JP4884929B2 - Vehicle travel control device - Google Patents

Description

  The present invention relates to a travel control device for a vehicle that appropriately gives an alarm or the like when traveling following a preceding vehicle.

In recent years, in vehicles, the front traveling environment is detected by an on-board camera, laser radar device, etc., obstacles and preceding vehicles are recognized from the traveling environment data, the target deceleration of the own vehicle is set, the obstacle A traveling control device that travels while maintaining a constant inter-vehicle distance with respect to a preceding vehicle has been developed and put into practical use. Many of these traveling control devices issue a warning regarding the relationship between the preceding vehicle and the host vehicle. For example, in Japanese Patent Application Laid-Open No. 7-159525, contact prediction is obtained by dividing the detected distance between vehicles at the start of deceleration by the relative speed. The time is calculated, the predicted contact time at the start of the deceleration action is stored for each deceleration, and the predicted contact time of the driver is estimated from the stored predicted contact time at each deceleration action. Then, a technique is disclosed in which a value obtained by multiplying the detected relative speed value by the estimated contact time estimation value is subtracted from the detected inter-vehicle distance value to calculate an estimated inter-vehicle distance, and an alarm is issued when the predicted inter-vehicle distance is shorter than the warning distance. ing.
JP-A-7-159525

  However, in the technique that issues an alarm based on the predicted contact time disclosed in Patent Document 1 described above, an alarm is not performed in order to avoid frequent alarms when the inter-vehicle distance is small and the relative speed is also small. After such a setting, if the inter-vehicle distance is large and the relative speed is also large, an alarm is not issued, which may give the driver an unnatural feeling. Further, since the alarm is not issued even when the inter-vehicle distance is a normal distance and the relative speed is small, there is a problem that the device becomes inconvenient and deviates from the driver's feeling.

  The present invention has been made in view of the above circumstances, and can provide an alarm at an appropriate timing according to the relationship between the host vehicle and the preceding vehicle without giving the driver an unnatural feeling, and is a user-friendly vehicle. An object of the present invention is to provide a traveling control apparatus.

The present invention recognizes a preceding vehicle ahead of the host vehicle and acquires preceding vehicle information, and a necessary reduction necessary for following the preceding vehicle based on the traveling state of the host vehicle and the preceding vehicle information. A required deceleration calculating means for calculating a speed, a required deceleration calculating means for calculating a required deceleration generated by the deceleration means by filtering the required deceleration so as to suppress a change in behavior of the host vehicle , An alarm means for performing an alarm according to a deviation between the required deceleration and the required deceleration is provided.

  The travel control device for a vehicle according to the present invention can give an alarm at an appropriate timing according to the relationship between the host vehicle and the preceding vehicle without giving an unnatural feeling to the driver, and has the effect of being easy to use. .

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 5 show an embodiment of the present invention, FIG. 1 is a schematic configuration diagram of a travel control device mounted on a vehicle, FIG. 2 is a flowchart of an automatic tracking control program, and FIG. 3 calculates a required deceleration. FIG. 4 is an explanatory diagram showing an example of a map of basic determination threshold values set in accordance with the predicted contact time, and FIG. 5 is an inter-vehicle distance from the preceding vehicle (hereinafter simply referred to as “inter-vehicle distance”). FIG. 6 is an explanatory diagram showing an example of a map of the first threshold gain set in response to the second speed set in accordance with the relative speed with the preceding vehicle (hereinafter simply referred to as “relative speed”). FIG. 7 is an explanatory diagram showing an example of a third threshold gain map set according to the road gradient, and FIG. 8 is set according to the deceleration control start time. It is explanatory drawing which shows an example of the map of a 4th threshold gain. .

  In FIG. 1, reference numeral 1 denotes a vehicle (host vehicle) such as an automobile, and the host vehicle 1 is equipped with a cruise control system (ACC (Adaptive Cruise Control) system) 2 as an example of a travel control device.

  The ACC system 2 includes a stereo camera 3, a stereo image recognition device 4, a travel control unit 5, and the like as main parts. The ACC system 2 is basically in a constant speed travel control state in which no preceding vehicle exists. When the vehicle travels while maintaining the vehicle speed set by the driver and there is a preceding vehicle, the vehicle is controlled by an automatic follow-up control program shown in FIG.

  The stereo camera 3 is composed of a pair of (left and right) CCD cameras using a solid-state image sensor such as a charge coupled device (CCD) as a stereo optical system. Are attached at regular intervals, and an object outside the vehicle is imaged in stereo from different viewpoints and output to the stereo image recognition device 4.

  Further, the host vehicle 1 is provided with a vehicle speed sensor 6 that detects the host vehicle speed V0, and the detected host vehicle speed V0 is output to the stereo image recognition device 4 and the travel control unit 5.

  The stereo image recognition device 4 receives the image from the stereo camera 3 and the vehicle speed V0 from the vehicle speed sensor 6 and detects the front information of the three-dimensional object data and the white line data ahead of the vehicle 1 based on the image from the stereo camera 3. Then, the traveling path of the host vehicle 1 (the host vehicle traveling path) is estimated. Then, the preceding vehicle ahead of the host vehicle 1 is extracted and the inter-vehicle distance L, the preceding vehicle speed ((ratio of change in the inter-vehicle distance L) + (own vehicle speed V0)) Vf, the preceding vehicle deceleration (the differential value of the preceding vehicle speed Vf). ) Output data to the travel control unit 5 such as af, stationary object position other than the preceding vehicle, white line coordinates, white line recognition distance, own vehicle travel path coordinates, and the like.

  Here, the processing of the image from the stereo camera 3 in the stereo image recognition device 4 is performed as follows, for example. First, distance information is generated based on the principle of triangulation from a corresponding positional shift amount for a pair of stereo images in the traveling direction of the host vehicle 1 captured by the stereo camera 3. And based on this distance information, compared with well-known grouping processing and pre-stored three-dimensional road shape data, solid object data, etc., white line data, guardrails, curbs, etc. existing along the road Side wall data and three-dimensional object data such as vehicles are extracted. In the three-dimensional object data, a distance to the three-dimensional object and a temporal change (relative speed with respect to the own vehicle 1) of this distance are obtained. In particular, in the closest vehicle on the own vehicle traveling path, in the substantially same direction as the own vehicle 1. A vehicle traveling at a predetermined speed (for example, 0 km / h or more) is extracted as a preceding vehicle. Of the preceding vehicles, in particular, a vehicle having a speed Vf of about 4 km / h or less and not accelerating is recognized as a preceding vehicle in a substantially stopped state. Moreover, the obstacle which exists ahead of the own vehicle is also handled like the above-mentioned preceding vehicle. Thus, the stereo camera 3 and the stereo image recognition device 4 are provided as preceding vehicle recognition means.

  The traveling control unit 5 realizes a constant speed traveling control function for performing constant speed traveling control so as to maintain a traveling speed set by a driver's operation input, and an automatic tracking control function shown in FIG. Are connected to a constant speed travel switch 7, a stereo image recognition device 4, a vehicle speed sensor 6, and the like that are configured by a plurality of switches coupled to a constant speed travel operation lever provided on a side portion of the steering column. .

  The constant speed travel switch 7 is a vehicle speed set switch for setting a target vehicle speed during constant speed travel, a coast switch for mainly changing the target vehicle speed to the lower side, a resume switch for mainly changing the target vehicle speed to the upper side, etc. It is configured. Further, a main switch (not shown) for turning ON / OFF constant speed traveling control and automatic tracking control is disposed in the vicinity of the constant speed traveling operation lever.

  When the driver turns on a main switch (not shown) and sets a desired vehicle speed by means of a constant speed traveling operation lever, a signal from the constant speed traveling switch 7 is input to the traveling control unit 5. Then, the vehicle speed detected by the vehicle speed sensor 6 is output as a signal to the throttle valve control device 8 so as to converge to the set vehicle speed set by the driver, and the opening degree of the throttle valve 9 is feedback-controlled so that the vehicle 1 is kept at a constant speed. The vehicle is automatically driven in the state, or the automatic brake is operated by outputting a deceleration signal to the automatic brake control device 10 as a deceleration means.

  Further, when the traveling control unit 5 performs constant speed traveling control and recognizes a preceding vehicle by the stereo image recognition device 4, the traveling control unit 5 is automatically switched to automatic tracking control described later under a predetermined condition. . The constant speed traveling control function and the automatic follow-up control function are canceled when the vehicle speed V0 exceeds a preset upper limit value or when the main switch is turned off.

  In the automatic follow-up control in the travel control unit 5, the necessary deceleration Ga1 necessary for following the preceding vehicle is calculated based on the traveling state of the host vehicle 1 and the preceding vehicle information, and automatic braking is performed based on the necessary deceleration Ga1. The requested deceleration Ga2 generated by the control device 10 is calculated. Then, a deviation (deceleration deviation) ΔG between the required deceleration Ga1 and the required deceleration Ga2 is calculated, and this deceleration deviation ΔG is calculated in advance as a predicted contact time with the preceding vehicle (hereinafter simply referred to as “contact predicted time”). The determination threshold value CG set according to the TTC, the inter-vehicle distance L, the relative speed (V0−Vf), the road gradient SL, and the time after starting the control of the automatic brake control device 10 (deceleration control start time) Tbr is set. When it exceeds, a warning alarm is displayed on the liquid crystal monitor 11 as a warning means, and a driver's brake operation is urged. That is, the traveling control unit 5 is configured to have functions as necessary deceleration calculation means, required deceleration calculation means, and alarm means.

  As shown in FIG. 2, the automatic follow-up control program in the travel control unit 5 first includes necessary parameters at step (hereinafter abbreviated as “S”) 101, specifically, the preceding vehicle speed Vf, the preceding vehicle deceleration af, The preceding vehicle information such as the inter-vehicle distance L and the vehicle speed V0 are read, and the process proceeds to S102.

In S102, the necessary deceleration Ga1 necessary for following the preceding vehicle is calculated by the following equation (1), for example. The relationship between the host vehicle 1 and the preceding vehicle as shown in FIG. 3, that is, the current vehicle speed V0, the host vehicle deceleration a0, the preceding vehicle speed Vf, the preceding vehicle deceleration af, and the inter-vehicle distance L is t After a second, the host vehicle 1 moves forward by a distance Ls, the preceding vehicle moves forward by a distance Lf to the predicted preceding vehicle position, and the inter-vehicle distance from the host vehicle 1 becomes a target inter-vehicle distance Dtgt (a distance set by a map or calculation). ,
Ga1 = (V0−Vf) ² / (2 · (L−Dtgt)) + af · α1 · α2 · α3
... (1)
Here, α1, α2, and α3 are constants set in advance from a relative speed table, an inter-vehicle distance table, and a preceding vehicle speed table, respectively.

Next, in S103, the required deceleration Ga2 generated by the automatic brake control device 10 is calculated. This required deceleration Ga2 is set based on the required deceleration Ga1, and for example, is calculated by filtering the value of the required deceleration Ga1 (processing so as to suppress a sudden change in behavior in the host vehicle). To do. Then, restricted with fixed upper limit value ^{(e.g., 0.25G 1G = 9.8m / s 2} ), is adapted to set.

Next, in S104, the deceleration deviation ΔG is calculated by the following equation (2).
ΔG = | Ga1−Ga2 | (2)
Next, the process proceeds to S105, and the determination threshold value CG is calculated by, for example, the following expression (3).
CG = K1, K2, K3, K4, K0 (3)
Here, K0 is a basic determination threshold value set according to the predicted contact time TTC (= L / (V0−Vf)). For example, in the map as shown in FIG. The value is preset. K1 is a first threshold gain set according to the inter-vehicle distance L. For example, in a map as shown in FIG. 5, the value is set in advance as the inter-vehicle distance L increases. K2 is a second threshold gain set in accordance with the relative speed (V0-Vf). For example, in the map as shown in FIG. 6, the value increases in advance as the relative speed (V0-Vf) increases. Is set. K3 is a third threshold gain set according to the road surface gradient SL. For example, in the map as shown in FIG. 7, the value is set in advance as the road surface gradient SL increases. The road surface gradient SL is obtained from a known technique such as calculation from the own vehicle speed V0 and acceleration a0 or data from a navigation device. K4 is a fourth threshold gain set according to the deceleration control start time Tbr. For example, in the map as shown in FIG. 8, the value is preset in advance as the deceleration control start time Tbr increases. .

  Then, the process proceeds to S106, where the deceleration deviation ΔG is compared with the determination threshold value CG. When the deceleration deviation ΔG exceeds the determination threshold value CG (when ΔG> CG), the process proceeds to S107, and an alarm is given to the liquid crystal monitor 11. While displaying an alarm and prompting the driver to operate the brake, if the deceleration deviation ΔG is equal to or less than the determination threshold value CG (when ΔG ≦ CG), the program exits without performing an alarm.

  As described above, according to the embodiment of the present invention, the deceleration deviation ΔG between the required deceleration Ga1 and the required deceleration Ga2 is calculated in advance from the predicted contact time TTC, the inter-vehicle distance L, the relative speed (V0−Vf), When the judgment threshold value CG set according to the road surface gradient SL and the deceleration control start time Tbr is exceeded, an alarm alarm is displayed on the liquid crystal monitor 11 to control the driver's brake operation. For this reason, it is not merely an alarm according to the inter-vehicle distance L and the relative speed (V0-Vf), but the control becomes closer to the driver's sense, and without giving the driver an unnatural feeling, An alarm can be given at an appropriate timing in the relationship, and there is an effect that it is easy to use. For example, when the preceding vehicle suddenly decelerates, or when the required deceleration Ga2 is insufficient with respect to the required deceleration Ga1 in the system, the driver can be urged to perform the brake operation accurately.

  In the present embodiment, the determination threshold CG is set according to the predicted contact time TTC, the inter-vehicle distance L, the relative speed (V0−Vf), the road surface gradient SL, and the deceleration control start time Tbr. , Any one or any combination may be set.

  In the present embodiment, the preceding vehicle is recognized based on the image from the stereo camera. However, other technologies, for example, those that recognize based on information from the millimeter wave radar and the monocular camera are used. Alternatively, it may be recognized by information from a laser radar.

  Furthermore, in the present embodiment, warning is performed using a warning alarm, but the same effect as in the present invention can be obtained even if this is replaced with various means for prompting an operation by a driver.

Schematic configuration diagram of a travel control device mounted on a vehicle Flow chart of automatic tracking control program Explanatory diagram of parameters used in mathematical formula to calculate necessary deceleration Explanatory drawing which shows an example of the map of the basic determination threshold value set according to contact estimated time Explanatory drawing which shows an example of the map of the 1st threshold gain set according to the distance between vehicles Explanatory drawing which shows an example of the map of the 2nd threshold value gain set according to relative speed Explanatory drawing which shows an example of the map of the 3rd threshold value gain set according to a road surface gradient Explanatory drawing which shows an example of the map of the 4th threshold gain set according to deceleration control start time

Explanation of symbols

1 Vehicle 2 ACC system (travel control device)
3 Stereo camera (preceding vehicle recognition means)
4 Stereo image recognition device (preceding vehicle recognition means)
5 Travel control unit (necessary deceleration calculation means, required deceleration calculation means, alarm means)
8 Throttle valve control device 9 Throttle valve 10 Automatic brake control device (deceleration means)
11 LCD monitor (alarm means)

Claims (3)

A preceding vehicle recognition means for recognizing a preceding vehicle ahead of the host vehicle and acquiring preceding vehicle information;
Necessary deceleration calculating means for calculating the necessary deceleration required for following the preceding vehicle based on the traveling state of the host vehicle and the preceding vehicle information;
A required deceleration calculating means for calculating a required deceleration generated by the deceleration means by applying a filter process to the required deceleration so as to suppress a change in behavior of the host vehicle ;
Alarm means for giving an alarm according to a deviation between the required deceleration and the required deceleration;
A travel control device for a vehicle, comprising:   2. The vehicle travel control apparatus according to claim 1, wherein the warning means issues a warning when a deviation between the required deceleration and the required deceleration exceeds a preset threshold value.   The threshold values include the following distance between the preceding vehicle, the relative speed with the preceding vehicle, the predicted contact time obtained by dividing the inter-vehicle distance with the preceding vehicle by the relative speed with the preceding vehicle, the road surface gradient, 3. The vehicle travel control apparatus according to claim 2, wherein the vehicle travel control device is variably set in accordance with at least one of the time from the start of the control of the deceleration means.

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