JP3747989B2 - Vehicle travel control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle travel control device, and more particularly to a deceleration control technique in travel control.
[0002]
[Related background]
In recent years, in order to reduce the driving operation of an automobile, a travel control device including an inter-vehicle distance control device has been developed and put into practical use for tracking the preceding vehicle.
[0003]
The travel control device including the inter-vehicle distance control device detects the inter-vehicle distance between the host vehicle and the preceding vehicle based on information from a front recognition device such as a camera or a laser radar. The engine output and the braking force are adjusted so that the set target inter-vehicle distance is obtained, whereby the vehicle is accelerated and decelerated to track the preceding vehicle.
[0004]
Usually, in such a travel control device, the target deceleration is calculated based on the relative speed between the host vehicle speed and the preceding vehicle speed, and when the vehicle is decelerated, the braking force is applied based on the target deceleration. The vehicle is decelerated and controlled.
[0005]
By the way, when the tracking traveling control is being performed, it is only necessary that the preceding vehicle is always the same vehicle, but the preceding vehicle is often replaced by interruption of another vehicle.
[0006]
Thus, when the other vehicle enters the range of the original target inter-vehicle distance, the inter-vehicle distance decreases discontinuously and rapidly, and the own vehicle suddenly brakes accordingly, and the vehicle occupant decelerates. There is a possibility of feeling uncomfortable, such as a shock.
[0007]
Therefore, when another vehicle is interrupted in this way, a pseudo inter-vehicle distance is assumed that the inter-vehicle distance does not become discontinuous and is gradually displaced, and the vehicle speed is controlled based on the pseudo inter-vehicle distance. An apparatus configured to avoid sudden deceleration of a vehicle is disclosed in Japanese Patent Application Laid-Open No. 8-127268.
[0008]
[Problems to be solved by the invention]
However, the device disclosed in the above publication performs control using the concept of pseudo inter-vehicle distance that does not actually exist, and there is a problem in the traveling safety of the vehicle.
[0009]
In other words, in the control of the device, the own vehicle is far longer than the shortened inter-vehicle distance for a while, even though the inter-vehicle distance is actually shortened rapidly due to interruption of another vehicle. Tracking is controlled with the aim of a pseudo inter-vehicle distance, that is, a position considerably ahead of other vehicles, and it is actually not preferable for safety because it is traveling without looking at the other vehicles that have interrupted. is there.
[0010]
According to the apparatus, for example, when another vehicle decelerates after interruption, there is a possibility that the own vehicle may inadvertently approach the other vehicle without following the deceleration of the other vehicle. .
[0011]
The present invention has been made on the basis of the above-described circumstances, and the object of the present invention is to prevent the vehicle from decelerating suddenly and to ensure safety when another vehicle interrupts between the vehicle and the preceding vehicle. Is to provide a travel control device for a vehicle that can maintain a high value.
[0012]
[Means for Solving the Problems]
In order to achieve the above-described object, according to the first aspect of the present invention, a travel control device for a vehicle that performs travel control by controlling the vehicle speed of the host vehicle so that the inter-vehicle distance between the host vehicle and the preceding vehicle becomes the target inter-vehicle distance. The target deceleration calculation means calculates the target deceleration of the host vehicle based on the relative speed between the host vehicle speed and the preceding vehicle speed, the inter-vehicle distance, and the target inter-vehicle distance, and the braking control unit calculates the above-described braking device. The operation is controlled based on the target deceleration. It is set based on either the host vehicle speed or the preceding vehicle speed. When it becomes shorter and shorter than the target inter-vehicle distance, The braking start distance setting means sets the braking start distance of the host vehicle based on the host vehicle speed and the relative speed, By means of target vehicle distance reduction means The target inter-vehicle distance depends on the ratio of the suddenly decreased inter-vehicle distance to the braking start distance. Reduced.
[0013]
In other words, when another vehicle has interrupted between the host vehicle and the preceding vehicle during tracking control, the inter-vehicle distance between the host vehicle and the other vehicle that has interrupted suddenly decreases. However, in such a case, the target inter-vehicle distance is reduced according to the shortened inter-vehicle distance, and the target deceleration is reduced.
[0014]
Therefore, even if another vehicle is interrupted between the host vehicle and the preceding vehicle, the host vehicle will be slowly decelerated without sudden braking, and the passenger will not feel a deceleration shock. Smooth tracking control is realized.
[0015]
In addition, although the target vehicle distance always exists in spite of such reduction, it is possible to suitably prevent the vehicle from inadvertently approaching another vehicle that has been interrupted, and driving safety is improved. Secured well.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, there is shown a schematic configuration diagram of a travel control device according to the present invention mounted on a vehicle 1, and the configuration of the travel control device according to the present invention will be described below based on the same diagram.
[0017]
A scanning system that emits a laser beam toward the front of the vehicle 1, recognizes an object positioned in front of the vehicle 1 by scanning the laser beam, and further measures a distance to the object. A laser radar 2 is provided. A CCD camera 4 that captures the front of the vehicle 1 is attached to the roof of the vehicle interior. The CCD camera 4 can also recognize an object, a lane (white line), and the like located in front.
[0018]
The engine 6 is connected to a throttle valve 8 that controls the amount of intake air to the engine 6 and adjusts the engine output. Specifically, the throttle valve 8 can automatically adjust the valve opening based on an operation signal output from an electronic control unit (ECU) 50 described later according to the opening of an accelerator pedal (not shown). A throttle actuator 12 is provided.
[0019]
A pair of left and right front wheels (drive wheels) 20 and 20 and a pair of left and right rear wheels (sub wheels) 22 and 22 are provided with service brakes (braking devices) 24 such as hydraulic disc brakes, respectively. It is connected to a brake pedal 28 via a brake master cylinder 26 having a negative pressure booster. Further, the brake master cylinder 26 is provided with a negative pressure type brake actuator 30 that can automatically operate the service brake 24 in accordance with an operation signal from the ECU 50 regardless of an input from the brake pedal 28.
[0020]
Further, wheel speed sensors 32 for detecting the right wheel speed VSR and the left wheel speed VSL are provided in the vicinity of the rear wheels 22 and 22 which are the sub wheels corresponding to the respective wheels. These wheel speed sensors 32 and 32 function as own vehicle speed detecting means for detecting the own vehicle speed Ve.
[0021]
The steering column 36 of the steering wheel 34 provided in the vehicle interior of the vehicle 1 is provided with a tracking travel switching operation switch 38 that switches the traveling control device of the vehicle 1 between a normal traveling state and a traveling state by tracking traveling control. Yes. When the tracking travel switching operation switch 38 is operated to the set side, inter-vehicle distance control, that is, tracking travel control, is started, and when operated to the reset side, the inter-vehicle distance control is canceled.
[0022]
The ECU 50 is a main control device that controls various controls of the vehicle 1. As shown in the figure, various sensors and switches such as the scanning laser radar 2, the CCD camera 4, the wheel speed sensors 32 and 32, and the tracking travel switching operation switch 38 are connected to the input side of the ECU 50. On the output side, various drive devices such as the throttle actuator 12 and the brake actuator 30 are connected.
[0023]
Hereinafter, the control content of the traveling control device configured as described above, that is, the operation and effect according to the present invention will be described.
[0024]
Referring to FIG. 2, there is shown a flowchart of a tracking travel control routine. Hereinafter, the control procedure of the tracking travel control according to the present invention will be described with reference to FIG.
[0025]
When the tracking travel switching operation switch 38 is operated to the set side and the tracking travel control is started, first, in step S10, a preceding vehicle determination process is performed. Specifically, in step S10, when an object is recognized in front of the vehicle 1 based on information from the scanning laser radar 2 or the CCD camera 4, it is determined whether or not the object is a vehicle. If it is determined that the vehicle is a vehicle, the vehicle is determined to be a preceding vehicle. When there are a plurality of preceding vehicles, for example, a vehicle located on the own vehicle lane recognized by the CCD camera 4 or on the own vehicle lane estimated by the own vehicle steering angle is determined as the preceding vehicle. Thereby, a preceding vehicle is decided. Since the method for determining the preceding vehicle is not directly related to the present invention, a detailed description thereof is omitted.
[0026]
In step S12, the vehicle speed of the vehicle 1, that is, the own vehicle speed Ve is calculated based on the information from the wheel speed sensors 32, 32 (own vehicle speed detecting means). Here, the host vehicle speed Ve is calculated by the following equation (1), for example.
[0027]
Ve = (VSR + VSL) / 2 (1)
That is, the host vehicle speed Ve is an average value of the right wheel speed VSR and the left wheel speed VSL.
[0028]
In step S14, the distance from the own vehicle to the preceding vehicle, that is, the inter-vehicle distance L is accurately measured based on the information from the scanning laser radar 2 (inter-vehicle distance detecting means).
[0029]
In the next step S16, the relative speed Vr between the host vehicle and the preceding vehicle is calculated based on the inter-vehicle distance information L. Specifically, the relative speed Vr is calculated based on the value of the inter-vehicle distance information L when the routine is executed last time, that is, the amount of change ΔL between the previous value and the current value. At this time, if the amount of change ΔL is positive and the relative speed Vr is positive, it can be considered that the vehicle is moving away from the preceding vehicle, and if the amount of change ΔL is negative and the relative speed Vr is negative, the vehicle approaches the preceding vehicle. Can be regarded as doing.
[0030]
In step S18, the preceding vehicle speed Vf is calculated from the following equation (2) based on the host vehicle speed Ve and the relative speed Vr (preceding vehicle speed detecting means).
[0031]
Vf = Ve + Vr (2)
Here, the preceding vehicle acceleration αf is also calculated by differentiating the preceding vehicle speed Vf. Specifically, the preceding vehicle acceleration αf is calculated from the amount of change ΔVf between the previous value and the current value of the preceding vehicle speed information Vf when the routine was executed last time.
[0032]
In the next step S20, a target deceleration rate αe of the own vehicle is calculated.
[0033]
Referring to FIG. 3, a calculation processing routine for the target deceleration rate αe is shown. The calculation procedure for the target deceleration rate αe will be described below based on the flowchart.
[0034]
In step S40, first, a target deceleration rate αer of the host vehicle during deceleration traveling of the preceding vehicle is calculated from the following equation (3).
[0035]
αer = −Vr · Ve / (L−Lo) (3)
Here, Lo indicates the minimum inter-vehicle distance that should be secured between the host vehicle and the preceding vehicle when it is assumed that the preceding vehicle has decelerated and stopped.
[0036]
The minimum inter-vehicle distance Lo is made variable according to the inter-vehicle distance L. When the inter-vehicle distance L is separated by a value L1 (for example, 25 m) or more, the minimum inter-vehicle distance Lo is 0. When the inter-vehicle distance L becomes less than the value L1, the minimum inter-vehicle distance Lo is set to a value Lo1 (for example, 10 m).
[0037]
That is, when the inter-vehicle distance L decreases and the host vehicle approaches the preceding vehicle, the target deceleration rate αer is increased so as to secure at least the minimum inter-vehicle distance Lo, and thereby the host vehicle contacts the preceding vehicle. I am trying not to have it.
[0038]
Subsequently, in step S42, the target deceleration rate αec of the host vehicle traveling at a constant speed of the preceding vehicle is calculated from the following equation (4) (target deceleration calculation means).
[0039]
αec = Vr ² / 2 ・ (L−Lf ・ L / La) + αa (4)
Here, Lf is a target inter-vehicle distance based on the preceding vehicle speed calculated according to the preceding vehicle speed Vf. Specifically, the ECU 50 stores in advance a map indicating the relationship between Vf and Lf as shown in FIG. 4, and the target inter-vehicle distance Lf is obtained from the map (target inter-vehicle distance calculation means).
[0040]
That is, the larger one of the target inter-vehicle distance Lf1 when the minimum inter-vehicle distance Lo is 0 and the target inter-vehicle distance Lf2 when the minimum inter-vehicle distance Lo is a value Lo1 (for example, 10 m) (solid line). Value) is selected as the target inter-vehicle distance Lf, and when the preceding vehicle speed Vf is large, the target inter-vehicle distance Lf is set based on the target inter-vehicle distance Lf1, and when the preceding vehicle speed Vf decreases, at least the minimum inter-vehicle distance It is set based on the target inter-vehicle distance Lf2 so as to ensure the distance Lo or more.
[0041]
By the way, in the same equation, the target inter-vehicle distance Lf is multiplied by L / La. As shown in FIG. 10, this L / La is another vehicle (interrupt vehicle) between the own vehicle and the preceding vehicle. Is a correction coefficient provided in consideration of a case where the engine suddenly interrupts (target inter-vehicle distance reduction means).
[0042]
Here, La is preset based on the vehicle speed Ve and the relative speed Vr, and is a braking start distance when the vehicle approaches the preceding vehicle. The relationship between Ve, Vr and La as shown in FIG. It is set based on a map showing (Brake start distance setting means) .
[0043]
That is, when another vehicle suddenly cuts in, the inter-vehicle distance L newly indicates the inter-vehicle distance between the other vehicle and the host vehicle, and the new inter-vehicle distance L is instantly determined as the braking start distance La. However, in such a case, the target inter-vehicle distance Lf is corrected (reduced) according to the degree of interruption of the inter-vehicle distance L with respect to the braking start distance La, that is, L / La. Yes (see FIG. 10).
[0044]
As a result, when another vehicle suddenly cuts in, the target inter-vehicle distance is reduced, so that the target deceleration rate αer is changed to be small, and the host vehicle slowly decelerates without sudden braking.
[0045]
That is, referring to FIG. 11, the time change of the own vehicle speed Ve and the inter-vehicle distance L when another vehicle suddenly interrupts is shown. In FIG. 11, the solid line indicates the target inter-vehicle distance Lf according to L / La. Although the case where it corrects is shown and the broken line has shown the case where the said correction is not performed, when L / La is considered, the own vehicle speed Ve decelerates slowly, and although the inter-vehicle distance L becomes temporarily small, the whole Will gradually increase. Therefore, even when there is an interruption, the passenger of the vehicle 1 is preferably prevented from feeling a deceleration shock.
[0046]
When the original preceding vehicle is well tracked without interruption by another vehicle, or after the interruption, the inter-vehicle distance L gradually increases and becomes greater than the braking start distance La. When the correction coefficient L / La exceeds the value 1, the correction coefficient L / La is clipped to the value 1, and the target inter-vehicle distance is set to the normal target inter-vehicle distance Lf based on the map of FIG.
[0047]
In addition, αa in the equation is a correction value based on fluctuations in the preceding vehicle acceleration αf, and is calculated from the following equation (5).
[0048]
αa = αf · (L−Le · L / La) / (L−Lf · L / La) (5)
Here, Le is a target inter-vehicle distance at the time of follow-up control set based on the own vehicle speed Ve. Specifically, as shown in FIG. 6, the ECU 50 stores in advance a map indicating the relationship between Ve and Le as in FIG. 4, and the target inter-vehicle distance Le is obtained from the map.
[0049]
Also in the calculation formula of the correction value αa, the target inter-vehicle distance Le and the target inter-vehicle distance Lf are corrected by the correction coefficient L / La. Therefore, the correction value αa is an appropriate value considering interruptions of other vehicles. It is a correction value.
[0050]
When the target deceleration rate αer of the subject vehicle that is decelerating the preceding vehicle and the target deceleration rate αec of the subject vehicle that is traveling at the constant speed of the preceding vehicle are determined as described above, the target deceleration rate is obtained in the next step S44 and step S46. Find weights for αer and target deceleration rate αec.
[0051]
In step S44, first, a weight W1 based on the preceding vehicle acceleration αf is calculated.
[0052]
Specifically, the ECU 50 stores in advance a map indicating the relationship between the preceding vehicle acceleration αf and the weight W1 as shown in FIG. 7, and the weight W1 is obtained from the map.
[0053]
That is, the weight W1 gradually increases from the value 0 when the preceding vehicle acceleration αf decreases to the negative side, that is, when the preceding vehicle deceleration increases and becomes a predetermined value αf1 (for example, −0.05 G) or less. The value is set to 1 when αf2 (for example, −0.2 G) is reached.
[0054]
In step S46, a weight W2 based on the tracking state counter CNT is calculated.
[0055]
Specifically, the ECU 50 previously stores a map showing the relationship between the tracking state counter CNT and the weight W2 as shown in FIG. 8 in the same manner as described above, and the weight W2 is obtained from the map.
[0056]
Here, the tracking state counter CNT is a counter that is added every execution period of the routine when the vehicle 1 is in the tracking state with respect to the preceding vehicle, and is tracked when at least the following conditions 1) to 3) are satisfied. The state is determined and added.
[0057]
1) (Control state) ≠ (Brake control)
2) L <Le · 3/2
3) | Vr | <Vr1 (for example, 5 km / h)
That is, when the vehicle 1 enters the tracking state, the tracking state counter CNT starts to be added, but the weight W2 exceeds the predetermined value CNT1 (for example, a value corresponding to 0.5 sec). The value is set so as to gradually increase from 0 and reach 1 when a predetermined value CNT2 (for example, a value corresponding to 2.0 sec) is reached. That is, the weight W2 is made to approach the value 1 as the duration of the tracking state becomes longer.
[0058]
As described above, when the weight W1 based on the preceding vehicle acceleration αf and the weight W2 based on the tracking state counter CNT are respectively obtained from each map, in the next step S48, the weight W1, the weight W2, and the previous value Wn−1 The largest one is selected and this value is set as the weight W.
[0059]
In step S50, the weighted average of the target deceleration αer during the preceding vehicle decelerating traveling and the target deceleration αec during the preceding vehicle constant speed traveling is calculated from the following equation (6) in consideration of the weight W. The weighted average value is finally set as the target deceleration rate αe.
[0060]
αe = αec · (1−W) + αer · W (6)
In this way, by calculating the target deceleration rate αe in consideration of the weight W, for example, after the vehicle catches up to the preceding vehicle from a distance and travels at a constant speed, the vehicle decelerates according to the traveling state of the preceding vehicle. However, when the target deceleration rate αe is switched from the target deceleration rate αec to the target deceleration rate αer, the target deceleration rate αe is not suddenly switched from the target deceleration rate αec to the target deceleration rate αer. It is suitably prevented that the passenger feels uncomfortable.
[0061]
Therefore, for example, in a situation where the preceding vehicle is traveling at a constant speed and the own vehicle catches up to the preceding vehicle from a distance, the preceding vehicle acceleration αf, that is, the preceding vehicle deceleration is small, and the weight W1 is 0 or in the vicinity thereof. In addition, since the tracking state counter CNT does not satisfy the above-described conditions, the weight W2 also has a value of 0 or its vicinity. Therefore, in this case, the weight W is set to the value 0 or the vicinity thereof, and the target deceleration rate αe is set mainly based on the target deceleration rate αec.
[0062]
On the other hand, when the own vehicle catches up with the preceding vehicle and enters the tracking state, the tracking state counter CNT starts to be added. In this case, the weight W2 and eventually the weight W gradually increase, and the target deceleration rate αe is set to the target deceleration αe. The deceleration αec gradually shifts to the target deceleration αer. That is, if the tracking state continues to some extent, the target deceleration rate αe is switched in advance so that it is gradually calculated based on the target deceleration rate αer. Therefore, even if the preceding vehicle subsequently decelerates, the target deceleration rate αe is not suddenly switched, and the passenger is preferably prevented from feeling uncomfortable.
[0063]
If the preceding vehicle decelerates immediately after the host vehicle catches up with the preceding vehicle and enters the tracking state, the preceding vehicle acceleration αf decreases to the negative side, that is, the preceding vehicle deceleration increases and the weight W1 gradually increases. Become bigger. Therefore, in this case, the weight W gradually becomes 1 without waiting for the increase in the weight W2, and the target deceleration rate αe is quickly changed to gradually shift from the target deceleration rate αec to the target deceleration rate αer. . Accordingly, even in this case, the target deceleration rate αe is not suddenly switched, and the passenger is preferably prevented from feeling uncomfortable.
[0064]
By the way, the target deceleration rate αe is calculated as described above. In the tracking traveling control, when the target deceleration rate αe is applied to the actual control, the output value of the target deceleration rate αe, that is, the target deceleration rate. Hysteresis is provided between the speed output αe-out and the target deceleration input αe-in.
[0065]
In other words, referring to FIG. 9, there is shown a hysteresis relationship (solid arrow) between the target deceleration output αe-out and the target deceleration input αe-in. As shown in FIG. 9, the target deceleration αe Is increased to a value 1 (K = 1), the target deceleration output αe-out is set to the same value as the target deceleration input αe-in, while the target deceleration αe decreases. When the target deceleration input αe-in is greater than or equal to the predetermined value Xi1, the slope K is 1 (K = 1) but decreases along the offset line, and the target deceleration input αe-in is less than the predetermined value Xi1. In a small range where the target deceleration output αe-out is smaller than the predetermined value Xo1, the slope K decreases along a line having a value K1 (K1> 1, for example, 1.4).
[0066]
As a result, the normal target deceleration input αe-in fluctuates finely due to changes in the behavior of the preceding vehicle, disturbance due to noise in the signal output from the scanning laser radar 2, and the like, especially when the own vehicle approaches the preceding vehicle. However, even if the target deceleration input αe-in varies as described above, the target deceleration output αe-out, that is, the target deceleration αe varies. This is preferably prevented.
[0067]
Returning to FIG. 2, in step S22, it is determined whether or not the own vehicle speed Ve detected in step S12 is higher than a predetermined low vehicle speed Ve0 (for example, 40 km / h). When the determination result is false (No) and the host vehicle speed Ve is equal to or lower than a predetermined low vehicle speed Ve0, the vehicle 1 is generally traveling in the city, and the driver frequently operates the brake pedal 28. It is possible to determine, and the routine is exited without executing the tracking control.
[0068]
On the other hand, if the determination result in step S22 is true (Yes) and the host vehicle speed Ve is greater than the predetermined low vehicle speed Ve0, the process proceeds to step S24.
[0069]
In step S24, it is determined whether or not the own vehicle should be decelerated. That is, it is determined here whether braking control or throttle control should be performed. Specifically, the braking control is performed when the following conditions 1) to 3) are satisfied.
[0070]
1) Tracking control is in progress
2) Vr <0
3) L <La or αer> αer1
That is, in the step S24, the relative speed Vr becomes negative during the tracking travel control, whether the inter-vehicle distance L has interrupted the braking start distance La, or the target deceleration αer of the host vehicle during the preceding vehicle decelerating travel is set in advance. It is determined whether or not the predetermined value αer1 is exceeded.
[0071]
If the determination result in step S24 is false (No) and any of the above conditions is not satisfied, the process proceeds to step S26 and throttle control is performed. The throttle control is to control the throttle actuator 12 according to the running state, but the description thereof is omitted here because it is not directly related to the present invention.
[0072]
On the other hand, if the determination result in step S24 is true (Yes) and it is determined that the above-mentioned conditions are satisfied, the process proceeds to step S28 and brake control is executed (brake control means).
[0073]
In step S28, throttle closing control is performed in executing the braking control. That is, the throttle valve 8 is closed by the throttle actuator 12 to prevent the vehicle 1 from being inadvertently accelerated during braking.
[0074]
In the next step S30, various clip controls are performed. Specifically, in step S28, various clip controls for the target deceleration rate αe, that is, various restriction controls are performed.
[0075]
As the limiting control of the target deceleration rate αe, for example, the limit control for gradually changing the target deceleration rate αe after the driver operates the accelerator pedal (not shown) and overrides (accelerates) during the braking control, and tracking travel switching Immediately after the operation switch 38 is operated and the tracking traveling control is started, the target deceleration αe is gradually changed and immediately after the host vehicle speed Ve becomes equal to or lower than the predetermined low vehicle speed Ve0 (for example, 40 km / h). There are a restriction control for tailing, a restriction control for tailing immediately after the preceding vehicle speed Vf becomes equal to or lower than a predetermined low vehicle speed Vf0, a restriction control when the inter-vehicle distance L is large, and the like. That is, various limiting controls are performed in a situation where the target deceleration rate αe changes rapidly.
[0076]
As a result, a sudden change in the target deceleration rate αe is prevented, and it is eliminated that the vehicle 1 is suddenly decelerated or the decelerating state is suddenly released. Is done. Note that the details of these various restriction controls are omitted here.
[0077]
When the various clip controls are performed and the target deceleration rate αe is appropriately limited by the various limit controls, the process proceeds to step S32.
[0078]
In step S32, the braking force to be generated by the service brake 24 is calculated. Specifically, a braking force capable of generating the target deceleration rate αe obtained as described above is calculated, and a signal value to be supplied to the brake actuator 30 is determined according to the braking force.
[0079]
In step S34, a signal corresponding to the braking force is supplied to the brake actuator 30. As a result, the brake actuator 30 operates properly, and a good and appropriate braking force is generated by the service brake 24.
[0080]
As described above, in the travel control device according to the present invention, when another vehicle suddenly cuts in front of the host vehicle within the range of the braking start distance La, the distance between the other vehicles. According to L, the target inter-vehicle distance Lf is reduced and corrected based on the degree of interruption of the inter-vehicle distance L with respect to the braking start distance La, that is, L / La.
[0081]
Therefore, even when another vehicle suddenly cuts in, the target inter-vehicle distance is temporarily reduced and the target deceleration αer is changed to a small value, so that the host vehicle can be decelerated slowly, and the occupant However, it is possible to realize tracking control without causing a deceleration shock.
[0082]
In the travel control device, the target inter-vehicle distance Lf is reduced according to the inter-vehicle distance L, the target inter-vehicle distance is always present, and the target inter-vehicle distance is controlled as a target.
[0083]
Therefore, it is possible to suitably prevent the host vehicle from inadvertently approaching another vehicle that has been interrupted, thereby ensuring good driving safety.
[0084]
【The invention's effect】
As described above in detail, according to the vehicle travel control device of claim 1, the vehicle speed of the vehicle is controlled by controlling the vehicle speed so that the inter-vehicle distance between the host vehicle and the preceding vehicle becomes the target inter-vehicle distance. In the travel control device, the target deceleration of the host vehicle is calculated based on the relative speed between the host vehicle speed and the preceding vehicle speed, the inter-vehicle distance, and the target inter-vehicle distance, and the braking device is operated and controlled based on the calculated target deceleration. However, the inter-vehicle distance is reduced as in the case where another vehicle has interrupted the vehicle and the preceding vehicle during tracking control. It is set based on either the host vehicle speed or the preceding vehicle speed. When it becomes shorter and shorter than the target inter-vehicle distance, The braking start distance of the host vehicle is set based on the host vehicle speed and the relative speed, and the target inter-vehicle distance is set according to the ratio of the sharply decreasing inter-vehicle distance to the braking start distance. The target deceleration is reduced based on the condensed target inter-vehicle distance.
[0085]
Therefore, even when another vehicle is interrupted, the vehicle can be slowly decelerated so that the passenger does not feel a deceleration shock, and smooth tracking control can be realized.
[0086]
Further, in the travel control device, by always keeping the target inter-vehicle distance in this way, it is possible to suitably prevent the own vehicle from inadvertently approaching another vehicle that has been interrupted. It is possible to ensure sufficient safety.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a travel control device according to the present invention mounted on a vehicle.
FIG. 2 is a flowchart showing a tracking traveling control routine according to the present invention.
FIG. 3 is a flowchart showing a calculation processing routine for a target deceleration rate αe in FIG. 2;
FIG. 4 is a map showing a relationship between a preceding vehicle speed Vf and a target inter-vehicle distance Lf based on the preceding vehicle.
FIG. 5 is a map showing the relationship between the vehicle speed Ve and the braking start distance La.
FIG. 6 is a map showing the relationship between the host vehicle speed Ve and the target inter-vehicle distance Le.
FIG. 7 is a map showing the relationship between preceding vehicle acceleration αf and weight W1.
FIG. 8 is a map showing a relationship between a tracking state counter CNT and a weight W2.
FIG. 9 is a graph showing a hysteresis relationship between a target deceleration output αe-out and a target deceleration input αe-in.
FIG. 10 is a diagram for explaining a target inter-vehicle distance (Lf · L / La) when another vehicle has interrupted between the own vehicle and a preceding vehicle.
FIG. 11 shows own vehicle speed Ve (a) and inter-vehicle distance when control is performed based on the target inter-vehicle distance (Lf · L / La) when another vehicle has interrupted between the own vehicle and the preceding vehicle. It is a time chart which shows the time change of L (b).
[Explanation of symbols]
1 Vehicle (own vehicle)
2 Scanning laser radar
24 Service brake (braking device)
28 Brake pedal
30 Brake actuator
32 Wheel speed sensor
38 Tracking travel switch operation switch
50 Electronic control unit (ECU)

Claims (1)

In a travel control device for a vehicle that controls the speed of the host vehicle so that the inter-vehicle distance between the host vehicle and the preceding vehicle becomes the target inter-vehicle distance, and performs the travel control,
A braking device that automatically applies braking force to the vehicle;
An inter-vehicle distance detecting means for detecting the inter-vehicle distance;
Own vehicle speed detecting means for detecting the own vehicle speed;
Preceding vehicle speed detection means for detecting the preceding vehicle speed;
Target inter-vehicle distance calculation means for calculating the target inter-vehicle distance based only on one of the host vehicle speed and the preceding vehicle speed;
Braking start distance setting means for setting the braking start distance of the host vehicle based on the host vehicle speed and the relative speed ;
Target deceleration calculation means for calculating a target deceleration of the host vehicle based on a relative speed between the host vehicle speed and the preceding vehicle speed, the inter-vehicle distance and the target inter-vehicle distance;
A target inter-vehicle distance reduction means for reducing the target inter-vehicle distance according to a ratio of the sharply reduced inter-vehicle distance to the braking start distance when the inter-vehicle distance is sharply reduced from the target inter-vehicle distance;
Braking control means for controlling the operation of the braking device based on the target deceleration;
A travel control device for a vehicle, comprising:

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