JP2006275748A - Detecting device for value of axis misalignment of radar - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detecting device for value of axis misalignment of radars capable of measuring correctly the value of axis misalignment even during transition from line travelling to curve travelling, in measurement of value of axis misalignment in the horizontal direction of radar based on the distribution of stationary targets. <P>SOLUTION: By holding time-sequentially the flags showing the data of two-dimensional-like distribution of detected stationary targets and whether traveling is in line cruise or curve cruise from the present to a predetermined time (steps 1002 to 1018), the distribution data and flags until a predetermined time are held as T_Map(4) and T_Flag(4). Only when line travelling is discriminated for any time at the present and before a predetermined time (step 1020), the distribution data T_Map (4) before a predetermined time is integrated to A_Map (step 1022), and then the axis misalignment value is calculated based on the integrated value A_Map (step 1026). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus for determining a horizontal axis misalignment amount of a radar mounted on a vehicle.

  The in-vehicle radar detects the azimuth angle θ of the target by electronically or mechanically scanning the emission direction of the radio wave in addition to the distance R to the target and the relative velocity V of the target, and X = R · sin θ Can detect the lateral position X of the target. By detecting the lateral position X, it becomes possible to control the inter-vehicle distance based on the distance and relative speed of the vehicle traveling in front of the own vehicle.

  After such an in-vehicle radar is installed in a vehicle, if a horizontal axis deviation occurs due to an external force applied for some reason, a deviation occurs between the traveling direction of the vehicle recognized by the radar and the actual traveling direction of the vehicle. For this reason, the azimuth angle θ of the target detected by the radar deviates from the actual azimuth angle, and the position of the target to be subject to the inter-vehicle control is erroneously recognized.

  In Patent Document 1 below, the detection positions of a large number of stationary objects such as guardrails provided on both sides of a road are distributed along virtual straight lines on the left and right of the road, A technique is disclosed in which a virtual straight line is obtained from the recognized distribution of the position of an object by the least square method, and the inclination of the virtual straight line is used as the horizontal axis deviation amount.

  When a vehicle equipped with radar is traveling on a curve, the direction in which stationary objects such as guardrails in front of the vehicle are aligned is inclined with respect to the traveling direction of the vehicle, causing misrecognition of the amount of misalignment. become. In order to avoid this, Patent Document 1 discloses detecting whether or not the vehicle is traveling straight based on the output of the yaw rate sensor, and detecting the axis deviation angle θ only when traveling straight. ing.

  However, as shown in FIG. 1, immediately before the vehicle 20 shifts from straight running to curved running, the virtual output obtained from the distribution of the stationary object 22 in front of the sensor 20 shows that the output of the sensor shows straight running. A situation occurs in which the straight line 24 is inclined with respect to the traveling direction 26 of the vehicle, which causes a problem of erroneously recognizing the amount of axis deviation.

JP 2001-166051 A

  Accordingly, an object of the present invention is to provide an axis deviation amount determination device capable of accurately determining an axis deviation amount.

According to the present invention, the holding means for holding the distribution data of the predetermined time by holding the data of the two-dimensional distribution of the detected stationary target in time series from the present to the predetermined time, and the holding An integration unit that integrates distribution data before a predetermined time held by the unit, and an axis deviation amount calculation unit that calculates an axis deviation amount based on the accumulated distribution data. Provided is a radar axis deviation determination device that multiplies the distribution data before a predetermined time by a predetermined ratio and accumulates when the turning radius of the vehicle on which the radar is mounted is equal to or less than a predetermined value.
According to the present invention, the holding means for holding the data of the distribution of the detected stationary target in a time series from the present to a predetermined time before, and the integrating means for integrating the distribution data held by the holding means before the predetermined time And an axis deviation amount calculating means for calculating an axis deviation amount based on the accumulated distribution data, wherein the integrating means is configured such that the turning radius of the vehicle on which the radar is mounted is a predetermined value at present or before the predetermined time. A radar axis misalignment determining apparatus that does not use the distribution data before the predetermined time for the integration when it is the following is also provided.

  In the above configuration, the integrating means normally integrates the distribution data obtained before a predetermined time, and the axis deviation amount is calculated based on the integrating data. When the vehicle carrying the radar reaches the curve and the turning radius falls below a predetermined value, the distribution data before a predetermined time is multiplied by a predetermined ratio, preferably zero. The contribution of the distribution data from before time becomes small or zero, and the problem described with reference to FIG. 1 is solved.

  On the other hand, immediately after turning the curve and moving straight, the distribution data before the predetermined time is the distribution data during the curve traveling, and if this is integrated as it is, an inaccurate axis deviation amount can be obtained. It will be. Thus, this problem can be avoided by adopting a configuration in which the distribution data is multiplied by a predetermined ratio, preferably zero, when the turning radius is equal to or less than a predetermined value “currently or before a predetermined time”.

  FIG. 2 shows a configuration of an inter-vehicle control radar as an example of a radar to which the present invention is applied.

  In FIG. 2, the ECU 10 calculates the turning radius of the own vehicle based on the signal from the yaw rate sensor 12 and the signal from the vehicle speed sensor 14, and sends it to the FM-CW radar 16 together with the vehicle speed data. The turning radius can also be calculated by using the output of a steering sensor (not shown) instead of the output of the yaw rate sensor 12. The FM-CW radar 16 emits a millimeter-wave band radio wave that is frequency-modulated with a triangular wave to the front of the host vehicle, analyzes the reflected wave, and thereby the distance from the target existing ahead and the relative velocity of the target. Is calculated. As described above, the FM-CW radar 16 also scans the emission direction of the radio wave, calculates the lateral position of the target based on the power distribution of the reflected wave at that time, and calculates the ECU 10 together with the distance and relative velocity data. Send to. Based on these data, the ECU 10 generates and outputs a control signal for maintaining a constant distance from the vehicle traveling ahead.

  In one embodiment of the present invention, in order to calculate the horizontal axis misalignment amount, the ECU 10 first selects a target whose relative speed substantially matches the vehicle speed among the targets detected by the FM-CW radar 16 as a stationary target. As specified. Then, the horizontal axis is the horizontal position of the stationary target and the vertical axis is the distance of the stationary target. The two-dimensional plane is separated by the horizontal axis and equally spaced straight lines parallel to the vertical axis and enters each divided area. Distribution data as shown in FIG. 3 is created by counting the number of stationary targets. Hereinafter, this distribution data is referred to as Temp_Map or T_Map. The example shown in FIG. 3 is obtained by adding 10 times the data of a stationary target obtained at a cycle of 100 msec.

  In order to create such T_Map at a constant cycle (for example, 100 sec × 10 = 1 cycle) and hold T_Map for a predetermined time before (for example, 4 sec), T_Map from the present to the predetermined time before can be determined by, for example, T_Map (I) (I = 0, 1... 4) is held in time series. Here, T_Map (I) means, for example, T_Map before I seconds.

  While it is determined that the vehicle's turning radius is larger than a predetermined value (for example, 2000 m) and the vehicle is traveling in a straight line, the distribution data (for example, T_Map (4)) before the predetermined time is integrated to accumulate in the horizontal direction. Obtain distribution data required for calculation of the amount of misalignment. The integrated distribution data is hereinafter referred to as A_Map. In calculating the horizontal axis deviation amount from A_Map, for example, as described in Patent Document 1, the inclination of the imaginary straight line obtained by the least square method is used as the axis deviation amount.

  When it is determined that the turning radius of the host vehicle is smaller than the predetermined value and the vehicle has entered the curve, the integration of T_Map (4) to A_Map is immediately stopped. As a result, the distribution data from a predetermined time before entering the curve is excluded from the integration to A_Map, and the accuracy of the axis deviation amount can be improved.

  On the other hand, immediately after the transition from the curve travel to the straight travel, the distribution data before the predetermined time includes an inclination due to the curve. Therefore, by holding a flag T_Flag (I) indicating whether or not the turning radius is greater than or equal to a predetermined value in a time series together with T_Map (I), it is determined whether or not the distribution data before a predetermined time is a straight line running. Holds the information shown. When T_Map (4) is integrated into A_Map, this problem can be avoided if the integration is performed only when the vehicle is running in a straight line both at the present time and a predetermined time ago.

FIG. 4 is a flowchart showing a first example of the axis deviation amount determination process realized by the program of the ECU 10. The process shown in FIG. 4 is started at a constant cycle, for example, at a cycle of 1 second. First, it is determined whether the speed V of the vehicle on which the radar is mounted exceeds a predetermined value V ₀ (for example, 36 km / h), and this process is executed only when the vehicle speed V is equal to or higher than V ₀ .

  In steps 1002, 1004, 1006 and 1008, in order to update the past distribution data T_Map (I) and the flag T_Flag (I) (I = 1, 2,... 4) stored in time series, I = 4 For 3, 2, 1, the data of T_Map (I-1) is moved to T_Map (I), and the value of T_Flag (I-1) is moved to T_Flag (I).

Next, among the targets detected by the FM-CW radar 16, those whose relative speed substantially matches the speed of the own vehicle are identified as stationary targets (step 1010), and the two-dimensional distribution thereof is T_Map. It is stored in (0) (step 1012). As described above, for example, the distribution may be determined at a period of 100 msec, and 10 times of the distribution may be added to obtain T_Map (0). In step 1014, the absolute value of the rotational radius R of the vehicle is compared with a predetermined value R ₀ (e.g., 2000 m) that is determined from the output of the yaw preparative rate sensor 12, when R is R ₀ or more a t_flag (0) Zero (step 1016), T_Flag (0) is set to 1 when R is less than or equal to R ₀ (step 1018). Then, it is determined whether T_Flag (0) or T_Flag (4) is zero (step 1020). If both are zero, T_Map (4) is added to A_Map (step 1022), and at least If one is not zero, this process is bypassed. Finally, in step 1024, it is determined whether or not there are 10 or more regions where the value of the axis deviation value exceeds 100 in A_Map. If the calculation condition is not satisfied, the processing returns to step 1000, When is established, the amount of axis deviation is calculated from A_Map (step 1026), and the value of A_Map is cleared (step 1028).
FIG. 5 shows an example of A_Map. For example, when four or more regions where the value exceeds 150 are arranged vertically (in the distance direction), the straight line for each vertical area is calculated by the least square method and approximated by 180 / π to obtain the inclination. Ask. The angle formed between the inclination and the traveling direction is the amount of axial deviation. That is, assuming that the horizontal position of four regions (enclosed by squares in the figure) is x _i (i = 1 to 4) and the vertical direction value is y _i , the axis deviation angle θ is expressed by the equation θ = (4 * Σx _i y _i −Σy _i ) / (4 * Σx _i ² − (Σx _i ) ² ) * (180 / π)
Is calculated by For example, when the calculated axis deviation amount is 5 ° or more, it is determined to be abnormal, and when it is less than 5 °, it is determined to be normal.

  FIG. 6 is a flowchart showing a second example of the axis deviation amount calculation processing of the present invention. A difference from the example of FIG. 4 is that when T_Flag (0) or T_Flag (4) is 1, a value obtained by multiplying T_Map (4) by a predetermined ratio, for example, 0.5 is added to A_Map (step 1023). Is a point. When a vehicle equipped with a radar travels on a general road, it is difficult to obtain data at the time of straight traveling. Thus, the amount of axis deviation can be calculated at an early stage.

  Instead of using the distribution data (steps 1022 and 1023) used for integration as the distribution data before the fixed time of “predetermined time” as described above, this is changed according to the vehicle speed, so that “predetermined distance” ahead is obtained. Data may be integrated. Further, the aforementioned “predetermined ratio” may be changed according to the turning radius of the vehicle.

It is a figure for demonstrating the subject of this invention. It is a block diagram which shows the structure of an example of the radar to which this invention is applied. It is a figure which shows an example of T_Map. It is a flowchart of an example of the axial deviation | shift amount determination process of this invention. It is a figure which shows an example of A_Map. It is a flowchart of the other example of the axial deviation amount determination process of this invention.

Claims (6)

Holding means for holding data of the distribution of the detected stationary target in a time series from the present to a predetermined time;
Integration means for integrating distribution data of a predetermined time held by the holding means;
An axis deviation amount calculating means for calculating an axis deviation amount based on the accumulated distribution data;
The integrating means determines the amount of radar axis deviation to be integrated by multiplying the distribution data before the predetermined time by a predetermined ratio when the turning radius of the vehicle on which the radar is mounted is equal to or less than a predetermined value at the present or the predetermined time before. apparatus.   2. The radar axis deviation determination apparatus according to claim 1, wherein the predetermined ratio is zero.   2. The radar axis deviation determining apparatus according to claim 1, wherein the predetermined ratio is changed according to a turning radius of the vehicle. Holding means for holding data of the distribution of the detected stationary target in a time series from the present to a predetermined time;
Integration means for integrating distribution data of a predetermined time held by the holding means;
An axis deviation amount calculating means for calculating an axis deviation amount based on the accumulated distribution data;
The integrating means is a radar axis deviation determining device that does not use the distribution data before the predetermined time for the integration when the turning radius of the vehicle on which the radar is mounted is equal to or less than a predetermined value at present or before the predetermined time.   The radar axis deviation determination apparatus according to any one of claims 1 to 4, wherein the predetermined time is changed according to a speed of the vehicle.   The radar axis deviation according to any one of claims 1 to 5, wherein when the vehicle speed is equal to or lower than a predetermined value, updating of distribution data held by the holding means and accumulation of distribution data by the integrating means are stopped. Quantity determination device.

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