JPH09159759A - Instrument for measuring distance between vehicles - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring device capable of exactly distinguishing a running vehicle from a stationary object. SOLUTION: When relative velocities, Vref are calculated from a plurality of distance signals d0 , d1 ,... dr adjacent to each other, the calculations are performed a plurality of times by shifting the start points of the distance signals for each sample. Only if all the relative velocities Vref0 , Vref1 ..., obtained with a plurality of operations satisfy -100<=Vref <=0.7.Vs (Vs: vehicle velocity), the captured object is judged as an antecedent vehicle and a distance signal dr is output as a signal of distance between vehicles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inter-vehicle distance measuring device for identifying a preceding vehicle and a stopped object in front of the vehicle and outputting a signal indicating that the vehicle is the inter-vehicle distance or the stopped object. The present invention relates to a preferred inter-vehicle distance measuring device applied to a vehicle traveling control device or the like that controls the vehicle to automatically follow a preceding vehicle.

[0002]

2. Description of the Related Art In recent years, with the spread of a constant speed traveling device for traveling a vehicle at a constant set speed, when the constant speed traveling device is operated for the purpose of preventing a rear-end collision with a preceding vehicle and improving driving operability. Various devices have been proposed that control the traveling speed of the host vehicle so that the host vehicle automatically follows the preceding vehicle while maintaining a safe inter-vehicle distance.

This type of vehicle travel control device is equipped with a radar device (inter-vehicle distance measuring device) for measuring the distance to an object in front of the vehicle in the traveling direction. It is extremely important for the automatic follow-up control to accurately identify whether the preceding object is the preceding vehicle that is the follow-up target or is merely a stopped object. In particular, when traveling on a curved road, the radar device may or may not capture the preceding vehicle, and if a stationary object is mistakenly recognized as the preceding vehicle, unnecessary deceleration may occur, or conversely When the vehicle is mistakenly recognized as a stationary object, it becomes impossible to maintain the optimum safe inter-vehicle distance.

Therefore, for example, Japanese Patent Laid-Open No. 60-121,1
In the vehicle traveling control device disclosed in Japanese Patent No. 31, the distance signal measured by the radar device is an inter-vehicle distance signal with a preceding vehicle traveling in front of the host vehicle, or a roadside corner reflector or a guide sign. Whether the signal is a distance signal to the stationary object of is identified by the following method.

That is, when the radar device captures the roadside reflector while the host vehicle is traveling at the speed Vs, the distance signal output from the radar device has a waveform shown in FIG. . In FIG. 4, the vehicle 5 is shown in FIG.
As shown in FIG. 5, the distance signal when three reflectors 7 on the curved road side are sequentially captured is illustrated. In this figure, before the radar device captures the roadside reflector 7, a distance indefinite signal is output (indicated by “A” in FIG. 4), but when the roadside reflector 7 is captured, that is, when the distance is determined, the moment The distance signal B of the
Since the distance to the roadside reflector 7 is gradually shortened as the vehicle travels, the distance signal B → C corresponding thereto is output.

Since the distance signal detected by the radar device is read at a constant sampling time T, the slope portion of the distance signal B → C is enlarged as shown in FIG. In FIG. 5, the distance signal at the instant t ₀ when the roadside reflector 7 is captured is d ₀ , and the distance signal at t ₈ is d ₈ when the _eighth sampling is performed from this time t ₀ . The relative velocity V _ref between the vehicle 5 and the roadside reflector 7 in this _{case, V ref = (d 8 -d} 0) / (t 8 -t 0) becomes ≒ -Vs.

Here, at least k times the vehicle speed (0 <k <1)
An object having a relative velocity of is determined to be a stationary object, that is, when | V _ref |> k · Vs (1), it is determined that the radar device has captured the roadside reflector 7. On the other hand, when the expression (1) is not satisfied, it is determined that the preceding vehicle 6 traveling in front of the host vehicle 5 is captured.

[0008]

However, in the above-described conventional inter-vehicle distance measuring device, when capturing one roadside reflector one by one, it does not cause any problem, but it is different when one roadside reflector 7 is captured. When the measurement is performed such that the roadside reflector 7 is captured, or a plurality of roadside reflectors 7 and 7 are simultaneously captured, the obtained distance signal has an ideal waveform with a substantially constant slope as shown in FIG. It rarely happens.

That is, as shown in FIG. 6, a "blurring" X of a waveform, which is considered to be caused by the detection accuracy of the inter-vehicle distance measuring device, and a distance generated when different roadside reflectors are continuously detected without a time interval. In many cases, "jump" Y of the signal or "jump" of the distance signal that occurs when a plurality of roadside reflectors are alternately detected at the same time as shown in FIGS. 7 and 8.

When the relative velocity V _ref is calculated from the distance signals at two points using such a waveform, there are many cases where the formula (1) is not satisfied even if the roadside reflector is captured, and it is actually captured. It may not be possible to accurately recognize whether the existing object is the preceding vehicle or the stationary object. For this reason, if such an inter-vehicle distance measuring device is used for automatic follow-up control, a stopped object may be mistakenly recognized as a preceding vehicle, and unnecessary deceleration may occur to prevent smooth follow-up travel. Even if the average value is obtained from the following several distance signals by using the least square method to obtain the relative velocity V _ref , this problem cannot be solved.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide an inter-vehicle distance measuring device capable of reliably discriminating a preceding vehicle and a stopped object.

[0012]

In order to achieve the above object, in the inter-vehicle distance measuring apparatus of the present invention, an object in front of the host vehicle is a preceding vehicle traveling in front of the host vehicle or a stopped object. A vehicle distance measuring device that determines whether or not the vehicle is a preceding vehicle and outputs an inter-vehicle distance when the vehicle is a stopped object and outputs an indefinite distance signal when the vehicle is a stationary object. A distance detecting means for outputting a distance signal, a vehicle speed detecting means for detecting the speed of the own vehicle and outputting a vehicle speed signal, and a plurality of adjacent distance signals from the plurality of distance signals detected by the distance detecting means. A plurality of groups are extracted while sequentially shifting individual distance signals, and relative speed calculation means for calculating the relative speed between the own vehicle and the object in each distance signal group, and based on the vehicle speed signal from the vehicle speed detection means. The preceding vehicle And when setting the reference range of the relative velocity to be determined, the relative speed of each distance signal group calculated by said relative velocity calculation means is within all the reference range,
When the distance signal detected by the distance detecting means is determined to be the inter-vehicle distance to the preceding vehicle and is output, and even if any one of the relative speeds of the distance signal groups is not within the reference range, Stop object determining means for determining the distance signal detected by the distance detecting means as a distance signal to a stop object and outputting a distance indefinite signal.

In the present invention, when the object captured by the distance detecting means is the preceding vehicle, first, there is no jump in the distance signal, and second, the relative speed is higher than that when the object is a stationary object. It's small. In other words, jumping occurs in the distance signal when different stopped objects are continuously detected without a time interval or when a plurality of stopped objects are alternately detected at the same time, and the preceding vehicle or the same stopped object is detected. , No large jump occurs in the adjacent distance signals. Therefore, when there is no jump in the distance signal, the captured object is either the preceding vehicle or the same stopped object. Both of them can be easily identified by the relative speed of the host vehicle. . That is, when the vehicle is a preceding vehicle, the relative speed with respect to the own vehicle becomes small, and when the object is a stopped object, the relative speed with respect to the own vehicle becomes approximately the traveling speed of the own vehicle.

Based on such knowledge, the inter-vehicle distance measuring apparatus of the present invention extracts a plurality of groups while sequentially shifting a plurality of adjacent distance signals from the plurality of distance signals detected by the distance detecting means. , The relative velocities of the own vehicle and the object in each distance signal group are calculated, and when all of these relative velocities are within the reference range, the captured object is determined to be the preceding vehicle.

Since a plurality of groups are extracted while sequentially shifting a plurality of distance signals adjacent to each other, and the relative speed between the vehicle and the object in each distance signal group is calculated, when there is a jump in the distance signals. , Its relative speed will fall outside the reference range. This makes it possible to identify whether or not there is a jump in the distance signal. Further, by setting the reference range of the relative speed that should be determined as the preceding vehicle based on the vehicle speed signal from the vehicle speed detecting means, it is possible to identify whether the captured object is the preceding vehicle or the same stopped object.

When any one of the relative velocities of each distance signal group is not within the reference range, the distance signal has a jump, and therefore the captured object is determined to be a stationary object and the distance indefinite signal is determined. Is output.

The distance detecting means according to the present invention detects a distance to an object in front of the host vehicle and outputs a distance signal, and is a radar device using a laser, an ultrasonic wave, or an electric wave, for example.

Further, the vehicle speed detecting means according to the present invention detects the speed of the own vehicle and outputs a vehicle speed signal, and a vehicle speed sensor such as a vehicle speed sensor may be used.

When the relative speed between the host vehicle and the object is calculated by the relative speed calculation means according to the present invention, the number of distance signals extracted by the distance detection means is not limited as long as they are adjacent to each other. However, if the number of extracted distance signals is small, the number of distance signal groups is large, so the calculation time is long, and if the number of extracted distance signals is large, the detection accuracy of distance signal jumps is reduced. It is desirable to set an appropriate number in relation to the set value of the reference range. Further, it is preferable that the number of groups extracted by sequentially shifting the plurality of distance signals adjacent to each other includes at least all the distance signals detected by the distance detecting means.

In the stationary object determining means according to the present invention,
The reference range of the relative speed to be determined as the preceding vehicle is set on the basis of the vehicle speed signal of the own vehicle detected by the vehicle speed detecting means, and this is a reference as to whether the captured object is the preceding vehicle or the stopped object.

In the stationary object judging means according to the present invention,
When the difference between the adjacent distance signals in each of the distance signal groups is equal to or more than a predetermined value, the distance signal detected by the distance detecting means is determined as a distance signal to the stationary object and the distance is determined. An indefinite signal can also be output.

In the inter-vehicle distance measuring apparatus of the present invention, the distance detecting means detects the distance to the object in front of the host vehicle and outputs the distance signal. The object captured by the distance detecting means is the preceding vehicle. In some cases or in the case of the same stationary object, it can be said that a large jump does not occur in adjacent distance signals. In other words, when different stopping objects are continuously detected without a time interval, or when a plurality of stopping objects are alternately detected at the same time, a jump occurs in the distance signal. The difference between adjacent distance signals in the signal group is calculated, and if the difference is equal to or more than a predetermined value, it is determined that the distance signal jumps, and the captured object is recognized as a stationary object. To do. By adding this function, since it may be recognized as a stationary object without calculating the relative speed, the recognition processing speed can be increased.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an inter-vehicle distance measuring apparatus according to an embodiment of the present invention. As shown in FIG. 1, the inter-vehicle distance measuring apparatus according to the present embodiment includes distance detecting means 1 and vehicle speed detecting means 2. , The relative speed calculating means 3 and the stationary object determining means 4, and can be applied as, for example, an inter-vehicle distance measuring device of an automatic tracking device.

The distance detecting means 1 detects a distance to an object in front of the host vehicle and outputs a distance signal. The distance detecting means 1 can be constituted by, for example, a radar device using a laser, an ultrasonic wave, or an electric wave. For example, it is mounted on the front surface of an automobile so that the object can be easily captured. The distance signal detected by the distance detecting means 1 is sent to the relative speed calculating means 3, where it is temporarily stored and used for calculating the relative speed.

Further, the vehicle speed detecting means 2 detects the speed of the own vehicle and outputs a vehicle speed signal, and a vehicle speed sensor such as a vehicle speed sensor may be used. The vehicle speed signal detected by the vehicle speed detecting means 2 is sent to the stationary object determining means 4, where it is temporarily stored and used to set the reference range of the relative speed.

The relative velocity calculation means 3 extracts a plurality of groups from the plurality of distance signals detected by the distance detection means 1 while sequentially shifting a plurality of distance signals adjacent to each other, and extracts a plurality of groups in each distance signal group. The hardware calculates the relative speed between the vehicle and the object, and its hardware includes an input port for inputting the distance signal from the distance detecting means 1, a RAM for temporarily storing the distance signal input from the distance detecting means 1, RO storing a program for extracting a plurality of distance signal groups from this distance signal and a relative velocity calculation program
M, a CPU that performs actual calculation, and an output port that outputs the calculation result to the stationary object determination means 4.

The stationary object determining means 4 mainly has two functions. That is, first, based on the vehicle speed signal from the vehicle speed detecting means 2, the reference range of the relative speed to be determined as the preceding vehicle is set. Secondly, when all the relative speeds of the respective distance signal groups calculated by the relative speed calculating means 3 are within the reference range, the distance signal detected by the distance detecting means 1 is determined as the inter-vehicle distance to the preceding vehicle. When any one of the relative velocities of the respective distance signal groups is not within the reference range, the distance signal detected by the distance detecting means 1 is determined to be the distance signal to the stationary object and the distance is indefinite. Output a signal. The hardware includes an input port for inputting a vehicle speed signal from the vehicle speed detecting means 2 and a relative speed from the relative speed calculating means 3, a RAM for temporarily storing these information, a reference range setting program, and a relative speed determination. ROM that stores the program, CPU that performs actual setting and judgment calculation,
And an output port for outputting the calculation result to the outside.

In this embodiment, the relative speed calculation means 3 and the stationary object determination means 4 have different configurations, but it is also possible to configure them as a single hardware having both of these means 3, 4. Is.

Next, the operation will be described. 2 is an explanatory diagram of signal processing in the same embodiment, and FIG. 3 is a flow chart showing a signal processing procedure in the same embodiment. In the following description, among the plurality of continuous distance signals detected by the distance detecting means 1 at the sampling interval T, the relative speed calculating means 3 has eight continuous distance signals d ₀ , d ₁ ,
, D ₇ are stored, four distance signals adjacent to each other are extracted from these eight distance signals to form one distance signal group, and the distance signal extraction start points are shifted one by one to obtain five distance signals. The case where the distance signal group is extracted will be described. However, in the inter-vehicle distance measuring device of the present invention, the number of distance signals stored in the relative speed calculating means 3 (8) and the number of extraction of adjacent distance signals used for calculating the relative speed (4).
No.) and the number of distance signal groups (5), which is the number of times the relative speed is calculated, and can be appropriately changed.

As shown in FIGS. 2 and 3, first, the distance signals d ₀ ,
d _1, ..., stores d ₇ to the relative speed calculation unit 3 (step 1). While the distance signal d ₀ is not fixed, that is, when there is no captured object in the distance detecting means 1, the distance detecting means 1
Since the signal of indeterminate distance is received from, the stationary object determination means 4 outputs the indeterminate distance signal to the outside (step 2 →
7).

When the distance signal d ₀ is determined, the stopped object determining means 4 determines whether or not the difference between the adjacent distance signals d ₀ , d ₁ , ..., D ₇ is within a certain value (step 2 →
3). That is, the maximum value and the minimum value of the allowable range of the difference between the distance signals adjacent to each other are set in advance, and before calculating the relative speed, it is determined whether or not the distance signal has a large jump that deviates from the allowable range. . In the illustrated embodiment, the maximum value D _max = 4 m and the minimum value D _min = -4 m of the allowable range are set, and D _min <d ₇ −d ₆ <D _max , ..., D _min <d _{i + 1.}
−d _i <D _max , ..., D _min <d ₁ −d ₀ <D _max (0
.Ltoreq.i.ltoreq.6, i is an integer) is determined (step 3), and if even one does not satisfy the allowable range, the stationary object determination means 4 outputs a distance indefinite signal to the outside (step 7).

In this processing, when the distance detecting means 1 captures a preceding vehicle traveling in front of the host vehicle or captures the same stopped object, the distance detecting means 1 has a large value in the adjacent distance signals. This is based on the fact that there is no jump, and by performing this processing before calculating the relative speed, at least when a jump occurs in the distance signal, that is, when different stopped objects are detected continuously without a time interval, It is possible to identify the case where the stationary objects are detected alternately at the same time. As a result, the captured object can be immediately recognized as a stationary object, and the recognition processing speed can be increased.

In step 3, when all the differences between the adjacent distance signals are within the allowable range, it is considered that the distance signal waveform from the distance detecting means 1 is the ideal case shown in FIG. 4 or 5. In addition to the case where the captured object is the preceding vehicle, the case where the same stopped object is captured is included. Therefore, in order to identify this, first, the relative speed calculation means 3 calculates the relative speed (step 4), and the calculation result is sent to the stopped object determination means 4 so that the stopped object determination means 4 takes precedence. A final decision is made as to whether it is a vehicle or a stationary object (step 5).

The relative velocity V _ref between the vehicle and the captured object in the relative velocity calculation means 3 is determined by four distance signals d _i , d _{i + 1} , d _{i + 2} , d _{i + 3} (0 ≦ i ≦ 4, i is an integer) and is calculated by the method of least squares. In this case, since a total of eight distance signals are used, when extracting one distance signal group consisting of four adjacent distance signals, the distance signal group is constructed by shifting the start points of the distance signals one by one. To do. That is, in the present embodiment, the five distance signal groups [d ₀ , d ₁ , d ₂ ,
d ₃ ], [d ₁ , d ₂ , d ₃ , d ₄ ], [d ₂ , d ₃ ,
d ₄ , d ₅ ], [d ₃ , d ₄ , d ₅ , d ₆ ], [d ₄ ,
[d ₅ , d ₆ , d ₇ ] are extracted, and the relative velocities V _ref0 , V _ref1 , V _ref2 , and V of each of these five distance signal groups are extracted.
_ref3 and V _ref4 are calculated.

The five relative velocities calculated by the relative velocity calculating means 3 in this way are sent to the stationary object determining means 4, which then transfers the vehicle speed detecting means 2 to the stationary object determining means 4. Thresholds (reference ranges) V _max and V _min for determining whether the object is a stationary object based on the vehicle speed Vs of the vehicle
And the five relative velocities V previously calculated.
_{ref0, V ref1, V ref2,} V ref3, V ref4 is determined whether there are any within the reference range (Step 5). In the present embodiment, the maximum value V _max of the reference range is −100 (km / km
h) and the minimum value V _min is 0.7 · Vs (km / h).

Then, the five relative speeds V _ref0 , V _ref1 ,
_Only when V _ref2 , V _ref3 , and V _ref4 are all within the reference range, it is determined that the captured object is the preceding vehicle, and the closest distance signal d ₇ is output to the outside as the inter-vehicle distance (step 6). . Also, the five relative speeds V _ref0 ,
If even one of V _ref1 , V _ref2 , V _ref3 , and V _ref4 is out of the reference range, it is determined that the captured object is a stationary object, and the distance indefinite signal is output to the outside (step 7).

As described above, according to the inter-vehicle distance measuring apparatus of the present embodiment, it is possible to immediately judge the jump of the distance signal and also accurately judge whether the preceding vehicle or the stopped object. . The above-described embodiments are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

[0038]

As described above, according to the present invention, a plurality of groups are extracted while sequentially shifting a plurality of distance signals adjacent to each other, and the relative speed between the vehicle and the object in each distance signal group is calculated. Therefore, it is possible to accurately identify the presence or absence of the jump of the distance signal. Further, by setting the reference range of the relative speed that should be determined as the preceding vehicle based on the vehicle speed signal from the vehicle speed detecting means, it is possible to accurately identify whether the captured object is the preceding vehicle or the same stopped object.

In the present invention, the difference between adjacent distance signals in each distance signal group is calculated before the relative velocity is calculated. If the difference is equal to or more than a predetermined value, the distance signal jumps. Since the captured object is determined to be present and the captured object is recognized as a stationary object, the recognition processing speed is increased.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an inter-vehicle distance measuring apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining signal processing of an inter-vehicle distance measuring apparatus that is an embodiment of the present invention.

FIG. 3 is a flowchart showing a signal processing procedure of an inter-vehicle distance measuring apparatus that is an embodiment of the present invention.

FIG. 4 is a graph showing a waveform of a distance detection signal with respect to time when a stationary object is detected.

FIG. 5 is an enlarged graph showing a waveform of a distance detection signal with respect to time when a stationary object is detected.

FIG. 6 is a graph showing a defect example of a distance detection signal waveform with respect to time when a stationary object is detected.

FIG. 7 is a graph showing a defect example of a distance detection signal waveform with respect to time when a stationary object is detected.

FIG. 8 is a graph showing a defect example of a distance detection signal waveform with respect to time when a stationary object is detected.

FIG. 9 is a schematic diagram showing a detection situation of a front stopped object when traveling on a curved road.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Distance detecting means 2 ... Vehicle speed detecting means 3 ... Relative speed detecting means 4 ... Stopping object judging means 5 ... Own vehicle 6 ... Leading vehicle 7 ... Roadside corner reflector (stopping object)

Claims (2)

[Claims] 1. An object in front of the own vehicle is determined whether it is a preceding vehicle traveling in front of the own vehicle or a stopped object, and if it is a preceding vehicle, the inter-vehicle distance is output and the stopped object is detected. In some cases, it is an inter-vehicle distance measuring device that outputs an indefinite distance signal, and a distance detecting unit that detects a distance to an object in front of the own vehicle and outputs a distance signal, and detects the speed of the own vehicle. From vehicle speed detection means for outputting a vehicle speed signal, and a plurality of distance signals detected by the distance detection means,
Relative speed calculating means for extracting a plurality of groups while sequentially shifting a plurality of distance signals adjacent to each other, and calculating a relative speed between the own vehicle and the object in each distance signal group, and a vehicle speed from the vehicle speed detecting means. If a relative speed reference range to be determined as the preceding vehicle based on a signal is set and the relative speeds of the distance signal groups calculated by the relative speed calculation means are all within the reference range, the distance The distance signal detected by the detection means is judged to be the inter-vehicle distance to the preceding vehicle and is output, and if any one of the relative speeds of the distance signal groups is not within the reference range, the distance is calculated. An inter-vehicle distance measuring device, comprising: a stop object determining means that determines the distance signal detected by the detecting means as a distance signal to a stop object and outputs a distance indefinite signal. 2. The stationary object determining means determines the distance signal detected by the distance detecting means when the difference between adjacent distance signals in each distance signal group is equal to or more than a predetermined value. The vehicle-to-vehicle distance measuring device according to claim 1, wherein the in-vehicle distance measuring device outputs a distance indefinite signal by determining that it is a distance signal to a stationary object.