JP7442929B2 - Follow-up travel control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a follow-up travel control device that causes a vehicle to follow a preceding vehicle.

Recent vehicles have been equipped with a so-called adaptive cruise control (ACC) function, which allows the vehicle to follow the vehicle in front.

During follow-up driving using the ACC function, a target inter-vehicle distance between the own vehicle and the preceding vehicle is set based on the own vehicle's vehicle speed, and the target inter-vehicle distance is subtracted from the actual inter-vehicle distance to calculate the inter-vehicle distance deviation (= inter-vehicle distance - target inter-vehicle distance). distance) is required. Additionally, the relative speed between the host vehicle and the preceding vehicle is determined. Then, a target acceleration of the own vehicle is set according to the inter-vehicle distance deviation and relative speed, and the output of the engine of the own vehicle or the braking force of the friction brake is controlled so that the own vehicle accelerates or decelerates at the target acceleration.

As shown in FIG. 5, the target acceleration is set to a larger value in the negative direction (deceleration direction) as the inter-vehicle distance deviation becomes smaller. Therefore, when the relative speed between your vehicle and the preceding vehicle is close to 0, but the following distance deviation is small, that is, the target following distance is large compared to the actual value of the following distance, the following distance is In order to free up space, the ACC function applies strong brakes and the vehicle suddenly decelerates. This does not mean that your vehicle is getting closer to the vehicle in front and the following distance has become shorter, so if your vehicle is being followed by another vehicle, the driver of that vehicle may have to apply the brakes because the vehicle in front of you is in danger. Without thinking that it has activated, your vehicle may be rear-ended by a vehicle following you.

Japanese Unexamined Patent Publication No. 61-102335

An object of the present invention is to reduce the risk that the own vehicle will be rear-ended by a following vehicle when a situation occurs in which the relative speed between the own vehicle and the preceding vehicle is close to 0 but the distance deviation between the vehicles is small. An object of the present invention is to provide a follow-up travel control device that can perform the following tasks.

In order to achieve the above-mentioned object, a following cruise control device according to one aspect of the present invention moves the own vehicle to the preceding vehicle so that the following distance between the own vehicle and the preceding vehicle is maintained at the target inter-vehicle distance. A tracking cruise control device that executes tracking cruise control that causes the vehicle to travel while following the vehicle, and includes an operating means that is operated to instruct the start of the tracking cruise control, and an operation means that is operated in a situation where a preceding vehicle is present in front of the own vehicle. Friction brake suppression means for suppressing the operation of the friction brake of the own vehicle when the start of follow-up control is instructed by operation of the means, provided that it is determined that there is no risk of the own vehicle colliding with a preceding vehicle. including.

According to this configuration, an instruction to start tracking control in a situation where there is a preceding vehicle in front of the own vehicle is issued when the own vehicle is traveling to follow the preceding vehicle due to the driver's driving operation at the time of the instruction. This is often done in situations where the relative speed between the host vehicle and the preceding vehicle is close to zero. In this case, even though the relative speed between the host vehicle and the preceding vehicle is close to 0, the following distance deviation, which is the value obtained by subtracting the target following distance from the distance between the own vehicle and the preceding vehicle, is small. By suppressing the operation of the own vehicle's friction brake, the risk of the own vehicle being rear-ended by a following vehicle can be reduced.

Further, the following travel control device according to another aspect of the present invention causes the own vehicle to follow the preceding vehicle so that the inter-vehicle distance between the own vehicle and the preceding vehicle is maintained at the target inter-vehicle distance. A tracking cruise control device that executes tracking cruise control, which includes an operation means operated to switch between a relatively long target inter-vehicle distance setting and a relatively short target inter-vehicle distance setting, and a following cruise control device. When the vehicle is running following the vehicle in front and the setting is switched from a short setting to a long setting by operating the operating means, it is determined that there is no risk of the vehicle colliding with the vehicle in front. and a friction brake suppressing means for suppressing the operation of the friction brake of the own vehicle under the condition that:

According to this configuration, in a situation where the own vehicle is running following the preceding vehicle by executing the follow-up driving control, the relative speed between the own vehicle and the preceding vehicle is close to zero. In this situation, if the target inter-vehicle distance setting is switched from a short setting to a long setting, the target inter-vehicle distance will change from the inter-vehicle distance between the own car and the preceding car, even though the relative speed between the own car and the preceding car is close to 0. Although this situation results in a small inter-vehicle distance deviation, which is the value obtained by subtracting , the risk of the own vehicle being rear-ended by a following vehicle can be reduced by suppressing the operation of the own vehicle's friction brake.

A follow-up travel control device according to still another aspect of the present invention provides a follow-up driving control device that causes the own vehicle to follow the preceding vehicle so that the distance between the own vehicle and the preceding vehicle is maintained at a target inter-vehicle distance. A tracking cruise control device that executes cruise control, which includes an operation means operated to enable and disable the tracking cruise control, and a control device that controls when a preceding vehicle is in front of the own vehicle in a situation where the following cruise control is enabled. or friction brake suppressing means for suppressing the operation of the friction brake of the own vehicle when the vehicle appears due to a change in course of the preceding vehicle, provided that it is determined that there is no risk of the own vehicle colliding with the preceding vehicle.

According to this configuration, when a preceding vehicle appears in front of the own vehicle due to a course change of the own vehicle or the preceding vehicle, the relative speed between the own vehicle and the appearing preceding vehicle is often close to zero. Therefore, if the distance between your vehicle and the preceding vehicle is short, the value calculated by subtracting the target distance from the distance between your vehicle and the preceding vehicle, even though the relative speed between your vehicle and the preceding vehicle is close to 0. However, by suppressing the operation of the own vehicle's friction brake, the risk of the own vehicle being rear-ended by a following vehicle can be reduced.

The follow-up cruise control device may further include a braking device that brakes the host vehicle by a method other than operating the friction brake when the friction brake suppressing device suppresses the operation of the friction brake.

With this configuration, since the own vehicle is prevented from approaching the preceding vehicle, the risk of the own vehicle colliding with the preceding vehicle can be reduced.

According to the present invention, when a situation occurs where the relative speed between the own vehicle and the preceding vehicle is close to 0 but the inter-vehicle distance deviation is small, the risk of the own vehicle being rear-ended by the following vehicle is reduced. be able to.

FIG. 1 is a block diagram showing the configuration of main parts of a vehicle equipped with a follow-up cruise control device according to an embodiment of the present invention. It is a flowchart which shows the flow of ACC brake suppression processing. It is a flow chart which shows the flow of ACC brake suppression processing concerning a 2nd embodiment. It is a flow chart which shows the flow of ACC brake suppression processing concerning a 3rd embodiment. FIG. 3 is a diagram conceptually showing the relationship between inter-vehicle distance deviation, relative speed, and target acceleration.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

<Vehicle electrical configuration>
FIG. 1 is a block diagram showing the configuration of main parts of a vehicle 1 equipped with a follow-up cruise control device according to an embodiment of the present invention.

The vehicle 1 is an automobile that uses an engine 2 as a driving source. The power of the engine 2 is transmitted to the left and right drive wheels via the transmission. The transmission may be a continuously variable transmission (CVT), a stepped automatic transmission (AT), or a manual transmission (MT). ).

The engine 2 is, for example, a gasoline engine, and includes an electronic throttle valve for adjusting the amount of intake air into the combustion chamber of the engine 2, an injector (fuel injection device) for injecting fuel into the intake air, and an electric discharge in the combustion chamber. A spark plug or the like is provided to generate the spark. Further, the engine 2 is provided with a starter for starting the engine.

In the cabin of the vehicle 1, an accelerator pedal that is operated to accelerate or decelerate the vehicle 1 and a brake pedal that is operated to brake the vehicle 1 are provided under the feet of the driver's seat. The accelerator pedal and the brake pedal are located at positions convenient for the driver seated in the driver's seat to operate them with his or her right foot.

Further, the vehicle 1 is equipped with a hydraulic brake. The hydraulic brake includes a brake booster, a master cylinder, and a brake actuator 3. When the brake pedal is depressed, the pedal force input to the brake pedal is transmitted to the brake booster. The pedal force transmitted to the brake booster is amplified (boosted) by the negative pressure of the brake booster, and is input from the brake booster to the master cylinder. In the master cylinder, hydraulic pressure is generated according to the force input from the brake booster. The hydraulic pressure generated by the master cylinder is transmitted to the brake actuator 3. The function of the brake actuator 3 distributes hydraulic pressure to the wheel cylinders of the brakes provided on each wheel, and the hydraulic pressure applies braking force from each brake to the wheels including the driving wheels.

The vehicle 1 is equipped with an ECU (Electronic Control Unit) 4 that includes a microcomputer (microcontroller unit). A microcomputer includes, for example, a CPU, a nonvolatile memory such as a flash memory, and a volatile memory such as a DRAM (Dynamic Random Access Memory). Although only one ECU 4 is shown in FIG. 1, the vehicle 1 is equipped with a plurality of ECUs having the same configuration as the ECU 4 in order to control each part. A plurality of ECUs including the ECU 4 are connected to enable bidirectional communication using a CAN (Controller Area Network) communication protocol.

The ECU 4 incorporates engine control logic and brake control logic. The engine control logic adjusts the start, stop, output, etc. of the engine 2 based on detection signals input from various sensors connected to the ECU 4 and information input from other ECUs, so the electronic throttle valve, injector, etc. and spark plugs, etc. are controlled. The brake actuator 3 and the like are controlled by the brake control logic in order to adjust the vehicle speed, attitude, etc. of the vehicle 1 based on detection signals input from various sensors and information input from other ECUs.

The various sensors include, for example, a vehicle speed sensor 5 and a preceding vehicle detection sensor 6.

The vehicle speed sensor 5 includes, for example, a rotor made of a magnetic material that rotates as the vehicle 1 travels, and an electromagnetic pickup provided in a non-contact manner with the rotor, and receives an output from the electromagnetic pickup each time the rotor rotates by a certain angle. Outputs a pulse signal. The frequency of this pulse signal corresponds to the actual speed of the vehicle 1. The ECU 4 determines the frequency of the signal input from the vehicle speed sensor 5, and converts the frequency into a vehicle speed.

The preceding vehicle detection sensor 6 is a sensor that detects a preceding vehicle ahead of the vehicle 1, and is, for example, a radar. The radar is installed at the front of the vehicle 1 and is a sensor for detecting the situation in a predetermined search range in front of the vehicle 1. A radar irradiates a search range with radar waves, receives reflected waves from objects existing within the search range, and outputs a detection signal according to the reflected waves. The radar may be a millimeter wave radar that uses radio waves in the millimeter wave band as radar waves, or a laser radar that uses a laser as radar waves. Moreover, an ultrasonic sensor or a stereo camera may be employed as the preceding vehicle detection sensor 6.

The vehicle 1 is equipped with an adaptive cruise control (ACC) function as a driving support function.

The ACC function is a follow-up driving function that causes the vehicle 1 to follow a preceding vehicle, which is another vehicle ahead of the vehicle 1. For example, the steering wheel is provided with an operation switch 7 related to the ACC function. The operation switch 7 includes an ACC main switch that turns on/off the ACC function, a set switch that sets the current vehicle speed of the vehicle 1 as a set vehicle speed, a set distance changeover switch that changes the length of the distance between the vehicle 1 and the preceding vehicle, and It includes a cancel switch that deactivates the ACC function and a resume switch that reactivates the ACC function at the previously set vehicle speed.

When the ACC main switch is pressed, the ACC function is activated. Thereafter, when the set switch is pressed, the current vehicle speed of the vehicle 1 is set to the set vehicle speed. The set vehicle speed can be changed by pressing a resume switch or a set switch. That is, by pressing the resume switch, the set vehicle speed can be increased, and by pressing the set switch, the set vehicle speed can be decreased. Further, by pressing the set inter-vehicle distance changeover switch, for example, it is possible to switch between setting the inter-vehicle distance to a longer distance, a shorter distance, or an intermediate value.

When the set vehicle speed is set, the ECU 4 starts ACC control (follow-up travel control) that causes the vehicle 1 to travel while following the preceding vehicle in front of it. In ACC control, depending on the presence or absence of a preceding vehicle, the vehicle is automatically switched between following the preceding vehicle with the upper limit vehicle speed set at a vehicle speed set by operating a switch, and constant-speed traveling at the set vehicle speed. During follow-up driving, the vehicle 1 is accelerated or decelerated so that the distance between the vehicle 1 and the preceding vehicle in front of it is maintained at the target distance. Specifically, a target inter-vehicle distance between vehicle 1 and the preceding vehicle is set based on the vehicle speed of vehicle 1, and the inter-vehicle distance deviation between the target inter-vehicle distance and the actual inter-vehicle distance (=actual inter-vehicle distance - target inter-vehicle distance) is required. Additionally, the relative speed between the vehicle 1 and the preceding vehicle is determined. Then, a target acceleration of the vehicle 1 is set according to the inter-vehicle distance deviation and relative speed, and the output of the engine or the braking force of the brake is controlled so that the vehicle 1 accelerates or decelerates at the target acceleration.

<ACC brake suppression processing>
FIG. 2 is a flowchart showing the flow of the ACC brake suppression process.

While the vehicle 1 is running, the ECU 4 executes ACC brake suppression processing at a predetermined cycle.

In the ACC brake suppression process, first, it is determined whether the ACC control is started in a situation where a preceding vehicle exists near the front of the vehicle 1 (self-vehicle) (step S11). ACC control is started in response to the set vehicle speed being set by pressing the set switch or resume switch, so whether or not ACC control has been started can be determined by determining whether the set switch or resume switch has been pressed. This is equivalent to a judgment of whether or not.

When ACC control is started in a situation where a preceding vehicle exists near the front of vehicle 1 (YES in step S11), it is then determined whether the inter-vehicle distance between vehicle 1 and the preceding vehicle is less than a predetermined distance. (Step S12). If the vehicle 1 is far away from the preceding vehicle and the inter-vehicle distance is equal to or greater than the predetermined distance (NO in step S12), the hydraulic brake is activated by ACC control (hereinafter referred to as "ACC brake activation") and the engine is activated. The ACC brake suppression process ends without decelerating the vehicle 1 by operating the brakes.

If vehicle 1 is close to the preceding vehicle and the inter-vehicle distance between vehicle 1 and the preceding vehicle is less than a predetermined distance (YES in step S12), it is determined whether relative speed is occurring in the direction in which vehicle 1 approaches the preceding vehicle. In other words, it is determined whether the vehicle 1 is approaching the preceding vehicle (step S13).

If the relative speed in the direction in which the vehicle 1 approaches the preceding vehicle is not occurring (NO in step S13), it is determined whether the ACC brake is already in operation (step S14).

If the ACC brake is not in operation (NO in step S14), it is determined whether the vehicle 1 is traveling downhill (step S15).

If the vehicle 1 is not traveling downhill (NO in step S15), it is determined whether the own vehicle speed, which is the vehicle speed of the vehicle 1, is less than a predetermined vehicle speed (step S16). The predetermined vehicle speed is the vehicle speed at which the vehicle 1 is about to stop, and is set, for example, to a vehicle speed within a range of 5 to 10 km/h.

If the own vehicle speed is not less than the predetermined vehicle speed (NO in step S16), that is, if the own vehicle speed is greater than or equal to the predetermined vehicle speed, the hydraulic brake is not activated (ACC brake is not activated), and the engine 2 reduces the resistance to the running of the vehicle 1. By the engine brake (engine brake operation), the vehicle 1 is decelerated at the target acceleration (step S17), and the ACC brake suppression process is ended.

On the other hand, if vehicle 1 is approaching the preceding vehicle (YES in step S13), if the ACC brake is in operation (YES in step S14), or if vehicle 1 is traveling downhill (YES in step S15), the ACC brake is in operation (YES in step S14). YES), or if the own vehicle speed is less than the predetermined vehicle speed (YES in step S16), the operation of the ACC brake is determined and the brake actuator 3 is controlled so that the vehicle 1 decelerates at the target acceleration. , braking force by the hydraulic brake is applied to the wheels (step S18). Then, the ACC brake suppression process is ended.

<Effect>
As described above, when starting ACC control in a situation where there is a preceding vehicle near the front of vehicle 1, vehicle 1 follows the preceding vehicle due to the driver's driving operation, and the relative relationship between vehicle 1 and the preceding vehicle is The speed is often close to 0. In this case, although the relative speed between vehicle 1 and the preceding vehicle is close to 0, the following distance deviation, which is the value obtained by subtracting the target following distance from the inter-vehicle distance between vehicle 1 and the preceding vehicle, is small. However, when the relative speed in the direction in which vehicle 1 approaches the preceding vehicle is not occurring, the ACC brake is not in operation, vehicle 1 is not traveling downhill, and the own vehicle speed is not less than the predetermined vehicle speed. It can be determined that there is no risk of the vehicle 1 colliding with the preceding vehicle, and in that case, the operation of the hydraulic brake (friction brake) of the vehicle 1 is suppressed and the ACC brake is deactivated. Thereby, the risk that the vehicle 1 will be rear-ended by a following vehicle can be reduced.

<Second embodiment>
FIG. 3 is a flowchart showing the flow of ACC brake suppression processing according to the second embodiment.

The ACC brake suppression process shown in FIG. 3 may be executed by the ECU 4 while the vehicle 1 is running in place of the ACC brake suppression process shown in FIG. 2, or may be executed independently of the ACC brake suppression process shown in FIG. may be executed in parallel.

In the ACC brake suppression process shown in FIG. 3, the set distance changeover switch of the operation switch 7 is operated during follow-up driving under ACC control, and the setting of the following distance (set distance) is set relatively short. It is determined whether the setting has been changed to a longer setting (step S21). When the set vehicle distance is changed from a shorter setting to a longer setting (YES in step S21), subsequent steps S22 to S28 are executed. Steps S22 to S28 are the same as steps S11 to S18 shown in FIG. 2 described above, respectively, so their explanation will be omitted.

<Effect>
As described above, in a situation where the vehicle 1 is running following the preceding vehicle under the ACC control, the relative speed between the vehicle 1 and the preceding vehicle is close to zero. In this situation, when the set inter-vehicle distance is switched from a short setting to a long setting, the target inter-vehicle distance is subtracted from the inter-vehicle distance between vehicle 1 and the preceding vehicle, even though the relative speed between vehicle 1 and the preceding vehicle is close to 0. This is a situation where the inter-vehicle distance deviation, which is the value, is small. However, when vehicle 1 is not approaching the preceding vehicle at a relative speed, the ACC brake is not in operation, vehicle 1 is not traveling downhill, and the own vehicle speed is not less than the predetermined vehicle speed. In this case, it can be determined that there is no risk of the vehicle 1 colliding with the preceding vehicle, and in this case, the operation of the hydraulic brake of the vehicle 1 is suppressed and the ACC brake is deactivated. Thereby, the risk that the vehicle 1 will be rear-ended by a following vehicle can be reduced.

<Third embodiment>
FIG. 4 is a flowchart showing the flow of ACC brake suppression processing according to the third embodiment.

The ACC brake suppression process shown in FIG. 4 may be executed by the ECU 4 while the vehicle 1 is running instead of the ACC brake suppression process shown in FIGS. 2 or 3, or the ACC brake suppression process shown in FIGS. The ACC brake suppression process may be executed independently and in parallel with the ACC brake suppression process.

In the ACC brake suppression process shown in FIG. 4, it is determined whether a preceding vehicle has appeared in front of the vehicle 1 with the ACC function set to on (step S31). If a preceding vehicle appears in front of the vehicle 1 (YES in step S31), subsequent steps S32 to S38 are executed. Steps S32 to S38 are the same as steps S11 to S18 shown in FIG. 2 described above, respectively, so the explanation thereof will be omitted.

<Effect>
As described above, when the ACC function is set to on and a preceding vehicle appears in front of vehicle 1 due to a change in the course of vehicle 1 or the preceding vehicle, the relative speed between vehicle 1 and the preceding vehicle that has appeared is often close to 0. Therefore, if the inter-vehicle distance between vehicle 1 and the preceding vehicle is short, the value obtained by subtracting the target inter-vehicle distance from the inter-vehicle distance between vehicle 1 and the preceding vehicle, even though the relative speed between vehicle 1 and the preceding vehicle is close to 0. This results in a situation where the inter-vehicle distance deviation is small. However, when vehicle 1 is not approaching the preceding vehicle at a relative speed, the ACC brake is not in operation, vehicle 1 is not traveling downhill, and the own vehicle speed is not less than the predetermined vehicle speed. In this case, it can be determined that there is no risk of the vehicle 1 colliding with the preceding vehicle, and in this case, the operation of the hydraulic brake of the vehicle 1 is suppressed and the ACC brake is deactivated. Thereby, the risk that the vehicle 1 will be rear-ended by a following vehicle can be reduced.

<Modified example>
Although several embodiments of the present invention have been described above, the present invention can also be implemented in other forms.

For example, in the above-described embodiment, the set vehicle speed is set by pressing the set switch and the resume switch. , a speed limit sign (maximum speed sign) may be recognized from the image taken by the camera, and the speed displayed on the speed limit sign may be set as the set speed.

Further, in the above-described embodiment, the engine control logic and the brake control logic are incorporated in the ECU 4, but the engine ECU that controls the engine 2 and the brake ECU that controls the brake actuator 3 are separately provided. , the functions of the ECU 4 may be realized through cooperation between the engine ECU and the brake ECU.

In addition, various design changes can be made to the above-described configuration within the scope of the claims.

1: Vehicle (own car)
2: Engine (braking means)
3: Brake actuator (friction brake)
4: ECU (Following travel control device, friction brake suppression means)
7: Operation switch (operation means)

Claims (4)

A follow-up travel control device that executes follow-up travel control for causing the host vehicle to follow the preceding vehicle so that the distance between the host vehicle and the preceding vehicle is maintained at a target inter-vehicle distance,
an operating means operated to instruct the start of the follow-up travel control;
When the start of the following driving control is instructed by operating the operating means in a situation where the preceding vehicle is present in front of the own vehicle , a relative speed is generated in a direction in which the own vehicle approaches the preceding vehicle. the own vehicle, the friction brake of the own vehicle is not in operation, the own vehicle is not traveling downhill, and the own vehicle speed is determined to be equal to or higher than a predetermined vehicle speed. a friction brake suppressing means for suppressing operation of a friction brake of the following cruise control device. A follow-up travel control device that executes follow-up travel control for causing the host vehicle to follow the preceding vehicle so that the distance between the host vehicle and the preceding vehicle is maintained at a target inter-vehicle distance,
an operating means operated to switch between a relatively long setting and a relatively short setting of the target inter-vehicle distance;
When the own vehicle is running following the preceding vehicle by executing the following driving control and the short setting is switched to the long setting by operating the operating means , the own vehicle is traveling in the following state. If a relative speed in a direction approaching the preceding vehicle is not occurring, the friction brake of the own vehicle is not in operation, the own vehicle is not traveling downhill, and the own vehicle speed is equal to or higher than a predetermined vehicle speed. A follow-up travel control device comprising: friction brake suppressing means for suppressing the operation of the friction brake of the own vehicle on the condition that the determination is made. A follow-up travel control device that executes follow-up travel control for causing the host vehicle to follow the preceding vehicle so that the distance between the host vehicle and the preceding vehicle is maintained at a target inter-vehicle distance,
an operating means operated to enable and disable the follow-up travel control;
When the preceding vehicle appears in front of the own vehicle due to a course change of the own vehicle or the preceding vehicle in a situation where the following driving control is effective , the relative speed of the own vehicle in the direction in which the own vehicle approaches the preceding vehicle. has not occurred, the friction brake of the own vehicle is not in operation, the own vehicle is not traveling downhill, and the own vehicle speed is determined to be equal to or higher than a predetermined vehicle speed , A follow-up travel control device, comprising: friction brake suppressing means for suppressing operation of a friction brake of the host vehicle. 4. The vehicle according to claim 1, further comprising a braking means for braking the host vehicle by a method other than the operation of the friction brake when the friction brake suppressing means suppresses the operation of the friction brake. The follow-up travel control device described.

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