JP2019214225A - Operation support device - Google Patents

Abstract

To enhance traveling feeling concerning an operation support device at tracking to a preceding vehicle.SOLUTION: In an operation support device 1 which executes tracking control for adjusting driving force and braking force of an own vehicle 10 so that vehicle distance up to a preceding vehicle 20 agrees with target distance, there is provided an acquisition part 2, a calculation part 3 and a control part 4. The acquisition part 2 acquires vehicle speed V of the own vehicle 10, relative speed Vof the preceding vehicle 20 for the own vehicle 10, vehicle separation distance D, and absolute speed Vof the preceding vehicle 20. The calculation part 3 calculates an average value Vof the absolute speed Vin a prescribed duration. The control part 4 is in a speed range in which the relative speed Vcontains 0, and furthermore executes stationary speed control in stead of tracking control when the vehicle separation distance D is in a distance range containing the target distance. In the stationary speed control, the driving force and the braking force are adjusted so that the vehicle speed V agrees with the average value V.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a driving support device that performs cruise control.

  2. Description of the Related Art Conventionally, as one function of cruise control of a vehicle, a function of controlling the movement of a host vehicle so as to follow a preceding vehicle ahead is known. That is, a constant inter-vehicle distance is maintained by automatically adjusting the driving force and the braking force of the own vehicle according to the difference between the target inter-vehicle distance from the own vehicle to the preceding vehicle and the actual inter-vehicle distance. To run the vehicle. Such a follow-up function is suitable for traveling on, for example, a highway or an automobile-only road, and can reduce the burden of a driver's driving operation (see Patent Documents 1 and 2). In recent years, vehicles that perform control of following a preceding vehicle not only during high-speed running but also in a low-speed range (for example, 40 km / h or less) have been sold.

JP 2014-144744 A JP 2009-208735 A

  Since the following control described above is a control based on the inter-vehicle distance with the preceding vehicle, the behavior of the preceding vehicle is likely to be reflected in the movement of the own vehicle, and the running feeling of the own vehicle may be reduced. . For example, when the host vehicle is running slowly on a congested road, the preceding vehicle to be followed may suddenly move forward. In this case, since the inter-vehicle distance increases sharply, the driving force increases rapidly by the follow-up control, and the own vehicle starts suddenly. On the other hand, when the inter-vehicle distance to the preceding vehicle is shortened due to the sudden start, the braking force is rapidly increased by the following control, and the own vehicle is suddenly stopped. As a result, the movement of the host vehicle becomes jerky, and a good traveling feeling cannot be obtained. The same applies not only when the preceding vehicle suddenly starts or decelerates, but also when the preceding vehicle fluctuates, and the following control of the host vehicle reacts sensitively to minute acceleration fluctuations of the preceding vehicle. Sometimes it is too much. The decrease in running feeling is particularly remarkable in the following control in a low speed range, but may also occur in the following control in a high speed range.

  One of the objects of the present invention has been made in view of the above-described problem, and it is an object of the present invention to provide a driving support device that can improve a running feeling when following a preceding vehicle. It is to be noted that the present invention is not limited to this purpose, and is an operation effect derived from each configuration shown in “Embodiments for carrying out the invention” to be described later. Can be positioned as a purpose.

  (1) The disclosed driving assistance device is a driving assistance device that performs follow-up control for adjusting the driving force or the braking force of the own vehicle such that the inter-vehicle distance to the preceding vehicle becomes the target distance. The present device includes an acquisition unit that acquires the vehicle speed of the host vehicle, the relative speed of the preceding vehicle with respect to the host vehicle, the inter-vehicle distance, and the absolute speed of the preceding vehicle. Also, a calculation unit is provided for calculating an average value of the absolute speed within a predetermined period. Further, when the relative speed is within a predetermined speed range including 0 and the inter-vehicle distance is within a predetermined distance range including the target distance, the vehicle speed is reduced to the average speed instead of the following control. A control unit for performing a fixed speed control for adjusting the driving force or the braking force so as to have a value.

(2) It is preferable that the control section performs the following control when the relative speed is outside the predetermined speed range or when the inter-vehicle distance is outside the predetermined distance range.
(3) Preferably, the average value is a moving average value of the absolute speed within the predetermined period.

(4) It is preferable that the control unit performs the fixed speed control when the vehicle speed is lower than a predetermined vehicle speed.
(5) Preferably, the predetermined distance range is set so as to increase as the vehicle speed increases.
(6) It is preferable that the predetermined speed range is set so as to increase as the vehicle speed increases.

  When the relative speed is within the predetermined speed range and the inter-vehicle distance is within the predetermined distance range, the driving force and the braking force are adjusted so that the vehicle speed becomes the average value of the vehicle speed of the preceding vehicle. Therefore, it becomes easy to cause the vehicle to follow the preceding vehicle while alleviating a sudden change in the vehicle speed of the own vehicle due to acceleration and deceleration of the preceding vehicle. Therefore, the running state of the vehicle can be stabilized, and the running feeling when following the preceding vehicle can be improved.

FIG. 1 is a diagram illustrating a configuration of a vehicle to which a driving support device according to an embodiment is applied. It is a figure which shows the range of the inter-vehicle distance in which follow-up control and fixed speed control are implemented. It is a block diagram for explaining composition of a driving support device. 5 is a graph showing a relationship between a vehicle speed and a predetermined speed range. 5 is a graph showing a relationship between a vehicle speed and a predetermined distance range. 5 is a flowchart illustrating a flow of control performed by the driving support device. 4A and 4B are graphs for explaining the behavior of the own vehicle and the preceding vehicle, wherein FIG. 4A shows the temporal change of the absolute speed V _ACT of the preceding vehicle, and FIGS. 5B and 5C show the temporal change of the vehicle speed V of the own vehicle.

  Hereinafter, a driving support device 1 as an embodiment will be described with reference to the drawings. The embodiment described below is merely an example, and there is no intention of excluding various modifications and technical applications that are not explicitly described in the following embodiment. Each configuration of the present embodiment can be implemented with various modifications without departing from the spirit thereof. Further, they can be selected as necessary, or can be appropriately combined.

[1. Constitution]
The driving support device 1 (driving support ECU) of the present embodiment is applied to a vehicle 10 (hereinafter, also referred to as a host vehicle 10) illustrated in FIG. The driving support device 1 is an electronic control device (computer) having at least a function of automatically following the host vehicle 10 with the preceding vehicle 20. The driving support device 1 includes a processor (central processing unit), a memory (main memory), a storage device (storage), an interface device, and the like, and these are connected to each other via an internal bus. Preferably, the driving support device 1 is an electronic control device for adaptive cruise control (ACC) that performs a control of following the preceding vehicle 20 and a cruise control.

The follow-up control is control for adjusting the driving force and the braking force of the own vehicle 10 so that the inter-vehicle distance D from the own vehicle 10 to the preceding vehicle 20 becomes the target distance _DTGT . This control can be performed at least when the preceding vehicle 20 is ahead of the host vehicle 10. The target distance _DTGT in the follow-up control is set according to, for example, the vehicle speed V of the _host vehicle 10 or the relative speed _VREL of the preceding vehicle 20, or to a predetermined distance. In the present embodiment, the driving force and the braking force of the vehicle 10 during the follow-up control are feedback-controlled based on the difference between the actual inter-vehicle distance D and the target distance D _TGT .

The constant-speed running control is control for adjusting the driving force and the braking force of the own vehicle 10 so that the vehicle speed V becomes a constant target vehicle speed _VTGT when the preceding vehicle 20 is not in front of the own vehicle 10. . The target that is the control target in the following control is the inter-vehicle distance D, whereas the target that is the control target in the constant-speed running control is the vehicle speed V. The target vehicle speed V _TGT in the constant speed traveling control is set according to, for example, a speed input by a driver, a legal speed of a road, or the like, or to a predetermined speed. In the present embodiment, based on the difference between the actual vehicle speed V and the target vehicle speed _VTGT , the driving force and the braking force of the own vehicle 10 during the constant speed traveling control are feedback controlled.

In addition, in the driving support device 1 of the present embodiment, not only the following control and the constant speed traveling control, but also a fixed speed control is performed. The fixed speed control is a control that is performed instead of the following control when the preceding vehicle 20 is in front of the host vehicle 10 and the inter-vehicle distance D and the relative speed V _REL satisfy predetermined conditions. . In the fixed speed control, the driving force and the braking force of the host vehicle 10 are adjusted so that the host vehicle 10 runs at a stable speed while suppressing the change in the inter-vehicle distance D. The target to be controlled in the fixed speed control is the vehicle speed V as in the case of the constant speed traveling control. However, the target value of the vehicle speed V is not the target vehicle speed V _TGT but the average value V _AVE of the vehicle speed (absolute speed V _ACT ) of the preceding vehicle 20. Preferably, the target value of the vehicle speed V is fixed for a certain period of time.

  The start conditions of the following control, the constant speed traveling control, and the fixed speed control can be the same as those of the known adaptive cruise control. For example, any of the following control, the constant-speed running control, and the fixed-speed control may be started with the driver turning on an ACC switch (not shown) as a trigger. The additional start condition may be that the vehicle 10 is traveling on a highway or a motorway.

  As shown in FIG. 1, the vehicle 10 is equipped with an engine 11 (internal combustion engine) as a drive source and a transmission 12 for changing the rotation speed and torque of the driving force output from the engine 11. You. When the vehicle 10 is an electric vehicle, an electric motor is mounted instead of the engine 11. In the case of a hybrid vehicle, both the engine 11 and the electric motor can be the driving sources of the vehicle 10. The transmission 12 is, for example, a multi-stage transmission having a plurality of shift stages, or a continuously variable transmission capable of continuously changing a gear ratio. The transmission 12 is interposed on a power transmission path between the engine 11 and the drive wheels.

  Each wheel of the vehicle 10 is provided with a braking device 13 and a vehicle speed sensor 14. The braking device 13 controls the braking force of the host vehicle 10, and is, for example, a hydraulic brake device or an air brake device. The operation state of the braking device 13 is controlled by the driving support device 1. The vehicle speed sensor 14 outputs a pulse signal corresponding to the rotation speed of each axle to the driving support device 1. The traveling speed (vehicle speed V) of the host vehicle 10 can be calculated based on these pulse signals.

A radar device 15 is provided at a front end of the vehicle 10. The radar device 15 is a detector for detecting an inter-vehicle distance D to a preceding vehicle 20 existing in front of the host vehicle 10 and a relative speed _VREL . The radar device 15 has a function of radiating a transmission wave in front of the vehicle 10 and receiving the reflected wave. The inter-vehicle distance D to the preceding vehicle 20 that has reflected the reflected wave is determined based on the reflection time and phase difference of the reflected wave with respect to the transmitted wave. Further, the relative speed V _REL of the preceding vehicle 20 is determined from the change in the inter-vehicle distance D per unit time. Alternatively, the relative velocity V _REL is obtained from the Doppler shift of the signal frequency of the reflected wave. The direction of the preceding vehicle 20 is grasped from the transmission direction of the transmission wave and the reception direction of the reflected wave.

The radar device 15 of the present embodiment detects an inter-vehicle distance D to a preceding vehicle 20 traveling ahead in the same lane as the host vehicle 10 and a relative speed V _REL thereof. The definition of the relative speed _VREL is the traveling speed of the preceding vehicle 20 in a coordinate system fixed to the host vehicle 10. The relative speed V _REL corresponds to a value obtained by subtracting the vehicle speed V of the own vehicle 10 from the actual vehicle speed (speed with respect to the road surface, the absolute speed V _ACT ) of the preceding vehicle 20, and when the preceding vehicle 20 is moving away from the own vehicle 10. Is positive, and negative when the preceding vehicle 20 is approaching the host vehicle 10. The information on the inter-vehicle distance D and the relative speed V _REL obtained here is transmitted to the driving support device 1. Note that specific examples of the radar device 15 include a millimeter-wave radar, a microwave radar, a laser radar, an image sensor (camera), an ultrasonic sensor, and the like.

  The positioning device 16 is an electronic control device (for example, an electronic control device for measuring the position of the vehicle 10 based on detection information from a GNSS (Global Navigation Satellite System), a vehicle speed sensor, a steering angle sensor, a yaw rate sensor, and the like. Car navigation device). Here, the position information (latitude, longitude, and height information) of the vehicle 10 is measured with reference to the world geodetic system. In addition, information on the gradient of the road surface is also acquired based on the change in the position of the host vehicle 10. The information on the current position measured here is transmitted to the driving support device 1 as needed.

The communication device 17 is an electronic control device for exchanging information via a network (not shown) or using inter-vehicle communication with another vehicle. The communication device 17 has a function of obtaining map information (road map information) stored in a server on the network and a function of obtaining vehicle speed information of the preceding vehicle 20. By acquiring the map information, the current position, the traveling route, the target point, and the like of the host vehicle 10 can be accurately grasped. Also, by acquiring the vehicle speed information, the absolute speed V _ACT of the preceding vehicle 20 can be grasped with good estimation. In addition, each of the driving support device 1, the positioning device 16, and the communication device 17 may be provided as an independent electronic control device, or may be provided as an integrated electronic control device. A known configuration can be applied to a specific hardware configuration of the electronic control device.

  The accelerator sensor 18 is a sensor (for example, an accelerator position sensor) that detects an amount of depression of an accelerator pedal (accelerator opening). The brake sensor 19 is a sensor (for example, a brake stroke sensor or a brake fluid pressure sensor) that detects the amount of depression of a brake pedal or a brake fluid pressure corresponding to the amount of depression. The depression operation of the accelerator pedal or the brake pedal can be used as one of the conditions for terminating (or temporarily stopping) the following control, constant speed running control, and fixed speed control.

FIG. 2 is a diagram for explaining the relationship between the content of control performed by the driving support device 1 and the inter-vehicle distance D to the preceding vehicle 20. Controls that can be performed in a state where the preceding vehicle 20 is in front of the host vehicle 10 are tracking control and fixed speed control. The following control can be performed when the following distance D is less than the threshold A or when the following distance D exceeds the threshold B. In the former case (D <A), feedback control (control of braking force) for decelerating the own vehicle 10 is performed so that the inter-vehicle distance D becomes the target distance D _TGT . In the latter case (D> B), feedback control (control of driving force) for accelerating the vehicle 10 is performed so that the inter-vehicle distance D becomes the target distance D _TGT . Note that the target distance _DTGT in the following control is included in a range from the threshold A to the threshold B.

On the other hand, when the inter-vehicle distance D is equal to or larger than the threshold value A and equal to or smaller than the threshold value B (A ≦ D ≦ B), fixed speed control may be performed. In the fixed speed control, the driving force and the braking force of the own vehicle 10 are feedback-controlled so that the vehicle speed V becomes the average value V _AVE of the vehicle speed (absolute speed V _ACT ) of the preceding vehicle 20. The value of the average value V _AVE may be updated each time, or may be fixed for a certain period of time. In any case, the follow-up control functions to make the inter-vehicle distance D asymptotic to the target distance D _TGT , whereas the fixed speed control changes the vehicle speed V of the own vehicle 10 to the vehicle speed of the preceding vehicle 20 (absolute speed V _ACT ). It works to asymptotically approach the speed.

[2. Control configuration]
As shown in FIG. 3, a vehicle speed sensor 14, a radar device 15, a positioning device 16, a communication device 17, an accelerator sensor 18, and a brake sensor 19 are connected to an input side of the driving support device 1, and an engine 11 and a brake sensor 19 are connected to an output side. The transmission 12 and the braking device 13 are connected. Further, the driving support device 1 includes an acquisition unit 2, a calculation unit 3, and a control unit 4. These elements represent functional blocks for explaining the content of fixed speed control, among the three controls of follow-up control, constant speed operation control, and fixed speed control. Each element is described as an independent program. Alternatively, it may be described as a composite program having individual functions.

The acquisition unit 2 acquires the vehicle speed V of the own vehicle 10, the relative speed V _REL of the preceding vehicle 20 with respect to the own vehicle 10, the inter-vehicle distance D to the preceding vehicle 20, and the absolute speed V _ACT of the preceding vehicle 20. It is. Here, based on a plurality of pulse signals transmitted from the vehicle speed sensor 14, the vehicle speed V corresponding to the minimum value or the average value of the frequency is calculated. When the vehicle speed sensor 14 can calculate the value of the vehicle speed V, the value may be simply input to the acquisition unit 2.

Further, the acquisition unit 2 calculates the relative speed V _REL of the preceding vehicle 20 and the inter-vehicle distance D to the preceding vehicle 20 based on the transmission wave and the reflected wave of the radar device 15. When the radar device 15 itself can calculate the values of the relative speed V _REL and the inter-vehicle distance D, it is only necessary to input those values to the acquisition unit 2. If the radar device 15 can detect the ground speed of the vehicle 10, the vehicle speed V may be obtained based on information obtained by the radar device 15 instead of the vehicle speed sensor 14. Alternatively, the vehicle speed V may be obtained based on a change in the position of the host vehicle 10 measured by the positioning device 16.

Further, the acquisition unit 2 acquires the absolute speed V _ACT of the preceding vehicle 20 based on the vehicle speed V and the relative speed V _REL . Here, the sum of the vehicle speed V and the relative speed V _REL is calculated as the absolute speed V _ACT of the preceding vehicle 20. Note that the communication device 17 performs inter-vehicle communication between the own vehicle 10 and the preceding vehicle 20 to directly obtain information on the vehicle speed (absolute speed V _ACT ) of the preceding vehicle 20 from the preceding vehicle 20 itself. It may be. The information on the absolute speed V _ACT obtained here is transmitted to the calculation unit 3.

The calculator 3 calculates an average value V _AVE of the absolute speed V _ACT within a predetermined period. Here, for example, all the values of the absolute speed V _ACT acquired in the past 30 seconds are stored. Further, a moving average value in the past 15 seconds is calculated as an average value _VAVE . Alternatively, the upper limit value and the lower limit value of the absolute speed V _ACT in the past 30 seconds are extracted, and the arithmetic average of them is calculated as the average value V _AVE . The length of the predetermined period is set, for example, from several seconds to several minutes in accordance with the memory capacity of the driving support device 1. Note that the length of the predetermined time may be a variable length according to the traveling state of the vehicle 10. As the predetermined time is shortened, the change in the absolute speed V _ACT of the preceding vehicle 20 is immediately reflected in the average value V _AVE , and the followability of the host vehicle 10 to the preceding vehicle 20 is improved. On the other hand, as the predetermined time becomes longer, the change in the absolute speed V _ACT of the preceding vehicle 20 is less likely to be reflected on the average value V _AVE, and the stability of the vehicle speed V of the host vehicle 10 is improved.

The control unit 4 performs at least tracking control and fixed speed control. Here, when a predetermined start condition is satisfied in a state where the preceding vehicle 20 is in front of the host vehicle 10 (for example, when the ACC switch is turned on), either the fixed speed control or the follow-up control is performed. You. The execution condition of the fixed speed control is that at least the following conditions 1 and 2 are both satisfied. On the other hand, the execution condition of the follow-up control is that at least one of the conditions 1 and 2 is not satisfied.
Condition 1. 1. The relative speed V _REL is within a predetermined speed range. 2. The inter-vehicle distance D is within a predetermined distance range. The vehicle speed V is lower than the predetermined vehicle speed V ₀

  In this embodiment, when the condition 3 is satisfied in addition to the conditions 1 and 2, the fixed speed control is performed. If any of the conditions 1 to 3 is not satisfied, the follow-up control is performed. Either the fixed speed control or the following control is exclusively performed. That is, when the fixed speed control is performed, the tracking control is not performed, and when the tracking control is performed, the fixed speed control is not performed. Examples of control start conditions are shown below.

The “predetermined speed range” in the condition 1 is a range including at least 0, and is set so as to straddle both the negative speed region and the positive speed region. The “predetermined speed range” may be a fixed range that is set in advance, or may be a variable range that is set according to the traveling state of the vehicle 10. For example, the setting may be such that the predetermined speed range is expanded as the vehicle speed V of the host vehicle 10 increases. Here, if the lower limit value of the speed range is a threshold value X and the upper limit value of the speed range is a threshold value Y, X ≦ _VREL ≦ Y (the relative speed _VREL falls within the speed range from the threshold value X to the threshold value Y). Is satisfied), the condition 1 is satisfied.

Also, as shown in FIG. 4, the threshold value X may be decreased in a negative range as the vehicle speed V increases, and the threshold value Y may be increased in a positive range as the vehicle speed V increases. In this case, the maximum value _{XMAX of the} threshold value X and the minimum value _YMIN of the threshold value Y may be set so that the predetermined speed range does not become excessively narrow when the vehicle speed V is low. As a result, it is easy to secure the width of the speed range, and it is possible to easily satisfy the condition 1 even when the vehicle speed V is low.

An example of a specific value (absolute value) of the thresholds X and Y is about several km / h (for example, 1 to 5 km / h). The threshold value X functions as a parameter that determines the ease with which fixed speed control is performed when the preceding vehicle 20 is approaching. The threshold value Y functions as a parameter that determines the ease with which the fixed speed control is performed when the preceding vehicle 20 is moving away from the vehicle. Therefore, when it is desired to change the ease of performing the fixed speed control depending on the traveling state of the preceding vehicle 20, these absolute values may be set to different values. Incidentally, the constant-speed control in the present embodiment is implemented, the vehicle speed V is restricted when less than the predetermined vehicle speed V ₀ (when the condition 3 is satisfied). Therefore, among the graph shown in FIG. 4, right part than the predetermined vehicle speed V ₀ may be omitted.

  The same applies to the “predetermined distance range” in the condition 2, which may be a fixed range that is set in advance or a variable range that is set according to the traveling state of the vehicle 10. . For example, as shown in FIG. 5, the setting may be such that the predetermined distance range is expanded as the vehicle speed V of the host vehicle 10 increases. By expanding the operation range in which the fixed speed control is performed, the running stability of the vehicle 10 is further improved. Here, assuming that the lower limit of the distance range is the threshold A and the upper limit of the distance range is the threshold B, A ≦ D ≦ B (the inter-vehicle distance D is within the distance range from the threshold A to the threshold B). Condition 2) is satisfied.

This distance range includes at least the target distance D _TGT at the time of tracking control. Therefore, threshold value A is set to a value smaller than target distance D _{TGT at} that time, and threshold value B is set to a value larger than target distance D _TGT at that time. Further, the minimum values A _MIN and B _MIN of the thresholds A and B may be set so that the predetermined distance range does not become too narrow when the vehicle speed V is low. As a result, the width of the distance range can be easily secured, and the condition 2 can be easily satisfied even when the vehicle speed V is low. A specific example of the threshold A may be several meters or more (for example, 5 to 10 m), and a specific example of the threshold B may be about ten and several meters (for example, 30 to 50 m). Among the graph shown in FIG. 5, the right side portion than the predetermined vehicle speed V ₀ may be omitted.

As described above, the jerky movement of the own vehicle 10 due to the following control becomes remarkable especially in a low speed range. For this reason, it is preferable that the predetermined vehicle speed V ₀ in the condition 3 be set to a value that facilitates the establishment of the condition 3 when traveling in a low speed range. Specific examples of the predetermined vehicle speed V _0, it is conceivable to several km / h or more (e.g., 5 ~ 10km / h). As a result, it is possible to perform the fixed speed control in a low speed range where the movement of the host vehicle 10 is likely to be jerky, and to perform the following control instead of the fixed speed control in the middle speed range or the high speed range. It becomes possible.

[3. flowchart]
FIG. 6 is a flowchart for explaining the control content regarding the selection between the fixed speed control and the following control in the adaptive cruise control. This flow is repeatedly performed at a predetermined cycle when either the fixed speed control or the follow-up control is being performed.
In step A1, the acquisition unit 2 acquires information on the vehicle speed V, the inter-vehicle distance D, and the relative speed V _REL of the preceding vehicle 20 of the own vehicle 10. In step A2, the absolute speed V _ACT of the preceding vehicle 20 is calculated based on the vehicle speed V and the relative speed V _REL . Alternatively, information on the absolute speed V _ACT is obtained by inter-vehicle communication with the preceding vehicle 20.

In step A3, a predetermined distance range and a predetermined speed range are calculated based on the vehicle speed V. These ranges can be calculated based on maps such as those shown in FIGS. In the following step A4, the calculating unit 3 calculates an average value V _AVE of the absolute speed V _ACT within a predetermined period. The average value V _AVE may be a moving average value of the absolute speed V _ACT or an arithmetic average value of an upper limit value and a lower limit value.

Steps A5 to A7 are steps for judging the success or failure of the above conditions 1 to 3. In step A5, it is determined whether or not the relative speed V _REL is within a predetermined speed range (condition 1). In step A6, it is determined whether or not the inter-vehicle distance D is within a predetermined distance range (condition 2). You. The step A7, the vehicle speed V is equal to or less than a predetermined vehicle speed V ₀ (Condition 3) is determined. When all of steps A5 to A7 are satisfied, the process proceeds to step A8, and fixed speed control is performed. In this case, the driving force and the braking force of the vehicle 10 are feedback-controlled so that the vehicle speed V becomes the average value _VAVE (step A9). On the other hand, when any of the conditions of steps A5 to A7 is not satisfied, the process proceeds to step A10, and the following control is performed. In this case, the driving force and the braking force of the own vehicle 10 are feedback-controlled so that the inter-vehicle distance D becomes the target distance D _TGT (step A11).

[4. Action / Effect]
It is assumed that the absolute speed V _ACT of the preceding vehicle 20 changes as shown in FIG. 7A when the host vehicle 10 is performing follow-up control for the preceding vehicle 20. In the following control, the vehicle speed V of the host vehicle 10 is controlled such that the inter-vehicle distance D becomes the target distance D _TGT . Therefore, as shown by a broken line in FIG. 7B, the variation graph of the vehicle speed V of the host vehicle 10 has the same shape as the preceding vehicle 20 and changes slightly later than the preceding vehicle 20.

On the other hand, in the fixed speed control, the control target is changed from the inter-vehicle distance D to the vehicle speed V, and the driving force of the host vehicle 10 is _adjusted so that the vehicle speed V becomes the average value V _AVE of the absolute speed V _ACT . The braking force is feedback controlled. The value of the average value V _{AVE is} a value obtained by equalizing the absolute speed V _ACT of the preceding vehicle 20 within a predetermined period. For example, the vehicle speed V ₁ of the vehicle 10 at time t ₁ in FIG. 7 (B) the absolute velocity within a predetermined time period immediately before time t ₁ [FIG 7 (A) time t ₀ ~t ₁ in] V _It is close to the average value V _{AVE of ACT} . By such control, a change in the vehicle speed V of the host vehicle 10 is suppressed as indicated by a solid line in FIG. 7B. On the other hand, since the change in the absolute speed V _ACT of the preceding vehicle 20 is reflected in the average value V _AVE , it is also possible to prevent the inter-vehicle distance D from becoming extremely wide or from being too close to the preceding vehicle 20.

(1) The necessary conditions for the above fixed speed control are condition 1 and condition 2. Condition 1 is "the relative speed V _REL is within a predetermined speed range", and Condition 2 is "the inter-vehicle distance D is within a predetermined distance range". When both of these conditions are satisfied, the fixed speed control is performed instead of the follow-up control, whereby the sudden change in the vehicle speed of the host vehicle 10 due to the acceleration / deceleration of the preceding vehicle 20 is reduced, and the host vehicle 10 is moved to the preceding vehicle 20. , And the running state can be stabilized. Therefore, the running feeling at the time of following the preceding vehicle 20 can be improved.

(2) When the condition 1 is not satisfied or the condition 2 is not satisfied, the fixed speed control is not performed and the follow-up control is performed. Accordingly, when the inter-vehicle distance D from the preceding vehicle 20 is excessively far from the target distance D _TGT or when the inter-vehicle distance D is likely to change suddenly, the inter-vehicle distance D can be appropriately adjusted by the follow-up control. Therefore, the running feeling at the time of following the preceding vehicle 20 can be improved.

(3) In the driving support device 1 described above, the moving average value (average value V _AVE ) of the absolute speed V _ACT within a predetermined period (for example, 15 seconds) is calculated, and the vehicle speed V under fixed speed control is calculated as the average value V _AVE. The driving force and the braking force are adjusted so that As described above, by performing the fixed speed control using the moving average value of the absolute speed V _ACT , the influence of the vehicle speed fluctuation of the preceding vehicle 20 can be equalized. Therefore, the variation in the inter-vehicle distance D can be suppressed, and the ability to follow the preceding vehicle 20 can be improved.

(4) In the driving support device 1 described above, when the condition 3 is satisfied in addition to the conditions 1 and 2, the fixed speed control is performed. Condition 3 is that “the vehicle speed V is lower than the predetermined vehicle speed V ₀ ”. As described above, by including the condition 3 in the necessary condition of the fixed speed control, the jerky movement (jerky feeling) of the host vehicle 10 in the low speed region can be efficiently reduced, and the running state can be stabilized. it can. Further, in the middle speed range or the high speed range, the follow-up control is performed instead of the fixed speed control, so that the following distance D can be easily maintained at the target distance D _TGT .

  (5) In the driving support device 1 described above, as shown in FIG. 5, it is possible to set so that the predetermined distance range is expanded as the vehicle speed V increases. With such a setting, the driving range in which the fixed speed control is performed can be expanded, and the traveling stability of the vehicle 10 can be further improved.

  (6) Similarly, as shown in FIG. 4, it is also possible to set such that the predetermined speed range increases as the vehicle speed V increases. Even in such a setting, the operating range in which the fixed speed control is performed can be expanded, and the traveling stability of the vehicle 10 can be further improved. Note that the inter-vehicle distance D required to secure a constant inter-vehicle time increases as the vehicle speed V increases. On the other hand, by increasing the thresholds A and B as the vehicle speed V increases, the inter-vehicle time can be easily secured, and the traveling stability of the host vehicle 10 can be further improved.

[5. Modification]
The above embodiment is merely an example, and there is no intention to exclude various modifications and application of technology not explicitly described in the present embodiment. Each configuration of the present embodiment can be variously modified and implemented without departing from the spirit thereof. Further, they can be selected as needed, or can be appropriately combined.

The solid line graph shown in FIG. 7B shows the change in the vehicle speed V when the average value V _AVE of the absolute speed V _ACT of the preceding vehicle 20 is updated as needed. On the other hand, the value of the average value _VAVE may be calculated at the start of the fixed speed control, and the value may be fixed for a certain period of time (for example, several tens of seconds). In this case, as shown in FIG. 7 (C), the time t ₁ after the vehicle speed V constant-speed control is started becomes constant speed. Therefore, the traveling state of the vehicle 10 can be stabilized, and the traveling feeling can be improved.

  The settings shown in FIGS. 4 and 5 are for setting the speed range and the distance range based on the vehicle speed V. However, the speed range and the distance range may be set based on parameters other than the vehicle speed V. For example, it is conceivable to set a speed range and a distance range based on the inter-vehicle distance D, road surface gradient, legal speed, road surface condition, and the like in addition to the vehicle speed V. With such a setting, the driving range in which the fixed speed control is performed can be optimized, and the traveling stability of the vehicle 10 can be further improved.

REFERENCE SIGNS LIST 1 driving support device 2 acquisition unit 3 calculation unit 4 control unit 10 own vehicle 14 vehicle speed sensor 15 radar device 20 preceding vehicle
D Distance between vehicles
V vehicle speed
V _REL relative speed
V _ACT absolute speed
V _AVE average
V ₀ predetermined vehicle speed
V _TGT target vehicle speed
D _TGT target distance

Claims (6)

In a driving support device that performs a follow-up control that adjusts the driving force or the braking force of the own vehicle so that the inter-vehicle distance to the preceding vehicle becomes the target distance,
An acquisition unit that acquires the vehicle speed of the host vehicle, the relative speed of the preceding vehicle with respect to the host vehicle, the inter-vehicle distance, and the absolute speed of the preceding vehicle;
A calculating unit that calculates an average value of the absolute speed within a predetermined period,
When the relative speed is within a predetermined speed range including 0 and the inter-vehicle distance is within a predetermined distance range including the target distance, the vehicle speed is reduced to the average value instead of the following control. A driving unit for performing a fixed speed control for adjusting the driving force or the braking force. The said control part performs the following control, when the said relative speed is out of the said predetermined speed range, or when the said inter-vehicle distance is out of the said predetermined distance range, The said control is characterized by the above-mentioned. The driving support device according to claim 1. The driving support device according to claim 1, wherein the average value is a moving average value of the absolute speed within the predetermined period. The driving support device according to any one of claims 1 to 3, wherein the control unit performs the fixed speed control when the vehicle speed is lower than a predetermined vehicle speed. The driving support device according to any one of claims 1 to 4, wherein the predetermined distance range is set so as to increase as the vehicle speed increases. The driving support device according to any one of claims 1 to 5, wherein the predetermined speed range is set so as to increase as the vehicle speed increases.

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