JP2014024486A - Drive support device and drive support method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a vehicle to travel with reduced speed fluctuation while maintaining an adequate inter-vehicle distance from a leading vehicle.SOLUTION: A drive support ECU 1 is provided with: a propagation time calculation section which calculates propagation time for influence of speed fluctuation of a leading vehicle travelling ahead an own vehicle to be propagated to the own vehicle or the vehicle travelling immediately in front of the own vehicle; an averaging time calculation section to set averaging time, to be used for calculating an average speed of the leading vehicle, to double the propagation time; an average speed calculation section which calculates the average speed of the leading vehicle using the averaging time; a target speed calculation section which calculates a target speed of the own vehicle on the basis of the average speed; and a braking power control section which performs braking power control with target drive power and target braking power of the own vehicle according to the target speed.

Description

  The present invention relates to a driving support device and a driving support method for driving a host vehicle in accordance with driving conditions of a plurality of vehicles ahead.

  Conventionally, this type of driving support apparatus and driving support method are known. For example, in Patent Document 1 below, the speeds of a plurality of vehicles traveling in front of the host vehicle are acquired, and the average speed and the vehicle density of each vehicle (the degree of congestion of the host vehicle and the vehicles ahead). A technique for determining the control speed of the vehicle based on the above is disclosed. According to the technique of this patent document 1, the own vehicle can suppress the frequency of acceleration / deceleration traveling so as to follow only the immediately preceding vehicle, and can travel at a constant speed at a control speed corresponding to the average speed of a plurality of vehicles ahead. can do. In Patent Document 2 below, inter-vehicle distances with a plurality of vehicles traveling in front of the host vehicle are acquired, fluctuations in the inter-vehicle distance between the host vehicle and the preceding vehicle, and further A technique for performing follow-up traveling with respect to a preceding vehicle by causing the host vehicle to accelerate and decelerate based on the inter-vehicle distance with the other vehicle is disclosed.

JP 2010-274839 A JP 2001-199257 A

  By the way, in the conventional technology, when the speeds of all the vehicles traveling in front of the own vehicle cannot be obtained, or the inter-vehicle distances with all the vehicles traveling in front of the own vehicle are grasped. If this is not possible, there is a possibility that the optimum control speed and control acceleration / deceleration of the host vehicle in accordance with the traveling state of each vehicle ahead cannot be obtained. In that case, there is a possibility that the vehicle is too far away or too close to the vehicle immediately before.

  Accordingly, the present invention provides a driving support device and a driving support method capable of improving the disadvantages of the conventional example and capable of traveling while suppressing a speed fluctuation while maintaining an appropriate inter-vehicle distance from the immediately preceding vehicle. For that purpose.

  In order to achieve the above-described object, the driving support apparatus according to the present invention allows the influence of the speed change of the forward vehicle traveling in front of the host vehicle to be propagated to the host vehicle or the preceding vehicle traveling immediately before the host vehicle. A propagation time calculation unit that calculates the propagation time of the vehicle, an averaging time calculation unit that doubles the average time used for calculating the average speed of the vehicle ahead, and the front using the averaging time. An average speed calculation unit that calculates an average speed of the vehicle, a target speed calculation unit that calculates a target speed of the host vehicle based on the average speed, and a target driving force and a target braking force of the host vehicle according to the target speed. And a braking / driving force control unit that performs braking / driving force control.

  Here, when there is a phase difference between the speed of the own vehicle or the speed of the preceding vehicle and the average speed of the preceding vehicle, the averaging time calculation unit reduces the phase difference or eliminates the phase difference. It is desirable to correct the averaging time.

  In addition, it is preferable that the averaging time calculation unit lengthens the averaging time as the number of front vehicles increases.

  In order to achieve the above object, the driving support method according to the present invention transmits the influence of the speed change of the preceding vehicle traveling in front of the own vehicle to the own vehicle or the preceding vehicle traveling immediately before the own vehicle. A step of calculating a propagation time until a predetermined time, a step of doubling an average time used for calculating an average speed of the preceding vehicle, and an average speed of the preceding vehicle using the average time. A step of calculating, a step of calculating a target speed of the host vehicle based on the average speed, and a step of performing braking / driving force control with the target driving force and the target braking force of the host vehicle according to the target speed. It is characterized by that.

  Here, when there is a phase difference between the speed of the own vehicle or the speed of the preceding vehicle and the average speed of the preceding vehicle, the averaging time is corrected so as to reduce the phase difference or eliminate the phase difference. It is desirable to provide a process for performing the above.

  In addition, it is desirable to provide a step of increasing the averaging time as the number of front vehicles increases.

  The driving support device and the driving support method according to the present invention average the speed of the preceding vehicle with an averaging time that is twice the propagation time, and use the average speed of the preceding vehicle as the target speed of the host vehicle. The phase of the target speed of the own vehicle can be brought close to the phase of the speed of the preceding vehicle. Therefore, the host vehicle can travel with the speed fluctuation suppressed while maintaining the inter-vehicle distance from the preceding vehicle without a sense of incongruity.

FIG. 1 is a diagram illustrating an example of a vehicle to which a driving support device and a driving support method according to the present invention are applied. FIG. 2 is a diagram illustrating waveforms of speed changes of the host vehicle and the preceding vehicle. FIG. 3 is a diagram showing a waveform of the average speed of the preceding vehicle together with the waveform of the speed change of FIG. FIG. 4 is a flowchart for explaining a calculation processing operation of the driving support device and the driving support method of the embodiment. FIG. 5 is a diagram illustrating a comparison result between the speed of the own vehicle (target speed) and the speed of the preceding vehicle when the averaging time is twice the propagation time, and the inter-vehicle distance between the own vehicle and the preceding vehicle. FIG. 6 is a diagram illustrating a comparison result of the speed of the preceding vehicle, the average speed of the preceding vehicle, and the speed of the preceding vehicle when the averaging time is twice the propagation time. FIG. 7 is a diagram illustrating a result of comparison between the speed of the own vehicle (target speed) and the speed of the preceding vehicle when the averaging time is four times the propagation time, and the inter-vehicle distance between the own vehicle and the preceding vehicle. FIG. 8 is a diagram illustrating a result of comparison between the speed of the own vehicle (target speed) and the speed of the preceding vehicle when the averaging time is the propagation time, and the inter-vehicle distance between the own vehicle and the preceding vehicle. FIG. 9 is a diagram illustrating a comparison result of the speed of the preceding vehicle, the average speed of the preceding vehicle, and the speed of the preceding vehicle when the averaging time is four times the propagation time. FIG. 10 is a diagram illustrating a comparison result between the speed of the preceding vehicle, the average speed of the preceding vehicle, and the speed of the preceding vehicle when the averaging time is the propagation time. FIG. 11 is a flowchart for explaining the arithmetic processing operation of the driving support apparatus and driving support method of the first modification. FIG. 12 is a diagram for explaining the speed fluctuation of the vehicle behind the long train when the averaging time is twice as long as the propagation time. FIG. 13 is a flowchart for explaining a calculation processing operation of the driving support device and the driving support method according to the second modification. FIG. 14 is a diagram for explaining the own vehicle and the preceding vehicle in a long row. FIG. 15 is a diagram for explaining the effect of suppressing the speed fluctuation of the vehicle behind the long row when averaged by the averaged time after correction of the second modification.

  Embodiments of a driving support apparatus and a driving support method according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the embodiments.

[Example]
Embodiments of a driving support apparatus and a driving support method according to the present invention will be described with reference to FIGS.

  The driving support apparatus and driving support method of the present embodiment are an apparatus and a method that perform driving support for driving the host vehicle in accordance with the driving state of a plurality of vehicles ahead. For example, this driving support apparatus and driving support method obtains a target speed and a target acceleration / deceleration of the own vehicle based on at least one traveling state of a plurality of vehicles traveling in front of the own vehicle. The braking / driving force of the vehicle is controlled according to the target acceleration / deceleration. Some of the driving support devices and driving support methods notify the driver of the vehicle of the target speed and prompt the vehicle to travel at the target speed. In this driving support device and driving support method, the operation is controlled by a driving support electronic control device (hereinafter referred to as “driving support ECU”) 1.

  First, the vehicle 100 to which the driving support device and the driving support method are applied will be described. In the vehicle 100, a traveling state such as braking / driving force is controlled by an electronic control device (hereinafter referred to as “travel control ECU”) 2 for travel control. The travel control ECU 2 is connected to the driving support ECU 1 and can exchange information and commands between them. Here, as shown in FIG. 1, an FF (Front engine Front drive) vehicle is taken as an example.

  The vehicle 100 is provided with a drive device that generates drive torque and transmits the drive torque to the drive wheels Wfl and Wfr.

  The drive device includes a power source 11 that generates drive torque. The power source 11 is an engine, a rotating electric machine, or the like. The engine is a so-called engine such as an internal combustion engine or an external combustion engine. The rotating electric machine is an electric motor, a motor generator or the like. The vehicle 100 has at least one of an engine and a rotating electric machine mounted as the power source 11. The power source 11 is controlled by the travel control ECU 2 and outputs a target drive torque. Examples of the target drive torque include those calculated according to the amount of operation of the accelerator pedal 15 (accelerator opening degree, etc.) by the driver, and those set by the driving support ECU 1 or the travel control ECU 2. The target driving torque set by the driving assistance ECU 1 or the like is a driving torque that the driving assistance ECU 1 or the like obtains as a target value regardless of the amount of operation of the accelerator pedal 15 or the presence or absence of the driver's accelerator operation. For example, it refers to the driving torque of the power source 11 for traveling the host vehicle in accordance with the traveling state of a plurality of vehicles ahead. The operation amount of the accelerator pedal 15 is detected by an accelerator operation amount detection device 31 such as an accelerator opening sensor and transmitted to the travel control ECU 2.

  Further, the drive device includes a power transmission unit including a transmission 12, a differential device 13, and the like that transmit the drive torque of the power source 11 to the drive wheels Wfl and Wfr. The transmission 12 may be a stepped or continuously variable automatic transmission controlled by the travel control ECU 2 or a manual transmission in which the shift stage is determined by a manual operation of the driver. In this example, a vehicle speed detection device (vehicle speed sensor or the like) 32 that detects the speed of the host vehicle based on the rotation angle of the output shaft of the transmission 12 is provided.

  In addition, the vehicle 100 is provided with a braking device that applies a braking torque to each wheel W. The braking device includes a braking unit 21 that applies a braking torque to each wheel W with the hydraulic pressure of the brake fluid, and a brake hydraulic pressure control unit 22 as a hydraulic actuator that can control the hydraulic pressure supplied to the braking unit 21 for each wheel W. . The brake hydraulic pressure control unit 22 can output the master cylinder pressure corresponding to the operation amount of the brake pedal 25 as it is, and can increase or decrease the master cylinder pressure according to a command from the travel control ECU 2. Is possible. That is, the target braking torque to be generated for each wheel W includes one calculated according to the amount of operation of the driver's brake pedal 25, one set by the driving support ECU 1 or the traveling control ECU 2, and the like. The target braking torque set by the driving assistance ECU 1 or the like is a braking torque that the driving assistance ECU 1 or the like obtains as a target value regardless of the amount of operation of the brake pedal 25 or the presence or absence of the driver's braking operation. For example, it refers to braking torque or the like for driving the host vehicle in accordance with the traveling state of a plurality of vehicles ahead. The operation amount of the brake pedal 25 is detected by a brake operation amount detection device 33 such as a pedal opening sensor and transmitted to the travel control ECU 2.

  Here, the vehicle 100 can generate regenerative braking torque when it has a rotating electrical machine. In this case, the target braking torque is realized by at least one of the braking torque by the braking unit 21 and the regenerative braking torque by the rotating electrical machine.

  As described above, the vehicle 100 is provided with a driving support device that causes the host vehicle to travel in accordance with the traveling states of a plurality of vehicles ahead. The driving support device exemplified here supports driving of the own vehicle when a plurality of vehicles such as traffic jams are running in a row. Hereinafter, a vehicle traveling in front of the host vehicle is referred to as a “front vehicle”, and a vehicle traveling immediately before the host vehicle is referred to as a “preceding vehicle”.

  When a certain vehicle in the platoon performs acceleration / deceleration, the braking / driving force of the vehicle immediately behind the vehicle is adjusted by the driving support ECU 1 or the driver or the driver in accordance with the acceleration / deceleration of the preceding vehicle. For example, the vehicle directly behind the vehicle travels while keeping the inter-vehicle distance constant with the preceding vehicle, or accelerates / decelerates while keeping the inter-vehicle distance within a predetermined range without being attached to the vehicle according to the acceleration / deceleration of the preceding vehicle. Or run at a constant speed. Such an influence due to the change in the traveling state of the preceding vehicle propagates not only to the vehicle immediately behind, but also to all subsequent vehicles in the formation.

  FIG. 2 is a diagram showing a waveform of a speed change (speed profile) with the horizontal axis and the vertical axis as time and speed, respectively. The waveform shows the speed change (solid line) of the own vehicle in the platoon affected by the speed change (dashed line) of the preceding vehicle several cars ahead. In the illustration of FIG. 2, since the maximum speed (waveform peak) of the host vehicle is higher than the maximum speed of the preceding vehicle in one cycle, the host vehicle may be too close to the preceding vehicle.

  Therefore, in the driving support device and the driving support method, the target speed change (target speed and target acceleration / deceleration) of the host vehicle is calculated based on the information on the speed change of the preceding vehicle several cars ahead, and along the target speed change Support the driving of the vehicle so that it can run.

  First, a vehicle 100 including this driving support device is provided with a communication device 41 that is controlled by the driving support ECU 1 and transmits / receives information to / from another vehicle. The transmission / reception of the information is performed by vehicle-to-vehicle communication or road-to-vehicle communication. Here, at least vehicle information such as information on the driving state and control parameters for driving support is the object of transmission / reception. The travel state information transmitted by the communication device 41 includes at least the speed of the host vehicle. In addition, the driving assistance control parameter transmitted by the communication device 41 includes at least an averaging time Tave for calculating a target speed of the host vehicle, which will be described later. When the own vehicle has already received the vehicle information of the other vehicle, the communication device 41 of the own vehicle may transmit the vehicle information of the other vehicle together with the information of the own vehicle.

  By the way, the vehicle information of the other vehicle required by the host vehicle in this driving support is information of the preceding vehicle in the platoon running ahead of the host vehicle, and is not information of the subsequent vehicle following the host vehicle. For this reason, it is desirable that the communication device 41 include the vehicle position information acquired by the GPS (Global Positioning System) 42 in the vehicle information. By configuring in this way, the driving assistance ECU 1 of the own vehicle can grasp whether the other vehicle is a front vehicle or a subsequent vehicle based on the position information of the own vehicle and the position information of the other vehicle. it can.

  The driving assistance ECU 1 of the vehicle 100 includes an average speed calculation unit that calculates the average speed Vave of the preceding vehicle based on the received speed information of the preceding vehicle. The forward vehicle that is the object of this calculation is determined from the forward vehicles that exist within a range in which the vehicle can communicate by inter-vehicle communication or the like. Here, the vehicle ahead of the host vehicle does not necessarily have the communication device 41, and even if it has the communication device 41, the vehicle information required by the host vehicle is not necessarily transmitted. For this reason, in this driving support device and driving support method, it is not possible to determine a fixed target to calculate the average speed Vave of the preceding vehicle ahead of the own vehicle, for example, communication with the own vehicle is possible. The average speed Vave of the vehicle closest to the host vehicle is calculated from among the preceding vehicles, and the average speed Vave of the vehicle farthest from the host vehicle among the preceding vehicles that can communicate with the host vehicle is calculated. A forward vehicle suitable for the driving support mode at that time, such as calculating the average speed Vave of the vehicle closest to or farthest from the number of vehicles ahead of or within the number of vehicles that can communicate from the own vehicle The average speed Vave of the preceding vehicle is calculated for the object. As will be described later, the average speed Vave of the preceding vehicle becomes the target speed Vtgt of the own vehicle. Therefore, it can be said that the preceding vehicle for which the average speed Vave is calculated is a vehicle for which the target speed Vtgt of the own vehicle is calculated.

  The average speed calculation unit can calculate the average speed Vave of the preceding vehicle using Equation 1 below. “Tave” in Equation 1 is an averaging time for averaging the speed of the preceding vehicle. “Ω” is an angular frequency. Here, it is assumed that the velocity waveform is a periodic function such as a sine wave.

  The target speed calculation unit of the driving assistance ECU 1 determines a change in the average speed Vave of the preceding vehicle as a change in the target speed Vtgt of the own vehicle. That is, the driving assistance ECU 1 controls the braking / driving force by setting the average speed Vave of the preceding vehicle to the target speed Vtgt of the own vehicle. Therefore, the braking / driving force control unit of the driving assistance ECU 1 calculates the target driving force and the target braking force of the own vehicle according to the target speed Vtgt of the own vehicle, and travels information on the target driving force and the target braking force. It sends to control ECU2. The braking / driving force control unit of the travel control ECU 2 calculates a target driving torque of the power source 11 for applying the target driving force to the own vehicle, and also each wheel W for applying the target braking force to the own vehicle. The target braking torque is calculated. When the transmission 12 of the vehicle 100 is an automatic transmission, the target driving force may be realized by changing the transmission ratio of the transmission 12. In this case, the braking / driving force control unit calculates the target driving torque of the power source 11 and the gear ratio of the transmission 12 necessary for applying the target driving force to the host vehicle. The calculation of the target driving torque or the like may be executed by the braking / driving force control unit of the driving support ECU 1.

  Now, for the sake of convenience, comparison is made between the peaks (maximum speed) of each speed change, but it can be seen that the phase of the speed change of the own vehicle is delayed with respect to the speed change of the preceding vehicle (FIG. 2). The phase delay time is the time required for the host vehicle to be affected by the speed change of the preceding vehicle several cars ahead, and the propagation time T until the effect of the speed change of the preceding vehicle is propagated to the host vehicle. It can be said. Therefore, if the speed of the vehicle ahead is simply averaged, a deviation of, for example, the propagation time T occurs between the phase of the average speed Vave and the speed of the host vehicle.

  Therefore, in this example, in order to handle the average speed Vave of the preceding vehicle as the target speed Vtgt of the own vehicle, the phase of the average speed Vave is brought close to the phase of the own vehicle speed. Here, the phase of the average speed Vave changes depending on the magnitude of the averaging time Tave. For this reason, the driving assistance ECU 1 sets the averaging time Tave for bringing the phase of the average speed Vave of the preceding vehicle close to the phase of the speed of the own vehicle, more preferably the phase of the average speed Vave of the preceding vehicle is set to the phase of the speed of the own vehicle. An averaging time calculation unit that calculates the averaging time Tave to be matched is provided.

  Here, the phase of the average speed Vave of the vehicle ahead is delayed by the propagation time T so that the phase of the average speed Vave matches the phase of the speed of the host vehicle. In other words, the averaging time calculation unit calculates “sin ω (t−T / 2)” as “sin ω (t−T)” in which the expression “sin ω (t−Tave / 2)” represents the delay of the propagation time T Thus, the averaging time Tave for calculating the target speed of the host vehicle may be determined.

  Therefore, the averaging time calculation unit calculates the averaging time Tave that doubles the propagation time T (Tave = 2T). The average speed calculation unit may calculate the average speed Vave of the preceding vehicle based on the following Expression 3 in which “2T” is substituted for “Tave” in Expression 2. In Equation 3, “sin ωT / ωT” is a constant representing the amplitude (maximum speed) of the waveform of the average speed Vave, and is smaller than 1. Further, “sin ω (t−T)” represents a translation of the speed waveform “sin ωt” of the vehicle ahead by the propagation time T.

  The change in the average speed Vave of the preceding vehicle calculated based on the formula 3 or the formula 2 is represented by a one-dot chain line in FIG. In FIG. 3, it can be seen that the peak of the change in the average speed Vave of the preceding vehicle is close to the peak of the change in the speed of the own vehicle, and the phases of the respective change waveforms are approximated. That is, the phase of the change in the average speed Vave approaches the phase of the speed change of the own vehicle. The amplitude (maximum speed) of the change in the average speed Vave is suppressed to be lower than the amplitude of the speed change of the own vehicle. Therefore, the host vehicle sets the change in the average speed Vave to the change in the target speed Vtgt of the host vehicle and performs the braking / driving force control, thereby changing the phase of the target speed Vtgt of the host vehicle to the phase of the speed of the host vehicle ( (Similar to the phase of the speed of the preceding vehicle) and can travel with less acceleration / deceleration than the preceding vehicle.

  In calculating the average velocity Vave, information on the propagation time T is required. The propagation time T varies depending on the state of the convoy such as the speed and inter-vehicle distance of each vehicle in the convoy. For this reason, the driving assistance ECU 1 is provided with a propagation time calculation unit that calculates the propagation time T. This propagation time calculation part calculates | requires propagation time T, for example based on the phase difference of each speed change of the own vehicle and front vehicle of FIG.

  Here, for example, when the preceding vehicle has already traveled corresponding to the average speed Vave in FIG. 3, the phase difference between the speed change of the preceding vehicle and the speed change of the host vehicle is small. There is a possibility that the propagation time T until the influence of the speed change of the preceding vehicle is propagated to the host vehicle cannot be measured based on the phase difference. In consideration of such a state, the propagation time T may be calculated as follows.

  First, the propagation time calculation unit calculates an inter-vehicle distance a between the host vehicle and the preceding vehicle. The inter-vehicle distance a may be calculated based on the position information of the own vehicle and the position information of the preceding vehicle sent from the preceding vehicle by inter-vehicle communication or the like. The position information is detected by the GPS 42 mounted on the host vehicle or the vehicle ahead. The preceding vehicle that is the calculation target of the inter-vehicle distance a may be determined in the same manner as when the calculation target of the average speed Vave is determined, for example.

  Based on the inter-vehicle distance a, the propagation time calculation unit calculates the number of other vehicles existing between the preceding vehicle and the host vehicle. This number is the number obtained by dividing the inter-vehicle distance a by the average distance b occupied by one vehicle (a ÷ b). The average distance b occupied by one vehicle is, for example, a length obtained by adding the total length per vehicle to the inter-vehicle distance between two consecutive vehicles. The inter-vehicle distance may be changed depending on the speed of the platoon (for example, substitute for the speed of the own vehicle). In addition, for example, a general passenger car and a large transport vehicle such as a large truck have different overall lengths. Therefore, when the type of the vehicle can be discriminated, the total length for each type may be calculated. The vehicle type is, for example, type information of a preceding vehicle sent by inter-vehicle communication, imaging information of an imaging device (not shown) that images the front of the host vehicle, and an imaging device on the road sent by road-to-vehicle communication. What is necessary is just to judge from the imaging information. Note that the number of other vehicles may be obtained by using imaging information of an imaging device on the road.

  Subsequently, the propagation time calculation unit obtains the propagation time T by multiplying the number of other vehicles (a ÷ b) by the average propagation time c per vehicle (a ÷ b × c). The average propagation time c per vehicle is an average value of the propagation time until the influence of the speed change of the vehicle is propagated to other vehicles behind the vehicle. The propagation time c may be changed by the speed of the formation (for example, the speed of the own vehicle is substituted).

  Hereinafter, the calculation processing operation of this driving support apparatus and driving support method will be described based on the flowchart of FIG.

  The driving assistance ECU 1 determines whether or not the execution of driving assistance is instructed (step ST5). In step ST5, for example, if the support switch 51 in the passenger compartment is ON, it is determined that the execution of driving support is instructed.

  The driving support ECU 1 ends this calculation process once if the execution of the driving support is not instructed, and acquires information necessary for the driving support if the execution of the driving support is instructed (step ST10). The necessary information is vehicle information of a preceding vehicle obtained by inter-vehicle communication or the like, and vehicle information such as the speed and position of the own vehicle.

  In the driving assistance ECU 1, the propagation time calculation unit obtains the propagation time T as described above (step ST15), and the averaging time calculation unit obtains an average time Tave obtained by doubling the propagation time T (step ST20).

  The average speed calculation unit of the driving assistance ECU 1 calculates the average speed Vave of the preceding vehicle (step ST25). This average velocity Vave may be calculated using the averaging time Tave and the above equation 2, or may be calculated using the propagation time T and the above equation 3. In the case of performing the calculation according to the latter expression 3, it is not always necessary to perform the calculation process of the averaging time Tave in step ST20.

  The target speed calculation unit of the driving assistance ECU 1 determines the average speed Vave of the preceding vehicle as the target speed Vtgt of the own vehicle (step ST30).

  In the driving assistance ECU 1, the braking / driving force control unit calculates the target driving force and the target braking force of the own vehicle based on the target speed Vtgt of the own vehicle, and executes the braking / driving force control according to the target speed Vtgt (step). ST35). As a result, the host vehicle travels behind the preceding vehicle at the target speed Vtgt, and can travel with less acceleration / deceleration than the preceding vehicle.

  Here, FIG. 5 shows the result of comparison between the speed of the own vehicle (target speed Vtgt) and the speed of the preceding vehicle when the braking / driving force control is performed, and the inter-vehicle distance between the own vehicle and the preceding vehicle. Show. As is apparent from this figure, the speed of the preceding vehicle is averaged with an averaging time Tave that is twice the propagation time T, and the average speed Vave of the preceding vehicle is set as the target speed Vtgt of the own vehicle. The phase of the speed of the host vehicle (target speed Vtgt) matches the phase of the speed of the preceding vehicle. This makes it possible for the vehicle to travel in a convoy that prevents the distance between the vehicle and the preceding vehicle from being excessively open or clogged, as compared to the conventional case where the speed of the preceding vehicle is averaged. In addition, it is possible to travel with less acceleration / deceleration in a row with reduced speed fluctuations.

  FIG. 6 shows the result of comparing the speed of the preceding vehicle to be averaged at this time, the average speed Vave of the preceding vehicle, and the speed of the preceding vehicle. Since the average speed Vave of the preceding vehicle corresponds to the target speed Vtgt of the own vehicle, it can be said that this figure is an enlarged part of the speed portion of FIG. As is clear from this figure, the phase of the average speed Vave of the vehicle ahead (the target speed Vtgt of the host vehicle) matches the phase of the speed of the preceding vehicle.

  7 and 8 are diagrams for comparison with the results of FIG. 9 and 10 are diagrams for comparison with the results of FIG.

  FIG. 7 shows the result when the speed of the preceding vehicle is averaged with the averaging time Tave obtained by multiplying the propagation time T by four times, and the average speed Vave of the preceding vehicle is set as the target speed Vtgt of the own vehicle. The result of comparison of the speed of the own vehicle (target speed Vtgt) and the speed of the preceding vehicle, and the inter-vehicle distance between the own vehicle and the preceding vehicle are shown. FIG. 9 shows the speed of the preceding vehicle to be averaged at this time, the average speed Vave of the preceding vehicle (the target speed Vtgt of the host vehicle), and the speed of the preceding vehicle. At this time, since the averaging time Tave is doubled compared with the result of FIG. 5, the amplitude of the average speed Vave of the preceding vehicle (target speed Vtgt of the own vehicle) can be further reduced, Further suppression of vehicle speed fluctuations becomes possible. However, at this time, since the phase of the average speed Vave of the preceding vehicle (target speed Vtgt of the own vehicle) and the phase of the preceding vehicle do not match, the distance between the own vehicle and the preceding vehicle is greatly increased.

  On the other hand, FIG. 8 shows the result when the speed of the preceding vehicle is averaged with the propagation time T as it is, and the average speed Vave of the preceding vehicle is set as the target speed Vtgt of the own vehicle. The result of comparison of the speed of the own vehicle (target speed Vtgt) and the speed of the preceding vehicle, and the inter-vehicle distance between the own vehicle and the preceding vehicle are shown. FIG. 10 shows the speed of the preceding vehicle to be averaged at this time, the average speed Vave of the preceding vehicle (target speed Vtgt of the host vehicle), and the speed of the preceding vehicle. At this time, since the averaging time Tave is halved compared to the result of FIG. 5, the amplitude of the average speed Vave of the preceding vehicle (target speed Vtgt of the own vehicle) cannot be suppressed, and further the preceding vehicle The phase of the average speed Vave (target speed Vtgt of the host vehicle) and the speed of the preceding vehicle are not matched. Therefore, at this time, the speed fluctuation of the own vehicle becomes large, and the distance between the own vehicle and the preceding vehicle is greatly increased.

  As described above, this driving support apparatus and driving support method averages the speed of the preceding vehicle with the averaging time Tave that doubles the propagation time T, and sets the average speed Vave of the preceding vehicle to that of the own vehicle. By setting the target speed Vtgt, it is possible to perform traveling with reduced speed fluctuations while maintaining the inter-vehicle distance from the preceding vehicle that does not feel uncomfortable in the formation. And this driving assistance device and driving assistance method are realizable about such an effect, even if the own vehicle can receive even one vehicle information in a plurality of front vehicles.

[Modification 1]
By the way, this driving support apparatus and driving support method averages the speed of the preceding vehicle with the averaging time Tave that is twice the propagation time T, so that the average speed Vave of the preceding vehicle (the target speed Vtgt of the host vehicle). ) Can be brought close to the phase of the speed of the own vehicle, and as a result, the phase of the target speed Vtgt of the own vehicle can be brought close to the phase of the speed of the preceding vehicle, but the respective phases can always be matched. Not necessarily. For this reason, in this driving support device and driving support method, for example, the speed fluctuation of the own vehicle is so large that the phase of the average speed Vave (target speed Vtgt of the own vehicle) cannot approach the phase of the own vehicle speed. There is a possibility that the degree of suppression will be low, or that the distance between the vehicle and the preceding vehicle will increase. Further, in this driving support device and driving support method, the phase of the average speed Vave of the preceding vehicle (target speed Vtgt of the host vehicle) may be advanced from the phase of the speed of the host vehicle. Therefore, in the present modification, when there is a difference between the phase of the average speed Vave of the vehicle ahead (the target speed Vtgt of the host vehicle) and the phase of the host vehicle speed, the respective phases are made as close as possible. More preferably, the averaging time Tave is corrected so that the respective phases coincide with each other.

  Specifically, a reference value of the averaging time Tave obtained by doubling the propagation time T is used, and the average speed Vave (target speed Vtgt of the own vehicle) averaged by this reference value and the speed of the own vehicle The averaging time Tave is corrected at a time T0 corresponding to the phase difference (Tave ← Tave + T0).

  For example, the arithmetic processing of this modification will be described based on the flowchart of FIG. Steps ST5 to ST25 and steps ST30 to ST35 are the same as steps ST5 to ST25 and steps ST30 to ST35 of FIG. 4 described above. Therefore, description of these arithmetic processing steps is basically omitted.

  After the average speed Vave of the preceding vehicle is calculated in step ST25, the averaging time calculation unit determines whether or not there is a phase difference between the average speed Vave and the speed of the host vehicle (step ST26).

  When there is no phase difference, the target speed calculation unit proceeds to step ST30 and determines the average speed Vave of the preceding vehicle as the target speed Vtgt of the own vehicle as in the above-described embodiment.

  On the other hand, if there is a phase difference, the averaging time calculation unit adds the time T0 corresponding to the phase difference to the reference value of the averaging time Tave that is twice the propagation time T, and corrects the averaging time Tave. It performs (step ST27). Here, if the phase of the speed of the host vehicle is behind the phase of the average speed Vave of the preceding vehicle, the time T0 corresponding to the phase difference is set to a negative value, and the averaging time Tave is shorter than the reference value. To do. On the other hand, when the phase of the speed of the host vehicle is ahead of the phase of the average speed Vave of the preceding vehicle, the time T0 corresponding to the phase difference is set to a positive value, and the averaging time Tave than the reference value. Lengthen.

  After the correction of the averaging time Tave, the process returns to step ST25, and the average speed calculation unit obtains the average speed Vave of the preceding vehicle again using the corrected averaging time Tave.

  In this example, the averaging time Tave is increased until there is no phase difference between the average speed Vave of the preceding vehicle and the speed of the host vehicle, or until this phase difference is equal to or smaller than a predetermined value (phase difference is substantially 0). The correction and the recalculation of the average speed Vave of the preceding vehicle are repeated. Then, the finally determined average speed Vave of the preceding vehicle is determined as the target speed Vtgt of the own vehicle.

  As described above, the driving support device and the driving support method of this modified example can not only obtain the same effect as the above-described embodiment, but also feel more uncomfortable in the formation than the embodiment. It is possible to perform traveling with less acceleration / deceleration in a platoon in which the speed fluctuation is further suppressed while maintaining a distance between the vehicle and the preceding vehicle.

  In this example, when the averaging time Tave is corrected, a time T0 corresponding to the phase difference is added. However, the correction changes the multiple of the propagation time T when the averaging time Tave is obtained (as opposed to 2). It may be performed by increasing or decreasing).

[Modification 2]
The driving support apparatus and driving support method according to the above-described embodiment and modification 1 are rather effective in a platoon around the own vehicle (for example, within a communicable range such as inter-vehicle communication). In the case of a long row of tens and hundreds, the accumulation of speed fluctuations of the respective front vehicles increases, so that the speed fluctuations of the target speed Vtgt of the own vehicle (average speed Vave of the front vehicles) in the rear vehicles. May remain as a long cycle (FIG. 12). FIG. 12 shows that the host vehicle is the 100th vehicle counting from vehicles capable of executing the same driving support as the host vehicle, for example, and the target vehicle Vtgt of the vehicle ahead is subject to calculation of the target speed Vtgt of the host vehicle several vehicles ahead of the host vehicle. It is the figure which showed the average speed Vave (target speed Vtgt of the own vehicle) and the inter-vehicle distance between the own vehicle and the preceding vehicle calculated by the reference value of the speed and the averaging time Tave. Circled portions (a, b, c) in this figure indicate places where the speed fluctuation of the average speed Vave of the preceding vehicle (target speed Vtgt of the own vehicle) is large. In addition, 50% of vehicles capable of executing the same driving support as the own vehicle are mixed between the own vehicle and the preceding vehicle 100 vehicles ahead of the own vehicle, and the same driving as the own vehicle is performed in each vehicle. Support is being implemented.

  In this driving support device and driving support method, in order to reduce the speed fluctuation, the averaging time Tave may be increased as shown in FIG. 7, but if the averaging time Tave is increased unnecessarily, The inconvenience arises that the inter-vehicle distance is greatly increased. Therefore, the driving support apparatus and driving support method according to the present modified example are averaged in the embodiment or the modified example 1 as long as the speed fluctuation ΔVa of the preceding vehicle that is the target of calculation of the target speed Vtgt of the host vehicle is larger than the predetermined value Va. Set the time Tave. On the other hand, this driving support device and driving support method uses the averaging time Tave in the embodiment or the modified example 1 as long as the speed fluctuation ΔVa of the preceding vehicle that is the target of calculation of the target speed Vtgt of the host vehicle is within the predetermined value Va. It is corrected and set longer than the averaging time Tave. In the latter, the predetermined time T1 is added to the averaging time Tave calculated by the vehicle ahead in its own driving support control, and this added time is set as the average time Tave of the own vehicle.

  For example, the arithmetic processing of this modification will be described based on the flowchart of FIG. Here, it is assumed that the nth vehicle from the top vehicle of the long platoon and the nkth vehicle from the top vehicle are the front vehicles from which the target speed Vtgt of the vehicle is to be calculated (FIG. 14).

  The driving assistance ECU 1 determines whether or not the execution of driving assistance is instructed (step ST51), as in step ST5 described above.

  The driving support ECU 1 ends this calculation process once if the execution of the driving support is not instructed, and acquires information necessary for the driving support if the execution of the driving support is instructed (step ST52). The necessary information is the vehicle information of the own vehicle (n) and the preceding vehicle (nk) that are the same as those in step ST10 described above. However, in this step ST52, not only the speed V (nk) of the preceding vehicle (nk) but also information on the averaging time Tave (nk) of the preceding vehicle (nk) is received. Yes. In step ST52, information on a predetermined time T1 (nk) of the preceding vehicle (nk) is also received. The predetermined time T1 (nk) transmitted by the preceding vehicle (nk) is the forward vehicle (n) for which the target speed Vtgt (nk) is calculated in the driving support control of the preceding vehicle (nk). When -m) does not exist (k <m), “NAN” is assumed.

  The driving assistance ECU 1 determines whether or not “T1 (n−k) = NAN” has been received (step ST53).

  In the case of receiving “T1 (n−k) = NAN”, the driving assistance ECU 1 determines the propagation time T in the same way as the above-described step ST15 (step ST54), and the averaging time calculation unit described above. Similar to step ST20, the average time Tave (n) of the own vehicle (n) in which the propagation time T is doubled is obtained (step ST55).

  On the other hand, the averaging time calculation unit of the driving assistance ECU 1 when not receiving “T1 (nk) = NAN” calculates the speed fluctuation ΔVa of the preceding vehicle (nk) (step ST56). The speed fluctuation ΔVa is, for example, the difference between the maximum value and the minimum value of the speed V (nk) of the preceding vehicle (nk) in a certain fixed period (several seconds, tens of seconds, etc.).

  This averaging time calculation unit determines whether or not the speed fluctuation ΔVa is larger than a predetermined value Va (step ST57). By using the averaging time Tave (n) of the embodiment or the modified example 1, the fluctuation of the target speed Vtgt (n) of the host vehicle (n) may be too large. The predetermined value Va may be set as follows, for example. First of all, a congested platoon has a certain percentage of the same driving support as that of the own vehicle for a plurality of vehicles (including the leading vehicle that fluctuates in speed) that cannot execute the same driving support as that of the own vehicle (n). It is assumed that this vehicle is mixed. The predetermined value Va may be determined with reference to the speed fluctuation range (results of experiments and simulations) within a certain time period (for example, within 20 seconds, etc.) of, for example, 20 rear vehicles in the formation. This is because the speed fluctuation range within a certain time is significantly smaller than that of the leading vehicle if there are about 20 vehicles behind. In the vehicle showing the speed variation ΔVa within the predetermined value Va set in this way and the vehicle behind the vehicle, the speed variation ΔVa of the preceding vehicle is small even if the averaging time Tave (n) is long. The inter-vehicle distance is not unnecessarily long, and a speed fluctuation (FIG. 12) with a long cycle in the rear vehicle can be eliminated as shown in FIG.

  If the speed variation ΔVa is larger than the predetermined value Va, the averaging time calculation unit proceeds to steps ST54 and ST55, and the averaging time Tave of the vehicle (n) in which the propagation time T and the propagation time T are doubled. (N) is obtained.

  On the other hand, if the speed fluctuation ΔVa is within the predetermined value Va, the averaging time calculating unit sets the predetermined time T1 of the own vehicle (n) to the averaging time Tave (nk) of the preceding vehicle (nk). (N) is added to determine the average time Tave (n) of the vehicle (n) (step ST58). It is desirable that the predetermined time T1 (n) be larger as the platoon including the vehicle having the driving support device according to the present invention is longer. For example, if the preceding vehicle (nk) has transmitted a predetermined time T1 (nk), the predetermined time T1 (n) is obtained by adding the time t0 (n) to the predetermined time T1 (nk). It may be assumed that {T1 (n) = T1 (n−k) + t0 (n)}. The time t0 (n) may be t0 as a fixed value. Further, since the own vehicle (n) is traveling k backwards as viewed from the preceding vehicle (nk), the time t0 (n) is t0 seconds per vehicle, and “t0 (n) = t0 × k ”may be set.

  The average speed calculation unit of the driving assistance ECU 1 calculates the average speed Vave (nk) of the preceding vehicle (nk), similarly to step ST25 described above (step ST59). This average speed Vave (n−k) is calculated using the averaging time Tave (n) in step ST55 or step ST58 and the above equation 2.

  The target speed calculation unit of the driving assistance ECU 1 determines the average speed Vave (nk) of the preceding vehicle (nk) as the target speed Vtgt (n) of the host vehicle (n) (step ST60).

  In the driving assistance ECU 1, the braking / driving force control unit calculates the target driving force and the target braking force of the host vehicle (n) based on the target speed Vtgt (n) of the host vehicle (n), and the target speed Vtgt (n). The braking / driving force control corresponding to is executed (step ST61). As a result, the host vehicle travels behind the preceding vehicle at the target speed Vtgt, and can travel with less acceleration / deceleration than the preceding vehicle.

  In the driving support device and the driving support method, when the averaging is performed with the averaging time Tave (n) in step ST55, the same operational effects as those of the above-described embodiment are obtained. In addition, although demonstrated based on the Example here, you may make it based on the modification 1, In this case, calculation of the average speed Vave (nk) of the front vehicle (nk) in step ST59 Later, Steps ST26 and ST27 of Modification 1 may be interposed.

  On the other hand, in this driving support device and driving support method, when averaged with the averaging time Tave (n) in step ST58, as shown in FIG. 15, the speed of the target speed Vtgt (n) of the host vehicle (n). Fluctuations can be reduced, and it is possible to run with less acceleration and deceleration in this formation.

[Modification 3]
In the driving support devices and driving support methods of the above-described embodiments and modifications 1 and 2, the propagation time T is calculated based on the speed of the own vehicle and the speed of the preceding vehicle. Further, in the driving support device and driving support method of this embodiment, the averaging time Tave is corrected based on the speed of the host vehicle and the average speed Vave of the preceding vehicle. However, for example, it is conceivable that the host vehicle has already traveled corresponding to the average speed Vave of the preceding vehicle. In this case, the calculation accuracy of the propagation time T and the correction accuracy of the averaging time Tave are reduced. There is a possibility. Therefore, when there is a possibility of causing such a decrease in accuracy, the speed of the preceding vehicle is substituted for the speed of the own vehicle (for example, the solid line in FIGS. 2 and 3 becomes the speed of the preceding vehicle), and the calculation of the propagation time T is performed. Alternatively, the averaging time Tave may be corrected. This is because the host vehicle and the preceding vehicle in the formation are more likely to exhibit the same acceleration / deceleration behavior than the preceding vehicle ahead of the preceding vehicle. Even with this configuration, the driving support apparatus and the driving support method can obtain the same effects as the above-described embodiment. In this case, “the speed of the own vehicle” is read as “the speed of the preceding vehicle”.

  For the speed of the preceding vehicle, information received by inter-vehicle communication or the like may be used, or a calculated value based on the inter-vehicle distance detected by the distance detection device 52 of the own vehicle may be used.

  The distance detection device 52 is a distance sensor for detecting an actual relative distance between the host vehicle and the preceding vehicle (hereinafter referred to as “actual relative distance”). As the distance detection device 52, for example, a millimeter wave radar may be used. This millimeter wave radar is attached to, for example, the center of the front part of the vehicle (inside the front grill or the like). This millimeter wave radar emits a millimeter wave to a predetermined range in front of the host vehicle, and receives the millimeter wave reflected by an object existing in front of the host vehicle. This millimeter wave radar detects the actual relative distance by measuring the time from emission to reception and calculating the distance from the vehicle (millimeter wave radar placement site) to the object ahead. The distance detection device 52 may be a radar using laser or infrared rays, an imaging device such as a CCD (Charge Coupled Device) camera, or the like. For example, in this case, image processing of forward captured image data captured by the imaging device is performed, and the actual relative distance is calculated. The driving support ECU 1 calculates an actual relative speed (hereinafter referred to as “actual relative speed”) between the host vehicle and the preceding vehicle based on a change in the actual relative distance with time, and this actual relative speed. The speed of the preceding vehicle can be obtained from the speed and the speed of the own vehicle. In the millimeter wave radar, the actual relative speed can be detected by calculating the speed difference between the speed of the own vehicle and the speed of the preceding vehicle using the Doppler effect.

  By the way, in the driving assistance apparatus and driving assistance method of the said Example and the modifications 1-3, the speed of the front vehicle which drive | works ahead of a preceding vehicle is averaged, and the average speed is made into the target speed of the own vehicle. Yes. However, for example, when the vehicle is running near the top of the platoon or when the other vehicle is not equipped with a driving support device, the vehicle will display speed information on the vehicle ahead (except for the preceding vehicle). There is a case where it cannot be obtained. In this case, the driving support device for the own vehicle performs inter-vehicle distance control with the preceding vehicle by so-called ACC (Adaptive Cruise Control). In this case, this driving support device may use the speed information of the preceding vehicle if it can be obtained by inter-vehicle communication or the like. 52 may be used. In this driving support device and driving support method, when the speed information of the preceding vehicle (excluding the preceding vehicle) cannot be acquired, the inter-vehicle distance control by the ACC is described in the embodiments and the first to third modifications. The same control (running with the average speed of the preceding vehicle as the target speed of the host vehicle) may be executed.

1 Driving assistance ECU
2 Travel control ECU
DESCRIPTION OF SYMBOLS 11 Power source 21 Brake part 22 Brake hydraulic pressure control part 41 Communication apparatus 51 Support switch 52 Distance detection apparatus 100 Vehicle

Claims (6)

A propagation time calculation unit for calculating the propagation time until the influence of the speed change of the forward vehicle traveling in front of the own vehicle is propagated to the own vehicle or the preceding vehicle traveling immediately before the own vehicle;
An averaging time calculation unit that sets an averaging time used for calculating an average speed of the preceding vehicle to be twice the propagation time;
An average speed calculator that calculates an average speed of the preceding vehicle using the averaging time;
A target speed calculator for calculating the target speed of the vehicle based on the average speed;
A braking / driving force control unit that performs braking / driving force control with a target driving force and a target braking force of the vehicle according to the target speed;
A driving support apparatus comprising:   If there is a phase difference between the speed of the own vehicle or the speed of the preceding vehicle and the average speed of the preceding vehicle, the averaging time calculation unit may reduce the phase difference or eliminate the phase difference. The driving support device according to claim 1, wherein the driving time is corrected.   3. The driving support device according to claim 1, wherein the averaging time calculation unit increases the averaging time as the number of front vehicles increases. Calculating the propagation time until the influence of the speed change of the forward vehicle traveling in front of the host vehicle is propagated to the host vehicle or the preceding vehicle traveling immediately before the host vehicle;
An averaging time used for calculating the average speed of the vehicle ahead is double the propagation time;
Calculating the average speed of the preceding vehicle using the averaging time;
Calculating a target speed of the vehicle based on the average speed;
Performing braking / driving force control with a target driving force and a target braking force of the vehicle according to the target speed;
A driving support method characterized by comprising:   When there is a phase difference between the speed of the own vehicle or the speed of the preceding vehicle and the average speed of the preceding vehicle, the step of correcting the averaging time so as to reduce the phase difference or eliminate the phase difference The driving support method according to claim 4, further comprising:   6. The driving support method according to claim 4, further comprising a step of increasing the averaging time as the number of front vehicles increases.

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