Vehicle driving assistance systems

Abstract

To provide a driving support apparatus for a vehicle, capable of performing appropriate travel control taking into account a traffic flow including a following vehicle.SOLUTION: When an own vehicle travel path is congested, a travel_ECU 14 sets an extended target preceding inter-vehicle distance Lpt' and a target following inter-vehicle distance Lft, in addition to a target preceding inter-vehicle distance Lpt, calculates target acceleration A(Lf) for maintaining a following inter-vehicle distance Lf at the target following inter-vehicle distance Lft, and determines whether to permit an own vehicle M to accelerate or decelerate on the basis of a relative relationship between a preceding inter-vehicle distance Lp and the extended target preceding inter-vehicle distance Lpt'. The travel_ECU 14 performs acceleration control using the target acceleration A(Lf) when the target acceleration A(Lf) is a value on an acceleration side and when it is determined that acceleration is permitted, and performs deceleration control using the target acceleration A(Lf) when the target acceleration A(Lf) is a value on a deceleration side and when it is determined that deceleration is permitted.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a driving support device for a vehicle that causes the host vehicle to travel following a preceding vehicle.

Background Art

[0002] In recent years, in vehicles such as automobiles, in order to reduce the burden of the driver's driving operation and improve safety, a driving support device for assisting the driver's driving operation has been put into practical use. The driving support control by this driving support device is basically realized by including a following inter-vehicle distance control (ACC: Adaptive Cruise Control) function, an active lane keep centering (ALKC) control function, and the like.

[0003] By having the ACC function, when there is no preceding vehicle, the driving support device performs a constant speed driving control to maintain the set vehicle speed set by the driver or the like. Further, when the driving support device detects a preceding vehicle, it performs a following driving control while maintaining a predetermined inter-vehicle distance from the preceding vehicle.

[0004] Furthermore, in recent driving support controls, the application range of the ACC function has been extended to traffic jam control in a low-speed range (0 km / h to...). In such driving support control, it is particularly desirable to perform a driving control that takes into account not only the behavior of the preceding vehicle but also the behavior of the following vehicle. On the other hand, for example, in Patent Document 1, when there is a risk that the following vehicle will collide with the host vehicle, a technique is disclosed in which the inter-vehicle distance (target inter-vehicle distance) between the host vehicle and the preceding vehicle is automatically reduced to ensure the inter-vehicle distance between the host vehicle and the following vehicle.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] However, if control is implemented to reduce the target distance between the vehicle in front and the vehicle ahead, as in the technology disclosed in Patent Document 1 mentioned above, there is a risk that it will be difficult to maintain a sufficient distance from the vehicle in front.

[0007] On the other hand, in recent years, with the increasing prevalence and sophistication of driver assistance systems, there is a growing demand for driving control that takes into account the flow of traffic, including following vehicles, especially during congestion.

[0008] The present invention aims to provide a vehicle driver assistance device that can perform appropriate driving control while taking into account traffic flow, including following vehicles. [Means for solving the problem]

[0009] A vehicle driving assistance device according to one aspect of the present invention comprises: a driving environment recognition means for recognizing external driving environment information including the front and rear of the vehicle; a target distance setting means for setting a target distance to a preceding vehicle when a preceding vehicle is recognized based on the driving environment information; and a driving control means for performing driving control to maintain the distance to the preceding vehicle from the vehicle to the preceding vehicle at the target distance to the vehicle, wherein the target distance setting means sets the target distance to the vehicle when the vehicle's road is congested. and a distance that can prevent other vehicles from cutting in front of the vehicle in question. Set distance toThe system sets an extended target distance for the preceding vehicle and a target distance for the following vehicle. When the vehicle's road is congested, the driving control means calculates a target acceleration to maintain the distance from the vehicle to the following vehicle at the target distance. Based on the relative relationship between the preceding vehicle distance and the extended target distance for the preceding vehicle, it determines whether to allow acceleration or deceleration for the vehicle. When the target acceleration is an acceleration value and acceleration is permitted, it performs acceleration control using the target acceleration. When the target acceleration is a deceleration value and deceleration is permitted, it performs deceleration control using the target acceleration. A vehicle driving assistance device according to one aspect of the present invention comprises: a driving environment recognition means for recognizing external driving environment information including the front and rear of the vehicle; a target distance setting means for setting a target distance to a preceding vehicle when a preceding vehicle is recognized based on the driving environment information; and a driving control means for performing driving control to maintain the distance to the preceding vehicle from the vehicle to the preceding vehicle at the target distance to a preceding vehicle. The target distance setting means sets an extended target distance by extending the target distance to a preceding vehicle when the vehicle's road is congested, sets a target following distance for a following vehicle, and sets a fixed value that has been set in advance as the target following distance. Furthermore, based on the relative relationship between the own vehicle and the following vehicle, the target following distance is corrected, and when the vehicle's road is congested, the driving control means calculates a target acceleration to maintain the following distance from the own vehicle to the following vehicle at the target following distance, and determines whether to allow acceleration or deceleration for the own vehicle based on the relative relationship between the preceding distance and the extended target preceding distance, and performs acceleration control using the target acceleration when the target acceleration is an acceleration value and acceleration is permitted, and performs deceleration control using the target acceleration when the target acceleration is a deceleration value and deceleration is permitted. A vehicle driving assistance device according to one aspect of the present invention comprises: a driving environment recognition means for recognizing external driving environment information including the front and rear of the vehicle; a target inter-vehicle distance setting means for setting a target inter-vehicle distance to a preceding vehicle when a preceding vehicle is recognized based on the driving environment information; and a driving control means for performing driving control to maintain the inter-vehicle distance from the vehicle to the preceding vehicle at the target inter-vehicle distance, wherein when the vehicle's driving path is congested, the target inter-vehicle distance setting means sets an extended target inter-vehicle distance by extending the target inter-vehicle distance by a set distance, and also sets a target following distance to a following vehicle, and the driving control means When the vehicle's travel path is congested, the traffic control means calculates a target acceleration to maintain the distance between the vehicle and the following vehicle at the target distance between vehicles, and, based on the relative relationship between the preceding vehicle and the extended target preceding vehicle, determines whether to allow acceleration or deceleration for the vehicle, reflecting the relative speed between the vehicle and the preceding vehicle. When the target acceleration is an acceleration value and acceleration is permitted, acceleration control is performed using the target acceleration. When the target acceleration is a deceleration value and deceleration is permitted, deceleration control is performed using the target acceleration. [Effects of the Invention]

[0010] According to the vehicle driving assistance device of the present invention, appropriate driving control can be performed while taking into account the traffic flow, including following vehicles. [Brief explanation of the drawing]

[0011] [Figure 1] Schematic diagram of the driver assistance system [Figure 2] Diagram illustrating the monitoring areas of the stereo camera and radar. [Figure 3] Map showing the relationship between leading speed and target following distance. [Figure 4] Map showing the relationship between following distance and target acceleration. [Figure 5] Map for determining whether to allow acceleration or deceleration for the vehicle itself. [Figure 6] Flowchart showing the following vehicle distance control routine [Figure 7] Flowchart showing the driving control subroutine [Figure 8] Flowchart showing the routine for correcting the target distance to the following vehicle. [Figure 9] An explanatory diagram showing the behavior of your vehicle in relation to preceding and following vehicles during traffic congestion. [Figure 10]Explanatory diagram showing the behavior of the host vehicle with respect to the preceding vehicle and the following vehicle during traffic congestion [Figure 11] Explanatory diagram showing the behavior of the host vehicle with respect to the preceding vehicle and the following vehicle during traffic congestion

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of one aspect of the present invention will be described in detail with reference to the drawings. In the drawings used in the following description, in order to make each component recognizable on the drawing, the scale is different for each component. Therefore, the present invention is not limited only to the quantity of the components described in these drawings, the shape of the components, the ratio of the sizes of the components, and the relative positional relationship of each component.

[0013] As shown in FIGS. 1 and 2, the driving support device 1 has, for example, a camera unit 10 fixed to the center of the front part and the upper part inside the vehicle (host vehicle) M.

[0014] This camera unit 10 is configured to include a stereo camera 11, an image processing unit (IPU) 12, an image recognition unit (image recognition_ECU) 13, and a driving control unit (driving_ECU) 14.

[0015] The stereo camera 11 has a main camera 11a and a sub-camera 11b. The main camera 11a and the sub-camera 11b are configured to have an imaging element such as a CMOS. These main camera 11a and sub-camera 11b are arranged at symmetric positions with respect to the center in the vehicle width direction.

[0016] The main camera 11a and the sub-camera 11b perform stereo imaging of the driving environment in the forward area Af outside the vehicle (see FIG. 2) from different viewpoints. The imaging cycles of these main camera 11a and sub-camera 11b are synchronized with each other.

[0017] The IPU 12 processes the driving environment image captured by the stereo camera 11 according to a predetermined method. This allows the IPU 12 to detect the edges of various objects represented in the image, such as three-dimensional objects and road markings. The IPU 12 then calculates distance information from the positional displacement of corresponding edges in the left and right images. Based on this, the IPU 12 generates image information (distance image information) that includes distance information.

[0018] The image recognition ECU13 determines the road curvature [1 / m] of the lane markings that demarcate the left and right sides of the lane in which the vehicle M is traveling (the vehicle's path), and the width between the left and right lane markings (lane width), based on distance image information received from the IPU12. The image recognition ECU13 also determines the road curvature and the width between the left and right lane markings of adjacent lanes to the lane in which the vehicle M is traveling. Various methods are known for determining these road curvatures and lane widths. For example, the image recognition ECU13 performs a luminance-based binarization process on each pixel in the distance image. This allows the image recognition ECU13 to extract candidate points for lane markings on the road. The image recognition ECU13 then performs a curve approximation using the least squares method or the like on the extracted sequence of candidate points for lane markings. This allows the image recognition ECU13 to determine the curvature of the left and right lane markings for each predetermined section. Furthermore, the image recognition ECU13 calculates the lane width from the difference in curvature between the left and right lane markings.

[0019] Furthermore, the image recognition ECU13 performs predetermined pattern matching on the distance image information. This allows the image recognition ECU13 to recognize three-dimensional objects such as guardrails, curbs, median strips, and surrounding vehicles along the road. In this recognition of three-dimensional objects by the image recognition ECU13, for example, the type of object, the distance to the object, the speed of the object, and the relative speed between the object and the vehicle M are recognized.

[0020] The various pieces of information recognized by the image recognition ECU13 are output to the driving ECU14 as driving environment information.

[0021] Thus, in this embodiment, the image recognition ECU 13, together with the stereo camera 11 and the IPU 12, corresponds to a specific example of a driving environment recognition means for recognizing information about the driving environment outside the vehicle.

[0022] The ECU14 is a control unit for the overall control of the driver assistance system 1.

[0023] This driving ECU14 is connected to various control units, including the cockpit control unit (CP_ECU)21, the engine control unit (E / G_ECU)22, the transmission control unit (T / M_ECU)23, the brake control unit (BK_ECU)24, and the power steering control unit (PS_ECU)25, via an in-vehicle communication line such as CAN (Controller Area Network).

[0024] Furthermore, the driving ECU14 is connected to various sensors, including a locator unit 36, a left front side sensor 37lf, a right front side sensor 37rf, a left rear side sensor 37lr, and a right rear side sensor 37rr.

[0025] The CP_ECU21 is connected to a Human-Machine Interface (HMI)31 located around the driver's seat. The HMI31 includes, for example, operation switches for setting and executing various driver assistance controls, a mode switch for switching between driver assistance modes, a steering touch sensor for detecting the driver's steering state, a turn signal switch, a driver monitoring system (DMS) for driver facial recognition and gaze detection, a touch panel display, a combination meter, and a speaker.

[0026] When CP_ECU21 receives a control signal from Driving_ECU14, it appropriately notifies the driver of various information such as various warnings for the preceding vehicle, the status of driver assistance control implementation, and the driving environment of its own vehicle M, through displays and voice prompts via HMI31.

[0027] Furthermore, the CP_ECU25 outputs various input information to the Driving_ECU14, such as the on or off operation status of various driver assistance controls input by the driver via the HMI31, the set vehicle speed (set speed) Vs for the vehicle M, and the operation status of the turn signal switch.

[0028] The output side of the E / G_ECU22 is connected to the throttle actuator 32 of the electronically controlled throttle, etc. Various sensors, such as an accelerator sensor (not shown), are connected to the input side of the E / G_ECU22.

[0029] The E / G_ECU22 controls the throttle actuator 32 based on control signals from the Driving_ECU14 or detection signals from various sensors. This allows the E / G_ECU22 to adjust the amount of intake air for the engine and generate the desired engine output. The E / G_ECU22 also outputs signals such as the accelerator opening angle detected by the various sensors to the Driving_ECU14.

[0030] The output side of T / M_ECU23 is connected to the hydraulic control circuit 33. Various sensors, such as a shift position sensor (not shown), are connected to the input side of T / M_ECU23. Based on the engine torque signal estimated by E / G_ECU22 and the detection signals from the various sensors, T / M_ECU23 performs hydraulic control on the hydraulic control circuit 33. As a result, T / M_ECU23 operates the friction engagement elements and pulleys provided in the automatic transmission to shift the engine output to the desired gear ratio. T / M_ECU23 also outputs signals such as the shift position detected by the various sensors to the driving_ECU14.

[0031] A brake actuator 34 is connected to the output side of the BK_ECU24. The brake actuator 34 adjusts the brake fluid pressure output to the brake wheel cylinders located on each wheel. Various sensors, such as a brake pedal sensor, yaw rate sensor, longitudinal acceleration sensor, and vehicle speed sensor (not shown), are connected to the input side of the BK_ECU24.

[0032] The BK_ECU24 controls the brake actuator 34 based on control signals from the Driving_ECU14 or detection signals from various sensors. This allows the BK_ECU24 to appropriately generate braking force on each wheel for forced braking control and yaw rate control of the vehicle M. The BK_ECU24 also outputs signals such as brake operation status, yaw rate, longitudinal acceleration, and vehicle speed (vehicle speed) detected by various sensors to the Driving_ECU14.

[0033] The output side of the PS_ECU25 is connected to the electric power steering motor 35. The electric power steering motor 35 applies steering torque to the steering mechanism through the rotational force of the motor. Various sensors, such as a steering torque sensor and a steering angle sensor, are connected to the input side of the PS_ECU25.

[0034] The PS_ECU25 controls the electric power steering motor 35 based on control signals from the driving_ECU14 or detection signals from various sensors. This causes the PS_ECU25 to generate steering torque for the steering mechanism. The PS_ECU25 also outputs signals such as the steering torque and steering angle detected by the various sensors to the driving_ECU14.

[0035] The locator unit 36 ​​comprises a GNSS sensor 36a, a high-precision road map database (road map DB) 36b, and a receiver 36c.

[0036] The GNSS sensor 36a determines the position of the vehicle M (latitude, longitude, altitude, etc.) by receiving positioning signals transmitted from multiple positioning satellites.

[0037] The road map DB36b is a large-capacity storage medium such as an HDD. This road map DB36b stores high-precision road map information (dynamic map). The road map information includes, for example, lane data necessary for autonomous driving, such as lane width data, lane center position coordinate data, lane direction angle data, and speed limit data. The lane data is stored at intervals of several meters for each lane on the road map. For example, based on a request signal from the driving_ECU14, the road map DB36b outputs road map information for a set range based on the vehicle's position determined by the GNSS sensor 36a as driving environment information to the driving_ECU14.

[0038] The receiver 36c receives various types of traffic information transmitted from the Road Traffic Information Communication System (VICS®: Vehicle Information Communication System) via, for example, vehicle-to-infrastructure communication. The traffic information received by the receiver 36c includes, for example, congestion information, road restrictions due to accidents or weather, etc.

[0039] Thus, in this embodiment, the road map DB36b, together with the GNSS sensor 36a, constitutes a specific example of a driving environment recognition means for recognizing information about the driving environment outside the vehicle.

[0040] The left front side sensor 37lf and the right front side sensor 37rf are, for example, composed of millimeter-wave radar. These left front side sensor 37lf and the right front side sensor 37rf are, for example, located on the left and right sides of the front bumper, respectively. The left front side sensor 37lf and the right front side sensor 37rf detect three-dimensional objects in the left and right diagonally forward and lateral regions Alf and Arf (see Figure 2) of the vehicle M, which are difficult to recognize with the image from the stereo camera 11, as driving environment information.

[0041] The left rear side sensor 37lr and the right rear side sensor 37rr are, for example, composed of millimeter-wave radar. These left rear side sensor 37lr and the right rear side sensor 37rr are, for example, located on the left and right sides of the rear bumper, respectively. The left rear side sensor 37lr and the right rear side sensor 37rr detect three-dimensional objects in the left and right diagonal side and rear areas Alr and Arr (see Figure 2) of the vehicle M, which are difficult to recognize with the left front side sensor 37lf and the right front side sensor 37rf, as driving environment information.

[0042] In this case, if each radar is composed of millimeter-wave radar, the millimeter-wave radar primarily detects three-dimensional objects such as vehicles traveling alongside and following vehicles by analyzing the reflected waves from objects in response to the emitted radio waves. Specifically, each radar detects information about the three-dimensional object, such as the width of the object, the position of a representative point of the object (relative position to the vehicle M), and its speed.

[0043] Thus, in this embodiment, the left front side sensor 37lf, the right front side sensor 37rf, the left rear side sensor 37lr, and the right rear side sensor 37rr correspond to specific examples of driving environment recognition means for recognizing driving environment information outside the vehicle.

[0044] Furthermore, the coordinates of each external object included in the driving environment information recognized by the image recognition_ECU13, locator unit 36, left front side sensor 37lf, right front side sensor 37rf, left rear side sensor 37lf, and right rear side sensor 37rr are all converted by the driving_ECU14 into coordinates in a three-dimensional coordinate system (see Figure 2) with the center of the vehicle M as the origin.

[0045] The driving ECU14 has several driving modes: a manual driving mode, a first driving control mode and a second driving control mode, and a stow mode. These driving modes can be selectively switched in the driving ECU14 based on, for example, the operation status of the mode switching switch provided on the HMI31.

[0046] Here, manual driving mode refers to a driving mode that requires the driver to maintain steering. In other words, manual driving mode is a driving mode in which the vehicle M is driven according to driving operations such as steering, accelerating, and braking performed by the driver.

[0047] The first driving control mode is also a driving mode that requires the driver to maintain steering. In other words, the first driving control mode is a semi-autonomous driving mode that drives the vehicle M while reflecting the driver's driving operations. This first driving control mode is realized, for example, by the driving_ECU14 outputting various control signals to the E / G_ECU22, BK_ECU24, and PS_ECU25. In the first driving control mode, adaptive cruise control (ACC), active lane keep centering control (ALKC), active lane keep bouncing (ALKB), and lane change control are mainly performed in appropriate combinations. As a result, the vehicle M is able to drive along the target driving path.

[0048] Here, the adaptive cruise control is basically performed based on driving environment information input from the image recognition ECU13, etc.

[0049] To explain in more detail, if the image recognition ECU14 or similar system does not recognize a preceding vehicle P in front of the vehicle M, the driving ECU14 performs constant speed driving control as part of the follow distance control. In this constant speed driving control, the driving ECU14 sets the set vehicle speed Vs input by the driver as the target vehicle speed Vt. Then, the driving ECU14 performs acceleration and deceleration control for the vehicle M based on the target vehicle speed Vt. As a result, the driving ECU14 maintains the vehicle speed V of the vehicle M at the set vehicle speed Vs.

[0050] On the other hand, if the image recognition ECU 13 or the like recognizes a preceding vehicle P in front of the own vehicle M, the driving ECU 14 performs follow-up driving control as part of follow-up distance control. In this follow-up driving control, the driving ECU 14 sets a target distance (target preceding distance Lpt) based on the vehicle speed Vp of the preceding vehicle P. This target preceding distance Lpt is set by referring to a map (see solid line in Figure 3) that is pre-set in the driving ECU 14, for example. This target preceding distance Lpt is set so that, for example, it becomes a larger value as the preceding vehicle speed Vp increases.

[0051] The driving ECU14 then performs acceleration and deceleration control for its own vehicle M based on the target distance Lpt between vehicles. In this way, the driving ECU14 basically maintains the distance Lp between vehicles at the target distance Lpt between vehicles, causing the own vehicle M to follow the preceding vehicle P.

[0052] However, when the vehicle's road is congested, the driving_ECU14 calculates an extended target distance Lpt' in addition to the target distance Lpt. This extended target distance Lpt' is set by referring to a map (see dashed line in Figure 3) that is pre-set in the driving_ECU14, for example. For example, this extended target distance Lpt' is set to the target distance Lpt plus a pre-set distance ΔLpt. In this embodiment, the distance ΔLpt is a fixed value, but it is also possible to make the distance ΔLpt a variable value, such as increasing it as the speed Vp of the vehicle ahead increases. It is desirable that such an extended target distance ΔLpt' be set to a distance that can suppress other vehicles cutting in front of the vehicle M, based on pre-conducted driving tests, etc.

[0053] Furthermore, the Driving_ECU14 sets a target following distance Lft for the following vehicle F. This target following distance Lft is, for example, a fixed value pre-set in the Driving_ECU14. Here, the target following distance Lft is, for example, a distance at which the driver of the following vehicle F in traffic congestion can psychologically reduce the frequency of braking relative to their own vehicle M, and is set based on pre-conducted driving tests, etc. The Driving_ECU14 can also appropriately adjust the target following distance Lft based on the relative relationship between the own vehicle M and the following vehicle F (for example, the average value of the following distance Lf).

[0054] Then, once the extended target distance ahead Lpt' and the target distance behind Lft are set, the driving ECU14 controls the distance ahead Lp based on the extended target distance ahead Lpt', and performs acceleration and deceleration control to maintain the distance behind Lf from its own vehicle M to the following vehicle F at the target distance behind Lft as much as possible.

[0055] To perform this acceleration and deceleration control, the driving ECU 14 calculates a target acceleration A(Lf) based on the following distance Lf, in order to maintain the following distance Lf at a target following distance Lft. Specifically, this calculation of the target acceleration A(Lf) is performed by referring to a pre-set map, etc. That is, for example, as shown in Figure 4, the driving ECU 14 has a map pre-set and stored for calculating the target acceleration A(Lf) according to the following distance Lf. Based on this map, the driving ECU 14 calculates the target acceleration A(Lf) according to the following distance Lf. This target acceleration A(Lf) is set such that, for example, the vehicle M is accelerated with a large acceleration as the following distance Lf becomes smaller than the target following distance Lft, and the vehicle M is decelerated with a large deceleration as the following distance Lf becomes larger than the target following distance Lft. In order to suppress rapid acceleration, it is desirable to set the upper limit of the target acceleration A(Lf) to, for example, 0.1G or less.

[0056] Furthermore, the driving ECU14 determines whether or not to allow acceleration or deceleration for the vehicle M based on the relative relationship between the vehicle M and the preceding vehicle P. This acceleration / deceleration permission determination is basically made based on the relative relationship between the distance between the vehicle M and the preceding vehicle P (preceding vehicle distance Lp) and the extended target preceding vehicle distance Lpt'. However, it is desirable to reflect the relative speed between the vehicle M and the preceding vehicle P (preceding vehicle relative speed Vrp (=Vp-V)) in this acceleration / deceleration permission determination.

[0057] More specifically, the decision to permit acceleration or deceleration is made by referring to, for example, a pre-configured map. For this reason, the driving ECU14 stores a map (see Figure 5) for determining whether to permit acceleration or deceleration for the vehicle M based on, for example, the distance to the preceding vehicle Lp and the relative speed Vrp of the preceding vehicle, which is pre-configured and stored for each extended distance to the preceding vehicle Lpt'.

[0058] As is clear from Figure 5, in this judgment map, basically, regions where acceleration is permitted (acceleration permitted region) and regions where deceleration is permitted (deceleration permitted region) are set based on the extended target distance to the preceding vehicle Lpt'. In other words, in this judgment map, basically, regions where the distance to the preceding vehicle Lp is greater than the extended target distance to the preceding vehicle Lpt' are set as regions where acceleration is permitted for the vehicle M, and regions where the distance to the preceding vehicle Lp is smaller than the extended target distance to the preceding vehicle Lpt' are set as regions where deceleration is permitted for the vehicle M.

[0059] However, in order to reflect the relative speed Vrp of the preceding vehicle in the acceleration permission determination and deceleration permission determination, an extended region is set in the acceleration permission region and the deceleration permission region, respectively. That is, on the determination map, a portion of the acceleration permission region is extended to a region where the distance Lp between vehicles is smaller than the extended target distance Lpt' between vehicles. This extended acceleration permission region is set to widen as, for example, the relative speed Vrp of the preceding vehicle increases. Also, on the determination map, a portion of the deceleration permission region is extended to a region where the distance Lp between vehicles is larger than the extended target distance Lpt' between vehicles. This extended deceleration permission region is set to widen as, for example, the relative speed Vrp of the preceding vehicle decreases (as it increases towards the negative side).

[0060] Based on this judgment map, the driving ECU14 makes a decision to allow acceleration or deceleration according to the distance Lp and the relative speed Vrp of the vehicle ahead.

[0061] Then, the driving ECU14 calculates a positive target acceleration A(Lf) based on the distance Lf between vehicles, and when it determines that acceleration is permitted based on the distance Lf between vehicles and the relative speed Vrp of the preceding vehicle, it performs acceleration control for its own vehicle M using the target acceleration A(Lf).

[0062] Furthermore, when the driving ECU14 calculates a negative target acceleration A(Lf) based on the distance Lf between vehicles, and when it determines that deceleration is permitted based on the distance Lf between vehicles and the relative speed Vrp of the preceding vehicle, it performs deceleration control for its own vehicle M using the target acceleration A(Lf).

[0063] Thus, in this embodiment, the driving ECU14 corresponds to a specific example of a target inter-vehicle distance setting means and a driving control means.

[0064] Furthermore, lane centering control and lane departure prevention control are basically performed based on driving environment information input from at least one of the image recognition ECU 13 and the locator unit 36. That is, the driving ECU 14 sets a target path Rm along the left and right lane markings in the center of the vehicle's driving lane, based on lane marking information included in the driving environment information, for example. Then, based on the target path Rm, the driving ECU 14 maintains the vehicle M in the center of the lane by performing feedforward control and feedback control for steering. In addition, when the driving ECU 14 determines that there is a high possibility that the vehicle M will deviate from its driving lane due to the effects of crosswinds or road banking, it suppresses lane departure by forcibly controlling the steering.

[0065] The second driving control mode is a driving mode in which the vehicle M is driven without requiring steering, acceleration, or braking by the driver. In other words, the second driving control mode is an autonomous driving mode in which the vehicle M is driven autonomously without requiring any driving operation by the driver. This second driving control mode is realized, for example, by the driving_ECU14 outputting various control signals to the E / G_ECU22, BK_ECU24, and PS_ECU25. In the second driving control mode, the preceding vehicle following control, lane centering control, and lane departure prevention control are mainly performed in appropriate combinations. As a result, the vehicle M is able to drive according to the target route (route map information).

[0066] The escape mode is a mode for automatically stopping the vehicle M on the roadside or elsewhere. This escape mode is executed, for example, when driving in the second driving control mode becomes impossible to continue and it is not possible to take over driving control to the driver (i.e., it is not possible to transition to manual driving mode or the first driving control mode).

[0067] In addition, in each of the above driving modes, the traveling ECU 14 can appropriately perform emergency braking control (collision damage mitigation brake (AEB: Autonomous Emergency Braking)) or the like on obstacles such as vehicles that are likely to collide with the host vehicle M.

[0068] Basically, the emergency braking control is control for avoiding a collision with an obstacle existing ahead on the target traveling path of the host vehicle M by braking.

[0069] At the time of this emergency braking control, the traveling ECU 14 detects obstacles such as a preceding vehicle or a stopped vehicle existing on the target traveling path of the host vehicle M based on the traveling environment information. Further, the traveling ECU 14 calculates the collision prediction time TTC with respect to the obstacle. This longitudinal collision prediction time TTC is calculated based on the relative speed and relative distance between the host vehicle M and the obstacle.

[0070] Then, when the longitudinal collision prediction time TTC becomes smaller than a preset first threshold value Tth1, the traveling ECU 14 executes primary braking control. When the primary braking control is started, the traveling ECU 14 decelerates the host vehicle M using a preset first target deceleration (for example, 0.4G).

[0071] Furthermore, when the longitudinal collision prediction time TTC becomes smaller than a preset second threshold value Tth2 (where Tth2 < Tth1), the traveling ECU 14 executes secondary braking control. When the secondary braking control is started, the traveling ECU 14 decelerates the host vehicle M using a preset second target deceleration (for example, 1G) until the relative speed with the obstacle becomes "0".

[0072] Next, the following vehicle distance control will be described according to the flowchart of the following vehicle distance control routine shown in FIG. 6. This following driving control routine is repeatedly performed at set time intervals in the traveling ECU 14.

[0073] When the routine starts, the driving_ECU14 checks in step S101 whether the ACC function is turned on. In this embodiment, for example, if the first driving control mode or the second driving control mode is selected as the driving mode, it is determined that the ACC function is turned on. Alternatively, even if the manual driving mode is selected, if, for example, the driver or the like performs an ON operation for the ACC function on the HMI31, it is determined that the ACC function is turned on.

[0074] Then, in step S101, if it is determined that the ACC function is turned off (step S101: NO), the driving_ECU14 exits the routine.

[0075] On the other hand, if it is determined in step S101 that the ACC function is turned on (step S101: YES), the driving ECU14 proceeds to step S102.

[0076] In step S102, the driving ECU 14 sets the target distance Lpt to the preceding vehicle as appropriate, and then proceeds to step S103. That is, if the image recognition ECU 13 or the like recognizes a preceding vehicle P in front of the vehicle M, the driving ECU 14 refers to a pre-set map (see Figure 3) or the like and sets the target distance Lpt to the preceding vehicle according to the speed Vp of the preceding vehicle. If the preceding vehicle P is not recognized in front of the vehicle M, the driving ECU 14 proceeds directly to step S103.

[0077] In step S103, the driving ECU 14 checks whether the road the vehicle M is traveling on is congested. This congestion determination can be made based on driving environment information recognized, for example, by the image recognition ECU 13. That is, if the image recognition ECU 13 or the like recognizes that multiple vehicles are lined up in front of the preceding vehicle P, and the speed of the preceding vehicle Vp is below a preset speed, the driving ECU 14 determines that the vehicle's road is congested. Alternatively, the driving ECU 14 can also make a congestion determination based on information from, for example, VICS (registered trademark).

[0078] Then, in step S103, if it is determined that the vehicle's travel path is not congested (step S103: NO), the driving ECU14 proceeds to step S104. After calculating the target acceleration A of the vehicle, the driving ECU14 proceeds to step S113.

[0079] In other words, in step S104, the driving ECU 14 checks whether or not there is a preceding vehicle P in front of its own vehicle M. If there is no preceding vehicle P, the driving ECU 14 calculates a target acceleration A(Vs) to maintain its own vehicle speed V at the set vehicle speed Vs input by the driver.

[0080] Furthermore, if a preceding vehicle P exists, the driving_ECU14 calculates the target acceleration A(Lp) to maintain the distance Lp between vehicles at the preceding vehicle at the target distance Lpt. That is, the driving_ECU14 calculates the target acceleration A(Lp) based on, for example, the following equation (1).

[0081] A(Lp) = ap + ((V - Vp) 2 / (Lp-Lpt)) …(1)

[0082] Here, in equation (1), ap is the acceleration of the preceding vehicle P.

[0083] On the other hand, if in step S103 it is determined that the vehicle's route is congested (step S103: YES), the driving_ECU14 proceeds to step S105. Then, in step S105, the driving_ECU14 refers to a pre-set map, etc., to set the extended target distance ahead Lpt' and the target distance behind Lft, and then proceeds to step S106.

[0084] In step S106, the driving ECU14 calculates a target acceleration A(Lf) based on the target following distance Lft. That is, the driving ECU14 calculates a target acceleration A(Lf) to converge the following distance Lf to the target following distance Lft, for example, by referring to a map such as the one shown in Figure 3.

[0085] In the subsequent step S107, the driving ECU14 refers to, for example, a map corresponding to the currently set target distance to the preceding vehicle Lpt', and makes an acceleration / deceleration determination based on the relative relationship between its own vehicle M and the preceding vehicle P. That is, the driving ECU14 refers to the map, etc., and makes a determination to allow acceleration or deceleration for its own vehicle M based on the distance to the preceding vehicle Lp and the relative speed Vrp of the preceding vehicle.

[0086] Then, in step S107, if a determination is made to permit acceleration for the vehicle M, the driving_ECU14 proceeds to step S108. On the other hand, in step S107, if a determination is made to permit deceleration for the vehicle, the driving_ECU14 proceeds to step S109.

[0087] When the process moves from step S107 to step S108, the driving ECU14 checks whether the target acceleration A(Lf) calculated in step S106 is greater than "0", that is, whether the target acceleration A(Lf) is a positive value, which is an acceleration value.

[0088] Then, in step S108, if it is determined that the target acceleration A(Lf) is greater than "0" (step S108: YES), the driving ECU14 proceeds to step S113 while maintaining the current target acceleration A(Lf).

[0089] On the other hand, if in step S108 it is determined that the target acceleration A(Lf) is "0" or less (step S108: NO), the driving ECU14 proceeds to step S110.

[0090] When the vehicle moves from step S108 to step S110, the driving ECU 14 changes the target acceleration A(Lf) to "0" and then proceeds to step S113. In other words, the driving ECU 14 corrects the target acceleration A(Lf) to "0" to prevent unnecessary deceleration from occurring when acceleration is permitted based on the relationship between the vehicle M and the preceding vehicle P.

[0091] Furthermore, when the system proceeds from step S107 to step S109, the driving ECU14 checks whether the target acceleration A(Lf) calculated in step S106 is less than "0", that is, whether the target acceleration A(Lf) is a negative value, which is a deceleration value.

[0092] Then, in step S109, if it is determined that the target acceleration A(Lf) is "0" or greater (step S109: NO), the driving ECU14 proceeds to step S110.

[0093] When the vehicle moves from step S109 to step S110, the driving ECU 14 changes the target acceleration A(Lf) to "0" and then proceeds to step S113. In other words, the driving ECU 14 corrects the target acceleration A(Lf) to "0" to prevent unnecessary acceleration from occurring when deceleration is permitted based on the relationship between the vehicle M and the preceding vehicle P.

[0094] On the other hand, if in step S109 it is determined that the target acceleration A(Lf) is less than "0" (step S109: YES), the driving ECU14 proceeds to step S111 while maintaining the current target acceleration A(Lf).

[0095] In step S111, the driving ECU14 calculates, for example, the target acceleration A(Lp) to maintain the distance Lp between vehicles ahead at the target distance Lpt using equation (1) above, and then proceeds to step S112.

[0096] In step S112, the driving ECU14 selects the smaller of the target acceleration A(Lp) calculated in step S111 and the target acceleration A(Lf) calculated in step S106 (the larger value on the deceleration side) as the target acceleration A, and then proceeds to step S113.

[0097] When the process proceeds from step S104, step S108, step S110, or from step S112 to step S113, the driving ECU 14 performs driving control (i.e., acceleration / deceleration control) for its own vehicle M using the target acceleration A, and then exits the routine.

[0098] The driving control for the vehicle M is performed, for example, according to the flowchart of the driving control subroutine shown in Figure 7. When the subroutine starts, the driving_ECU14 checks whether the current vehicle speed V is "0", that is, whether the vehicle M is stopped following the preceding vehicle P.

[0099] Then, in step S201, if it is determined that the vehicle M is not in a stationary state (step S201: NO), the driving ECU14 proceeds to step S204.

[0100] On the other hand, in step S201, if it is determined that the vehicle M is stationary (step S201: YES), the driving ECU 14 checks whether the distance Lp between vehicles is greater than the preset follow-start distance Lstart.

[0101] Then, in step S202, if it is determined that the distance Lp between vehicles is less than or equal to the following start distance Lstart (step S205: NO), the driving_ECU14 maintains the stationary state of its own vehicle M and then exits the subroutine.

[0102] On the other hand, in step S202, if it is determined that the distance Lp between vehicles is greater than the distance Lstart for following vehicles (step S202: YES), the driving ECU 14 permits the vehicle M to start following the preceding vehicle P, and then proceeds to step S204.

[0103] When step S201 is reached, or when the process proceeds from step S203 to step S204, the driving_ECU14 performs acceleration and deceleration control on the vehicle M based on the currently calculated target acceleration A, and then exits the subroutine. That is, if the target acceleration A is a positive value, the driving_ECU14 generates an acceleration on the vehicle M corresponding to the target acceleration A. On the other hand, if the target acceleration A is a negative value, the driving_ECU14 generates a deceleration on the vehicle M corresponding to the target acceleration A. It is desirable that the driving_ECU14 perform upper and lower limit processing on the target acceleration A in order to prevent sudden acceleration and deceleration of the vehicle M.

[0104] By the way, when correcting the target following distance Lft based on the relative relationship between the vehicle M and the following vehicle F, the driving_ECU14 executes, for example, the flowchart of the target following distance correction routine shown in Figure 8. This routine is repeatedly executed by the driving_ECU14 at set intervals.

[0105] When the routine starts, the driving ECU14 checks in step S301 whether the vehicle's road is congested or not.

[0106] Then, in step S301, if it is determined that the vehicle's route is not congested (step S301: NO), the driving ECU14 proceeds to step S303.

[0107] On the other hand, if step S301 determines that the vehicle's route is congested (step S301: YES), the driving ECU14 proceeds to step S302.

[0108] In step S302, the driving ECU14 checks whether the current following vehicle F is the same following vehicle as the one in front.

[0109] Then, in step S302, if it is determined that the current following vehicle F is a different vehicle from the one in front (step S302: NO), the driving ECU14 proceeds to step S303.

[0110] When the process moves from step S301, or from step S302 to step S303, the driving ECU14 clears counter C (C←0) which indicates that the same following vehicle F is continuing, and then exits the routine.

[0111] On the other hand, if step S302 determines that the current following vehicle F is the same following vehicle as the previous frame (step S302: YES), the driving ECU14 proceeds to step S304.

[0112] In step S304, the driving ECU14 increments counter C (C←C+1) and then proceeds to step S305.

[0113] In step S305, the driving ECU14 refers to the current counter C and checks whether the same following vehicle F has continued for the set frame.

[0114] Then, in step 305, if it is determined that the same following vehicle F is not continuing the set frame (step S305: NO), the driving_ECU14 exits the routine.

[0115] On the other hand, if step S305 determines that the same following vehicle F is continuing the set frame (step S305: YES), the driving ECU14 proceeds to step S306 and clears counter C (C←0).

[0116] In the following step S307, the driving ECU14 calculates the average value Lfa of the following vehicle distance Lf between set frames, and then proceeds to step S308.

[0117] In step S308, the driving ECU 14 checks whether the calculated average value Lfa of the following vehicle distance is greater than the value obtained by adding a predetermined value ΔL to the target following vehicle distance Lft (that is, whether Lft + ΔL < Lfa).

[0118] And in step S308, when it is determined that the average value Lfa of the following vehicle distance is greater than the value obtained by adding a predetermined value ΔL to the target following vehicle distance Lft (step S308: YES), the driving ECU 14 proceeds to step S309. Then, in step S309, the driving ECU 14 corrects the target following vehicle distance Lft to increase it by a predetermined value ΔL, and then exits the routine.

[0119] On the other hand, in step S308, when it is determined that the average value Lfa of the following vehicle distance is less than or equal to the value obtained by adding a predetermined value ΔL to the target following vehicle distance Lft (step S308: NO), the driving ECU 14 proceeds to step S310.

[0120] In step S310, the driving ECU 14 checks whether the calculated average value Lfa of the following vehicle distance is less than the value obtained by subtracting a predetermined value ΔL from the target following vehicle distance Lft (that is, whether Lft - ΔL > Lfa).<s

[0121] And in step S310, when it is determined that the average value Lfa of the following vehicle distance is less than the value obtained by subtracting a predetermined value ΔL from the target following vehicle distance Lft (step S310: YES), the driving ECU 14 proceeds to step S311. Then, in step S311, the driving ECU 14 corrects the target following vehicle distance Lfr to decrease it by a predetermined value ΔL, and then exits the routine.

[0122] On the other hand, in step S310, when it is determined that the average value Lfa of the following vehicle distance is greater than or equal to the value obtained by subtracting a predetermined value ΔL from the target following vehicle distance Lft (step S310: NO), the driving ECU 14 exits the routine as it is.

[0123] According to this embodiment, when the vehicle's road is congested, the driving ECU 14 sets a target distance ahead Lft, an extended target distance ahead Lft', and a target distance behind Lft. The driving ECU 14 then calculates a target acceleration A(Lf) to maintain the distance behind Lf from the vehicle M to the following vehicle F at the target distance behind Lft, and determines whether to allow acceleration or deceleration for the vehicle M based on the relative relationship between the distance ahead Lp and the extended target distance ahead Lpt'. When the target acceleration A(Lf) is an acceleration value and acceleration is permitted, acceleration control is performed using the target acceleration A(Lf). When the target acceleration A(Lf) is a deceleration value and deceleration is permitted, deceleration control is performed using the target acceleration A(Lf). This enables appropriate driving control that takes into account the traffic flow, including the following vehicle F.

[0124] In other words, during traffic congestion, by setting a target distance Lpt and an extended target distance Lpt' for the preceding vehicle P, a predetermined range of distance can be maintained when the vehicle M follows the preceding vehicle P. Then, within the range of the predetermined distance, by performing acceleration and deceleration control for the following vehicle F, it is possible to achieve appropriate driving control that takes into account the traffic flow, including the following vehicle F, while appropriately maintaining the distance to the preceding vehicle.

[0125] For example, as shown in Figure 9, if the following vehicle F accelerates and the following distance Lf becomes smaller than the target following distance Lft, the driving ECU 14 appropriately accelerates the vehicle M within a range where the preceding distance Lf does not deviate significantly from the extended target preceding distance Lft', thereby maintaining the following distance Lf at the target following distance Lft. This reduces the frequency of unnecessary braking by the following vehicle F and effectively suppresses the chain reaction of braking by vehicles following behind the following vehicle F. Suppressing this chain reaction of braking contributes to alleviating congestion and also contributes to improving fuel efficiency for the overall traffic flow of vehicles following behind the vehicle M.

[0126] In this case, for example, as shown in Figure 10, if the acceleration of the vehicle M causes the distance Lp to the preceding vehicle to become the target distance Lpt, the driving ECU 14 maintains the distance Lp to the preceding vehicle at the target distance Lpt without further acceleration. This ensures that a sufficient distance Lp is maintained even when controlling the distance to the following vehicle F, and effectively prevents the vehicle M from colliding with the preceding vehicle P.

[0127] Furthermore, as shown in Figure 11, for example, if the following distance Lf becomes greater than the target following distance Lft, the driving ECU 14 appropriately decelerates its own vehicle M within a range where the preceding distance Lf does not deviate significantly from the extended target preceding distance Lft', thereby maintaining the following distance Lf at the target following distance Lft. This reduces the frequency of unnecessary acceleration by the following vehicle F. And suppressing such unnecessary acceleration by the following vehicle F ultimately leads to suppressing unnecessary deceleration by the following vehicle F in traffic jams. Therefore, in traffic jams, the chain reaction of braking by vehicles following the following vehicle F can be effectively suppressed.

[0128] Furthermore, the extended target distance Lft' in this embodiment is set within a range that can suppress other vehicles cutting in front of the vehicle M. Therefore, it is possible to suppress the vehicle M from performing emergency braking control due to other vehicles cutting in, and furthermore, it is possible to accurately prevent a chain reaction of emergency braking by following vehicles F and beyond.

[0129] Furthermore, the driving ECU14 can correct the target following distance Lft based on the relative relationship between the vehicle M and the following vehicle F. This allows the driver's feeling when driving the following vehicle F to be reflected in the target following distance Lft, and more effectively suppresses the number of times the following vehicle F brakes (unnecessary acceleration and deceleration).

[0130] In the above-described embodiment, the image recognition_ECU13, driving_ECU14, CP_ECU21, E / G_ECU22, T / M_ECU23, BK_ECU24, PS_ECU25, etc., are composed of a well-known microcomputer equipped with a CPU, RAM, ROM, non-volatile memory, etc., and its peripheral devices, with fixed data such as programs executed by the CPU and data tables pre-stored in the ROM. Note that all or part of the processor's functions may be composed of logic circuits or analog circuits, and the processing of various programs may be realized by electronic circuits such as FPGAs.

[0131] The inventions described in the above embodiments are not limited to those forms, and various modifications can be made in the implementation stage without departing from the gist of the invention. Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriate combinations of the multiple constituent elements disclosed.

[0132] For example, if the problem described can be solved and the effects described can be obtained even if some of the constituent elements shown in each form are removed, then the configuration with the removed constituent elements can be extracted as an invention. [Explanation of Symbols]

[0133] 1. Driving assistance system 10 ... Camera unit 11… Stereo camera 11a ... Main camera 11b ... Sub-camera 12 … IPU 13 … Image Recognition_ECU 14 … Driving_ECU 21 … CP_ECU 22 … E / G_ECU 23 … T / M_ECU 24 … BK_ECU 25 … PS_ECU 31 … HMI 32… Throttle Actuator 33. Hydraulic control circuit 34… Brake actuator 35… Electric power steering motor 36... Locator Unit 36a ... GNSS sensor 36b ... Road map database 36c ... Receiver 37lf… Left front side sensor 37lr… Left rear side sensor 37rf ... Right front side sensor 37rr... Right rear side sensor M... Vehicle (own vehicle) P... Leading vehicle F... Following vehicle

Claims

1. A driving environment recognition means for recognizing external driving environment information including the front and rear of the vehicle, A target distance setting means for setting a target distance to the preceding vehicle when the preceding vehicle is recognized based on the aforementioned driving environment information, The vehicle comprises a driving control means that performs driving control to maintain the distance between the vehicle and the preceding vehicle at the target distance between vehicles, The aforementioned target distance setting means, when the vehicle's road is congested, sets an extended target distance by extending the target distance ahead to a set distance that is sufficient to prevent other vehicles from cutting in front of the vehicle, and also sets a target distance behind the vehicle. The driving control means is characterized in that, when the vehicle's driving path is congested, it calculates a target acceleration to maintain the distance between the vehicle and the following vehicle at the target distance between vehicles, determines whether to allow acceleration or deceleration for the vehicle based on the relative relationship between the preceding vehicle and the extended target preceding vehicle, performs acceleration control using the target acceleration when the target acceleration is an acceleration value and acceleration is permitted, and performs deceleration control using the target acceleration when the target acceleration is a deceleration value and deceleration is permitted.

2. A driving environment recognition means for recognizing external driving environment information including the front and rear of the vehicle, A target distance setting means for setting a target distance to the preceding vehicle when the preceding vehicle is recognized based on the aforementioned driving environment information, The vehicle comprises a driving control means that performs driving control to maintain the distance between the vehicle and the preceding vehicle at the target distance between vehicles, The aforementioned target following distance setting means, when the vehicle's road is congested, sets an extended target following distance by extending the target preceding distance by a set distance, sets a target following distance for the following vehicle, sets a predetermined fixed value as the target following distance, and further corrects the target following distance based on the relative relationship between the vehicle and the following vehicle. The driving control means is characterized in that, when the vehicle's driving path is congested, it calculates a target acceleration to maintain the distance between the vehicle and the following vehicle at the target distance between vehicles, determines whether to allow acceleration or deceleration for the vehicle based on the relative relationship between the preceding vehicle and the extended target preceding vehicle, performs acceleration control using the target acceleration when the target acceleration is an acceleration value and acceleration is permitted, and performs deceleration control using the target acceleration when the target acceleration is a deceleration value and deceleration is permitted.

3. A driving environment recognition means for recognizing external driving environment information including the front and rear of the vehicle, A target distance setting means for setting a target distance to the preceding vehicle when the preceding vehicle is recognized based on the aforementioned driving environment information, The vehicle comprises a driving control means that performs driving control to maintain the distance between the vehicle and the preceding vehicle at the target distance between vehicles, The aforementioned target distance setting means, when the vehicle's road is congested, sets an extended target distance by extending the target distance to the preceding vehicle, and also sets a target distance to the following vehicle. The driving control means is characterized in that, when the vehicle's driving path is congested, it calculates a target acceleration to maintain the distance between the vehicle and the following vehicle at the target distance between vehicles, and based on the relative relationship between the preceding vehicle and the extended target preceding vehicle, it determines whether to allow acceleration or deceleration for the vehicle, reflecting the relative speed between the vehicle and the preceding vehicle, and when the target acceleration is an acceleration value and acceleration is permitted, it performs acceleration control using the target acceleration, and when the target acceleration is a deceleration value and deceleration is permitted, it performs deceleration control using the target acceleration.

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