JP2009149167A - Vehicle travel control device. - Google Patents

Abstract

A travel control device for a vehicle capable of performing deceleration control at an appropriate deceleration suitable for a driver's feeling according to a relationship with a preceding vehicle.
A travel control unit 5 includes a ratio Dr (= a ratio of an inter-vehicle distance d to a final target distance dlim, which is a target deceleration Gb for brake control when the inter-vehicle distance d is equal to or less than the final target distance dlim. (D / dlim) × 100) is variably set. As a result, deceleration due to excessive deceleration is prevented even during automatic intervention control of the brake on the premise of pre-crash control for the preceding vehicle. That is, by setting the target deceleration Gb based on the ratio Dr, even when the host vehicle 1 cuts the same distance with respect to the final target distance dlim, if the final target distance dlim is small, the deceleration is large. While ensuring accurate pre-crash control, when the final target distance dlim is large, pre-crash control is performed with a relatively small deceleration.
[Selection] Figure 1

Description

  The present invention relates to a travel control device for a vehicle that performs follow-up travel control by extending an applicable range to a low speed range.

  Conventionally, in a vehicle, a front running environment is detected by an installed camera, a laser radar device, etc., an obstacle or a preceding vehicle is recognized from the running environment data, and a target deceleration of the own vehicle is set. Many travel control devices that travel (follow-up travel control) while maintaining a constant inter-vehicle distance with respect to obstacles and preceding vehicles have been proposed. Furthermore, in recent years, a technology has been developed and put into practical use that extends the applicable range of follow-up running control to extremely low speeds and keeps the distance between vehicles constant when the preceding vehicle stops (follow-up stop control). ing.

For example, in Patent Document 1, when the host vehicle speed is higher than 20 km / h, the electronic throttle opening control and the brake actuator drive control are performed so that the inter-vehicle time with the preceding vehicle is maintained at the target time. A technique for controlling the opening of the electronic throttle and driving the brake actuator to perform acceleration / deceleration in proportion to the deviation between the inter-vehicle distance from the preceding vehicle and the minimum inter-vehicle distance (= 10 m) when the speed is 20 Km / h or less is disclosed. Yes. Further, in Patent Document 1, when the stop of the preceding vehicle is detected, the host vehicle speed is reduced to an extremely low speed (for example, 5 km / h), and when the inter-vehicle distance becomes the stop inter-vehicle distance (= 5 m). Techniques for controlling the opening of an electronically controlled throttle and driving control of a brake actuator in order to stop the vehicle are disclosed.
JP 2001-225669 A

  By the way, in this type of follow-up control, for example, when the deceleration of the preceding vehicle is large, the own vehicle may approach the preceding vehicle to an unintended distance by interrupting the minimum inter-vehicle distance or the like. In such a case, in follow-up running control, it is common to decelerate at the maximum deceleration allowed for control in order to quickly recover the inter-vehicle distance.

  However, depending on the relative relationship with the preceding vehicle or the like, there is a risk that such deceleration may be sudden deceleration that is far from the driver's feeling, and there is a need for deceleration control that better matches the driver's feeling.

  The present invention has been made in view of the above circumstances, and provides a vehicle travel control device capable of performing deceleration control at an appropriate deceleration suitable for the driver's feeling according to the relationship with the preceding vehicle. Objective.

  The present invention recognizes a preceding vehicle ahead of the host vehicle and obtains preceding vehicle information, and at least a target distance for performing the follow-up traveling with respect to the preceding vehicle between at least the host vehicle and the preceding vehicle. Target distance setting means for setting a minimum required final target distance and target deceleration setting for setting a target deceleration for brake control for maintaining the inter-vehicle distance from the preceding vehicle larger than the final target distance The target deceleration setting means can vary the target deceleration when the inter-vehicle distance is equal to or less than the final target distance in accordance with a ratio of the inter-vehicle distance to the final target distance. It is characterized by setting.

  According to the vehicle travel control device of the present invention, it is possible to perform deceleration control at an appropriate deceleration suitable for the driver's feeling according to the relationship with the preceding vehicle.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings relate to an embodiment of the present invention, FIG. 1 is a schematic configuration diagram of a driving support device mounted on a vehicle, FIG. 2 is a flowchart showing a target deceleration calculation routine for brake control, and FIG. FIG. 4 is an explanatory diagram showing the relationship between the host vehicle and each target distance, FIG. 5 is a map for setting a target deceleration when the inter-vehicle distance is larger than the final target distance, and FIG. 6 is an inter-vehicle distance map. It is a target deceleration setting map when the distance is equal to or less than the final target distance.

  In FIG. 1, reference numeral 1 denotes a vehicle (own vehicle). The vehicle 1 is mounted with a cruise control system (ACC (Adaptive Cruise Control) system) 2 with an inter-vehicle distance control function as an example of a travel control device. Yes.

  The ACC system 2 includes a stereo camera 3, a stereo image recognition device 4, a travel control unit 5, and the like. The ACC system 2 basically includes a vehicle speed set by a driver when there is no preceding vehicle. If there is a preceding vehicle, follow-up traveling control for the preceding vehicle is performed. Here, in the ACC system 2 of the present embodiment, the vehicle speed region in which the follow-up traveling control can be performed is extended not only to a predetermined high speed region but also to a very low speed region including a stop. That is, in the ACC system 2 of the present embodiment, for example, when the preceding vehicle is decelerated to an extremely low speed range equal to or lower than a predetermined vehicle speed during the following traveling control, the following traveling control is continued and the preceding vehicle is stopped due to a traffic jam or the like. Even in this case, it is possible to stop in a state where the final target distance dlim (described later) is secured as the inter-vehicle distance d.

  The stereo camera 3 is composed of a pair of left and right CCD cameras using a solid-state imaging device such as a charge coupled device (CCD) as a stereo optical system. Each of these sets of CCD cameras is mounted at a certain interval in front of the ceiling in the passenger compartment, and subjects the object outside the vehicle to stereo imaging from different viewpoints, and outputs the captured image information to the stereo image recognition device 4.

  The stereo image recognition device 4 receives image information from the stereo camera 3 and the vehicle speed V from the vehicle speed sensor 6. The stereo image recognition device 4 recognizes forward information such as three-dimensional object data and white line data ahead of the host vehicle 1 based on image information from the stereo camera 3, and estimates the host vehicle traveling path based on the recognition information and the like. To do. Furthermore, the stereo image recognition device 4 performs detection of a preceding vehicle on the own vehicle traveling path based on the recognized three-dimensional object data or the like.

  Here, the stereo image recognition device 4 performs processing of image information from the stereo camera 3 as follows, for example. First, distance information is generated on the basis of the principle of triangulation from a corresponding positional shift amount for a pair of stereo images obtained by capturing the traveling direction of the host vehicle with the stereo camera 3. Then, a well-known grouping process is performed on the distance information, and the distance information subjected to the grouping process is compared with previously stored three-dimensional road shape data, solid object data, etc. Sidewall data such as guardrails and curbs, and three-dimensional object data such as vehicles are extracted along the way. Furthermore, the stereo image recognition device 4 estimates the host vehicle travel path based on the white line data, the side wall data, and the like, and is a three-dimensional object existing on the host vehicle travel path, and has a predetermined speed in the same direction as the host vehicle 1. A vehicle moving at (for example, 0 km / h or more) is extracted (detected) as a preceding vehicle. When a preceding vehicle is detected, the preceding vehicle information includes the preceding vehicle distance d (= inter-vehicle distance), the preceding vehicle speed Vf (= (the rate of change of the inter-vehicle distance d) + (own vehicle speed V)), the preceding vehicle information. Car deceleration af (= differential value of preceding vehicle speed Vf) and the like are calculated. Of the preceding vehicles, in particular, a vehicle whose speed Vf is not more than a predetermined value (for example, 4 Km / h or less) and is not accelerated is recognized as a preceding vehicle in a substantially stopped state. Thus, in this embodiment, the stereo image recognition apparatus 4 implement | achieves the function as a preceding vehicle recognition means with the stereo camera 3. FIG.

  For example, a stereo image recognition device 4, a vehicle speed sensor 6, a constant speed travel switch 15 and the like are connected to the travel control unit 5. Here, the constant speed travel switch 15 is, for example, a vehicle speed set switch that sets the target vehicle speed Vset during constant speed travel, a coast switch that mainly changes the target vehicle speed Vset to the lowering side, A plurality of switches, such as a resume switch for changing the setting to, are connected to a constant speed traveling operation lever provided on a side portion of the steering column or the like to constitute a main part. Further, a main switch (not shown) for turning on / off ACC control (constant speed traveling control and follow-up traveling control) is disposed in the vicinity of the constant speed traveling operation lever.

  When the main switch (not shown) is turned on by the driver and the vehicle speed desired by the driver is set through the constant speed operation lever, the traveling control unit 5 causes the own vehicle speed V to converge to the target vehicle speed Vset set by the driver. The vehicle speed control is performed through the engine control unit (E / G_ECU) 7 and the brake control unit 8 (BRK_ECU). That is, the traveling control unit 5 controls the opening degree of the electronically controlled throttle valve 17 (engine output control) through the E / G_ECU 7 to converge the host vehicle speed V to the target vehicle speed Vset. Furthermore, when the traveling control unit 5 determines that sufficient deceleration cannot be obtained only by engine output control, the traveling control unit 5 performs output hydraulic pressure control (automatic brake control) from the brake booster 18 through the BRK_ECU 8. The vehicle speed V is converged to the target vehicle speed Vset.

  Further, when the preceding vehicle is recognized by the stereo image recognition device 4 during the constant speed traveling control, the traveling control unit 5 shifts from the low speed traveling control to the following traveling control. In the present embodiment, when the ACC control shifts to the follow-up travel control, the travel control unit 5 sets, for example, the follow-up target distance dtrg, the final target distance dlim, and the brake target distance dbrk as control target distances. .

  The follow target distance dtrg is the inter-vehicle distance with the target preceding vehicle in the follow traveling control, and is set as a control parameter when engine output control is performed. The final target distance dlim is set to a minimum required inter-vehicle distance between the own vehicle 1 and the preceding vehicle so as not to give the driver anxiety during the follow-up driving. Further, when the brake target distance dbrk is set to perform automatic intervention control of the brake to maintain the inter-vehicle distance d larger (longer) than the final target distance dlim when sufficient deceleration cannot be obtained only by engine output control. And is set to a distance that is not less than the final target distance dlim and shorter than the follow target distance dtrg.

  Here, in the present embodiment, for example, as shown in FIG. 3, the traveling control unit 5 shows the relationship between the follow target distance dtrg and the preceding vehicle speed Vf and the relationship between the final target distance dlim and the preceding vehicle speed Vf. A map is set and stored in advance. With reference to this map, the follow target distance dtrg and the final target distance dlim are variably set so as to increase as the preceding vehicle speed Vf increases. It should be noted that a minimum inter-vehicle distance (for example, 5 m) required when the vehicle is stopped is set as the lower limit value of the final target distance dlim set when the preceding vehicle speed Vf = 0. Also, on the map, a brake target distance reference value dbrk0 that increases as the preceding vehicle speed Vf increases is defined in an area between the follow target distance dtrg and the final target distance dlim. This brake target distance reference value dbrk0 Is basically set as the brake target distance dbrk. However, in order to realize brake control at a constant deceleration as gentle as possible until the inter-vehicle distance d reaches the final target distance dlim, in the present embodiment, the inter-vehicle distance d and the brake target distance reference value are used. When the relationship with dbrk0 satisfies a predetermined relationship set in advance, the brake target distance dbrk is a distance from the brake target distance reference value dbrk0 to the final target distance dlim, and the final target distance becomes smaller as the inter-vehicle distance d decreases. It is adjusted to gradually approach dlim.

  The following target distance dtrg, the final target distance dlim, and the brake target distance reference value dbrk0 may be obtained from other than the map, and increase as the host vehicle speed V increases instead of the preceding vehicle speed Vf. Such a variable setting may be used.

  The travel control unit 5 is for engine control based on, for example, the deviation (dtrg−d) between the follow target distance dtrg and the inter-vehicle distance d and the relative vehicle speed Vrel (= V−Vf) between the host vehicle 1 and the preceding vehicle. The target deceleration (target acceleration) Gth is set. Then, the traveling control unit 5 controls the engine output by controlling the opening / closing of the electronically controlled throttle valve 17 at an opening degree corresponding to the target deceleration Gth through the E / G_ECU 7, and the inter-vehicle distance d is set to the following target distance dtrg. To converge.

  In addition, the travel control unit 5 determines the target for brake control based on, for example, the deviation Dd (= d−dbrk) between the brake target distance dbrk and the inter-vehicle distance d and the relative vehicle speed Vrel between the host vehicle 1 and the preceding vehicle. Set the deceleration Gb. Here, for example, a map indicating the relationship between the deviation Dd, the relative vehicle speed Vrel, and the target deceleration Gb is preset and stored in the travel control unit 5 (see, for example, FIG. 5), and the target deceleration Gb is Basically, the deviation Dd is set so as to increase and as the relative vehicle speed Vrel increases, the deviation Dd increases. Then, the traveling control unit 5 performs automatic intervention control of the brake by controlling the output hydraulic pressure from the brake booster 18 with the hydraulic pressure corresponding to the target deceleration Gb through the BRK_ECU 8, and sets the inter-vehicle distance d as the final target distance. Maintain greater than dlim.

  Here, the target deceleration Gb is set, for example, such that the automatic intervention control of the brake is terminated when the own vehicle 1 reaches the brake target distance dbrk (the relative vehicle speed Vrel becomes substantially “0”). . Further, when the deviation Dd is large by a predetermined value or when the relative vehicle speed Vrel is small by a predetermined value, the target deceleration Gb is set to “0”, thereby substantially prohibiting automatic braking intervention.

  By the way, the above-mentioned target deceleration Gb is set with the maximum deceleration (for example, 0.25 G) permitted by law for ACC control as an upper limit. Therefore, for example, when the preceding vehicle suddenly decelerates, the deceleration of the own vehicle 1 with respect to the preceding vehicle becomes insufficient, and the inter-vehicle distance d may be less than the final target distance dlim. In such a case, in order to quickly recover the inter-vehicle distance d to a state larger than the final target distance dlim, the traveling control unit 5 determines, for example, the inter-vehicle distance d> based on the inter-vehicle distance d and the final target distance dlim. A target deceleration Gb having a characteristic different from that of the final target distance dlim is set.

Specifically, when the inter-vehicle distance d ≦ the final target distance dlim, the traveling control unit 5 determines the ratio Dr (= d / dlim) × 100) that the inter-vehicle distance d occupies with respect to the final target distance dlim. The target deceleration Gb is set based on the relative vehicle speed Vrel between the host vehicle 1 and the preceding vehicle. Here, for example, a map indicating the relationship between the ratio Dr, the relative vehicle speed Vrel, and the target deceleration Gb is preset and stored in the travel control unit 5 (see, for example, FIG. 6). In this map, each value G1,1, G1,2, G1,3,..., G1, n-2, G1, n-1, G1, set as the target deceleration Gb when the ratio Dr = 100%. n is set to be equal to the values Gk, 1, Gk, 2, Gk, 3,..., Gk, l-2, Gk, l-1, Gk, l on the map shown in FIG. Furthermore, each value on the map is set so as to increase as the ratio Dr decreases and increase as the relative vehicle speed Vrel increases. Thus, for example, the target deceleration Gb when the relative vehicle speeds Vrel are equal is a value that is substantially higher than the value set when the inter-vehicle distance d> the final target distance dlim. Also, the value of the target deceleration Gb does not change suddenly when the vehicle distance d> the final target distance dlim is changed to the vehicle distance d ≦ the final target distance dlim.

  Then, the travel control unit 5 controls the output of hydraulic pressure from the brake booster 18 with the hydraulic pressure corresponding to the target deceleration Gb through the BRK_ECU 8, thereby automatically intervening control of the brake on the premise of pre-crash control for the preceding vehicle. (Strong brake control) is performed, and the inter-vehicle distance d is quickly recovered to a distance larger than the final target distance dlim.

  Thus, in this embodiment, the traveling control unit 5 has functions as target distance setting means and target deceleration setting means.

Next, a brake control target deceleration Gb setting routine executed by the travel control unit 5 will be described with reference to the flowchart shown in FIG.
This routine is repeatedly executed every set time. When the routine is started, the travel control unit 5 firstly, in step S101, the brake target distance reference value dbrk0 and the final target distance dlim according to the current preceding vehicle speed Vf. Is calculated with reference to a preset map (see FIG. 3), and these deviations (target distance deviation) d1 are further calculated.

  In subsequent step S102, the traveling control unit 5 checks whether or not the current inter-vehicle distance d is larger than the sum (dbrk0 + d1) with the brake target distance reference value dbrk0 target distance deviation d1.

  If it is determined in step S102 that d> dbrk0 + d1 (see FIG. 4A), the traveling control unit 5 proceeds to step S104, and uses the brake target distance reference value dbrk0 calculated in step S101 as the brake target distance. After setting as dbrk, the process proceeds to step S106.

  On the other hand, when it is determined in step S102 that d ≦ dbrk0 + d1, the traveling control unit 5 proceeds to step S103 and checks whether the inter-vehicle distance d is greater than the final target distance dlim.

  When it is determined in step S103 that d> dlim (see FIG. 4B), the traveling control unit 5 has a half value of the sum of the final target distance dlim and the inter-vehicle distance d ((dlim + d) / 2). Is set as the brake target distance dbrk, and then the process proceeds to step S106. As a result, the brake target distance dbrk in the case of dbrk0 + d1 ≧ d> dlim is gradually brought closer to the final target distance dlim as the inter-vehicle distance d decreases.

  When the process proceeds from step S104 or step S105 to step S106, the traveling control unit 5 calculates a deviation Dd (= d−dbrk) between the inter-vehicle distance d and the brake target distance dbrk, and in the subsequent step S107, the relative vehicle speed Vrel and the deviation are calculated. After calculating the target deceleration Gb corresponding to Dd with reference to a preset map (see FIG. 5), the routine is exited.

  On the other hand, when it is determined in step S103 that the inter-vehicle distance d ≦ dlim (see FIG. 4C), the traveling control unit 5 proceeds to step S108, and the ratio of the inter-vehicle distance d to the final target distance dlim. Dr (= (d / dlim) × 100) is calculated, and in the subsequent step S109, the target deceleration Gb corresponding to the relative vehicle speed Vrel and the ratio Dr is referred to a preset map (see FIG. 6). After the calculation, exit the routine.

  According to such an embodiment, the ratio Dr (= () of the inter-vehicle distance d occupying the target deceleration Gb for brake control when the inter-vehicle distance d becomes equal to or less than the final target distance dlim. d / dlim) × 100) to prevent deceleration due to excessive deceleration even during automatic intervention control of the brake (strong brake control) based on pre-crash control for the preceding vehicle. Therefore, deceleration control can be performed at an appropriate deceleration suitable for the driver's feeling. That is, by setting the target deceleration Gb on the basis of the ratio Dr, even if the host vehicle 1 cuts the same distance with respect to the final target distance dlim, a large decrease is achieved when the final target distance dlim is small. While achieving accurate pre-crash control at speed, pre-crash control can be performed with relatively small deceleration when the final target distance dlim is large, with appropriate deceleration suitable for the driver's feeling. Deceleration control can be performed.

  In the above-described embodiment, an example in which the following traveling control is performed using the following target distance dtrg and the brake target distance dbrk when the inter-vehicle distance d is larger than the final target distance dlim has been described. The following traveling control when the inter-vehicle distance d is larger than the final target distance dlim may be performed based on a known inter-vehicle time or the like instead of the following target distance dtrg and the brake target distance dbrk. Of course.

Schematic configuration diagram of a driving support device mounted on a vehicle Flow chart showing a target deceleration calculation routine for brake control Map showing the relationship between the preceding vehicle speed and each target distance Explanatory diagram showing the relationship between the vehicle and each target distance Target deceleration setting map when the inter-vehicle distance is greater than the final target distance Target deceleration setting map when the inter-vehicle distance is less than or equal to the final target distance

Explanation of symbols

1 ... Vehicle (own vehicle)
2 ... ACC system 3 ... Stereo camera (preceding vehicle recognition means)
4 ... Stereo image recognition device (preceding vehicle recognition means)
5 ... Travel control unit (target distance setting means, target deceleration setting means)
6 ... Vehicle speed sensor 7 ... Engine control unit 8 ... Brake control unit 15 ... Constant speed travel switch 17 ... Electronically controlled throttle valve 18 ... Brake booster d ... Inter-vehicle distance dtrg ... Tracking target distance dbrk0 ... Brake target distance reference value dbrk ... Brake target Distance dlim ... Final target distance d1 ... Target distance deviation Dd ... Deviation Dr ... Ratio Gth ... Target deceleration Gb ... Target deceleration V ... Own vehicle speed Vf ... Preceding vehicle speed Vrel ... Relative vehicle speed Vset ... Target vehicle speed

Claims (1)

A preceding vehicle recognition means for recognizing a preceding vehicle ahead of the host vehicle and acquiring preceding vehicle information;
Target distance setting means for setting at least a final target distance necessary between the own vehicle and the preceding vehicle as a target distance for performing the follow-up traveling with respect to the preceding vehicle,
A target deceleration setting means for setting a target deceleration for brake control for maintaining the inter-vehicle distance with the preceding vehicle larger than the final target distance;
The target deceleration setting means variably sets the target deceleration when the inter-vehicle distance is equal to or less than the final target distance according to a ratio of the inter-vehicle distance to the final target distance. A vehicle travel control device.

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