JP2009300210A - Monitoring device of surroundings of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a "monitoring device of surroundings of a vehicle" which is capable of distinguishing an object needless to detect, while detecting with excellent sensitivity an object being remote from the vehicle. <P>SOLUTION: A surrounding vehicle detecting device 10 includes a transmission wave generating part 20, an ultrasonic sensor 30 which transmits an ultrasonic wave, based on a transmission signal, and receives a reflected wave thereof, a reception detecting part 40 which detects a signal received by the ultrasonic sensor 30, a reflected wave detecting part 50 which detects a reception signal of the reflected wave, based on the result of the above detection, a reflected wave amplifying part 60 which amplifies the reception signal of the reflected wave, a warning part 70 which issues a warning or the like, using the signal amplified by the reflected wave amplifying part 60, and a detection level setting part 80 which sets a detection level of the reflected wave detecting part 50. The detection level setting part 80 sets the level as a function which has such a negative inclination that the detection level becomes lower as a distance from the vehicle to the object becomes larger. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle periphery monitoring apparatus that monitors the periphery of a vehicle, and more particularly, to a monitoring technique using transmission / reception waves such as millimeter wave radar and ultrasonic waves.

  By installing ultrasonic waves and radar transmission / reception devices in vehicle bumpers, etc., and receiving the reflected waves reflected by objects around the vehicle, the distance and speed from the vehicle to the object are detected, and sound of danger is heard. There is known a technique for warning by a display. In the detection of an object using such a transmitted / received wave, it is required to accurately extract a reflected wave from the object from noise or noise. For example, Patent Document 1 includes a reception ratio calculation unit that calculates a ratio in which a reception signal is included in a reception gate that is a time zone for receiving a reception signal, and the calculated reception ratio is less than a threshold value. A technique is disclosed in which it is determined that an obstacle detection operation can be normally performed and the obstacle detection operation is prohibited or a warning is displayed when a threshold value is exceeded.

JP-A-4-48206

  In the case of a transceiver using ultrasonic waves, the reception level or reception intensity of the reflected wave is inversely proportional to the square of the distance. That is, in order to detect an object far from the vehicle, the sensitivity must be improved so that even a signal with a low reception level can be detected.

  On the other hand, the intensity of the reflected wave of the object is not uniform depending on the object. Reflected waves from human bodies, vehicles, and obstacles have high intensity, but reflected waves from objects such as rain, snow, and dead leaves have low intensity. For this reason, if the sensitivity of the transmitter / receiver is improved, objects that should not be detected such as rain, snow, and dead leaves may be detected, which may give a false warning.

  FIG. 1 is a diagram illustrating an example of an object detection principle of a transceiver, where the vertical axis represents the reception level and the horizontal axis represents time. At time Ts, the transmission wave S is transmitted, and the reflected wave is received in a certain reception period TR from time Ts to time Te. The reception period TR is determined by the signal level of the transmission wave, the distance to be monitored from the vehicle, and the like. Here, an object to be detected such as a human body, a vehicle, and an obstacle is X, and an object that does not require detection of rain, snow, dead leaves, and the like is Y. However, the intensity of the reflected wave of the object X is greater than the intensity of the reflected wave of the object Y.

  The reflected wave RX1 of the object X at a short distance from the vehicle has a relatively large reception level that is smaller than the intensity of the transmission wave S, but the reception level of the reflected wave RX2 of the object X far from the vehicle is small. In addition, the reflected wave RY1 of the object Y at a short distance from the vehicle is smaller than the reflected wave RX1, the reflected wave RY2 of the object Y far from the vehicle is smaller than the reflected wave RY1, and more than the reflected wave RX2. Get smaller. Here, in order to detect the reflected wave RX2, it is necessary to set the detection level TH to be low, but in this case, the reflected wave RY1 at a short distance is detected.

  An object of the present invention is to provide a vehicle periphery monitoring device that can solve such a conventional problem and can distinguish an object that does not need to be detected while detecting an object far from the vehicle with high sensitivity.

  A vehicle periphery monitoring apparatus according to the present invention compares a reception means for transmitting a transmission wave, a reception means for receiving a reflected wave of the transmission wave, a received signal from the reception means and a detection level, and determines whether an object is present. The detection level is set as a function having a negative slope that decreases as the distance from the vehicle to the object increases. This detection level is inversely proportional to the distance from the vehicle to the obstacle, or inversely proportional to the reception time until the reflected wave is received.

  Preferably, the vehicle periphery monitoring device further includes detection level setting means for dividing the monitoring distance from the vehicle to the object into a plurality of parts and setting a detection level according to the divided monitoring distance. Preferably, the vehicle periphery monitoring device further includes a traveling direction calculation unit that calculates a traveling direction of the vehicle, and the detection level setting unit sets an inclination of the detection level based on the calculated traveling direction of the vehicle and the speed of the vehicle. .

  Preferably, when the angle difference between the traveling direction of the vehicle and the transmission direction of the transmission wave is θ, the vehicle speed is v, and the coefficient is R, the detection level setting means uses the inclination calculated by the following equation to determine the detection level. Set.

  According to the present invention, since the detection level for detecting an object is set as a function having a negative slope that decreases as the distance to the object increases, the object is detected at a long distance from the vehicle with high sensitivity. On the other hand, an object that does not require detection of rain, dead leaves, noise, or the like at a short distance can be distinguished from an object that requires detection.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings. In this embodiment, an example in which an object around a vehicle is detected using an ultrasonic sensor and monitored is shown.

  FIG. 2A is a block diagram illustrating a configuration of the vehicle periphery monitoring device according to the embodiment of the present invention. The vehicle periphery monitoring apparatus 10 according to the present embodiment includes a transmission wave generation unit 20 that generates a transmission signal for generating an ultrasonic wave, converts the transmission signal into an ultrasonic wave, and converts the received ultrasonic wave into an electrical signal. The ultrasonic sensor 30, the reception detection unit 40 for detecting the reflected wave signal received by the ultrasonic sensor 30, the reflected wave detection unit 50 for detecting the reception signal of the reflected wave based on the detection result, and the reception of the reflected wave A reflected wave amplification unit 60 that amplifies the signal, a warning unit 70 that issues a warning using the signal amplified by the reflected wave amplification unit 60, and a detection level setting unit 80 that sets a detection level of the reflected wave detection unit 50; including. Here, the detection level setting unit 80 is provided outside the reflected wave detection unit 50, but the reflected wave detection unit 50 may include the detection level setting unit 80 inside.

  FIG. 2B shows an example of attachment of the ultrasonic sensor. In the illustrated example, four ultrasonic sensors 30a to 30d are attached to the corners of the vehicle, that is, the left and right of the front bumper and the left and right bumpers of the vehicle. The position and number of ultrasonic sensors to be attached are not limited to this, and can be changed according to detection accuracy and monitoring accuracy.

  The transmission wave generation unit 20 generates a transmission signal necessary for transmitting an ultrasonic wave when the vehicle is operating, for example, when the vehicle is traveling or parked. In the case where ultrasonic waves are continuously output at regular intervals, the transmission wave generator 20 generates a pulse-shaped transmission signal at a constant cycle.

  The ultrasonic sensor 30 receives the transmission wave signal generated by the transmission wave generator 20, converts it into an ultrasonic wave, and outputs it. Further, when the transmitted ultrasonic wave irradiates an object located around the vehicle, the ultrasonic sensor 30 receives a reflected wave reflected by the object, converts it into an electrical signal, and outputs it.

  The reception detector 40 receives the reception signal output from the ultrasonic sensor 30, amplifies the received signal, and performs processing such as waveform shaping on the amplified reception signal. The reflected wave detection unit 50 compares the reception signal of the reflected wave from the reception detection unit 40 with the detection level (threshold value), and detects an object present around the vehicle when the reception signal exceeds the detection level. .

  The reflected wave amplification unit 60 amplifies the reception signal of the reflected wave that is to detect the object, and outputs this to the warning unit 70. The warning unit 70 displays a warning on a warning screen or issues a warning by voice using the input amplified signal. The contents of the warning screen and the voice guide are stored in advance in a memory, for example.

  Furthermore, the vehicle periphery monitoring apparatus of the present embodiment has a detection level setting unit 80. The detection level setting unit 80 adjusts the detection level in the reflected wave detection unit 50. In one preferable example, the detection level setting unit 80 decreases the detection level according to the distance to the object to be monitored during the reception period. In other words, the detection level is set to have a negative slope from the time when the transmission wave is transmitted until the time when the reception period ends. Since the reception intensity or reception level of the reflected wave is inversely proportional to the square of the distance, the reception level of an object located farther is smaller than that of a nearby object. By giving a negative slope to the detection level, it is possible to detect the reception signal of the reflected wave with an appropriate detection level corresponding to the distance from the object.

  FIG. 3 is a diagram for explaining the principle of detection of the received signal of the reflected wave according to this embodiment. 1 and the meaning thereof are the same, S is a transmitted wave, object X is an object that needs to be detected, object Y is an object that does not need to be detected, and RX1 and RX2 are reflected waves from the object X. , RY1, RY2 are reflected waves from the object Y.

As shown in FIG. 3, the detection level DL of the present embodiment is set to have a negative gradient in the reception period TR. Since the reception intensity of the reflected wave attenuates in inverse proportion to the distance from the vehicle to the object or the reception time, the detection level is increased on the short distance side and the detection level is decreased on the long distance side. The detection level DL can be defined by, for example, a linear function expressed by Equation (1). Here, T is a reception time from the transmission time Ts of the transmission wave S to reception of the reflected wave, and A is a slope and a negative constant. The intercept B is an initial value of the detection level DL and is a positive constant. The slope A and the intercept B can be determined, for example, by setting an obstacle that needs to be detected at least and calculating in advance the reception intensity corresponding to the distance to the obstacle. It is desirable to set a plurality of obstacles at different positions and determine the slope A and the intercept B so that all of them are detected as obstacles.

  As shown in FIG. 1, when the detection level TH is constant, the reflected wave RY1 from the object Y at a short distance that does not need to be detected cannot be eliminated. By giving the level DL a negative gradient, even if the reception intensity of the reflected wave RY1 of the object Y at a short distance is larger than the reception intensity of the reflected wave RX2 of the object X at a long distance, the reflected wave RY1 of the object Y is reduced. It can be excluded from detection.

  Next, a detection level setting method will be described. When the detection level having a negative gradient is always fixed, the detection level setting unit 80 is unnecessary, and the reflected wave detection unit 50 has a preset negative gradient detection level. On the other hand, when the detection level is changed, the detection level setting unit 80 sets the detection level of the reflected wave detection unit 50.

  FIG. 4A shows an example in which the inclination of the detection level is varied. The detection levels DL1, DL2, and DL3 have the same intercept B, but the inclinations A1, A2, and A3 are different, and the difference between the detection levels DL1, DL2, and DL3 increases as the distance to the object increases. Therefore, the detection sensitivity of an object at a long distance can be increased.

  FIG. 4B is an example in which the value of the intercept is varied. The detection levels DL1, DL2, and DL3 have the same slope A, but different intercepts B1, B2, and B3. Therefore, the reception sensitivity can be changed over the entire reception period.

  The detection level setting unit 80 can include a detection level selection table 90 as shown in FIG. The table 90 defines the relationship between the reception sensitivity and the detection levels DL1, DL2, and DL3, and the detection level setting unit 80 selects a detection level according to the given reception sensitivity.

  The reception sensitivity may be automatically selected according to the speed of the vehicle and the weather condition, or may be selected by an input from the user. For example, when the vehicle moves at a high speed, it is important to monitor an object at a long distance. Therefore, high sensitivity is selected so that the detection level DL1 in FIG. 4 (a) is set, and the vehicle is parked or stopped. In such a case, high sensitivity is selected so that the detection level DL1 of FIG. 4B is set.

  In the above example, the detection level changes linearly. However, as shown in FIG. 5, the detection level DL4 may change stepwise or stepwise.

  Next, a second embodiment of the present invention will be described. In the second embodiment, the detection level setting unit 80 sets a plurality of vehicle monitoring levels and sets a detection level corresponding to each monitoring level. For example, the monitoring level is classified into three areas: a warning area, a caution area, and a safety area. The relationship of the distance D from the vehicle to the object in each region is expressed as follows.

Warning area: 0 ≦ D <α (m)
Caution area: α ≦ D <β (m)
Safe area: β ≦ D
However, α <β.

  Assuming that the reception periods corresponding to the warning, caution, and safety areas are Ta, Tb, and Tc, respectively, the detection level DL5 has negative slopes that differ depending on the warning area, the caution area, and the safety area, as shown in FIG. Is set. Thereby, an object can be detected with different sensitivities within the range of each monitoring area. Note that the number of monitoring area settings is not limited to the above three, but may be a different number.

  Next, a third embodiment of the present invention will be described. FIG. 7 is a diagram showing the configuration of the vehicle periphery monitoring apparatus according to the third embodiment of the present invention. The same components as those in FIG. 2 are denoted by the same reference numerals, and redundant description is omitted. The vehicle periphery monitoring device 10A according to the third embodiment is an improvement over the second vehicle periphery monitoring device, and includes a vehicle traveling direction calculation unit 100 and an inclination calculation unit 110.

  The traveling direction calculation unit 100 receives steering angle information of the steering wheel and calculates the traveling direction of the vehicle. The inclination calculation unit 110 calculates the inclination of each monitoring level based on the traveling direction of the vehicle calculated by the traveling direction calculation unit 100 and vehicle speed information received from a vehicle speed sensor or the like. The detection level setting unit 80 sets the detection level for each ultrasonic sensor with reference to the inclination calculated by the inclination calculation unit 110.

  The inclination calculation unit 110 sets the angle difference between the traveling direction of the vehicle and the ultrasonic beam (optical axis) transmitted from the ultrasonic sensor as θ and the vehicle speed as v, and calculates the warning area inclination and the attention area inclination. It calculates according to Formula (2) and Formula (3).

  Here, P and Q are coefficients. For example, P / Q can be set according to the user's driving skill (advanced / intermediate / beginner) and the type of vehicle (sedan / minivan, etc.).

  The detection level setting unit 80 sets an inclination for each warning area and attention area using the inclinations calculated by Equations (2) and (3). Also, as described in the first embodiment, the reception sensitivity can be set simultaneously.

  Next, a specific operation example of the third embodiment will be described. FIG. 8 shows the positional relationship between the vehicle and the obstacles Za to Zd in the extension direction of the corner of the vehicle. It is assumed that the obstacle Zc is in the warning area (<α) of the vehicle, the traveling direction F of the vehicle is toward the obstacle Zc, and is virtually the same distance as the obstacle Zc and is an ultrasonic sensor. It is assumed that obstacles Za, Zb, and Zd exist in the directions of 30a, 30b, and 30d.

  When the vehicle travels in the traveling direction F, the ultrasonic sensor 30c approaches the obstacle Zc abruptly, and the obstacle sensor 30b diagonally away from the obstacle Zc rapidly moves away from the obstacle Zb, and the ultrasonic sensor 30a. , 30d gently move away from the obstacles Za, Zd. In such a situation, it is desirable that the sensitivity of the ultrasonic sensor 30c toward the obstacle Zc is higher than that of other ultrasonic sensors.

  FIG. 9 is an example of setting the detection level. FIGS. 9A to 9D show the detection levels DLa, DLb, DLc, and DLd of the ultrasonic sensors 30a to 30d. S indicates the transmission intensity, and Ra to Rd indicate the reception intensity of the reflected waves of the obstacles Za to Zd by the ultrasonic sensors 30a to 30d.

  The ultrasonic sensor 30c in which the traveling direction F shown in FIG. 9C is directed toward the obstacle Zc is compared with that of the ultrasonic sensor 30b in which the detection level DLc in the warning area is far from the obstacle Zb shown in FIG. It is getting smaller. Thereby, the ultrasonic sensor 30c detects the obstacle Zc in the warning area (DLc <Rc), but the ultrasonic sensor 30b does not detect the obstacle Zb in the warning area (DLb> Rb).

  Further, the detection level DLc of the ultrasonic sensor 30c toward the traveling direction F is set such that the inclination of the warning area (0 to α) <the inclination of the caution area (α to β) <the inclination of the safety area (to β), The detection level DLb of the ultrasonic sensor 30b in the direction opposite to the traveling direction F is set to the inclination of the warning area (0 to α)> the inclination of the caution area (α to β)> the inclination of the safety area (to β). The In the warning area and the attention area, the inclination of the detection level DLc of the ultrasonic sensor 30c is smaller than the inclination of the detection level DLb of the ultrasonic sensor 30b.

  If the angle difference θ between the traveling direction and the ultrasonic beam becomes larger than 90 degrees, Cos θ becomes negative, so the original inclination becomes smaller. On the other hand, if the angle difference θ becomes smaller than 90 degrees, Cos θ becomes positive. Therefore, it becomes larger than the original inclination. In the ultrasonic sensors shown in FIGS. 9A and 9D, the angle differences θ with respect to the obstacle Z are 90 degrees and 270 degrees, respectively, so Cos θ is zero and the inclination is the same as the original inclination. It is.

  In the third embodiment, the inclination of the detection level of each monitoring area is changed according to the degree of approach to the obstacle from the traveling direction and speed of the vehicle, and the object can be detected according to the collision risk. And in the case as shown in FIG. 9, the vehicle periphery monitoring apparatus can notify that there is an obstacle in the traveling direction F of the vehicle.

  The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the specific embodiment, and various modifications can be made within the scope of the present invention described in the claims. Deformation / change is possible.

It is a figure explaining the detection operation of the conventional vehicle periphery monitoring apparatus. FIG. 2A is a block diagram illustrating a configuration of a vehicle periphery monitoring device according to an embodiment of the present invention, and FIG. 2B is a diagram illustrating an installation example of an ultrasonic sensor. It is a figure explaining the detection operation of the vehicle periphery monitoring apparatus of a present Example. FIGS. 4A and 4B are diagrams illustrating a detection level setting method according to the present embodiment, in which FIG. 4A illustrates an example of a detection level having a different slope, FIG. 4B illustrates an example of a detection level having a different intercept value, and FIG. ) Is a diagram illustrating an example of a detection level selection table. It is a figure which shows the other example of a detection level. It is an example of the detection level which concerns on 2nd Example of this invention. It is a figure which shows the structure of the vehicle periphery monitoring apparatus which concerns on 3rd Example of this invention. It is a figure which shows the positional relationship of a vehicle advancing direction and an obstruction. FIG. 9A to FIG. 9D are detection levels for the ultrasonic sensors 30a to 30d.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Vehicle periphery monitoring apparatus 20: Transmission wave generation part 30: Ultrasonic sensor 40: Reception detection part 50: Reflection wave detection part 60: Reflection wave amplification part 70: Warning part 80: Detection level setting part 100: Travel direction calculation part 110: Inclination calculation unit S: Transmission wave Za, Zb, Zc, Zd: Obstacle

Claims (6)

A vehicle periphery monitoring device for monitoring a vehicle periphery,
A transmission means for transmitting a transmission wave;
Receiving means for receiving the reflected wave of the transmitted wave;
A detection means for comparing the reception intensity from the reception means and the detection level, and detecting the presence or absence of an object,
The vehicle periphery monitoring device, wherein the detection level is set as a function having a negative slope that decreases as the distance from the vehicle to an object increases. The vehicle periphery monitoring device according to claim 1, wherein the detection level is inversely related to a distance from the vehicle to an obstacle. The vehicle periphery monitoring device according to claim 1, wherein the detection level is inversely proportional to a reception time until receiving a reflected wave. The vehicle periphery monitoring device according to claim 1, further comprising a detection level setting unit configured to divide a monitoring distance from the vehicle to an object into a plurality of parts and to set a detection level according to the divided monitoring distance. . The vehicle periphery monitoring apparatus further includes a traveling direction calculation unit that calculates a traveling direction of the vehicle, and the detection level setting unit sets an inclination of the detection level based on the calculated traveling direction of the vehicle and the speed of the vehicle. Item 4. The vehicle periphery monitoring device according to Item 1. When the angle difference between the traveling direction of the vehicle and the transmission direction of the transmission wave is θ, the vehicle speed is v, and the coefficient is R, the detection level setting means sets the detection level using the slope calculated by the following equation: The vehicle periphery monitoring device according to claim 5.

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