JP6933986B2 - Target detection device, target detection method and program - Google Patents

Description

The present invention relates to a target detection device, a target detection method, and a program.

A radar device is used as a means for monitoring the surroundings of a vehicle in order to prevent a collision with a target existing around the vehicle or to realize automatic driving (for example, Patent Document 1). The optical axis of the radar transmitted by the radar device may deviate due to the mounting accuracy when the radar device is mounted on the vehicle, or the secular change due to the vehicle running after the mounting.

The radar device described in Patent Document 1 detects the relative speed and azimuth angle between the vehicle and the target with respect to such a deviation of the optical axis of the radar, and utilizes the azimuth angle dependence of the relative speed with respect to the target. Therefore, the amount of deviation of this optical axis is calculated.

Japanese Unexamined Patent Publication No. 2002-228479

However, the radar device of Patent Document 1 needs to detect the relative speed between the vehicle and the target in order to utilize the azimuth-angle dependence of the relative speed with respect to the target, and the detection accuracy of the relative speed, that is, the detection is performed. Since the relative velocity error itself affects the calculation result of the deviation amount of the optical axis, there is a problem that the calculation accuracy of the deviation amount of the optical axis is not sufficient.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a target detection device or the like capable of accurately deriving an azimuth angle with a detected target.

The target detection device according to one aspect of the present disclosure is a target detection device mounted on a vehicle and detecting a target existing in the vicinity of the vehicle, and derives an azimuth angle between the target and the own vehicle. The azimuth angle deriving unit, the first distance between the target and the own vehicle, and the distance for deriving the second distance between the target and the own vehicle, which exists in a direction substantially perpendicular to the traveling direction of the own vehicle. A derivation unit and a correction angle derivation unit for deriving a correction angle for correcting the azimuth angle based on the first distance and the second distance are provided, and a target of the first distance and the second distance are provided. The target is a stationary object that exists parallel to the traveling direction of the own vehicle, and the transmitted wave transmitted from the radar device mounted on the own vehicle is reflected as a reflected wave from the stationary object to detect the target. The unit detects a reflection point based on the received reflected wave, and the distance derivation unit derives a first distance between the own vehicle and the reflection point and is positioned in a direction perpendicular to the traveling direction of the own vehicle. The second distance between the reflection point of the stationary object and the own vehicle is derived, and the azimuth angle derivation unit derives the first azimuth angle between the own vehicle and the reflection point, and the first distance and the first The second azimuth angle between the own vehicle and the ideal point is derived based on the two distances, and the correction angle deriving unit derives the difference between the first azimuth angle and the second azimuth angle as a correction angle.

In this aspect, the correction for the azimuth angle is based on the first distance between the target and the own vehicle and the second distance between the target and the own vehicle that exists in a direction substantially perpendicular to the traveling direction of the own vehicle. Derived the angle. Therefore, in deriving the correction angle, the relative speed between the target and the own vehicle is not required, the correction angle can be derived with good accuracy, and the azimuth angle can be corrected by the correction angle.

In the target detection device according to one aspect of the present disclosure, the correction angle deriving unit derives the correction angle based on the difference between the angle derived by the first distance and the second distance and the azimuth angle. ..

In this embodiment, the correction angle deriving unit derives the correction angle based on the difference between the angles derived by the first distance and the second distance and the azimuth, so that the correction angle is derived with high accuracy. be able to.

The target detection device according to one aspect of the present disclosure derives a correction angle for each azimuth angle derived by the azimuth angle deriving unit, and stores the azimuth angle and the derived correction angle in association with each other. It has a part.

In this embodiment, in order to store each of the azimuth angles and the derived correction angle in the storage unit in association with each other, each azimuth angle is corrected by the correction angle for each azimuth angle, and the accuracy of the corrected azimuth angle is obtained. Can be improved.

In the target detection device according to one aspect of the present disclosure, after the correction angle is stored in the storage unit, the correction angle deriving unit derives a correction angle having the same azimuth as the azimuth corresponding to the correction angle. If so, the storage unit is provided with an update unit that updates the correction angle stored in the storage unit.

In this embodiment, after the correction angle is stored in the storage unit, when the correction angle deriving unit derives a correction angle having the same azimuth as the azimuth corresponding to the correction angle, the correction angle is updated. Therefore, the latest correction angle can be secured.

In the target detection device according to one aspect of the present disclosure, the update unit derives the correction angle already stored in the storage unit and the correction angle derivation unit after the correction angle is stored in the storage unit. The correction angle stored in the storage unit is updated based on the corrected correction angle.

In this embodiment, the correction angle already stored in the storage unit and the correction angle derived by the correction angle derivation unit after the correction angle is stored in the storage unit are stored in the storage unit. Since the correction angle is updated, it is possible to prevent the correction angle from being excessively changed due to the update.

When the target detection device according to one aspect of the present disclosure derives the second distance by a predetermined number or more within a predetermined period during the traveling of the own vehicle, the correction angle deriving unit performs the first distance and the predetermined number. Based on the second distance derived from the number or more, the correction angle with respect to the azimuth angle is derived.

In this embodiment, when a predetermined number or more of the second distances are derived within a predetermined period during the traveling of the own vehicle, the first distance and the second distances of the objects drifting detected a plurality of times are used as the basis. Since the correction angle with respect to the azimuth angle is derived, the correction angle can be derived with high accuracy.

In the target detection device according to one aspect of the present disclosure, the correction angle deriving unit has a correction angle with respect to the azimuth angle based on the average value or standard deviation of the first distance and the second distance derived from the predetermined number or more. Is derived.

In the target detection method according to one aspect of the present disclosure, the correction angle deriving unit derives a correction angle with respect to the azimuth angle based on the average value of the first distance and the second distance derived by a predetermined number or more. Therefore, it is possible to eliminate the variation in the second distance of each object and derive the correction angle with high accuracy.

The target detection method according to one aspect of the present disclosure derives the azimuth angle between the target detected as existing in the vicinity of the own vehicle and the own vehicle, the first distance between the target and the own vehicle, and To derive a second distance between a target existing in a direction substantially perpendicular to the traveling direction of the own vehicle and the own vehicle, and to correct the azimuth angle based on the first distance and the second distance. Derivation of the correction angle of.

In this embodiment, it is possible to provide a target detection method that eliminates the need for the relative speed between the target and the own vehicle in deriving the correction angle, derives the correction angle with good accuracy, and corrects the azimuth angle by the correction angle. can.

The program according to one aspect of the present disclosure derives to a computer the azimuth angle between the target and the own vehicle detected as existing in the vicinity of the own vehicle, the first distance between the target and the own vehicle, and To derive a second distance between a target existing in a direction substantially perpendicular to the traveling direction of the own vehicle and the own vehicle, and to correct the azimuth angle based on the first distance and the second distance. The process of deriving the correction angle of is executed.

In this aspect, the computer can function as a target detection device.

It is possible to provide a target detection device or the like that accurately derives the azimuth angle with the detected target.

It is a schematic diagram which shows an example of the vehicle which includes the target detection device which concerns on Embodiment 1. FIG. It is a block diagram which shows the structure of the target detection apparatus which concerns on Embodiment 1. FIG. It is explanatory drawing about the difference between the detected drifting (reflection point) and the actual drifting (ideal point). It is explanatory drawing about the derivation of a correction angle. It is explanatory drawing about the comparison between the detected drift (reflection point) and the drift based on the corrected azimuth. It is explanatory drawing about correspondence (table) with azimuth angle and correction angle. It is a flowchart which shows the processing outline about the target detection. It is a flowchart which shows the process of the control part which concerns on Embodiment 1 (basic form). It is a flowchart which shows the process of the control part which concerns on Embodiment 2 (update).

(Embodiment 1)
Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 is a schematic view showing an example of a vehicle 1 including the target detection device 3 according to the first embodiment. FIG. 2 is a block diagram showing the configuration of the target detection device 3 according to the first embodiment. The vehicle 1 includes a front bumper 11, a rear bumper 12, a vehicle body frame 10, and a target detection device 3 including a radar device 4 and a radar ECU (Electronic Control Unit) 5.

Radar devices 4 are provided at the front and rear corners of the vehicle 1. The front and rear corners of the vehicle 1 include the front bumper 11, the rear bumper 12, and the body frame 10.

The radar devices 4 are provided at the left and right corners of the front bumper 11 and the rear bumper 12, respectively. Corresponding radar ECUs 5 are connected to each of the radar devices 4, and each of these radar ECUs 5 is connected to the body ECU 6 by an in-vehicle LAN (Local Area network) 2 described later.

The horizontal transmission angle (θFL) of the radar device 4 provided at the left corner of the front bumper 11 is set to be 90 ° or more. Similarly, the horizontal transmission angles (θFR, θBL, θBR) of each of the radar devices 4 provided at the right corner of the front bumper 11 and the left and right corners of the rear bumper 12 should be 90 ° or more. It has been set. The direction of the radar device 4 is such that the transmission range of the radio wave transmitted from the radar device 4 is directly lateral to the outside of the vehicle 1 from each of the radar devices 4, that is, substantially perpendicular to the outside with respect to the traveling direction of the vehicle 1. It is set to include the direction. Therefore, when the forward direction of the vehicle 1 when traveling straight is 90 °, the transmission range of the radar device 4 provided on the right side of the front bumper 11 is from approximately 335 ° (-25 °) to approximately 115 ° in the horizontal direction. including. The transmission range of the radar device 4 provided on the left side of the front bumper 11 includes a direction of approximately 65 ° to approximately 205 ° in the horizontal direction. The transmission range of the radar device 4 provided on the left side of the rear bumper 12 includes a direction of about 155 ° to about 295 ° in the horizontal direction. The transmission range of the radar device 4 provided on the right side of the rear bumper 12 includes a direction of approximately 245 ° to approximately 25 ° (385 °) in the horizontal direction. That is, when the transmission angle (θFL, θFR, θBL, θBR) of each of the radar devices 4 is 140 °, ± 70 in the horizontal direction from this optical axis with reference to the center line (optical axis) which is half of the transmission angle. Radio waves (transmitted waves) are transmitted from each of the radar devices 4 within the range of °. The installation location of the radar device 4 is described as the front and rear corners of the vehicle 1, but the installation location is not limited to this. The radar device 4 may be installed at the center of the left and right sides of the vehicle 1 or at the center of the front and rear.

The radar device 4 includes a transmitting unit 41, a transmitting antenna 42, a receiving unit 43, and a receiving antenna 44. The transmission unit 41 is connected to the radar ECU 5 via an input / output interface 54 described later, and transmits radio waves (transmitted waves) based on a signal from the control unit 51 of the radar ECU 5 described later. The transmitted wave is, for example, a radio wave in the millimeter wave band of 30 GHz to 300 GHz. Alternatively, it is a radio wave in the microwave frequency band of 10 GHz to 30 GHz.

The transmitting antenna 42 is a directional antenna having a transmitting direction of a transmitted wave, that is, a directivity, and a transmitting range is set in the horizontal direction as described above, and the transmitting range is for detecting a target described later. It becomes the detection range. The transmitting antenna 42 is connected to the transmitting unit 41, and transmits radio waves (transmitted waves) from the transmitting unit 41 by output.

The receiving antenna 44 is connected to the receiving unit 43 and is arranged so as to face substantially the same direction as the transmitting antenna 42. The receiving antenna 44 receives the reflected wave reflected by the target and outputs it to the receiving unit 43.

The receiving unit 43 is connected to the radar ECU 5 via an input / output interface 54 described later, and acquires the reflected wave reflected by the target via the receiving antenna 44. The target includes, for example, other vehicles traveling around the own vehicle, equipment provided on the side edge of the road, pedestrians, and the like. The receiving unit 43 converts the acquired reflected wave into, for example, A / D and outputs it to the control unit 51.

When the radar device 4 uses, for example, the FMCW method (Frequency Modulated Continuous Wave), the transmitting unit 41 transmits a radio wave (transmitted wave) whose frequency changes in proportion to time, and the receiving unit 43 is a target. Receives a beat signal that is a mixture of the reflected wave and the transmitted wave reflected by.

The radar ECU 5 includes a control unit 51, a storage unit 52, a communication unit 53, and an input / output interface 54. The control unit 51 is composed of a CPU (Central Processing Unit), an MPU (Micro Processing Unit), or the like, and various control processes and various control processes can be performed by reading and executing a control program and data stored in advance in the storage unit 52. It is designed to perform arithmetic processing and the like. The control unit 51 functions as a target detection unit, a distance derivation unit, an azimuth angle derivation unit, a correction angle derivation unit, an update unit, and a determination unit by executing a control program stored in the storage unit 52.

The target detection unit transmits a radio wave (transmitted wave) whose frequency changes in proportion to time by using a known method such as the FMCW method, and transmits the reflected wave reflected by the target. The target is detected by receiving.

For example, in the case of the FMCW method, the distance derivation unit receives a beat signal in which a transmitted wave and a reflected wave are mixed, analyzes the frequency of the beat signal by performing an FFT analysis (Fast Fourier Transform) on the beat signal, and analyzes the frequency of the beat signal. Based on the analysis result of, the distance between the own vehicle and the target is derived.

The azimuth angle deriving unit analyzes the phase of the beat signal and derives the azimuth angle with respect to the target with respect to the own vehicle based on the analysis result of the phase.

The correction angle derivation unit will be described in detail later, but the distance between the target (a part of a stationary object) derived by the distance derivation unit and the own vehicle with respect to the azimuth angle of the target derived by the azimuth angle derivation unit. And the correction angle is derived based on the distance in the direction perpendicular to the stationary object with respect to the traveling direction of the own vehicle.

Although the details will be described later, the updating unit updates the correction angle derived by the correction angle deriving unit and already stored in the storage unit with the newly derived correction angle.

Although the details will be described later, the determination unit determines the progress of the own vehicle based on the distance between the plurality of targets detected within a predetermined period and the direction perpendicular to the traveling direction of the own vehicle. Determine if it is part of a stationary object that exists parallel to the direction.

Even if the receiving unit 43 of the radar device 4 has computing power such as Fourier transform and functions as a target detection unit, a distance derivation unit, an azimuth angle derivation unit, a correction angle derivation unit, an update unit, or a determination unit. good. Alternatively, the receiving unit 43 of the radar device 4 and the control unit 51 of the radar ECU 5 cooperate to function as a target detection unit, a distance derivation unit, an azimuth angle derivation unit, a correction angle derivation unit, an update unit, or a determination unit. You may. Alternatively, the control unit 61 of the body ECU 6, which will be described later, executes a control program and communicates with and controls the radar device 4 or the control unit 51 of the radar ECU 5, or cooperates with the target detection unit, the distance derivation unit, and the azimuth. It may function as an angle derivation unit, a correction angle derivation unit, an update unit, or a determination unit.

The storage unit 52 is composed of a volatile memory element such as a RAM (Random Access Memory) or a non-volatile memory element such as a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable ROM) or a flash memory. The control program and the data to be referred to during processing are stored in advance. The control program stored in the storage unit 52 may be a control program read from a recording medium (not shown) readable by the target detection device 3. Further, the control program may be downloaded from an external computer (not shown) connected to a communication network (not shown) and stored in the storage unit 52. Although the details will be described later, the storage unit 52 stores each azimuth angle and the correction angle corresponding to each azimuth angle.

The communication unit 53 is a communication interface using a communication protocol such as CAN (Control Area Network), LIN (Local Interconnect Network) or Ethernet (registered trademark), and is connected to an in-vehicle device such as a body ECU 6 connected to an in-vehicle LAN 2. Communicate with each other.

The input / output interface 54 is connected to the transmission unit 41 and the reception unit 43 of the radar device 4 by a serial cable or the like, and data is input / output between the control unit 51 and the transmission unit 41 and the reception unit 43. It is an interface.

The target detection device 3 describes the radar device 4 and the radar ECU 5 as separate bodies, but the target detection device 3 is not limited thereto. The radar device 4 and the radar ECU 5 may be, for example, a modularized and integrated target detection device 3.

The vehicle 1 is provided with in-vehicle devices such as a vehicle speed detection unit 7 and a notification unit 8, and the in-vehicle devices such as the notification unit 8 are provided via, for example, a body ECU 6 and an input / output interface 64 included in the body ECU 6. It is connected.

Like the radar ECU 5, the body ECU 6 includes a control unit 61, a storage unit 62, a communication unit 63, and an input / output interface 64. The control unit 61 is composed of a CPU (Central Processing Unit), an MPU (Micro Processing Unit), or the like, and can perform various control processes by reading and executing a control program and data stored in advance in the storage unit 62. It is designed to perform arithmetic processing and the like.

The storage unit 62 is composed of a volatile memory element such as a RAM (Random Access Memory) or a non-volatile memory element such as a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable ROM) or a flash memory. The control program and the data to be referred to during processing are stored in advance.

The communication unit 63 is a communication interface using a communication protocol such as CAN (Control Area Network), LIN (Local Interconnect Network) or Ethernet (registered trademark), and is connected to an in-vehicle device such as a radar ECU 5 connected to the in-vehicle LAN 2. Communicate with each other.

The input / output interface 64 is a group of interfaces for connecting to in-vehicle devices such as the vehicle speed detection unit 7 and the notification unit 8 by a serial cable or the like and inputting / outputting data between the control unit 61 and these in-vehicle devices. ..

The vehicle speed detection unit 7 is a vehicle speed sensor composed of, for example, a Hall element, etc., detects the traveling speed (vehicle speed) of the vehicle 1, and outputs data related to the detected vehicle speed to the body ECU 6 via the input / output interface 64. do.

The notification unit 8 is composed of, for example, a speaker or a display, is connected to the body ECU 6 via the input / output interface 64, and displays a warning regarding a target located around the vehicle 1 based on the output from the body ECU 6. Alternatively, a voice output is performed to notify the operator of the vehicle 1.

The output from the body ECU 6 includes an output obtained by the body ECU 6 from the radar ECU 5 and output, that is, an output from the radar ECU 5 to the notification unit 8 by the body ECU 6 relaying the output. In the present embodiment, the vehicle speed detection unit 7 and the notification unit 8 are connected to the input / output interface 64 of the body ECU 6, but the present invention is not limited to this. The vehicle speed detection unit 7 and the notification unit 8 may be connected to the input / output interface 54 of the radar ECU 5 and input / output may be directly performed with the radar ECU 5. Alternatively, the vehicle speed detection unit 7 and the notification unit 8 are connected to other ECUs other than the body ECU 6 and the radar ECU 5, and the radar ECU 5 communicates with the other ECUs to input and output between the vehicle speed detection units 7 and the like. May be done.

FIG. 3 is an explanatory diagram showing the difference between the detected drift (reflection point) and the actual drift (ideal point). The target detection device 3 reflects the transmitted transmitted wave and detects the target by receiving the reflected wave. The target is detected as being present at the reflection point where the transmitted wave is reflected.

For example, when a stationary object such as a guardrail or a wall existing parallel to the traveling direction of the vehicle 1 reflects the transmitted wave transmitted from the radar device 4 of the target detection device 3 mounted on the vehicle 1, the reflection thereof. Ideally, the plurality of reflection points due to the above should be detected so as to be aligned in a straight line on a stationary object such as a guardrail as shown in FIG. 3A.

However, the reflection point detected by the control unit 51 of the radar ECU 5 may be detected laterally from a stationary object such as a guardrail as shown in FIG. 3B. As a factor for detecting the position (coordinates) of the reflection point shifted to the left and right from the stationary object, for example, when the radar device 4 is mounted on the vehicle 1, the optical axis of the radar device 4 is originally mounted. It is considered that the position is deviated and the transmission direction of the transmitted wave from the radar device 4 is deviated. Alternatively, when the radar device 4 is provided at a corner of a bumper or the like, the transmitted wave transmitted from the radar device 4 is affected by reflection or refraction by the bumper or the like, and the transmission angle of the transmitted wave deviates. Or, it is conceivable that the transmission angle varies when the transmitted wave passes through the bumper or the like and is transmitted to the outside of the vehicle 1.

FIG. 4 is an explanatory diagram relating to the derivation of the correction angle. FIG. 5 is an explanatory diagram relating to a comparison between the detected drift (reflection point) and the drift based on the corrected azimuth angle. FIG. 6 is an explanatory diagram regarding the correspondence (table) with the azimuth angle and the correction angle. In the explanatory views of FIGS. 4 and 5, the traveling direction of the vehicle 1 (own vehicle) is described as the X-axis, and the direction perpendicular to the traveling direction is described as the Y-axis.

The control unit 51 of the radar ECU 5 detects the reflection point based on the received reflected wave when detecting the target, and derives the distance (l) and the azimuth angle (θd) between the own vehicle and the reflection point. The control unit 51 derives a distance (gr_y [m]) in the direction perpendicular to the traveling direction (Y-axis direction) of the own vehicle and a stationary object such as a guardrail. In this case, a part such as a guardrail located in the direction perpendicular to the traveling direction of the own vehicle is also detected as a reflection point. The azimuth angle between the reflection point and the own vehicle is 180 ° when the traveling direction is 90 ° as shown in FIG. When detecting a reflection point located in the direction perpendicular to the traveling direction of the own vehicle in this way, the relative speed between the reflection point and the own vehicle momentarily becomes 0 km / h, and the Doppler effect does not occur, that is, the transmitted wave. And the received reflected wave have almost the same frequency. Since the detection of the reflection point in the state where the Doppler effect does not occur is relatively accurate, it can be used in the derivation of the correction angle described later. The angle between the reflection point for deriving the distance (gr_y [m]) in the direction perpendicular to the traveling direction of the own vehicle (Y-axis direction) and the traveling direction of the own vehicle must be strictly 90 °. However, it may be within an acceptable range in deriving the correction angle, and may be, for example, about ± 3 ° or less with respect to 90 °.

The control unit 51 of the radar ECU 5 determines the distance (gr_y [m]) between the vehicle and a stationary object such as a guard rail in the direction perpendicular to the traveling direction of the vehicle (Y-axis direction) and the distance between the detected reflection points (gr_y [m]). Based on l [m]), the azimuth angle (θi) between the own vehicle and the ideal point is derived. The ideal point means the position (coordinates) of the reflection point that should be originally detected.

To derive the azimuth angle (θi) from the ideal point, for example, the distance (l [m]) from the detected reflection point is set as the hypotenuse, and the direction perpendicular to the traveling direction of the own vehicle and the stationary object (Y). It can be derived by calculating the angle (θi) between the hypotenuse and the opposite side (θi = arcsin (gr_y / l)) in a right triangle whose opposite side is the distance (gr_y [m]) in the axial direction. The angle (θi) is defined as the original azimuth angle (assumed azimuth angle) between the target (reflection point) that should be located on a stationary object and the own vehicle. The control unit 51 calculates the difference between the derived assumed azimuth angle (θi), that is, the azimuth angle of the ideal point (θi) and the azimuth angle of the detected reflection point (θd) (θi-θd), and calculates the difference. Derived as a correction angle.

As shown in FIG. 5, the control unit 51 detects a plurality of reflection points on a stationary object such as a guardrail that exists parallel to the traveling direction of the vehicle 1. Each detected reflection point is recognized as a target, and each of these targets is a part such as a guardrail which is a stationary object. The control unit 51 detects a plurality of reflection points, derives a distance and an azimuth angle from the own vehicle at each reflection point, and derives a correction angle for each of these azimuth angles as described above. FIG. 5A shows the distribution of the coordinates of the detected target (reflection point), and FIG. 5B shows the distribution of the coordinates of the target (reflection point) after the azimuth angle is corrected by the derived correction angle. Compared with FIG. 5A before the correction, in FIG. 5B after the correction, the left-right variation of the reflection point with respect to the guardrail is reduced, and the detection accuracy of the reflection point, that is, the target is improved.

The control unit 51 stores the corrected angles for each of the derived azimuth angles in the storage unit 52 in association with the azimuth angles and the corresponding correction angles in a table format (correction angle table) as shown in FIG. 6, for example. For example, the control unit 51 refers to the correction angle table stored in the storage unit 52, reads out the correction angle corresponding to the azimuth angle with respect to the detected azimuth angle of the target, and corrects it by the correction angle. Let the azimuth be the true azimuth of the target. Based on this true azimuth, the control unit 51 performs various processes such as collision prediction processing with the target and output processing of information about the target to the body ECU 6.

The control unit 51 has already stored the correction angle corresponding to the azimuth angle, and when a correction angle corresponding to the azimuth angle is newly derived thereafter, the newly derived correction angle corresponds to the azimuth angle. The correction angle to be used may be updated.

When the derived azimuth angle is not stored in the storage unit 52, the control unit 51 derives the corrected azimuth angle of the derived azimuth angle based on the correction angle of another azimuth angle that is close to the derived azimuth angle. You may. For example, when the derived azimuth angle is 68.5 °, the average value of the correction angles of 68 ° and 69 °, which are the closest approximate values when the azimuth angle is increased or decreased from the derived azimuth angle, is derived. It may be a correction angle of the azimuth.

With respect to the azimuth angle of the target (reflection point) detected as a part of a stationary object existing parallel to the traveling direction of the vehicle 1, the distance between the reflection point and the own vehicle and the direction perpendicular to the traveling direction of the own vehicle. The true azimuth (assumed azimuth) with respect to the reflection point can be derived based on the distance to the stationary part located in.

By deriving each correction angle corresponding to each azimuth based on the difference between the derived assumed azimuth angle and the detected azimuth angle, each azimuth angle can be appropriately corrected, and a target (reflection point) can be corrected. ) Can be improved in detection accuracy.

Since each of the derived correction angles is stored in the storage unit 52 in association with each corresponding azimuth angle, in order to correct the detected azimuth angle, the correction angle corresponding to the azimuth angle is referred to with reference to the storage unit 52. It can be a simple process of reading out, and the processing time required for correcting the azimuth can be shortened.

Even if the correction angle corresponding to the azimuth angle is already stored in the storage unit 52, it is already stored when the correction angle is newly derived by a stationary object existing parallel to the traveling direction of the vehicle 1. Since the correction angle is updated, the freshness or reliability of the correction angle can be guaranteed.

FIG. 7 is a flowchart showing an outline of processing related to target detection. The control unit 51 of the radar ECU 5 constantly executes the following processing in a state where the IG switch (ignition) of the vehicle is on.

The control unit 51 creates a detection point list (S01). The transmitted wave transmitted from the transmitting unit 41 based on the instruction from the control unit 51 is reflected by the target. There may be a plurality of reflection points where this reflection occurs in a single target. The control unit 51 acquires the reflected wave reflected by the plurality of reflection points via the reception unit 43, and derives the detection point by performing FFT analysis on the reflected wave. The information about the detection point includes the distance to the vehicle at each reflection point, the relative speed, the azimuth angle, the radio wave intensity, and whether or not the reflection point is a stationary point.

The control unit 51 detects the target by creating a list of the derived detection points. The control unit 51 periodically transmits the transmitted wave, receives the reflected wave, and creates a list of detection points. The control unit 51 periodically creates a list of detection points, and creates the list each time. Alternatively, the control unit 51 may add or update information to the already created list of detection points according to the processing cycle.

The control unit 51 creates a correction angle table in parallel with the processing of S01 (S100). The control unit 51 generates, for example, a child process of the processing process of S01, and processes S100 in this child process. Alternatively, the control unit 51 may perform multi-thread control in the processing process of S01 and perform the processing of S100. The control unit 51 creates a correction angle table for storing the correction angles for each of the azimuth angles as shown in FIG. 6 in association with each other, and stores the correction angles in the storage unit 52. Details of the processing of S100 will be described later.

The control unit 51 corrects the azimuth angle (S02). The control unit 51 refers to the correction angle table created in S001 at the azimuth angle of each detection point in the detection point list, reads out the correction angle corresponding to the azimuth angle, and corrects the azimuth angle according to the correction angle.

The control unit 51 outputs information about the target (S03). Based on this list of detection points, the control unit 51 adds the azimuth angle corrected by S02, and for example, notifies the target regarding collision avoidance with the target which is a stationary point or a moving point or a target which is a moving point. Information related to the body ECU 6 is output in order to perform tracking prediction.

FIG. 8 is a flowchart showing the processing of the control unit 51 according to the first embodiment (basic form).
The control unit 51 of the radar ECU 5 constantly executes the following processing in a state where the IG switch (ignition) of the vehicle 1 is on.

The control unit 51 acquires a list of detection points (S101). The control unit 51 creates a list of detection points according to a series of processing cycles based on the analysis result of the reflected wave in another process. For example, the control unit 51 communicates between processes to create a list of detection points, acquires a plurality of cycles of the created list, and outputs data related to each detection point included in the list, for example, in a volatile memory. It is stored in the storage unit 52.

The control unit 51 extracts a detection point that becomes a stationary point at the detection point (S102). Information about each detection point is registered in the list of detection points, and the information includes information on whether or not the detection point is a stationary point. The stationary point corresponds to a detection point by a reflection point of a stationary target such as equipment provided on both sides of a road such as a guardrail or a soundproof wall. The control unit 51 extracts the detection points that are stationary points from the acquired list of detection points.

The control unit 51 determines whether the vertical distance between the reference target and the own vehicle is already stored (S103). In the process described later, the control unit 51 derives the vertical distance between the reference target and the own vehicle, and stores the derived distance in the storage unit 52. Therefore, in the previous process, when the vertical distance between the reference target and the own vehicle is already derived and stored (S103: YES), the stored distance is used after S107. Perform processing. Even if the vertical distance between the reference target and the own vehicle has already been derived and stored, if there is a change in the running state or running environment of the own vehicle, the stored distance will be used. Assuming that the reliability is low, the processing after S104 may be executed as in the case where the distance is not stored. Changes in the traveling state of the own vehicle include, for example, the own vehicle changing lanes or turning. Regarding the fluctuation of the traveling environment of the own vehicle, for example, it may be considered that the traveling environment has changed due to the elapse of a period of a predetermined number of cycles or more.

When the distance between the reference target and the own vehicle in the vertical direction is not yet stored (S103: NO), the control unit 51 extracts a detection point located perpendicular to the traveling direction (S104). The control unit 51 acquires and stores a plurality of lists created by a plurality of cycles in the process of S101. In the list of detection points, information about the detection points acquired over a plurality of cycles is registered and stored in the storage unit 52. Based on the acquired list, the control unit 51 extracts a detection point whose azimuth angle is approximately 90 ° (perpendicular) with respect to the traveling direction of the own vehicle, and stores it in the storage unit 52. The control unit 51 extracts a detection point perpendicular to the traveling direction of the own vehicle, that is, the x component shown in FIG. 5 is 0. The number of the detection points extracted will increase according to the number of cycles. The control unit 51 may extract detection points that exist perpendicular to the traveling direction of the company based on the detection points due to the reflected waves received during the period in which the vehicle is traveling straight. In determining whether or not the own vehicle is traveling straight, the control unit 51 may make the determination based on whether the vehicle speed of the own vehicle is equal to or higher than a predetermined value or the rotational angular velocity (yaw rate) of the own vehicle.

The control unit 51 determines whether or not a predetermined number or more of detection points have been extracted (S105). The control unit 51 refers to the acquired list of detection points and determines whether or not the number of extracted detection points existing perpendicular to the traveling direction of the own vehicle is equal to or greater than a predetermined number. The predetermined number is appropriately determined based on the accuracy required for extracting the detection points and the like. When the number of extractions is not equal to or more than a predetermined number (S105: NO), the control unit 51 ends the process.

When the number of extractions is equal to or greater than a predetermined number (S105: YES), the control unit 51 extracts detection points of targets existing horizontally to the traveling direction of the own vehicle (S106). Among the detection points acquired over a plurality of cycles, a plurality of detection points that are perpendicular to the traveling direction of the own vehicle are extracted. The distance to the own vehicle at each of the extracted vertical detection points may differ due to multiple reflections or the influence of other vehicles running in parallel. Therefore, the control unit 51 confirms the number of detection points corresponding to each distance between each detection point and the own vehicle at the detection points extracted in S104 and located perpendicular to the own vehicle. For example, when 10 detection points are extracted and the distance between the 8 detection points is about 5 m and the distance between the 2 detection points is about 1.5 m, more detection points are extracted. It is extracted as a detection point by a target that exists horizontally to the direction of travel of the vehicle.

Even when a plurality of detection points perpendicular to the traveling direction of the own vehicle are extracted, for example, the reflection point having the highest reflection intensity may be recognized as a reflection point by a target such as a guardrail. The distance of the detection point by multiple reflection is a multiple of the distance of the original detection point, that is, the detection point of the target. Therefore, even when a plurality of detection points having different distances from the target are extracted, the detection points having a distance corresponding to a multiple of the distance of any of the detection points are excluded as due to multiple reflection. By doing so, it is possible to suppress false detection due to multiple reflections. Alternatively, the control unit 51 may recognize it as a reflection point by a target such as a guardrail based on a standard deviation at the distance of each of the extracted detection points or a statistical means such as a histogram. The distance to the own vehicle at each of the plurality of detection points extracted in this way is included within a predetermined deviation. Therefore, the control unit 51 determines by the processing of S105 and S106 whether or not there are a predetermined number or more of a plurality of detection points whose distance (vertical component) from the traveling direction of the own vehicle is within a predetermined deviation.

The control unit 51 derives the vertical distance between the reference target and the own vehicle (S107). The control unit 51 determines the average value of the distances between the detection points and the own vehicle at the detection points of the target objects parallel to the traveling direction of the own vehicle extracted in S106, that is, the reference target such as the guardrail. Derived. That is, the average value of the distances is the distance (vertical component) in the direction perpendicular to the traveling direction of the own vehicle between the own vehicle and the reference target. The reference target is not limited to the guardrail, but includes equipment such as noise barriers and walls that exist parallel to the traveling direction of the vehicle.

As described above, the detection points located perpendicular to the own vehicle are extracted over a plurality of cycles, and the distances from each of these detection points to the own vehicle cause some variation. Therefore, the control unit 51 can deal with the variation by deriving the average value of the distances of the detection points extracted in S106 from the own vehicle. The distance is not limited to the derivation based on the average value, and may be derived using the standard deviation.

The control unit 51 stores in the storage unit 52 the distance in the direction perpendicular to the traveling direction of the own vehicle between the derived own vehicle and the reference target. Next time, when a process for executing this process is generated, the control unit 51 refers to the distance stored in the storage unit 52 and determines the process of S103 described above. By reusing the distance in the direction perpendicular to the traveling direction of the own vehicle between the own vehicle derived in the previous processing and the reference target, the processing content can be reduced and the processing speed can be improved.

The control unit 51 extracts all the detection points by the target existing parallel to the traveling direction of the own vehicle (S108). In the list of detected detection points acquired by the control unit 51, the distance of the vertical component with respect to the traveling direction of the own vehicle is within a predetermined range with respect to the average value of the distances between the derived own vehicle and the detection points located vertically. The detection point is extracted as a detection point by a target existing parallel to the traveling direction of the own vehicle. The predetermined range may be increased according to the distance of the parallel component with respect to the traveling direction of the detection point and the own vehicle, for example. That is, as shown in FIG. 5, a predetermined angle range such as ± 1 ° is determined based on a target existing parallel to the traveling direction of the own vehicle such as a guardrail, and a detection point existing within the angle range is set as a guardrail or the like. These detection points may be extracted as the detection points according to the above. Alternatively, these detection points are extracted by assuming that the detection points within a predetermined range as ± 10% of the average value of the distances between the derived own vehicle and the detection points located vertically are the detection points by the guardrail or the like. It may be a thing.

The control unit 51 derives the correction angle (S109). The control unit 51 acquires the detection points extracted in S108, that is, the distances and azimuth angles of the detection points by the reference target such as the guardrail to the own vehicle. These distances and azimuths are stored in the storage unit 52 as information regarding the list of detection points acquired in the process of S101. The control unit 51 acquires these information by reading out the distance (l) and the azimuth angle by referring to the storage unit 52.

The control unit 51 has the distance (gr_y) derived in S107, that is, the distance (gr_y) in the direction perpendicular to the traveling direction of the own vehicle between the own vehicle and the reference target, and the own vehicle at the detection point extracted in S108. The assumed azimuth angle is derived based on the distance (l) from. This assumed azimuth angle is an azimuth angle between the ideal point located on a stationary object and detected as shown in FIG. 4 and the own vehicle. As for the assumed azimuth angle, as described above, the angle of a right triangle is calculated with the distance (l) between the detection point and the own vehicle as the hypotenuse and the vertical distance (gr_y) as the reference target as the opposite side (arcsin (arcsin). Derived by gr_y / l)). Alternatively, from the distance (l) between the detection point and the own vehicle and the vertical distance (gr_y) between the reference target and the reference target, the distance parallel to the direction of travel of the own vehicle (ideal_x) from the reference target. Is calculated (ideal_x = (l ^ 2 --gr_y ^ 2) ^ 1/2), and the assumed azimuth angle is calculated based on the horizontal distance (ideal_x) and the vertical distance (gr_y) (acrtan (gr_y /). ideal_x)) may be used. The control unit 51 derives a correction angle with respect to the azimuth angle at each detection point based on the difference between the assumed azimuth angle derived at each detection point and the azimuth angle of each detection point.

The control unit 51 stores the azimuth angle and the correction angle in the storage unit 52 (S110). The control unit 51 associates the derived correction angle with the corresponding azimuth angle and stores it in the storage unit 52. The corresponding azimuth angle is the azimuth angle of the detection point used in the difference processing for deriving the correction angle in the processing of S109. The storage unit 52 is provided with, for example, a correction angle table (see FIG. 6) for associating the azimuth angle and the correction angle corresponding to the azimuth angle, and the control unit 51 is prepared with the azimuth angle and the correction angle table. By registering the correction angles corresponding to the azimuth angles, these are stored in the storage unit 52.

The control unit 51 is based on the distance between a stationary object (target) existing parallel to the traveling direction of the own vehicle and a plurality of reflection points (detection points) by the stationary object (target). Derivation of the original azimuth angle (assumed azimuth angle) between the mark and the own vehicle. Therefore, it is possible to accurately derive the assumed azimuth angle without requiring the relative speed between the own vehicle and the target, and to derive the correction angle that is the difference between the assumed azimuth angle and the detected azimuth angle.

The control unit 51 is perpendicular to a stationary object existing parallel to the traveling direction of the own vehicle according to the average value of the distances to the own vehicle from the reflection points (detection points) of a plurality of targets detected within a predetermined cycle. Derivation of the directional distance (vertical component). Therefore, even if the distance to the own vehicle varies at the plurality of detection points, the distance to the stationary object can be accurately derived.

(Embodiment 2)
FIG. 9 is a flowchart showing the processing of the control unit 51 according to the second embodiment (update). The process of the control unit 51 of the second embodiment is different from the process of the first embodiment in that the correction angle stored in the storage unit 52 is updated. The control unit 51 performs the processes of S201 to S209 in the same manner as the processes of S101 to S109 of the first embodiment. In addition, in the notation of the flowchart, the description of the processing of S202 to S208 is omitted.

The control unit 51 determines whether or not the correction angle derived in S27 is stored in the storage unit 52, that is, whether or not the correction angle is unmemorized (S210).

When the correction angle is not stored (S210: YES), that is, when the correction angle is associated with the corresponding azimuth angle and is not yet stored in the storage unit 52, the control unit 51 is the process S110 of the first embodiment. The process of S211 is performed in the same manner as the process.

When the correction angle is not unmemorized (S210: NO), that is, when the correction angle is associated with the corresponding azimuth angle and is already stored in the storage unit 52, the control unit 51 and the correction angle derived in S209 , A difference from the already stored correction angle is derived, and it is determined whether or not the difference is within a predetermined value (S220). The term “within a predetermined value” includes, for example, that the correction angle derived in S209 is within 90% to 110% of the already stored correction angle.

If the difference is not within the predetermined value (S220: NO), the control unit 51 ends the process. That is, the correction angle derived in S210 is discarded. If the difference is not within the predetermined value, it is assumed that the reliability of the target detection result, that is, the information in the detection point list, such as the correction angle derived this time or the azimuth angle corresponding to this correction angle, is low. By discarding the correction angle having a low reliability as described above, the reliability of the correction angle already stored can be ensured. If the difference is not within a predetermined value, the fact that the data related to the detection point at the detected target (reflection point) includes an abnormal value (alert) may be output to the notification unit 8 via, for example, the body ECU 6.

When the difference is within a predetermined value (S220: YES), the control unit 51 calculates the average value of the correction angle derived in S209 and the already stored correction angle (S221). In calculating the average value, the control unit 51 may calculate the weighted average value by multiplying the correction angle derived in S209 and the already stored correction angle by different weighting coefficients. For example, the already stored correction angle weighting coefficient is set to 0.8, the correction angle weighting coefficient derived this time in S209 is set to 0.2, and the already stored correction angle weighting coefficient is set to 0.2. By making it larger than the weighting coefficient of the correction angle derived this time, it is possible to suppress an excessive or abrupt change in the correction angle. Alternatively, the control unit 51 stores a plurality of correction angles stored in the past as a history in the storage unit 52, and calculates a moving average based on the plurality of correction angles and the correction angles derived this time as an average value. May be good.

The control unit 51 updates the correction angles corresponding to the respective azimuth angles by overwriting the already stored correction angles with the average value of the correction angles calculated in S221 (S223).

When the correction angle corresponding to the azimuth angle is already stored in the control unit 51 and the correction angle corresponding to the azimuth angle is newly derived thereafter, the correction angle stored in the storage unit 52 Is updated by the newly derived correction angle. Therefore, even if the detection of the azimuth angle is deviated over time according to the traveling of the vehicle 1, the correction angle is updated as the vehicle 1 travels to ensure the freshness or reliability of the correction angle. be able to.

The control unit 51 updates the correction angle based on the already stored correction angle and the newly derived correction angle, such as the average value of the already stored correction angle and the newly derived correction angle. Therefore, it is possible to prevent the correction angle from being excessively or suddenly changed due to the update.

The embodiments disclosed this time should be considered as exemplary in all respects and not restrictive. The scope of the present invention is indicated by the scope of claims, not the meaning described above, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Vehicle (own vehicle)
10 Body frame 11 Front bumper 12 Rear bumper 13 Holding member 2 In-vehicle LAN
3 Target detection device 4 Radar device 41 Transmitter 42 Transmitter antenna 43 Receiver 44 Receiver antenna 5 Radar ECU
51 Control unit 52 Storage unit 53 Communication unit 54 Input / output interface 6 Body ECU
61 Control unit 62 Storage unit 63 Communication unit 64 Input / output interface 7 Vehicle speed detection unit 8 Notification unit (speaker, display)

Claims (9)

A target detection device mounted on a vehicle and detecting a target existing around the vehicle.
An azimuth angle deriving unit that derives the azimuth angle between the target and the own vehicle,
A distance deriving unit that derives a first distance between the target and the own vehicle, and a second distance between the target and the own vehicle that exists in a direction substantially perpendicular to the traveling direction of the own vehicle.
A correction angle deriving unit for deriving a correction angle for correcting the azimuth angle based on the first distance and the second distance is provided.
The first-distance target and the second-distance target are stationary objects that exist in parallel with the traveling direction of the own vehicle.
The transmitted wave transmitted from the radar device mounted on the own vehicle is reflected as a reflected wave from a stationary object and is reflected.
The target detection unit detects the reflection point based on the received reflected wave, and
The distance derivation unit
Wherein deriving a first distance between the reflection point and the vehicle,
A second distance between the reflection point of the stationary object located in the direction perpendicular to the traveling direction of the own vehicle and the own vehicle is derived.
The azimuth deriving unit
Derived the first azimuth angle between the own vehicle and the reflection point,
Based on the first distance and the second distance, the second azimuth angle between the own vehicle and the ideal point is derived.
The correction angle derivation unit
A target detection device characterized in that the difference between the first azimuth angle and the second azimuth angle is derived as a correction angle. The claim is characterized in that the correction angle deriving unit derives the correction angle based on the difference between the second azimuth angle derived from the first distance and the second azimuth and the first azimuth angle. The target detection device according to 1. Characterized in that it comprises a storage unit in which the azimuth angle deriving unit the corrected angle to derive relative s the first azimuth angle respectively derived, stored in association with the people correction angle husband out said first azimuth angle, respectively and conductor The target detection device according to claim 1 or 2. When the correction angle deriving unit derives a correction angle having the same azimuth as the first azimuth corresponding to the correction angle after the correction angle is stored in the storage unit, it is stored in the storage unit. The target detection device according to claim 3, further comprising an update unit for updating the correction angle. The update unit is stored in the storage unit based on the correction angle already stored in the storage unit and the correction angle derived by the correction angle derivation unit after the correction angle is stored in the storage unit. The target detection device according to claim 4, wherein the correction angle is updated. When the second distance is derived by a predetermined number or more within a predetermined period during the traveling of the own vehicle, the correction angle deriving unit is based on the first distance and the second distance derived by the predetermined number or more . The target detection device according to any one of claims 1 to 5, wherein a correction angle with respect to one azimuth angle is derived. The claim is characterized in that the correction angle deriving unit derives a correction angle with respect to the first azimuth angle based on the average value or standard deviation of the first distance and the second distance derived by a predetermined number or more. The target detection device according to 6. Derived the azimuth angle between the target detected as existing around the own vehicle and the own vehicle,
The first distance between the target and the own vehicle and the second distance between the target and the own vehicle existing in a direction substantially perpendicular to the traveling direction of the own vehicle are derived.
Based on the first distance and the second distance, a correction angle for correcting the azimuth angle is derived, and the correction angle is derived.
The first-distance target and the second-distance target are stationary objects that exist in parallel with the traveling direction of the own vehicle.
The transmitted wave transmitted from the radar device mounted on the own vehicle is reflected as a reflected wave from a stationary object and is reflected.
The reflection point is detected based on the received reflected wave, and the first distance and the first azimuth angle between the own vehicle and the reflection point are derived.
A second distance between the reflection point of the stationary object located in the direction perpendicular to the traveling direction of the own vehicle and the own vehicle is derived.
Based on the first distance and the second distance, the second azimuth angle between the own vehicle and the ideal point is derived.
A target detection method characterized in that the difference between the first azimuth angle and the second azimuth angle is derived as a correction angle. On the computer
Derived the azimuth angle between the target detected as existing around the own vehicle and the own vehicle,
The first distance between the target and the own vehicle and the second distance between the target and the own vehicle existing in a direction substantially perpendicular to the traveling direction of the own vehicle are derived.
Based on the first distance and the second distance, a correction angle for correcting the azimuth angle is derived, and the correction angle is derived.
The first-distance target and the second-distance target are stationary objects that exist in parallel with the traveling direction of the own vehicle.
The transmitted wave transmitted from the radar device mounted on the own vehicle is reflected as a reflected wave from a stationary object and is reflected.
The reflection point is detected based on the received reflected wave, and the first distance and the first azimuth angle between the own vehicle and the reflection point are derived.
A second distance between the reflection point of the stationary object located in the direction perpendicular to the traveling direction of the own vehicle and the own vehicle is derived.
Based on the first distance and the second distance, the second azimuth angle between the own vehicle and the ideal point is derived.
A program that executes a process of deriving the difference between the first azimuth angle and the second azimuth angle as a correction angle.

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