JPH0763843A - Vehicle mounted radar equipment - Google Patents

Abstract

PURPOSE:To prevent the erroneous detection of roadside objects continued along the road regardless of warning or control, to prevent the erroneous warning in application for the warning of the distance between the vehicles, and to prevent the deterioration in drivability in application for vehicle-speed control. CONSTITUTION:A radar-equipment main body M1 is utilized for the simultaneous detection, warning or control of the relative distance and the relative speed with respect to a target substance based on two beat frequencies. A differentiating means M2 differentiates the relative distance in time and obtains the differentiated speed. In a first comparing means M3, the relative speed of the target substance and the differentiated speed are compared. A prohibiting means M4 prohibits the relative speed and the utilization of the relative speed when the difference between the relative speed and the differential speed in the first comparing means M3 is larger than the specified value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-vehicle radar device,
The present invention relates to an on-vehicle radar device mounted on a vehicle to detect a target object.

[0002]

2. Description of the Related Art Conventionally, various devices have been developed and mounted on a vehicle for the purpose of improving a driver's low operation range and improving safety. Development of a radar device for detecting the is also active. As a radar device, a device using radio waves such as millimeter waves or a device using laser light has been proposed.
A conventional on-vehicle radar device obtains a distance to a first target object by using a low frequency modulation signal as described in JP-A-5-60859, raises the modulation signal frequency, and simultaneously increases the first target object. Determine the cutoff frequency of the low-pass filter that cuts off the beat signal component corresponding to
There is a frequency modulation radar device that detects a second target object in front of it.

[0003]

In the frequency modulation radar device such as the conventional device, it is possible to simultaneously calculate the relative distance and relative velocity to the target object. However, especially when a roadside object that is continuous along a road such as a guardrail on a curved road exists within the radar detection range, the relative distance of the roadside object does not change with time and is substantially the same as the speed of the host vehicle. Is detected as a target object having a relative velocity of. For this reason,
Depending on the relationship between the relative distance and relative speed of the roadside object, it is possible that the roadside object may be mistakenly recognized as a dangerous object even though the vehicle is traveling along a curve. However, when applied to vehicle speed control, there was a problem that dryness deteriorates.

The present invention has been made in view of the above points,
By comparing the relative speed and the differential speed obtained by differentiating the relative distance, it is possible to prevent erroneous detection of roadside objects that continue along the road unrelated to the alarm or control, and to prevent false alarms when applied to the inter-vehicle warning. It is an object of the present invention to provide a vehicle-mounted radar device that prevents the deterioration of drivability when applied to vehicle speed control.

[0005]

FIG. 1 shows the principle of the present invention.

The radar apparatus main body M1 simultaneously measures the relative distance and the relative velocity with respect to the target object.

The differentiating means M2 obtains a differential speed by differentiating the relative distance with respect to time.

The first comparing means M3 compares the relative speed and the differential speed of the target object.

The prohibiting means M4 prohibits the use of the relative distance and the relative speed when the difference between the relative speed and the differential speed in the first comparing means is a predetermined value or more.

The second comparing means M5 compares the own vehicle speed with the relative speed, and only when the difference between the own vehicle speed and the relative speed is less than a predetermined value, the second comparing means M5 and the first comparing means. The comparison means and the prohibition means are activated.

Further, the safety distance setting means M6 obtains the safety distance to be used for the warning determination based on the own vehicle speed and the relative speed or the differential speed for each of the plurality of target objects.

[0012]

In the present invention, when the difference between the relative speed and the differential speed obtained by differentiating the relative distance is equal to or more than a predetermined value, the relative speed and the relative distance are regarded as those of a roadside object which is continuous along the road, and the prohibiting means. The use of measurement data is prohibited by M4.

Further, only when the difference between the own vehicle speed and the relative speed is less than a predetermined value, that is, when the relative motion between the own vehicle and the target object is small, the differentiating means M2, the first comparing means M3, and the prohibiting means M4. Are operated to prevent useless operation of the means M2 to M4.

Furthermore, in order to obtain the safety distance used for the alarm determination for each of the plurality of target objects, it is possible to separately issue the alarm for each target object.

[0015]

FIG. 2 shows a block diagram of the device of the present invention. In the figure, the transmission side circuit includes a carrier wave generator 10 and a frequency modulator 1.
2, a modulation voltage generator 14, a circulator 16, and a transmission antenna 18. A carrier wave is output from the carrier wave generator 10 and supplied to the frequency modulator 12.
On the other hand, the modulation voltage generator 14 outputs a triangular wave whose amplitude changes in a triangular shape, and the frequency modulator 12 outputs a modulated wave.
Is supplied to. As a result, the carrier wave from the carrier wave generator 10 is frequency-modulated, and a transmission signal whose frequency changes in a triangular shape over time is output. This transmission signal is supplied to the transmission antenna 18 via the circulator 16 and radiated toward the object to be detected. On the other hand, a part of the transmission signal is supplied to the mixer 22 of the receiving side circuit described later via the circulator 16.

The receiving side circuit includes a receiving antenna 20, a mixer 22, an amplifier 24, a filter 26, a fast Fourier transform processor (FFT signal processor) 28, and a target recognizer 3.
0, a risk determiner 32, and an alarm 34.
The reflected wave from the detected object is received by the receiving antenna 20 and supplied to the mixer 22. In the mixer 22, the reception signal and a part of the transmission signal from the circulator 16 are combined by a difference calculation to generate a beat signal. Mixer 22
The beat signal from is amplified by the amplifier 24 and supplied to the FFT signal processor 28 via the anti-aliasing filter 26. The FFT signal processor 28 obtains the power spectrum of each of the frequency rising portion and the frequency falling portion and supplies them to the target recognizer 30.

The target recognizer 30 has a frequency increasing portion,
The peaks of the respective power spectra of the descending parts are detected and paired to form a pair of peaks corresponding to each target object. The relative velocity frequency fd obtained from the peak frequency fup of the frequency rising part and the peak frequency fdown of the frequency falling part of this pair of peaks, the distance frequency fr fd = (fdown-fup) / 2 (1) fr = (fdown + fup ) / 2 (2) and fd = 2 · ΔV / C · f0 (3) fr = 4fmΔf / C · R (4) where ΔV: relative speed, C: speed of light, f0: center frequency,
The relative distance R and the relative speed ΔV are simultaneously obtained from fm: modulation frequency, Δf: frequency shift width, R: relative distance. Here, “simultaneous” means that the method of obtaining the relative velocity ΔV by differentiating the relative distance R with respect to time is not included. After this, the safety distance calculated in advance or calculated according to the traveling state of the own vehicle and the relative distance are compared in magnitude,
If it is less than the safe distance, it is judged as dangerous and the alarm 34
To notify the driver.

FIG. 3 shows a flowchart of the first embodiment of the recognition processing executed by the target recognizer 30. This process is executed every several tens of msec. In the figure, in step S10, the relative distance R and the relative velocity ΔV of the target object (ΔV is the approaching direction is positive) are calculated by the equations (1) to (4), and then the own vehicle speed SPD is calculated in step S12. To do. In step S14, the vehicle speed SPD is subtracted from the relative speed ΔV to obtain the speed difference A, and in step S16, the absolute value of the speed difference A is the stationary object determination threshold value α (for example, 5 km / h or 0.1 × SP.
It is determined whether or not D) is exceeded.

If | A |> α, the target object is moving, so the safety distance is calculated according to the running state of the vehicle in the risk determination processing of step S18, and this is compared with the relative distance R. Therefore, an alarm is issued when the distance is less than the safe distance.
This step S18 is executed and the process is ended.

If | A | ≦ α, the routine proceeds to step S20, where the relative distance Rn obtained this time is subtracted from the relative distance Rn- _i (i is 1) obtained in the past, and the distance differential relative speed Δ
Calculate Rn. It is assumed that the Rn- ₁ detection time point and the Rn detection time point are separated by a unit time. Then step S
At 22, the average distance differential relative velocity ΔR is calculated by the following equation.

ΔR = (ΔRn + ΔRn ₋₁ + ... + ΔR
n _−j ) / (j + 1) Further, in step S24, the difference B between the relative velocities ΔR and ΔV.
Ask for. In step S26, it is determined whether or not the absolute value of the difference B exceeds the roadside object determination threshold value β.

Here, a roadside object which is continuous along a road such as a guardrail on a curved road has a differential relative speed ΔR of approximately 0 and a difference B exceeding a threshold value β in a state where the roadside object travels along the curved road. In a situation where the vehicle is hit by a stopped vehicle or a roadside object, the relative velocities ΔR and ΔV become substantially the same and the difference B
Is less than or equal to the threshold β. Therefore, in the case of | B |> β, the roadside object does not require the risk determination, and the process ends.

If | B | ≦ β, it is assumed that the target object is in a rear-end collision, and the process proceeds to the risk determination processing in step S28, and the safety distance of a predetermined value (for example, several tens of meters) and the relative distance R are compared. Then, if the distance is less than this safety distance, an alarm is issued. This step S28 is executed, and the process ends.

The above steps S14 and S16 correspond to the second comparing means M5, steps S20 to S22 correspond to the differentiating means M2, and steps S24 and S26 correspond to the first comparing means M3 and the prohibiting means M4. .

As described above, when the difference between the relative speed and the differential speed obtained by differentiating the relative distance is equal to or greater than a predetermined value, the relative speed and the relative distance are regarded as those of a roadside object continuous along the road, and the prohibiting means M4. This prohibits the use for alarm or control, prevents erroneous detection of roadside objects that are continuous along the road, and prevents erroneous inter-vehicle warning.

The steps S20 to S28 are executed only when the difference between the vehicle speed and the relative speed is less than a predetermined value, that is, when the relative motion between the vehicle and the target object is small, and the steps S20 to S28 are wasteful. It is possible to prevent unnecessary execution and increase the processing speed.

FIG. 4 shows a flowchart of the second embodiment of the recognition processing executed by the target recognizer 30. This process is executed every several tens of msec. In the figure, 1 is set to the variable i in step S40. In step S41, (1)-
The relative distances R _{1 to} Rn and the relative velocities ΔV _{1 to} ΔVn (ΔVi is the approach direction is positive) of the n target objects are calculated by the equation (4), and then the vehicle speed SPD is calculated in step S 42.
Is calculated. In step S44, the relative speeds ΔV _{1 to} ΔV
The own vehicle speed SPD is subtracted from each n to obtain the speed differences A _{1 to} An, and it is determined in step S46 whether the absolute value of the speed difference Ai exceeds the stationary object determination threshold α. ｜ Ai ｜ ＞ α
In the case of, since the target object is moving, step S54
Proceed to. If | Ai | ≦ α, the routine proceeds to step S48, where the relative distance Rim- _j (i is, for example, 1) obtained in the past is subtracted from the relative distance Rim obtained this time to calculate the distance differential relative speed ΔRim. Next, in step S49, averaging is performed by the following equation to obtain an average distance differential relative velocity ΔRi.

ΔRi = (ΔRim + ΔRim ₋₁ + ... + Δ
Rim _−k ) / (k + 1) Further, in step S50, the difference Bi between the relative velocities ΔRi and ΔVi is obtained. In step S52, it is determined whether or not the absolute value of the difference Bi exceeds the roadside object determination threshold value β. If | Ai |> α in step S46 and the i-th target object is moving, or if | Bi | ≦ β in step S52 and the vehicle is in a situation of colliding with the i-th target object, the safety distance setting means Go to step S54 corresponding to M6,
The safe distance Rki is calculated from the vehicle speed SPD and the relative speed ΔVi. This safety distance Rki increases as the SPD increases, and increases as ΔVi increases. Next, in step S56, the relative distance Ri is compared with the safety distance Rki, and R
When i ≦ Rki, the i-th target object is set as an alarm on target in step S58, and when i> Rki, the i-th target object is set as an alarm off target in step S60. If | Bi |> β is established in step S52 and the vehicle is traveling along a roadside object that is continuous along a road such as a guardrail, the i-th target object is set as an alarm off target in step S60.

Next, in step S62, it is determined whether or not the variable i is greater than or equal to the total number n of target objects, and if i <n, step S62.
At 64, i is incremented by 1 and the process proceeds to step S46, and steps S46 to S62 are repeated. If i ≧ n, it is determined in step S66 whether or not there is an alarm on target. If there is no alarm on target, the alarm is turned off in step S68, and if there is an alarm on target, step S7.
At 0, the alarm device 34 is instructed to issue an alarm, and the process ends.

As described above, in order to obtain the safety distance used for the predetermined warning for each of the plurality of target objects, the warning can be issued separately for each target object. Therefore, even when there is a stopped vehicle ahead of the preceding vehicle and the preceding vehicle changes lanes, it is possible to give an early warning to both the preceding vehicle and the stopped vehicle.

Here, as shown in FIG. 5, the case where the radar-equipped vehicle 41 travels on a curved road having the roadside object 40, and the preceding vehicle 43 and the roadside object 40 exist in the radar detection area 42 shown by the diagonal lines will be described. To do. In this case, the preceding vehicle 43
Is traveling at substantially the same speed as the radar-equipped vehicle 41, the first relative distance Ri and the first relative speed ΔV ₁ with the preceding vehicle as the target object are indicated by the solid line and the alternate long and short dash line in FIG. 6A, respectively. It becomes substantially constant as shown, and in this case, the first safety distance Rk ₁ is the first
If the relative distance R ₁ is smaller than R ₁ , the alarm is not issued.

In a situation where the radar-equipped vehicle 41 collides with the roadside object 40 due to drowsiness or the like, the second relative distance R ₂ and the second relative speed ΔV ₂ with the roadside object 40 as the target object are shown in FIG.
As indicated by the solid line and the one-dot chain line in (B), an alarm is issued at the time t ₁ when the second relative distance R ₂ becomes less than the safety distance Rk ₂ .

In the above embodiment, the relative speed and the relative distance are used for the vehicle-to-vehicle warning, but the present invention is not limited to this and may be applied to the follow-up traveling control or the vehicle speed control.

In the above embodiment, the frequency modulation radar has been described as an example, but the present invention is not limited to this, and the relative distance and the relative speed can be calculated by the equations (1) to (4) such as the dual frequency radar and the intermittent frequency modulation radar. However, the radar is not limited to the above embodiment.

[0035]

As described above, according to the on-vehicle radar device of the present invention, by comparing the relative speed with the differential speed obtained by differentiating the relative distance, the roadside object continuous along the road unrelated to the alarm or control. It is possible to prevent erroneous detection, prevent erroneous alarms when applied to inter-vehicle alarms, and prevent deterioration of drivability when applied to vehicle speed control, which is extremely useful in practice.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a block diagram of the device of the present invention.

FIG. 3 is a flowchart of a first embodiment of recognition processing.

FIG. 4 is a flowchart of a second embodiment of recognition processing.

FIG. 5 is a diagram for explaining the present invention.

FIG. 6 is a diagram for explaining the present invention.

[Explanation of symbols]

 M1 radar device main body M2 differentiating means M3 first comparing means M4 inhibiting means M5 second comparing means M6 safe distance setting means 10 carrier wave generator 12 frequency modulator 14 modulation voltage generator 16 circulator 18 transmitting antenna 20 receiving antenna 22 mixer 24 amplifier 26 filter 28 FFT signal processor 30 target recognizer 34 alarm device

Claims (3)

[Claims] 1. An in-vehicle radar device for simultaneously measuring a relative distance and a relative velocity with respect to a target object, the differential means for differentiating the relative distance with time to obtain a differential velocity, and a relative velocity and a differential velocity of the target object. It has first comparing means for comparing, and prohibiting means for prohibiting the use of the relative distance and the relative speed when the difference between the relative speed and the differential speed in the first comparing means is a predetermined value or more. In-vehicle radar device. 2. The on-vehicle radar device according to claim 1, further comprising a second comparing means for comparing the own vehicle speed and the relative speed, wherein the second comparing means compares the own vehicle speed and the relative speed with each other. The in-vehicle radar device is characterized in that the differentiating means, the first comparing means, and the prohibiting means are operated only when the difference between the two is less than a predetermined value. 3. The in-vehicle radar device according to claim 2, further comprising a safety distance setting unit that obtains a safety distance used for determination of the alarm based on the own vehicle speed and the relative speed or differential speed of each of the plurality of target objects. An on-vehicle radar device characterized by the above.