JP2830831B2 - Relative speed correction method for automotive radar system - Google Patents

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 for measuring the distance and relative speed between a vehicle and a vehicle traveling forward and backward, which is used for preventing collision of a vehicle .
And a method for correcting the relative speed of the vehicle .

[0002]

2. Description of the Related Art Conventionally, this type of on-vehicle radar device measures the distance and relative speed between a vehicle traveling forward and backward, and is used particularly for preventing collision of a vehicle ahead. . Further, the on-vehicle radar apparatus uses a millimeter wave radio wave and continuously transmits an FM modulated wave by a triangular wave (FM-CW radar).

[0003] The FM-CW radar transmits a continuous signal FM-modulated by a triangular wave toward an obstacle such as an automobile ahead, and receives the reflected wave reflected by the obstacle. A beat signal obtained by mixing the transmission signal and the reception signal in this case is generated, and the generated beat signal is converted into a discrete frequency spectrum by, for example, FFT (Fast Fourier Transform), and the The distance and the relative speed to an obstacle such as a car are calculated.

[0004] The calculation of the distance and the relative speed to an obstacle such as a car uses a peak frequency indicating an obstacle such as a car ahead in a beat signal corresponding to an ascending section and a descending section of a triangular wave signal. ing.

FIG. 8 is a diagram for explaining the calculation of the distance and the relative speed between a beat signal and an obstacle such as an automobile ahead. FIG. 8A shows a peak frequency fa in an up section.
FIG. 8B shows the peak frequency fb in the falling section. From the peak frequency fa and the peak frequency fb in the falling section, the distance R and the relative speed V are proportional to the sum value and difference value of the respective peak frequencies fa and fb. That is, it is obtained by the following equations (1) and (2).

Distance R = A · ((fa + fb) / 2) (1) Relative Speed V = A · ((fa−fb) / 2) (2) A: Constant

The characteristic of the value of the difference between the relative speed and the peak frequency is such that when the relative speed V is zero as shown in FIG. You. Therefore, an error in the difference frequency when the relative speed V is zero affects the prediction of a collision with an obstacle.

Such processing is performed by a microprocessor (M
PU), and determines whether or not to collide after a certain period of time based on the distance and the relative distance to an obstacle such as an automobile ahead calculated by the MPU. If a danger of a collision is expected and the driver cannot make an emergency stop by the brake operation, the microprocessor controls the brake braking to avoid the collision. Therefore,
In order to perform high-precision brake braking, detection accuracy of a distance and a relative distance to an obstacle such as an automobile ahead is important.

As an example of detecting the distance and the relative distance from such an obstacle, a "radar apparatus" of JP-A-5-264726 and a "distance / velocity measuring apparatus" of JP-A-5-333143 are disclosed. Are known. In the former conventional example, the FM-CW radar device measures its own absolute speed together with the relative distance and relative speed to the target. In the latter conventional example, the beat frequency is analyzed,
This prevents the peak frequency due to the noise signal from approaching and losing its target.

[0010]

However, in the above-mentioned prior art, the beat signal obtained by mixing the transmission signal and the reception signal due to the design of the transmission / reception system for obtaining the beat signal, manufacturing error, ambient temperature and aging. In some cases, the signal may have a difference between the up section and the down section of the triangular wave signal, causing a frequency shift.

As a result, for example, the difference frequency (f
v) As shown in the relative velocity (V), the peak frequency of the beat signal in the rising section and the falling section of the triangular wave signal deviates (error) from the normal solid line value as shown by the dotted line. If the detection error of the relative speed occurs, it is difficult to accurately predict the collision at a high speed.

The present invention has been made to solve the above-mentioned problems in the prior art, and includes a design of a transmission / reception system for obtaining a beat signal, a manufacturing error, an ambient temperature, and a peak of a reflected wave generated with aging. Provided is a relative speed correction method and a vehicle-mounted radar device that can accurately detect a relative speed and accurately detect a relative speed and improve the reliability of collision prediction.

[0013]

According to a first aspect of the present invention, an FM-modulated wave based on a triangular wave signal is transmitted to a moving object to be measured, and the reflected wave is transmitted to the moving object from the reflected wave. In the relative speed correction method in the vehicle-mounted radar device to correct the relative speed when measuring the distance and the relative speed of, to extract the frequency spectrum of the reflected wave signal,
A difference between the peak frequencies of the beat signals corresponding to the rising and falling sections of the triangular wave signal in the fixed setting section is detected, and the difference between the maximum value and the minimum value of the difference is obtained, and the value of this difference is set in advance. It was less than the value and the triangular wave signal
Peak frequency of the beat signal corresponding to the up section and the down section
When the sum of numbers is detected and the difference between the maximum and the minimum of this sum is obtained,
In both cases, when the difference value is smaller than a preset value, the difference value of the peak frequency is successively averaged, and the average value obtained at the end of the set section falls below the upper limit of the relative speed correction value. The average value is detected as a relative speed correction value.

According to a second aspect of the present invention, there is provided a method for correcting a relative velocity in a vehicle-mounted radar apparatus, wherein a frequency spectrum is obtained by an FFT process.

According to a third aspect of the present invention, there is provided a method for correcting a relative speed in an on-vehicle radar device, wherein when a setting condition of a relative speed correction value is satisfied in a set section, a maximum value of a difference between peak frequencies in the set section is set. The difference between the minimum values is used as a stability determination condition in the next unit period of the distance and the relative speed.

According to a fourth aspect of the present invention, there is provided a method for correcting a relative speed in an on-vehicle radar device, wherein when a condition for setting a relative speed correction value is satisfied in a set section, an average value of sums of peak frequencies in the set section is calculated. The configuration is used for the next stability determination condition in the unit period of the distance and the relative speed.

According to a fifth aspect of the present invention, there is provided a method for correcting a relative speed in an on-vehicle radar device, wherein when a condition for setting a relative speed correction value is satisfied in a set section, the distance and relative speed in the set section are stable during a unit period. The time exceeding the determination time is used as the next stability determination time.

According to a sixth aspect of the present invention, there is provided a method for correcting a relative speed in an on-vehicle radar device, wherein an abnormality is notified when an average value obtained at the end of a set section exceeds an upper limit of a correction value of the relative speed.

According to the relative velocity correcting method for a vehicle-mounted radar device according to the present invention having such a configuration, an FM modulated wave based on a triangular wave signal is continuously transmitted to a moving body, and the reflected wave signal is transmitted. , The difference between the peak frequencies of the beat signals corresponding to the rising section and the falling section of the triangular wave signal in a certain set section in the frequency spectrum extracted by the FFT processing.

When the difference between the maximum value and the minimum value of the difference is smaller than a preset value, and the sum of the peak frequencies and the difference between the maximum value and the minimum value are smaller than the preset value,
The average value of the difference between the peak frequencies is sequentially calculated, and the average value obtained at the end of the set section, which is below the upper limit of the relative speed correction value, is detected as the relative speed correction value.

[0021] Thus, the transmission and reception system designed for obtaining a beat signal, a manufacturing error, deviation of the peak frequency of the reflected waves generated due to the ambient temperature and aging is reliably corrected. That is, the relative speed is corrected with high accuracy.

According to the relative speed correction method for an on-vehicle radar device according to the present invention, when the setting condition of the relative speed correction value is satisfied in the set section, the value of the difference between the peak frequencies in the set section is established. Is used as a condition for determining stability in the next unit period of distance and relative speed. In addition, the average value of the sum of the peak frequencies in the set section is used as the next stability determination condition, and the time exceeding the stability determination time in the set section is used as the next stability determination time.

[0023] As a result, sequentially become severe condition determination of the correction value detection from the next, the correction value of the relative speed is set to the latest value, the relative speed is corrected with higher accuracy.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an on- vehicle radar device according to the present invention.
An embodiment of the relative speed correction method in will be described in detail with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of an on-vehicle radar device according to an embodiment. The on-vehicle radar device shown in FIG. 1 is mounted on an automobile, and has a transmitting antenna 2 for transmitting an FM modulated wave toward an automobile 1 as an obstacle, and a receiving antenna for receiving a reflected wave from the automobile 1. And an antenna 3.

Further , this radar apparatus mounted on a vehicle has a radar head 4 for outputting a beat signal generated by mixing an FM-modulated wave signal to the transmitting antenna 2 and a reflected signal from the receiving antenna 3; A low-pass filter 5 for producing a beat signal, an amplifier 6 for amplifying and outputting the beat signal from the low-pass filter 5, and an amplifier 6
And an A / D converter 7 for converting a beat signal from the A / D into a digital signal.

Furthermore, the in-vehicle radar apparatus, the triangular-wave signal generator 8 which outputs a triangular wave signal to the radar head 4
And a microprocessor (MPU) 9 for performing prediction and determination of a collision with the automobile 1 and processing of detecting a relative speed correction value as will be described later in detail, and this MPU 9 predicts a collision with the automobile 1 and It has a drive circuit 10 that outputs a drive signal for braking when it is determined that it is difficult for the driver to avoid the brake operation. The drive circuit 10 is provided in a brake hydraulic system.

Furthermore, by a drive signal from the drive circuit 10, a brake device 11 of a motor vehicle which performs a braking operation of a vehicle equipped with in-vehicle radar device of this embodiment, MP
An alarm 12 that outputs an alarm when the radar head 4 or the like operates abnormally under the control of U9 is provided.

The MPU 9 has a function block executed by the following control program. A / D converter 7
A frequency signal is analyzed by FFT processing on the discrete value beat signal converted into a digital signal from the A / D converter to extract a spectrum, control the sampling in the A / D converter 7, and control the sampling in the triangular wave signal generator 8. It has a spectrum extractor 9a for controlling the output of the triangular wave signal.

Furthermore, the distance and the relative speed between the peak frequency detector 9b for detecting a peak frequency from the frequency spectrum spectrum extraction unit 9a is extracted from the peak frequency of the peak frequency detector 9b detects a car 1 And a distance / relative speed detecting section 9c for detecting the distance.

Further , the stability of the distance and relative speed obtained by the distance / relative speed detector 9c in a unit period is determined, and the relative speed corresponding to the difference between the peak frequencies of the rising section and the falling section of the triangular wave signal is corrected. A relative speed correction value detection unit 9d that calculates and outputs a value is provided. Furthermore, a collision with the automobile 1 is predicted based on the distance and the relative speed obtained by the distance / relative speed detection unit 9c. When it is determined that it is difficult to avoid the collision by the driver's braking operation, the braking is performed. A collision prediction unit 9e that outputs a braking signal to the drive circuit 10 shown in FIG.

FIG . 2 is a block diagram showing a detailed configuration of the radar head 4 in FIG. The radar head 4 of FIG.
A voltage controlled oscillator (VCO) that outputs an FM modulated wave signal based on the triangular wave signal from the triangular wave signal generator 8 in FIG.
4a and a directional coupler 4b for transmitting an FM modulated wave signal to the transmitting antenna 2. Further, the reflected wave signal from the receiving antenna 3 and the F signal detected by the directional coupler 4b are used.
It has a mixer 4c for outputting a beat signal mixed with an M-modulated wave signal, and an amplifier 4d for amplifying the beat signal from the mixer 4c and outputting it to the low-pass filter 5 in FIG.

Next, the operation of this embodiment will be described. FIG. 3 is a flowchart showing the processing procedure of the collision prediction determination, and FIG. 4 is a diagram for explaining the processing state of the collision prediction determination. 3 and 4, MP
U9 performs a process of predicting and judging a collision with the automobile 1 and detecting a relative speed correction value, and is reset and started after a predetermined time by turning on the automobile equipped with the on-vehicle radar device. Execute

[0033] First of all, to handle the initialization in step S1. In this case, the stability determination flag SDF described later
, The A / D converter 7 count ADCNT, the previous distance frequency average value fRAVELT, the stability determination count SDCNT, and the relative speed correction value αV are initialized.

Next, FIG. 4 by an instruction from the triangular-wave signal generator 8 is a spectrum extraction unit 9a at the point P1 in the main routine shown in step S2 Figure 4 (c) (a)
Is output to the radar head 4. In the radar head 4, an FM modulated wave signal is generated by the VCO 4 a in FIG. 2 and transmitted to the automobile 1 through the directional coupler 4 b and the transmitting antenna 2. This FM modulated wave is reflected by the automobile 1, and the reflected wave is received by the receiving antenna 3. The mixer 4c outputs a beat signal shown in FIG. 4 (b) in which the reflected wave signal and the FM modulated wave signal detected by the directional coupler 4b are mixed. The beat signal from the mixer 4c is output to the low-pass filter 5 in FIG.
Further, the signal is input to the A / D converter 7 through the amplifier 6.

In step S3, the spectrum extracting unit 9a
, And the beat signal (beat data) of the digitized digital signal is stored in a RAM (not shown) in the MPU 9. This conversion into beat data is executed at regular sampling times.

[0036] For example, in step S4, performs a sampling monitoring such as timer interrupts, and executes the determination whether the A / D count ADCNT of the A / D converter 7 has reached a prescribed number ADT. If the A / D count ADCNT has not reached the specified number of times ADT (No), in step S5, the A / D count ADCNT is incremented, and the process returns to the digital signal conversion in step S3.

On the other hand, in step S4 A / D count ADCN
If T has reached the specified number of times ADT (Yes), step S
At 6, the A / D count ADCNT is cleared. Next, in step S7, the triangular wave signal generator 8 outputs the triangular wave signal shown at point P2 to the radar head 4 in the main routine shown in FIG.
The operation is stopped by the instruction from a, and the storage of the beat data of the discrete value data in the up section and the down section in the triangular wave signal is completed.

Next, in step S8, the frequency spectrum of the beat data up section in the triangular wave signal spectrum extracting unit 9a is extracted, the peak frequency detector 9b detects a peak frequency fa. Further, in step S9, the peak frequency fb is detected from the frequency spectrum of the beat data in the falling section of the triangular wave signal. Next, in step S10, the distance / relative speed detector 9c calculates the distance R to the automobile 1 from the peak frequencies fa and fb by the following equation (3). Distance R = A · ((fa + fb) / 2) (3) A: constant

A relative speed correction value detection process is executed by a subroutine shown in FIG. FIG. 5 is a flowchart showing the processing procedure for detecting the relative speed correction value, and FIG. 6 is a diagram for explaining the processing for detecting the relative speed correction value. 5 and 6, first, in step S1
6, the relative speed correction value detecting unit 9d determines whether or not the stable state of the distance data fR and the relative speed data fv corresponding to the distance and the relative speed detected by the distance / relative speed detecting unit 9c is being determined. The status of the stability determination flag SDF is determined to be "0, 1" using bits.

In step S16, if the status of the stability determination flag SDF is "0" (No), since the determination of the stable state is not in progress, the initialization for starting the stable state is performed as follows.
In step S18, the relative speed data fv in the stability determination section
The maximum value fVMAX and the minimum value fVMIN of are respectively initialized to the peak frequency “fa−fb”, and step S19 is performed.
And the maximum value fRMAX and the minimum value fRMIN of the distance data fR in the stability determination section are respectively set to the peak frequency “fa + f”.
b ”. Thereafter, the status of the stability determination flag SDF is set to "1" in step S20, and the flow advances to step S12 of the main routine shown in FIG.

At step S16 in FIG .
When the status of the SDF is "1" (Yes), the determination of the stable state is in progress, and in step S17, the beat signal "fa-fb" is set in the relative speed data fv.
The beat signal “fa + fb” is set in the distance data fR.

[0042] Further, as shown in FIG. 6, the preset in stability determination time, the maximum value fVMAX and minimum value of the difference between the fVMIN relative velocity data fv, distance data fR
The stable state is determined based on whether or not the difference between the maximum value fRMAX and the minimum value fRMIN is within a predetermined fixed value width.

[0043] Therefore, the relative velocity data fv compared with the maximum value FVMAX in step S21 in FIG. 5, when the relative velocity data fv is larger than the maximum value fVMAX (Yes),
In step S22, the relative speed data fv is set to the maximum value fVMAX.
And the maximum value fVMAX of the relative speed data fv is updated, and the process proceeds to step S25. On the other hand, if the relative speed data fv is smaller than the minimum value fVMIN in step S21 (No), the relative speed data fv is compared with the minimum value fVMIN in step S23. In this comparison, the relative speed data fv
Is smaller than the minimum value fVMIN (Yes), the relative speed data fv is set to the minimum value fVMIN in step S24, and the minimum value fVMIN of the relative speed data fv is updated.
Proceed to step S25.

In step S23, the relative speed data f
If v is greater than or equal to the minimum value fVMIN (No), the minimum value fVMI
Step S25 without updating both N and the maximum value fVMAX.
Proceed to. In step S25, a difference between the maximum value fVMAX and the minimum value fVMIN is obtained, and a stable reference width fVSW for determination is determined.
Compare with In this comparison, the maximum value fVMAX and the minimum value fVMI
If the difference from N is equal to or greater than the stability reference width fVSW (No), it indicates that the relative speed data fv has deviated from the stability reference width fVSW, and the status of the stability determination flag SDF is cleared to "0" in step S32. Then, the stability determination state is cancelled, and the process returns to the main routine.

[0045] When the difference between the maximum value fVMAX and minimum fVMIN is less stable reference range fVSW in step S25 (Ye
s) In step S26, the k-th average value fVAVE (k) of the relative speed data fv in the stability determination section is obtained by the following equation (4). fVAVE (k) = {(k-1) fVAVE (k-1) + fv} / k (4) The data of this average value fVAVE (k) is converted to MPU9 in FIG.
In a RAM (not shown).

Next, examine the stability of the distance data fR as in the case of the relative velocity data fv. First, in step S27, the distance data fR is compared with the maximum value fRMAX, and if the distance data fR is larger than the maximum value fRMAX (Ye
s) In step S28, the distance data fR is set to the maximum value fRMA.
X is set, updated, and the process proceeds to step S31. On the other hand, if the distance data fR is equal to or smaller than the maximum value fRMAX in step S27 (No), the distance data f
R is compared with the minimum value fRMIN, and if the distance data fR is smaller than the minimum value fRMIN, the distance data fR is set to the minimum value fRMIN in step S30, updated, and step S30 is performed.
Go to 31. On the other hand, in step S29, the distance data f
If R is equal to or greater than the minimum value fRMIN (No), the distance data f
The process proceeds to step S31 without updating both the maximum value fRMAX and the minimum value fRMIN of R.

In step S31, the difference between the maximum value fRMAX and the minimum value fRMIN of the distance data fR is compared with a stability reference width fRSW for determining stability, and the difference between the maximum value fRMAX and the minimum value fRMIN is equal to or greater than the stability reference width fRSW. In the case of (N
o), indicating that the distance data fR has deviated from the stability reference width fRSW.
F is cleared to "0", the stability determination state is cancelled, and the routine returns to the main routine. On the other hand, in step S31, if the difference between the maximum value fVMAX and the minimum value fVMIN is equal to or smaller than the stability reference width fVSW (Yes), it is checked in step S33 whether a predetermined stability determination time has elapsed.

In step S33, the stability determination frequency count SDCNT is compared with a predetermined stability determination time SDT, and the stability determination frequency count SDCNT is determined as the stability determination time.
If smaller than SDT (Yes), in step S35, the stability determination count SDCNT is incremented, and the process returns to the main routine. One step, if the stability determination count SDCNT is longer than the stability determination time SDT in step S33 (N
o) indicates that the stability determination time has elapsed, and proceeds to step S34 to clear the stability determination count SDCNT to "0".

In step S36, the average value fVAVE of the relative speed data fv is compared with the upper limit value fV0FF of the relative speed correction value. ,
Average value fVAVE of relative speed data fv in the stability determination section
Is stored in a not-shown RAM or the like in the MPU 9 in FIG. 1, and the process returns to the main routine.

On the other hand, since at step S36 when the average value fVAVE is above the upper limit fV0FF (No), it is difficult to correct the deviation of the peak frequency corresponding to the interval falling between the peak frequency corresponding to the up section of the triangular wave signal, Step S
At 38, the MPU 9 determines that the operation of the radar head 4 or the like is abnormal. An alarm signal is output from the relative speed correction value detection unit 9d to the alarm 12, and the alarm 12 is turned on and the like. After this process, the process ends without returning to the main routine.

[0051] via the step S37, the relative speed correction value detection routine, determined by equation (5) below versus speed V by step S12 in FIG. Relative speed V = A · (fa−fb−αV) / 2 (5) A: Constant The relative speed correction value αV is a relative speed correction value detection shown in FIG. 5 which is a subroutine (step S11) in FIG. It was obtained in a routine.

[0052] By the processing up to step S12, the distance R and the corrected relative velocity V is determined, step S
13, the braking distance r of the vehicle equipped with the on-vehicle radar device of this embodiment is calculated from the relative speed V. Then, in step S14, a collision is predicted by the collision prediction unit 9e in the MPU 9 shown in FIG. When it is determined that it is difficult to avoid the collision by the driver's brake operation in the collision prediction, the process proceeds to step S
At 15, the drive circuit 10 outputs a drive signal for braking the brake device 11.

Meanwhile, at step S14, if the distance R is sufficient for braking distance r, as there is no possibility of a collision, without brake control, again, the distance and the relative velocity between the vehicle 1 Return to step S2 for measurement. Thereafter, the MPU 9 controls again to output the triangular wave signal at the point P3 shown in FIG. 4, and executes the subsequent processing.

[0054] In the relative speed correction value detection routine shown in subroutine Thus in FIG. 3 (step S11, FIG. 5), the distance data fR and the relative velocity data fv indicating the distance between the motor vehicle 1 is stable. As a result, relative rawness correction detection for giving a relative speed correction value with the average value of the relative speed data fv obtained at the end of the stability determination section is performed. In the relative speed correction value detection routine, a correction value is calculated every time the stability determination condition is satisfied, and the distance and the relative speed can be measured by the updated relative speed correction value αV.

[0055] However, the relative speed correction value detection routine during traveling, detects the correction value of the relative velocity at a distance or a state where the relative speed is changed between the car 1 of an obstacle. Therefore, the correction value of the relative speed at the time when the stability determination condition is satisfied needs to be more accurate than the previous correction value, and the brake braking is controlled by the detected relative speed. Is required. That is, even after the correction value is set, it is necessary to obtain a more accurate correction value.

FIG . 7 is a flowchart showing a procedure for detecting a relative speed correction value in another example for obtaining high accuracy. This process is a subroutine of step S11 shown in FIG.
Correction value detection is performed based on the following conditions. (1) Distance data fR and relative speed data fv during the stability determination section
In order to determine whether or not is stable, the k-th maximum value fVMAX (k) of the relative speed data fv during the stability determination section
And the minimum value fVMIN (k) is the maximum value fVMAX (k) of the relative speed data fv obtained during the previous stability determination section.
−1) is smaller than the difference Δfv between the minimum value fVMIN (k−1).

[0057] In other words, the conditions that satisfy the following equation (6). MAXfV (k) −MINfV (k) <Δfv Δfv = MAXfV (k−1) −MINfV (k−1) (6)

[0058] (2) the average value of the stability determining k-th average value of the distance data fR in section FRAVE (k) distance is obtained during the previous stable determination section data fR fRAVE (k-1)
Less than. That is, the condition is that the following expression (7) is satisfied. fRAVE (k) <fRAVE (k-1) (7)

[0059] (3) Time SDT stability determination section is a condition that the longer than the previous time. (1) (2) above
A relative speed correction value detection routine is executed based on the condition (3).

In FIG . 7, in the relative speed correction value detection routine, in step S40, a state of determining a stable state of the relative speed data fv and the distance data fR with the vehicle 1 in FIG. The relative speed correction value detection unit 9 in the MPU 9 shown in FIG.
d sets the status of the stability determination state flag SDF to “0,
It is determined by any one bit of "1". When the stability determination state flag SDF is “0” (No), the determination of the stable state is not being performed, and therefore, in step S41, the maximum value fVMAX of the relative speed data fv in the stability determination section is initialized as step S41. And the minimum value fVMIN are respectively initialized to the peak frequency "fa-fb".

[0061] Further, the maximum value fRMAX and minimum value fRMIN distance data fR in stability determination section in step S42
Are initially set to the respective peak frequencies “fa + fb”. Then, in order to start the stability determination, step S43 is performed.
Thereby, the stability determination state flag SDF is set to "1", and the process returns to the main routine shown in FIG.

[0062] On the other hand, when the stability determination condition flag SDF in step S40 is "1" (Yes), already because the stability determination being performed, set the peak frequency "fa-fb" of the relative speed data fv by step S44 Then, the peak frequency “fa + fb” is set in the distance data fR.

[0063] Here, as shown in FIG. 6, within a preset stability determination time, the maximum value of the relative velocity data fv FVMA
If the difference between X and the minimum value fVMIN and the difference between the maximum value fRMAX and the minimum value fRMIN of the distance data fR are within a predetermined fixed value width, the stability is determined.

For this reason, the relative speed data fv is compared with the maximum value fVMAX in step S45, and if the relative speed data fv is larger than the maximum value fVMAX (Yes), step S45 is performed.
At 46, the relative speed data fv is set to the maximum value fVMAX,
The maximum value fVMAX of the relative speed data fv is updated, and the process proceeds to step S46.

[0065] On the other hand, the relative velocity data f at step S45
If v is equal to or less than the maximum value fVMAX (No), step S4
7, the relative speed data fv is compared with the minimum value fVMIN, and when the relative speed data fv is smaller than the minimum value fVMIN (Y
es) In step S48, the relative speed data fv is set to the minimum value fVMIN, and the minimum value fVMI of the relative speed data fv is set.
N is updated, and the process proceeds to step S49. On the other hand, step S
If the relative speed data fv is equal to or greater than the minimum value fVMIN at 47 (No), the process proceeds to step S49 without updating both the maximum value fVMAX and the minimum value fVMIN.

In step S49, the relative speed data fv
Is compared with a stability reference width fVSW for determining the stability of the difference between the maximum value fVMAX and the minimum value fVMIN.
If the difference between X and the minimum value fVMIN is greater than or equal to the stability reference width fVSW (No), it indicates that the relative speed data fv has deviated from the stability reference width fVSW, and the stability determination state flag SDF is set to "0" in step S58. Is cleared, the stability determination state is cancelled, and the routine returns to the main routine.

[0067] On the other hand, if the difference is stable reference width fVSW smaller than the maximum value fVMAX and minimum fVMIN in step S49 (Yes), k-th average value fVAVE relative velocity data fv stability determination in a section in step S50 ( k) is calculated by the following equation (8) and stored in the average value fVAVE. fVAVE (k) = {(k-1) fVAVE (k-1) + fv} (8)

In order to check the stability of the distance data fR in the same manner as in the case of the relative speed data fv, step S51 is performed.
When the distance data fR is larger than the maximum value fRMAX by comparing the distance data fR with the maximum value fRMAX (Yes), the distance data fR is set to the maximum value fRMAX in step S53, updated, and the process proceeds to step S55.

[0069] On the other hand, when the distance data fR is equal to or less than the maximum value fRMAX in step S51 (No), the distance data fR compared with the minimum value fRMIN in step S52, the minimum value fR
If MIN is small (Yes), the distance data fR is set to the minimum value fRMIN in step S54, and the minimum value fRMIN is set.
Is updated, and the process proceeds to step S55. On the other hand, step S52
And the distance data fR is greater than or equal to the minimum value fRMIN (N
o), the process proceeds to step S55 without updating both the maximum value fRMAX and the minimum value fRMIN.

In step S55, the difference between the maximum value fRMAX and the minimum value fRMIN is determined by the stability reference width fVSW for stability determination.
If the difference between the maximum value fRMAX and the minimum value fRMIN is equal to or greater than the stability reference width fVSW (No), it indicates that the distance data fR has deviated from the stability reference width fVSW, and therefore the stability determination flag is set in step S58. The SDF is cleared to "0", the stability determination state is canceled, and the process returns to the main routine.

[0071] On the other hand, in step S55, the maximum value fRMAX
Is smaller than the stability reference width fVSW (Yes), the k-th average value fVAVE (k) of the distance data fR within the stability determination section is obtained by the following equation (9) in step S56. , And the average value fVAVE. fVAVE (k) = {(k-1) fVAVE (k-1) + fv} / k (9)

In step S57, step S56
When the average value fVAVE of the distance data fR obtained in the above is compared with the average value fVAVELT of the distance data fR in the previous stability determination section, if the average value fVAVE is large (No), the distance to the vehicle 1 as an obstacle is reduced. , Indicating that the stability determination flag SDF is cleared to "0" in step S58, the stability determination state is cancelled, and the process returns to the main routine. On the other hand, if the average value fVAVE is smaller than the average value fVAVELT in step S57 (Yes), it is checked in step S59 whether a predetermined stability determination time has elapsed.

In step S59, the stability determination count SDCNT is compared with a predetermined stability determination time SDT.
If the stability determination count SDCNT is small (Yes),
In step S61, the stability determination count SDCNT is incremented, and the process returns to the main routine. On the other hand, step S
At 59, the stability judgment count SDCNT is set to the stability judgment time SDT
If this is the case (No), it indicates that the stability determination time has elapsed, and in step S60, the stability determination count SDCNT is cleared to "0".

In step S62, the average value fVAVE of the distance data fR in the stability determination section is stored as the average value fVAVELT of the distance data fR in the previous stability determination section, and is used in the stability determination conditions in the next stability determination section. To update for.
Further, in step S63, the difference between the maximum value fVMAX and the minimum value fVMIN of the relative speed data fv in the stability determination section is stored in the stability reference width fVSW of the stability determination and used in the next stability determination condition in the stability determination section. To be stored. In step S66, a time obtained by extending the stability determination time SDT by the time T is stored in the stability determination time SDT, and is updated for use in the next stability determination condition in the stability determination section.

In step S64, the average value fVAVE of the relative speed data fv and the upper limit value fV0F of the relative speed correction value are set.
Compared with F, the average value fVAVE is compared with the upper limit value fV0FF. If the average value fVAVE is small (Yes), the average of the relative speed data fv in the stability determination section is added to the relative speed correction value αV in step S65. Store the value fVAVE and return to the main routine.

[0076] On the other hand, as the average fVAVE often higher than the upper limit value fV0FF (No), it is difficult to correct the deviation of the peak frequency corresponding to the peak frequency and a down section corresponding to the up section of the triangular wave in step S64, step S67
Determines that the operation of the radar head 4 and the like is abnormal,
An alarm signal is output to the alarm 12, and an alarm is issued when the alarm 12 is lit. After this process, the process ends without returning to the main routine.

[0077]

As is apparent from the above description, according to the method for correcting the relative velocity in the on-vehicle radar device according to the first, second and sixth aspects of the present invention, a constant setting in the frequency spectrum extracted from the reflected wave signal is provided. Detecting a difference between the peak frequencies of the beat signals corresponding to the ascending section and the descending section of the triangular wave signal in the section, the difference between the maximum value and the minimum value of the difference being smaller than a preset value, and the sum of the peak frequencies; If the difference between the maximum value and the minimum value is smaller than a preset value, the peak frequency difference value is sequentially averaged, and the average value obtained at the end of the set section sets the upper limit of the relative speed correction value. An average value that falls below is detected as a relative speed correction value.

As a result, the deviation of the peak frequency of the reflected wave generated due to the design and manufacturing error of the transmission / reception system for obtaining the beat signal, the ambient temperature and the secular change is reliably corrected, and the relative speed is corrected with high accuracy. become able to.

[0079] According to the relative velocity correction method in the in-vehicle radar device according to claim 3-5, wherein, the next time the difference between the maximum and minimum values of the difference between the peak frequency of the set interval, the distance and the relative velocity It is used for the stability determination condition in the unit period, the average value of the sum of the peak frequencies in the set section is used for the next stability determination condition, and the time exceeding the stability determination time in the set section is used for the next stability determination. It is used as the discrimination time.

[0080] As a result, sequentially become severe condition determination of the correction value detection from the next, the correction value of the relative speed is set to the latest value, it becomes possible relative velocity correction with higher accuracy.

[Brief description of the drawings]

FIG. 1 shows a relative speed compensation in a vehicle-mounted radar device according to the present invention.
It is a block diagram showing composition in an embodiment of a right method .

FIG. 2 is a block diagram showing a detailed configuration of a radar head in FIG.

FIG. 3 is a flowchart showing a processing procedure for predicting and determining a collision in the embodiment;

FIG. 4 is a diagram illustrating a processing state of a collision prediction determination in the embodiment.

FIG. 5 is a flowchart illustrating a processing procedure for detecting a relative speed correction value in the embodiment.

FIG. 6 is a diagram illustrating a process of detecting a relative speed correction value in the embodiment.

FIG. 7 is a flowchart showing a processing procedure for detecting a relative speed correction value in another example for obtaining high accuracy in the embodiment.

FIG. 8 is a diagram for explaining calculation of a distance from a beat signal to an obstacle and a relative speed in a conventional example.

FIG. 9 is a diagram showing a difference frequency versus a relative speed in a conventional example.

[Explanation of symbols]

 Reference Signs List 1 automobile 2 transmission antenna 3 reception antenna 4 radar head 4a voltage controlled oscillator (VCO) 4b directional coupler 4c mixer 8 triangular wave signal generator 9 MPU 9a spectrum extraction unit 9b peak frequency detection unit 9c distance / relative speed detection unit 9d relative Speed correction value detection unit 9e Collision prediction unit 10 Drive circuit 11 Brake device 12 Alarm

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01S 7/00-7/42 G01S 13/00-13/95

Claims (6)

(57) [Claims] 1. An on-vehicle radar apparatus for transmitting an FM modulated wave based on a triangular wave signal to a moving object to be measured and correcting a relative speed when measuring a distance to the moving object and a relative speed from the reflected wave. In the relative velocity correction method, a frequency spectrum of the reflected wave signal is extracted, a difference between peak frequencies of beat signals corresponding to an ascending section and a descending section of the triangular wave signal in a fixed setting section is detected, and a maximum value of the difference is detected. And the difference between the triangular signal and the minimum value.
Sum of the peak frequencies of the beat signal corresponding to the interval and the down section
And obtain the difference between the maximum and minimum values of this sum.
If the value of this difference is smaller than a preset value ,
The vehicle-mounted vehicle according to claim 1, wherein the average value of the difference between the peak frequencies is sequentially calculated, and an average value obtained at the end of the set section is lower than an upper limit of the relative speed correction value as a relative speed correction value. A relative velocity correction method for a radar device. 2. The relative velocity correction method for an on-vehicle radar device according to claim 1, wherein the frequency spectrum is obtained by FFT processing. 3. The relative velocity correction method for an in-vehicle radar device according to claim 1, wherein when a setting condition of a relative speed correction value is satisfied in a set section, a value of a peak frequency difference value in the set section is set. A relative speed correction method for a vehicle-mounted radar device, wherein a difference between a maximum value and a minimum value is used as a stability determination condition in a next unit period of a distance and a relative speed. 4. The relative velocity correction method for an on-vehicle radar device according to claim 1, wherein when a setting condition of a relative velocity correction value is satisfied in a set section, a value of a sum of peak frequencies in the set section is set. The average value is used as a stability determination condition in the next unit period of the distance and the relative speed, and the average value is used in a vehicle-mounted radar device .
Speed correction method . 5. The relative speed correction method for an in-vehicle radar device according to claim 1, wherein, when a setting condition of a relative speed correction value is satisfied in a set section, a unit of a distance and a relative speed in the set section. A relative speed correction method for a vehicle-mounted radar device, wherein a time exceeding a stability determination time in a period is used as a next stability determination time. 6. The relative speed correction method for an on-vehicle radar device according to claim 1, wherein the abnormality notification is performed when an average value obtained at the end of the set section exceeds an upper limit of the correction value of the relative speed. A method for correcting a relative speed in a vehicle-mounted radar device.