JP3728985B2 - Vehicle travel control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle travel control device that includes an inter-vehicle distance control unit that detects an inter-vehicle distance from a preceding vehicle and controls the speed of the host vehicle so as to maintain the detected inter-vehicle distance at a predetermined target inter-vehicle distance.
[0002]
[Prior art]
Conventionally, a constant speed traveling device is known as one of the traveling control devices, and by setting a target vehicle speed, acceleration / deceleration is controlled so that the vehicle speed automatically approaches the target vehicle speed. Furthermore, a traveling control device in which an inter-vehicle distance control function is added to this constant speed traveling device is also known. In this travel control device, for example, the relative speed with respect to the preceding vehicle and the inter-vehicle distance are detected by a laser radar that sweeps the laser to a predetermined range ahead. Then, based on the detected relative distance, a target inter-vehicle distance is set, and acceleration / deceleration is controlled so that the inter-vehicle distance approaches the target inter-vehicle distance.
[0003]
This allows the vehicle speed to be maintained at the target vehicle speed if there is no preceding vehicle, and if there is a preceding vehicle, the distance between the preceding vehicle and the preceding vehicle can be automatically maintained appropriately. Can be reduced.
[0004]
[Problems to be solved by the invention]
Here, whether or not automatic traveling by such a traveling control device is performed is performed by operating a set switch by a driver or the like. When the driver performs an accelerator operation or a brake operation, the vehicle returns to normal driving based on the driver's operation. That is, a normal traveling mode for controlling acceleration / deceleration based on the driver's operation and an automatic traveling mode by the inter-vehicle distance control means are switched based on the driver's operation. In the normal case, when the accelerator is operated while the automatic travel mode is set, the normal travel mode is entered during the accelerator operation, and the automatic travel mode is automatically restored when the accelerator operation is lost. On the other hand, when the brake is operated in a state where the automatic travel mode is set, the mode is changed to the normal travel mode, and the automatic travel mode is not automatically returned even when the brake operation is lost.
[0005]
However, the change in the control contents accompanying the mode switching may cause the driver to feel uncomfortable. For example, even if the vehicle accelerates until it approaches the preceding vehicle and shifts to the automatic travel mode with that speed as the target vehicle speed, or when it accelerates by preparing to step on the brake, it will immediately perform deceleration control and warning. Occurrence occurs. Since the driver has approached the preceding vehicle to some extent by his / her own intention, there is a sense of incongruity in such deceleration control and warning generation.
[0006]
In the automatic travel mode, if the accelerator pedal is depressed during the downshift control, the normal travel mode is entered, and immediately after the downshift control is canceled, the upshift is performed. As described above, there is a problem that a shock occurs when the load on the engine and the shift up due to depression of the accelerator occur at the same time, resulting in poor drive feeling.
[0007]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle travel control device that can prevent an inappropriate operation during mode switching.
[0008]
[Means for Solving the Problems]
  The present invention provides a vehicle travel control device having a detection means for detecting a relative relationship with a preceding vehicle and a control means for controlling the speed of the host vehicle based on the detected relative relationship, based on a driver's operation. A normal driving mode for controlling deceleration and an automatic driving mode for controlling the vehicle speed by the control means, and immediately after the mode is switched between the normal driving mode and the automatic driving mode, Change vehicle speed controller operating conditionsThe
[0009]
Immediately after the switching of the driving mode, due to the difference in the driving type in each driving mode, the transition cannot be performed smoothly, and the driving tends to be uncomfortable for the driver. Immediately after the mode is switched, the operating conditions of the vehicle speed control device are changed, so that inappropriate control at the time of transition can be prevented, and the driver can travel without a sense of incongruity.
[0010]
  Also, ThroughImmediately after switching from the normal travel mode to the automatic travel mode by the device, even if the vehicle speed control content based on the relative relationship with the preceding vehicle is deceleration control, at leastbrakeDo not operate for a predetermined timeYes.Discomfort can be reduced by eliminating deceleration immediately after mode switching. In addition, such a driving without a sense of incongruity is a preferable driving for the following vehicle. However, since the throttle valve opening / closing control in accordance with the accelerator operation is performed, when the driver releases the accelerator, the throttle valve is decelerated by driving in the closing direction. However, this deceleration does not give the driver a sense of incongruity.
[0011]
  AndWhen the distance from the preceding vehicle is closer than a predetermined distance,brakeOperated aboutTheFor example, if the reduction in the inter-vehicle distance cannot be prevented only by deceleration by driving the throttle valve in the closing direction,brakeMake it workAndThe distance from the preceding vehicle can be maintained.
[0012]
Further, the acceleration / deceleration operation control condition can be changed so that the driver does not shift up for a predetermined time when the driver depresses the accelerator and accelerates to shift from the automatic travel mode to the normal travel mode. By configuring in this way, a large shock may occur if the engine torque increases due to the depression of the accelerator and the upshifts overlap at that time, but the shift is delayed until the engine torque stabilizes. Can be done up.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.
[0014]
"overall structure"
FIG. 1 is a block diagram illustrating an overall configuration of a vehicle travel control device according to an embodiment. The laser radar device 10 is attached to a bumper of a vehicle, for example, irradiates laser light toward the front of the vehicle, and receives reflected light from a preceding vehicle.
[0015]
For example, a laser diode is pulse-driven, and pulse laser light is output therefrom. Then, the pulse laser beam is repeatedly scanned in a predetermined range (left and right direction) in front of the vehicle by a rotating polygon mirror. Further, the pulse laser beam is also scanned in the vertical direction by changing the inclination angle of each surface of the polygon mirror.
[0016]
On the other hand, the pulse laser beam reflected by the preceding vehicle is received by a photodiode and converted into an electric signal. Then, the time is measured from when the pulse laser beam is output until the reflected light is received, and the inter-vehicle distance from the preceding vehicle is measured. Further, the relative speed is measured from the time change of the inter-vehicle distance. The laser radar device 10 also detects information on the preceding vehicle such as the positional relationship of the preceding vehicle with respect to the own lane.
[0017]
An example of the configuration of the laser radar device 10 is shown in Japanese Patent Application Laid-Open No. 11-42956. Further, instead of the laser radar device 10, other types of radar such as a millimeter wave radar can be used. The relative velocity can also be measured by detecting the Doppler shift in the transmission / reception wave.
[0018]
The inter-vehicle distance and relative speed measured in the laser radar device 10 are supplied to the inter-vehicle control ECU 12. The inter-vehicle control ECU 12 sets the target inter-vehicle distance according to the relative speed, the inter-vehicle distance, etc. supplied from the laser radar device 10, and compares the detected inter-vehicle distance with the detected current inter-vehicle distance, and the target acceleration / deceleration, shift down request, brake request Generate instructions such as Note that vehicle information detected by other sensors such as the current vehicle speed is also taken into consideration.
[0019]
Instructions such as target acceleration / deceleration, shift down request, and brake request from the inter-vehicle control ECU 12 are supplied to the engine ECU 14. The engine ECU 14 is connected to a VSC ECU 22 that controls the electronic throttle 16, the shift control unit 18, the brake actuator 20, and the like, and the engine ECU 14 controls them. The electronic throttle 16 controls the throttle opening electronically, and by adjusting this, the acceleration / deceleration of the vehicle is adjusted to match the target acceleration / deceleration. The shift control unit 18 downshifts in response to the downshift request. Further, the VSC ECU 22 controls the brake actuator 20 in response to a brake request to decelerate the vehicle. An alarm device 24 is also connected to the VSC ECU 22. The alarm device 24 is composed of a speaker, and outputs an emergency alarm under the control of the VSC ECU 22. It is also preferable to display on a display or output sound.
[0020]
In this example, vehicle information such as a vehicle speed and a set of an automatic travel (cruise control) mode is supplied to the inter-vehicle control ECU 12 via the engine ECU 14. The inter-vehicle control ECU 12 performs inter-vehicle distance control as described above when set to the cruise control mode, and does not perform inter-vehicle distance control in the normal travel mode that is not set. The cruise control mode is set by turning on the set switch. In the cruise control mode, when an accelerator operation is performed, the accelerator operation is given priority only while the operation is being performed, and the vehicle travels in the normal travel mode. When the accelerator is released, the cruise control mode is restored. On the other hand, when the brake operation is performed in the cruise control mode, the vehicle returns to the normal travel mode and does not shift to the cruise control mode until the next set operation is performed.
[0021]
The engine ECU 14 also performs fuel injection control and the like, and the VSC ECU 22 also performs other controls for stable running of the vehicle, but these are not described here.
[0022]
“First Embodiment”
The first embodiment relates to control when cruise control is set in the inter-vehicle control ECU 12.
[0023]
First, the control of FIG. 2 will be described. When the cruise control is set (S11), it is determined whether the preceding vehicle needs to be decelerated (S12). If “YES” in this determination, it is determined whether a downshift, a brake control, or an approach warning is necessary (S13). If YES in this determination, it is determined whether it is within Tb seconds from the cruise control set (S14). If YES in this determination, a request signal for downshifting (overdrive cut or downshifting to the third speed) or brake control or approach warning is not transmitted (S15). Note that if NO in S12 or S13, a request for deceleration is not generated originally, and in this case, the process also proceeds to S15. In S15, throttle closing control is not prohibited, and deceleration by throttle closing may be performed.
[0024]
On the other hand, if Tb seconds elapse after the cruise control is set and the determination in S14 is NO, a shift down or brake control or approach warning is transmitted to the engine ECU 14 (S16), and the engine ECU 14 performs the corresponding control ( Shift down, brake control or approach warning) is performed (S17). In this example, the inter-vehicle distance control includes (i) throttle closing, (ii) throttle closing + shift down, (iii) throttle closing + shift down + brake control, (iv) throttle closing + shift down + brake control + There are four approach alarms, and request signals are generated in this order according to the distance between vehicles. In this description, for the sake of simplicity, it is described that control is sequentially added. It is also preferable to generate an alarm to notify the driver when the brake control is performed. That is, when the brake control is being performed, it is preferable to continuously output the alarm during that time. Also, as will be described later, this warning during brake control and the approach warning that prompts the driver to operate the brake when the distance between the vehicles cannot be maintained due to the brake control are different in urgency level. It is preferable to do.
[0025]
Furthermore, it is preferable that an alarm be generated at the start of a cruise control mode (automatic running mode) including brake control or when this mode is canceled. This allows the driver to recognize the control state.
[0026]
In this manner, deceleration control and warning control are prohibited immediately after the cruise control is set. When setting a cruise control, the vehicle speed is often increased to the vehicle speed at which the vehicle is desired to be set, and the vehicle is often approaching the preceding vehicle at the time of setting. The driver has created a situation that is close to the preceding car on his own will, and is fully aware of the situation. Therefore, it is not preferable that a sudden deceleration or warning be issued immediately after setting. According to the present embodiment, unnecessary deceleration and generation of an alarm can be prevented. In addition, the preceding vehicle that has been accelerating does not decelerate suddenly, which is preferable for the following vehicle.
[0027]
Next, the control of FIG. 3 will be described. First, when the cruise control is set (S21), the detected inter-vehicle distance D at that time is set to Db (S22). Then, similarly to the case of FIG. 2, it is determined whether deceleration is necessary (S23), whether a downshift or brake control or an approach warning is necessary (S24), and within Tb seconds (S25). If YES in all, it is determined whether the current inter-vehicle distance D is equal to or less than β × Db (S26). Here, β is a predetermined value larger than 0 and smaller than 1 (0 <β <1). If this determination is NO, a request signal for downshift, brake control, or approach warning is not transmitted (S27). As a result, as in the case of FIG. 2, unnecessary deceleration or warning can be prevented. In S23 and S24, also in the case of NO, the process proceeds to S27.
[0028]
On the other hand, if YES in S26, a downshift or brake control or approach warning request signal is transmitted (S28), and the engine ECU 14 generates a downshift or brake control or an approach warning. In S25, in the case of NO, since a predetermined time has elapsed after setting, the process proceeds to S28, and a deceleration and approach warning are performed.
[0029]
As described above, in this embodiment, when the ratio of the inter-vehicle distance D to the inter-vehicle distance Db becomes sufficiently small in S26, deceleration or alarm control is performed. This makes it possible to control deceleration or alarm when the vehicle approaches too much after the set.
[0030]
In S26, a one-step determination is made that the current inter-vehicle distance D is β × Db or less. However, it is also preferable to divide this determination into a plurality of stages. For example, β₀As a value larger than 0 and smaller than β (0 <β₀<Β) is set, and if the inter-vehicle distance D is equal to or less than β × Db, downshift or brake control is performed, and the inter-vehicle distance D is β₀It is also preferable to generate a warning at the following times.
[0031]
“Second Embodiment”
The present embodiment relates to the control of the inter-vehicle distance control ECU 12 when the accelerator is released after the accelerator operation is performed when the cruise control is set.
[0032]
As shown in FIG. 4, it is first determined whether or not the preceding vehicle needs to be decelerated (S31). If “YES” in this determination, it is determined whether a downshift, a brake control, or an approach warning is necessary (S32). If YES in this determination, it is determined whether or not the accelerator has been released (S33). This is determined by a change in the signal for detecting the accelerator opening 0 degree. If this determination is also YES, it is determined whether it is within Tb seconds from the cruise control set (S34). And if it is YES by this determination, the request signal about a shift down or brake control, or an approach warning will not be transmitted (S35). Note that if NO in S31 or S32, a request for deceleration is not originally generated, and thus the process also proceeds to S35.
[0033]
On the other hand, if it is not after the accelerator opening is 0 degree in S33, or if Tb seconds have elapsed after the cruise control is set and the determination in S34 is NO, a shift down or brake control or approach warning is issued. This is transmitted to the engine ECU 14 (S36), and the engine ECU 14 performs the corresponding control (shift down or brake control or approach warning) (S37).
[0034]
Thus, immediately after the accelerator is released, deceleration control and alarm control are prohibited. When the cruise control is set, if you step on the accelerator and approach the preceding vehicle, the approach is done at the driver's will, and you are generally prepared to step on the brakes, and you will have a large deceleration There are many situations that do not expect. Therefore, it is not preferable that a sudden deceleration or warning be issued immediately after the accelerator is released. According to the present embodiment, unnecessary deceleration and generation of an alarm can be prevented. Note that the determination in S33 is YES immediately after the accelerator is released, and is YES for Tb seconds if the accelerator is not stepped on thereafter. This can be easily achieved by providing a flag that is turned off when the accelerator is depressed, turned on when the accelerator is depressed, and turned off when the determination in S34 is YES.
[0035]
Next, the control of FIG. 5 will be described. First, as in the case of FIG. 4, it is determined whether deceleration is required (S41), whether a downshift or brake control or an approach warning is required (S42), and whether the accelerator has been released (S43). If all are YES, the detected inter-vehicle distance D at that time is set to Db (S44). Further, it is determined whether it is within Tb seconds from the cruise control set (S45). If YES, it is determined whether the current inter-vehicle distance D is equal to or less than β × Db (0 <β <1) (S46). If the determination is NO, a downshift, brake control, or approach warning request signal is not transmitted (S47). As a result, as in the case of FIG. 4, unnecessary deceleration or warning can be prevented. In S41 and S42, also in the case of NO, the process proceeds to S47.
[0036]
On the other hand, if YES in S46, a downshift or brake control or approach warning request signal is transmitted (S48), and the engine ECU 14 generates a downshift or brake control or approach warning (S49). If NO in S43 or S45, the process proceeds to S48, and deceleration warning control is performed.
[0037]
As described above, in this embodiment, as in the example of FIG. 3, when the ratio of the inter-vehicle distance D to the inter-vehicle distance Db becomes sufficiently small during travel after the accelerator operation, deceleration or alarm control is performed. Do. As a result, it is possible to perform deceleration, warning, etc. when the vehicle approaches too much after the set.
[0038]
Note that it is also preferable to divide the determination in S46 into a plurality of stages as in the example of FIG.
[0039]
“Third Embodiment”
The present embodiment relates to the control of the inter-vehicle distance control ECU 12 when the accelerator is stepped on during the downshift control when the cruise control is set.
[0040]
As shown in FIG. 6, it is first determined whether or not the shift-down control is being performed when the cruise control is set (S51). If YES in this determination, it is next determined whether the throttle opening (or the accelerator pedal opening) is larger than a predetermined angle θ1 (S52). If YES in this determination, the timer is counted up (S53), and it is determined whether the timer has exceeded a predetermined time T1 (for example, several seconds) (S54).
[0041]
If the determination in S54 is YES, the downshift control is released (S55), but if the determination in S54 is NO, the downshift control is not released. If NO in S51 or S52, the timer is reset (S56), and the process is terminated. Further, in the case of NO in S54, the process is terminated as it is.
[0042]
Note that the threshold value θ1 for the throttle opening in S52 described above is set as a threshold value for determining the user's acceleration intention independent of normal shift control. In addition, a plurality of θ1s are prepared, T1 is changed in accordance with the plurality of θ1s, and the time required to continue the downshift control is adapted to the throttle opening, thereby performing control more suited to the driver's feeling. be able to. In this case, it is preferable to create a map so that T1 can be changed corresponding to θ1.
[0043]
Thus, when the accelerator is depressed during the downshift control, the downshift control is continued for a predetermined time. As a result, it is possible to prevent a shift up immediately after the accelerator is depressed. When a shift up occurs, there is a possibility that a large shock may occur due to a shock caused by this shift and an abrupt change from small to large engine torque due to depression of the accelerator. According to this embodiment, occurrence of such a shock can be prevented.
[0044]
In the above example, the inter-vehicle control ECU 12 continues the downshift request for a predetermined time. However, the shift control unit 18 can employ the above-described logic. That is, the inter-vehicle control ECU 12 outputs a downshift request without considering information on the throttle opening. On the other hand, the shift control unit 18 receives information about the throttle opening, and if the throttle opening is greater than or equal to a predetermined value, the downshift control is continued. Then, the shift down control is canceled after a predetermined time has elapsed. According to such a system, even when the inter-vehicle control ECU 12 holds a downshift request and breaks down, the downshift control can be canceled in accordance with the accelerator operation, and the system becomes fail-safe.
[0045]
“Fourth Embodiment”
In the present embodiment, even if the vehicle speed control content based on the relative relationship with the preceding vehicle is deceleration control, if the inter-vehicle distance is greater than or equal to a predetermined distance, the specific deceleration means is not operated. In particular, the present invention relates to processing in the case where the preceding vehicle exists far away. As shown in FIG. 7, it is first determined whether the preceding vehicle needs to be decelerated (S61). If YES in this determination, it is determined whether the throttle is fully closed, downshifted, or deceleration controlled by braking (S62). If YES in this determination, the detected inter-vehicle distance D is a preset threshold value D.₀It is determined whether it is below (S63). If NO in this determination, a request for deceleration control by throttle fully closed or downshifting or braking is not transmitted to the engine ECU 14 (S64). Note that if NO in S61 or S62, the process also proceeds to S64.
[0046]
On the other hand, in the case of YES in S63, a request for deceleration control by throttle fully closed or downshifting or braking is transmitted to the engine ECU 14 (S65), and the engine ECU 14 performs these controls (S66).
[0047]
As described above, in the present embodiment, when the inter-vehicle control ECU 12 issues a throttle fully closed or downshift request, the inter-vehicle distance is a predetermined value D.₀Limited to the following cases.
[0048]
In the inter-vehicle control ECU 12, the condition for starting the throttle fully closed, downshifting or braking deceleration control is that the target acceleration / deceleration obtained by searching the map based on the relative speed, the own vehicle speed, the inter-vehicle distance, etc. is a predetermined value. It starts when it becomes. This control is automatic control and is set to decelerate early. For example, even at a distance of 60 m or more, if the target deceleration increases, throttle fully closed or downshift control is started. However, the timing when a general driver discovers a preceding vehicle in normal driving and releases his or her foot from the accelerator pedal, or when the brake is released is after the preceding vehicle has approached a little more. For this reason, when the preceding vehicle is far away, if the throttle is fully closed or the vehicle is decelerated by shifting down or braking, the driver feels uncomfortable. Therefore, when the throttle is fully closed or downshifted or the vehicle is decelerated by braking, the inter-vehicle distance is a predetermined distance D.₀By limiting to the following, control suitable for the driver's feeling can be performed. The distance D₀May be set from the timing when the driver removes his / her foot from the accelerator pedal or the time when the driver steps on the brake. Further, this distance may be changed according to traveling conditions such as the own vehicle speed. In addition, a filter based on the inter-vehicle distance can be incorporated into the start conditions of deceleration control by throttle fully closed, downshifting, or braking, but the map based on the above-mentioned inter-vehicle distance, relative speed, etc. is left as it is. It is effective to add such a judgment.
[0049]
Here, whether the preceding vehicle is in the own lane is determined by estimating the radius of curvature R of the currently running curve from a steering sensor or the like. However, in this system, in principle, it is easy to lose sight of the preceding vehicle at the entrance / exit of the curve, or misidentify the vehicle in the adjacent lane. Such loss or misdetection is likely to occur when the inter-vehicle distance is far away, such as 60 to 80 m or more. By prohibiting deceleration control based on the inter-vehicle distance as in the present embodiment, unnecessary deceleration due to erroneous detection of the preceding vehicle can be prevented.
[0050]
“Fifth Embodiment”
In the present embodiment, when the road on which the vehicle is traveling is not a flat road, the vehicle speed control by the vehicle speed control means is changed. Here, a case where the control is changed depending on whether or not the vehicle is traveling on a downhill road will be described. As shown in FIG. 8, it is first determined whether or not the road on which the vehicle is traveling is a downhill road (S71). In this determination, (i) it was determined that the throttle was fully closed and the integrated value of the increase in the vehicle speed was more than a certain value, (ii) that the acceleration of the vehicle was positive for a certain time or more, (iii) Gradient data is stored as map data, and gradient data at the current location is read and determined. (Iv) Gradient data is received from the road side by road-to-vehicle communication or the like. (V) A gradient detection sensor is mounted on the vehicle, and determination is based on the detected value. , Etc. can be used.
[0051]
If YES in this determination, the target inter-vehicle time (or inter-vehicle distance) is set to the currently set inter-vehicle time (or inter-vehicle distance) + α1 (S72). That is, when it is determined that the road is downhill, the target inter-vehicle time (or inter-vehicle distance) is greatly changed by a predetermined amount (α).
[0052]
Further, the shift down start timing is advanced (S73). For example, when a shift down request start in S74, which will be described later, is issued when the absolute value of (current deceleration)-(target deceleration) is greater than a predetermined threshold, the threshold is changed to a smaller value. . It is also possible to always perform a downshift at the timing when the accelerator is fully closed.
[0053]
Next, it is determined whether a downshift is necessary (S74). As described above, this determination can be made based on the difference between the target deceleration and the current deceleration. If the determination is YES, a downshift request is transmitted to the engine ECU 14 (S75).
[0054]
Thus, in the present embodiment, on the downhill road, the target inter-vehicle distance can be set far and the downshift can be performed earlier. Thus, it is possible to obtain a sufficient deceleration and effectively prevent the vehicle from approaching the preceding vehicle too much.
[0055]
Further, if a downhill road is determined in S71, a negative value is set as α1 in S72, and the downshift timing is set to be delayed in S73, the present invention can also be applied to an uphill road. Further, the determination of whether or not a downshift is necessary in S74 can be made based on the difference between the target vehicle speed and the current vehicle speed.
[0056]
In other words, on the uphill road, downhill road, and flat road, the optimum inter-vehicle distance can be maintained in each case by changing the deceleration start timing and the target inter-vehicle distance.
[0057]
“Sixth Embodiment”
In the present embodiment, an alarm 1 is issued while the vehicle traveling control means is decelerating by the brake control. Further, when the driver needs to step on the brake, an approach alarm different from the alarm 1 is issued. appear. As shown in FIG. 9, it is first determined whether or not an alarm 2 (approach alarm) needs to be generated from the inter-vehicle distance, relative speed, and the like with the preceding vehicle (S81). This determination is a determination as to whether or not the brake operation by the inter-vehicle distance control is sufficient, and the brake operation by the driver is necessary. If the determination is YES, an alarm 2 is generated (S82). This alarm 2 (approach alarm) is an alarm for requesting an emergency brake operation from the driver, and an alarm with a high degree of urgency such as a strong tone alarm or a voice requesting a brake operation is suitable.
[0058]
If NO in the determination in S81, it is determined whether or not the approach warning 1 needs to be generated from the inter-vehicle distance and relative speed with the preceding vehicle (S83). This is a determination as to whether or not the deceleration control by the brake is performed by the inter-vehicle distance control, and is a determination under a milder condition than the determination of the alarm 2 (approach alarm). If this determination is NO, processing for the alarm is unnecessary and the process returns to S81. If YES in S83, it is determined whether brake control is started (S84). This is performed by confirming whether a brake request is transmitted from the inter-vehicle control ECU 12 to the engine ECU 14. This determination is repeated while this confirmation is not taken. And when transmission of a brake request | requirement is confirmed, the warning 1 is output from the warning device 24 (S85). This alarm 1 is an alarm for notifying the driver that the brake control is being performed, and is set to a relatively gentle tone. Then, if an alarm is generated in S82 or S85, the process is terminated.
[0059]
In normal control, when the inter-vehicle distance from the preceding vehicle is reduced, the alarm 1 is continuously generated during the brake control. Further, when the inter-vehicle distance is narrowed, deceleration is insufficient only by brake control, and a brake operation by the driver is necessary, an alarm 2 (approach alarm) is generated. However, if the driver approaches the vehicle ahead and releases the accelerator, the deceleration control will not be in time, and if the driver's brake operation is required immediately, 2 (approach warning) will be generated immediately. It will be.
[0060]
As described above, according to the present embodiment, when the brake is operated, the alarm 1 for informing this is issued. In the brake control based on the inter-vehicle distance control, the braking G (deceleration) is limited to a very small value. Therefore, if a large deceleration is required, this is assumed to be compensated by the driver. Alarm 1 can alert the driver that a brake operation may be required and the driver can be prepared for that operation. Further, since the generation of the alarm 1 is limited to the time when the brake control is actually performed, the alarm is not alarmed to the driver. That is, if the alarm is output before the brake is not operated and then the brake is operated, the driver feels uncomfortable. Note that it is also preferable that the alarm 1 does not occur for a certain time after the brake control is performed. Thereby, it is possible to prevent an alarm from occurring when the distance between the vehicles is easily recovered by the brake control.
[0061]
In an emergency where the deceleration is insufficient in the brake operation by the inter-vehicle control, an alarm 2 having a different tone is output. As a result, the driver can be surely notified that the brake operation or the avoidance operation is necessary.
[0062]
【The invention's effect】
As described above, according to the present invention, immediately after the mode is switched between the normal travel mode and the automatic travel mode, the operating condition of the vehicle speed control device in the new mode is changed. For this reason, improper control at the time of mode transition can be prevented, and driving without a sense of incongruity for the driver can be performed. Also, the timing of alarm generation can be made appropriate.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the overall configuration of a travel control device of the present invention.
FIG. 2 is a flowchart showing an operation example of the first embodiment.
FIG. 3 is a flowchart showing another operation example of the first embodiment.
FIG. 4 is a flowchart showing an operation example of the second embodiment.
FIG. 5 is a flowchart showing another operation example of the second embodiment.
FIG. 6 is a flowchart showing an operation example of the third embodiment.
FIG. 7 is a flowchart showing an operation example of the fourth embodiment.
FIG. 8 is a flowchart showing an operation example of the fifth embodiment.
FIG. 9 is a flowchart showing an operation example of the sixth embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Laser radar apparatus, 12 Distance control ECU, 14 Engine ECU, 16 Electronic throttle, 18 Shift control part, 20 Brake actuator, 22 VSC ECU, 24 Alarm apparatus

Claims (1)

In a vehicle travel control device having detection means for detecting an inter-vehicle distance with a preceding vehicle, and a control means for controlling the speed of the host vehicle based on the detected inter-vehicle distance ,
Normal driving mode that controls acceleration / deceleration based on driver's operation,
An automatic travel mode for controlling the vehicle speed by the control means;
Have
Immediately after switching from the normal travel mode to the automatic travel mode by the device, even if the vehicle speed control content based on the inter-vehicle distance from the preceding vehicle is deceleration control, at least the brake is not operated for a predetermined time, but the predetermined time Even when the distance between the vehicle and the preceding vehicle approaches the vehicle distance Db from the preceding vehicle immediately after switching to the automatic driving mode, the vehicle distance Db is more than β × Db multiplied by a coefficient β (0 <β <1). In the vehicle driving control device , the brake is operated .

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