JP5167866B2 - Vehicle speed control device - Google Patents

Description

  The present invention relates to a technical field of a preceding vehicle detection device and a vehicle speed control device using the same.

  Currently, the leading vehicle detection devices for vehicle speed control such as the ACC system (Adaptive Cruise Control System) and the pre-crash brake system include scanning radars such as laser radars using infrared rays and millimeter wave radars using millimeter-wave radio waves. Radar devices are widely used. Here, the ACC system performs vehicle speed control by following the preceding vehicle traveling in front of the host vehicle, and the pre-crash brake system estimates the possibility of collision with a front object, and collision is inevitable. In this case, the automatic brake is operated.

In Patent Document 1, in the ACC system, a back surface angle, which is a traveling angle of a preceding vehicle captured by a radar device, with respect to the host vehicle is calculated, thereby estimating a front road shape and speed control according to the estimated road shape. Techniques for performing are disclosed.
JP 2000-131436 A

  However, in the above prior art, since it is assumed that the preceding vehicle is continuously traveling on the own vehicle traveling lane, in the situation where the preceding vehicle leaves the own vehicle traveling lane, the straight line In spite of the road, there is a problem that an incorrect road shape indicating that the road is a curved road is output from the rear angle of the preceding vehicle, and smoothing of the vehicle speed control is hindered.

  On the other hand, a method of performing lane detection with a front monitoring camera is also known, but the front monitoring camera has a shorter range than a radar device, and therefore the lane determination possible distance is 30 to 40 m ahead of the host vehicle. Therefore, when the distance to the preceding vehicle becomes longer during traveling on an expressway that mainly operates the ACC system, it is not possible to detect a lane change of the preceding vehicle.

The present invention has been made in view of the problems the prior art facing, and an object is to provide a preceding vehicle car speed control device that can detect a lane change.

To achieve the above object, in a first shot bright, even during straight of the vehicle, if the rear angle within a target inter-vehicle time of the follow-up run control is reduced after the increase, the preceding vehicle has changed lanes and A lane change determining means for determining is provided, and when it is determined that the preceding vehicle has changed lane during follow-up traveling, the vehicle shifts to constant speed traveling.
According to the second aspect of the present invention, the vehicle further comprises lane change determining means for determining that the preceding vehicle has changed lanes when the back angle decreases after increasing in a straight line of the host vehicle, and the vehicle is traveling straight ahead, and the following traveling control is performed. If no change that decreases after the back angle increases after the target inter-vehicle time elapses, the following traveling control is maintained.

  When the preceding vehicle changes lanes, its rear angle decreases after increasing. When the host vehicle is traveling straight ahead, the road shape ahead of the host vehicle is likely to be a straight line. That is, in the present invention, it is possible to detect a lane change of the preceding vehicle by looking at a change in the rear angle of the preceding vehicle while the host vehicle is traveling straight ahead.

  Hereinafter, the best mode for carrying out a preceding vehicle detection device and a vehicle speed control device using the same according to the present invention will be described based on Examples 1 and 2.

[Example 1]
FIG. 1 is a control block diagram illustrating an ACC system according to the first embodiment. The ACC system according to the first embodiment includes a preceding vehicle detection device 100, a vehicle control CPU unit (vehicle speed control means) 400, a vehicle sensor 500, have.
The preceding vehicle detection device 100 includes a radar head unit 200 and an object identification unit 300. The object identification unit 300 is composed of a CPU, a ROM, a RAM, and the like, and has a grouping processing unit 301, a preceding vehicle and a traveling path determination unit 302, a preceding vehicle lateral position and vehicle body inclination calculation storage unit 303, and the functions performed internally. ,have.

FIG. 2 is a configuration diagram of the radar head unit 200 according to the first embodiment. The radar head unit 200 includes a signal transmission unit 210, a signal reception unit 220, and a radar drive processing unit 230.
The signal transmission unit 210 includes a light emitting element 211 such as a light emitting diode, a light emission control unit 212 that controls light emission of the light emitting element 211, a condensing lens 213 that collects output light of the light emitting element 211 and outputs laser light. A reflection mirror 214 that reflects the laser light, and a reflection mirror angle changing unit 215 that changes the angle of the reflection mirror 214 in order to change the transmission direction of the laser light.

  The signal receiving unit 220 includes a light receiving lens 222, a light receiving element 221, and an IF amplifier 223. The radar drive processing unit 230 observes a reception signal from a transmission timing, a transmission trigger generation unit 231 that generates a light emission trigger signal at each laser light emission timing, a transmission azimuth setting unit 232 that specifies an angle of the reflection mirror 214, and A distance detection unit 233 that calculates a distance based on the time difference until.

Here, the distance measurement operation of the radar head unit 200 will be described.
Upon receiving the vehicle-side radar operation command, the transmission trigger generation unit 231 outputs a light emission command that is a rectangular wave transmission timing signal to the light emission control unit 212. The light emission control unit 212 causes the light emitting element 211 to emit light at the rise (or fall) timing of the transmission timing signal. The light emitting element 211 emits light with an extremely short time width (for example, 30 nanoseconds). The reflection mirror 214 emits the pulsed light collected by the condenser lens 213 forward.

  In the distance detection unit 233, based on the time difference (Δt in FIG. 3) from the time when the pulse light is transmitted to the time when the reflected light signal reflected by the target in front of the light receiving element 221 of the signal reception unit 220 is received. The distance to the front target is calculated and output to the object identification unit 300 together with the transmission direction information calculated from the reflection mirror angle.

  At this time, the distance measurement is continuously performed by changing the angle of the reflection mirror 214 by the transmission azimuth setting unit 232 so as to perform the distance measurement of a necessary range within a predetermined time (for example, 100 milliseconds), The distance information for each transmission direction is output to the object identification unit 300.

  The object identification unit 300 performs a process of grouping reflection point groups that are the same object based on the distance information and the direction information output from the radar head unit 200. As a condition for grouping, close reflection point groups having the same moving direction are grouped together and grouped with one object. An object that exists in the traveling direction of the host vehicle from the grouped object group, has a low relative speed with the host vehicle, and has a characteristic characteristic of the vehicle from the characteristic reflection by the reflector and the detected object width is determined as the preceding vehicle. The distance and direction to the vehicle are output to the vehicle control CPU unit 400.

Returning to FIG. 1, the vehicle control CPU 400 performs follow-up running control that maintains the time between the preceding vehicle and the target vehicle based on the detected distance information to the preceding vehicle and direction information. The execution of the follow-up running control is referred to as “preceding vehicle follow-up mode”. Here, the target inter-vehicle time is a time obtained by dividing the target inter-vehicle distance between the preceding vehicle and the host vehicle by the vehicle speed of the host vehicle. The target inter-vehicle distance is set to a longer distance as the vehicle speed of the host vehicle is higher.
On the other hand, when no preceding vehicle is detected, vehicle control CPU 400 performs constant speed running control that maintains the host vehicle speed at the target vehicle speed. The execution of this constant speed running control is referred to as “constant speed running mode”. Here, the target vehicle speed is set to a value manually set by the driver, for example.

  The vehicle sensor 500 includes a lateral G sensor 501, a vehicle speed sensor 502, and an ACC switch 503. The lateral G sensor 501 detects the lateral acceleration (lateral G) of the host vehicle and transmits lateral G information to the preceding vehicle and the travel path determination unit 302. The vehicle speed sensor 502 detects the vehicle speed (vehicle speed) of the host vehicle and outputs vehicle speed information to the grouping processing unit 301. The ACC switch 503 is a switch for the driver to select whether the ACC system is activated or deactivated, and transmits a switch signal to the radar head unit 200.

Next, distance measurement operation timing will be described.
FIG. 3 shows a trigger signal transmitted from the transmission trigger generation unit 231 in order to transmit pulsed light from the light emitting element 211, a light emission pulse signal generated by the light emission control unit 212, and pulse light transmitted from the light emitting element 211. 4 is a time chart showing the relationship between the light receiving element and the light receiving signal when the light receiving element 221 receives the reflected light from the front.

  When a rectangular wave transmission trigger signal (FIG. 3 (a)) is sent from the transmission trigger generation unit 231 to the light emission control unit 212 to transmit pulsed light, the light emission control unit 212 is synchronized with the rising edge of the trigger signal. Then, a light emission pulse having a pulse width τ (for example, 30 nanoseconds) is generated (FIG. 3B), and a light pulse transmission signal (FIG. 3C) is forwarded from the light emitting element 211 via the reflection mirror 214. Sent to.

The transmitted pulsed light is reflected by a reflecting object in front of the host vehicle, and is received as a reflected signal (FIG. 3D) by the light receiving element 221 of the signal receiving unit 220. Assuming that the time from when the pulsed light is sent to when the reflected light is received is Δt and the speed of light is C, the distance D from the preceding vehicle detection device 100 to the reflecting object is calculated by the following equation (1). .
D = C × Δt / 2 (1)
Here, in calculating the actual distance, an error in the measurement distance caused by a circuit delay or the like is taken into account, and the error is corrected to calculate the distance to the target.

  The light receiving element 221 of the signal receiving unit 220 senses continuously incident light (stationary light) such as illumination and solar radiation. Therefore, by inserting a capacitor with an appropriate capacity in series in the signal transmission line immediately after the light receiving element 221, it is possible to detect the high-frequency signal component of the ranging pulse light while removing the DC component such as stationary light. Can do.

[Leading vehicle follow-up travel control processing]
FIG. 4 is a flowchart showing the flow of the preceding vehicle follow-up travel control process provided as a program in the ACC system of the first embodiment. Each step will be described below. This control process is repeatedly executed at a predetermined calculation period when the ACC system is operating (when the ACC switch 503 is ON) and the preceding vehicle following mode is being executed.

  In step S1, the radar head unit 200 performs a ranging operation by radar, transmits distance information and azimuth information to the object identification unit 300, and proceeds to step S2.

  In step S2, the grouping processing unit 301 performs grouping processing based on the direction information and distance information detected by the radar head unit 200, and the vehicle determined as the traveling vehicle existing in the traveling direction of the host vehicle is set as the preceding vehicle. Extract and move to step S3.

  In step S3, in the preceding vehicle and the travel path determination unit 302, based on the lateral G information from the lateral G sensor 501, direction information and distance information of the preceding vehicle, the host vehicle is in a straight traveling state, and the lateral position of the preceding vehicle It is determined whether the amount of deviation is equal to or less than a predetermined value. If YES, the process proceeds to step S4. If NO, the process proceeds to step S5. Here, the amount of lateral displacement is the amount of displacement in the vehicle width direction of the preceding vehicle with respect to the host vehicle.

  In step S4, the preceding vehicle and the traveling road determination unit (curved road determining means) 302 determine that the preceding vehicle is traveling on the curved road, and the vehicle control CPU unit 400 continues the “preceding vehicle following mode”. And move to return.

  In step S5, the lateral position deviation amount and the rear angle (body inclination) of the preceding vehicle are calculated and stored in the preceding vehicle lateral position and body inclination calculation storage unit (rear angle detection means, lateral position deviation amount detection means) 303. And move to step S6. Here, the back angle is a traveling angle of the preceding vehicle with respect to the host vehicle.

  In step S6, based on the lateral G information from the lateral G sensor 501, the preceding vehicle and the travel path determination unit (straight-running state detection means) 302 determine whether or not the lateral G of the host vehicle is equal to or smaller than a predetermined value. It is determined whether the vehicle is traveling on a straight road. If YES, the process proceeds to step S7. If NO, the process proceeds to step S4. Here, instead of the lateral G information, whether or not the host vehicle is traveling on a straight road is determined based on steering angle information from a steering angle sensor (not shown) that detects the steering angle of the steering wheel. Good.

  In step S7, the preceding vehicle and travel path determination unit 302 determines whether or not the target inter-vehicle time for follow-up travel control has elapsed since the memory storage start time in step S5. If YES, the process moves to step S8, and if NO, the process moves to step S4.

  In step S8, whether or not the preceding vehicle and the travel path determination unit 302 showed a change in which the lateral angle of the preceding vehicle is a displacement corresponding to the lane width and the back angle has decreased after the increase in the target inter-vehicle time. Determine. If YES, the process proceeds to step S9. If NO, the process proceeds to step S4.

  In step S9, the preceding vehicle and travel path determination unit (lane change determination means) 302 determines that the preceding vehicle has changed lanes (preceding vehicle departure), and the vehicle control CPU unit 400 determines “constant speed at the set vehicle speed. Shift to “travel mode” and return.

Next, the operation will be described.
[Lane change judgment of the preceding vehicle]
FIG. 5 shows a state in which the preceding vehicle 602 has reached a curved road when the own vehicle 601 is performing follow-up traveling control on the preceding vehicle 602 existing in the detection area 610 of the radar device. At this time, as shown in FIG. 6, the position of the reflection reflector of the preceding vehicle 602 (two reflector reflection points 603) is observed by the radar device. The distance and direction of the preceding vehicle 602 are calculated from the coordinates of the center positions of the two reflector reflection points 603.

  In the first embodiment, in this situation, in addition to the lateral displacement amount and distance of the center position of the two reflector reflection points 603, the inclination of the line connecting the two reflector reflection points 603 is calculated, and the preceding vehicle 602 Record as back angle.

When the preceding vehicle 602 travels on a curved road as shown in FIG. 7 and its position changes from 602a to 602b to 602c, the lateral displacement amount and the temporal change in the back angle show a uniform increase (see FIG. 7). 8).
On the other hand, when the preceding vehicle 602 as shown in FIG. 9 changes the lane to the adjacent lane and transits from 602d → 602e → 602f, the lateral displacement amount and the time change of the rear angle up to the time t1 are shown in FIG. However, after time t1, the change in the lateral displacement amount decreases, and the back surface angle decreases (FIG. 10).

  Here, in the prior art, it is a straight road because the road shape ahead is estimated on the basis of the back angle of the preceding vehicle on the assumption that the preceding vehicle is continuously traveling on the own vehicle traveling lane. Nevertheless, the wrong road shape was output as a curved road from the back angle of the preceding vehicle. For this reason, smooth vehicle speed control could not be continued by performing unnecessary deceleration control.

  On the other hand, in the first embodiment, the preceding vehicle lateral position and the lateral position deviation amount and the rear angle stored in the preceding vehicle lateral position and vehicle body tilt calculation storage unit 303 in the preceding vehicle and the travel path determination unit 302 of the object identifying unit 300 are compared. 10 is a change as shown in FIG. 10, it can be determined that the preceding vehicle 602 has changed lanes.

  That is, in the flowchart of FIG. 4, the process proceeds from step S1, step S2, step S3, step S5, step S6, step S7, step S8, and step S9. In step S9, the preceding vehicle and the travel path determination unit 302 It is determined that the vehicle has changed lanes, and the vehicle control CPU 400 shifts from the “preceding vehicle following mode” to the “constant speed running mode”.

  This makes it possible to stably shift to the "Constant-speed running mode" at the target vehicle speed when the preceding vehicle is not present or the "preceding vehicle following mode" by changing the preceding vehicle without continuing the erroneous following-running control. can do. Further, when it is impossible to detect the lane change of the preceding vehicle, it is necessary to wait for the vehicle speed control before the state becomes stable. However, in the first embodiment, the waiting time can be shortened, and the preceding vehicle follow-up response is achieved. High cruise control can be realized.

  On the other hand, in the preceding vehicle and the travel route determination unit 302, the temporal displacement of the preceding vehicle stored in the preceding vehicle lateral position and vehicle body tilt calculation storage unit 303 and the temporal change in the rear angle are as shown in FIG. If it is a change, it can be determined that there is a curved road ahead of the host vehicle.

  That is, in the flowchart of FIG. 4, the process proceeds from step S1 → step S2 → step S3 → step S4 → step S5 → step S6 → step S7 → step S8 → step S4. In FIG. 5, it is determined that there is a curved road ahead, and the vehicle control CPU unit 400 continues the “preceding vehicle follow-up mode” corresponding to the curved road. Thereby, the curved road ahead of the own vehicle can be detected from the change in the rear angle of the preceding vehicle, and for example, vehicle speed control suitable for the curved road such as deceleration according to the radius of curvature can be realized.

Next, the effect will be described.
The preceding vehicle detection apparatus 100 and the ACC system according to the first embodiment have the following effects.

  (1) The preceding vehicle detection device 100 detects the preceding vehicle lateral position and vehicle body inclination calculation storage unit 303 that detects the back angle, which is the traveling angle of the preceding vehicle with respect to the own vehicle, and detects the straight traveling state of the own vehicle. When the back angle decreases after increasing while traveling straight ahead, the preceding vehicle includes a preceding vehicle and a traveling path determination unit 302 that determines that the lane has been changed. Thereby, the lane change of the preceding vehicle can be detected.

  (2) The preceding vehicle detection device 100 includes a lateral preceding vehicle lateral position and vehicle body inclination calculation storage unit 303 that detects a lateral positional deviation amount that is a positional deviation amount of the preceding vehicle with respect to the host vehicle in the vehicle width direction, If the back angle and lateral displacement continue to increase from when at least one of the displacement starts to increase until the host vehicle is no longer going straight, it is determined that the preceding vehicle is traveling on a curved road A preceding vehicle and a travel path determination unit 302. Thereby, it can be detected that there is a curved road ahead of the host vehicle.

  (3) Since the preceding vehicle and the travel path determination unit 302 detects the straight traveling state based on the steering angle, the straight traveling state can be detected with high accuracy.

  (4) Since the preceding vehicle and the traveling path determination unit 302 detect the straight traveling state based on the lateral G that is the vehicle behavior of the host vehicle, the straight traveling state can be detected with high accuracy.

  (5) It is provided with a scanning radar head unit 200 that detects position information of a target from a reflected wave of an electromagnetic wave emitted in front of the host vehicle, and the preceding vehicle lateral position and vehicle body tilt calculation storage unit 303 is provided from the radar head unit 200. The rear angle of the preceding vehicle is calculated based on the information. More specifically, in the first embodiment, a laser radar that transmits and receives infrared light while scanning in the lateral direction is used as the radar head unit 200. In the preceding vehicle lateral position and vehicle body inclination calculation storage unit 303, a pair of the preceding vehicle has. The back angle of the preceding vehicle is calculated from the distance information and the direction information of the reflective reflector. As a result, the back angle of the preceding vehicle can be detected stably even when traveling on a highway where the distance between the preceding vehicle and the preceding vehicle is longer than when traveling in an urban area.

  (6) If the vehicle speed control CPU 400 determines that the preceding vehicle has changed lanes during execution of the “following vehicle follow-up mode”, the vehicle speed control CPU unit 400 shifts to the “constant speed running mode”. Without continuing the control, it is possible to stably shift to the “constant speed traveling mode” at the target vehicle speed when the preceding vehicle is absent, or the “preceding vehicle following mode” by changing the preceding vehicle.

  (7) If the vehicle speed control CPU unit 400 determines that the preceding vehicle is traveling on a curved road during execution of the "preceding vehicle following mode", the vehicle speed control CPU unit 400 continues the following traveling control according to the road surface shape of the curved road. Therefore, vehicle speed control suitable for curved roads can be realized.

  (8) The preceding vehicle detection device 100 determines that the preceding vehicle has changed lanes when the host vehicle is traveling straight and the rear angle decreases after increasing within the target inter-vehicle time for follow-up travel control. Here, if the determination time for lane change or curved road determination is shortened, the determination accuracy deteriorates. Conversely, if the determination time is lengthened, the standby time is lengthened, and if there is a curved road ahead, control will not be in time. In contrast, in the first embodiment, since the determination time is the target inter-vehicle time, both determination accuracy and control responsiveness can be achieved.

[Example 2]
The second embodiment is an example in which millimeter wave band or microwave band radio waves are used as a radar apparatus.
FIG. 11 is a control block diagram illustrating the ACC system according to the second embodiment. In addition, although illustration is abbreviate | omitted about the vehicle sensor 500, since it is the same as that of Example 1 shown in FIG. 1, description is abbreviate | omitted.

  The preceding vehicle detection apparatus 101 according to the second embodiment includes a radar head unit 700 including radar units 240a and 240b and radar signal processing units 250a and 250b, an object identification unit 800, and a vehicle control CPU unit 400. Yes.

  The radar units 240a and 240b respectively transmit transmission signals 210a and 210b that transmit electromagnetic wave transmission signals 1 and 2 to the front space of the vehicle, and reception signals 1, 2, 3, and 4 that are electromagnetic waves reflected by objects ahead. Two receiving means 220a and 220b for receiving. The radar units 240a and 240b are FM-CW (Frequency Modulated-Continuous Wave Method) radar heads using a transmission signal frequency-modulated with a triangular wave (or a sawtooth wave or the like).

  As a distance measurement method, using a transmission signal that is frequency-modulated with a triangular wave, frequency increase modulation and frequency decrease modulation are performed according to the timekeeping time, the frequency difference between the transmission signal and the reception signal at the time of frequency increase modulation, and the frequency The distance is calculated from the average value of the frequency difference between the transmission signal and the reception signal during the downward modulation. Further, the relative speed is measured from the difference value.

  As shown in FIG. 12, the radar units 240a and 240b are arranged at predetermined intervals in the vehicle width direction with respect to the vehicle, and have reflection objects (moving objects V0) in the observation region set so as to overlap each other in front of the vehicle. Car) Send transmission signal to 602.

  Returning to FIG. 11, the transmission means 210a of the radar unit 240a includes a voltage controlled oscillator (VCO) 216a, a power distributor 217a, and a transmission antenna 218a. The VCO 216a generates a transmission signal that is frequency-modulated in accordance with the triangular wave signal (modulated signal 1) transmitted from the triangular wave generation unit 251a of the radar signal processing unit 250a. The power distributor 217a distributes the transmission signal generated by the VCO 216a into two signals at a predetermined power ratio, one is transmitted from the transmission antenna 218a as the transmission signal 1, and the other is a mixer of the two receiving means 220a and 220b. The local signal is input to the circuits 225a and 225b. The transmission antenna 218a transmits the transmission signal 1 to the front space.

  The two receiving means 220a and 220b of the radar unit 240a have receiving antennas 224a and 224b, mixer circuits 225a and 225b, and amplifier circuits 223a and 223b, respectively. The reception antennas 224a and 224b receive the reception signals 1 and 2 (reflected signals) in which the transmission signal transmitted from the transmission antenna 218a is reflected by a front object and returned. The mixer circuits 225a and 225b mix a part of the transmission signal 1 branched by the power distributor 217a with the reception signals 1 and 2, and an IF (Intermediate Frequency) signal 1 having a difference frequency between the transmission signal frequency and the reception signal frequency. , 2 is generated. The amplification circuits 223a and 223b amplify the IF signals 1 and 2 generated by the mixer circuits 225a and 225b, and output the amplified IF signals to the FFT (Fast Fourier Transform) processing units 252a and 252b of the radar signal processing unit 250a.

  FIG. 13 shows an example of transmission / reception signals in the FM-CW radar unit 240a. The horizontal axis of FIGS. 13A to 13D is time t, the vertical axis of FIG. 13A is the signal intensity, and the vertical axis of FIGS. 13B to 13D is the frequency f. First, the transmission signal is frequency-modulated as shown in FIG. 13B in accordance with the triangular wave modulation signal in FIG. 13A (output from the triangular wave generator 251a in FIG. 13). As shown in FIG. 13C, the frequency of the reflected signal (received signal) from the object in front is observed with a time delay by the amount of spatial propagation as compared with the dotted transmission signal. The frequency of the IF signal output from the mixer circuits 225a and 225b in FIG. 11 shows different frequencies f1 and f2 in the frequency rising section and the frequency falling section of the triangular wave, as shown in FIG. 13 (d). Since the average value of these two frequencies f1 and f2 is proportional to the spatial propagation delay time, the distance to the object can be calculated. Further, since the frequency difference Δf (= f2−f1) is proportional to the Doppler frequency, the relative velocity of the object can be calculated.

  Returning to FIG. 11, when the radar unit 240a has an azimuth detection function, a mechanical scanning system that mechanically scans the transmission / reception antenna in a one-dimensional manner and two receiving systems are provided, and the intensity difference between reflected signals received by each of them is determined. There are a monopulse method for calculating the azimuth and a phase difference method for calculating the azimuth from the phase difference between two reflected signals. In the second embodiment, a method using a monopulse method will be described assuming that the test object is a reflective object.

  The antenna gain of the transmission antenna 218a of the transmission means 210a of the radar unit 240a is set to half of the antenna gain of the reception antennas 224a and 224b of the reception means 220a and 220b, and the reception azimuth is such that it overlaps at the half-value angle of the reception antennas 224a and 224b Are different. As an example, as shown in FIG. 14, when the half width of the receiving antennas 224a and 224b is 30 degrees, the receiving sensitivity directions of the receiving antennas 224a and 224b are +15 degrees and -15 degrees, respectively, and the transmitting antenna 218a Is a half-width of 60 degrees and a transmission azimuth of 0 degrees. Note that the vertical axis in FIG. 14 is the azimuth of the reflecting object with respect to the receiving antennas 224a and 224b (here, an angle formed along a direction parallel to the road surface with respect to the forward direction of the vehicle) θ (deg).

The transmission signal 1 transmitted from the transmission means 210a in FIG. 11 is reflected from the front reflecting object and received by the reception means 220a and 220b. Here, if the reflected signals observed at the receiving antennas 224a and 224b are the received signals 1 and 2, the signal strength of the received signal 1 is A1, and the signal strength of the received signal 2 is A2, the signal strengths A1 and A2 (sensitivity) are It is represented by the curves R + and R- in FIG. Further, a standardized difference ΔA of signal intensity is calculated from the following equation (2), and a standardized curve RA (= (R + −R −) / (R ++) indicating the sensitivity difference / sensitivity sum in FIG. 14 is calculated. By comparing with R-)), the azimuth θ of the reflecting object can be obtained.
ΔA = (A1-A2) / (A1 + A2) (2)

  11 also outputs the transmission signal 2 from the transmission means 210b, receives the reception signals 3 and 4 by the reception means 220c and 220d, and processes these reception signals 3 and 4, similarly to the radar section 240a. The IF signals 3 and 4 obtained in this way are output to the FFT processing units 252c and 252d of the radar signal processing unit 250b.

  The radar signal processing unit 250a includes a triangular wave generation unit 251a, an FFT processing unit 252a and 252b that performs frequency analysis of the IF signals 1 and 2 supplied from the radar unit 240a, a frequency average value and a frequency difference between the IF signals 1 and 2. And an object information detection unit 253a that calculates a distance to the reflecting object, a relative speed, and an azimuth from the normalized intensity of the IF signals 1 and 2 (= intensity difference / intensity sum).

  Similarly, the radar signal processing unit 250b includes a triangular wave generation unit 251b, FFT processing units 252c and 252d, and an object information detection unit 253b, and uses IF signals 3 and 4 output from the radar unit 240b, The distance to the reflecting object, the relative speed, and the direction are calculated.

  The object identification unit 800 includes a detection object identification determination unit 811 that identifies a reflection object using distance information and azimuth information of the reflection object output from the radar signal processing units 250a and 250b, and a radar signal processing unit 250a and 250b. A movement vector detection unit 812 that calculates a movement vector of the reflection object using the output relative velocity (this is V2, V1) and direction (this is θ2, θ1), and the calculated movement A movement vector storage unit 813 that stores vectors, and a preceding vehicle and travel path determination unit 302 are included.

Hereinafter, the operation of each unit of the object identification unit 800 will be described.
The detected object identification determination unit 811 detects the two-dimensional position information of the reflecting object from the distance information and the direction information of the reflecting object detected by the radar signal processing units 250a and 250b, and the detection result is sent to the vehicle control CPU unit 400. At the same time, information on the reflection object observed by the radar units 240a and 240b is extracted and output to the movement vector detection unit 812.

In the movement vector detection unit 812, the relative speeds V1 and V2 and the azimuths θ1 and θ2 of the reflecting objects determined to be detected by the two radar units 240a and 240b by the detected object identification determination unit 811 are expressed by the following formula ( Substituting into 3) and (4), the actual movement direction θ0 and the actual movement vector V0 of the reflecting object (preceding vehicle 602) are calculated.
θ0 = tan ^-1 {(V2cosθ1-V1cosθ2) / (V1sinθ2-V2sinθ1)}… (3)
| V0 | = V1 / cos (θ0-θ1)… (4)

  In the radar units 240a and 240b, the velocity component orthogonal to the radar reception azimuth of the actual movement vector of the moving object cannot be measured, and only the velocity component of the radar reception azimuth is measured (V1, V2). Actually, since there is a component orthogonal to the radar reception azimuth, it can be seen that an actual movement vector exists on the orthogonal auxiliary lines (θ1⊥, θ2⊥). Therefore, the intersection of the auxiliary lines obtained by the two radar units 240a and 240b can be plotted as the moving vector of the moving object. This can be expressed by equations (3) and (4) above.

[Leading vehicle follow-up travel control processing]
FIG. 15 is a flowchart showing the flow of the preceding vehicle follow-up travel control process provided as a program in the ACC system of the second embodiment. Each step will be described below. In addition, the same step number is attached | subjected to the step which performs the same process as Example 1 shown in FIG. 4, and description is abbreviate | omitted.

  In step S11, each of the two radar units 240a and 240b of the radar head unit 700 acquires distance, relative speed, and direction information by the ranging operation, and the process proceeds to step S2.

  In step S12, the movement vector detection unit (back angle detection means, lateral displacement detection means) 812 calculates the movement vector of the preceding vehicle, and the movement vector storage unit 813 stores the calculated movement vector in the memory. The process proceeds to step S6.

  In step S13, the preceding vehicle and travel path determination unit 302 determines whether or not the lateral position of the preceding vehicle is equal to or greater than a predetermined value and the direction of movement vector tends to decrease after increasing. If YES, the process proceeds to step S9. If NO, the process proceeds to step S4.

Next, the operation will be described.
In the radar apparatus according to the first embodiment, since the optical radar is used as the radar apparatus, it is possible to detect the rear angle (body inclination) of the front vehicle from the detection of the pair of reflective reflectors. On the other hand, when the radio wave radar is used as in the second embodiment, the vehicle body inclination of the preceding vehicle is reflected in the reflection intensity and can be detected, but the reflection intensity and the vehicle body inclination are not uniquely related. The vehicle body tilt cannot be detected directly.
Therefore, in the second embodiment, by calculating the movement vector of the preceding vehicle and using the movement vector as a parameter, it is possible to detect the distance information and the azimuth information of the preceding vehicle and obtain the same effects as in the first embodiment. Can do.

Next, the effect will be described.
The preceding vehicle detection apparatus 100 and the ACC system of the second embodiment have the following effects in addition to the effects (1) to (4) and (6) to (8) of the first embodiment.

  (9) A scanning type radar head unit 700 that detects position information of a target from a reflected wave of an electromagnetic wave emitted in front of the host vehicle, and the detected object movement vector detection unit 812 is based on information from the radar head unit 700. To calculate the rear angle of the preceding vehicle. More specifically, in the second embodiment, a pair of radar units 210a and 210b that transmit and receive millimeter-wave radio waves are used as the radar head unit 700, and the detected object movement vector detection unit 812 is measured by both radar units 210a and 210b. The movement vector of the preceding vehicle is calculated from the relative speed. Thereby, similarly to Example 1, the back surface angle can be detected stably.

(Other examples)
Although the best mode for carrying out the present invention has been described with reference to the first and second embodiments based on the drawings, the specific configuration of the present invention is limited to that shown in the first and second embodiments. Instead, design changes that do not change the gist of the invention are included in the present invention.

  For example, in the first embodiment, the lateral G is used as a method of detecting the straight traveling state of the host vehicle from the vehicle behavior, but the straight traveling state may be detected using the yaw rate or yaw moment of the vehicle.

It is a control block diagram which shows the ACC system of Example 1. FIG. 1 is a configuration diagram of a radar head unit 200 of Embodiment 1. FIG. It is a time chart which shows the relationship between a trigger signal, a light emission pulse, a transmission signal, and a light reception signal. It is a flowchart which shows the flow of the preceding vehicle following travel control process with which the ACC system of Example 1 is provided as a program. It is a figure which shows the state which detects a preceding vehicle in a curved road. It is a figure which shows the back angle calculation method of a preceding vehicle. It is a figure which shows the state transition of the preceding vehicle during curve road driving | running | working. It is a time chart which shows the change of the side position and back angle of the preceding vehicle which is running on a curved road. It is a figure which shows the state transition at the time of the preceding vehicle driving | running | working on a straight road changing a lane. It is a time chart which shows the change of the side position and back angle of the preceding vehicle at the time of lane change. It is a control block diagram which shows the ACC system of Example 2. It is a figure which shows the method of calculating the movement vector of a moving object using two radar parts. It is a figure which shows an example of the modulation signal, transmission signal, reflected signal, and IF signal of the radar apparatus of FM-CW system. It is a figure which shows the sensitivity curve of the two receiving antennas in a monopulse system, and the curve for an azimuth | direction detection obtained by dividing | segmenting the intensity difference of two signals by an intensity sum. It is a flowchart which shows the flow of the preceding vehicle following driving | running | working control process with which the ACC system of Example 2 is provided as a program.

Explanation of symbols

100 Leading vehicle detector
200 Radar head
210 Signal transmitter
211 Light Emitting Element
212 Light emission controller
213 Focusing mirror
214 reflection mirror
215 Reflection mirror angle changing section
220 Signal receiver
221 Light receiving element
222 Light receiving lens
223 amplifier
230 Radar drive processor
231 Transmission trigger generator
232 Transmission direction setting section
233 Distance detector
300 Object identification part
301 Grouping processing unit
302 Preceding vehicle and travel path determination unit (curved road determination means, straight running state detection means, lane change determination means)
303 Precedence vehicle lateral position and vehicle body tilt calculation storage unit (back angle detection means, lateral displacement detection means)
400 Vehicle control CPU (vehicle speed control means)
500 Vehicle sensor
501 Horizontal G sensor
502 Vehicle speed sensor
503 ACC switch
601 Own vehicle
602 preceding car
603 Reflector reflection point
610 detection area

Claims (7)

A back angle detection device that detects a back angle that is a traveling angle of the preceding vehicle with respect to the host vehicle;
If the preceding vehicle is not confirmed, constant speed running control is performed to maintain the host vehicle speed at the target vehicle speed, and when the preceding vehicle is confirmed, the preceding vehicle and the preceding vehicle are determined according to the road shape in front of the host vehicle estimated from the rear angle. Vehicle speed control means for performing follow-up running control to maintain the target inter-vehicle distance;
In a vehicle speed control device having
A straight traveling state detecting means for detecting the straight traveling state of the vehicle,
A lane change determination means for determining that the preceding vehicle has changed lanes when the host vehicle is traveling straight and the rear angle decreases after increasing within the target inter-vehicle time of the following traveling control ;
Equipped with a,
The vehicle speed control device, when it is determined that the preceding vehicle has changed lanes during the following travel, the vehicle speed control means shifts to the constant speed travel . A back angle detection device that detects a back angle that is a traveling angle of the preceding vehicle with respect to the host vehicle;
If the preceding vehicle is not confirmed, constant speed running control is performed to maintain the host vehicle speed at the target vehicle speed, and when the preceding vehicle is confirmed, the preceding vehicle and the preceding vehicle are determined according to the road shape in front of the host vehicle estimated from the rear angle. Vehicle speed control means for performing follow-up running control to maintain the target inter-vehicle distance;
In a vehicle speed control device having
Straight-running state detecting means for detecting the straight-running state of the host vehicle;
Lane change determination means for determining that the preceding vehicle has changed lanes when the back angle decreases after increasing during a straight line of the host vehicle;
With
The vehicle speed control means maintains the following traveling control when the host vehicle is traveling straight and the change in the rear angle decreases after the target inter-vehicle time of the following traveling control cannot be detected even after the target inter-vehicle time has elapsed. A vehicle speed control device. In the vehicle speed control device according to claim 1 or 2,
Lateral displacement detection means for detecting lateral displacement, which is the displacement in the vehicle width direction of the preceding vehicle relative to the host vehicle;
If the back angle and the lateral displacement amount continue to increase from when at least one of the rear angle or the lateral displacement amount starts to increase until the host vehicle stops moving straight, the preceding vehicle is curved. A curved road judging means for judging that the vehicle is traveling on the road;
Vehicle speed control apparatus comprising: a. In the vehicle speed control device according to claim 3 ,
When it is determined that the preceding vehicle is traveling on a curved road during the following traveling, the vehicle speed control means performs following traveling control according to a road surface shape of the curved road. . In the vehicle speed control device according to any one of claims 1 to 4,
The vehicle speed control device, wherein the straight traveling state detection means detects a straight traveling state based on a steering angle . In the vehicle speed control device according to any one of claims 1 to 4 ,
The straight-running state detecting means detects a straight-running state based on the vehicle behavior of the host vehicle. In claims 1 vehicle speed control apparatus according to any one of claims 6,
A scanning radar that detects information on a target from a reflected wave of an electromagnetic wave emitted in front of the host vehicle,
The vehicle speed control device characterized in that the back surface angle detection means calculates a back surface angle of a preceding vehicle based on position information from the radar .

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