JP2008168722A - Travel controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a travel controller that reduces the possibility of imparting an unpleasant feeling or an incongruity sense to a driver when changing over a travel mode. <P>SOLUTION: Setting of the travel mode is changed over from a following mode to an acceleration mode by following mode changeover decision processing (S514, S525) (1) when a preceding vehicle acceleration αf is 0 or above and when relative velocity Vr with the preceding vehicle is a preset lower limit value or above (S521-S524), or (2) when the preceding vehicle acceleration αf is the preset lower limit value or above and when a collision time Tc (=-D/Vr) obtained by performing positive/negative sign inversion of a ratio of a relative distance D and the relative velocity Vr with the preceding vehicle satisfies that the collision time Tc is a negative value or is the preset lower limit value or above (S511-S513). Accordingly, it is prevented that the travel mode is changed over to the acceleration mode when the preceding vehicle decelerates, and following can be responsively performed when the preceding vehicle starts acceleration. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a travel control device that allows a host vehicle to follow and travel while maintaining an appropriate inter-vehicle distance from a preceding vehicle.

  2. Description of the Related Art Conventionally, there is known an auto-cruise control device capable of so-called inter-vehicle cruise that travels following a preceding vehicle so that the inter-vehicle distance with the preceding vehicle matches the target inter-vehicle distance regardless of the driver's operation. Also, in this type of device, when traveling by inter-vehicle cruise, speed adjustment is performed in order to keep the inter-vehicle distance appropriately with the preceding vehicle, and acceleration / deceleration control is performed in acceleration mode, constant speed mode, deceleration mode, etc. There are known methods for switching to a plurality of driving modes. In such acceleration / deceleration control, the timing at which the driving mode is switched is an important factor in determining the ride comfort of the driver.

As one of the driving controls for switching the driving mode, the driving mode is set to the constant speed mode when the error between the target inter-vehicle distance and the actual inter-vehicle distance (hereinafter referred to as “inter-vehicle distance error”) or the relative speed is large. There is known one that switches from the acceleration mode to the acceleration mode, and switches the traveling mode from the constant speed mode to the deceleration mode when the inter-vehicle distance error and the relative speed are small (see, for example, Patent Document 1).
JP 11-348599 A

  However, in the traveling control described in Patent Document 1, when the preceding vehicle is decelerated, switching to the acceleration mode occurs, or when the preceding vehicle changes from deceleration to acceleration, the acceleration mode is entered. There was a problem that the timing of switching was delayed.

  Specifically, for example, even if the vehicle is interrupting while decelerating, if it satisfies the conditions of the inter-vehicle distance error and the relative speed, it switches to the acceleration mode. There was a possibility of giving anxiety. Also, if the preceding vehicle starts accelerating while the host vehicle running in the constant speed mode is approaching the preceding vehicle, even if the inter-vehicle distance is sufficient, the vehicle enters the acceleration mode until the relative speed condition is satisfied. Since switching is not performed, in such a case, there is a possibility that the driver may feel uncomfortable based on poor control responsiveness.

That is, in the conventional method, the vehicle may be placed in a traveling mode that does not match the traveling state of the preceding vehicle, which causes a problem that the driver feels uneasy or uncomfortable.
In order to solve the above-described problems, an object of the present invention is to provide a travel control device that reduces the possibility that the driver will feel uneasy or uncomfortable when the travel mode is switched.

  The travel control apparatus according to claim 1 of the present invention, which has been made to achieve the above object, includes driving force adjusting means for adjusting the driving force transmitted from the engine to the wheels without depending on the operation of the driver. The vehicle speed detection means detects the vehicle speed of the host vehicle, and the preceding vehicle information detection means detects the relative distance and relative speed of the preceding vehicle with respect to the own vehicle.

  Then, the acceleration calculating means calculates the acceleration of the preceding vehicle based on the own vehicle speed detected by the vehicle speed detecting means and the relative speed detected by the preceding vehicle information detecting means. However, here, if the relative speed is positive, the preceding vehicle moves away from the own vehicle, and if the relative speed is negative, the preceding vehicle approaches the own vehicle.

  At the same time, the first target acceleration setting means sets the first target acceleration for matching the inter-vehicle distance with the preceding vehicle to the preset target inter-vehicle distance based on the relative distance and the relative speed, and the second target acceleration. The acceleration setting means sets a second target acceleration obtained by adding an additional acceleration set according to the preceding vehicle acceleration to the first target acceleration.

  The inter-vehicle distance control means has a plurality of travel modes including at least a follow-up mode for controlling the driving force adjusting means using the first target acceleration and an acceleration mode for controlling the driving force adjusting means using the second target acceleration. The travel mode switching means switches the travel mode based on the detection results of the preceding vehicle information detection means and the acceleration calculation means.

  In particular, in the present invention, the first switching condition is that the traveling mode switching means determines that the preceding vehicle acceleration is non-negative based on the preceding vehicle acceleration and the relative speed, and that the relative speed is equal to or higher than a preset set speed. When the first switching condition is satisfied, the tracking mode is switched to the acceleration mode.

  Therefore, according to the traveling control apparatus of the present invention, even if the relative speed is equal to or higher than the set speed, if the preceding vehicle acceleration is negative, the preceding vehicle is decelerated because the following mode is not switched to the acceleration mode. However, it is possible to prevent the switching to the acceleration mode from occurring.

  For example, when the vehicle that interrupts while decelerating becomes the preceding vehicle, even if the relative speed with the preceding vehicle is higher than the set speed, it will follow this and switch to the acceleration mode Can be prevented. As a result, it is possible to prevent the vehicle from being placed in a traveling mode that does not match the traveling state of the preceding vehicle, and to prevent the driver from feeling uneasy or uncomfortable.

Note that the setting speed of the first switching condition may be about 2 [km / h] as described in claim 2, for example.
According to a third aspect of the present invention, the traveling mode switching means performs the second switching that the state in which the preceding vehicle acceleration is non-negative and the relative speed is equal to or higher than the set speed continues for a preset time. As a condition, when the second switching condition is satisfied, switching from the follow-up mode to the acceleration mode may be performed.

  In this case, even if the preceding vehicle acceleration is non-negative and the relative speed is greater than or equal to the set speed, as long as the state does not continue for longer than the set time, the tracking mode will not switch to the acceleration mode. It is possible to prevent mode switching from being repeated frequently when traveling at a relative speed close to.

  Further, according to a fourth aspect of the present invention, the traveling mode switching means is configured such that the preceding vehicle acceleration exceeds a preset lower limit acceleration, and the collision time is negative or negative when the ratio between the relative distance and the relative speed is inverted. As a third switching condition that the time is equal to or longer than a preset lower limit time, the tracking mode may be switched to the acceleration mode even when the third switching condition is satisfied.

  In this case, when the preceding vehicle acceleration exceeds the lower limit speed, if the relative speed is positive (that is, the collision time is negative), the relative distance from the preceding vehicle is not limited even if the relative speed is negative. If it is sufficiently large (that is, if the collision time is equal to or longer than the lower limit time), the tracking mode is immediately switched to the acceleration mode.

  Therefore, according to the travel control device of the present invention, for example, when the host vehicle traveling in the follow-up mode is approaching a preceding vehicle that is sufficiently separated in relative distance (that is, the relative speed is negative). When the preceding vehicle starts accelerating, switching to the acceleration mode is performed with good responsiveness regardless of the relative speed, so that it is possible to prevent the driver from feeling uncomfortable with respect to the mode switching timing.

  Note that the travel control device according to the present invention shifts from the follow-up mode to the acceleration mode when, for example, the first switching condition and the second switching condition are omitted and the third switching condition is satisfied. You may comprise so that switching may be performed.

Further, the lower limit acceleration of the third switching condition may be about 0.045 G [m / s ² ], for example, as described in claim 6.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a traveling control apparatus to which the present invention is applied.
<Configuration of travel control device>
As shown in FIG. 1, the travel control device includes an inter-vehicle distance control electronic control device (hereinafter referred to as “inter-vehicle control ECU”) 2 which is a main part of the present invention.

  The inter-vehicle distance control ECU 2 is an electronic circuit mainly composed of a microcomputer, and includes an engine electronic control device (hereinafter referred to as “engine ECU”) 3, a brake electronic control device (hereinafter referred to as “brake ECU”) 4, and meter electronics. Data communication is performed with a control device (hereinafter referred to as “meter ECU”) 5 through a LAN communication bus. Note that data communication between ECUs uses a CAN ("Controller Area Network" proposed by Robert Bosch, Germany) protocol that is generally used in in-vehicle networks. The inter-vehicle control ECU 2 is connected with a front recognition sensor 1, an alarm buzzer 2a, and a switch 2b.

  The forward recognition sensor 1 is configured as a so-called “radar sensor”, detects a target such as a preceding vehicle or a roadside object by transmitting and receiving radar waves, and includes preceding vehicle information including information on these targets. Or, the diagnostic information of the front recognition sensor 1 itself is transmitted to the inter-vehicle distance control ECU 2. The preceding vehicle information includes at least a relative speed Vr and a relative distance D with respect to the detected target.

  The engine ECU 3 receives information on the current vehicle speed of the vehicle detected by the vehicle speed sensor 3a, and together with detection information (engine control state, accelerator operation state) from a throttle opening sensor and an accelerator pedal opening sensor (not shown), the current vehicle speed of the vehicle. Is transmitted to the inter-vehicle distance control ECU 2. Further, the engine ECU 3 receives a target acceleration, a fuel cut request (during engine braking), diagnosis information, and the like from the inter-vehicle control ECU 2, and an internal combustion engine (in this case, a gasoline engine) according to the driving state specified from the received information. The driving force of the internal combustion engine is controlled by outputting a driving command to a throttle actuator (not shown) for adjusting the throttle opening of the engine.

  The brake ECU 4 determines the brake pedal state determined based on the information from the M / C pressure sensor (not shown) in addition to the detection information (steering angle and yaw rate) from the steering sensor 4a and the yaw rate sensor 4b. Send. The brake ECU 4 receives the target acceleration, the brake request, etc. from the inter-vehicle control ECU 2, and opens and closes the pressure increase control valve / pressure reduction control valve provided in the brake hydraulic circuit according to the received information and the determined brake pedal state. The brake force is controlled by driving a brake actuator (not shown).

  The meter ECU 5 is for displaying display data (current vehicle speed, engine speed, door open / close state, transmission shift range, etc.) representing various vehicle states on a meter display (not shown).

  The inter-vehicle control ECU 2 receives information such as the current vehicle speed and the idle control state from the engine ECU 3, and receives information such as the steering angle, yaw rate, brake control state, and brake pedal state from the brake ECU 4. Further, the inter-vehicle control ECU 2 periodically receives preceding vehicle information (such as relative distance D and relative speed Vr) from the front recognition sensor 1, and information such as the current vehicle speed, estimated R (the curve radius of the curve on which the host vehicle travels), and the like. Information is transmitted to the forward recognition sensor 1. Then, the inter-vehicle control ECU 2 uses the engine ECU 3 as a control command value for appropriately adjusting the inter-vehicle distance from the preceding vehicle based on the detection signal (cruise control ON / OFF, target inter-vehicle time changing operation, etc.) from the switch 2b. , Various information (target acceleration, fuel cut request, brake request, diagnosis, display data, etc.) is transmitted to the brake ECU 4 and the meter ECU 5. Further, the inter-vehicle control ECU 2 determines whether or not an alarm is generated, and sounds an alarm buzzer 2a when an alarm is required.

  Although not shown, the switch 2b performs a cruise set switch for starting an auto cruise control (hereinafter referred to as "vehicle cruise") for performing acceleration / deceleration control in order to appropriately maintain a distance between the preceding vehicle and the vehicle. A target inter-vehicle setting switch for the driver to select a target inter-vehicle time Tm that is set as a target value of the inter-vehicle time Ta (for example, in three stages of large, medium, and small), for ending the inter-vehicle cruise It consists of a cancel switch. Note that the time required for the vehicle to travel the current relative distance D from the preceding vehicle at the current host vehicle speed Vn is the inter-vehicle time Ta (= D / Vn).

<Outline of inter-vehicle distance control>
Next, the inter-vehicle distance control process executed by the inter-vehicle control ECU 2 will be described in detail along the flowchart shown in FIG. The inter-vehicle distance control process is repeated every predetermined period T (hereinafter referred to as unit [s]) until the operation of the cancel switch is detected after the operation of the cruise set switch is detected. It is activated.

  When the inter-vehicle distance control process is activated, first, in S110, the current vehicle speed of the vehicle detected by the vehicle speed sensor 3a is extracted from the information received by the inter-vehicle control ECU 2 from the engine ECU 3, as the own vehicle speed Vn. The relative distance D and the relative speed Vr are extracted from the preceding vehicle information received from the recognition sensor 1.

  In subsequent S130, the preceding vehicle acceleration αf is calculated based on the host vehicle speed Vn extracted in the previous S110 and the relative speed Vr extracted in S120. Specifically, the preceding vehicle acceleration αf is obtained by differentiating the own vehicle speed Vn (the value obtained by subtracting the own vehicle speed Vn extracted in the previous period from the own vehicle speed Vn extracted in the current period is divided by the period T). And the relative acceleration αr calculated by differentiating the relative speed Vr (similar to the case of the own vehicle speed Vn) and the relative acceleration αr.

αf = αn + αr (1)
In subsequent S140, a travel mode determination process is performed for determining which travel mode to execute control from among a plurality of travel modes (described later) provided for inter-vehicle cruise.

In subsequent S150, target acceleration calculation processing for calculating a target acceleration that is a target value of acceleration for performing acceleration / deceleration control according to the travel mode determined in S140 is executed.
Finally, in S160, the target acceleration calculated in the previous S150 is transmitted to the engine ECU 3 and the brake ECU 4, and the inter-vehicle distance control process is terminated.

<Details of travel mode determination processing>
Next, the travel mode determination process executed in S140 will be described with reference to the flowchart shown in FIG. In addition, specifically, three modes including an acceleration mode, a deceleration mode, and a follow-up mode are prepared as the travel mode, and it is assumed that the travel mode is initially set to the follow-up mode at the start of the inter-vehicle cruise.

First, in S210, it is determined whether the current travel mode is an acceleration mode, a deceleration mode, or a follow-up mode.
If the current travel mode setting is the acceleration mode, the process proceeds to S220, and an acceleration mode switching determination process is performed to determine whether or not the travel mode setting is switched from the acceleration mode to the follow-up mode. Similarly, if it is the deceleration mode, the process proceeds to S230, and a deceleration mode switching determination process for determining whether or not to switch the travel mode setting from the deceleration mode to the tracking mode is executed. The process proceeds to S240, and a follow-up mode switching determination process is performed for determining whether or not the travel mode setting is switched from the follow-up mode to the acceleration mode or the deceleration mode.

  In other words, the driving mode is switched from the following mode to the acceleration mode, from the acceleration mode to the following mode, from the following mode to the deceleration mode, and from the deceleration mode to the following mode, but from the acceleration mode to the deceleration mode and from the deceleration mode to the acceleration mode. Switching is set not to be performed. Therefore, for example, when shifting from the acceleration mode to the deceleration mode and when shifting from the deceleration mode to the acceleration mode, the tracking mode is always switched once.

<Details of acceleration mode switching determination processing>
Next, the acceleration mode switching determination process executed in S220 will be described in detail with reference to the flowchart shown in FIG. In the acceleration mode switching determination process, the deceleration mode switching determination process, and the follow-up mode switching determination process, a counter (hereinafter referred to as “continuation state counter”) in which the count value C is updated by these processes is used, and the inter-vehicle cruise is started. Sometimes the count value is initially set to 1.

First, in S310, it is determined whether or not the preceding vehicle acceleration αf (hereinafter unit [m / s ² ]) calculated in S130 is −0.05 or less. Here, when it is determined that the preceding vehicle acceleration αf is not −0.05 or less, the process proceeds to S315.

  In S315, it is determined whether or not the preceding vehicle acceleration αf is 0 or less (that is, the preceding vehicle is not accelerated). Here, if it is affirmed that the preceding vehicle acceleration αf is 0 or less (that is, the preceding vehicle is traveling at a reduced speed or traveling at a constant speed), the process proceeds to S320.

  In S320, the relative speed Vr (hereinafter referred to as unit [km / h]) extracted in S120 is less than 1 (that is, the preceding vehicle is at the same speed or approaching the own vehicle, or It is determined whether or not the relative speed Vr = 1 is moving away at a speed smaller than 1. Here, when it is determined that the relative speed Vr is less than 1, the process proceeds to S330, and the count value C of the continuation state counter is incremented (C ← C + 1).

In subsequent S340, it is determined whether or not the count value C is 4 or more (that is, Vr <1 [km / h] is established for three consecutive periods).
If it is affirmed that the count value C is 4 or more, or if it is affirmatively determined that the preceding vehicle acceleration αf is −0.05 or less in the previous S310, the process proceeds to S350 and the travel mode is changed. Switch the setting from acceleration mode to follow-up mode.

  Subsequent to this, or when it is determined in the previous S315 that the preceding vehicle acceleration αf is not 0 or less, or when it is determined in the previous S320 that the relative speed Vr is not less than 1, the process proceeds to S360.

In S360, the count value C of the continuation state counter is reset to 1.
Subsequent to this, or when it is determined in S340 that the count value C is not 4 or more, the process proceeds to S370.

  In S370, in a follow-up mode switching determination process described later, a calculated value B (k) of a deceleration determination counter (hereinafter referred to as “Bk counter”) used for determination of switching from the follow-up mode to the deceleration mode is calculated according to equation (2). It updates and this acceleration mode switching determination process is complete | finished.

B (k) = B (k−1) + (Vr + 2.5) ² × Sign (Vr + 2.5) (2)
In Expression (3), Sign (A) is a function that is +1 if A is positive, and -1 if A is negative, and therefore, the relative speed Vr is larger than −2.5, which is a threshold value. When the relative speed Vr is smaller than the threshold value −2.5, the value is −1. B (k-1) is the calculated value of the Bk counter obtained in the previous cycle, and the upper limit value of the calculated value B (k) is 0. Further, it is assumed that the calculation value B (k) is initialized to 0 when the inter-vehicle cruise is activated.

  This Bk counter is for continuously monitoring the relationship of the relative speed Vr between the host vehicle and the preceding vehicle not only in the follow-up mode but also in other modes (acceleration mode, deceleration mode), When the relative speed Vr <TH (= −2.5), that is, when the vehicle approaches the preceding vehicle at a relative speed larger than the absolute value | TH | of the threshold, the calculated value B (k) is a negative value. Will be increased.

  As described above, this acceleration mode switching determination process is performed either when the preceding vehicle acceleration αf is −0.05 G or less, or when the preceding vehicle acceleration αf is 0 or less and the relative speed Vr is less than 1 for three consecutive periods. When this condition is satisfied, the travel mode setting is switched from the acceleration mode to the follow-up mode (see FIGS. 8 and 9), and while the acceleration mode continues, the calculated value B (k) of the Bk counter is changed. The update is repeated.

  FIG. 8 is an explanatory diagram showing driving mode switching conditions with a focus on the preceding vehicle acceleration αf and relative speed Vr, and FIG. 9 shows a traveling with a focus on the preceding vehicle acceleration αf and a collision time Tc described later. It is explanatory drawing which showed the mode switching conditions.

<Details of deceleration mode switching judgment processing>
Next, the deceleration mode switching determination process executed in S230 will be described in detail along the flowchart shown in FIG.

First, in S410, the preceding vehicle acceleration αf is −0.05 G or more (that is, the preceding vehicle is traveling at an acceleration or constant speed, or an acceleration smaller than the absolute value | αf | = 0.05 G of the preceding vehicle acceleration). It is determined whether or not the vehicle is decelerating (including | αf | = 0.05G). However, G is a gravitational acceleration (hereinafter, unit [m / s ² ]), and G = 9.8. Here, when it is affirmed that the preceding vehicle acceleration αf is −0.05 G or more, the process proceeds to S420.

  In this S420, the relative speed Vr exceeds −1 (that is, the state where the preceding vehicle is moving at the same speed or away from the own vehicle, or the state where the relative speed is approaching at a speed smaller than the absolute value | Vr | = 1). ) Or not. Here, when it is determined that the relative speed Vr exceeds −1, the process proceeds to S430, and the count value C of the continuation state counter is incremented (C ← C + 1).

  In subsequent S440, it is determined whether or not the count value C is 4 or more (that is, Vr> −1 is established for three consecutive periods). Here, when it is affirmed that the count value C is 4 or more, the process proceeds to S450, and the setting of the travel mode is switched from the deceleration mode to the follow-up mode. In the subsequent S460, the calculated value B (k ).

  Following this, or when it is negatively determined in S420 that the relative speed Vr does not exceed -1 (that is, Vr is equal to or less than -1), or in the previous S410, the preceding vehicle acceleration αf is -0.05G. If not (ie, αf is less than 0.05G), the process proceeds to S470.

In S470, the count value C of the continuation state counter is reset to 1, and the deceleration mode switching determination process is terminated as it is.
Also, if it is determined in S440 that the count value C is not 4 or more (that is, the count value C is less than 4), the deceleration mode switching determination process is terminated.

  In other words, this deceleration mode switching determination process is executed when the preceding vehicle acceleration αf is −0.05 G or more, or when both conditions of the relative speed Vr exceeding −1 for three consecutive periods are satisfied. The setting is switched from the deceleration mode to the follow-up mode (see FIG. 8).

<Follow-up mode switching determination process>
Next, the follow-up mode switching determination process executed in S240 is divided into a process for determining the switch from the follow-up mode to the acceleration mode and a process for determining the switch from the follow-up mode to the deceleration mode. This will be described in detail along the flowchart shown in FIG.

<< Switching from follow-up mode to acceleration mode >>
First, in S511, it is determined whether or not the preceding vehicle acceleration αf calculated in the previous S130 is 0.045G or more. Here, if the preceding vehicle acceleration αf is 0.045G or more, the process proceeds to S512. In addition, although the setting of the lower limit value of the preceding vehicle acceleration αf is 0.045G, it can be changed based on a range obtained in advance through experiments or the like.

  In S512, a collision time Tc (= −D / Vr: unit [s]) obtained by reversing the sign of the relative distance D and the relative speed Vr is obtained, and the collision time Tc is negative (that is, the relative speed). It is determined whether or not Vr is positive. If it is determined that the collision time Tc is not negative, the process proceeds to S513.

In S513, it is determined whether or not the collision time Tc is 30 or more.
Here, when it is affirmed that the collision time Tc is 30 or more, or when it is affirmed that the collision time Tc is negative in the previous S512, the process proceeds to S514 to follow the setting of the travel mode. Switch from mode to acceleration mode.

Following this, or when it is determined in S513 that the collision time Tc is not 30 or more, the process proceeds to S515, and the count value C of the continuation state counter is reset to 1.
The series of determination processes executed in S511 to S515 is set as a third switching condition.

On the other hand, if it is determined in the previous S511 that the preceding vehicle acceleration αf is not 0.045G or more (that is, αf is less than 0.045G), the process proceeds to S521.
In this step S521, the preceding vehicle acceleration αf is 0 or more (specifically, the preceding vehicle is accelerating with an acceleration of the preceding vehicle acceleration αf = 0.045G or less, or is traveling at a constant speed). Whether or not). Here, when it is affirmed that the preceding vehicle acceleration αf is 0 or more, the process proceeds to S522.

  In S522, it is determined whether or not the relative speed Vr is 2 or more (that is, the preceding vehicle is moving away from the host vehicle at a speed higher than the relative speed Vr = 2 (including Vr = 2)). . Here, when it is determined that the relative speed Vr is 2 or more, the process proceeds to S523, and the count value C of the continuation state counter is incremented (C ← C + 1).

  In subsequent S524, it is determined whether or not the count value C is 4 or more (that is, Vr ≧ 2 is established for three consecutive periods). Here, when it is affirmed that the count value C is 4 or more, the process proceeds to S525, and the travel mode setting is switched from the follow-up mode to the acceleration mode.

Following this, or if it is determined in the previous S522 that the relative speed Vr is not 2 or more (that is, Vr is less than 2), the process proceeds to S540.
In S540, the count value C of the continuation state counter is reset to 1.

Subsequent to this, or when it is determined in the previous S524 that the count value C is not 4 or more, or following the previous S515, the process proceeds to S550.
In S550, the calculated value B (k) of the Bk counter is updated, and the follow-up mode switching determination process ends.

  A series of determination processes executed in S521 to S525 and S540 so far are set as the second switching condition. In addition, among the second switching conditions, a series of determination processes (that is, processes that do not use the continuation state counter) that are executed while omitting S523 and S524 are set as the first switching conditions.

  That is, this follow-up mode switching determination process is a case where the preceding vehicle acceleration αf is 0.045 G or more, and the condition that the collision time Tc is negative or the collision time Tc is 30 or more. When it is satisfied, the travel mode setting is switched from the follow mode to the acceleration mode (see FIG. 9). Furthermore, even when the preceding vehicle acceleration αf is smaller than 0.045G, if the preceding vehicle acceleration αf is 0 or more and Vr is 2 or more for three consecutive cycles, the travel mode is set from the follow mode. Switch to the acceleration mode (see FIG. 8). The calculated value B (k) of the Bk counter is repeatedly updated regardless of whether the travel mode is set to the follow mode or the acceleration mode.

<< Switching from follow-up mode to deceleration mode >>
On the other hand, if it is determined in the previous S521 that the preceding vehicle acceleration αf is not 0 or more (that is, the preceding vehicle is decelerating), the process proceeds to S531.

  In S531, it is determined whether or not the preceding vehicle acceleration αf is less than −0.05G (that is, the preceding vehicle is decelerating at an acceleration greater than the absolute value | αf | = 0.05G of the preceding vehicle acceleration). To do. If it is determined that the preceding vehicle acceleration αf is not less than −0.05G (that is, αf is −0.05G or more), the process proceeds to S532.

  In S532, whether or not the relative speed Vr is −10 or less (that is, the preceding vehicle is approaching the host vehicle at an absolute value | Vr | = 10 or a larger value of the relative speed). Judging. Here, when it is determined that the relative speed Vr is not −10 or less, the process proceeds to S533. In addition, although the setting of the upper limit value of the relative speed Vr is set to −10, for example, it can be changed based on a range obtained in advance by experiments or the like, such as between −2.5 and −10.

In S533, it is determined whether or not the calculated value B (k) of the Bk counter is −10 or less.
Here, when it is affirmed that the calculated value B (k) is −10 or less, or when the relative speed Vr is affirmatively determined to be −10 or less in the previous S532, or in the preceding S531, the preceding vehicle When an affirmative determination is made that the acceleration αf is less than −0.05 G, the process proceeds to S534, and the travel mode setting is switched from the follow mode to the acceleration mode.

  In the subsequent S535, the count value C of the continuation state counter is reset to 1, and in the subsequent S536, the calculated value B (k) of the Bk counter is cleared to 0, and this follow-up mode switching determination process ends.

  On the other hand, if it is determined in S533 that the calculated value B (k) is not -10 or less (that is, the calculated value B (k) exceeds -10), the process proceeds to S540 and the continuation state counter The count value C is reset to 1, the calculated value B (k) is updated in the subsequent S550, and the follow-up mode switching determination process ends.

  That is, in this follow-up mode switching determination process, the preceding vehicle acceleration αf is less than −0.05 G, the relative speed Vr is −10 or less, or the Bk counter calculation value B (k) is −10 or less. When any of the above conditions is satisfied, the travel mode setting is switched from the follow-up mode to the deceleration mode (see FIG. 8). The calculated value B (k) of the Bk counter is cleared to 0 when the travel mode setting is switched from the follow mode to the deceleration mode.

<Target acceleration calculation processing>
Next, the target acceleration calculation process executed in S150 will be described in detail with reference to the flowchart shown in FIG.

  First, in S610, the target inter-vehicle distance Dm is calculated from the equation (3) obtained by multiplying the own vehicle speed Vn extracted in S110 by the target inter-vehicle time Tm preset by the driver in the switch 2b.

Dm = Vn × Tm (3)
In subsequent S620, a first target acceleration αo, which is one of the target accelerations that are acceleration target values for acceleration / deceleration control according to the travel mode determined in S140, is calculated. The first target acceleration αo is obtained by subtracting the target inter-vehicle distance Dm calculated in the previous S610 from the relative distance D detected in the previous S120, and the relative speed Vr detected in S120. Based on the two-dimensional map set in advance. This two-dimensional map is based on results obtained by experiments and the like regarding the relationship between the target acceleration, the inter-vehicle distance error ΔDo, and the relative speed Vr.

  A difference value ΔDo obtained by subtracting the target inter-vehicle distance Dm calculated in the previous S610 from the relative distance D detected in the previous S120, and a relative speed Vr also detected in the S120 are set as preset difference values. It is obtained in light of a two-dimensional map of ΔDo and relative velocity Vr.

  In subsequent S630, it is determined whether or not the setting of the travel mode determined in the previous S140 is the follow-up mode. If an affirmative determination is made in the follow-up mode, the process proceeds to S640.

In S640, the target acceleration is set to the first target acceleration αo calculated in the previous S620, and the target acceleration calculation process is terminated.
On the other hand, if it is determined in S630 that the travel mode is not set to the follow mode (that is, the acceleration mode or the deceleration mode), the process proceeds to S650 and the second target acceleration αt, which is another target acceleration. Is calculated. Specifically, the second target acceleration αt is obtained by adding the product hαf of the preceding vehicle acceleration αf calculated in the previous S130 and the gain h to the first target acceleration αo calculated in S620 (4). Calculated from the formula.

αt = αo + hαf (4)
The gain h is a value determined by experiment or the like, and is set to h = 0.6 (acceleration mode) and 0.8 (deceleration mode) in the present embodiment, for example.

Finally, in subsequent S660, the target acceleration is set to the second target acceleration αt calculated in the previous S650, and the target acceleration calculation process is terminated.
That is, in this target acceleration calculation processing, if the travel mode is set to the follow mode, the target acceleration is set to the first target acceleration αo, and if the travel mode is set to either the acceleration mode or the deceleration mode, the target acceleration is set. The acceleration is set to the second target acceleration αt. However, the upper limit value of the target acceleration αt in the deceleration mode is 0.

  As shown in FIGS. 8 and 9, there is no condition for switching from the acceleration mode to the follow-up mode when the preceding vehicle acceleration αf is positive. This is a two-dimensional map used in the target acceleration calculation process. This is because such a setting is not required.

  8 and 9, in the acceleration mode, if the preceding vehicle acceleration αf becomes smaller than −0.05, it seems that the acceleration mode is immediately switched to the deceleration mode. The tracking mode is maintained at least during the control cycle T, and then the mode is switched to the deceleration mode.

  In the above embodiment, the vehicle speed sensor 3a is the vehicle speed detection means, the front recognition sensor 1 is the preceding vehicle information detection means, S130 is the acceleration calculation means, S610 to S640 are the first target acceleration setting means, and S610 to S630, S650, S660. Is the second target acceleration setting means, S140 is the travel mode switching means, the inter-vehicle control ECU 2 is the inter-vehicle distance control means, and the engine ECU 3 and the brake ECU 4 are the driving force adjusting means.

<Effect>
As described above, in the travel control device of the present embodiment, even if the relative speed Vr is equal to or higher than the set speed (2 [km / s]), if the preceding vehicle acceleration αf is negative, the travel mode is set. Is not switched from the follow-up mode to the acceleration mode (see FIG. 8).

Therefore, according to the travel control device of the present embodiment, it is possible to prevent the switching to the acceleration mode from occurring even though the preceding vehicle is decelerating.
Further, in the travel control device of the present embodiment, even if the preceding vehicle acceleration αf is non-negative and the relative speed Vr is equal to or higher than the set speed (2 [km / s]), the state remains at the set time ( The travel mode setting is not switched from the follow mode to the acceleration mode unless it continues for 3 × T [s]) or more (see FIG. 8).

Therefore, according to the travel control device of the present embodiment, it is possible to prevent mode switching from being repeated frequently when traveling at a relative speed Vr close to the set speed.
Further, in the travel control device of the present embodiment, the relative speed Vr is positive (that is, the collision time Tc is negative) when the preceding vehicle acceleration exceeds the lower limit acceleration (0.045 G [m / s ² ]). In this case, of course, if the relative distance D with the preceding vehicle is sufficiently large (that is, if the collision time Tc is equal to or longer than the lower limit time (30 [s])), even if the relative speed Vr is negative, the travel mode Is immediately switched from the follow-up mode to the acceleration mode (see FIG. 9).

Therefore, according to the travel control device of the present embodiment, when a preceding vehicle at a sufficiently long distance starts to accelerate, the preceding vehicle can follow the preceding vehicle with good responsiveness.
<Other embodiments>
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it is possible to implement in various aspects.

  For example, in each traveling mode switching determination process executed in S220 to S240, the preset threshold values of the relative speed Vr, the collision time Tc, and the preceding vehicle acceleration αf may be changed as appropriate.

  Further, only one of the determination process (that is, the third switching condition) executed in the previous S511 to S515 or the determination process that is executed in S521 to S525 and S540 (that is, the second switching condition) is performed. You may make it perform. Furthermore, it is good also as a process (namely, 1st switching condition) which abbreviate | omitted the judgment using a continuation state counter in S521-S525, S540.

The block diagram which shows the structure of the traveling control apparatus with which this invention was applied. The flowchart which shows the content of the main process which vehicle control ECU performs. The flowchart which shows the detail of the driving mode determination process shown during the process of FIG. The flowchart which shows the detail of the acceleration mode switching determination process shown during the process of FIG. The flowchart which shows the detail of the deceleration mode switching determination process shown during the process of FIG. The flowchart which shows the detail of the follow-up mode switching determination process shown during the process of FIG. The flowchart which shows the detail of the target acceleration calculating process shown during the process of FIG. The graph which shows the driving mode area | region based on relative speed Vr and preceding vehicle acceleration (alpha) f. The graph which shows the driving mode area | region based on collision time Tc and preceding vehicle acceleration (alpha) f.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Front recognition sensor, 2 ... Inter-vehicle control ECU, 2a ... Alarm buzzer, 2b ... Switch, 3 ... Engine ECU, 3a ... Vehicle speed sensor, 4 ... Brake ECU, 4a ... Steering sensor, 4b ... Yaw rate sensor, 5 ... Meter ECU .

Claims (6)

Driving force adjusting means for adjusting the driving force transmitted from the engine to the wheels without depending on the operation of the driver;
Vehicle speed detection means for detecting the vehicle speed of the host vehicle;
Preceding vehicle information detection means for detecting the relative distance and relative speed of the preceding vehicle with respect to the host vehicle;
Acceleration calculation means for calculating the acceleration of the preceding vehicle based on the host vehicle speed detected by the vehicle speed detection means and the relative speed detected by the preceding vehicle information detection means;
Based on the relative distance and relative speed detected by the preceding vehicle information detecting means, a first target for setting a first target acceleration for making the inter-vehicle distance to the preceding vehicle coincide with a preset target inter-vehicle distance. Acceleration setting means;
Second target acceleration setting means for setting a second target acceleration obtained by adding an additional acceleration set according to the preceding vehicle acceleration calculated by the acceleration calculating means to the first target acceleration;
Inter-vehicle distance control having a plurality of travel modes including at least a follow-up mode for controlling the driving force adjusting means using the first target acceleration and an acceleration mode for controlling the driving force adjusting means using the second target acceleration. Means,
Travel mode switching means for switching the travel mode based on detection results of the preceding vehicle information detection means and acceleration calculation means;
In the travel control device comprising:
The travel mode switching means has a first function that the preceding vehicle acceleration calculated by the acceleration calculating means is non-negative and the relative speed detected by the preceding vehicle information detecting means is equal to or higher than a preset set speed. When the first switching condition is satisfied as a switching condition, the traveling control device performs switching from the follow-up mode to the acceleration mode. The travel control device according to claim 1,
A travel control device characterized in that a set speed of the first switching condition is 2 [km / h]. In the traveling control device according to claim 1 or 2,
The travel mode switching means uses the second switching condition as a second switching condition that a state in which the preceding vehicle acceleration is non-negative and the relative speed is equal to or higher than the set speed continues for a preset set time. When the condition is satisfied, the traveling control device switches from the follow mode to the acceleration mode. In the travel control device according to any one of claims 1 to 3,
The travel mode switching means has a sign of a ratio between a relative distance and a relative speed detected by the preceding vehicle information detecting means, and the preceding vehicle acceleration calculated by the acceleration calculating means exceeds a preset lower limit acceleration. When the inverted collision time is negative or equal to or longer than a preset lower limit time, the switching from the follow-up mode to the acceleration mode is performed even when the third switching condition is satisfied. A travel control device. Driving force adjusting means for adjusting the driving force transmitted from the engine to the wheels without depending on the operation of the driver;
Vehicle speed detection means for detecting the vehicle speed of the host vehicle;
Preceding vehicle information detection means for detecting the relative distance and relative speed of the preceding vehicle with respect to the host vehicle;
Acceleration calculation means for calculating the acceleration of the preceding vehicle based on the host vehicle speed detected by the vehicle speed detection means and the relative speed detected by the preceding vehicle information detection means;
Based on the relative distance and relative speed detected by the preceding vehicle information detecting means, a first target for setting a first target acceleration for making the inter-vehicle distance to the preceding vehicle coincide with a preset target inter-vehicle distance. Acceleration setting means;
Second target acceleration setting means for setting a second target acceleration obtained by adding an additional acceleration set according to the preceding vehicle acceleration calculated by the acceleration calculating means to the first target acceleration;
Inter-vehicle distance control having a plurality of travel modes including at least a follow-up mode for controlling the driving force adjusting means using the first target acceleration and an acceleration mode for controlling the driving force adjusting means using the second target acceleration. Means,
Travel mode switching means for switching the travel mode based on detection results of the preceding vehicle information detection means and acceleration calculation means;
In the travel control device comprising:
The traveling mode switching means has a sign of a ratio between the relative distance and the relative speed detected by the preceding vehicle information detecting means, and the preceding vehicle acceleration calculated by the acceleration calculating means exceeds a preset lower limit acceleration. Switching from the follow-up mode to the acceleration mode is performed when the third switching condition is satisfied, with the reversed collision time being negative or not less than a preset lower limit time. A travel control device. In the traveling control device according to claim 4 or 5,
The travel control device characterized in that the lower limit acceleration is 0.045 G [m / s ² ].

Images