JP2007132951A - Radar system for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain a detectable distance from getting short in a preceding vehicle with reduced reflection intensity, and to reduce the constraints on optical design. <P>SOLUTION: A photoreception signal, in response to light intensity of light incident into a photoreception element 82 is obtained, without emitting light from a light emitter 140, when detecting the distance, and the light is emitted from the light emitter 140, when the distance is not detected, to bring a photoreception signal component into a fixed value in the photoreception element 82. Only the noise component are thereby left, by subtracting the photoreception signal component that is brought into a fixed value, from a waveform of the photoreception signal. The noise component can be removed from the photoreception signal, by finding the noise component obtained therein by a background noise calculating circuit 99. The detectable distance is thereby prevented from becoming small, and the constraints on the optical design are also reduced, in this radar system. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention irradiates a plurality of transmission waves at least within a predetermined angle range in the vehicle width direction, and when receiving a reflected wave for each transmitted wave, generates a reception signal corresponding to the intensity of the reflected wave, The present invention relates to a vehicular radar apparatus that detects a reflecting object based on the received signal.

  Conventionally, as shown in Patent Document 1, for example, a vehicle radar device that irradiates a transmission wave such as a light wave or a millimeter wave in front of the vehicle and detects a reflected object in front of the vehicle based on the reflected wave has been proposed. ing. This type of device is applied, for example, to a device that generates an alarm by detecting that the distance from a preceding vehicle or the like has become short, or a device that controls the vehicle speed so as to maintain a predetermined distance from the preceding vehicle. And used for detection of preceding vehicles as control objects thereof.

In this vehicular radar apparatus, the irradiation direction of the laser light emitted from the laser diode is changed using a polygon mirror that is driven to rotate, and a plurality of laser lights are provided over a predetermined angular range in each of the vehicle width direction and the height direction. Irradiate. When each laser beam is reflected by the reflecting object, the reflected light is received through the light receiving lens. The received reflected light is guided to the light receiving element, and the light receiving element outputs a voltage signal corresponding to the received light intensity. The distance to the reflecting object is detected based on the time interval from when the laser light is irradiated until the voltage signal becomes equal to or higher than the reference voltage, and the vehicle width direction and the vehicle are detected based on the irradiation angle of the laser light. The position in the high direction is also detected.
JP2002-40139

  The vehicle radar device detects the distance from the host vehicle to the preceding vehicle and the speed of the preceding vehicle with the preceding vehicle as a detection target. In such a vehicular radar device, for example, when mud or snow is attached to the rear surface of the preceding vehicle, the intensity of the reflected light reflected by the preceding vehicle decreases, and the light receiving signal causes the preceding vehicle to It becomes difficult to distinguish between a received light signal component having an intensity corresponding to the reflected reflected light and a noise component generated due to various factors. As a result, there arises a problem that the detectable distance of the radar apparatus decreases.

  In order to solve this problem, the present inventors have previously used the fact that there is a rotation angle at which the laser beam is not emitted outside the casing when the polygon mirror that scans the laser beam is rotated. An application has been filed for an invention for obtaining a noise component on the assumption that the received light signal obtained at that time includes only a reflected noise component (see Japanese Patent Application No. 2002-346282).

  However, when such a method is adopted, it has been found that an angular range in which light is not emitted outside the housing has to be woven as a design requirement of the optical mechanism, which can be a great limitation in optical design.

  The present invention has been made in view of the above-described points, and can suppress a decrease in the detectable distance of a preceding vehicle whose reflection intensity has been reduced, and can reduce restrictions on optical design. An object of the present invention is to provide a vehicular radar device.

  In order to achieve the above object, in the vehicular radar apparatus according to claim 1, when the reflected wave is received by the receiving means, the received signal outputs a signal including a received signal component corresponding to the intensity of the reflected wave. In addition to the output unit (82), an electromagnetic wave output unit (140) that outputs an electromagnetic wave that saturates the output of the received signal in the received signal output unit is provided. In the noise component calculation unit, the received signal output unit is saturated at the electromagnetic wave output unit. Based on the received signal when the electromagnetic wave to be output is output, the noise component is calculated, and in the removal unit, the electromagnetic wave output unit saturates the received signal output unit from the received signal when the electromagnetic wave is not output It is characterized by removing noise components.

  As described above, when the electromagnetic wave output unit is provided, the noise component calculation unit calculates the noise component based on the reception signal when the electromagnetic wave output unit saturates the reception signal output unit. In addition, the removal unit can remove the noise component from the reception signal when the electromagnetic wave output unit does not output the electromagnetic wave that saturates the reception signal output unit.

  Thereby, it is possible to prevent the detectable distance of the radar apparatus from being lowered. Since the noise component is detected using the noise component output unit and the selection unit, it is not necessary to incorporate an angular range in which light is not emitted outside the housing as a design requirement of the optical mechanism as in the past. . Therefore, it is possible to reduce restrictions on optical design.

  For example, when the transmitting unit is a light emitting unit that outputs a light wave as a transmission wave and the receiving unit is a light receiving unit that receives the reflected light of the light wave as a reflected wave, the intensity of the reflected light of the light wave The reception signal output unit can be configured by the light receiving element (82) that generates an output corresponding to the above, and the electromagnetic wave output unit can be configured by the light emitter (140) that saturates the output of the light receiving element.

  According to the third aspect of the present invention, the reflection object detection means determines whether or not the received signal includes a received signal component that is output according to the intensity of the reflected wave when the reflected wave is received. And a switch unit (160) for transmitting the received signal at that time to the noise component calculating unit when the determining unit determines that the received signal component is not included in the received signal. It is characterized by having.

  As described above, when it is determined that there is no received signal component, it is assumed that the received signal from the receiving means is only the reflected light noise component, and the received signal at that time is input to the noise component calculation unit. Yes. For this reason, it is possible to calculate the reflected light noise component, and the removing unit can subtract the reflected light noise component from the received signal.

  In this case, as shown in claim 4, the noise component calculation unit stores the correlation of the reflected light noise corresponding to the scanning angle of the transmission wave transmitted by the transmission means, and the received signal component is not included in the received signal. Based on the correlation, the reflected light noise for each scanning angle including the scanning angle different from the scanning angle at that time can be obtained from the received signal transmitted when the determination is made.

  As described above, the reflected light noise component is calculated only when it is determined that there is no received light signal component. From the calculated reflected light noise component and the angle dependence of the reflected light noise stored in advance. The reflected light noise component for each scanning angle can be calculated. For this reason, it is possible to learn the reflected light noise component for each scanning angle without enlarging the scale occupied by the learning process and the memory for storing the learning results, as in the case of learning the reflected light noise component for each scanning angle. It becomes.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.
(First embodiment)
FIG. 1 is a system block diagram of a vehicle control device 1 to which a vehicle radar device according to an embodiment of the present invention is applied. Hereinafter, based on this figure, the detail of the control apparatus 1 provided with the radar apparatus for vehicles is demonstrated.

  The vehicle control device 1 issues an alarm when there is an obstacle in the area to be alarmed based on the detection result of the vehicle radar device, or maintains the inter-vehicle distance from the preceding vehicle at a predetermined inter-vehicle distance. Therefore, it has a function of controlling the vehicle speed.

  As shown in FIG. 1, the vehicle control device 1 is configured with a recognition / vehicle distance control ECU 3 as the center. The recognition / vehicle distance control ECU 3 mainly includes a known microcomputer having a CPU, a ROM, a RAM, an I / O, and the like, and includes various drive circuits and detection circuits. Since these hardware configurations are general, detailed description thereof is omitted.

  The recognition / vehicle distance control ECU 3 receives detection signals from a laser radar sensor 5, a vehicle speed sensor 7, a brake switch 9, and a throttle opening sensor 11 as a vehicle radar device, and an alarm sound generator 13, a distance indicator 15, a sensor Drive signals are output to the abnormality indicator 17, the brake driver 19, the throttle driver 21 and the automatic transmission controller 23. The recognition / vehicle distance control ECU 3 detects an alarm volume setting unit 24 for setting an alarm volume, an alarm sensitivity setting unit 25 for setting sensitivity in alarm determination processing, a cruise control switch 26, and an operation amount of a steering wheel (not shown). A steering sensor 27 and a yaw rate sensor 28 for detecting the yaw rate generated in the automobile are connected. The recognition / vehicle distance control ECU 3 includes a power switch 29, and starts the predetermined process when the power switch 29 is turned on.

  The laser radar sensor 5 is expressed as a block configuration shown in FIG. 2A, and includes a light emitting unit 70a, a light receiving unit 70b, a laser radar CPU 70c, and the like as main components.

  The light emitting unit 70 a includes a semiconductor laser diode (hereinafter simply referred to as a laser diode) 75 that emits pulsed laser light via a light emitting lens 71 and a scanner 72. The laser diode 75 is connected to the laser radar CPU 70c via the laser diode drive circuit 76, and emits (emits) laser light by a drive signal from the laser radar CPU 70c. Further, the polygon mirror 73 is provided in the scanner 72 so as to be rotatable about the vertical axis, and when a drive signal from the laser radar CPU 70c is input via the motor drive unit 74, the polygon mirror 73 is connected to a motor (not shown). It is rotated by the driving force. The rotational position of the motor is detected by the motor rotational position sensor 78 and output to the laser radar CPU 70c.

  The polygon mirror 73 has a substantially hexagonal frustum shape, and its six side surfaces constitute a mirror. Since the side surface tilt angle with respect to the bottom surface of each side surface is different, the polygon mirror 73 scans the laser beam so as to discontinuously scan the laser beam within a predetermined angle range in the vehicle width direction and the vehicle height direction. Can be output. The laser beam is thus scanned two-dimensionally, and the scanning pattern will be described with reference to FIG.

  FIG. 3 is a perspective view showing an irradiation area of the laser radar sensor. The emitted laser beams are emitted, for example, at equal intervals from the right end to the left end in the measurement area 121. In FIG. 3, only the pattern 122 at the right end and the left end in the measurement area 121 is shown, and the middle is omitted. It is. Moreover, although the emitted laser beam pattern 122 shows a substantially elliptical shape as an example in FIG. 3, it is not limited to this shape and may be a rectangular shape or the like. Furthermore, in addition to those using laser light, radio waves such as millimeter waves, ultrasonic waves, or the like may be used. Moreover, it is not necessary to stick to the scanning method, and any method that can measure two directions other than the distance may be used.

  As shown in FIG. 3, when the irradiation direction of the laser beam is the Z-axis, the laser beam is sequentially in the XY plane perpendicular to the Z-axis formed by the X-axis that is the vehicle width direction and the Y-axis that is the height direction Irradiated to scan. In this embodiment, the X axis is the scanning direction and the Y axis is the reference direction.

  The scan area in which the laser beam performs two-dimensional scanning is, for example, 0.08 deg × 451 points = 20 deg in the X-axis direction, and 0.7 deg × 6 lines = 4 deg in the Y-axis direction. Further, the scanning direction is from left to right in FIG. 3 for the X-axis direction, and from top to bottom in FIG. 3 for the Y-axis direction. Specifically, first, laser light is sequentially irradiated from the left to the right in the X-axis direction at intervals of 0.08 ° with respect to the first scanning line located at the top in the Y-axis direction. Thereafter, the laser beams are sequentially irradiated at intervals of 0.08 ° in the X-axis direction in the second scanning line one row below the uppermost portion in the Y-axis direction. In this manner, the laser beam is similarly irradiated to the sixth scan line, and a plurality of laser beams are irradiated for each scan line from the first scan line to the sixth scan line.

  When the above-described scan area is irradiated with laser light, when reflected light from the laser light is received, scan angles θx and θy indicating the irradiation angle of the laser light and the distance L measured are obtained. The two scan angles θx and θy referred to here are the vertical scan angle θy between the line obtained by projecting the emitted laser beam on the YZ plane and the Z axis, and the emitted laser beam is projected on the XZ plane. The angle between the line and the Z axis is defined as the horizontal scan angle θx.

  The light receiving unit 70 b of the laser radar sensor 5 is provided with a condenser lens 81 and a light receiving element 82, and a dummy circuit 83 and a selector 84. The condensing lens 81 condenses laser light reflected by an object (not shown). When receiving the light, the light receiving element 82 outputs a voltage (light reception signal) corresponding to the intensity of the received light.

  The dummy circuit 83 is formed by RC, for example, and is configured with the same impedance as the light receiving element 82. The selector 84 selects a connection source to which the amplifier circuit 85 disposed at the subsequent stage of the light receiving unit 70b is connected. The light receiving element 82 is connected to the select 1 provided in the selector 84, and the select 2 is a dummy. The circuit 83 is connected.

  With these configurations, the case where the connection source of the amplifier circuit 85 is the light receiving element 82 and the case where the connection source is the dummy circuit 83 can be selected. That is, when the selector 84 is set to select 1, the light receiving signal is output to the amplifier circuit 85, and when the selector 84 is set to select 2, the light receiving signal is not output, and the output of the dummy circuit 83, specifically, the dummy circuit 83 is set. A signal carrying only the received electromagnetic wave noise or the like is output to the amplifier circuit 85.

  The selector 84 is supplied with an LD drive signal from the laser radar CPU 70. Based on the LD drive signal, the selector 84 is set to select 1 when distance detection is performed, and the distance detection is performed. Select 2 is set when no operation is performed.

  The light reception signal output from the light receiving element 82 and the output signal from the dummy circuit 83 are amplified by an amplifier 85, and then a first detection circuit 86 for detecting a reflection object based on each light reception signal, and a predetermined number of light reception signals. The signals are integrated and input to a second detection circuit 90 that detects a reflecting object based on the integrated signal. Hereinafter, configurations and operations of the first detection circuit 86 and the second detection circuit 90 will be described.

  FIG. 2B shows an example of the circuit configuration of the first detection circuit 86. As shown in this figure, the first detection circuit 86 calculates a distance L to the reflecting object based on the comparator 87 that compares each received light reception signal and the reference voltage, and the output of the comparator 87. And a time measuring circuit 88.

  The comparator 87 compares the light reception signal output from the amplifier 85 with a reference voltage, and outputs a comparison signal to the time measurement circuit 88 when the light reception signal is larger than the reference voltage.

  The time measuring circuit 88 obtains a time interval between light reception and light emission from the light emission time of the laser light and the light reception time of the reflected laser light. That is, as shown in the output of the laser beam and the light reception signal during light emission shown in FIG. 4A, the time interval from the light emission time t0 to the time tp at which the light reception signal reaches the peak value is obtained.

  Specifically, since the laser light emission time t0 is such that the LD drive signal output from the laser radar CPU 70c to the laser diode drive circuit 76 is input to the time measurement circuit 88, the LD drive signal Detected.

  The time tp when the light reception signal reaches the peak value is detected based on the comparison signal from the comparator 87 input to the time measurement circuit 88. The detection method of this time tp is demonstrated with reference to the received light signal waveform shown in FIG.4 (b).

  First, as shown in FIG. 4B, a rise time (t11, t21) when the received light signal exceeds the reference voltage V0 and a fall time (t12, t22) when the received light signal falls below the reference voltage V0 are detected. Then, based on these rise time and fall time, a time tp at which the peak value occurs is calculated.

  Here, in FIG. 4B, received light signals based on two reflected lights having different intensities are indicated by curves L1 and L2. In FIG. 4B, a curved line L1 indicates a received light signal of reflected light having a relatively high intensity, and a curved line L2 indicates a received light signal of reflected light having a relatively low intensity.

  As shown in FIG. 4B, the received light signal corresponding to the intensity of the reflected light has a left-right asymmetric shape, and the degree of asymmetry increases as the amplitude of the received light signal increases. Therefore, for example, the time measurement circuit 88 obtains a time interval (Δt1, Δt2) between the rise time (t11, t21) and the fall time (t12, t22), which is a parameter corresponding to the amplitude of the received light signal. Then, the peak value occurrence time tp is calculated based on the rise time (t11, t21) and the fall time (t12, t22) while taking the time interval (Δt1, Δt2) into consideration.

  After calculating the peak value generation time tp of the voltage signal in this way, as shown in FIG. 4A, the time difference Δt between the time t0 when the laser light is emitted and the peak value generation time tp can be obtained. The time difference Δt between the laser light emission time t0 and the peak value generation time tp is encoded into a binary digital signal and then output to the laser radar CPU 70c.

  Next, the second detection circuit 90 will be described. FIG. 2C shows an example of the circuit configuration of the second detection circuit 90. As shown in this figure, the second detection circuit 90 includes an analog / digital (A / D) conversion circuit 91. The light reception signal output from the amplifier 85 is input to the A / D conversion circuit 91 and converted into a digital signal. The received light signal converted into the digital signal is input to the storage circuit 93 and stored. The light-receiving signal to be digitally converted is a signal output from the amplifier circuit 85 until a predetermined time (for example, 2000 ns) elapses from the laser light emission time t0. Then, in the A / D conversion circuit 91, as shown in FIG. 5, the light reception signal is divided into N sections at a predetermined time interval (for example, 10 ns), and the average value of the light reception signals in each section is a digital value. Convert to

  The integration range designation circuit 95 generates a predetermined number of received light signals corresponding to a predetermined number of laser beams irradiated adjacently in the X-axis direction from among the received light signals stored in the storage circuit 93, and the subsequent integration circuit 97. To output. The range of the received light signal to be integrated specified by the integration range specifying circuit 95 will be described with reference to FIGS.

  FIG. 6 shows the relationship between the irradiation area of the laser beam and the preceding vehicle 130 that is the detection target object. In FIG. 6, only the irradiation area for one scan line is shown for the sake of simplicity.

  The preceding vehicle 130 shown in FIG. 6 includes a reflector having a high reflection intensity with respect to the laser beam on the rear surface thereof, and the vehicle body has a relatively high reflection intensity, although not as much as the reflector. Therefore, normally, the intensity of the reflected light reflected by the preceding vehicle 130 is sufficiently high, and the received light signal by the reflected light also has a magnitude exceeding the reference voltage V0 as shown in FIGS. 4 (a) and 4 (b). . However, for example, when mud, snow, or the like adheres to the rear surface of the preceding vehicle 130, the intensity of reflected light reflected by the preceding vehicle 130 decreases. Therefore, the light reception signal corresponding to the reflected light reflected by the preceding vehicle 130 may not exceed the reference voltage V0. When the light reception signal does not exceed the reference voltage V0, the preceding vehicle 130 cannot be detected based on the individual light reception signals. Furthermore, since the intensity of the reflected wave decreases as the distance between the preceding vehicle 130 and the preceding vehicle 130 increases, it becomes difficult to detect the preceding vehicle 130 that is separated by a predetermined distance or more based on the individual light reception signals.

  For this reason, in the present embodiment, a plurality of light reception signals are integrated to amplify the light reception signal due to the reflected wave of the preceding vehicle so that a reflected wave having a low intensity can be detected. The integration range specifying circuit 95 specifies the received light signal to be integrated.

  Here, regarding the number N of the received light signals to be integrated, the length W in the vehicle width direction of the detection target object, the detection distance L0 targeted by the detection target object, and the beam step angle θ in the vehicle width direction of the laser light. It is preferable to set based on this. That is, the number N of received light signals to be integrated is set so that the irradiation range of the predetermined number of transmission waves corresponds to the length W in the vehicle width direction of the detection target object at the target detection distance L0. This relationship is expressed by the following formula.

(Equation 1)
N = W / (L0 × tan θ)
When the number N of light reception signals to be integrated is set in this way, all of the integrated light reception signals are output when the reflected wave from the detection target object is received in the distance range with the target detection distance L0 as the upper limit. There will always be a combination of received light signals. In this case, since only the received light signal including the received signal component corresponding to the intensity of the reflected wave can be integrated, the detection sensitivity of the reflected wave can be efficiently improved based on the integrated signal.

  In the example shown in FIG. 6, the width of the preceding vehicle as the detection target is about 1.8 m, the target detection distance is 80 m, and the beam step angle in the vehicle width direction of the laser light is 0.08 deg. The number of received light signals to be integrated was set to 16.

  In addition, in the integration range specifying circuit 95, the integration circuit 97 calculates an integration signal of 16 received light signals, the comparison processing in the comparator 103 in the subsequent stage, the linear interpolation processing in the interpolation circuit 109, and the time difference in the time measurement circuit 111. The range of the received light signal to be integrated is moved at time intervals at which Δt calculation processing is completed. That is, as shown in FIG. 7, assuming that a number from 1 to 451 is assigned to the received light signal in response to the laser light irradiated 451 times so as to scan from left to right in the X-axis direction, First, the integration range designation circuit 95 designates the 1st to 16th received light signals as the range of received light signals to be integrated. When the time interval elapses, the 2nd to 17th received light signals are designated as the range of received light signals to be integrated. In this way, the integration range designation circuit 95 moves the range of the received light signal to be integrated while shifting the received light signal one by one. In this way, it is possible to minimize the decrease in angular resolution due to the integrated signal while integrating the 16 received light signals.

  That is, when the received light signal output from the light receiving element 82 is divided into 16 pieces and the integrated signal is obtained, the detection sensitivity of the reflected light can be improved. However, it will drop significantly. On the other hand, as described above, if the range of the received light signal to be integrated is shifted by one received light signal, the decrease in angular resolution can be suppressed.

  Sixteen received light signals belonging to the range specified by the integration range specifying circuit 95 are read from the storage circuit 93 and output to the integration circuit 97. As shown in FIG. 8A, the integration circuit 97 integrates 16 received light signals that have been converted into digital signals.

  At this time, when all of the 16 light reception signals include the light reception signal component S corresponding to the reflected wave from the same reflecting object, the light reception signal component S is only the same time from the emission time of the laser light. Appears at the elapsed time. Accordingly, the light reception signal component S0 in the integrated signal is obtained by amplifying the light reception signal component S of each light reception signal by 16 times.

  On the other hand, since the noise component N included in each light reception signal is basically randomly generated by external light or the like, even if 16 light reception signals are integrated, the noise component N0 is √16 = 4 It is only amplified by a factor of two. Therefore, by calculating the integration signal by the integration circuit 97, the ratio (S / N ratio) between the light reception signal component S0 and the noise component N0 is improved four times.

  For this reason, even if the light reception signal component S included in each light reception signal is small and difficult to distinguish from the noise component N, the reflected light is reflected based on the amplified light reception signal component S0 by using the integrated signal described above. An object can be detected.

  In FIG. 2C, the switching circuit 100 plays a role of switching the output destination of the integrating circuit 97 to the comparator 103 and the background noise calculating circuit 99. The background noise calculation circuit 99 is an integration circuit when the selector 2 of the selector 84 is set, that is, when distance detection is not performed and a signal obtained by amplifying the output signal of the dummy circuit 83 is output from the amplifier 85. Based on the integrated signal output from 97, a noise component to be superimposed on the received light signal is calculated.

  In this embodiment, while rotating the polygon mirror 73 provided with six mirrors having different surface tilt angles on the outer periphery, 451 laser beams are reflected on the respective mirrors, so that the laser beams are emitted in the X-axis and Y-axis directions. Scanning. For this reason, for example, when the six mirrors are switched by the rotation of the polygon mirror 73, it is a period during which distance detection is not performed. Therefore, during that period, the selector 84 is set to select 2, and the switching circuit 100 is The output destination of the integration circuit 97 is switched to the background noise calculation circuit.

  At this time, since the signal integrated in the integration circuit 97 is the output signal of the dummy circuit 83, the light reception signal component S corresponding to the reflected wave from the reflecting object is not included. Since the impedance of the dummy circuit 83 is set to be equal to that of the light receiving element 82, the dummy circuit 83 receives electromagnetic noise or the like equivalent to that of the light receiving element 82 and is superimposed on the light receiving element of the light receiving element 82. Only the noise component is included in the output signal. For this reason, the integration signal output from the integration circuit 97 is obtained by integrating only the noise component N. Therefore, the S / N ratio of the integrated signal can be further improved by removing this noise component N from the integrated signal obtained by amplifying and integrating the light reception signal of the light receiving element 82 by the subtracting circuit 101 described later. .

  Note that it is preferable to emit laser light from the light emitting unit 70a even during a period in which this distance detection is not performed. This is because when the laser beam is actually emitted, electromagnetic wave noise is generated by the emission of the laser beam and may be superimposed on the received light signal.

  Further, when the laser beam is not irradiated on the scan area shown in FIG. 3, a plurality of integration signals are output from the integration circuit 97. The background noise calculation circuit 99 averages the plurality of integrated signals and calculates an averaged integrated signal. As the averaging process, a plurality of integrated signals may be simply averaged or may be calculated by a weighted average process. As described above, by averaging the integrated signal of the received signal by the noise component N, a regular noise component appears characteristically in the averaged integrated signal.

  That is, although the noise component superimposed on the light reception signal is basically generated randomly, some of the noise component is regular due to the influence of the clock pulse of the laser radar CPU 70c or the electromagnetic wave noise caused by the emission of the laser beam. There is also a noise component. The noise component having such regularity is more emphasized than the random noise component as the averaging process is repeated. This regular noise component is always included in the integrated signal. Therefore, a noise component is obtained by performing an averaging process in the background noise calculation circuit, and by removing the averaged noise component from the integrated signal, the regular noise component is reliably removed from the integrated signal. It becomes possible to do.

  The subtracting circuit 101 shown in FIG. 2C subtracts the noise component calculated by the background noise calculating circuit 99 from the integrated signal output from the integrating circuit 97 when the laser beam is irradiated on the scan area. To do.

  The integrated signal from which the noise component has been subtracted by the subtraction circuit 101 is compared with the threshold value Vd output from the threshold value setting circuit 105 in the comparator 103. This threshold value Vd is a value corresponding to the reference voltage V0 described in FIG.

  FIG. 9 is a diagram showing a state in which each digital value of the integrated signal is calculated discretely at a predetermined time interval. As shown in this figure, when each digital value is calculated discretely at a predetermined time interval, each digital value is compared with a threshold value corresponding to the reference voltage V0. At this time, for example, when the values of the digital values Db and Dc are larger than the threshold value, the comparison result is output to the interpolation circuit 109.

  In the interpolation circuit 109, the rising time t1 and the falling time t2 that are estimated to cross the threshold value are obtained by linear interpolation. That is, assuming a straight line connecting the digital value Db exceeding the threshold and the immediately preceding digital value Da, the time corresponding to the intersection of the straight line and the threshold is obtained, and this is set as the rise time t1. Similarly, a straight line connecting the digital value Dc exceeding the threshold and the digital value Dd immediately after that is assumed. Thus, even if the digital value of the integrated signal can be obtained only discretely at a predetermined time interval, the interval is interpolated. Then, by obtaining the time corresponding to the intersection of the assumed straight line and the threshold value V0, the rising time t1 indicating when the digital value of the integrated signal exceeds the threshold value V0 and the falling time indicating when it falls below the threshold value V0 t2 is determined.

  The time measuring circuit 111 performs the same processing as the time measuring circuit 88 in FIG. 2B, and as shown in FIG. 8B, the light receiving signal component S is based on the rising time t1 and the falling time t2. Is calculated, a time difference Δt between the laser light emission time and the peak value generation time is calculated, and a signal indicating this is output to the laser radar CPU 70c.

  The laser radar CPU 70c calculates the distance to the reflecting object from the time difference Δt input from the time measurement circuits 88 and 111, and creates position data based on the distance and the corresponding scan angles θx and θy of the laser beam. Specifically, from the distance and scan angles θx and θy, the laser radar center is the origin (0, 0, 0), the vehicle width direction is the X axis, the vehicle height direction is the Y axis, and the vehicle forward direction is the Z axis. The position data of the reflecting object in the XYZ rectangular coordinate system is obtained. Then, the position data in the XYZ orthogonal coordinate system is output to the recognition / vehicle distance control ECU 3 as distance measurement data.

  When calculating the distance to the reflecting object based on the integrated signal, the scan angle θx of the laser beam corresponding to the integrated signal is the laser at the center position of the plurality of laser beams corresponding to the integrated plurality of received light signals. It is assumed that the light scan angle θx.

  The recognition / vehicle distance control ECU 3 recognizes an object based on the distance measurement data from the laser radar sensor 5, and adjusts the brake driver 19, the throttle driver 21, and the automatic according to the situation of the preceding vehicle obtained from the recognized object. A so-called inter-vehicle distance control is performed in which the vehicle speed is controlled by outputting a drive signal to the transmission controller 23. In addition, an alarm determination process for alarming when a recognized object exists in a predetermined alarm area for a predetermined time is also performed at the same time. As the object in this case, a front vehicle traveling in front of the own vehicle, a front vehicle stopped, or the like is applicable.

  The internal configuration of the recognition / vehicle distance control ECU 3 will be briefly described as a control block. The distance measurement data output from the laser radar sensor 5 is sent to the object recognition block 43. In the object recognition block 43, based on the three-dimensional position data obtained as distance measurement data, the center position (X, Y, Z) of the object and the size of the object (W, W, depth D, height H, etc.) , D, H). Further, based on the temporal change of the center position (X, Y, Z), the relative speed (Vx, Vy, Vz) of the object with respect to the vehicle position is obtained. Further, in the object recognition block 43, the object is a stop object from the vehicle speed (own vehicle speed) output from the vehicle speed calculation block 47 based on the detection value of the vehicle speed sensor 7 and the above obtained relative speed (Vx, Vy, Vz). Whether it is a moving object or not is identified. Based on the identification result and the center position of the object, an object that affects the traveling of the host vehicle is selected, and the distance is displayed on the distance indicator 15.

  Further, the steering angle is calculated by the steering angle calculation block 49 based on the signal from the steering sensor 27, and the yaw rate is calculated by the yaw rate calculation block 51 based on the signal from the yaw rate sensor 28. A curve radius (curvature radius) calculation block 57 calculates a curve radius (curvature radius) R based on the vehicle speed from the vehicle speed calculation block 47, the steering angle from the steering angle calculation block 49, and the yaw rate from the yaw rate calculation block 51. calculate. Then, the object recognition block 43 determines the probability that the object is a vehicle, the probability that the vehicle is traveling in the same lane as the vehicle, and the like based on the curve radius R and the center position coordinates (X, Z). The sensor abnormality detection block 44 detects whether or not the data obtained by the object recognition block 43 is an abnormal range value. If the data is an abnormal range value, the sensor abnormality display unit 17 displays that fact. Is made.

  On the other hand, in the preceding vehicle determination block 53, data on the preceding vehicle is selected from various data obtained from the object recognition block 43, and the distance Z and the relative speed Vz in the Z-axis direction with respect to the preceding vehicle are extracted. Then, the inter-vehicle distance control unit and the alarm determination unit block 55 include the distance Z to the preceding vehicle, the relative speed Vz, the setting state of the cruise control switch 26, the depression state of the brake switch 9, the opening degree from the throttle opening sensor 11, and Based on the sensitivity set value by the alarm sensitivity setting unit 25, it is determined whether or not an alarm is issued if the alarm is determined, and the content of the vehicle speed control is determined if the cruise is determined. As a result, if an alarm is required, an alarm generation signal is output to the alarm sound generator 13. If the cruise is determined, a control signal is output to the automatic transmission controller 23, the brake driver 19 and the throttle driver 21 to perform necessary control. When these controls are executed, necessary display signals are output to the distance indicator 15 to notify the driver of the situation.

  As described above, in this embodiment, the light reception signal of the light receiving element 82 and the output signal of the dummy circuit 83 are amplified by the amplifier 85 and then input to the second detection circuit 90. For this reason, when distance detection is not performed, a noise component superimposed on the light reception signal of the light receiving element 82 can be obtained based on the output signal of the dummy circuit 83. Therefore, distance detection can be performed based on a signal obtained by removing the noise component from the light reception signal of the light receiving element 82.

  Thereby, it is possible to prevent the detectable distance of the radar apparatus from being lowered. Since the noise component is detected using the dummy circuit 83 and the selector 84, it is not necessary to incorporate an angular range in which light is not emitted outside the casing as a design requirement of the optical mechanism as in the conventional art. Therefore, it is possible to reduce restrictions on optical design.

(Second Embodiment)
A second embodiment of the present invention will be described. In the present embodiment, the configuration of the light receiving unit 70b of the laser radar sensor 5 is changed with respect to the first embodiment, and the other configurations are the same. Therefore, only different portions will be described.

  FIG. 10 shows a block configuration of the laser radar sensor 5 provided in the vehicle control apparatus of the present embodiment. As shown in this figure, the light receiving unit 70b in the laser radar sensor 5 of this embodiment eliminates the dummy circuit 83 and the selector 84 shown in the first embodiment, and the light reception signal of the light receiving element 82 is directly input to the amplifier 85. This is different from the first embodiment in that a light emitter 140 made of an LED or the like is disposed in the vicinity of the light receiving element 82.

  According to such a configuration, it is possible to irradiate the light receiving element 82 with strong light by emitting light with the light emitter 140. For this reason, it is possible to saturate the light receiving element 82, and even if some light is incident on the light receiving element 82 during light emission by the light emitter 140, the output of the light receiving element 82 does not respond to the incident light. That is, the received light signal component is a constant value in a saturated state.

  Therefore, in this embodiment, when the distance detection is performed, the light emitter 140 does not emit light, but a light reception signal corresponding to the intensity of light incident on the light receiving element 82 is obtained, and when distance detection is not performed, the light emission is performed. The body 140 emits light so that the light receiving signal component in the light receiving element 82 has a constant value. As a result, if a light reception signal component having a constant value is subtracted from the waveform of the light reception signal when distance detection is not performed, only the noise component remains. Then, by obtaining the noise component obtained at this time by the background noise calculation circuit 99, it is possible to remove the noise component from the received light signal, and it is possible to obtain the same effect as in the first embodiment.

  In addition, although the example which provides the light-emitting body 140 was demonstrated here, the light receiving element 82 will be in an input light saturation state passively so that sunlight from the outside may enter when distance detection is not performed. It is also possible to create and use it. As described above, when DC light such as sunlight is incident on the light receiving element 82, the shot noise increases. However, since the stationary noise does not change, the stationary noise cannot be detected due to the influence of the shot noise. Absent.

(Third embodiment)
A third embodiment of the present invention will be described. In the present embodiment, the configuration of the light receiving unit 70b of the laser radar sensor 5 is changed with respect to the first embodiment, and the other configurations are the same. Therefore, only different portions will be described.

  FIG. 11 shows a block configuration of the laser radar sensor 5 provided in the vehicle control device of the present embodiment. As shown in this figure, the light receiving unit 70b in the laser radar sensor 5 of this embodiment eliminates the dummy circuit 83 and the selector 84 shown in the first embodiment, and the light reception signal of the light receiving element 82 is directly input to the amplifier 85. This is different from the first embodiment in that a switching element 150 such as a transistor is arranged in a power supply line for flowing a bias current to the light receiving element 82.

  According to such a configuration, it is possible to control on / off of supply of a bias current to the light receiving element 82 based on on / off of the switching element 150.

  The magnitude of the light reception signal (output voltage) with respect to the intensity of the incident light of the light receiving element 82 varies greatly depending on whether or not a bias current is supplied. When the bias current is not supplied, the light receiving element 82 Even if light is incident on the light receiving signal, the received light signal has a remarkably reduced waveform.

  Therefore, in the present embodiment, when the distance is detected, the switching element 150 is turned on so that a bias current is supplied to the light receiving element 82, so that a light receiving signal having high responsiveness can be obtained from the light receiving element 82. When the distance detection is not performed, the switching element 150 is turned off so that the bias current is not supplied to the light receiving element 82, so that the light reception signal component from the light receiving element 82 is compared with the case where the bias current is supplied. Try to have a small value. Thereby, a noise component can be extracted from the waveform of the received light signal when distance detection is not performed. Then, by obtaining the noise component obtained at this time by the background noise calculation circuit 99, it is possible to remove the noise component from the received light signal, and it is possible to obtain the same effect as in the first embodiment.

(Fourth embodiment)
A fourth embodiment of the present invention will be described. In each of the above embodiments, the method for learning the stationary noise generated inside the laser radar sensor 5 has been described. However, in this embodiment, the stationary situation outside the laser radar sensor 5 is also considered as noise and learned. Remove it.

  For example, in a situation where there is a cover glass or the like immediately before the laser radar sensor 5, there is not only reflected light from the preceding vehicle that is originally the target, but also reflected light components from the cover glass and the like, which are incident on the light receiving element 82. May be. Such a reflected light component from the cover glass or the like can be regarded as noise for the purpose of detecting the distance to the preceding vehicle.

  Therefore, if the integrated signal obtained when there is no received light signal component is input to the background noise calculation circuit 99, the reflected light component from the cover glass or the like can be learned as the reflected light noise component.

  The reflected light noise from the cover glass or the like varies depending on the scanning direction of the emitted light, and thus needs to be removed for each scanning direction. However, there are hundreds of scanning angles, and it is not practical to learn all of them for each scanning angle because the scale occupied by the learning process and the memory for storing the learning results become enormous.

  For this reason, the present inventors show that the angle dependency of the reflected light noise component from the cover glass or the like is gentle, and the reflected light noise component changes depending on the state of the cover glass or the like, but the angle dependency does not change much. No, the noise inside the laser radar sensor 5 has no angle dependence, and it has been found that only the representative points need to be learned. In the present embodiment, the reflected light noise is obtained based on such knowledge and removed.

  FIG. 12 shows a block configuration of the laser radar sensor 5 provided in the vehicle control apparatus of the present embodiment. Hereinafter, the laser radar sensor 5 of the present embodiment will be described with reference to this figure. In the present embodiment, the circuit configuration of the laser radar sensor 5 is changed with respect to the first embodiment. Are the same, only the different parts will be described.

  As shown in FIG. 12, the light receiving unit 70b in the laser radar sensor 5 of this embodiment eliminates the dummy circuit 83 and the selector 84 shown in the first embodiment, and the light reception signal of the light receiving element 82 is directly input to the amplifier 85. The first embodiment differs from the first embodiment in that a switching element 160 controlled by an output indicating the comparison result of the comparator 103 is provided instead of the switching circuit 100.

  Therefore, the integrated signal of the integrating circuit 97 is always input to the subtracting circuit 101, and the integrated signal from which the noise component is subtracted by the comparator 103 is smaller than the threshold value V0 output from the threshold setting circuit 105, When it is determined that there is no light reception signal component, the switching element 160 is turned on, and the integrated signal is input to the background noise calculation circuit 99. Therefore, the background noise calculation circuit 99 calculates the reflected light noise component from the integrated signal when it is determined that there is no received light signal component, and stores it in the memory according to the scanning angle at that time. ing.

  Further, the background noise calculation circuit 99 of the present embodiment stores the angle dependency of reflected light noise. Therefore, the reflected light noise component calculated from the integrated signal when it is determined that there is no received light signal component is the reflected light noise of the representative point, and from the angle dependency of the reflected light noise and the reflected light noise of the representative point, The reflected light noise component for each scanning angle is calculated.

  As described above, when it is determined that there is no light reception signal component, it is determined that the light reception signal from the light receiving element 82 is only the reflected light noise component, and the integrated signal at that time is input to the background noise calculation circuit 99. To be. For this reason, the reflected light noise component can be calculated, and the subtracted circuit 101 can subtract the reflected light noise component from the integrated signal.

  Further, the reflected light noise component is calculated only when it is determined that there is no received light signal component. Then, from the calculated reflected light noise component and the angle dependency of the reflected light noise stored in advance, the reflected light noise component for each scanning angle is calculated including the scanning angle different from the determined determination time. It has become. For this reason, it is possible to learn the reflected light noise component for each scanning angle without enlarging the scale occupied by the learning process and the memory for storing the learning results, as in the case of learning the reflected light noise component for each scanning angle. It becomes.

  Note that information from a dirt monitor or a detection sensor such as rain, fog, snow, etc., provided separately in the laser radar sensor 5 is input to the background noise calculation unit 99 regarding the occurrence of a change in the situation such as the cover glass becoming dirty. It is also possible to use it for calculating noise components.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the gist of the present invention.

  (1) The configurations shown in the first to fourth embodiments can be arbitrarily combined. For example, a laser radar sensor capable of efficiently obtaining both internal and external noise components of the laser radar sensor 5 by combining the configurations shown in the first to third embodiments and the structure shown in the fourth embodiment. 5 can be set.

  (2) In the above-described embodiment, the first detection circuit 86 and the second detection circuit 90 detect the reflection object based on the individual light reception signals and reflect the reflection object based on the integrated signal obtained by integrating the plurality of light reception signals. An example in which detection is performed independently has been described.

  However, when a reflecting object is detected based on the individual light reception signals, that is, when it is detected that the individual light reception signals have an amplitude greater than the reference voltage V0, the laser radar CPU 70c or the first detection circuit 80 is detected. Accordingly, the integration range specifying circuit 95 may receive information for specifying the light reception signal such as the number of the light reception signal, and the light reception signal may be excluded from the integration target light reception signals.

  The reason why the integrated signal of the received light signal is used is that the reflected object can be detected even if each received light signal does not have an intensity (amplitude) large enough to identify the reflected object. Because. Therefore, if each received light signal has an intensity (amplitude) large enough to detect a reflecting object, there is no need to obtain an integrated signal in the first place. Furthermore, the angle resolution is improved when the reflecting object is detected based on the individual light reception signals, compared to when the reflecting object is detected based on the integrated signal. For this reason, if a reflective object can be detected by each received light signal, distance measurement data related to the reflective object should be calculated based on the detection result.

  In addition, by setting the target reception signal range for light reception signals excluding light reception signals with sufficiently large amplitude to detect reflective objects, the calculation processing amount can be reduced and the calculation time can be shortened. It becomes possible.

  (3) In the above-described embodiments, the first detection circuit 86 and the second detection circuit 90 have been described as examples configured as hard logic circuits, but some of them are realized by software in the laser radar CPU 70c. It is also possible. Conversely, processing such as obtaining the distance L to the reflecting object from the time difference Δt between the laser light emission time t0 and the peak value generation time tp of the received light signal in the laser radar CPU 70c can also be realized by a hard logic circuit. is there.

  (4) In the above-described embodiment, an example has been described in which light reception signals based on a plurality of adjacently irradiated laser beams are integrated in each scanning line scanned in the X-axis direction. However, the received light signal to be integrated is not limited to the laser light irradiated adjacently in the X-axis direction, but may be the laser light irradiated adjacently in the Y-axis direction. Furthermore, the range of the laser light irradiated adjacently may extend to a plurality of scanning lines of the X axis and the Y axis.

  (5) In the above embodiment, the polygon mirror 73 having a different surface tilt angle is used to perform two-dimensional scanning of the laser beam. However, for example, a galvano mirror that can be scanned in the vehicle width direction is used, and the tilt angle of the mirror surface is used. This can also be realized by using a mechanism capable of changing the above. However, the polygon mirror 73 has an advantage that a two-dimensional scan can be realized only by rotational driving.

  (6) In the above embodiment, the laser radar sensor 5 using laser light is employed. However, radio waves such as millimeter waves, ultrasonic waves, or the like may be used. Moreover, it is not necessary to stick to the scanning method, and any method that can measure the direction other than the distance may be used. For example, when FMCW radar or Doppler radar is used with a millimeter wave, the distance information from the reflected wave (received wave) to the preceding vehicle and the relative speed information of the preceding vehicle can be obtained at one time. The process of calculating the relative speed based on the distance information as in the case of the case becomes unnecessary.

It is a block diagram which shows the structure of the vehicle control apparatus with which this invention was applied. (A) is a block diagram showing a configuration of a laser radar sensor, (b) is a circuit configuration diagram showing a configuration of a first detection circuit in the laser radar sensor, and (c) is a second detection circuit in the laser radar sensor. It is a circuit block diagram which shows the structure of these. It is a perspective view which shows the irradiation area | region of a laser radar sensor. (A) is a wave form diagram for demonstrating the principle of distance detection, (b) is a wave form diagram for demonstrating the calculation method of the peak value in a received light signal. FIG. 10 is a waveform diagram for explaining digital conversion processing on a light reception signal by an A / D conversion circuit in a second detection circuit. It is explanatory drawing for demonstrating the setting method of the number of the light reception signals which should be integrated | accumulated. It is explanatory drawing for demonstrating the movement of the range of the received light signal which should be integrated | accumulated by the integration | stacking range designation | designated circuit of a 2nd detection circuit. (A) is explanatory drawing for demonstrating that the amplification degree of the light reception signal component corresponding to the intensity | strength of reflected light is larger than the amplification degree of a noise signal component, when a some light reception signal is integrated | accumulated. (B) is a wave form diagram for demonstrating the principle of the distance detection to a reflective object based on the integration signal. It is a wave form diagram for demonstrating the linear interpolation process performed in the interpolation circuit of a 2nd detection circuit. It is a block diagram which shows the structure of the laser radar sensor with which the vehicle control apparatus of 2nd Embodiment of this invention is equipped. It is a block diagram which shows the structure of the laser radar sensor with which the vehicle control apparatus of 3rd Embodiment of this invention is equipped. It is a block diagram which shows the structure of the laser radar sensor with which the vehicle control apparatus of 4th Embodiment of this invention is equipped.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vehicle control apparatus, 5 ... Laser radar sensor, 70a ... Light emission part (transmitting means), 70b ... Light receiving part (reception means), 70c ... Laser radar CPU, 71 ... Light emitting lens, 72 ... Scanner, 73 ... Mirror, 74 DESCRIPTION OF SYMBOLS ... Motor drive circuit, 75 ... Semiconductor laser diode, 76 ... Laser diode drive circuit, 81 ... Light receiving lens, 82 ... Light receiving element (light reception signal component output unit), 83 ... Dummy circuit (noise component output unit), 84 ... Selector ( (Selection unit), 85 ... amplifier, 86 ... first detection circuit, 87 ... comparator, 88 ... time measurement circuit, 90 ... second detection circuit, 91 ... A / D conversion circuit, 93 ... storage circuit, 95 ... accumulation range designation Circuit 97... Integration circuit 97 99 background noise calculation circuit (noise component calculation unit) 100 switching circuit 101 subtraction circuit removal unit 03 ... comparator, 105 ... threshold setting circuit, 109 ... interpolation circuit, 111 ... time measuring circuit, 140 ... light emitter (electromagnetic wave output unit), 150 ... switching unit.

Claims (4)

Transmitting means (70a) for irradiating a plurality of transmission waves over a predetermined angular range;
Receiving means (70b) for receiving a reflected wave with respect to the transmitted wave and outputting a received signal corresponding to the intensity of the reflected wave when the reflected wave is received;
Based on the received signal from the receiving means, a noise component calculating unit (99) that calculates a noise component to be superimposed on the received signal, and removing the noise component obtained by the noise component calculating unit from the received signal And a detecting unit (103, 105, 109, 111) for detecting a reflecting object reflecting the transmission wave based on the received signal removed by the removing unit. A vehicle radar device comprising a reflection object detection means,
The receiving means includes
A reception signal output unit (82) that outputs a signal including a reception signal component according to the intensity of the reflected wave when the reflected wave is received;
An electromagnetic wave output unit (140) that outputs an electromagnetic wave that saturates the output of the received signal in the received signal output unit;
The noise component calculation unit is configured to calculate the noise component based on the reception signal when an electromagnetic wave that saturates the reception signal output unit is output in the electromagnetic wave output unit,
The vehicular radar characterized in that the removing unit removes the noise component from the received signal when the electromagnetic wave that saturates the received signal output unit is not output by the electromagnetic wave output unit. apparatus. The transmitting means is a light emitting unit that outputs a light wave as the transmission wave,
The receiving means is a light receiving unit that receives reflected light of the light wave as the reflected wave,
The reception signal output unit includes a light receiving element (82) that generates an output corresponding to the intensity of reflected light of the light wave,
The vehicular radar apparatus according to claim 1, wherein the electromagnetic wave output unit includes a light emitter (140) that saturates the output of the light receiving element. The receiving means determines whether or not a received signal component that is output according to the intensity of the reflected wave when the reflected wave is received is included in the received signal;
When the determination unit determines that the reception signal component is not included in the reception signal, a switch unit (160) that transmits the reception signal at that time to the noise component calculation unit. The vehicular radar apparatus according to claim 1, wherein the vehicular radar apparatus is provided. The noise component calculation unit stores a correlation of reflected light noise corresponding to a scanning angle of the transmission wave transmitted by the transmission unit, and it is determined that the reception signal component is not included in the reception signal. Based on the correlation, the reflected light noise for each scanning angle is obtained from the received signal transmitted at that time and the scanning angle at that time, including a scanning angle different from the scanning angle at that time. The vehicular radar apparatus according to any one of claims 1 to 3.

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