JP4576922B2 - Vehicle travel control device - Google Patents

Description

  The present invention relates to a vehicular travel control device that causes a preceding vehicle to travel following the preceding vehicle while keeping the inter-vehicle distance between the preceding vehicle and the own vehicle at a target inter-vehicle distance.

As a conventional vehicle travel control device, for example, when the host vehicle involves a right or left turn when passing through an intersection, the host vehicle speed is adjusted to a vehicle speed suitable for a right or left turn based on the distance to the intersection and the speed of the preceding vehicle. (For example, refer to Patent Document 1).
In addition, when the relative distance from the object ahead of the vehicle is equal to or less than the predetermined distance or when the target deceleration exceeds the predetermined value, it is determined that the brake preload is required, and when the acceleration operation by the driver is completed, It is known to operate a brake preload that does not feel deceleration (for example, see Patent Document 2). As a result, when an obstacle that is not on the same lane is detected and automatic brake control is performed, it is possible to prevent the driver from feeling uncomfortable and when the driver performs a brake operation. Therefore, it is possible to realize brake control with good initial response.
JP 2001-301484 A JP 2000-309257 A

By the way, when the own vehicle automatically accelerates / decelerates by running control, it is conceivable that the driver does not put his or her foot on the accelerator pedal or the brake pedal. For this reason, a brake with better initial response is required for sudden jumping of pedestrians and bicycles, jumping of oncoming vehicles when traveling at intersections, and the like in a state where the host vehicle is under acceleration control.
However, in the conventional device described in the above-mentioned Patent Document 1, when the own vehicle is accompanied by a right or left turn when passing the intersection, it is only adjusted so that the own vehicle speed becomes an appropriate vehicle speed. There is an unsolved problem that it is not possible to respond appropriately when a brake with good characteristics is required.

Further, in the conventional device described in Patent Document 2, when the host vehicle obviously needs to be decelerated, such as when the relative distance to the front object is small, the brake preload prior to the driver's braking operation is performed. Therefore, there is an unsolved problem that, for example, when a brake with good responsiveness is required when the host vehicle is accelerating following the preceding vehicle, the vehicle cannot be appropriately dealt with.
Accordingly, the present invention has been made paying attention to the unsolved problems of the above-described conventional example, and when the host vehicle is subjected to acceleration control, the vehicle can improve the response of the brake according to the running state. An object of the present invention is to provide a traveling control device for a vehicle.

In order to achieve the above object, the vehicular travel control device according to the present invention, when it is determined that the host vehicle is in a predetermined vehicle travel state and an acceleration command is issued by the vehicle speed control means, Then, the brake actuator is driven and controlled to perform preliminary braking prior to the driver's braking operation.

According to the present invention, when it is determined that the acceleration command is issued by the follow-up running control, the vehicle is accelerated without regard to the driver's intention because the preliminary braking state is set so as not to feel deceleration. Even when a pedestrian or a bicycle suddenly jumps out, the brake with good initial response can be realized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing an embodiment in which the present invention is applied to a rear wheel drive vehicle. In the figure, 1FL and 1FR are front wheels as driven wheels, and 1RL and 1RR are rear wheels as drive wheels. Thus, the driving force of the engine 2 is transmitted to the rear wheels 1RL and 1RR via the automatic transmission 3, the propeller shaft 4, the final reduction gear 5, and the axle 6 to be rotationally driven.

The front wheels 1FL, 1FR and the rear wheels 1RL, 1RR are each provided with a brake actuator 7 composed of, for example, a disc brake that generates a braking force, and the braking hydraulic pressure of these brake actuators 7 is controlled by a braking control device 8. Is done.
Here, the braking control device 8 generates a braking hydraulic pressure in response to depression of a brake pedal (not shown), and also according to a braking pressure command value P ^* and a braking pressure command value Pp ^* from a travel control controller 20 described later. The brake hydraulic pressure is generated and output to the brake actuator 7.

Further, the engine 2 is provided with an engine output control device 9 that controls its output. In this engine output control device 9, a throttle actuator 10 that adjusts a throttle opening provided in the engine 2 in accordance with a depression amount of an accelerator pedal (not shown) and a throttle opening command value θ ^* from a travel control controller 20 described later. Is configured to control. Further, a vehicle speed sensor 13 is provided as vehicle speed detecting means for detecting the own vehicle speed V by detecting the rotational speed of the output shaft provided on the output side of the automatic transmission 3.

On the other hand, a radar system that sweeps laser light and receives reflected light from the preceding vehicle as an inter-vehicle distance detecting means for detecting the inter-vehicle distance between the host vehicle and the preceding vehicle at the lower part of the vehicle body on the front side of the vehicle The inter-vehicle distance sensor 14 is provided.
Further, a traveling control switch 15 is provided in the vicinity of the driver's seat, and this traveling control switch 15 is configured to operate ON / OFF switching of the vehicle traveling control device and setting of the set vehicle speed V _SET. Yes. Then, the traveling control of the host vehicle is performed in the follow-up traveling control mode by turning on the traveling control switch 15.

  In addition, the vehicle body matches the global positioning system (GPS) 16 as a travel point detection means for detecting the travel position of the host vehicle, and the host vehicle position data input from the global positioning system 16. For example, a road map data storage unit 17 is provided as road information providing means configured by, for example, a car navigation system.

  Further, this vehicle is provided with a stroke sensor 18 for detecting a stroke amount ST of an accelerator pedal (not shown) and a steering angle sensor 19 as a steering angle detecting means for detecting a steering angle δ of the steering wheel. It is output to the controller 20 for traveling control. The stroke sensor 18 constitutes an accelerator operation detecting means, and the accelerator depression speed Va can be detected based on the stroke amount ST detected by the stroke sensor 18.

Then, the switch signal SS and the set vehicle speed V _SET output from the travel control switch 17, the own vehicle speed V output from the vehicle speed sensor 13, the inter-vehicle distance D output from the inter-vehicle distance sensor 14, and the global positioning system 16 The vehicle position information output from the road map data storage unit 17, the stroke amount ST output from the stroke sensor 18, and the steering angle δ output from the steering angle sensor 19 are input to the travel control controller 20. When the traveling control controller 20 captures the preceding vehicle, the target vehicle speed is set so that the inter-vehicle distance becomes the target inter-vehicle distance, the own vehicle speed is controlled, and the preceding vehicle is not captured. brake controller 8 and engine output system the braking pressure command value P ^* and the target throttle opening theta ^* is controlled to set vehicle speed V _sET to the vehicle speed V driver set And outputs it to the device 9.

Further, when the vehicle speed is traveling at a low speed or traveling at an intersection, the travel control controller 20 assumes that an interruption of a pedestrian or an oncoming vehicle at the time of traveling at the intersection is estimated in front of the vehicle, and the driver's braking is performed. A braking pressure command value Pp ^* for generating a brake preload Pp as preliminary braking prior to the operation is output to the braking control device 8. Here, the brake preload Pp refers to a very small brake pressure at which the passenger does not feel deceleration.

The travel control controller 20 includes a microcomputer and its peripheral devices, and constitutes a control block shown in FIG. 2 according to the software form of the microcomputer.
This control block includes a relative speed calculation unit 21 that calculates a relative speed ΔV with respect to the preceding vehicle based on the inter-vehicle distance D input from the inter-vehicle distance sensor 14, and a preceding vehicle based on the own vehicle speed V input from the vehicle speed sensor 13. a target inter-vehicle distance calculating section 22 for calculating a target inter-vehicle distance D ^* between the vehicle and the vehicle, the damping coefficient ζ and the natural frequency on the basis of the inter-vehicle distance D and target inter-vehicle distance target inter-vehicle distance calculated by the calculating unit 22 D ^* The inter-vehicle distance command value calculation unit 23 for calculating the inter-vehicle distance command value _DT for making the inter-vehicle distance D coincide with the target inter-vehicle distance D ^* by the reference model using the number ωn, the inter-vehicle distance command value calculation unit 23, the inter-vehicle distance command value calculation unit 23 A target for calculating a target vehicle speed V ^* for making the inter-vehicle distance D coincide with the inter-vehicle distance command value _DT based on the inter-vehicle distance command value D _T calculated in 23 and the relative speed ΔV calculated in the relative speed calculation unit 21. The target vehicle speed V ^* calculated by the target vehicle speed calculation unit 24 or the driver is set according to the detection state of the preceding vehicle by the vehicle speed calculation unit 24 and the inter-vehicle distance sensor 14 and the operation state of the travel control switch 15. The target acceleration / deceleration α ^* that achieves the set vehicle speed V _SET is calculated, and the braking pressure command value P ^* for the braking control device 8 and the throttle opening for the engine output control device 9 are realized so as to realize the target acceleration / deceleration α ^*. And a vehicle speed control unit 25 that outputs a command value θ ^* .

In addition, it is determined whether or not preliminary braking is necessary based on at least the own vehicle speed V and any of the own vehicle position information input from the global positioning system 16 and the road map data storage unit 17, and the necessary preliminary braking occurrence state is determined. The brake preload Pp is set according to the target acceleration / deceleration α ^* calculated by the vehicle speed controller 25 when it is determined that the brake preload Pp is generated, and the brake pressure command value Pp for the brake control device 8 is generated so as to generate the brake preload Pp. A preliminary braking control unit 26 for outputting ^* is provided.

In FIG. 2, a target vehicle speed calculation unit 24 and a vehicle speed control unit 25 correspond to vehicle speed control means.
Here, the relative speed calculation unit 21 is configured by a band-pass filter that performs, for example, a band-pass filter process on the inter-vehicle distance D input from the inter-vehicle distance sensor 14.
The transfer function of this bandpass filter can be expressed by the following equation (1), and since the numerator has a differential term of the Laplace operator s, the relative speed ΔV is approximately differentiated by substantially differentiating the inter-vehicle distance D. Will be calculated.
F (s) = ωc ² s / (s ² + 2ζcωs + ωc ² ) (1)
However, ωc = 2πfc, s is a Laplace operator, and ζc is an attenuation coefficient.

In this way, by using the band pass filter, it is vulnerable to noise and performing tracking control as in the case of calculating the relative speed ΔV by performing a simple differential calculation from the amount of change per unit time of the inter-vehicle distance D. It is possible to avoid the fact that the vehicle behavior is likely to be affected, such as the occurrence of wobbling.
The cut-off frequency fc in the above equation (1) is determined by the magnitude of the noise component included in the inter-vehicle distance D and the allowable value of acceleration fluctuations before and after the vehicle body in a short cycle. In addition, in the calculation of the relative speed ΔV, the differential process may be performed by a high-pass filter that performs a high-pass filter process on the inter-vehicle distance D instead of using a band-pass filter.

Further, the target inter-vehicle distance calculation unit 22 uses the host vehicle speed V and the time T ₀ (inter-vehicle time) until the host vehicle reaches the position D ₀ [m] behind the current preceding vehicle using the following (2 The target inter-vehicle distance D ^* between the preceding vehicle and the host vehicle is calculated according to the formula (1).
D ^* = V × T ₀ + Ds (2)
By adopting this concept of inter-vehicle time, the inter-vehicle distance is set to increase as the host vehicle speed V increases. Here, Ds is the inter-vehicle distance at the time of stop.
As disclosed in Japanese Patent Laid-Open No. 10-81156, the target inter-vehicle distance D ^* may be calculated using the vehicle speed of the preceding vehicle instead of the host vehicle speed.

Further, the inter-vehicle distance command value calculation unit 23 calculates an inter-vehicle distance command value D _T for following traveling while keeping the inter-vehicle distance D at the target value D ^* based on the inter-vehicle distance D and the target inter-vehicle distance D ^*. . Specifically, with respect to the input target inter-vehicle distance D ^* , the following (3) using the damping coefficient ζ and the natural frequency ωn determined to make the response characteristic in the inter-vehicle distance control system the target response characteristic. The inter-vehicle distance command value D _T is calculated by performing a low-pass filter process of the second order lag format according to the reference model G _T (s) expressed by the formula (1).
G _T (s) = ωn ² / (s ² + 2ζωns + ωn) (3)

The target vehicle speed calculation unit 24 calculates the target vehicle speed V ^* using a feedback compensator based on the input inter-vehicle distance command value _DT . Specifically, as shown in the following equation (4), the deviation between the inter-vehicle distance command value _DT and the actual inter-vehicle distance D from the preceding vehicle speed Vt (= V + ΔV) calculated from the own vehicle speed V and the relative speed ΔV. The target vehicle speed V ^* is calculated by subtracting the linear combination of the value obtained by multiplying ΔD (= D _T −D) by the distance control gain fd and the value obtained by multiplying the relative speed ΔV by the vehicle speed control gain fv.
V ^* = Vt− {fd (D _T −D) + fv · ΔV} (4)

The vehicle speed control unit 25 determines whether or not a preceding vehicle exists ahead of the host vehicle based on the inter-vehicle distance D. When there is no preceding vehicle, a preset set vehicle speed V _SET is set as the selected target vehicle speed Vs ^*. and, when the preceding vehicle is present to set a smaller set vehicle speed V _sET or the inputted target vehicle speed V ^* as the selected target vehicle speed Vs ^*.
Then, based on the set selected target vehicle speed Vs ^* and own vehicle speed V, the target acceleration / deceleration α ^* is calculated according to the following equation (5). Here, k is a coefficient.
α ^* = k · (Vs ^* −V) (5)

The target braking / driving force F _OR (= α ^* · M) is calculated by multiplying the target acceleration / deceleration α ^* thus calculated by the vehicle mass M, and a braking pressure command is calculated based on the target braking / driving force F _OR. A value P ^* and a throttle opening command value θ ^* are calculated. Then, the braking pressure command value P ^* is output to the braking control device 8 and the throttle opening command value θ ^* is output to the engine output control device 9, respectively.
Further, the preliminary braking control unit 26 executes the preliminary braking control process shown in FIG. 3 and outputs a braking pressure command value Pp ^* for the braking control device 8.

Next, the preliminary braking control process executed by the preliminary braking control unit 26 of the travel control controller 20 will be described with reference to the flowchart of FIG.
This preliminary braking control process is executed as a timer interrupt process for every predetermined time (for example, 10 msec). First, in step S1, signals from various sensors are read. Specifically, the switch signal SS of the travel control switch 15, the target acceleration / deceleration α ^* , the host vehicle speed V, the accelerator pedal stroke amount ST, and the steering angle δ are read.

Next, in step S2, it is determined whether or not the following traveling control mode is in progress. This determination is made based on whether or not the switch signal SS of the travel control switch 15 disposed in the vicinity of the driver's seat is in the on state. When the switch signal SS of the travel control switch 15 is in the on state, the follow travel control mode is set. It judges that it is in, and transfers to step S3.
On the other hand, when the result of determination in step S2 is that the switch signal SS of the travel control switch 15 is in the OFF state and not in the follow-up travel control mode, the timer interrupt process is terminated and the process returns to the predetermined main program.

Next, in step S3, it is determined whether or not the _host vehicle speed V read in step S1 is equal to or lower than a predetermined vehicle speed threshold value _VTH . If V> _VTH , the process _proceeds to step S6, which will be described later, and V≤ When it is V _TH , the process proceeds to step S4.
Here, the vehicle speed threshold V _TH is set to a vehicle speed (for example, about 10 km / h) such that a pedestrian, a bicycle, or the like does not pass through between the vehicles. That is, when V ≦ V _TH , it can be determined that the host vehicle is traveling at a low speed and that a pedestrian, a bicycle, or the like may cross the front of the host vehicle.

In step S4, it is determined whether or not the driving force control by the follow-up running control is being performed. This determination is made based on the sign of the target acceleration / deceleration α ^* read in step S1, and when α ^* > 0, the throttle opening command value θ ^* for accelerating the host vehicle is the engine output control device. 9 is determined, it is determined that the driving force control by the follow-up running control is being performed and the acceleration command is issued, and the process proceeds to step S5.
Further, when α ^* ≦ 0, a braking pressure command value P ^* for decelerating the host vehicle is output to the braking control device 8, and the braking command is being controlled by the follow-up traveling control and the acceleration command is It judges that it has not been taken out and shifts to step S8 which will be described later.

In step S <b> 5, the brake preload Pp generated in the host vehicle is calculated and stored in the memory in the travel control controller 20. The brake preload Pp is calculated based on the target acceleration / deceleration α ^* with reference to the brake preload calculation map shown in FIG. Further, the brake preload is calculated for each sampling period in the flowchart shown in FIG. 3, and the value stored in the memory is updated. Here, the brake preload calculation map has the target acceleration / deceleration α ^{* on} the horizontal axis and the brake preload Pp on the vertical axis, and the brake preload Pp has a certain minimum value Pp in a region where the target acceleration / deceleration α ^* is relatively small. It is set to be _m . Thereafter in proportion to the increase of the target acceleration alpha ^* also increases brake preload Pp, the target acceleration alpha ^* is relatively large region is set to be constant maximum value Pp _M. Here, the maximum value Pp _M is set to the maximum brake pressure at which the occupant does not feel deceleration.

Thus, by setting the brake preload Pp in accordance with the target acceleration / deceleration α ^* , it is possible to take into account the difference in the idling distance due to the difference in acceleration / deceleration. It is possible to appropriately cope with a scene where there is a high possibility that a brake with good responsiveness is required, such as setting the preload Pp to be large to improve the responsiveness of the brake.

Next, the process proceeds to step S6, where it is determined whether or not the _host vehicle speed V exceeds the vehicle speed threshold value V _TH or an accelerator operation by the driver is detected. When V> V _TH , it is very unlikely that a pedestrian, a bicycle, or the like will cross the front of the vehicle, so it can be determined that it is not necessary to generate the brake preload Pp.
Further, when the accelerator operation by the driver is detected, it can be determined that it is not necessary to generate the brake preload Pp because the driver is intentionally accelerating. Further, at this time, the driver is at least put his feet on the accelerator pedal, and even when a pedestrian or the like encounters jumping out, the driver can shift to the brake operation relatively quickly. It can be determined that it is not necessary to generate them.

When V> V _TH or an accelerator operation is detected, the process proceeds to step S7. When V ≦ V _TH and the accelerator operation is not detected, the process proceeds to step S9 described later.
In step S7, it is determined whether or not the driver is performing a sudden accelerator operation or a sudden steering operation. Here, the determination as to whether or not a sudden accelerator operation is being performed is performed based on the accelerator depression speed Va calculated based on the stroke amount ST detected by the stroke sensor 18 provided in the accelerator pedal. when the accelerator depression speed Va exceeds a preset depression speed threshold Va _TH, it is determined that sudden acceleration operation is performed. The depression speed threshold value Va _TH is set by experimentally obtaining the brake depression speed in an emergency, and is set to 90 deg / s, for example.

When the driver is suddenly operating the accelerator, there is a possibility that he / she accidentally stepped on the accelerator pedal even though he wanted to brake suddenly to avoid contact with obstacles ahead of the vehicle It is determined that it is necessary to continue to generate the brake preload Pp.
Here, the case where the value of the stepping speed threshold value Va _TH is made constant has been described, but the present invention is not limited to this, and the value may be changed according to the vehicle speed V, for example.

Similarly, whether or not a sudden steering operation is being performed is determined based on the steering angle δ detected by the steering angle sensor 19, and is obtained by, for example, time differentiation of a change in the steering angle δ. When the steering angular velocity to be exceeded exceeds a preset steering angle threshold value _δTH , it is determined that a sudden steering operation is being performed. Here, the steering angle threshold value δ _TH can be set by experimentally obtaining the steering angle change amount in an emergency.

Note that a torque sensor that detects the steering torque may be provided instead of the steering angle sensor 19, and the steering angular velocity may be detected by time differentiation of the detected torque sensor value.
When a sudden steering operation is performed by the driver, it is determined that there is a possibility of emergency braking because sudden steering is being performed to avoid an obstacle ahead of the host vehicle, and a brake preload Pp is generated. Judge that it is necessary to continue.
In step S8, the brake preload Pp is set to zero (0). As a result, the brake preload generation state can be substantially canceled.
Next, the process proceeds to step S9, where the braking pressure command value Pp ^* for generating the brake preload Pp set in step S5 or step S8 is calculated, and this braking pressure command value Pp ^* is sent to the braking control device 8. Output, end the timer interrupt process, and return to the predetermined main program.

Therefore, it is assumed that the host vehicle is traveling with the traveling control switch 15 turned off. In this case, since the follow-up traveling control process is in the non-control state, the preliminary braking control process in FIG. 3 is terminated by the determination in step S2, and the normal driving according to the driver's accelerator and brake operation is completed. Continue on the street.
When the travel control switch 15 is turned on from this normal travel state, the follow-up travel control process is started. When the preceding vehicle is detected, the target vehicle speed V is set such that the inter-vehicle distance D with the preceding vehicle becomes the target inter-vehicle distance D ^{*. The} braking pressure command value P ^* and the target throttle opening degree θ ^* for controlling the host vehicle speed V by setting ^* are output to the braking control device 8 and the engine output control device 9 to shift to the following traveling control.

At this time, when the host vehicle accelerates following the preceding vehicle and the host vehicle speed V exceeds a predetermined speed threshold value V _TH , the process proceeds from step S3 to step S6 in FIG. 3, and V> V _TH . The process proceeds to step S7. If it is assumed that neither the accelerator operation nor the steering operation is performed by the driver, both the accelerator operation and the steering operation are determined to be normal operations without requiring urgency, so that the determination in step S7 returns to step S8. The process proceeds to set the brake preload Pp to zero. Accordingly, the follow-up traveling control according to the inter-vehicle distance D is continued without generating the brake preload Pp.

Further, it is assumed that the host vehicle is traveling at a low speed equal to or less than the speed threshold V _TH following the preceding vehicle, and the host vehicle is also accelerating in accordance with the acceleration of the preceding vehicle. In this case, since V ≦ V _TH , the process proceeds from step S3 to step S4, and since the acceleration command is issued to the host vehicle, the process proceeds from step S4 to step S5 to calculate the brake preload shown in FIG. The brake preload Pp corresponding to the target acceleration / deceleration α ^* is calculated with reference to the map. Assuming that the driver does not perform the accelerator operation, the process proceeds from step S6 to step S9, and the braking pressure command value Pp ^* for generating the brake preload Pp calculated in step S5 is sent to the braking control device 8. Are output. As a result, a brake pressure that does not cause the passenger to feel the deceleration is generated, and the response of the brake is improved.

In this way, when the host vehicle is accelerated by the driving force control of the following traveling control while traveling at a low speed, the brake preload is generated to improve the response of the brake, so that pedestrians and bicycles can cross the road. Therefore, stable vehicle behavior can be realized when passing between the host vehicle and the preceding vehicle or when suddenly jumping out.
Thereafter, when the own vehicle accelerates following the preceding vehicle and the own vehicle speed V exceeds the speed threshold V _TH , the process proceeds from step S3 to step S6. Since V> V _TH , the process _proceeds to step S7 according to the determination in step S6. If it is assumed that the accelerator and steering operation are not performed by the driver at this time, the process proceeds to step S8 and the brake preload Pp is set to zero. The Then, the brake preload Pp is zero, that is, the brake pressure command value Pp ^* for releasing the brake preload generation state is output to the brake control device 8, and the normal follow-up running control is shifted to without generating the brake preload Pp. To do.

On the other hand, it is assumed that the driver's sudden steering is performed in a state where the _host vehicle accelerates following the preceding vehicle and the host vehicle speed V exceeds the speed threshold V _TH . In this case, it is determined No in step S7, and the process proceeds to step S9. Then, the brake pressure command value Pp ^* for generating the brake preload Pp calculated in the previous sampling process is output to the brake control device 8, thereby continuing the brake preload generation state. At this time, when the brake preload Pp calculated in the previous sampling process is not stored in the memory, for example, the maximum brake preload Pp _M shown in FIG. 4 is given.

Thus, even when the host vehicle speed V exceeds the speed threshold value _VTH , when the driver is steering rapidly, an obstacle ahead of the host vehicle is avoided. Since it is determined that there is a possibility of sudden braking, the brake preload Pp continues to be generated, and therefore it is possible to appropriately cope with a scene where a brake with good response is required.
Further, it is assumed that the host vehicle is following following at a low speed equal to or less than the speed threshold value V _TH and is in a brake preload generation state. Assuming that the accelerator operation is performed by the driver at this time, the brake preload Pp corresponding to the target acceleration / deceleration α ^* is calculated in step S5, and then the process proceeds to step S7 by the determination in step S6.

When the accelerator operation by the driver is a normal operation, the process proceeds to step S8 based on the determination in step S7, and the brake preload Pp is set to zero. Then, the brake preload Pp is set to zero, that is, a braking pressure command value Pp ^* for releasing the brake preload generation state is output to the brake control device 8 in accordance with the accelerator operation by the driver without generating the brake preload Pp. Transition to running.

On the other hand, it is assumed that the _host vehicle is following following at a low speed equal to or less than the speed threshold value V _TH and is in a brake preload generation state, and a sudden accelerator operation is performed by the driver. In this case, the brake preload Pp corresponding to the target acceleration / deceleration α ^* is calculated in step S5, and then the process proceeds to step S7 based on the determination in step S6. And it determines with No by step S7, transfers to step S9, and the braking pressure command value Pp ^* for generating the brake preload Pp calculated by said step S5 is output with respect to the braking control apparatus 8, Continue to generate brake preload.

  As described above, when the normal accelerator operation by the driver is detected in the brake preload generation state, the brake preload generation state is canceled, but when the sudden accelerator operation is detected, the accelerator pedal and the brake pedal are erroneously pressed. The brake preload generation state is continued in consideration of the vehicle, so that when the driver is performing normal accelerator operation, vehicle behavior that matches the driver's intention to accelerate can be realized, and sudden accelerator operation can be performed. Can respond appropriately in situations where a brake with good response is required.

Therefore, in the first embodiment, when the host vehicle is controlled in driving force during follow-up, the brake preload is generated so as not to feel deceleration. Therefore, it is possible to respond appropriately and to realize a stable vehicle behavior.
Also, when the host vehicle is driving force controlled when the host vehicle speed is lower than the vehicle speed threshold, a brake preload is generated, so that the pedestrian or the like tries to cross the road because the host vehicle is stopped or traveling at a low speed. When a brake with good response is required, such as when the vehicle passes through between the host vehicle and the preceding vehicle, the vehicle can appropriately cope with it, and a stable vehicle behavior can be realized.

Furthermore, when the vehicle speed exceeds the vehicle speed threshold, the brake preload is set to zero and the brake preload generation state is released, so the vehicle speed has reached a vehicle speed at which pedestrians etc. have not passed through between the vehicles. Therefore, appropriate brake preload generation control according to the possibility of emergency braking can be performed.
In addition, when accelerator operation by the driver is detected when the brake preload is generated, the brake preload is set to zero and the brake preload generation state is released, so that the driver immediately shifts to the acceleration state intended by the driver. The vehicle behavior that matches the driver's intention can be realized.

  Furthermore, when a sudden accelerator operation by the driver is detected when the brake preload is generated, the brake preload generation state is maintained without being released. Appropriately respond to situations where a highly responsive brake is required, taking into account the accidental depression of the accelerator pedal, despite the fact that he wanted to avoid sudden contact with the vehicle. Can do.

  In addition, when a sudden steering operation by the driver is detected when the brake preload is generated, the brake preload generation state is maintained without being released. For example, a pedestrian or the like appears in front of the vehicle. Thus, it is possible to appropriately cope with a situation where a brake with good response is required in consideration of the possibility of emergency braking, assuming a case where the vehicle is suddenly steered to avoid this.

Furthermore, the greater the target acceleration / deceleration, the greater the brake preload is calculated, so it is possible to take into account the difference in the free running distance due to the difference in acceleration, and the appropriate brake according to the possibility of requiring a responsive brake A preload can be generated.
In the first embodiment, the case where the brake preload is calculated based on the target acceleration / deceleration with reference to the brake preload calculation map shown in FIG. 4 is described. However, the present invention is not limited to this. The brake preload Pp may be calculated based on the inter-vehicle distance D with the preceding vehicle and the speed Vt of the preceding vehicle.

When the brake preload Pp is calculated based on the inter-vehicle distance D, the brake preload calculation map shown in FIG. 5 is referred to. In this brake preload calculation map, the horizontal axis represents the inter-vehicle distance D, and the vertical axis represents the brake preload Pp. The brake preload Pp is set to have a constant maximum value Pp _{M in} a region where the inter-vehicle distance D is relatively small. Has been. Thereafter brake preload Pp decreases with increasing inter-vehicle distance D, the relatively large area vehicle distance D is set to be a constant minimum value Pp _m.

Further, when the brake preload Pp is calculated based on the preceding vehicle speed Vt, the brake preload calculation map shown in FIG. 6 is referred to. The brake preload calculation map, preceding vehicle speed Vt on the horizontal axis, and taking a brake preload Pp on the vertical axis, brake preload Pp is set as the preceding vehicle speed Vt is a constant minimum value Pp _m is a relatively small area Has been. Then, as the preceding vehicle speed Vt increases, the brake preload Pp also increases, and is set to a constant maximum value Pp _{M in} a region where the preceding vehicle speed Vt is relatively large.

Thus, since the brake preload is calculated to be larger as the inter-vehicle distance from the preceding vehicle is smaller, the difference in the idling distance due to the difference in inter-vehicle distance can be taken into account, and there is a possibility that a responsive brake is required. Accordingly, it is possible to generate an appropriate brake preload.
In addition, the greater the speed of the preceding vehicle, the larger the brake preload is calculated, so it is possible to take into account the difference in the free running distance due to the difference in the preceding vehicle speed, and it is appropriate according to the possibility that a brake with good response is required. It is possible to generate a brake preload.

Furthermore, in the first embodiment, the brake preload calculation process in step S5 of FIG. 3 is performed by referring to the brake preload calculation maps shown in FIGS. The final brake preload may be set by selecting a value).
That is, the brake preload to be calculated according to the target acceleration alpha ^* Pp _a, a brake preload calculated according to the following distance D Pp _D, the brake preload to be calculated in accordance with the preceding vehicle speed Vt When Pp _Vr The brake preload Pp generated in the host vehicle may be calculated based on the following equation (6).
_{Pp = max (Pp a, Pp} D, Pp Vr) ......... (6)
Here, max () is a function that performs a select high on the value in parentheses.

  In the first embodiment, the case where the brake preload generation state is simply maintained when a sudden accelerator operation by the driver is detected or when a sudden steering operation by the driver is detected has been described. However, the present invention is not limited to this, and the brake preload may be corrected to increase. Thereby, acceleration can be blunted and the response of the brake to emergency braking can be further improved.

Next, a second embodiment of the present invention will be described.
In the second embodiment, a brake preload is generated when the host vehicle is traveling in a predetermined range near the intersection and in the vicinity of the intersection, and the host vehicle is under acceleration control by the follow-up travel control. .
FIG. 7 is a flowchart showing a preliminary braking control process executed by the preliminary braking control unit of the follow-up control controller 20 in the second embodiment, and the preliminary braking control process of FIG. 3 in the first embodiment described above. In step S3, the process of step S3 is replaced with step S21 for determining whether or not the host vehicle is traveling within a predetermined range near the intersection and the intersection, and the process of step S6 is a predetermined step near the intersection and the intersection. Except that it is replaced with step S22 that determines whether or not the vehicle has passed the range or the accelerator operation by the driver is detected, the same processing as in FIG. Are denoted by the same reference numerals, and detailed description thereof is omitted.

  That is, when it is determined Yes in step S2, the process proceeds to step S21, and it is determined whether or not the vehicle is traveling within a predetermined range near the intersection and the intersection. This determination is performed by the car navigation system, the host vehicle travel point data input from the global positioning system 16 is read, and then the road map data storage unit 17 is accessed based on the host vehicle travel point data. It is determined whether or not the current travel point is within a predetermined range near the intersection and the intersection.

Here, the predetermined range is indicated by the hatched portion in FIG. 8, and it is assumed that a predetermined distance L is added to the range formed by connecting the corners C1 to C4 at the intersection. The predetermined distance L is, for example, the length in the front-rear direction for one vehicle. The predetermined distance L may be changed according to the size of the intersection and the vehicle speed V.
When it is determined that the determination result of step S21 is that the host vehicle is traveling within the predetermined range, the process proceeds to step S4, and when it is determined that the vehicle is traveling outside the predetermined range, step S22 is performed. Migrate to

  In step S22, it is determined whether the host vehicle has passed through the intersection and a predetermined range in the vicinity of the intersection, or whether an accelerator operation by the driver is detected. When the host vehicle is traveling within an intersection and within a predetermined range near the intersection, not only pedestrians and bicycles jump out, but also an opposite right turn car when the host vehicle is traveling straight (or when the host vehicle is turning right) Therefore, it is determined that it is necessary to generate the brake preload Pp. On the other hand, when the host vehicle is traveling outside the predetermined range, it is determined that there is no need to generate the brake preload Pp because the possibility of encountering an oncoming vehicle or the like is extremely low.

In the process of FIG. 7, the process of step S21 corresponds to the intersection detection means.
Therefore, it is assumed that the host vehicle is currently following the preceding vehicle outside a predetermined range before the intersection. In this case, the process proceeds to step S7 via step S22 based on the determination in step S21 of FIG. If it is assumed that neither the accelerator operation nor the steering operation is performed by the driver, both the accelerator operation and the steering operation are determined to be normal operations without requiring urgency, so that the determination in step S7 returns to step S8. The process proceeds to set the brake preload Pp to zero. Accordingly, the follow-up traveling control according to the inter-vehicle distance D is continued without generating the brake preload Pp.

Thereafter, if the host vehicle enters the intersection and a predetermined range near the intersection and is going to accelerate following the preceding vehicle while traveling straight, the process proceeds from step S21 to step S5 to step S5, and FIG. The brake preload Pp corresponding to the target acceleration / deceleration α ^* is calculated with reference to the brake preload calculation map shown in FIG. Assuming that the driver does not perform the accelerator operation, the process proceeds from step S22 to step S9, and the braking pressure command value Pp ^* for generating the brake preload Pp calculated in step S5 is sent to the braking control device 8. Are output. As a result, a brake pressure that does not cause the passenger to feel the deceleration is generated, and the response of the brake is improved.

As described above, when the host vehicle is traveling within a predetermined range near the intersection and the intersection and accelerates following the preceding vehicle, the preliminary braking Pp is generated to improve the response of the brake. Stable vehicle behavior can be realized with respect to, for example, jumping out of an opposite right turn car when the host vehicle is traveling straight at an intersection.
Thereafter, when the host vehicle passes through the intersection and a predetermined range near the intersection, the process proceeds from step S21 to step S7 via step S22. If it is assumed that the driver does not perform a sudden accelerator operation or a sudden steering operation, the process proceeds to step S8 based on the determination in step S7, and the brake preload Pp is set to zero. As a result, the brake preload generation state is released, and the normal follow-up running control is restored.

  As described above, in the second embodiment, when the host vehicle is driving within the predetermined range near the intersection and the intersection, the brake preload is generated when the host vehicle is controlled in driving force. When an oncoming right turn vehicle jumps out, or when an oncoming straight vehicle jumps out at the time of a right turn, etc., it is possible to respond appropriately and to achieve stable vehicle behavior.

Furthermore, when the host vehicle passes through the intersection and a predetermined range in the vicinity of the intersection, the brake preload is set to zero and the brake preload generation state is released, so it is determined that there is no need to worry about the oncoming vehicle jumping out at the intersection. Therefore, appropriate brake generation control according to the possibility of emergency braking can be performed.
In the second embodiment, the case where the brake preload is calculated based on the target acceleration / deceleration has been described. However, the present invention is not limited to this, and the brake preload Pp is calculated based on the size of the intersection. You may make it calculate. In this case, the size of the intersection is determined by detecting the number of lanes and the like by the navigation system, and the brake preload Pp is set to be larger as the size of the intersection is larger. Accordingly, it is possible to appropriately cope with a case where there is a high possibility that a brake with good response is required.

  In each of the above embodiments, the case where the brake preload is calculated based on the target acceleration / deceleration has been described. However, the present invention is not limited to this, and the brake preload Pp is calculated based on the brightness of the traveling road. You may make it do. In this case, for example, a light ON / OFF signal is acquired, and it is determined that the road is dark when the light is on, and the road is bright when the light is off, or an external recognition sensor such as a CCD camera. And the brightness may be determined from the captured image. Then, by setting the brake preload Pp to be larger as the brightness of the traveling road is darker, it is possible to appropriately cope with a case where there is a high possibility that a brake with good response is required.

  Further, in each of the above embodiments, the case has been described in which when determining whether or not the brake preload needs to be generated, the vehicle speed determination in step S3 in FIG. 3 and the intersection travel determination in step S21 in FIG. 7 are individually performed. However, the present invention is not limited to this, and these determinations are made at the same time, and the brake preload required when the host vehicle speed is equal to or lower than the predetermined vehicle speed threshold or the host vehicle is traveling in the predetermined range near the intersection and the intersection You may make it judge that it is a generation | occurrence | production state.

It is a schematic structure figure showing an embodiment of the present invention. It is a block diagram which shows the specific example of the controller for driving control of FIG. It is a flowchart which shows the preliminary | backup braking control process performed by the preliminary | backup braking control part of the controller for driving | running | working control of FIG. It is a brake preload calculation map based on target acceleration / deceleration. It is a brake preload calculation map based on the inter-vehicle distance. It is a brake preload calculation map based on the preceding vehicle speed. It is a flowchart which shows the preliminary brake control process performed in the preliminary brake control part in 2nd Embodiment. It is a figure explaining the predetermined range of the intersection and the intersection vicinity.

Explanation of symbols

1FL to 1RR Wheel 2 Engine 3 Automatic transmission 7 Disc brake 8 Braking control device 9 Engine output control device 13 Vehicle speed sensor 14 Inter-vehicle distance sensor 15 Travel control switch 16 Global positioning system 17 Road map data storage unit 18 Stroke sensor 19 Steering angle Sensor 20 Controller for traveling control 25 Vehicle speed control unit 26 Preliminary braking control unit

Claims (11)

Own vehicle speed detecting means for detecting the vehicle speed of the own vehicle;
An inter-vehicle distance detecting means for detecting an inter-vehicle distance with a vehicle subject to follow-up control in front of the host vehicle;
In a vehicle travel control device comprising vehicle speed control means for controlling the braking / driving force of the host vehicle so that the inter-vehicle distance becomes a target inter-vehicle distance,
When the host vehicle is in a predetermined vehicle running state and when it is determined that an acceleration command is issued by the vehicle speed control means, the brake actuator is driven and controlled to perform preliminary braking prior to the driver's braking operation. A vehicular travel control device comprising means.   2. The vehicle travel control apparatus according to claim 1, wherein the predetermined vehicle travel state is a state in which the vehicle speed detected by the own vehicle speed detection means is equal to or lower than a predetermined vehicle speed.   Travel point detection means for detecting a travel point of the host vehicle, road information providing means having road information on which the host vehicle travels, a travel point detected by the travel point detection means, and a road provided by the road information provision means Intersection detection means for detecting that the own vehicle is traveling in the vicinity of the intersection and a predetermined intersection based on the information, and the predetermined vehicle running state is determined by the intersection detection means when the own vehicle is The vehicle travel control device according to claim 1 or 2, wherein the vehicle travel control device is in a state where it is detected that the vehicle is traveling within a predetermined range.   The pre-brake generation unit cancels the pre-brake state when it is determined that the vehicle speed detected by the own vehicle speed detection unit exceeds a predetermined vehicle speed in the pre-braking state. The vehicle travel control device according to 2.   The preliminary braking generating means cancels the preliminary braking state when it is determined that the host vehicle is traveling outside the predetermined range based on the detection result of the intersection detection means in the preliminary braking state. The vehicle travel control apparatus according to claim 3.   Accelerator operation detecting means for detecting an accelerator operation by a driver, and when the preliminary brake generating means detects the accelerator operation by the accelerator operation detecting means when in the preliminary brake state, the preliminary brake state is displayed. The vehicle travel control device according to claim 1, wherein the vehicle travel control device is canceled.   The vehicle according to claim 6, wherein the preliminary braking generation unit maintains the preliminary braking state when the accelerator operation detecting unit detects a sudden accelerator operation in the preliminary braking state. Travel control device.   Steering angle detecting means for detecting a steering angle of the steering wheel, and the preliminary braking generating means detects the sudden steering angle change when the steering angle detecting means detects a sudden steering angle change in the preliminary braking state. The vehicular travel control device according to claim 1, wherein the braking state is maintained. 2. The vehicular travel control apparatus according to claim 1, wherein the preliminary braking generation unit sets a larger preliminary braking state as the inter-vehicle distance detected by the inter-vehicle distance detection unit decreases. The vehicular travel control apparatus according to claim 1, wherein the preliminary braking generation unit sets a larger preliminary braking state as the vehicle speed of the vehicle to be tracked control increases. Road environment detecting means for detecting the state of the road environment ahead of the host vehicle, wherein the preliminary braking generating means is set to a preliminary braking state having a magnitude corresponding to the road environment detected by the road environment detecting means. The vehicle travel control apparatus according to claim 1, wherein

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