JP4545132B2 - Automotive radar system - Google Patents

Description

  The present invention relates to an in-vehicle radar system that performs adaptive control to a traveling situation in an in-vehicle radar device mounted on, for example, an automobile.

The in-vehicle radar device is a sensor used to monitor the periphery of the vehicle, emits radio waves from the in-vehicle radar device to the periphery of the vehicle, and detects obstacles around the vehicle from the reflected waves. Is. Information that can be detected by such an on-vehicle radar device includes a relative distance to a front obstacle, a relative speed, or a position direction of the obstacle.
Applications of in-vehicle radar equipment include automatic speed control systems that realize auto-cruise control, vehicle collision prevention devices that detect possible collisions with obstacles and alert the driver, and that collision avoidance is impossible There is already known a pre-crash safety system that, when judged, controls to protect a person on the vehicle.

  Conventional on-vehicle radar devices are effective when detecting the relative distance and speed of the vehicle and the obstacle moving in a straight line, but when driving on a curve or when changing the direction of the vehicle. It cannot be denied that the reliability is somewhat inferior due to the occurrence of displacement of obstacles during turning and the reduction of the effective radar viewing angle.

  As a method to compensate for this drawback, the vehicle-mounted radar device uses its own lane based on the turning radius of the vehicle and the relative distance to the obstacle under driving conditions that the vehicle-mounted radar device is not good at, for example, when driving on a curve. There is known a method of correcting a region and calculating and correcting a relative distance from a front obstacle, a width, a relative speed, and an angle direction of the obstacle. (For example, Patent Document 1)

In addition, headlamp control is provided with a dedicated obstacle detection lamp that detects obstacles ahead of the vehicle with an in-vehicle radar device and deflects the optical axis of the headlight based on this detection information to illuminate the direction of the obstacle. The system is known. (For example, Patent Document 2)
Further, there is known a vehicular illumination device that performs appropriate illumination by performing follow-up control on the maximum deflection angle of the lamp based on the vehicle steering angle and the vehicle speed. (For example, Patent Document 3)

Japanese Patent Laid-Open No. 10-54875 JP 2005-67294 A JP 2002-326538 A

In each of the conventional methods, when a sufficient radar viewing angle can be secured, for example, when the vehicle speed is sufficiently slow or the turning radius R is large, it is effective. However, when the vehicle speed is high or the turning radius R is small, the effective radar viewing angle is narrowed and it is difficult to capture an obstacle.
In general, the radar viewing angle is required to cover a wide area, but the control time for mechanically swinging the antenna left and right is limited by the mechanism structure and the driving force of the actuator. Therefore, if the radar viewing angle is to be widened while maintaining the angle measurement performance of the existing radar, there is a problem that the radar scanning time per time increases and the calculation time for the distance and relative speed increases accordingly.

  An object of the present invention is to alleviate a decrease in radar detection performance when a vehicle turns, which is not good for an on-vehicle radar device, for example, while driving on a curve.

An in-vehicle radar system of the present invention includes an antenna that radiates radio waves to an object and receives a reflected wave thereof, a transmission / reception unit that modulates a signal transmitted from the antenna and demodulates a signal received by the antenna, An actuator unit that swings the antenna to the left and right, and the actuator unit is controlled to periodically swing the antenna to determine a radar scanning range, and the object is detected from the received signal demodulated by the transmitter / receiver unit. A radar device having a signal processing unit for detection processing, and a lighting device for deflecting and controlling an irradiation direction (swivel angle) of a headlight based on information related to a traveling state of the own vehicle. Control means for controlling a deflection angle of a radar scanning range of the radar device based on a swivel angle signal from an illumination device is provided, When the swivel angle acquired from the illumination device is a predetermined value or less, the control means sets the deflection angle of the radar scanning range to an initial value or a zero value, and when the swivel angle acquired from the illumination device is a predetermined value or more, The deflection angle of the radar scanning range is controlled to follow in proportion to the swivel angle, the predetermined value is changed according to the vehicle speed, and the deflection angle of the radar scanning range is estimated from the inverse sine function of the turning radius of the own vehicle. This is calculated in proportion to the swivel angle.

  According to the on-vehicle radar system configured as described above, it is possible to appropriately control the deflection of the radar scanning range according to the traveling situation with the existing radar viewing angle. Under the traveling curve, the same effect as widening the radar field of view can be obtained, and the decrease in the tracking performance of the in-vehicle radar device can be reduced.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing the configuration of an in-vehicle radar system according to Embodiment 1 of the present invention.
The on-vehicle radar system according to the present invention includes a radar device 1 mounted on a vehicle and an illumination device 2 of an adaptive lighting system AFS (Adaptive Front-lighting System) mounted on the same vehicle.
The radar apparatus 1 mounted on the vehicle detects a relative distance, a relative speed, or an obstacle direction with respect to an obstacle (object) in front of the vehicle by radiating a radio wave to the object and receiving the reflected wave. This is a device for detecting the possibility of collision. The illumination device 2 of the adaptive illumination system AFS mounted on the vehicle is equipped with headlights that can be controlled to deflect the illumination direction in the left-right direction on the left and right sides of the front part of the vehicle, respectively. This is a technique for improving the visibility of the surroundings of the vehicle to the driver, and a technique specialized for identifying the driving environment.
is there.

The radar apparatus 1 includes an antenna 11, a transmission / reception unit (hereinafter referred to as a transmission / reception unit) 12, an actuator unit 13 that drives the antenna 11, a position detection unit 14 that detects the position of the antenna 11, and a signal processing unit 15. ing.
The antenna 11 is a directional antenna provided in the vicinity of the front grille of the vehicle, for radiating radio waves to the object and receiving reflected waves from the object, and has a preset swing angle. The front of the host vehicle is scanned by mechanically swinging left and right at (scanning angle). The transmission / reception unit 12 includes a transmission unit that modulates a signal transmitted from the antenna 11 and a reception unit that demodulates a signal received by the antenna 11. The actuator unit 13 is for swinging and driving the antenna 11 to the left and right at a fixed cycle, and is constituted by, for example, an electric motor or a magnetic circuit, and is controlled by a control signal from a signal processing unit 15 described later. The position detection unit 14 is configured by, for example, a position sensor or the like provided in either the antenna 11 or the actuator unit 13 and detects the position of the antenna 11. The position detection unit 14 detects the actual driving position of the antenna 11 driven by the actuator unit 13 and performs feedback control so as to match a target driving position of a control signal supplied from a signal processing unit 15 described later. Provided for.

  The signal processing unit 15 is constituted by, for example, a microcomputer, and calculates a radar scanning range by calculating a control signal of a scanning angle that is a deflection angle as a scanning center axis of the antenna 11 and a swing angle from the scanning center axis. By supplying a control signal to the actuator unit 13, the antenna 11 is periodically driven to swing left and right. The signal processing unit 15 receives the radio wave reflected from the front obstacle by the radio wave irradiated from the antenna 11 and calculates the signal delay time or Doppler frequency component from the received signal demodulated by the transmission / reception unit 12. Then, the relative distance, relative speed, and position of the obstacle are detected by FET (Fast Fourier Transform) calculation processing. Further, the signal processing unit 15 controls the timing of radiating radio waves from the antenna 11 and the timing of scanning by periodically swinging the antenna 11. Although not shown, the signal processing unit 15 inputs signals such as the steering angle, yaw rate, and vehicle speed of the vehicle, and determines the radar viewing angle that is the scanning angle of the antenna 11.

  The signal processing unit 15 also receives a swivel angle signal that is the headlight irradiation direction from the illumination device 2 of the adaptive illumination system AF, and controls the deflection angle of the radar scanning range of the radar device 1. 16 is provided. The control means 16 is provided in the signal processing unit 15 in FIG. 1, but may be provided separately from the signal processing unit 15.

  As shown in FIG. 2, the antenna 11 is housed in a housing 11a, and the front surface is covered with a radome 11b. The antenna 11 uses the center axis of the radio wave beam radiated in front of the vehicle as the scanning center axis S, and swings the scanning center axis S to the left and right by the actuator unit 13 to set the radar scanning range. It becomes an area. For example, in FIG. 2, a region formed by swinging from the scanning center axis S to the left and right at a scanning angle of 10 degrees, that is, a swing range θa scanned by the antenna 11 is a radar scanning range. The swing range θa scanned by the antenna 11 is a physical maximum swing range θmax in which the antenna 11 can be swung left and right, that is, a range in which the radio wave beam strikes the housing 11a by swinging the antenna 11 left and right. Is also controlled to swing left and right within a narrow range.

Further, when the center axis of the radio wave beam radiated in the same direction as the host vehicle is traveling straight is coincident with the scanning center axis S, the deflection angle θd of the radar scanning range is an initial value or a zero value. When the vehicle travels along a curve, the deflection angle θd of the radar scanning range is deflected to a predetermined angle other than the initial value or zero value (for example, in FIG. 2, the scanning center axis S is a one-dot chain line). The deflection angle θd of the radar scanning range is determined so that the left and right sides of the radio wave beam radiated from the antenna 11 are in contact with the casing 11a that houses the antenna 11 until the antenna 11 swings (scanning center axis). S) can be deflected.
When the deflection angle θd of the antenna 11 is deflected to the right from the initial value or zero value, the deflection angle θd is positive, and when the antenna 11 deflection angle θd is deflected to the left from the initial value or zero value, The deflection angle θd is negative.
The deflection angle θd for deflecting the scanning center axis S of the radar scanning range of the antenna 11 is controlled based on the irradiation direction (swivel angle) of the illumination device 2 as will be described later.

  Here, the operation of the radar apparatus 1 mounted on the vehicle will be briefly described. The signal processing unit 15 controls the transmission / reception unit 12 to transmit a predetermined radio wave beam from the antenna 11. At the same time, in accordance with this transmission timing, a control signal for the scanning angle of the antenna 11 is supplied to the actuator unit 13, and the antenna 11 is controlled to swing left and right at a predetermined cycle. In this way, the antenna 11 radiates a radio wave beam to an object (obstacle) existing within the radar scanning range which is the oscillation range θa of the antenna, and receives the reflected wave.

  The signal of the reflected wave received by the antenna 11 is demodulated by the transmission / reception unit 12. The signal processing unit 15 detects the relative distance, relative speed, and position of the obstacle present in the scanning angle direction by performing FET arithmetic processing on the reception signal demodulated by the transmission / reception unit 12. Information such as the relative distance to the obstacle, the relative speed, and the detection position detected by the signal processing unit 15 is transmitted through a signal line 6 to a vehicle such as an automatic vehicle speed control system, a vehicle collision prevention device, and a pre-crash safety system. It is sent to the control device 3 and processing corresponding to each device is performed.

The illumination device 2 of the adaptive illumination system AFS includes a headlight 21, an actuator unit 22 that drives the headlight 21, and an AFS-electronic unit (AFS-ECU) 23 that controls the actuator unit 22.
The headlights 21 are respectively provided on the left and right of the front part of the automobile, and the irradiation direction (swivel angle) can be deflected in the left-right direction by tilting driving reflectors provided around the lamp. The actuator unit 22 is composed of, for example, a motor or a bearing, and tilts and drives the reflector of the headlight 21 to control the swivel angle of the headlight 21 in the left-right direction. The AFS-electronic unit 23 calculates the irradiation direction (swivel angle) of the headlight 21 based on the output of the information sensor 4 indicating the running state of the automobile, and drives the actuator unit 22 by a control signal corresponding to the swivel angle. The swivel angle of the headlight 21 is controlled to be deflected in the left-right direction. The swivel angle of the headlight 21 is, as shown in FIG. 3, when the optical axis L of the irradiation light coincides with the straight traveling direction of the host vehicle, the optical axis L is left or right ( In FIG. 3, it means the angle θs deflected by swinging to the right (shown by a one-dot chain line).

Note that feedback control is performed so that the actual drive amount by the actuator unit 22 matches the target drive amount from the AFS-electronic unit 23.
Here, the output of the information sensor 4 indicating the traveling state of the vehicle is, for example, a vehicle-mounted radar device for detecting the steering angle of the steering wheel SW of the vehicle, the speed of the vehicle, the steering angle of the vehicle, and obstacles ahead of the vehicle. 1 is a detection output (information such as a relative distance to an obstacle, a relative speed, and a detection position), and other information indicating a running state of the automobile.

Next, the operation of the illumination device 2 of the adaptive illumination system AFS will be described. The AFS-electronic unit 23 estimates the turning radius R after t seconds on the basis of the steering angle of the steering wheel SW, the speed of the automobile, and the steering angle of the steering wheel from the information sensor 4 that indicates the traveling state, and sets the turning radius R to the turning radius R. Based on this, a deflection amount (swivel angle θs) for deflecting the irradiation direction of the headlight 21 is calculated. The actuator unit 22 is driven based on the swivel angle θs, and the headlight 21 is deflection-controlled in the left or right direction.
For example, the characteristic of the turning radius R-swivel angle θs by AFS control at a certain speed is expressed as shown in FIG. 4, and the swivel angle θs increases as the turning radius R decreases. In this characteristic, the curve curve shifts to the left as the speed of the vehicle decreases.

The AFS-electronic unit 23 may determine the swivel angle θs in consideration of the output of the in-vehicle radar device 1 and control the irradiation direction of the headlight 21 to the front obstacle.
As the control means of the headlight 21 by the illumination device 2 of the adaptive illumination system AFS, there are a method of moving the whole or a part of the low beam and a method of adding a fixed or movable dedicated light source, whichever is used. May be.
Further, there are a single swing method in which the headlights 21 mounted on the left and right of the front part of the vehicle are swiveled according to the driving situation, and a full swing method in which both are swiveled simultaneously. May be used.

  The control means 16 of the on-vehicle radar device 1 and the AFS-electronic unit 23 of the illumination device 2 of the adaptive illumination system AFS are connected by a signal line 5, and the control means 16 of the radar device 1 is adapted to the adaptive illumination system AFS. A signal corresponding to the swivel angle θs is obtained from the AFS-electronic unit 23 of the illumination device 2. When the swivel angle θs signal is input to the control means 16 of the radar apparatus 1, the control means 16 calculates the deflection angle θd of the radar scanning range of the radar apparatus 1 based on the swivel angle θs signal, and this deflection angle. The actuator unit 13 is controlled based on the signal θd.

Hereinafter, a method for controlling the deflection angle θd of the radar scanning range of the radar apparatus 1 based on the signal of the swivel angle θs by the control means 16 will be described.
FIG. 5 is a schematic view of the vehicle traveling on a curve. 7 shows the radar viewing angle θ and the maximum detection distance r of the radar apparatus 1 when the host vehicle 7 travels on a road having a turning radius R centered on the O point 8.

FIG. 6 is a flowchart showing the flow of processing in Embodiment 1 of the present invention.
In step 61, the control means 16 of the radar apparatus 1 acquires a signal corresponding to the swivel angle θs from the AFS-electronic unit 23 of the illumination apparatus 2 of the adaptive illumination system AFS via the signal line 5 or the like.
In step 62, the control means 16 determines whether the swivel angle θs is equal to or greater than a predetermined value (α angle). The predetermined value α of the swivel angle θs is determined from, for example, the maximum deflection angle of the radar apparatus 1, the maximum detection distance r of the radar apparatus 1 at a certain speed, and the radar viewing angle θ.

  In step 62, if the swivel angle θs acquired by the control means 16 is equal to or less than the α angle, the process proceeds to step 63, and the deflection angle θd of the radar scanning range is set to an initial value or zero. Therefore, the swing range of the antenna 11 scans the front of the host vehicle by mechanically swinging the antenna 11 to the left and right with a preset swing angle around the initially installed position.

  In step 62, when the swivel angle θs acquired by the control means 16 is not less than the α angle, the process proceeds to step 64. In step 64, the control means 16 calculates a deflection angle θd for tilting the radar scanning range scanned by the radar apparatus 1 based on the swivel angle θs. For example, as shown in FIG. 7, with respect to the swivel angle estimated from the inverse sine function of the turning radius R of the vehicle, the deflection angle θd of the radar scanning range is calculated in proportion to the swivel angle θs with a certain swivel angle as a threshold value. .

  In step 65, based on the calculated deflection angle θd of the radar scanning range, the actuator 13 is controlled to swing so that the output of the position detector 14 is offset by the deflection angle with respect to the swing center of the antenna 11. Alternatively, the radar scanning range is deflected by offsetting the drive amount of the actuator unit 13 based on the deflection angle θd. At this time, the direction of the deflection angle θd of the radar scanning range is naturally a direction that follows the swivel angle direction of the headlight 21 of the illumination device 2.

Step 66 is a process of driving the actuator unit 13 by increasing / decreasing a predetermined minute control amount to shift to a target deflection angle.
When the drive amount by the actuator unit 13 matches the target deflection angle, the process returns to step 61. In this way, Step 61 to Step 66 are repeatedly performed.

  In steps 65 and 66, the detection position or detection direction of the obstacle in front of the vehicle detected by the in-vehicle radar device 1 according to the increase or decrease of the control amount by the actuator unit 13 is processed by software (SW). An offset correction may be performed based on the deflection angle θd of the radar scanning range to prevent the positional deviation detected by the radar apparatus 1.

With the above processing, the maximum detection distance r as shown in FIG. 8 is realized. FIG. 8 is a characteristic of the turning radius R−the maximum detection distance r when the radar viewing angle θ is different while traveling at a constant speed v.
In FIG. 8, a thin solid line 81 is an existing radar viewing angle, a dashed line 82 is a viewing angle wider than the existing radar viewing angle by the deflection angle θd, and a thick solid line 83 follows the swivel angle θs by the processing of the present invention. This shows the radar viewing angle under deflection control.
If the vehicle speed is faster than v, the point point a at which the control characteristic changes moves to the upper right along the dashed line 82, and if the vehicle speed is slower than v, the point at the point a moves to the lower left along the dashed line 82. Moving.

  As can be seen from FIG. 8, when the turning radius R is small, the radar viewing angle θ (see FIG. 5) can be reduced, and the field of view wider than the existing radar viewing angle by the deflection angle θd. A maximum detection distance r equivalent to a corner can be obtained. When the turning radius R is large, the swivel angle θs decreases, so the deflection angle θd of the radar scanning range decreases, and the deflection angle θd of the radar scanning range also decreases according to the swivel angle θs. Thereby, the radar visual field according to the turning radius R can be secured. Thus, even when no obstacle is detected in front of the vehicle under a curve, if the swivel angle θs is equal to or greater than the α angle, the driving situation acts to reduce the decrease in the maximum detection distance r of the radar device 1. Adaptive control can be performed according to

According to the on-vehicle radar system configured as described above, it is possible to appropriately deflect and control the radar scanning range in accordance with the traveling state with the existing radar viewing angle. In particular, under the curve traveling that the in-vehicle radar device 1 is not good at, it is possible to obtain the same effect as widening the radar field of view, and to reduce the follow-up performance of the radar device 1.
Information on the relative distance to the obstacle ahead, the relative speed, or the position direction of the obstacle detected by the radar device 1 that is adaptively controlled according to the driving situation is the vehicle's automatic speed control system, pre-crash safety system, etc. Used in the control device 3.

  Also, in the AFS of the type in which the irradiation direction (swivel angle) of the headlight 21 in the illumination device 2 of the adaptive illumination system AFS is deflected based on the output of the in-vehicle radar device 1 that detects the front obstacle part, Under curve traveling, feedback control is performed between the illumination device 2 of the adaptive illumination system AFS and the in-vehicle radar device 1, so that the tracking performance of the radar device is improved.

The block diagram showing the structure of Embodiment 1 of this invention. The figure showing the structure and deflection | deviation state of an antenna used for Embodiment 1 of this invention. The figure showing the irradiation state of the headlight used for this invention. The turning-radius R-swivel angle characteristic view of the illuminating device used for this invention. Schematic when the vehicle travels on a curve. The flowchart which shows the flow of the process in this invention. The swivel angle used for this invention-the deflection angle characteristic figure of a radar scanning range. The characteristic diagram of turning radius R-maximum detection distance r when radar viewing angles are different.

Explanation of symbols

1: Vehicle-mounted radar device 2: AFS lighting device 3: Vehicle control device 4: Information sensor indicating vehicle running condition 5: Signal line 6: Signal line 7: Own vehicle 8: Curve turning center Point O
R: turning radius r: maximum detection distance 11: antenna, 11a: antenna housing 11b: antenna radome 12: transmission / reception unit 13: actuator unit of Radar apparatus, 14: position detection unit 15: signal processing unit, 16: control means 21: Headlight, 22: Actuator part of illumination device 23: AFS-ECU, θ: Radar viewing angle θd: Deflection angle of radar scanning range θs: Swivel angle

Claims (4)

An antenna that radiates a radio wave to an object and receives a reflected wave thereof, a transmission / reception unit that modulates a signal transmitted from the antenna and demodulates a signal received by the antenna, and swings the antenna left and right An actuator unit, and a signal processing unit that controls the actuator unit to periodically swing the antenna to determine a radar scanning range and detect and process the object from the reception signal demodulated by the transmission / reception unit The vehicle includes a radar device and a lighting device that controls deflection of a headlight irradiation direction (swivel angle) based on information related to the traveling state of the vehicle, and the radar device uses a swivel angle signal from the lighting device. Control means for controlling the deflection angle of the radar scanning range of the radar apparatus based on the control means, and the control means is obtained from the illumination device. When the swivel angle is less than a predetermined value, the deflection angle of the radar scanning range is set to an initial value or zero value. When the swivel angle acquired from the illuminating device is greater than the predetermined value, the deflection angle of the radar scanning range is set to the swivel angle. The tracking control is proportionally performed, the predetermined value is changed according to the vehicle speed, and the deflection angle of the radar scanning range is calculated in proportion to the swivel angle estimated from the inverse sine function of the turning radius of the vehicle. In-vehicle radar system.   The in-vehicle control according to claim 1, wherein the swing range of the antenna, which is a radar scanning range of the radar device, is controlled to swing within a range narrower than a physical maximum swing range in which the antenna can be swung left and right. Radar system.   The control means can deflect the oscillation center of the antenna until just before either one of the left and right sides of the radio wave beam radiated from the antenna hits the casing housing the antenna. The on-vehicle radar system according to 2.   When the swivel angle acquired from the illumination device is greater than or equal to a predetermined value, the control means performs offset correction on the detection direction or detection position of the object detected by the radar device based on the deflection angle of the radar scanning range. Item 2. The in-vehicle radar system according to Item 1.

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