Vehicle assistance device for performing collision avoidance operations based on the position and movement condition of a target object

Abstract

A driving assistance device installed in a host vehicle calculates an overlap ratio for a target object positioned in front of the host vehicle within the same lane. This ratio is the ratio of the target object's width to its lateral distance from a lane marking line. The device also determines the object's motion condition (i.e., whether it is stationary, moving in the same direction as or toward the host vehicle, or moving laterally relative to the host vehicle's forward direction). The amount of compensation required to delay or advance the start of a collision avoidance operation by the driving assistance device is determined based on the overlap ratio and / or the target object's motion condition.

Description

BACKGROUND OF THE INVENTIONField of the application

[0001] The present invention relates to a driving assistance device for installation in a motor vehicle for assisting a vehicle driver in avoiding collision with objects such as vehicles traveling ahead. More specifically, the invention relates to a driving assistance device for use in a case where driving is carried out in a lane whose boundaries are defined by a pair of (left-side, right-side) lane marking lines. The term "lane" is used herein in a general sense to refer to a vehicle path defined by a pair of marking lines on the surface of a road, highway, etc. Description of the state of the art

[0002] Techniques for providing driving assistance to assist in preventing collisions with objects located in front of a vehicle (hereinafter referred to as a host vehicle) are known, wherein such objects (hereinafter referred to as target objects) are detected using a radar device, a camera device, etc. installed in the host vehicle, and wherein driving assistance operations are performed based on the detection results.

[0003] For example, with a technique described in JP 3 075 064 B2, when the host vehicle is traveling in a lane and it is detected that a preceding vehicle is encroaching into the lane (that is, is located partially within the lane and partially within an adjacent lane), a relationship called the "preceding vehicle encroachment level" is derived. This is defined as the ratio W / Wo, where Wo is the total width of the preceding vehicle and W is the width of the part of the preceding vehicle that encroaches into the traveling lane of the host vehicle. Driving assistance for assisting the driver of the host vehicle to avoid a collision with the preceding vehicle is performed based on the derived value of the preceding vehicle encroachment level.

[0004] The term "leading object" or "leading vehicle" used herein refers to an object or vehicle that is located in front of a host vehicle and is moving in the same direction as the host vehicle. The term "stationary object" or "stationary vehicle" refers to an object or vehicle that is stationary and located in front of the host vehicle. The term "oncoming object" or "oncoming vehicle" refers to an object or vehicle that is located in front of a host vehicle and is moving in the opposite direction to the host vehicle. Motion of a leading vehicle or object may also have a transverse component (in a direction perpendicular to the forward direction of the host vehicle).

[0005] With the technique described in JP 3 075 064 B2, when the forward vehicle intrusion level is relatively large, the detection distance is increased accordingly. Here, the term "detection distance" refers to the minimum separation distance between the host vehicle and the preceding vehicle at which a driving support operation (e.g., issuing warning signals to the host vehicle driver, braking intervention, etc.) will be initiated. In contrast, when the overlap ratio is relatively small, the detection distance is reduced.

[0006] However, if the detection distance is determined based on the preceding vehicle intrusion level described above, the timing at which a driving support operation is started may not be appropriate. For example, at the time of detection, the preceding vehicle may be moving in a transverse direction to leave the host vehicle's lane, thereby reducing the possibility of a collision. However, in the known technology of JP 3 075 064 B2, in such a case, the detection distance is made large regardless of any transverse movement of the preceding vehicle when the preceding vehicle intrusion level is large. As a result, the driving support operations may be started excessively early and may actually be unnecessary because the preceding vehicle may quickly leave the host vehicle's lane.

[0007] The article by Krook, J. and Larsson, J.: "Extended Adaptive Cruise Control based on multiple target information", Master's thesis, Chalmers University of Technology, Gothenburg, Sweden, 2013, mentions lateral and longitudinal traffic disturbances and that taking their influences into account can lead to an improvement in the response of the ACC.

[0008] DE 10 2012 214 852 A1 discloses a method for selecting objects in an environment of a vehicle, which uses object recognition information regarding the objects, such as the type of the objects. SUMMARY OF THE INVENTION

[0009] The object of the invention is therefore to provide a driving assistance device that appropriately determines the time at which driving assistance operations begin to avoid a collision with a detected target object. This object is achieved with a driving assistance device according to the features of claim 1. The dependent claims relate to preferred developments of the invention.

[0010] The driving assistance device is applicable to a host vehicle equipped with a target object detection device (e.g., radar device) for detecting target objects located in front of the host vehicle and a lane marking line detection device (e.g., camera device) for detecting a pair of lane marking lines that define a lane on which the host vehicle travels.

[0011] The driving assistance device basically includes a target object acquisition section, a lane marking line information acquisition section, an overlap ratio calculation section, a moving condition detection section, and a timing compensation section, the respective functions of which are mainly implemented by a computer upon executing a stored program.

[0012] The target object acquisition section is for acquiring information regarding a target object such as a preceding vehicle (e.g., the position of the object relative to the host vehicle, etc.) based on detection results generated by the target object detection device. The lane marking line information acquisition section is for acquiring information regarding the pair of lane marking lines of the lane in which the host vehicle is traveling based on detection results generated by the lane marking line detection device. The overlap ratio calculation section is for calculating an overlap ratio as the ratio of a lateral distance (distance between one of the lane marking lines and the target object) and the width of the target object.Preferably, respective values ​​of the overlap ratio are calculated with respect to the left-hand and right-hand lane marking lines of the lane. The values ​​of the lateral distance and width are as measured in a direction perpendicular to the forward direction of the host vehicle and as viewed from the host vehicle, respectively, and are obtained based on the lane marking line information and the target object information. The moving condition detection section is for detecting the moving condition of the target object (i.e., whether the object is stationary or moving, and the moving direction) based on the target object information.

[0013] The driving assistance device is characterized by having a timing compensation section that sets a compensation amount based on the overlap ratio calculated by the ratio calculation section and / or the moving condition detected by the moving condition detection section. Here, the term "compensation amount" refers to an amount of adjustment (i.e., advance or retard) applied to the timing of starting a driving assistance operation, the driving assistance operation potentially being performed to avoid a collision between the target object and the host vehicle.

[0014] The use of the "preceding vehicle intrusion level" described above according to the prior art has the disadvantage that (when the preceding vehicle is entirely in the host vehicle's lane, separate from any lane marking line), no information regarding the lateral position of the preceding vehicle in the lane is provided. However, the overlap ratio defined above provides such information. In particular, the ratio indicates the portion of the host vehicle's lane occupied by the preceding vehicle and the position of the occupied portion. This enables more effective application of driving assistance to avoid a collision with the preceding vehicle.

[0015] Furthermore, the probability of a collision with a target object such as a preceding vehicle also depends on the moving condition of the target object, that is, whether it is stationary, moving away, or moving toward the host vehicle. Thus, according to the present invention, the probability of a collision (which determines the compensation amount set by the timing compensation section) is calculated based not only on the overlap ratio but also on the moving condition of the target object. This also enables effective application of driving assistance for avoiding a collision with a target object.

[0016] In addition, the compensation section sets the compensation amount as an amount of delay of the TTC operation timing (time at which a driving support operation for collision avoidance is started) when it is detected that the target object is moving laterally away from the forward direction of the host vehicle (that is, when it is about to move into an adjacent lane).

[0017] According to another aspect, the compensation section of the driving support device is preferably configured to set the compensation amount based on only the calculated value of the overlap ratio when it is determined that the target object is stationary, and to set the compensation amount based on the calculated value of the overlap ratio and the moving condition of the target object when it is determined that the target object is moving.

[0018] Furthermore, the compensation section is preferably configured such that when a plurality of respective different types of driving support operations can be selected to be executed with respect to a detected target object, the compensation amount is also set according to the selected type of driving support operation.

[0019] For example, when the types of driving support operations include issuing warning indications and performing braking, the compensation amount applied in the case of issuing warning indications is preferably made larger than the amount applied in the case of braking.

[0020] Furthermore, the compensation section is preferably configured such that, when it is determined that the target object is a preceding vehicle, the compensation amount is also adjusted according to the type of the preceding vehicle (ie, the size of the preceding vehicle, which is determined based on the vehicle type). For example, the wider the width of a preceding vehicle, the greater the likelihood of a collision with the host vehicle. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram showing the general configuration of an embodiment of a driving support device; Fig. 2 is a flowchart for describing start timing compensation processing executed by the embodiment; Fig. 3A, Fig. 3B and Fig. 4A, Fig. 4B are conceptual diagrams for illustrating positions of vehicles with respect to lane marking lines of a traffic lane; Fig. 5A and Fig. 5B are conceptual diagrams for illustrating values ​​obtained from a lane marking line overlap ratio when a preceding vehicle is adjacent to a left lane marking line and a right lane marking line, respectively; and Fig. 6 shows conceptual diagrams for illustrating moving conditions of a vehicle arranged in front of a host vehicle. DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] An embodiment of a driving assistance device will be described below with reference to the drawings. The embodiment is a PCS (Pre-Crash Safety System) 2 installed on a motor vehicle, hereinafter referred to as a host vehicle. When the PCS 2 determines that there is a danger of a collision between the host vehicle and a detected target object (a preceding vehicle, a stationary object, etc.) located in front of the host vehicle, the PCS 2 performs operations (such as issuing warning signals to the driver of the host vehicle and performing braking intervention) to assist in collision avoidance or to reduce the damage caused if a collision occurs.

[0022] As it is in Fig. 1, the PCS 2 includes a driving assistance device 10, various sensors, and a set of controlled devices (brake actuators, etc.) 30. The sensors shown are a camera device 20, a radar device 22, a yaw rate sensor 24, and a wheel speed sensor 26, but other sensors may also be used. The camera device 20 is an (electronic) stereo camera device that captures images of an area in front of the host vehicle, the image contents being analyzed to obtain target object information concerning objects appearing in the captured images. The information derived for a target object includes the estimated distance of the object from the host vehicle, its direction relative to the host vehicle (i.e., azimuth angle relative to the forward direction of the host vehicle), the type of object, and the shape of the object.The types into which a target object can be classified according to this embodiment include "motor vehicle," "pedestrian," and "neither motor vehicle nor pedestrian." However, other target object classifications, such as "bicycle," "animal," etc., may be used if necessary for a country in which the driving assistance device is used.

[0023] The operation of the PCS 2 is described below assuming that the host vehicle is traveling in a lane whose boundaries are defined by a pair of (left-side and right-side) lane marking lines, typically white in color and formed on the road surface. The camera device 20 is also configured to capture lane marking line information expressing the relative position of the host vehicle with respect to the lane marking lines, the shape of the lane marking lines (i.e., straight or curved), etc.

[0024] The radar device 22 directively transmits electromagnetic waves in the millimeter wavelength band, which are reflected by target objects located in front of the host vehicle. The radar device 22 thereby derives, based on the resulting reflected waves from the target objects, target information expressing the distance, azimuth, and speed of each detected target object relative to the host vehicle. The camera device 20 and the radar device 22 each perform the above-described detection operations at predetermined periodic intervals to update the target information and the lane marking line information.

[0025] The yaw rate sensor 24 may be of a generally used type for detecting the yaw rate of the host vehicle. The wheel speed sensor 26 detects the rotational speed of the road wheels of the host vehicle, and the driving assistance device 10 calculates the traveling speed of the host vehicle based on the road wheel rotational speed. The driving assistance device 10 obtains information regarding the traveling condition of the host vehicle based on the detection signals from the yaw rate sensor 24 and the wheel speed sensor 26.

[0026] The driving assistance device 10 is mainly composed of a conventional microcomputer including a CPU (central processing unit) 12, a ROM (read-only memory) 14, a RAM (random access memory) 16, etc. The CPU 12 performs various processing operations for effective driving assistance according to detection results obtained from the camera device 20, the radar device 22, the yaw rate sensor 24, and the wheel speed sensor 26 by executing a program previously stored in a data storage medium such as the ROM 14. While performing these processing operations, the driving assistance device 10 controls the controlled devices 30 according to the required form of driving assistance.

[0027] The controlled devices 30 include (but are not limited to) actuators that drive the brakes, a steering mechanism, seat belts, etc., a warning signal device, and the like.

[0028] The driving assistance device 10 predicts a TTC (time to collision) as an estimated time that will elapse before a collision occurs between the host vehicle and a detected target object. In the case of multiple detected target objects, respective TTC values ​​are predicted for each target object.

[0029] Based on the TTC estimated for a target object, the driving support device 10 controls the controlled devices 30 to determine the respective TTC operation timings at which various types of driving assistance are started to avoid a collision with the target object, that is, the timings for applying the vehicle brakes, intervening the steering operations performed by the vehicle driver, tightening the seat belts, outputting warning signals directed to the driver, and the like.

[0030] Different compensation amounts (advance or retard) can be applied to the different TTC operating times. Thus, in the following description, the term "TTC operating time compensation" refers to compensation applied to any specific type of driving support operation, such as braking intervention.

[0031] Each TTC operating point (e.g., the start of a braking intervention) is determined based on the relative speed and position of the target object relative to the host vehicle, the type of object, and the host vehicle's driving environment. Information regarding the driving environment can, for example, specify whether the road surface is slippery due to ice or snow.

[0032] The driving assistance device 10 is configured to apply compensation for delaying the TTC operation timing when the reliability of the detection results obtained for the target object by the camera device 20 and the radar device 22 for the target object, etc., is determined to be below a predetermined level. Furthermore, according to this embodiment, the driving assistance device 10 compensates the TTC operation timing based on a lane marking line overlap ratio (described later) and a moving state of the target object. Compensation processing

[0033] Fig. Fig. 2 is a flowchart showing compensation processing performed by the driving support device 10 for compensating a TTC operation timing set with respect to a target object. The processing sequence shown in Fig. 2 is continuously repeated during operation of the driving support device.

[0034] First (step S400), the driving assistance device 10 acquires target object information expressed by detection results obtained from the camera device 20 concerning an object located in front of the host vehicle, that is, information indicating whether the target object is a vehicle or a pedestrian. Lane marking line information expressed by detection results from the camera device 20 concerning the lane marking lines of the lane in which the host vehicle is traveling is also obtained (step S402).

[0035] Based on the target object information and the lane marking line information thus obtained, the driving assistance device 10 then calculates the width W of the target object, the distance (L_L) from the right side of the target object to the left-side lane marking line, and the distance (L_R) from the left side of the target object to the right-side lane marking line from the host vehicle's perspective. The left-side and right-side lane marking line overlap ratios are then calculated using the following equations (1) and (2): Left-hand lane marking line overlap ratio = L_L / W Right-hand lane marking line overlap ratio = L_R / W

[0036] The above is illustrated by the conceptual diagrams of the Fig. 3A, Fig. 3B and Fig. 4A, Fig. 4B, in which the target object is a leading vehicle 110, as viewed by a host vehicle 100 traveling in a lane bounded by left-hand and right-hand lane marking lines 200 and 202.

[0037] As in the example of Fig. As shown in Figure 5A, the left-side lane marking line overlap ratio is equal to 0% when the distance L_L between the left-side lane marking line 200 and the right side of a preceding vehicle 110 is zero (that is, when the preceding vehicle 110 is outside the lane of the host vehicle, but the right side of the preceding vehicle 110 is located above the left-side lane marking line 200). As the distance L_L successively increases (that is, as the preceding vehicle 100 moves transversely toward the right-side lane marking line 202), the left-side lane marking line overlap ratio increases accordingly. Specifically, the value of the left-side lane marking line overlap ratio successively increases to over 100% when the value of L_L increases to greater than the width W of the preceding vehicle 110.

[0038] Similarly, the right-hand lane marking line overlap ratio is 0%, as shown in the example of Fig. 5B, when the distance L_R between the right-hand lane marking line 202 and the left side of a preceding vehicle 110 is zero. As the distance L_R successively increases (as the preceding vehicle 110 moves transversely toward the left-hand lane marking line 200), the right-hand lane marking line overlap ratio increases accordingly. That is, when L_R increases to greater than the width W of the preceding vehicle 110, the right-hand lane marking line overlap ratio successively increases to over 100%.

[0039] According to the present embodiment, the distance L_L between the left-side lane marking line and the right side of the target object is used to express the positional relationship of the target object to the left-side lane marking line. However, it is also possible to appropriately use the distance between the left-side lane marking line and any other predetermined location on the target object, such as the center of the target object, the left side of the target object, etc. Similarly, it is also possible to use the distance between the right-side lane marking line and any other predetermined location on the target object instead of the distance L_R described above.

[0040] In addition, it is possible to use only the right-hand lane marking line overlap ratio or only the left-hand lane marking line overlap ratio, for example, selecting one of these ratios for use according to the lateral position of the target object.

[0041] Following step S404, the driving support device 10 acquires target object information from detection results obtained for the target object by the radar device 22 (step S406), then combines the target object information with the target object information obtained in step S400 from the detection results of the camera device 20 to obtain information, hereinafter referred to as fusion target object information (step S408).

[0042] The driving assistance device 10 then executes processing (step S410) to assign the target object to one of a set of ten categories (1) to (10) described below for use in a branching operation of the subsequent step (S424). The categories are assigned based on the target object information obtained from the camera device 20 and the radar device 22. Of these categories, categories (7) to (9) are assigned to target objects that cannot be detected by the camera device 20 but can only be detected by the radar device 22. The categories are as follows: (1) A leading vehicle (a vehicle located in front of the host vehicle and traveling in the same direction as the host vehicle). (2) A pedestrian positioned in front of the host vehicle and walking in the same direction as the host vehicle. (3) A stationary vehicle located in front of the host vehicle. (4) A stationary pedestrian positioned in front of the host vehicle. (5) An incoming vehicle (a vehicle located in front of the host vehicle and driven towards the host vehicle. (6) An oncoming pedestrian positioned in front of the host vehicle and walking toward the host vehicle. (7) (“Detected by radar only”) A target object located in front of the host vehicle, moving in the same direction as the host vehicle, and detected only by the millimeter-wave radar device. (8) (“Radar only”) A stationary target located in front of the host vehicle and detected only by the millimeter-wave radar device. (9) (“Detected only by radar”) A target object located in front of the host vehicle, moving towards the host vehicle and detected only by the millimeter-wave radar device. (10) A target object that lies outside all categories (1) to (9).

[0043] Thus, the driving support device 10 classifies the target objects according to the three types of moving conditions (i.e., preceding, stationary, or incoming) and according to the type of object (vehicle or pedestrian), with combinations of these types forming a total of 9 categories, to which a category of objects outside these 9 categories is added. The diagrams of the Fig. 6, for example, show examples of a stationary vehicle 120 located in front of a host vehicle 100, a leading vehicle 122, and an oncoming vehicle 124.

[0044] Following step S410, the driving assistance device 10 calculates the lateral movement speed of the target object in step S412 based on a history of consecutive positions obtained by the object up to the current time. Each of these positions is derived from fusion target information calculated during the execution of step S408. When T is referred to as the acquisition time interval of the fusion target information (derived from detection results of the camera device 20 and the radar device 22 as described above) during which six consecutive lateral positions P1-P6 of a target object are obtained, the lateral movement speed of the target object is calculated using the following equation (3): (P4−P1) / 3T+(P5−P2) / 3T+(P6−P3) / 3T / 3

[0045] If it is determined in step S410 that the target object is a stationary object such as the stationary vehicle 120 in Fig. 6, resulting in the result of YES in step S414, it is determined (step S416) whether the lane marking line overlap ratio (calculated for the target object using equations (1) and (2)) satisfies one of the following equations (4) and (5) (that is, is within the range defined by the equations): 150%≤[left-side lane marking line overlap ratio]≤500% AND 0%<[right-side lane marking line overlap ratio]≤100% 150%≤[right-hand lane marking line overlap ratio]≤500% AND 0%<[left-hand lane marking line overlap ratio]≤100%

[0046] If the target object is a stationary object and the lane marking line overlap ratio satisfies either of equations (4) and (5), this indicates that the target object is close to a lane marking line. Specifically, if equation (4) is satisfied, this indicates that the target object is directly adjacent to (or overlaps) the right-hand lane marking line. If equation (5) is satisfied, this indicates that the target object is directly adjacent to (or overlaps) the left-hand lane marking line. In any case, the driving assistance device 10 determines that there is only a low probability of a collision between the host vehicle and the target object.

[0047] However, if the target object is a stationary object and the lane marking line overlap ratio does not satisfy either of equations (4) and (5), this indicates that the target object is separated from both the right-hand and left-hand lane marking lines. Thus, in this case, it is determined that the probability of a collision between the host vehicle and the target object is not low.

[0048] Thus, if neither of equations (4) and (5) is satisfied (NO in step S416), the driving assistance device 10 determines that the target object is not a stationary object for which the TTC operation timing is to be delayed, and thus returns to step S400. If the lane marking line overlap ratio satisfies either of equations (4) and (5) (YES in step S416), the driving assistance device 10 determines that the target object is a stationary object for which the TTC operation timing is to be delayed, and then executes step S424.

[0049] If it is determined that the target object is a mobile object (NO in step S414), the driving support device 10 determines whether the mobile object has been located within the same lane as the host vehicle for a predetermined period of time and is moving in a stable condition without lateral displacement movement (step S418).

[0050] The determination may be such, for example, that if it has been detected that the target object is a preceding vehicle whose lane marking line overlap ratio does not satisfy any of equations (4) and (5) and whose lateral displacement speed is below a predetermined minimum threshold and which has been located in the same lane as the host vehicle for at least a predetermined period of time (extending up to the current time), the result in step S418 will be YES.

[0051] If the result in step S418 is YES, the driving assistance device 10 determines that a collision between the host vehicle and the preceding vehicle can be more easily avoided by advancing the TTC operation timing. Thus, a compensation amount of advancing the TTC operation timing is set (step S420), and then step S428 is executed. Thus, according to this embodiment, the TTC operation timing is advanced only when the target object is a preceding vehicle that has been traveling in the same lane as the host vehicle for at least a predetermined period of time, separated from the respective lane marking lines (i.e., located substantially centrally on the lane) under a stable traveling condition without significant lateral movement.

[0052] If it is determined that the target object is not a preceding vehicle that satisfies these conditions (NO in step S418), the driving support device 10 determines (step S422) whether the lateral movement speed and the lane marking line overlap ratio of the target object satisfy either of the following equations (6) and (7) (that is, are within the ranges defined by the equations). A positive value for the lateral movement speed indicates that the lateral movement of a target object is directed to the right, while a negative value indicates that the lateral movement is directed to the left from the viewpoint of the host vehicle. 150%≤[left-side lane marking line overlap ratio]≤500%AND0%<[right-side lane marking line overlap ratio]≤100%AND[average speed of lateral movement]≥0.5 m / s 150%≤[right-hand lane marking line overlap ratio]≤500%AND 0%<[left-hand lane marking line overlap ratio]≤100%AND[average speed of lateral movement]≥−0.5m / s

[0053] When the target object (mobile object) satisfies equation (6), the driving assistance device 10 determines that the target object is close to the right-side lane marking line and is moving rightward at a lateral movement speed exceeding the predetermined value (ie, 0.5 m / s). When the target object satisfies equation (7), it is determined that the target object is close to the left-side lane marking line and is moving leftward at a lateral movement speed exceeding the predetermined value.

[0054] Since this always indicates that the target object is moving away from the forward direction of the host vehicle, the driving support device 10 determines that the probability of a collision is low. As shown, for example, in Fig. 6, when the preceding vehicle 122 or the oncoming vehicle 124 moves laterally, as indicated by an arrow A, the vehicle moves away from the forward direction of the host vehicle 100.

[0055] If neither of equations (6) and (7) is satisfied for the target object, this indicates that the target object is separated from each of the left and right lane marking lines and is not moving laterally away from the forward direction of the host vehicle at a speed exceeding the predetermined value. In this case, the driving assistance device 10 determines that the probability of a collision between the host vehicle and the target vehicle is not low.

[0056] As shown, for example, by the examples in Fig. As shown in Figure 6, if the leading vehicle 122 or the oncoming vehicle 124 is not moving laterally as indicated by arrow A (away from the forward direction of the host vehicle 100), it may be moving laterally in the direction of arrow B or may soon begin moving in that direction. Thus, there is a likelihood of a collision with the host vehicle 100.

[0057] According to this embodiment, a mobile object subject to detection using equations (6) and (7) may be any preceding object or incoming object moving in the same lane as the host vehicle. However, it is possible to limit the detection to application only to those mobile objects detected as preceding vehicles or incoming vehicles.

[0058] When the lateral movement speed and the lane marking line overlap ratio of the target object (mobile object) do not satisfy any of equations (6) and (7) (NO in step S422), the driving support device 10 determines that the target object is not an object for compensation for delaying the TTC operation timing, and then the processing returns to step S400.

[0059] If the lateral movement speed and the lane marking line overlap ratio of the target object satisfy either of equations (6) and (7) (YES in step S422), or if the target object is stationary and the result of the determination in step S416 described above is YES, step S424 is executed. In step S424, a branch is performed according to the type of target object (as previously determined by the processing in step S410).

[0060] Specifically, when the target object is of any one of types (1) to (9), the driving support device 10 executes step S426 to set a compensation amount for a delay of the TTC operation timing according to this type, and the operation then proceeds to step S428. If the target object is of type (10), the operation proceeds directly to step S428 without setting a compensation amount for the TTC operation timing. If no compensation amount is set for the TTC operation timing, the compensation amount is initialized to zero in step S426.

[0061] When setting a compensation amount of a delay of the TTC operation timing for the target object, the size of the compensation amount is determined using the following relationship: Vehicle > Pedestrian > Stationary Object

[0062] In addition, the size of the compensation amount of the delay is determined according to the moving condition of the target object using the following relationship: preceding (moving) object > incoming (moving) object > stationary object

[0063] When setting a compensation amount of a delay of the TTC operation timing, it is possible to set the compensation amount regardless of the type of driving assistance to be performed (i.e., issuing warning indications, braking intervention, etc.). Alternatively, the compensation amount may be equal to n according to the type of driving assistance to be performed (i.e., when respective different TTC operation timings are applied for the initiation of braking intervention, the initiation of steering intervention, etc.). In the latter case, it is advantageous to set a larger value for a compensation amount of a TTC operation timing delay for issuing a warning indication than for executing braking intervention. For ease of understanding, this description only considers the TTC operation timing for a single type of driving assistance (e.g., braking intervention).

[0064] In step S428, the driving support device 10 applies a degree of retardation or advancement of the TTC operation timing according to the compensation amount set in step S420 or step S426, and the operation then proceeds to step S400.

[0065] According to this embodiment described above, a left-side lane marking line overlap ratio and a right-side lane marking line overlap ratio are derived with respect to a target object, which are the ratio of the distance of the right side of the target object to the left-side lane marking line to the (lateral) width of the target object (as viewed from the host vehicle) and the ratio of the distance of the left side of the target object to the right-side lane marking line to the width of the target object, respectively. Each of these ratios takes values ​​exceeding 100% when the target object is within the host vehicle's lane and separated from each of the left-side and right-side lane marking lines.

[0066] Compensation to advance or delay the TTC operation timing is applied based on the lane marking line overlap ratio values ​​and the moving condition of the target object. Driving assistance to avoid collision with the target object can thus be initiated at an appropriate time.

[0067] In particular, compensation is applied to delay the TTC operation timing when it is detected that the target object is moving laterally away from the forward direction of the host vehicle, since the probability of a collision with a target object is lower under such a moving condition. This can ensure that driving assistance is not executed at an inappropriately early time.

[0068] With reference to the appended claims, a target object information obtaining means in the claims is an example of the driving support apparatus 10 of the above embodiment when executing the processing steps S400 and S406 (in Fig. 2 above) according to the stored program. A lane marking line information acquisition device in the claims is similarly an example of the execution of step S402, a ratio calculation device is similarly an example of the execution of step S404, a moving condition detection device is similarly an example of the execution of step S412, and a timing compensation device is similarly an example of the execution of steps S420 and S426. Further embodiments

[0069] According to the above embodiment, when none of the above equations (4) and (5) is satisfied (in the case where a target object is a stationary object) or when none of the above equations (6) and (7) is satisfied (in the case where a target object is a mobile object), a compensation amount of a delay of the TTC operation timing is set regardless of the values ​​of the left-side and right-side lane marking line overlap ratios obtained for the target object. However, it is also possible to configure the device in such a case such that the compensation amount of a delay of the TTC operation timing is set according to the values ​​of the left-side and right-side lane marking line overlap ratios.For example, the compensation amount of the delay of the TTC operation timing may be increased according to the degree to which the left-side or right-side lane marking line overlap ratio approaches 0%.

[0070] Furthermore, it is possible to configure the apparatus such that when the target object is a mobile object and at least one of equations (6) or (7) is satisfied for the target object, the higher the absolute value of the lateral movement speed of the target object, the larger the compensation amount of the delay of the TTC operation timing is made.

[0071] Furthermore, it is possible to configure the apparatus such that when a target object has been classified as a vehicle belonging to one of the above-described motion categories (i.e., it is a preceding vehicle, a stationary vehicle, or an incoming vehicle), it is further categorized according to the vehicle type, and the compensation amount of the delay of the TTC operation timing is then modified according to the vehicle type.

[0072] For example, if it is determined that the target object is an oncoming vehicle whose type has a high effective braking ability (that is, develops a strong braking force), the compensation amount of the delay of the TTC operation timing can be made larger than in the case of a vehicle type having a lower effective braking ability, because a vehicle having a high effective braking ability can be avoided more easily.

[0073] Similarly, it can be found that a type of vehicle having a small width can be avoided more easily than a vehicle having a large width, and thus the compensation amount of the delay of the TTC operation timing can be made larger in the case of a target object being a vehicle having a small width than in the case of a vehicle having a large width.

[0074] Furthermore, it is possible to configure the driving assistance device such that, when the target object is a preceding vehicle, a vehicle overlap ratio between the preceding vehicle and the host vehicle (for example, the percentage of the width of the preceding vehicle that overlaps the host vehicle) is taken into account when setting the delay compensation amount for the TTC operation timing. That is, the delay compensation amount is made larger when the vehicle overlap ratio is small than when it is large.

[0075] In addition, the compensation amount of deceleration can be made larger when the width of the host vehicle's lane is large than when the width is small.

[0076] Furthermore, it is advantageous to configure the driving support device such that calculation of the left-side and right-side lane marking line overlap ratios is stopped and no delay compensation is applied to the TTC operation timing when the degree of reliability of detection of the lane marking lines by the camera device 20 is estimated to be lower than a predetermined value.

[0077] Furthermore, it is possible to configure the apparatus such that when one of the right-hand and left-hand lane marking lines is not detected, the values ​​used in the calculations of equations (1), (2), and (4) to (7) are obtained using an estimated position of the undetected lane marking line based on tracing that lane marking line up to the point where detection failed.

[0078] It is thus apparent that the invention is not limited to the embodiment described above and various modifications or alternative configurations of the embodiment are possible within the scope indicated in the appended claims.

Claims

[1] A driving assistance device (10) for installation in a host vehicle (100), the host vehicle (100) including a target object information detecting device for detecting target objects located in front of the host vehicle (100) and a lane marking line detecting device for detecting a pair of lane marking lines (200, 202) defining a lane of the host vehicle (100), the driving assistance device (10) comprising: a target object information acquisition device (S400, S406) configured to acquire target object information concerning a target object based on detection results generated by the target object detection device; a lane marking line information acquiring means (S402) configured to acquire lane marking line information concerning the pair of lane marking lines (200, 202) based on detection results generated by the lane marking line detecting device; a ratio calculation device (S404) configured to calculate at least one overlap ratio based on the lane marking line information and the target object information as a ratio of a value of a lateral distance (L_L, L_R) to a value of a width (W) of the target object, each measured in a direction at a right angle to a forward direction of the host vehicle (100) and each viewed from the viewpoint of the host vehicle (100), wherein the lateral distance (L_L, L_R) comprises a distance between the target object and one of the pair of lane marking lines (200, 202); and a movement condition detecting means (S412) configured to detect a movement condition of the target object based on the target object information; characterized by a timing compensation device (S420, S426) configured to set a compensation amount of advance or delay to be applied to a timing of a start of a driving support operation, the driving support operation being potentially executed to avoid a collision between the target object and the host vehicle (100), wherein the compensation amount is based on the overlap ratio calculated by the ratio calculating means (S404) and the movement condition detected by the movement condition detecting means (S412), and wherein the time compensation means (S420, S426) is configured to set the compensation amount as an amount of delay in starting the driving support operation when the moving condition of the target object includes lateral movement of the target object away from the forward direction of the host vehicle (100). [2] Driving assistance device (10) according to claim 1, wherein the time compensation device (S420, S426) is designed to set the compensation amount based only on the calculated value of the overlap ratio when the moving condition of the target object indicates a stationary object; and Set the compensation amount based on the calculated value of the overlap ratio and based on the moving condition of the target object when the moving condition indicates a moving object. [3] The driving assistance device (10) according to claim 1, wherein one or more respective different types of driving assistance operations can be performed with respect to a detected target object, and wherein the time compensation means (S420, S426) is configured to set respective compensation amounts according to the types of the driving assistance operations. [4] The driving support device (10) according to claim 3, wherein the types of driving support operations include outputting warning indications and executing braking, and wherein a compensation amount applied in the case of outputting warning indications is made larger than a compensation amount applied in the case of executing braking. [5] The driving assistance device (10) according to claim 1, wherein the compensation amount is set according to the size of the overlap ratio and the moving condition of the target object. [6] The driving assistance device (10) according to claim 1, wherein the target object information obtaining means (S400, S406) is configured to assign the target object to one of a plurality of predetermined target object categories, and wherein the compensation amount is set according to the assigned target object category. [7] The driving assistance device (10) according to claim 6, wherein the predetermined target object categories include at least a pedestrian category and a vehicle category. [8] The driving assistance device (10) according to claim 7, wherein the target object information acquiring means (S400, S406) is configured to select one of a plurality of predetermined vehicle types as corresponding to the target object when the target object is assigned to the vehicle category, and wherein the compensation amount is set according to the corresponding vehicle type.

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