reception unit receives the reception. When the difference between the first relative velocity and the second relative velocity based on the received wave is within a predetermined value, the received wave received by the receiving unit at this transmission / reception opportunity is the reflected wave of the exploration wave. The object detection device according to any one of claims 1 to 5 , which is determined to be present. The object detection device according to any one of claims 1 to 6 , wherein the determination unit makes the determination when its own moving speed is smaller than a predetermined speed. The wave characteristics include frequency
Any of claims 1 to 7 , further comprising a frequency calculation unit (17) that calculates the frequency of the received wave based on the frequency of the exploration wave and the angular velocity of the phase rotation of the exploration wave and the received wave. The object detection device according to item 1. An object detection device that transmits exploration waves at predetermined transmission / reception opportunities, acquires received waves including reflected waves from surrounding objects, and detects the object.
The transmission unit (14) that transmits the exploration wave and
The receiving unit (14a) that receives the received wave and
A distance calculation unit (16a) that calculates an indirect detection distance indicating the distance to the object based on the transmission time of the exploration wave and the reception time of the received wave.
The first relative speed calculation unit (43) that obtains the relative speed with the object as the first relative speed based on the indirect detection distance calculated at the current transmission / reception opportunity and the indirect detection distance acquired at the previous transmission / reception opportunity. )When,
A second relative that obtains the relative velocity with the object as the second relative velocity based on the wave characteristic that is the frequency or period of the exploration wave and the wave characteristic of the received wave received at this transmission / reception opportunity. With the speed calculation unit (44)
When the difference between the first relative velocity and the second relative velocity is larger than a predetermined value, the determination unit (46) determines that the received wave received at this transmission / reception opportunity is not the reflected wave of the exploration wave. and, with a,
The first relative acceleration calculation unit (35), which obtains the relative acceleration with the object as the first relative acceleration based on the first relative velocity,
Further, a second relative acceleration calculation unit (36) for obtaining the relative acceleration with the object as the second relative acceleration based on the second relative velocity is provided.
The determination unit (38) further compares the first relative acceleration and the second relative acceleration, and further conditions that the difference is larger than a predetermined value, the received wave received at this transmission / reception opportunity. Is an object detection device that determines that is not the reflected wave . An object detection device that transmits exploration waves at predetermined transmission / reception opportunities, acquires received waves including reflected waves from surrounding objects, and detects the object.
The transmission unit (14) that transmits the exploration wave and
The receiving unit (14a) that receives the received wave and
A distance calculation unit (16a) that calculates an indirect detection distance indicating a distance to the object based on the transmission time of the exploration wave and the reception time of the received wave.
The first relative speed calculation unit (43) that obtains the relative speed with the object as the first relative speed based on the indirect detection distance calculated at the current transmission / reception opportunity and the indirect detection distance acquired at the previous transmission / reception opportunity. )When,
A second relative that obtains the relative velocity with the object as the second relative velocity based on the wave characteristic that is the frequency or period of the exploration wave and the wave characteristic of the received wave received at this transmission / reception opportunity. Speed calculation unit (44) and
When the difference between the first relative velocity and the second relative velocity is larger than a predetermined value, the determination unit (46) determines that the received wave received at this transmission / reception opportunity is not the reflected wave of the exploration wave. And with
The determination unit obtains the difference between the first relative speed and the second relative speed as the relative speed difference for each transmission / reception opportunity, and obtains the relative speed difference in the previous transmission / reception opportunity and the relative speed difference in the current transmission / reception opportunity. An object detection device that determines that the received wave received at this transmission / reception opportunity is not a reflected wave even when the difference between the two is larger than a predetermined value.

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