JP2006343309A - Obstacle detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an obstacle detector capable of detecting accurately a position, a shape, and a space of an obstacle in the periphery of a vehicle, over a wide range. <P>SOLUTION: A transmission wave is transmitted from each of elements array-like arranged, and a reflected wave thereof in the obstacle is received by the each element. A distance up to the obstacle is calculated based on reception times of received signals thereof, and a direction of the obstacle is calculated based on phase differences of the reception signals in the respective elements. The phase difference of the transmission signal input into the each element is changed properly to control a multiplex directivity of the transmission wave, and a coefficient multiplied to the reception signal of the each element is changed properly to control the a multiplex directivity of the reception wave, for the purpose of detecting the obstacle over the wide range. In particular, the directivity is switched alternately between a narrow angle and a wide angle, by setting a phase difference alternately into the same phase or a reverse phase between the adjacent elements, to detect the position of the obstacle over the wide range. The position, the shape and the space of the obstacle in the periphery of a vehicle travel route are confirmed, based on positional information detected while moved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus for detecting an obstacle around a vehicle used for recognizing a parking area in order to assist parking, for example.

  In general, for example, a driving operation when a vehicle is parked in a predetermined parking area is one of driving operations with a high degree of difficulty among various driving operations. For this reason, various devices for supporting a parking operation have been proposed.

  For example, the apparatus described in Patent Literature 1 recognizes a parking area using a distance sensor that measures the distance of an obstacle. And the movement locus | trajectory of a vehicle at the time of parking in the recognized parking possible area is calculated and displayed.

  However, for example, when a distance sensor such as an ultrasonic sensor is used, the directivity becomes wide. Therefore, the obstacle is detected before the obstacle reaches the side of the distance sensor, and after passing through the obstacle. Even the obstacles will be detected. Therefore, the recognized parking area has an error from the actual parking area.

  In order to solve this problem, the apparatus described in Patent Literature 2 measures in advance the relationship between the distance detected by the distance sensor and the error in the traveling direction at the detected distance, and stores it as a correction width table. . And in the measurement of the parking width in the parking area detection, the correction width according to the detected distance is used as the correction value.

Moreover, in the obstacle detection device of Patent Literature 3, position information of the detected obstacle is stored, and the position information is updated to relative position information with the current vehicle. This can reduce the blind spot without increasing the number of obstacle detection sensors.
JP 61-48098 A JP 2003-31414 A JP 2003-114276 A

  As described above, in order to detect a parking area using the device described in Patent Document 2, the relationship between the distance detected by the distance sensor and the error in the traveling direction at the detected distance is accurately measured. There is a need.

  However, since the reflectance of the obstacle is different due to the shape and material of the obstacle, actually, the detectable range of the obstacle will be different if the shape and material of the obstacle are different. That is, when the shape and material of the obstacle are different, the relationship between the detection distance by the distance sensor and the error in the traveling direction at the detection distance is also different. Therefore, with the apparatus described in Patent Document 2, it is difficult to detect an accurate position for any obstacle.

  Similarly, since the distance sensor is used in Patent Document 3, the exact position of the obstacle cannot be detected. In particular, it is difficult to apply in the case where accurate obstacle detection is required, such as when a space where parking is possible is detected or when a vehicle passes through a narrow space.

  The present invention has been made in view of the above problems, and can detect the position and shape of an obstacle regardless of the type of obstacle, and can accurately detect a parking space and a movable space. An object is to provide a detection device.

  In order to achieve the above object, an obstacle detection apparatus according to claim 1 is installed in a vehicle and inputs a transmission signal to a plurality of elements arranged in an array and each element arranged in the array. A transmission means for transmitting a transmission wave having a predetermined directivity toward the periphery of the vehicle; and a reflected wave reflected by an obstacle existing around the vehicle by each element arranged in the array. Receiving means for determining the presence or absence of a wave, and when the receiving means determines that the reflected wave of the transmitted wave transmitted by the transmitting means has been received, the time when the reflected wave is received and the transmitting means transmits the transmitted wave A position detecting unit that calculates a distance of the obstacle based on a difference from the measured time and calculates a direction of the obstacle based on a phase difference of reflected waves received by the respective elements. To do.

  Thereby, not only the distance of the obstacle but also the direction can be detected. That is, the position of the obstacle can be accurately detected. Further, since it is not necessary to use a correction value as in Patent Document 2, an accurate position can be detected for any obstacle.

  Further, the direction of the obstacle may be calculated based on the time difference of the reflected wave received by each element as in the second aspect.

  The obstacle detection apparatus according to claim 3, wherein the transmission unit controls the directivity of the transmission wave by changing a phase of a transmission signal input to each element arranged in the array. .

  The combined directivity E (θ, φ) of transmission waves transmitted from each element arranged in an array is expressed by the following equation (hereinafter, a one-dimensional case is shown).

(Equation 1)
E (θ, φ) = E ₀ (θ, φ) × Σexp [j {(2π / λ) × (m × dx × sin θ × cos φ) + θ _m }], (m = 0, 1,... M-1)
Θ and φ represent the angle between the reference axis and a straight line connecting the arbitrary point and the origin at an arbitrary point when the origin and the reference axis are provided in the space as shown in FIG. E ₀ (θ, φ) is the directivity of each element, λ is the wavelength of the transmission wave, dx is the element spacing, θ _m is the phase of the transmission signal input to each element, and M is the number of elements. Yes.

Here, in order to consider one-dimensional (on the x-axis) directivity, φ = 0, the number of elements M is 2, the element spacing dx is a half wavelength λ / 2, and the level of the transmission signal input to each element If the phase difference is Δθ _m and θ ₀ = 0 and θ ₁ = Δθ _m , the directivity E (θ, φ) is expressed by the following equation.

(Equation 2)
E (θ, φ) = E ₀ (θ, φ) × [1 + exp {j (π × sin θ + Δθ _m )}]
Here, for example, the directivity E (θ, φ) when the phase difference Δθ _m of the transmission signal input to each element is 0 (in-phase), 90 degrees, and 180 degrees (reverse phase) is shown in FIG. It is expressed as That is, the directivity E (θ, φ) of the transmission wave can be changed by changing the phase difference of the transmission signal input to each element. Thereby, an obstacle in a desired direction can be detected.

  The obstacle detection device according to claim 4, wherein the transmission means sets the phase difference of the transmission signals input to the adjacent elements arranged in the array in the same phase or the opposite phase, thereby reducing the directivity of the transmission wave to a narrow angle or It is characterized by a wide angle.

  As shown in FIG. 1, when the phase difference between transmission signals input to adjacent elements is the same, the directivity E (θ, φ) is an egg shape whose front direction is the strongest with respect to the element (hereinafter, this The shape of directivity is called a narrow angle). On the other hand, when the phase difference of the transmission signal input to the adjacent element is reversed, the directivity E (θ, φ) has a butterfly shape that is weak in the front direction and strong in the lateral direction with respect to the element (hereinafter, This shape of directivity is called wide angle). Therefore, obstacles can be detected in a wide range by switching the directivity E (θ, φ) to a narrow angle or a wide angle depending on the situation.

  The obstacle detection apparatus according to claim 5, wherein the transmission unit alternately switches a phase difference of transmission signals input to adjacent elements arranged in the array between an in-phase and an anti-phase, and directivity of the transmission wave Is characterized by alternately switching between a narrow angle and a wide angle.

  In this way, obstacles can be detected in a wide range by alternately switching the directivity E (θ, φ) of the transmission wave between the narrow angle and the wide angle.

  The obstacle detection device according to claim 6, wherein the reception unit performs quadrature demodulation on the reception signals received by the elements arranged in the array, and determines the threshold value of the magnitude of the combined signal of the demodulation signals. To determine the presence or absence of a reflected wave, and before synthesizing the demodulated signals, the demodulated signals are multiplied by a predetermined complex coefficient to manipulate the phase difference between the demodulated signals. Thus, the reception directivity is controlled.

  When the received signal received by each element is quadrature demodulated, the demodulated signal is obtained in a form separated into in-phase component (I) and quadrature component (Q) signals with respect to a sine wave of each predetermined frequency. When this is expressed in a complex plane (IQ plane) composed of signals of the in-phase component (I) and the quadrature component (Q), it can be expressed as a vector of a predetermined magnitude and phase. The phase of the demodulated signal of each element varies depending on the direction of the obstacle. For example, when the demodulated signals (RxA, Rx_B) of two adjacent elements are respectively represented as vectors on the IQ plane, a phase difference Δφ is generated according to the direction of the obstacle, as shown in FIG. . The figure also shows a combined vector obtained by combining these vectors. Thus, synthesizing each demodulated signal is the same as synthesizing a vector corresponding to each demodulated signal. Here, for example, when each demodulated signal (Rx_A, Rx_B) is multiplied by Rx_B by a complex coefficient exp (−jΔφ) having a phase difference of −Δφ, Rx_B and Rx_A have the same phase as shown in FIG. Can be. The figure also shows a combined vector obtained by combining these vectors. When the magnitude of the composite vector shown in FIG. 10A is compared with the magnitude of the composite vector shown in FIG. 10B, the composite vector shown in FIG. That is, when each demodulated signal is multiplied by a predetermined complex coefficient, the magnitude of the signal obtained by synthesizing each demodulated signal changes, and as a result, it affects the threshold determination for determining the presence or absence of a reflected wave. In other words, if each demodulated signal is multiplied by the complex coefficient exp (−jΔφ), the reflected wave from the direction corresponding to the phase difference of each demodulated signal can be received most strongly. Therefore, the reception directivity can be controlled by multiplying each demodulated signal by a predetermined complex coefficient and manipulating the phase difference between the demodulated signals. Thereby, an obstacle in a desired direction can be detected.

  In addition, in this way, by determining the presence of a reflected wave based on the magnitude of a signal obtained by synthesizing each demodulated signal, the receiving sensitivity is higher than when judging based on the magnitude of the received signal of one element. Can be improved. Further, since the portion without the reflected wave is noise and has a random phase, the synthesized amplitude of the noise component is reduced by vector synthesis, so that the SN ratio in the case of threshold determination can be improved.

  The obstacle detection apparatus according to claim 7, wherein the position detection unit uses the plurality of sample points for a portion where a signal obtained by combining the demodulated signals exceeds a threshold, that is, a portion where a reflected wave exists. The phase difference of the received signal received by each element arranged in a shape is calculated as a phase difference vector reflecting the magnitude of the received signal, and based on a vector obtained by adding the phase difference vectors calculated at the plurality of sample points The average of the phase difference of the received signal is calculated, and the direction of the obstacle is calculated using the average of the phase difference.

  For example, when the magnitude of the composite signal obtained for determining whether or not there is a reflected wave in the received signal described above exceeds the threshold in the section shown in FIG. The demodulated signal of each element in can be represented on the IQ plane. From these demodulated signals, for example, as shown in the following equation, a phase difference vector Def reflecting the magnitude of the received signal of each element is calculated. In the following equation, X and Y indicate the magnitude of the signal received by each element.

(Equation 3)
Def = X × Y × exp (jΔθ)
When the phase difference vector Def is calculated at a plurality of sample points and expressed on the vector plane, for example, as shown in FIG. Then, by combining these phase difference vectors Def, a phase difference vector obtained by averaging the phase differences at the respective sample points can be obtained. In addition, since each phase difference vector reflects the magnitude of the received signal of each element, the synthesized phase difference vector more strongly reflects the phase difference vector at the sample point where the received signal is large. As described above, the direction of the obstacle can be accurately calculated by using the average received signal phase difference calculated from the combined phase difference vector.

  The obstacle detection apparatus according to claim 8, wherein the reception unit sets the phase difference of the complex coefficient to be multiplied to the demodulated signal of each element to be in phase or opposite phase with respect to adjacent elements, so that the reception directivity is narrow angle or wide angle. It is characterized by doing.

  Making the phase difference of the complex coefficients to be multiplied by the demodulated signals of two adjacent elements in phase is the same as multiplying each demodulated signal by 1. In this case, when the vector signals after complex coefficient multiplication are combined, the combined signal becomes the largest when the phase of the signal received by each element is in phase. That is, the reception directivity has a narrow angle as shown in FIG.

  On the other hand, setting the phase difference of the complex coefficient to be multiplied to the opposite phase is the same as multiplying one of the demodulated signals of two elements by 1 and multiplying the other by a complex number of phase π. In this case, when the vector signals after multiplication by complex coefficients are combined, the combined signal becomes the largest when the distance between the two elements is the half wavelength (λ / 2) of the transmission wave. This is when the phase of the signal received at is opposite. That is, the reception directivity becomes a wide angle as shown in FIG.

  Thus, reflected waves in a wide range of directions can be received by appropriately switching the reception directivity between a narrow angle and a wide angle.

  The obstacle detection device according to claim 9, wherein the reception unit narrows the reception directivity by alternately switching the phase difference of the complex coefficient to be multiplied by the demodulated signal of each element between the in-phase and the anti-phase for the adjacent elements. It is characterized by alternately switching between a corner and a wide angle. In this manner, reflected waves in a wide range of directions can be received by alternately switching the reception directivity between the narrow angle and the wide angle.

  The obstacle detection apparatus according to claim 10, wherein the reception unit determines a complex coefficient to be multiplied by the demodulated signal so that the reception directivity is the same as the directivity of the transmission wave transmitted by the transmission unit. And As described above, by synchronizing the transmission directivity and the reception directivity, an obstacle included in the directivity can be reliably detected.

  The obstacle detection apparatus according to claim 11 is characterized in that the plurality of elements arranged in the array form include at least two adjacent elements arranged in the horizontal direction with respect to the ground surface. Thereby, the position of the obstacle on the horizontal plane with respect to the ground surface can be detected. Further, by switching between transmission and reception directivities, it is possible to detect a wide angle in the horizontal direction, which is effective for wide-angle position detection applications in the horizontal direction.

  The obstacle detection apparatus according to a twelfth aspect is characterized in that the plurality of elements arranged in the array form include at least two adjacent elements arranged in a direction perpendicular to the ground surface. Thereby, the position of the obstacle on the vertical plane with respect to the ground surface can be detected. In addition, by switching between transmission and reception directivities, it is possible to detect a wide angle in the vertical direction, which is effective for wide-angle position detection in the vertical direction.

  The obstacle detection apparatus according to a thirteenth aspect is characterized in that the plurality of elements arranged in the array include at least three adjacent elements arranged in a triangle. Thus, the three-dimensional position of the obstacle can be detected by arranging the three elements in a triangular shape.

  The obstacle detection apparatus according to claim 14 is characterized in that the triangle having the three elements as apexes is a regular triangle. Thereby, the area | region enclosed by three elements can be made compact, and the size of a detection apparatus can be made small.

  The obstacle detection apparatus according to claim 15 is characterized in that one side of the equilateral triangle having the three elements as vertices is horizontal with respect to the ground surface. By switching the transmission and reception directivities for the two elements arranged in the horizontal direction, it is possible to detect a wide angle in the horizontal direction, which is effective for wide-angle three-dimensional position detection applications in the horizontal direction. is there.

  The obstacle detection apparatus according to claim 16 is characterized in that an equilateral triangle having the three elements as apexes has one side perpendicular to the ground surface. By switching the transmission and reception directivities for the two elements arranged in the vertical direction, it is possible to detect a wide angle in the vertical direction, which is effective for wide-angle three-dimensional position detection applications in the vertical direction. is there.

  The obstacle detection device according to claim 17, wherein the plurality of elements arranged in the array shape include at least four elements arranged in a square shape whose one side is horizontal to the ground surface. Features. Thus, by arranging the four elements in a square shape so that one side is horizontal to the ground surface, two pieces of positional information on the horizontal plane with respect to the ground surface and a vertical plane with respect to the ground surface The three-dimensional position of the obstacle can be detected from the above two pieces of position information. Thereby, the position of an obstacle can be detected more accurately.

  The obstacle detection apparatus according to claim 18 is characterized in that switching between the narrow angle and the wide angle of the directivity of the transmission wave in the transmission means is performed by two elements arranged horizontally with respect to the ground surface. Thereby, the position of the obstacle can be detected over a wide range in the horizontal direction.

  The obstacle detection device according to claim 19 is characterized in that switching between the narrow angle and the wide angle of the reception directivity in the reception means is performed by two elements arranged horizontally with respect to the ground surface. Thereby, the position of the obstacle can be detected over a wide range in the horizontal direction.

  An obstacle detection apparatus according to claim 20 is provided with an attachment position recording unit that records an attachment position of each element with respect to a predetermined reference position of the vehicle, and a predetermined vehicle position of the element recorded by the attachment position recording unit. Based on the attachment position relative to the reference position, the obstacle position information calculated by the position detection means is converted into obstacle position information relative to a predetermined reference position of the vehicle, and the conversion means converts the obstacle position information. Obstacle position information storage means for storing obstacle position information in association with time, and movement for recording a movement locus of a predetermined reference position of the vehicle in association with time when the vehicle is traveling A trajectory recording means, position information of the obstacle at each time stored in the obstacle position information storage means, and a movement trajectory of the predetermined reference position recorded by the movement trajectory recording means; On the basis of a predetermined reference position of the vehicle at the current time, and a recognition means for recognizing the position and shape of the obstacle around the travel route of the vehicle, and a space free of the obstacle. To do.

  As a method of recognizing the movement locus of a predetermined reference position of the vehicle (for example, the center point of the vehicle), for example, a vehicle speed sensor that detects the speed of the vehicle, a geomagnetic sensor that detects the direction of the vehicle, a gyroscope, Recognize using a sensor that detects the angle. In addition, as the attachment position information of each element with respect to a predetermined reference position of the vehicle, for example, a three-dimensional coordinate and an attitude when the vehicle center is the origin are recorded.

  Accordingly, it is possible to recognize the situation around the route on which the vehicle has traveled based on the position information of the obstacle detected while the vehicle is traveling. In addition, since the position information of the obstacle is converted into position information based on a predetermined reference position of the vehicle, for example, when an obstacle is detected by attaching elements to a plurality of locations of the vehicle such as the front and rear of the vehicle. A plurality of pieces of position information can be integrated and handled.

  The obstacle detection device according to claim 21, wherein the recognition means detects and recognizes the position and shape of an obstacle around the travel route of the vehicle that the vehicle recognizes before stopping when the vehicle stops and then travels. It is characterized by holding a space free of obstacles. Thus, when the vehicle is stopped and traveling is started again, the traveling can be started in a state in which the situation around the vehicle is grasped. Therefore, for example, when the vehicle is stopped at a position where there is an obstacle in the vicinity of the vehicle, when the driver gets on the vehicle again, the driver can be notified to alert him / her.

  An obstacle detection apparatus according to a twenty-second aspect is characterized by comprising position notification means for notifying the obstacle recognized by the recognition means. As a result, the driver can grasp obstacles around the vehicle. Moreover, even if it is out of the range where the obstacle is detected from the current location, if the obstacle is detected by then, the obstacle will be notified. Therefore, it is possible to reliably avoid contact with such an obstacle.

  The obstacle detection device according to claim 23, wherein the position notification means includes a screen, displays an image showing the vehicle on the screen, and uses the position where the image showing the vehicle is displayed as a current location to travel the vehicle. It is characterized by displaying surrounding obstacles. As a result, the driver can grasp the situation around the vehicle at a glance.

  The obstacle detection device according to claim 24 is characterized in that the position notification means additionally displays the obstacle on the screen every time the recognition means newly recognizes the obstacle. Thereby, the driver can grasp the situation around the vehicle such as the shape of the obstacle.

  The obstacle detection device according to claim 25 is characterized in that the position notification means displays an image showing the vehicle and an obstacle as a bird's eye view. As a result, the driver can easily grasp the positional relationship between the vehicle and the obstacle.

  The obstacle detection apparatus according to claim 26 includes an imaging unit that images the periphery of the vehicle, and a bird's-eye image conversion unit that converts a vehicle periphery image captured by the imaging unit into a bird's-eye image. The bird's-eye image converted by the bird's-eye image conversion means is further superimposed on the bird's-eye view, and an image showing the vehicle and an obstacle are displayed. Thus, the driver can grasp the actual situation around the vehicle and can confirm whether or not an obstacle can be accurately detected, particularly when detecting a parking space.

  The obstacle detection device of claim 27 is characterized in that the position notification means blinks the obstacle. If the detected obstacle is superimposed on the actual vehicle periphery image (bird's-eye view image), it is expected that it becomes difficult to grasp the actual situation around the vehicle. Accordingly, in claim 27, the obstacle to be displayed is blinked to prevent such a problem.

  The obstacle detection apparatus according to claim 28, wherein the position notification means displays the obstacle recognized by the recognition means with a predetermined margin added. It is also expected that the detected obstacle has some errors. Therefore, when driving while grasping the displayed obstacle, the driver may accidentally touch the obstacle, especially in a small space (for example, when the vehicle is parked backward). It is done. Claim 28 takes this into consideration. For example, when a detected obstacle is displayed, it is displayed as a figure (circle or the like) having a size that takes a detection error into consideration as an obstacle.

  The obstacle detection apparatus according to claim 29 is characterized in that the position notification means displays the distance or height from the vehicle so as to be distinguished. This allows the driver to know how far and how high the obstacle is from the vehicle. As this display method, for example, the position of the obstacle is displayed by changing the color according to the distance or according to the height.

  The obstacle detection device according to claim 30 is characterized in that the position notification means notifies only the position of an obstacle within a predetermined range from the current location of the vehicle. It may be troublesome for the driver to notify the obstacles far away from the vehicle. Claim 30 takes this into consideration.

  The obstacle detection apparatus according to claim 31, further comprising a predicting unit that predicts a travel route of the vehicle, wherein the position notification unit notifies only an obstacle around the travel route of the vehicle predicted by the prediction unit. Features. For example, when the vehicle is to be moved backward and parked, it is considered necessary for the driver to know only the situation around the travel route of the vehicle. Claim 31 takes this situation into consideration. In addition, as a method for predicting the travel route of the vehicle, for example, prediction is made based on the current speed and steering angle of the vehicle, or prediction is made based on the maximum steering angle unique to the vehicle.

  An obstacle detection apparatus according to a thirty-second aspect is characterized in that the notification means includes a switch for switching whether to notify the obstacle. This is because some drivers may think that notification of obstacles is not necessary.

  The obstacle detection apparatus according to claim 33, further comprising a braking unit that stops the vehicle when the obstacle recognized by the recognition unit approaches a predetermined distance or less where the possibility of contact with the vehicle is high. And Thus, even when the driver does not know that there is an obstacle in the immediate vicinity of the vehicle, it is possible to prevent the vehicle and the obstacle from coming into contact with each other.

  An obstacle detection apparatus according to a thirty-fourth aspect is characterized in that each of the elements is attached to a side surface of the vehicle so that a main radiation direction is directed in a direction orthogonal to a traveling direction of the vehicle. Thereby, it is possible to detect an obstacle at a long distance with respect to the side of the vehicle. For example, in a use of searching for a parking space, it is possible to search a space far away.

  An obstacle detection apparatus according to claim 35, wherein the obstacle detection device detects the obstacle at every interval equal to or less than a mileage interval that realizes a required detection accuracy, and a speed detection means that detects the speed of the vehicle. And a speed limit calculating means for calculating a speed limit of the vehicle from a transmission repetition period of the transmission wave transmitted by the transmitting means, and the speed detecting means detects the speed limit calculated by the speed limit calculating means. In the case where the speed of the vehicle to be exceeded is exceeded, a notification means for notifying that effect is provided.

  For example, when this obstacle detection device is used for recognizing a parking area for parking assistance, it is necessary to accurately detect the position of an obstacle around the vehicle. In this case, as the speed of the vehicle increases, the distance interval for detecting the position becomes rough, so that the detection accuracy of the obstacle and the parking area decreases. For this reason, the obstacle detection device according to claim 35 calculates the speed limit of the vehicle for realizing the required detection accuracy, and warns when the vehicle exceeds the speed limit. I am doing so. By this warning, the driver can accurately detect the position of the obstacle around the vehicle by setting the vehicle speed to the speed limit or less.

  The obstacle detection device according to claim 36, wherein, only when the notification means determines that the reception means has received a reflected wave from an obstacle, the obstacle speed detection means calculates the speed limit calculated by the speed limit calculation means thereafter. Then, when the speed of the vehicle detected by the speed detecting means exceeds, a notification to that effect is given.

  As described above, the notification that the speed of the vehicle has been exceeded is performed in order to cause the driver to reduce the speed of the vehicle by this notification and to accurately detect the positions of surrounding obstacles. Therefore, it is troublesome and inappropriate for the driver to perform the notification even when there is no obstacle around the vehicle. For this reason, in the obstacle detection device according to claim 36, only when it starts to detect that there is an obstacle around the vehicle, the notification for making the vehicle speed equal to or less than the speed limit is provided.

  The obstacle detection device according to claim 37, wherein the obstacle detection device detects the obstacle at every interval equal to or less than the mileage interval that realizes the required detection accuracy, and speed detection means for detecting the speed of the vehicle. And a speed limit calculating means for calculating a speed limit of the vehicle from a transmission repetition period of the transmission wave transmitted by the transmitting means, and the speed detecting means detects the speed limit calculated by the speed limit calculating means. And a speed control means for controlling the speed of the vehicle to the speed limit or less when the speed of the vehicle exceeds. As described above, when the vehicle speed is automatically controlled to be equal to or lower than the speed limit, the operation burden on the driver can be reduced.

  The obstacle detection device according to claim 38, wherein the speed control means controls the speed of the vehicle below the speed limit only after the receiving means determines that the reflected wave from the obstacle has been received. It is characterized by doing.

  As described above, the speed of the vehicle is made equal to or less than the speed limit in order to accurately detect the position of the obstacle around the vehicle. Therefore, in the obstacle detection device according to the thirty-eighth aspect, the speed of the vehicle is controlled only when it is detected that there is an obstacle around the vehicle.

  The obstacle detection device according to claim 39 is a speed detection means for detecting the speed of the vehicle, and for detecting an obstacle at an interval equal to or less than the travel distance interval for realizing the required detection accuracy, And a period calculating means for calculating a necessary position detection period from the speed of the vehicle detected by the speed detecting means, and the transmitting means is less than or equal to the position detection period calculated by the period calculating means. The transmission period of the transmission wave is controlled.

  As described above, in order to accurately detect the position of the obstacle around the vehicle during traveling, it is necessary to detect the position at a predetermined distance interval or less. In order to detect the position at a predetermined distance interval, the transmission period of the transmission wave may be controlled.

  The obstacle detection device according to claim 40, wherein the speed limit calculating means switches the directivity of the transmission wave or the reception directivity alternately between a narrow angle and a wide angle instead of the speed limit. A speed obtained by halving the speed is calculated as a speed limit.

  For example, the position detection cycle when the vehicle speed and the transmission cycle of the transmission wave are fixed is such that when the directivity of the transmission wave is alternately switched between the narrow angle and the wide angle, the position is always narrow. Is twice as large. Therefore, when the directivity or the reception directivity of the transmission wave is alternately switched between the narrow angle and the wide angle, the obstacle detection accuracy can be ensured by further reducing the speed limit by half.

  The obstacle detection device according to claim 41, wherein the period calculation unit switches the directivity of the transmission wave or the reception directivity alternately between a narrow angle and a wide angle instead of the position detection period. A period obtained by halving the detection period is calculated as a position detection period.

  Similarly to claim 40, when controlling the transmission cycle of the transmission wave, when the directivity or the reception directivity of the transmission wave is alternately switched between the narrow angle and the wide angle, in order to ensure the detection accuracy of the obstacle In addition, the position detection cycle calculated to control the transmission cycle of the transmission wave is half that when the directivity is not switched alternately.

  The obstacle detection apparatus according to claim 42, wherein the transmission means switches a phase of a transmission signal input to each element arranged in the array according to an obstacle position calculated immediately before by the position detection means. It is characterized by that.

  By using the obstacle detection apparatus according to claim 42, for example, when an obstacle is detected during traveling, the directivity of the transmission wave can be controlled following the obstacle, so that the obstacle can be accurately detected. The position can be detected.

  45. The obstacle detection apparatus according to claim 43, wherein the reception unit switches a complex coefficient to be multiplied by a demodulated signal of each element in accordance with the position of the obstacle just calculated by the position detection unit. . Thus, the reception directivity may be switched according to the position of the obstacle. Thereby, a reflected wave corresponding to the position of the obstacle can be received.

  45. The obstacle detection apparatus according to claim 44, wherein the transmitting means and the receiving means use ultrasonic waves, and the reflected waves are generated when reverberation due to transmission of the transmission waves is present in each element. When the position detecting means determines that the receiving means has received the reflected wave when reverberation due to the transmission wave being transmitted is present in each element. The calculation of the distance and direction of the obstacle is stopped.

  Even if the reverberation due to the transmission wave being transmitted is received within a certain time in each element, the reflected wave overlaps with the reverberation. For this reason, since the rising of the reflected wave cannot be detected accurately, it is difficult to accurately detect the position of the obstacle. Claim 44 takes this into consideration. Note that an area where the position of an obstacle cannot be detected accurately even when a reflected wave is received is referred to as a dead zone hereinafter.

  The obstacle detection apparatus according to a 45th aspect is characterized in that an element interval between adjacent elements arranged in the array is not more than half of the wavelength of the transmission wave.

First, in order to consider the dependency of the directivity E (θ, φ) on the element spacing d, in the above equation 1, φ = 0 (considering one dimension), and the number of elements M is set to 2 for each element. In order to set the phase difference of the input transmission signal to the same phase (0), if θ ₀ = θ ₁ , the directivity E (θ, φ) is expressed by the following equation.

(Equation 4)
E (θ, φ) = E ₀ (θ, φ) × [1 + exp {j (2π / λ) × d × sin θ}]
FIG. 19 shows the directivity E (θ, φ) with respect to the azimuth θ with respect to each element interval d (0.5λ or more) using the equation (4). As shown in the figure, when the element interval d is 0.5λ or more, a transmission wave is transmitted in the front direction of each element (hereinafter, this range is referred to as a main lobe), and the output of the transmission wave is zero. A transmission wave is transmitted in a direction greater than or equal to the direction θ _th (hereinafter, this direction is referred to as a null point) (hereinafter, this range is referred to as a grating lobe). On the other hand, when the element interval d is 0.5λ, no grating lobe is generated in the directivity of the transmission wave. Therefore, when the element interval d is larger than 0.5λ, the intensity of the transmission wave in the main lobe is weakened by the amount that power for transmitting the transmission wave is taken by the grating lobe. That is, the transmission distance of the transmission wave is reduced.

  On the other hand, on the receiving side of the reflected wave, if the element spacing d is larger than 0.5λ, the orientation of the object may not be uniquely determined depending on the phase difference of each element of the reflected wave. FIG. 20A is a diagram showing the relationship between the phase difference of each element of the reflected wave and the arrival direction (object orientation) of the reflected wave when the element interval d is 0.75λ (> 0.5λ). . In the figure, the direction of the central axis between the elements is the arrival direction θ = 0. As shown in the figure, in the range where the absolute value of the phase difference Δφ is 90 ° to 180 °, there are two candidates for the arrival direction θ of the reflected wave. As described above, there may be a plurality of candidates for the arrival direction θ because the phase difference X and the phase difference X + 2nπ (n is an integer) cannot be distinguished on the receiving side. Therefore, in such a range, the arrival direction θ of the reflected wave is not uniquely determined. That is, the position of the object cannot be determined.

  On the other hand, FIG. 5B shows the relationship between the phase difference Δφ and the arrival direction θ of the reflected wave when the element spacing d is 0.5λ. As shown in FIG. The arrival direction θ of the reflected wave can be uniquely determined for the phase difference Δφ.

  From the above, it is desirable that the element interval d is 0.5λ or less on both the transmission side and the reception side. Claim 43 takes this into consideration.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described.

  FIG. 5 is a block diagram showing the overall configuration of the obstacle detection apparatus 100 of the present embodiment. As shown in the figure, the obstacle detection apparatus 100 includes a transmission control unit 20, a reception control unit 30, elements 40A and 40B, an element attachment position storage unit 50, a travel state acquisition unit 60, and the ECU 10.

  The ECU 10 is a normal computer and includes a ROM, a RAM, a CPU, an I / O (not shown), and a bus connecting them. When detecting an obstacle, the ECU 10 instructs the transmission control unit 20 to transmit a transmission wave to the outside of the vehicle at a predetermined timing. In addition, the ECU 10 instructs the reception control unit 30 to transmit the position information of the obstacle to itself. And based on the position information on the basis of the vehicle center point of each element stored in the element attachment position storage unit 50 described later, the position information of the obstacle sent from the reception control unit 30 is The position information is converted into position information based on the center point, and stored in the RAM in association with the time. Then, based on the movement trajectory of the center point of the vehicle calculated based on the driving state acquisition unit 60 described later, the position information stored in this RAM is converted into a relative position based on the current location, and the current location is used as a reference. It recognizes what kind of obstacle is located at which position around the travel route, how much space is free of obstacles, and how much space is movable.

  The transmission control unit 20 is a part that generates a predetermined transmission signal based on a transmission instruction from the ECU 10 and outputs it to each element (40A, 40B). Specifically, as shown in FIG. 7, the transmission phase determining unit 21 and the transmission waveform generating units 22A and 22B are configured.

The transmission phase determination unit 21 determines the phase of the transmission signal input to each of the elements 40A and 40B, and instructs the transmission waveform generation units 22A and 22B. In the present embodiment, the phase of the transmission signal input to each element is determined so that the directivity of the transmission wave is alternately switched between a narrow angle and a wide angle. In this embodiment, as will be described later, the elements 40A and 40B are arranged at intervals of a half wavelength (λ / 2) with respect to the wavelength λ of the transmission wave. In this case, the two-dimensional plane ( Directivity E (θ, φ) of φ = 0) is expressed as the following equation. In the following equation, θ and φ are the angles between the straight line connecting the arbitrary point and the origin at the arbitrary point when the origin and the reference axis are provided in the space as shown in FIG. 15 and the reference axis. E ₀ (θ, φ) represents the directivity of each element, and Δθ _m represents the phase difference of the transmission signal input to each element (the phase difference of the transmission signal input to each element). Is set to Δθ _m , θ ₀ = 0 and θ ₁ = Δθ _m ).

(Equation 4)
E (θ, φ) = E ₀ (θ, φ) × [1 + exp {j (π × sin θ + Δθ _m )}]
Here, in order to narrow the directivity E (θ, φ), the phase difference Δθ _m of the transmission signal input to each element is set to 0 (in-phase), and the directivity E (θ, φ) is set to a wide angle. For this, the phase difference Δθ _m of the transmission signals input to each element may be set to 180 degrees (reverse phase). Therefore, in order to alternately switch the directivity of the transmission wave between the narrow angle and the wide angle, as shown in FIG. 11, the phase of the transmission signal input to each element may be switched alternately between the in-phase and the reverse phase. That is, the transmission phase determination unit 21 instructs the transmission waveform generation units 22A and 22B alternately to have the same phase and the opposite phase.

  Based on an instruction from the transmission phase determination unit 21, the transmission waveform generation units 22A and 22B generate a sine wave having a predetermined phase and a predetermined frequency, and input a pulse-modulated signal to each element as a transmission signal.

  As shown in FIG. 6, the elements 40A and 40B are arranged in an array at intervals of a half wavelength λ / 2 with respect to the wavelength λ of the transmission wave, and transmitted from the transmission waveform generation units 22A and 22B. A transmission wave corresponding to the transmission signal is transmitted to the outside. Specific examples of the elements 40A and 40B include an ultrasonic microphone that generates ultrasonic waves and an antenna that generates radio waves. The elements 40 </ b> A and 40 </ b> B receive a signal coming from the outside, and transmit this received signal to the reception control unit 30.

  Based on the signals sent from the elements 40A and 40B, the reception control unit 30 determines whether or not the signal is a reflected wave of an obstacle. It is a part which calculates the position of an obstacle based on. Specifically, as shown in FIG. 8, orthogonal demodulation units 31A and 31B, complex coefficient determination unit 32, multiplication units 33A and 33B, addition unit 34, amplitude calculation unit 35, threshold value determination unit 36, distance calculation unit 37, An azimuth calculation unit 38 and a position conversion unit 39 are included.

  The quadrature demodulation units 31A and 31B are parts that perform quadrature demodulation on the signals transmitted from the elements 40A and 40B. Specifically, the signals sent from the elements 40A and 40B are multiplied by a sine wave and a cosine wave of each predetermined frequency, a high-frequency component is removed by a low-pass filter, and an in-phase component (I) and a quadrature component (Q ). This operation may be performed after AD conversion, or may be AD converted after quadrature demodulation and converted to a digital value. When this quadrature demodulated signal is represented on a complex plane (IQ plane) composed of in-phase component (I) and quadrature component (Q) signals, a vector having a predetermined magnitude and phase is obtained as shown in FIG. Can be represented.

  The complex coefficient determination unit 32 is a part that determines a complex coefficient to be multiplied with the signal after orthogonal demodulation of each element. The reception directivity can be changed by the value of the complex coefficient. In this embodiment, the value of this complex coefficient is determined so as to have the same directivity as the transmission directivity. That is, the phase of the complex coefficient is alternately switched between the in-phase and the opposite phase so that the reception directivity is alternately switched between the narrow angle and the wide angle.

  Multiplying units 33A and 33B multiply each demodulated signal by the complex coefficient determined by complex coefficient determining unit 32, change the phase difference of each demodulated signal, and adder 34 performs vector addition. Thereafter, the amplitude of the signal after the vector addition is calculated by the amplitude calculation unit 35, and whether or not the amplitude is larger than the threshold is determined by the threshold determination unit 36. That is, when the amplitude of the signal after the vector addition is larger than the threshold value, it is determined that the received signal is a reflected wave from the obstacle, and the distance calculation unit 37 and the direction calculation unit 38 determine the obstacle corresponding to the reflected wave. Calculate the position. Specifically, the distance calculation unit 37 calculates the failure from the time difference between the time when the amplitude after vector addition of the received signal exceeds the threshold and the time when the transmission wave is transmitted (see FIG. 9A). Calculate the distance of an object.

  Further, the azimuth calculation unit 38 calculates the azimuth based on the phase difference of each demodulated signal in the portion where the amplitude of the signal after vector addition exceeds the threshold (see FIG. 9B). Specifically, as shown in FIG. 10, when the distance between two elements is d, the phase difference between the demodulated signals is Δφ, and the wavelength of the reflected wave is λ, the arrival direction θ of the reflected wave is It is expressed in

(Equation 5)
θ = sin ⁻¹ (Δφ × λ / (2π × d))
Substituting the wavelength λ of the reflected wave (same as the wavelength λ of the transmitted wave) and the distance d (λ / 2) between the two elements into the above equation and calculating the phase difference Δφ of each demodulated signal, The arrival direction θ can be calculated.

Here, in order to calculate the phase difference Δφ of each demodulated signal, first, the magnitude of the received signal shown in the following equation is reflected at a plurality of sample points where the amplitude of the signal after vector addition exceeds the threshold. Then, the phase difference vector Def indicating the phase difference of each demodulated signal is calculated. In the following equation, X and Y represent the intensity of each demodulated signal, and φ ₁ and φ ₂ represent the phase of each demodulated signal.

(Equation 6)
Def = X × Y × exp (j (φ ₁ −φ ₂ )) = X × Y × exp (j (Δφ))
Here, each demodulated signal Rx_A, Rx_B is represented by the sum of the in-phase component (I) and the quadrature component (Q) as shown in the following equation (see FIG. 16A). In the following expression, a + jb and c + jd are unit vectors.

(Equation 7)
Rx_A → X × exp (jφ ₁ ) = X × (a + jb) = (X × a) + j (X × b)
(Equation 8)
Rx_B → Y × exp (jφ ₂ ) = Y × (c + jd) = (Y × c) + j (Y × d)
By substituting these formulas into the above formula 6, the in-phase component Def_I and the quadrature component Def_Q of the phase difference vector Def are respectively expressed by the following formulas.

(Equation 9)
Def_I = (X × a) × (Y × c) + (X × b) × (Y × d)
(Equation 10)
Def_Q = (X × b) × (Y × c) − (X × a) × (Y × d)
Therefore, the phase difference vector Def can be calculated by substituting the components of each demodulated signal into the above formulas 9 and 10 (see FIG. 16B). Then, a phase difference vector calculated at each sample point is added to calculate a combined phase difference vector Sum_Def (see FIG. 16C), and an obstacle direction is calculated from the phase of the combined phase difference vector Sum_Def. Therefore, the phase difference Δφ of each demodulated signal is calculated. In this way, by synthesizing the phase difference vector reflecting the magnitude of the received signal, it is possible to average the phase difference having the magnitude of the received signal as a weight, and the phase difference Δφ can be accurately calculated. Based on this Δφ, the arrival direction θ of the reflected wave is calculated from (Equation 5).

  The position converting unit 39 is a part that converts the obstacle distance information calculated by the distance calculating unit 37 and the obstacle direction information calculated by the azimuth calculating unit into coordinate information indicating the position of the obstacle. In this embodiment, since the two elements 40A and 40B are used, they are converted into two-dimensional coordinates on the plane to which each element belongs. The position conversion unit 39 transmits the position information of the obstacle to the ECU 10 based on the position information request instruction from the ECU 10.

  The element attachment position storage unit 50 is a part that stores attachment position information of the elements 40A and 40B with respect to the vehicle. In the present embodiment, the three-dimensional coordinates and the posture are stored when the vehicle center point is the origin.

  The traveling state acquisition unit 60 is a part that acquires a traveling state indicating the vehicle speed and direction at each time of the vehicle from a vehicle speed sensor, a geomagnetic sensor, a gyroscope, a steering angle, and the like.

  When detecting an obstacle, the ECU 10 stores the movement locus of the center point of the vehicle in the RAM in association with the time based on the traveling state acquired from the traveling state acquisition unit 60. Further, the position information of the obstacle sent from the reception control unit 30 is converted into position information based on the center point of the vehicle, and stored in the RAM in association with the time. As described above, the position information of the obstacle is converted into the position information based on the center point of the vehicle because the elements attached to the vehicle are attached not only to the elements 40A and 40B but also to other places. This is because when detecting an obstacle, a plurality of pieces of position information are integrated and handled. Based on the movement locus of the vehicle center point stored in the RAM, the position information of the obstacle corresponding to each time stored in the RAM is converted into a position based on the current location. That is, as shown in FIG. 12, the ECU 10 recognizes the position information of the obstacle detected at each time with reference to the current time and position. Thereby, the shape of the obstacle can be recognized from the position information of the plurality of obstacles detected during the traveling. In the case of a rod-like obstacle as shown in FIG. 12 (a), it is calculated as one point and can be recognized as a rod-like obstacle. In the case of a planar obstacle as shown in FIG. 12 (b), it varies depending on movement. A point can be calculated to recognize that the obstacle is planar. Specifically, for example, when used for searching for a space at the time of parallel parking, as shown in FIG. 12C, the shape of the parked vehicle can be detected and a space that can be used for parking can be searched. Similarly, even when applied to parallel parking space search, as shown in FIG. 12 (d), the shape of the parked vehicle is detected, a space that can be used for parking is searched, and the presence / absence of space is determined and the target position setting for automatic parking is performed. Can be used. In addition, if the elements 40A and 40B are attached to the side of the vehicle so that the main radiation direction is directed in a direction orthogonal to the traveling direction of the vehicle, a far parking space can be searched.

  As described above, the obstacle detection apparatus 100 according to the present embodiment can detect not only the distance of the obstacle but also the direction by using the elements arranged in an array. That is, the position of the obstacle can be accurately detected. Further, the directivity of the transmission wave is alternately switched between the narrow angle and the wide angle by alternately switching the phase of the transmission signal input to each element between the in-phase and the opposite phase. On the other hand, regarding the reception directivity, the phase of the complex coefficient multiplied by the reception signal received by each element is alternately switched between the in-phase and the reverse phase so that the directivity is the same as the transmission directivity. As a result, obstacles can be detected in a wide range. Furthermore, since the position information of the obstacle detected during traveling is converted based on the current position, the situation of the obstacle around the traveling route can be recognized as the position with respect to the current location. Accordingly, for example, when the obstacle detection apparatus 100 is used for assisting parking, it is possible to accurately recognize the situation of obstacles around the vehicle and the space where parking and movement are possible.

(Modification 1)
In the above embodiment, in order to detect an obstacle in a wide range, the transmission / reception directivity is alternately switched between a narrow angle and a wide angle. However, the present invention is not limited to this. Sex may be controlled. Further, for example, as shown in FIG. 13, until the obstacle is detected, the directivity is alternately switched between the narrow angle and the wide angle, and when the obstacle is detected, thereafter, depending on the position of the obstacle. The directivity may be controlled. Thereby, even if the vehicle is traveling, it is possible to follow the obstacle, so that the position of the obstacle can be accurately detected.

(Modification 2)
By arranging the two elements in an array as in the above embodiment, the position of the obstacle can be calculated as a two-dimensional position on the plane to which the two elements belong. Usually, since the obstacle is located on the road, it is desirable to arrange the two elements horizontally or vertically with respect to the ground surface as shown in FIGS. When two elements are arranged horizontally with respect to the ground surface ((a) in the figure), the position of an obstacle is detected in a wide range in the horizontal direction with respect to the ground surface by switching the directivity between a narrow angle and a wide angle. be able to. Similarly, when two elements are arranged perpendicular to the ground surface ((b) in the figure), the position of the obstacle can be detected over a wide range in the direction perpendicular to the ground surface.

  Further, as shown in FIGS. 14C and 14D, the three-dimensional position of the obstacle can be detected by arranging the three elements in a triangular shape. As shown in FIG. 3C, one side of a triangle composed of three elements is arranged so as to be horizontal with respect to the ground surface, and the phase difference is set for a set of elements (elements A and B) constituting the one side. By appropriately switching the switching and directivity, the position of the obstacle can be detected in a wide range in the horizontal direction. Further, position information in the direction perpendicular to the ground surface of the obstacle can be calculated from the azimuth information detected by the set of elements A and C and the set of B and C. That is, the three-dimensional position of the obstacle can be detected. Similarly, as shown in FIG. 4D, a set of elements (elements B and C) that are arranged so that one side of a triangle constituted by three elements is perpendicular to the ground surface and that constitutes the one side. Obstacles can be detected in a wide range in the vertical direction by switching the phase difference and appropriately switching the directivity. Further, as shown in FIGS. 3C and 3D, by arranging the three elements so that the triangle formed by the three elements becomes a regular triangle, the area surrounded by the three elements is made compact. Can be reduced in size.

  Further, as shown in FIG. 14E, if four elements are arranged in a square shape so that one side is horizontal to the ground surface, a wide range in the horizontal direction can be obtained depending on the set of elements arranged horizontally. The position of the obstacle can be detected at the same time, and the position of the obstacle can be detected in a wide range in the vertical direction by the set of elements arranged vertically. In addition, by using four elements, it is possible to calculate the azimuth with two sets of A, B and C, D in the horizontal direction and A, C and B, D in the vertical direction, and synthesize the results. The position detection accuracy can be improved. In this way, since the three-dimensional position can be detected, as shown in FIG. 18, when the distance to an obstacle such as a curb is to be detected, the distance to the obstacle is accurately detected with respect to the conventional distance sensor. be able to. Further, in the case of three elements and four elements, the phase difference of only a set of horizontally arranged elements may be switched to detect a wide range only in the horizontal direction.

(Modification 3)
In the embodiment described above, the ECU 10 only recognizes the situation around the vehicle from the result of detecting the obstacle during traveling. Therefore, the situation around the vehicle recognized by the ECU 10 may be updated and displayed. Specifically, for example, the flowchart of FIG. 21 is displayed. The process shown in FIG. Further, in order to update and display the situation around the vehicle recognized by the ECU 10, it is necessary to connect a display device such as a liquid crystal display to the ECU 10.

  First, in step S11, an image showing the host vehicle is displayed on the screen, and the detection result of the obstacle currently recognized by the ECU 10 is displayed as a marker with the position where the image showing the host vehicle is displayed as the current location. . At this time, when the detection results of a plurality of obstacles are stored so far, all of them are displayed.

  Next, in step S12, it is determined whether a new obstacle has been detected. This is determined based on whether or not the position information of the obstacle is sent from the reception control unit 30. If no obstacle is newly detected (negative determination), the process returns to step S11 again. At this time, the display screen is updated according to the current location of the vehicle. On the other hand, when a new obstacle is detected (affirmative determination), in step S13, the detection result is converted into position information based on the center point of the vehicle as described above, and the RAM is associated with the time. Add to memory. Then, it returns to step S11 again, the stored detection result is added, and the display of the detection result of each obstacle memorize | stored in RAM is updated. As the number of detection results increases in this way, it is reflected on the display screen, so that the driver can easily recognize the situation around the vehicle.

  22-24 is the figure which showed the example which updated and displayed the detection result of the obstruction for every situation. FIG. 22 is a diagram showing a display example when passing through a narrow space where there are obstacles in the vicinity of both sides of the host vehicle. FIG. 22 (b) shows the actual situation of FIG. The obstacle detection results are accumulated and displayed as markers (circles). Thereby, the driver can grasp sensuously how far the vehicle is from the obstacle by checking the display screen. Therefore, even when passing through a narrow space, it can pass without touching the obstacle.

  Further, FIG. 23 is a diagram showing an example of displaying the recognition result when recognizing a parking available space. As shown in FIG. 23B, the actual situation of FIG. Obstacle detection results are cumulatively displayed with markers (circles). Accordingly, the driver can grasp whether or not the parking space is correctly recognized.

  FIG. 24 is a diagram showing an example of displaying the obstacle detection result when the vehicle is parked in parallel by moving the vehicle backward in the parking space, but the actual situation of FIG. Obstacle detection results are accumulated and displayed with markers (circles) as shown in FIG. Accordingly, the driver can park the vehicle in the parking space without contacting the parked vehicles on both sides.

(Modification 4)
In the third modification, only the image showing the host vehicle and the obstacle detection result are updated and displayed. However, in this case, there may be a case where it is difficult to grasp which actual obstacle corresponds to the displayed obstacle detection result. Therefore, the obstacle detection result may be updated and displayed on the image around the actual vehicle. Specifically, for example, the display is performed according to the flowchart of FIG. The process shown in FIG. In addition, it is necessary to install a camera for capturing images around the vehicle and connect it to the ECU 10.

  First, in step S21, the periphery of the vehicle is imaged using the camera. Next, in step S22, the captured image is converted into a bird's-eye view image. Next, in step S23, the detection result of the obstacle detected so far is displayed on the converted bird's-eye view image. At this time, an image showing the host vehicle is also displayed, and each obstacle is displayed with the display position as the current location. For example, the actual situation shown in FIG. 26A is displayed as shown in FIG.

  Next, in step S24, it is determined whether a new obstacle has been detected. If no new obstacle is detected (negative determination), the process returns to step S21 again. At this time, when the vehicle moves, the obstacle detection result is updated and displayed based on the current location. On the other hand, when a new obstacle is detected, in step S25, the detection result is converted into position information based on the center point of the vehicle as described above, and stored in the RAM in association with the time. Then, it returns to step S21 again, and the display of the detection result of the obstruction memorize | stored in RAM is updated including the memorize | stored detection result (step S21-23).

  Thus, by displaying the obstacle detection result superimposed on the bird's-eye view around the actual vehicle, it is possible to easily grasp which obstacle has been detected.

  Moreover, if a marker indicating the detection result of an obstacle is always displayed superimposed on the bird's-eye view image, the bird's-eye view image may be difficult to grasp. Therefore, the marker may be displayed blinking.

(Modification 5)
In the said modification 3, 4, it displayed with the same marker irrespective of the position of the detected obstacle (refer FIGS. 22-24, FIG. 26). Even in this case, since the image showing the host vehicle is also displayed, the driver can sensuously grasp how far the obstacle is from the vehicle. However, to make it easier to see how far the obstacle is from the vehicle, change the marker type and color depending on the location of the obstacle (distance and height from the vehicle). It may be.

(Modification 6)
When the detected obstacle is updated and displayed as in the third to fifth modifications, the detected obstacle may be displayed at a position different from the actual obstacle by the error. Therefore, when displaying the detected obstacle with a marker, a margin may be added in consideration of the detection error. That is, the marker to be displayed is enlarged. This can prevent the vehicle from accidentally contacting an obstacle.

(Modification 7)
In the said modification 3-6, it was premised on displaying the detection result of the obstruction recognized by ECU10 within the range which can be displayed on a display screen. However, as shown in FIG. 27, for example, when the vehicle is moved backward and parked in parallel, it is considered that the driver need only be able to grasp obstacles around the travel route until parking is completed. Therefore, a travel route of the vehicle may be predicted in advance, and only obstacles around the predicted travel route may be displayed. As a method of predicting the travel route of the vehicle, for example, prediction is made based on the speed and steering angle of the vehicle, or prediction is made based on the maximum steering angle unique to the vehicle.

(Modification 8)
In the above modified examples 3 to 7, all obstacles detected during traveling are displayed as long as they can be displayed on the display screen so that the driver can accurately grasp the situation around the vehicle. However, some drivers may find it cumbersome to display even obstacles far from the vehicle. Therefore, only obstacles within a predetermined range from the vehicle may be displayed. Alternatively, when an obstacle approaches within a predetermined range from the vehicle, a sound may be notified.

  In addition, even if only an obstacle within a predetermined range is notified from the vehicle, the driver may miss the notification or miss it. Accordingly, a braking device that controls braking of the vehicle may be connected to the ECU 10, and the ECU 10 may issue an instruction to the braking device to stop the vehicle when an obstacle enters the vicinity of the vehicle. This can reliably prevent the vehicle from coming into contact with the obstacle.

(Modification 9)
In the modified examples 3 to 8, the obstacle detected by the ECU 10 during traveling is updated and displayed. However, some drivers may think that it is not necessary to display the position of the obstacle. Therefore, a switch for instructing the ECU 10 whether or not to display the detected obstacle may be provided.

(Modification 10)
In the above embodiment, the position information of the obstacle detected while the vehicle is traveling is stored in the RAM. In other words, it was assumed that the vehicle was running. However, when the vehicle stops at a parking lot or the like and then travels again, there may be an obstacle in the vicinity of the vehicle. Therefore, the position information of the obstacle recognized before stopping is retained, for example, when the driver gets on the vehicle again, a sound is notified that there is an obstacle near the vehicle, or the obstacle recognized before stopping is detected. You may make it display as it is. As a result, the driver can resume traveling with peace of mind. As a premise for performing this process, the ECU 10 needs to be connected to a sensor that detects whether the vehicle engine is on or off.

(Modification 11)
For example, when an ultrasonic pulse is used as a transmission wave, the reflected wave overlaps the reverberation even if the reverberation due to the transmission wave being transmitted is received within a certain time in each element. For this reason, since the rising of the reflected wave cannot be detected accurately, it is difficult to accurately detect the position of the obstacle. Therefore, as a threshold value indicating whether or not a reflected wave has been received, a threshold value for the dead zone as shown in FIG. 28A is provided in addition to the threshold value shown in FIG. 3, and the reception level of the reflected wave is set to a predetermined threshold value for the dead zone. If it exceeds the time, it may be determined that the reflected wave has been received in the dead zone, and the information on the reflected wave may be discarded. Instead of the threshold shown in FIG. 3, a threshold obtained by increasing the threshold of the dead zone as shown in FIG. 28B may be used. As a result, the reflected wave in the dead zone is not received.
(Modification 12)
In the above embodiment, the direction of the obstacle is calculated from the phase difference Δφ of the reflected wave received by each element 40A, 40B (see Equation 5). However, instead of the phase difference Δφ, the direction of the obstacle may be calculated from the time difference between the reflected waves received by the elements 40A and 40B.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.

  When the obstacle detection device of the present invention is used for recognizing a parking area and its surroundings, for example, for parking assistance, it is necessary to accurately detect the position of the obstacle. Therefore, it is desirable to frequently transmit transmission waves and collect as many obstacle position information as possible. However, since it takes a certain amount of time to transmit the transmission wave, receive the reflected wave, and calculate the position, there is a limit to reducing the position detection period (transmission interval of the transmission wave). For this reason, in this embodiment, the speed of the vehicle is controlled so as not to exceed the speed limit calculated from the predetermined position detection cycle and the distance interval satisfying the required detection accuracy. is there.

  FIG. 17 is a block diagram showing the overall configuration of the obstacle detection apparatus 200 of the present embodiment. In addition, the same code | symbol is attached | subjected about the same components as 1st Embodiment. As shown in the figure, in the obstacle detection device 200 of the present embodiment, a vehicle speed control device 70 that controls the speed of the vehicle is connected to the ECU 10. The vehicle speed control device 70 includes, for example, a device that controls a brake pedal and an accelerator pedal. Note that the other components of the obstacle detection apparatus 200 are the same as those in the first embodiment described above, and a description thereof will be omitted.

  Regarding the operation of the obstacle detection device 200, when detecting an obstacle, the ECU 10 acquires the vehicle speed information from the traveling state acquisition unit 60, and adjusts the vehicle speed so that the vehicle speed becomes the speed limit. 70 is instructed. As a result, the required obstacle detection accuracy can be realized.

  Further, the ECU 10 controls the vehicle to a speed that is half the speed limit when the directivity is alternately switched between the narrow angle and the wide angle. This is because the position detection interval with one directivity is made the same when the directivity is switched alternately and when the directivity is not switched.

  Further, only when an obstacle is detected, the speed control may be performed after that. This is because it is not necessary to control the speed even when there are no obstacles around the vehicle.

  Moreover, you may control a position detection period (transmission interval of a transmission wave) according to the speed of the present vehicle instead of controlling a speed. In this case, the ECU 10 calculates a necessary position detection cycle from the distance interval for realizing the required detection accuracy and the current speed of the vehicle, and controls the position detection cycle. Similarly in this case, when the directivity is alternately switched between the narrow angle and the wide angle, the directivity is controlled to be a half of the calculated position detection period.

  In addition, an alarm is connected instead of the vehicle speed control device 70, and when the vehicle speed exceeds the speed limit, a notification to that effect is made and the driver is prompted to set the vehicle speed below the speed limit. You may do it. Similarly, in this case, only when an obstacle is detected, this notification may be performed after that point.

It is a figure which shows the all-element synthetic | combination directivity of a transmission wave corresponding to the phase difference of the transmission signal input into each element. It is the figure which represented on the IQ plane the demodulated signal received by each element (the figure (a)), and is the figure which showed having adjusted the phase of each signal by multiplying this signal with a complex coefficient. The figure ((a) in the figure) showing the threshold value determination of whether or not the received signal is a reflected wave of an obstacle of the signal obtained by vector addition of the signal after multiplication of the complex coefficient to each demodulated signal, and the signal after vector addition It is a figure (the figure (b)) which shows the phase difference vector of the received signal of each element computed in a plurality of sample points of the part exceeding the threshold, and the vector which compounded them. It is a figure which shows the synthetic | combination receiving directivity corresponding to the phase difference of the complex coefficient multiplied to the signal received with each element. It is a block diagram which shows the whole structure of the obstacle detection apparatus 100 of 1st Embodiment. It is a figure which shows two elements arrange | positioned at array form. 3 is a block diagram illustrating a configuration of a transmission control unit 20. FIG. 3 is a block diagram illustrating a configuration of a reception control unit 30. FIG. The figure which shows the time change of the signal which carried out vector addition of the signal after complex coefficient multiplication to each demodulated signal (the figure (a)), and the figure which shows the time change of the phase of the received signal of each element corresponding to this (the figure) (B)). It is a figure which shows that the reflected wave has arrived at 2 elements arrange | positioned by the space | interval d from (theta) direction. It is a figure which shows that the phase of the transmission signal input into each element is alternately switched between in-phase and opposite phase, and the combined directivity of the transmission wave is switched alternately between the narrow angle and the wide angle. It is a figure which shows having detected the obstruction of the vehicle side for every time during driving | running | working. It is a figure for demonstrating switching directivity according to the position of an obstruction. It is a figure which shows the example of arrangement | positioning of an element. It is the figure which showed the relationship between a reference axis and the arbitrary positions of space, in order to demonstrate synthetic | combination directivity of a transmission wave. It is a figure for demonstrating calculating the phase difference of the received signal of each element by adding the phase difference vector of a some sample point. It is a figure which shows the whole structure of the obstacle detection apparatus 200 of 2nd Embodiment. It is a figure which shows the example which detects a position in three dimensions. It is a figure which shows the directivity of a transmission wave in case element spacing d is 0.5 (lambda) or more. It is a figure for demonstrating that the position of an object is not uniquely decided by the phase difference of each element of a reflected wave when the element space | interval d is larger than 0.5 (lambda). It is the flowchart which showed the process at the time of carrying out the cumulative display of the detected obstruction. It is the figure which showed the example of a display of the detected obstruction when a vehicle passes through a narrow space. It is the figure which showed the example of a display of the detected obstruction when recognizing the parking possible space. It is the figure which showed the example of a display of the detected obstruction when moving a vehicle backward and parallel parking. It is the flowchart which showed the process at the time of displaying the detected obstruction on the bird's-eye image around a vehicle. It is the example figure which displayed the detected obstacle superimposed on the bird's-eye view image around the vehicle. It is a figure for demonstrating displaying only the obstacle of the surroundings of the driving | running | working driving | running route of a vehicle. It is the figure which showed the threshold value for discarding the reflected wave detected in the dead zone.

Explanation of symbols

100, 200 Obstacle detection device 10 ECU
DESCRIPTION OF SYMBOLS 20 Transmission control part 30 Reception control part 40A, 40B Element 50 Element attachment position memory | storage part 60 Running condition acquisition part 70 Vehicle speed control apparatus

Claims (45)

A plurality of elements installed in a vehicle and arranged in an array; and
A transmission means for inputting a transmission signal to each element arranged in the array and transmitting a transmission wave having a predetermined directivity toward the periphery of the vehicle;
Receiving means for receiving reflected waves reflected by obstacles existing around the vehicle by each element arranged in the array, and determining the presence or absence of the reflected waves;
When it is determined that the reception unit has received a reflected wave of the transmission wave transmitted by the transmission unit, a failure is determined based on a difference between a time when the reflection unit receives the transmission wave and a time when the transmission unit transmits the transmission wave. An obstacle detection apparatus comprising: position detection means for calculating a distance to an object and calculating a direction of the obstacle based on a phase difference between reflected waves received by the respective elements. A plurality of elements installed in a vehicle and arranged in an array; and
A transmission means for inputting a transmission signal to each element arranged in the array and transmitting a transmission wave having a predetermined directivity toward the periphery of the vehicle;
Receiving means for receiving reflected waves reflected by obstacles existing around the vehicle by each element arranged in the array, and determining the presence or absence of the reflected waves;
When it is determined that the reception unit has received a reflected wave of the transmission wave transmitted by the transmission unit, a failure is determined based on a difference between a time when the reflection unit receives the transmission wave and a time when the transmission unit transmits the transmission wave. An obstacle detection apparatus comprising: position detection means for calculating a distance to an object and calculating a direction of the obstacle based on a time difference between reflected waves received by the respective elements.   3. The obstacle according to claim 1, wherein the transmission unit controls directivity of the transmission wave by changing a phase of a transmission signal input to each element arranged in the array. 4. Detection device.   The transmission means makes a phase difference of transmission signals inputted to adjacent elements arranged in the array form in-phase or in-phase so that the directivity of the transmission wave is a narrow angle or a wide angle. The obstacle detection apparatus according to 1 or 2.   The transmission means alternately switches a phase difference of transmission signals input to adjacent elements arranged in the array between an in-phase and a reverse phase, and alternately switches a directivity of the transmission wave between a narrow angle and a wide angle. The obstacle detection device according to claim 1, wherein   The receiving means performs quadrature demodulation on the received signals received by the elements arranged in the array, and determines the presence / absence of a reflected wave by determining the threshold value of the combined signal of the demodulated signals. Before synthesizing the demodulated signals, the reception directivity is controlled by multiplying the demodulated signals by a predetermined complex coefficient and manipulating the phase difference between the demodulated signals. The obstacle detection device according to any one of claims 1 to 5, wherein   The position detecting means calculates a phase difference of received signals received by the elements arranged in the array at a plurality of sample points where a signal obtained by combining the demodulated signals exceeds a threshold value. And calculating the average phase difference of the received signals based on the vector obtained by adding the phase difference vectors calculated at the plurality of sample points, and using the average phase difference. The obstacle detection apparatus according to claim 6, wherein a direction of the obstacle is calculated.   The receiving means makes the phase difference of the complex coefficient multiplied by the demodulated signal of each element in-phase or opposite-phase with respect to adjacent elements, and makes the reception directivity narrow angle or wide angle. The obstacle detection device according to claim 7.   The reception means alternately switches a phase difference of a complex coefficient to be multiplied to a demodulated signal of each element between an in-phase and an opposite phase for adjacent elements, and alternately switches a reception directivity between a narrow angle and a wide angle. The obstacle detection device according to any one of claims 6 to 8.   The reception means determines a complex coefficient to be multiplied by the demodulated signal so that the reception directivity is the same as the directivity of the transmission wave transmitted by the transmission means. The obstacle detection apparatus according to 1.   The obstacle according to any one of claims 1 to 10, wherein the plurality of elements arranged in an array form include at least two adjacent elements arranged in a horizontal direction with respect to the ground surface. Object detection device.   The obstacle according to any one of claims 1 to 10, wherein the plurality of elements arranged in the array form include at least two adjacent elements arranged in a direction perpendicular to the ground surface. Object detection device.   The obstacle detection device according to claim 1, wherein the plurality of elements arranged in an array includes at least three adjacent elements arranged in a triangle.   The obstacle detection apparatus according to claim 13, wherein the triangle having the three elements as vertices is an equilateral triangle.   15. The obstacle detection apparatus according to claim 14, wherein one side of the equilateral triangle having the three elements as vertices is horizontal with respect to the ground surface. 15. The obstacle detection apparatus according to claim 14, wherein the equilateral triangle having the three elements as apexes has one side perpendicular to the ground surface.
  11. The plurality of elements arranged in the array form include at least four elements arranged in a square shape whose one side is horizontal with respect to the ground surface. The obstacle detection device according to claim 1.   18. The switching according to claim 11, 15, or 17, wherein switching between the narrow angle and the wide angle of the directivity of the transmission wave in the transmission unit is performed by two elements arranged horizontally with respect to the ground surface. The obstacle detection device described.   18. The switching between the narrow angle and the wide angle of the reception directivity in the reception means is performed by two elements arranged horizontally with respect to the ground surface. Obstacle detection device. An attachment position recording means for recording an attachment position of each element with respect to a predetermined reference position of the vehicle;
Based on the attachment position of each element recorded by the attachment position recording means with respect to a predetermined reference position of the vehicle, the position information of the obstacle calculated by the position detection means is used as an obstacle to the predetermined reference position of the vehicle. A conversion means for converting the object position information;
Obstacle position information storage means for storing the obstacle position information converted by the conversion means in association with the time;
A movement locus recording means for recording a movement locus of a predetermined reference position of the vehicle in association with time when the vehicle is traveling;
Based on the position information of the obstacle at each time stored by the obstacle position information storage means and the movement locus of the predetermined reference position recorded by the movement locus recording means, the predetermined vehicle position at the current time is determined. 20. The apparatus according to claim 1, further comprising: a recognition unit that recognizes a position and shape of an obstacle around the travel route of the vehicle with respect to a reference position, and a space without the obstacle. Obstacle detection device.   The recognizing means retains the position and shape of obstacles around the travel route of the vehicle recognized by the vehicle before stopping and the space without obstacles even when the vehicle stops and then travels. The obstacle detection device according to claim 20, wherein   The obstacle detection device according to claim 20 or 21, further comprising position notification means for notifying the obstacle recognized by the recognition means.   The position notification means includes a screen, displays an image showing the vehicle on the screen, and displays obstacles around the travel route of the vehicle with a position where the image showing the vehicle is displayed as a current location. The obstacle detection device according to claim 22.   The obstacle detection device according to claim 23, wherein the position notification unit additionally displays the obstacle on the screen every time the recognition unit newly recognizes the obstacle.   The obstacle detection apparatus according to claim 23 or 24, wherein the position notification unit displays an image and an obstacle showing the vehicle as a bird's eye view. Imaging means for imaging the periphery of the vehicle;
A bird's-eye image conversion means for converting a vehicle peripheral image captured by the imaging means into a bird's-eye image,
26. The obstacle detection device according to claim 25, wherein the position notification unit displays an image and an obstacle indicating the vehicle by further superimposing the bird's eye image converted by the bird's eye image conversion unit on the bird's eye view. .   27. The obstacle detection apparatus according to claim 26, wherein the position notification unit blinks the obstacle.   The obstacle detection device according to any one of claims 23 to 27, wherein the position notification unit displays the obstacle recognized by the recognition unit with a predetermined margin added.   The obstacle detection device according to any one of claims 23 to 28, wherein the position notification unit displays the obstacle so that a distance or a height from the vehicle can be distinguished.   The obstacle detection device according to any one of claims 22 to 29, wherein the position notification means notifies only an obstacle within a predetermined range from the current location of the vehicle. Comprising prediction means for predicting the travel route of the vehicle,
30. The obstacle detection apparatus according to claim 22, wherein the position notifying unit notifies only an obstacle around the travel route of the vehicle predicted by the prediction unit.   The obstacle detection device according to any one of claims 22 to 31, further comprising a switch for switching whether or not the notification unit notifies the position of the obstacle.   33. The vehicle according to any one of claims 20 to 32, further comprising a braking unit that stops traveling of the vehicle when an obstacle recognized by the recognizing unit approaches a predetermined distance or less that is highly likely to come into contact with the vehicle. The obstacle detection apparatus according to 1. The obstacle according to any one of claims 19 to 33, wherein each of the elements is attached to a side surface of the vehicle so that a main radiation direction is directed in a direction orthogonal to a traveling direction of the vehicle. Object detection device. Speed detecting means for detecting the speed of the vehicle;
In order to detect obstacles at intervals equal to or less than the travel distance interval that achieves the required detection accuracy, the speed limit of the vehicle is determined from the travel distance interval and the transmission repetition period of the transmission wave transmitted by the transmission means. Speed limit calculating means for calculating;
When the speed of the vehicle detected by the speed detection means exceeds the speed limit calculated by the speed limit calculation means, a notification means for notifying that is provided. The obstacle detection device according to any one of Items 1 to 34.   The notification means detects the speed detected by the speed detection means from the speed limit calculated by the speed limit calculation means thereafter only when the receiving means determines that the reflected wave from the obstacle has been received. 36. The obstacle detection device according to claim 35, wherein when the speed of the vehicle is exceeded, the fact is notified. Speed detecting means for detecting the speed of the vehicle;
In order to detect obstacles at intervals equal to or less than the travel distance interval that achieves the required detection accuracy, the speed limit of the vehicle is determined from the travel distance interval and the transmission repetition period of the transmission wave transmitted by the transmission means. Speed limit calculating means for calculating;
Speed control means for controlling the speed of the vehicle to be equal to or lower than the speed limit when the speed of the vehicle detected by the speed detection means exceeds the speed limit calculated by the speed limit calculation means; The obstacle detection device according to any one of claims 1 to 34, comprising:   The speed control means controls the speed of the vehicle below the limit speed thereafter only when the receiving means determines that the reflected wave from the obstacle has been received. The obstacle detection device described. Speed detecting means for detecting the speed of the vehicle;
In order to detect an obstacle at an interval equal to or less than the travel distance interval that achieves the required detection accuracy, a necessary position detection cycle is calculated from the travel distance interval and the speed of the vehicle detected by the speed detection means. And a cycle calculating means for
The obstacle detection apparatus according to any one of claims 1 to 34, wherein the transmission unit controls a transmission cycle of the transmission wave so as to be equal to or less than the position detection cycle calculated by the cycle calculation unit. .   When the transmission speed directivity or the reception directivity is alternately switched between a narrow angle and a wide angle, the speed limit calculation means uses a speed that is half the speed limit as a speed limit instead of the speed limit. The obstacle detection device according to claim 35, wherein the obstacle detection device calculates the obstacle detection device.   The cycle calculating means detects the cycle of the position detection cycle in half instead of the position detection cycle when the directivity of the transmission wave or the reception directivity is alternately switched between a narrow angle and a wide angle. The obstacle detection apparatus according to claim 39, wherein the obstacle detection apparatus calculates the period.   The transmission means switches a phase of a transmission signal inputted to each element arranged in the array according to the position of an obstacle calculated immediately before by the position detection means. The obstacle detection device according to any one of the above.   43. The reception unit according to claim 6, wherein the reception unit switches a complex coefficient to be multiplied by a demodulated signal of each element in accordance with the position of the obstacle just calculated by the position detection unit. Obstacle detection device. The transmitting means and the receiving means use ultrasonic waves, and when each element has reverberation due to transmission of the transmission wave, it is determined whether the reflected wave is received,
The position detecting means calculates the distance and direction of the obstacle when the receiving means determines that the reflected wave has been received when reverberation due to the transmission wave being transmitted is present in each element. 44. The obstacle detection device according to any one of claims 1 to 43, wherein:   The obstacle detection device according to any one of claims 1 to 44, wherein an interval between adjacent elements arranged in the array is less than or equal to half of a wavelength of a transmission wave.

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