JP2008064743A - Vehicular radar device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent detection of leakage of a vehicle in front of own vehicle from being left out, and recognition of an obstacle as a vehicle, in relation to a vehicular radar device mounted on a vehicle. <P>SOLUTION: The vehicular radar device 1 comprises a signal processing section 19 that divides the relative angle detection range of the object to own vehicle into three regions or more and sets an appropriate threshold in each region, in response to requirements, such as road information, such as, a road curves and distinction between general road and expressway, traveling speed of own vehicle, changes in road conditions due to weather conditions, and the specific running environment in which own vehicle is in. The radar device allows the driver in own vehicle to distinguish the vehicle traveling in front of own vehicle on the same lane from the obstacle, and prevents detection of the obstacle from being left out. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an on-vehicle radar device that is installed in a vehicle and detects an object ahead by radio waves, and in particular, sets a threshold value of reflected wave intensity from an object for each region and detects an object based on the set threshold value. The present invention relates to an in-vehicle radar device.

  An in-vehicle radar device that is installed in front of a vehicle and measures the distance to the object and the relative speed between the vehicle and the object has been proposed. By measuring the distance to the object and the relative speed, it is possible to operate an alarm device that warns in advance of a collision with the object, or to operate a brake to avoid a collision with the object.

  As a conventional on-vehicle radar device, for example, a radio wave beam in the millimeter wave region is transmitted, reflected waves reflected by an object are received by a plurality of receiving antennas, and the direction of the object is determined from the phase difference of the received waves. There is a phase monopulse type on-vehicle radar device.

  FIG. 1 is an explanatory view showing an example of reception of a reflected wave in a conventional phase monopulse type on-vehicle radar device. In FIG. 1, θ is an angle indicating the direction of the object, and the front direction of the vehicle is 0 °. The distance D is the interval between the two receiving antennas, and the phase difference φ is the phase difference between the two received waves. The two receiving antennas 14a and 14b receive the reflected wave reflected by the object in the direction of the angle θ. The angle θ indicating the direction of the object that reflects the reflected wave received by the two receiving antennas 14a and 14b is obtained by the following equation.

ここで、λは波長である。

Here, λ is a wavelength.

  In such an on-vehicle radar device, the threshold value of the reflected wave intensity for object detection is set to a constant value in any direction. When a reflected wave having an intensity exceeding the threshold is detected from a specific direction, it is determined that the object exists in the direction.

  On the other hand, according to the intensity distribution of the transmitted wave, a technique for giving separate threshold values to the central portion of the detection range of the reflected wave and the end portion of the detection range to facilitate the detection of the object, (For example, refer to Patent Documents 1, 2, 3, and 4).

In this technique, in the vicinity of 0 °, which is the central portion of the object detection range, the threshold value of reflected wave detection is increased, noise is blocked, and object detection is facilitated. Conversely, in the vicinity of the end of the detection range, the reflected wave detection threshold is lowered to facilitate the reception of the reflected wave. Such setting of the threshold corresponds to the characteristics of the antenna in which the intensity of the transmission wave is maximized at the center and decreases toward the end.
JP 2003-267084 A JP-T 9-506698 (USP 5633642) JP-A 64-65475 JP 2005-009913 A

  However, with such a detection method, it becomes difficult to detect the forward vehicle existing in the center of the detection range. In particular, in an active cruise control system (referred to as ACC) that detects a preceding vehicle traveling in the same lane with a radar or the like and automatically adjusts the speed according to the detected speed, there is a possibility that a detection failure of the preceding vehicle to be followed occurs. Sex occurs.

  That is, when the threshold value is set according to the intensity of the transmitted wave as in the prior art, the threshold value of the received wave intensity at the end of the detection range is reduced, and the threshold value of the received wave intensity at the center is increased. This means that the threshold of the central part where the vehicle ahead is likely to be detected is raised. Therefore, in the active cruise control system in which detection of the vehicle ahead is important, the detection failure of the vehicle ahead is not detected. Inviting, making it difficult for the vehicle ahead to follow.

  In a driving situation such as a curve, a vehicle traveling in front of the same lane may be confused with a vehicle traveling in front of a different lane, causing false detection.

  Furthermore, the radar device installed in the vehicle is not only used for the active cruise control system, but also a pre-crash safe system that detects and avoids obstacles such as guardrails, oncoming vehicles, and parallel running vehicles in advance ( PCS).

  Which system is more important depends on the situation of the vehicle, so the information to be supplied varies from system to system. However, it has not been proposed to set a threshold for supplying information corresponding to the change in the situation.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an on-vehicle radar device that can easily detect an object existing in the center of a detection range and prevents detection of a preceding vehicle to be followed.

  Another object of the present invention is to prevent a vehicle running in front of the same lane from being confused with a vehicle running in front of a different lane depending on the driving situation in which the vehicle is placed, thereby preventing erroneous detection. It is providing the vehicle-mounted radar apparatus for this.

  Furthermore, another object of the present invention is to provide an in-vehicle radar device for distinguishing and detecting a vehicle traveling in front of the same lane and an obstacle.

  In order to solve the above problems, a first aspect of the on-vehicle radar device according to the present invention includes a transmitter that transmits radio waves to an object, a receiver that receives the radio waves reflected by the object, and reception of the radio waves. The angle range in which the object is detected is divided into a plurality of areas of three or more, an intensity threshold for the received radio wave is set for each of the plurality of areas, and the intensity of the radio wave actually received in each area A processing unit that determines the presence of an object by comparing threshold values of the corresponding individual regions, and the processing unit automatically adjusts the speed according to the traveling speed of the vehicle. When the traveling speed supplied from the speed detecting device that detects the speed of the vehicle is equal to or higher than a predetermined speed, the threshold value of the second angle area of the detection range is set to the first angle area and the first angle area. Set lower than the threshold value of the angle region of 3

  A second aspect of the in-vehicle radar device according to the present invention is a transmitter that transmits radio waves to an object, a receiver that receives the radio waves reflected by the object, and an object detected by receiving the radio waves. Dividing the angle range into a plurality of regions of three or more, and for each of the plurality of regions, set an intensity threshold for the received radio waves, and in each region, the intensity of the radio waves actually received, A processing unit that determines the presence of an object by comparing the corresponding threshold values of the individual regions, and the processing unit detects the obstacle in advance and avoids the obstacle, Among the first angle region and the third angle region of the detection range in which the object is detected based on the road shape information supplied from the road shape recognition device that recognizes the shape of the road on which the vehicle travels, Threshold value for one of the areas Ri, is set to be higher.

  A third aspect of the in-vehicle radar device according to the present invention is a transmitter that transmits radio waves to an object, a receiver that receives the radio waves reflected by the object, and an object that is detected by receiving the radio waves. The angle range is divided into three or more areas, an intensity threshold for the received radio wave is set for each of the plurality of areas, and the intensity of the radio wave actually received in each area and the corresponding individual A processing unit that determines the presence of an object by comparing with a threshold value of the region, and the processing unit automatically adjusts the speed according to the traveling speed of the vehicle ahead. When the object existing in the area is moving, the threshold value of the area is lowered.

  According to a fourth aspect of the in-vehicle radar device of the present invention, a transmitting unit that transmits radio waves to an object, a receiving unit that receives the radio waves reflected by the object, and an object is detected by receiving the radio waves. Dividing the angle range into a plurality of regions of three or more, and for each of the plurality of regions, set an intensity threshold for the received radio waves, and in each region, the intensity of the radio waves actually received, A processing unit that determines the presence of an object by comparing the corresponding threshold values of the individual regions, and the processing unit detects the obstacle in advance and avoids the obstacle, When an object existing in the region is stationary, the threshold value of the region is lowered.

  Furthermore, in a preferred embodiment, when the traveling speed supplied from the speed detection device is equal to or higher than a predetermined speed, the processing unit sets the threshold value of the region in the center of the object detection range due to reception of the radio wave to be low. The object is recognized by setting the threshold value of the region at the end of the object detection range by receiving the radio wave high.

  Furthermore, in a preferred embodiment, the processing unit recognizes a road shape supplied from one or a plurality of road shape recognition devices that recognizes the shape of the road on which the vehicle on which the in-vehicle radar device is mounted as the running state. According to the information, the threshold corresponding to the road shape information is set in each object detection area.

  Furthermore, in a preferred embodiment, the road shape recognition device is an image pickup device that images the front of a vehicle on which the on-vehicle radar device is mounted and recognizes the road shape.

  Furthermore, in a preferred embodiment, the road shape recognition device is a car navigation device that recognizes a traveling position of a vehicle on which the in-vehicle radar device is mounted and displays the position on a map.

  Furthermore, in a preferred embodiment, the road shape recognition device is a yaw rate sensor that detects a change in the direction of a vehicle on which the on-vehicle radar device is mounted.

  Furthermore, in a preferred embodiment, one of the road shape recognition devices is a steering angle sensor that detects an angle of a steering wheel of a vehicle on which the in-vehicle radar device is mounted.

  Furthermore, in a preferred embodiment, one of the road shape recognition devices is a mobile phone connected to the vehicle control device via a USB (Universal Serial Bus) or a wireless device such as a terrestrial digital terminal device.

  Furthermore, in a preferred embodiment, the processing unit distinguishes between a highway and a general road supplied from a road type recognition device that recognizes a type of a road on which a vehicle on which the vehicle-mounted radar device is mounted is used as the running state. In accordance with the information, the threshold corresponding to the distinction information between the expressway and the general road is set in each area.

  Further, in a preferred embodiment, the traveling situation is a distinction between a road on which the vehicle is traveling on the left side or a right side, and the processing unit is a road on which a vehicle on which the in-vehicle radar device is mounted travels as the traveling state. The threshold corresponding to the setting is set in each area according to the setting of the road traffic classification setting unit that sets whether the traffic is left-hand traffic or right-hand traffic.

  Further, in a preferred embodiment, one of the road shape, road type, or traveling state recognition device is a service from an infrastructure type road state providing means such as DSRC (Dedicated Short Range Communication) or DSSS (Drivers Safety Support System). Is an in-vehicle device capable of receiving. More specifically, for example, information is provided from the DSRC at a junction of a highway or the like, and the threshold on the junction lane side is lowered. Or the weather information which raise | generates the risk of road environment, such as rain and fog, and the danger of a driver's recognition delay is received from digital terrestrial broadcasting etc., for example, The said threshold value is determined suitably according to this. This optimal combination information is preferably stored in advance in storage means such as a vehicle control device.

  In a preferred embodiment, the processing unit sets the threshold value when the relative speed of the object reflecting the received radio wave is a direction in which the vehicle and the object approach each other and is higher than a predetermined speed. The threshold value of the area where the exceeding radio wave is received is changed to be low.

  Furthermore, in a preferred embodiment, the processing unit lowers the threshold value when the speed of the front vehicle is lower than a predetermined value in a state in which the vehicle automatically adjusts the speed according to the traveling speed of the front vehicle. change.

  Furthermore, in a preferred embodiment, when the relative speed of the object reflecting the received radio wave is lower than a predetermined speed, the processing unit changes the threshold value of the area that receives the radio wave exceeding the threshold value to be low.

  Further, in a preferred embodiment, when the object that reflects the received radio wave is present in the region A and the relative speed is lower than a predetermined speed, the processing unit further differs from A in the radio wave exceeding the threshold value. When received from the region B, the threshold value of B is changed to be lower than the threshold value of A.

  The on-vehicle radar device of the present invention divides the relative angle detection range of an object with respect to the vehicle into three or more regions, road information such as curves and general / highway roads, the traveling speed of the vehicle, According to the specific driving environment where the vehicle is placed, such as a change in road surface condition due to the weather, by setting an appropriate threshold value in each area according to the above points, a vehicle traveling in front of the same lane, It is possible to perform detection while distinguishing it from an obstacle, and it is possible to prevent an obstacle from being detected.

  Furthermore, by lowering the threshold for an object that approaches rapidly from the relative speed of the detected object, an obstacle can be easily detected, and a pre-crash system can be handled. Further, by lowering the threshold value of an object having a small relative speed, it is possible to easily detect a vehicle traveling ahead at substantially the same speed, and to cope with cruise control.

  Hereinafter, according to the drawings, the embodiments of the present invention will be described as the first embodiment, the second embodiment, the third embodiment, the fourth embodiment, and the fifth embodiment of the on-vehicle radar device. It demonstrates in order of the form. However, the technical scope of the present invention is not limited to these embodiments, but extends to the matters described in the claims and equivalents thereof.

First Embodiment of In-vehicle Radar Device FIG. 2 is a configuration diagram of the in-vehicle radar device according to the first embodiment of the present invention, and FIG. 3 is a diagram showing a state of observation of a front vehicle by the in-vehicle radar device 1. 4 is a diagram illustrating a frequency relationship between a transmission wave and a reception wave when FMCW is applied as a signal format of the in-vehicle radar device.

  As shown in FIG. 3, the in-vehicle radar device 1 is installed in front of the vehicle 2, transmits a radio wave in the millimeter wave region over the detection range 3, and receives a reflected wave from the vehicle 4 ahead. Is detected. If there are obstacles in the vicinity, they are detected in the same manner.

  As shown in FIG. 2, the transmission system of the in-vehicle radar device 1 installed in the vehicle 2 includes a modulation signal generator 11, an RF oscillator 12 (VCO, etc.), and a transmission antenna 13. For example, the modulation signal generator 11 generates a modulation signal for frequency-modulating a millimeter wave carrier wave output from the RF oscillator 12. The oscillator 12 of the in-vehicle radar device 1 generates a transmission signal modulated by this modulation signal, and transmits it to the front of the vehicle 2 via the transmission antenna 13.

  A method for detecting the position and relative speed of an object from the frequencies of a transmission wave and a reception wave when FMCW is used as a signal format will be described with reference to FIG. In FIG. 4, the vertical axis represents frequency, and the horizontal axis represents time. The transmission frequency SF of the transmission wave transmitted based on the modulation signal generated by the modulation signal generator 11 of FIG. 2 rises at a constant rate over a certain period of time, then falls at the same rate, and returns to the original frequency.

  The transmission frequency SF repeats this periodic frequency change. The time change of the instantaneous frequency RF of the reception signal obtained by reflecting the transmission wave by the object is delayed by the time difference ΔT compared to that of the transmission frequency SF.

  Based on this time difference ΔT, the position to the object reflecting the transmission wave can be calculated. Further, the reception frequency RF receives the Doppler displacement DS based on the relative velocity of the object that reflects the transmission wave. Based on the Doppler displacement DS, the relative speed between the object and the vehicle 2 is obtained.

  Returning to FIG. 2, the transmitted transmission wave is reflected by an object existing ahead and received by a plurality of reception antennas 14 a, 14 b,. The receiving system of the in-vehicle radar device 1 includes receiving antennas 14a to 14z, amplifiers (AMP) 15a to 15z, mixers 16a to 16z, filters 17a to 17z, analog-digital converters (hereinafter referred to as A / D converters) 18a to 18z. And a signal processing unit 19.

  In this example, amplifiers 15a to 15z, mixers 16a to 16z, filters 17a to 17z, and A / D converters 18a to 18z are arranged in the same number as the receiving antennas 14a to 14z, respectively.

  A reception process with this configuration will be described. The reflected wave reflected by the object is received by the plurality of receiving antennas 14a to 14z. The plurality of receiving antennas 14a to 14z receive reflected waves from the respective objects, and the direction of the object causing the reflected waves is determined based on the phase difference of the received reflected waves.

  That is, the received signals from the receiving antennas 14a to 14z are amplified by the amplifiers 15a to 15z, respectively. The amplified signals are mixed with the transmission signal from the oscillator 12 by the mixers 16a to 16z, respectively. The mixers 16a to 16z generate and output a beat signal obtained by mixing the reception signal and the transmission signal.

  At this time, the distance and the relative speed are calculated using the beat signal in the section where the reception signal and the transmission signal both rise and the beat signal in the section where both the reception signal and the transmission signal fall. That is, this beat signal is input to the filters 17a to 17z, respectively. The signals whose bands are limited by the filters 17a to 17z are input to the A / D converters 18a to 18z and converted into digital signals, respectively. Each digital signal is input to the signal processing unit 19 and processed to obtain necessary information.

  The signal processing unit 19 calculates the distance and relative velocity of the object that reflects the transmission wave based on the input digital signal, as described later in FIG. 5 and the subsequent drawings, and further uses the angle measurement method to calculate the transmission wave. The direction of the reflecting object is calculated. The calculated direction, distance, and relative speed of the object are output from the signal processing unit 19 and supplied to an ECU (Electric Control Unit) 5 installed outside the in-vehicle radar device 1.

  Various information such as a vehicle speed signal P1, steering angle information P2, and a yaw rate signal P3 is supplied to the ECU 5 from each part of the vehicle 2. Based on these pieces of information and the determined direction, distance, and relative speed of the object, the ECU 5 warns the driver who is driving the vehicle via the alarm signal P5 and the display signal P6. Further, the ECU 5 can perform speed control to keep the accelerator constant by strengthening or weakening the accelerator via the throttle signal P4.

  Next, processing in the signal processing unit 19 will be described in detail with reference to FIGS. FIG. 5 is a process flowchart of the signal processing unit 19 according to the embodiment of the present invention. The signal processing unit 19 is supplied with digital signals from the A / D converters 18a to 18z. First, the signal processor 19 performs a Fourier transform on the supplied digital signal (step S1).

  In step S1, the signal processing unit 19 calculates the distance dn to the object reflecting the transmission wave and the relative velocity with the object from the obtained frequency information by Fourier transform (step S2). The distance dn to the object is calculated based on the time difference ΔT between the transmission wave and the reception wave as described with reference to FIG. Further, the relative velocity with respect to the object is calculated based on the frequency component of the Doppler displacement DS subjected to the reflected wave.

  There is a possibility of observing a plurality of objects by one observation, and here, the discrimination of objects having different distances will be described.

  FIG. 6 is a diagram illustrating observation of objects with different distances. The transmission wave transmitted over the detection range 3 shown in FIG. 3 is reflected by the objects B1 and B2. As shown in FIG. 6, the object B1 exists at a point with a distance L9, and the object B2 exists at a point with a distance L7.

  The signal processing unit 19 distinguishes the reflected wave from the object B1 and the reflected wave from the object B2 from the difference in the frequency of the reflected wave. In this way, the objects existing at different positions are discriminated. Next, observation of the orientation of an object at the same distance will be described.

  Returning to FIG. 5, for the reflected wave from the same distance dn as the obtained distance to the object, the direction of the object is estimated using the angle measurement method (step S3). For example, the angle measurement method is a radio wave arrival direction estimation method such as the Capon method or Music (Multiple Signal Classification).

  FIG. 7 shows an example of signal intensity distribution obtained by processing a reflected signal at a specific distance by an angle measurement method. In the following, a diagram represented by taking an angle on the horizontal axis represents a signal intensity distribution obtained by performing an angle measurement process on signals of the same distance.

  FIG. 7 is an angle distribution of the reflected wave intensity obtained by the signal processing unit 19. The horizontal axis is an angle in which the forward direction of the vehicle 2 is 0 radians, and the vertical axis is the intensity of the reflected wave detected at that angle. Here, it is determined that an object that reflects the transmission wave exists in a portion of the reflected wave intensity exceeding the threshold.

  FIG. 8 is an example of threshold setting for the case of FIG. 7 in the first embodiment of the present invention. As shown in FIG. 8, the detection area is divided into three, and a threshold value is set for each. In FIG. 8, the threshold value TH2 is set at the center of the vehicle 2 and applied to the detection of the reflected wave coming from the direction from the angle θ1 to θ2. The threshold value TH1 is set on the left side of the vehicle 2 and is applied to the detection of a reflected wave coming from the angle θ1 to the left (angle θ1 or less). Further, the threshold value TH3 is set on the right side of the vehicle 2 and is applied to detection of a reflected wave coming from the angle θ2 in the right direction (angle θ2 or more).

  Thus, the on-vehicle radar device according to the present embodiment divides the detection range into three or more regions, sets the central threshold value low, and sets the left and right threshold values high. Thereby, it is easy to detect an object existing in the center of the detection range, and it is possible to prevent detection omission of a preceding vehicle to be followed. At the same time, since the left and right thresholds are high, obstacles such as guardrails and oncoming vehicles are prevented from being erroneously detected as front vehicles to be followed.

  Such a threshold value setting is effective for following a preceding vehicle in an active cruise control system that automatically adjusts the inter-vehicle distance.

Second Embodiment of On-vehicle Radar Device As a second embodiment, an example in which a threshold value is set according to the speed of a vehicle on which the radar device of the present invention is mounted will be described. Here, there are three types of threshold setting modes. The on-vehicle radar device 1 in the present embodiment has the same configuration as the on-vehicle radar device 1 in the first embodiment. In the following description, it demonstrates using FIGS.

  8, FIG. 9 and FIG. 10 are examples of setting the threshold based on the traveling speed. Although FIG. 8 is used in the description of the first embodiment, as a result, the method of setting the threshold is the same, so that it is also used in the description of the second embodiment.

  In this example, a vehicle speed signal P1 is input to the in-vehicle radar device 1 of the present invention via the ECU 5. The signal processing unit 19 sets a threshold based on the vehicle speed signal P1.

  FIG. 8 is an example of threshold values set during high-speed traveling. This threshold value is set when the vehicle speed signal P1 informs that the speed is, for example, 80 km or more. The threshold value TH2 in FIG. 8 is set at the center of the vehicle 2 and is applied to the reflected wave coming from the direction from the angle θ1 to θ2. The threshold value TH1 is set on the left side of the vehicle 2 and is applied to the reflected wave coming from the left side from the angle θ1. Further, the threshold value TH3 is set on the right side of the vehicle 2 and is applied to the reflected wave coming from the right direction with respect to the angle θ2.

  In the threshold value setting in FIG. 8, the value of the central threshold value TH2 is made smaller than the values set in the two left and right threshold values TH1 and TH3. In the case of the distribution of the threshold value and the reflected wave intensity in FIG. 8, the on-vehicle radar device according to the present embodiment detects one object in the center of the detection range. Such a setting is performed when an active cruise control system that automatically adjusts the inter-vehicle distance accurately follows the preceding vehicle.

  In high-speed traveling, if the vehicle travels following the vehicle ahead, the possibility of contacting an obstacle is low. That is, in this setting, supply of information (object detection, position, etc.) to the active cruise control system is regarded as important both in the center of the detection range and on both the left and right sides.

  Next, FIG. 9 is an example of threshold values set during medium speed traveling. This threshold value is set when the vehicle speed signal P1 indicates that the vehicle is traveling at a speed of 30 km / h or more and less than 80 km / h, for example. In the threshold value setting in FIG. 9, the left threshold value TH1 is set larger than the set values of the two threshold values TH2 and TH3 on the center and right side of the detection range.

  In the case of the distribution of the threshold value and the reflected wave intensity in FIG. 9, the on-vehicle radar device in the present embodiment detects a total of three objects, one at the center of the detection range and two on the right side. Such a setting is used in the active cruise control system that automatically adjusts the inter-vehicle distance, when following an oncoming vehicle approaching while accurately following the preceding vehicle.

  On a left-handed road, if the vehicle follows the vehicle ahead, it is unlikely to come in contact with an obstacle on the left side, and only an oncoming vehicle needs to be warned. In other words, in this threshold setting, the supply of information to the active cruise control system is regarded as important both in the center and on the left side of the detection range, and the pre-crash safe system is regarded as important only on the right side. .

  FIG. 10 is an example of threshold values set while the vehicle is stopped or traveling at a low speed. This threshold value is set when the vehicle speed signal P1 indicates that the vehicle is traveling at a speed of less than 30 km / h, for example.

  In the threshold setting in FIG. 10, the same value is set for the three thresholds TH1, TH2, and TH3. The reason for this is to detect obstacles present on the left and right and the center of the detection range.

  A vehicle that is stopped or traveling at a very low speed is likely to be traveling on a narrow road, so that it is necessary to watch out for obstacles. Also, simply following the vehicle ahead is dangerous. That is, in this setting, supply of information to the pre-crash safe system is regarded as important both in the center of the detection range and on both the left and right sides, and the active cruise control system is not used.

  As described above, the in-vehicle radar device according to the present embodiment divides the detection range into three or more regions, sets the central threshold value low, and sets the edge threshold value high. Thereby, it is easy to detect an object existing in the center of the detection range, and it is possible to prevent detection omission of a preceding vehicle to be followed. Further, it is possible to select a detection target by setting a threshold value according to the traveling speed of the vehicle.

  In the present embodiment, the on-vehicle radar device 1 includes a traffic classification changeover switch (not shown), and can select left-hand traffic or right-hand traffic. Left-hand traffic is set in left-hand traffic countries such as Japan and the United Kingdom, and right-hand traffic is set in right-hand traffic countries such as the United States and France.

  In the description so far, the description has been made on the assumption that the left-hand traffic is set in the traffic classification selector switch of the in-vehicle radar device 1. When the right-hand traffic is set in the traffic classification selector switch, the threshold value of the reflected wave intensity on the left side and the threshold value on the right side in FIGS. 8, 9, and 10 of the present embodiment are interchanged.

  Furthermore, in the present embodiment, the angle distribution region of the reflected wave intensity is divided into three and a threshold is provided for each region. However, the division is not necessarily divided into three.

  FIG. 11 is a diagram illustrating threshold setting during high-speed traveling when the angle distribution region of the reflected wave intensity is divided into nine. When the angle distribution region of the reflected wave intensity is divided into three, the threshold value setting during high speed traveling is as described with reference to FIG. By further dividing this and setting the threshold values TH1 to TH9, it becomes possible to prevent the erroneous detection of the preceding vehicle to be followed and the omission of the detection of the obstacle more finely.

Third Embodiment of In-vehicle Radar Device FIG. 12 is a block diagram showing a connection example of the in-vehicle radar device according to the third embodiment of the present invention with another device. The on-vehicle radar device 1 in FIG. 12 has the same configuration as the on-vehicle radar device 1 in the first embodiment. For this reason, detailed description of the on-vehicle radar device 1 is omitted. A road shape recognition device 6 is connected to the in-vehicle radar device 1 in the present embodiment.

  The road shape recognition device 6 is composed of a camera 61 and an image processing device 62. In this case, the camera 61 captures an image in front of the vehicle 2 and supplies the image to the image processing device 62. This image is used for recognizing a white line on the road.

  That is, the image processing device 62 receives the image signal from the camera 61, recognizes the white line on the road, and supplies the position of the white line to the signal processing unit 19 of the in-vehicle radar device 1. The signal processing unit 19 recognizes that the road is curved to the right when the position of the supplied white line moves to the right, and recognizes that the road is curved to the left when it moves to the left.

  FIG. 13 is an explanatory diagram of road shape recognition in the present embodiment. The on-vehicle radar device 2 mounted on the vehicle 2 recognizes two white lines 7 within the visual field range 8 of the camera 61. When the white line 7 curves to the right, it recognizes that the running road curves to the right, and recognizes that the running road curves to the left if it curves to the left.

  FIG. 14 is an example of threshold values set in the in-vehicle radar device when the right curve is detected. In the threshold value setting of FIG. 14, the left threshold value TH1 is set larger than the two threshold values TH2 and TH3 at the center and right side of the detection range.

  This is because, on the right curve, obstacles such as guardrails are present on the left side, so that these obstacles whose reflected wave intensity is large are prevented from being mistaken as a preceding vehicle to be followed. The reason for setting the right threshold value low is that there is a possibility that the preceding vehicle to be followed may move to the right region in order to be wary of contact of an approaching oncoming vehicle.

  Therefore, in the setting of this threshold value, the supply of information to the active cruise control system is emphasized at the center and the left side of the detection range, and on the right side, the systems of both the active cruise control system and the pre-crash control system are emphasized. It becomes the setting for.

  FIG. 15 is an explanatory diagram of an example of threshold values set when a left curve is detected. In setting the threshold value in FIG. 15, the value of the right threshold value TH3 is made larger than the set values of the two threshold values TH1 and TH2 at the center and the left side of the detection range.

  The reason for this is that on the left curve, there are oncoming and parallel vehicles on the right side, so that the obstacle that increases the reflected wave intensity of the obstacle and the vehicle ahead should be misidentified. Is to prevent. The reason for setting the left threshold value low is that there is a possibility that the preceding vehicle to be followed may move to the left region in order to be wary of contact with obstacles beside the road.

  Therefore, in this setting, the supply of information to the active cruise control system is emphasized both in the center and on the right side of the detection range. On the left side, the active cruise control system and the pre-crash control system are connected. It is a setting for both systems.

  In this way, the on-vehicle radar device according to the present embodiment divides the detection range into three or more regions, sets the central threshold value low, and sets the edge threshold value high, thereby setting the center of the detection range. It is easy to detect an object existing in the section, and it is possible to prevent detection omission of a preceding vehicle to be followed.

  Further, by setting a threshold value according to the curve of the road that is running, it is possible to prevent erroneous detection of the preceding vehicle due to confusion with the guardrail, the oncoming vehicle, and the parallel running vehicle.

  In the present embodiment, the road shape recognition device 6 connected to the in-vehicle radar device 1 has been described as an example composed of the camera 61 and the image processing device 62. However, the road shape recognition device 6 may be a car navigation device that recognizes a position where the vehicle is traveling by position recognition by GPS (Global Positioning System) and displays the position on a map.

  The road shape recognition device 6 may be a steering angle sensor that detects the angle of the steering wheel. By detecting the angle of the steering wheel, it is possible to indirectly recognize the road shape during traveling. The road shape recognition device 6 may be a yaw rate sensor that detects a change in the direction of the vehicle. By detecting a change in the direction of the vehicle, the shape of the running road can be indirectly recognized.

  Further, the road shape recognition device 6 may be a magnetic nail sensor that detects magnetism from a magnet embedded on the road. By detecting the magnetism from the magnets embedded in the road, the shape of the running road can be directly recognized. Further, a plurality of these road shape recognition devices can be combined to increase the accuracy of detection information related to the road shape.

  The road shape recognition device 6 may be a mobile phone connected to the vehicle control device by means such as USB, or a wireless device such as a terrestrial digital broadcasting terminal. Map information received via a mobile phone or local terrestrial digital broadcast information may be acquired to support road shape recognition.

  Furthermore, the road shape recognition device 6 may be an in-vehicle device that can receive a service from infrastructure-type road condition providing means such as DSRC and DSSS.

Fourth Embodiment of In-vehicle Radar Device FIG. 16 is a configuration diagram of a connection example of the in-vehicle radar device according to the fourth embodiment of the present invention. The in-vehicle radar device 1 in FIG. 16 has the same configuration as the in-vehicle radar device 1 in the first embodiment. The on-vehicle radar device 1 in this embodiment is connected to a road type recognition device 9 that recognizes whether it is an expressway or a general road. Specifically, the road type recognition device 9 includes a car navigation device 91.

  The car navigation device 91 recognizes the current position of the vehicle 2 by GPS and compares it with the stored map information to determine whether the running road is an expressway or a general road, The in-vehicle radar device 1 is notified.

  FIG. 17 is an explanatory diagram of an example of threshold values set while traveling on a highway. In the setting of the threshold value in FIG. 17, the value of the right threshold value TH3 is made larger than the values set in the two threshold values TH1 and TH2 at the center and the left side of the detection range.

  The reason why the threshold value on the left side is lowered is that, on an expressway, there are fewer obstacles such as signboards appearing on the left side of the road (when passing on the left side) than ordinary roads, and they do not become obstacles for recognition of the preceding vehicle. The threshold value on the right side is increased because the highway is separated from the oncoming lane in the central separation zone, so that it is not necessary to be alert to the oncoming vehicle or there is less need to be alert.

  Therefore, in this setting, the supply of information to the active cruise control system is emphasized for the center and the right side of the detection range, and the supply of information to the pre-crash safe system is emphasized on the left side.

  In addition, the threshold value when driving on a general road is set according to the speed and the road shape according to the embodiments described so far.

  In this way, the on-vehicle radar device according to the present embodiment divides the detection range into three or more regions, sets the threshold value at the center of the detection range low, and sets the threshold value on the right side high. It is easy to detect an object existing in the center of the vehicle, and it is possible to prevent detection omission of a preceding vehicle to be followed. In addition, it is possible to prevent erroneous detection of the preceding vehicle by setting a threshold value according to whether the road being traveled is a general road or an expressway.

Fifth embodiment of the on-vehicle radar device In the first to fourth embodiments shown so far, the vehicle speed, the shape of the road, the distinction between the highway and the general road, etc. An example of setting a threshold has been described. However, in the fifth embodiment, the setting of the threshold is changed based on the detection result.

  FIG. 18 is an explanatory diagram of a threshold value setting example according to the fifth embodiment of the present invention, and FIG. 19 is an angular distribution of radio wave intensity transmitted by the transmission antenna. As shown in FIG. 19, it can be seen that the radio wave transmitted from the transmission antenna 13 has a large intensity at the center of the detection range and a small intensity at both the left and right ends. The on-vehicle radar device 1 in the present embodiment has the same configuration as the on-vehicle radar device 1 in the first embodiment.

  Such an angular distribution of the transmitted wave intensity is usually obtained by experiments or the like, but a threshold value as shown in FIG. 18 is set according to this. This is set, for example, in the case of performing only warning for an obstacle without using an active cruise control system. That is, this corresponds to the threshold setting during low-speed traveling in the second embodiment.

  In FIG. 18, threshold values from TH1 to TH9 are set according to the intensity distribution of the transmission wave in FIG. By setting the threshold value in this way, obstacles existing at various angles can be detected with high accuracy.

  In the present embodiment, as will be described with reference to FIG. 20, a new threshold value is set in a region where an object is actually detected. Further, a new threshold value is set in the area where the object is detected based on the speed of the detected object. As the detected speed of the object, the relative speed obtained in step S2 of the flowchart of FIG. 5 is used.

  That is, in an active cruise control system that detects a vehicle traveling ahead and automatically adjusts the distance between vehicles, if it can be determined from the speed of the object that it is a traveling vehicle, the object is observed at the angle observed. Lower the detection threshold of reflected wave intensity. For example, when an object that is determined to be a running vehicle is observed between one second ago and the present time, the set threshold value is reduced by 10%.

  Similarly, in the active cruise control system, when it is determined that the object is a stationary object from the speed of the object, the threshold value of the reflected wave intensity at the angle at which the object is observed is increased. For example, when an object that is determined to be a stationary object is observed between one second ago and the present time, the set threshold value is increased by 10%.

  FIG. 20 is an explanatory diagram of an example in which the threshold value is changed according to the observed speed of the object in the active cruise control system. When the reflected wave intensity as shown in FIG. 11 is observed, the threshold values TH1 to TH9 are changed in the respective ranges according to the observed speed of the object.

  Here, as a specific example of operation, consider a case in which a speed of 30 km / h is adopted as a detection object discriminating criterion, and if it is less than 30 km / h, it is determined as a stationary object, and if it is 30 km / h or more, it is determined as a forward vehicle.

  In FIG. 11, it is assumed that a vehicle traveling ahead is detected in an angle range in which threshold values TH4 to TH6 are set. In addition, it is assumed that a stationary object is detected in the other range.

  In this case, as shown in FIG. 20, the threshold values TH4 to TH6 set in the area where the traveling vehicle is detected are lowered by 10%, and the threshold values TH1 to TH3 set in the area where the stationary object is detected, and TH7 to TH8 are increased by 10%. Note that the threshold TH9 at which no object is observed does not change.

  By changing these threshold values, the peak TAA corresponding to the vehicle ahead is widened, so that the object can be easily observed. Also, peaks TAB, TAC, TAD and TAE corresponding to stationary objects are sometimes not observed as a result of the reduced width.

  The method of changing the threshold value in this way can be applied to other than the active cruise control system.

  For example, in a pre-crash safe system that detects an obstacle and brakes before a collision, the object is observed if it is determined from the speed of the object that the vehicle is traveling ahead Raises the threshold of reflected wave intensity at an angle. For example, when an object that is determined to be a running vehicle is observed between one second ago and the present time, the set threshold value is increased by 10%.

  Similarly, in the pre-crash safe system, when it is determined that the object is a stationary object from the speed of the object, the threshold value of the reflected wave intensity at the angle at which the object is observed is lowered. For example, when an object that is determined to be a stationary object is observed from one second before to the present, the set threshold value is lowered by 10%.

  FIG. 21 is an explanatory diagram of an example in which the threshold value is changed in accordance with the detected speed of the object in the pre-crash safe system. When the reflected wave intensity as shown in FIG. 11 is observed, the thresholds TH1 to TH9 change according to the observed speed of the object.

  Here, as a specific example of operation, consider a case in which a speed of 30 km / h is adopted as a detection object discriminating criterion, and if it is less than 30 km / h, it is determined as a stationary object, and if it is 30 km / h or more, it is determined as a forward vehicle.

  Here, in FIG. 11, it is assumed that a vehicle traveling ahead is detected in an angle range in which threshold values TH4 to TH6 are set. In addition, it is assumed that a stationary object is detected in other ranges.

  In this case, as shown in FIG. 21, the threshold values TH4 to TH6 are increased by 10%, and the threshold values TH1 to TH3 and TH7 to TH8 are decreased by 10%. The threshold value TH9 corresponding to the area where no object is detected does not change.

  As a result of these threshold changes, the peak TAA corresponding to the vehicle ahead is halved in the area used for detection, and as a result, sometimes no object is observed. In addition, the peaks TAB, TAC, TAD, and TAE corresponding to the stationary object are easily detected as a result of the width of the region used for detection being expanded.

  In this way, the on-vehicle radar device according to the present embodiment divides the object detection range into a plurality of areas, sets the threshold values of the reflected wave intensity in each area, and uses the threshold values to detect the detected object. The threshold value is changed according to the speed.

  Then, if you want to focus on the pre-crash safe system by determining whether the object is a stationary object or a moving vehicle, lower the threshold of the area where the stationary object is observed and focus on the active cruise control system In this case, the threshold value of the area where the traveling vehicle is observed is lowered. By doing so, it is possible to prevent erroneous detection of a preceding vehicle to be followed and obstacle detection failure.

  In the present specification, description has been made using an in-vehicle radar device having a phased array antenna. However, the antenna used in the present invention may be a monopulse antenna or a digital beam forming antenna. The antenna is not limited to a specific shape or arrangement.

  The on-vehicle radar device divides the range of detection of the relative angle of the object with respect to the vehicle into three or more regions, road information such as curves, general / highway classification, traveling speed of the vehicle, and road surface due to weather. Depending on the specific driving environment where the vehicle is placed, such as changes in the situation, by setting appropriate thresholds in each area, the vehicle traveling in front of the same lane and obstacles are detected separately It is possible to prevent the occurrence of obstacle detection failure. Furthermore, by lowering the threshold for an object that approaches rapidly from the relative speed of the detected object, an obstacle can be easily detected, and a pre-crash system can be handled. Further, by lowering the threshold value of an object having a small relative speed, it is possible to easily detect a vehicle traveling ahead at substantially the same speed, and to cope with cruise control.

It is an example of the reception of the reflected wave in the conventional vehicle radar apparatus of a phase monopulse system. It is a block diagram of the vehicle-mounted radar apparatus in embodiment of this invention. It is a figure which shows the mode of observation of the front vehicle in the vehicle-mounted radar apparatus of FIG. It is a figure which shows the relationship between the frequency of the transmission wave and reception wave of FIG. It is a process flowchart of the signal processing part of FIG. It is a figure which shows the observation condition of the object from which distance differs in FIG. It is explanatory drawing of angle distribution of the reflected wave intensity obtained by the signal processing part of FIG. It is explanatory drawing of the threshold value set during the high speed driving | running | working of the 1st Embodiment of this invention. It is explanatory drawing of the threshold value set during the medium-speed driving | running | working of the 2nd Embodiment of this invention. It is explanatory drawing of the threshold value set during the stop or low speed driving | running | working of the 2nd Embodiment of this invention. It is a figure which shows the threshold value setting in high speed driving | running | working at the time of dividing the area | region of the angle distribution of the reflected wave intensity of the 2nd Embodiment of this invention into 9 parts. It is a connection block diagram with the other apparatus of the vehicle-mounted radar apparatus in the 3rd Embodiment of this invention. It is a figure which shows the recognition of the road shape in embodiment of FIG. It is explanatory drawing of the threshold value set when the right curve in the embodiment of FIG. 12 is detected. It is explanatory drawing of the threshold value set when the left curve in the embodiment of FIG. 12 is detected. It is a connection block diagram of the vehicle-mounted radar apparatus in the 4th Embodiment of this invention. It is explanatory drawing of the threshold value set during driving | running | working on the highway in embodiment of FIG. It is explanatory drawing of the example of a setting of the threshold value in the 5th Embodiment of this invention. FIG. 19 is an angle distribution diagram of radio wave intensity transmitted by the transmission antenna in the embodiment of FIG. 18. FIG. 19 is an explanatory diagram of an example in which a threshold value is changed according to the observed speed of an object in the active cruise control system in the embodiment of FIG. 18. It is explanatory drawing of the example which changes a threshold value according to the speed of the observed object in the pre-crash safe system in embodiment of FIG.

Explanation of symbols

1 On-vehicle radar device 2 Vehicle 3 Detection range 5 ECU
6 Road Shape Recognition Device 11 Modulation Signal Generator 12 RF Oscillator 13 Transmitting Antenna 14 Receiving Antenna 15 Amplifier 16 Mixer 17 Filter 18 A / D Converter 19 Signal Processing Unit

Claims (4)

An on-vehicle radar device mounted on a vehicle,
A transmitter that transmits radio waves to an object;
A receiver that receives the radio wave reflected by the object;
The angle range in which an object is detected by reception of the radio wave is divided into a plurality of three or more areas, an intensity threshold for the received radio wave is set for each of the plurality of areas, and the actual reception is performed in each area. A processing unit that compares the intensity of the radio wave with a threshold value of the corresponding individual area to determine the presence of an object;
In the state where the processing unit automatically adjusts the speed according to the traveling speed of the vehicle and the traveling speed supplied from the speed detecting device that detects the speed of the vehicle is equal to or higher than a predetermined speed, The in-vehicle radar device, wherein the threshold value of the second angle region of the detection range is set lower than the threshold values of the first angle region and the third angle region. An on-vehicle radar device mounted on a vehicle,
A transmitter that transmits radio waves to an object;
A receiver that receives the radio wave reflected by the object;
The angle range in which the object is detected by receiving the radio wave is divided into a plurality of three or more areas, and an intensity threshold for the received radio wave is set for each of the plurality of areas, A processing unit that determines the presence of an object by comparing the intensity of the received radio wave with a threshold value of the corresponding individual region,
The processing unit detects the object based on road shape information supplied from a road shape recognition device that recognizes the shape of the road on which the vehicle travels in a state in which the vehicle detects and avoids an obstacle in advance. A vehicle-mounted radar device characterized by setting a threshold value of one of the first angle region and the third angle region of the detection range in which the detection of the vehicle is higher than the threshold value of the other region . An on-vehicle radar device mounted on a vehicle,
A transmitter that transmits radio waves to an object;
A receiver that receives the radio wave reflected by the object;
The angle range in which an object is detected by reception of the radio wave is divided into a plurality of three or more areas, an intensity threshold for the received radio wave is set for each of the plurality of areas, and the actual reception is performed in each area. A processing unit that compares the intensity of the radio wave with a threshold value of the corresponding individual area to determine the presence of an object;
The processing unit is configured to set the threshold value of the region when the vehicle is moving in a state in which the vehicle automatically adjusts the speed according to the traveling speed of the preceding vehicle. An on-vehicle radar device characterized by being lowered. An on-vehicle radar device mounted on a vehicle,
A transmitter that transmits radio waves to an object;
A receiver that receives the radio wave reflected by the object;
The angle range in which the object is detected by receiving the radio wave is divided into a plurality of three or more areas, and an intensity threshold for the received radio wave is set for each of the plurality of areas, A processing unit that determines the presence of an object by comparing the intensity of the received radio wave with a threshold value of the corresponding individual region,
The processing unit lowers the threshold value of the region when the vehicle detects an obstacle in advance and avoids the obstacle and an object existing in the region is stationary. Radar device.

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