Drive assist apparatus

The drive assist apparatus detects an object around an own vehicle, and detects a moving direction of the detected object when the detected object is relatively approaching the own vehicle. The drive assist apparatus predicts a movement prediction position to which the object will move, and executes drive assist upon the movement prediction position being a collision prediction position. The collision prediction position is a position where, if the object relatively moves to the movement prediction position, there is a possibility that the object will collide with the own vehicle. The drive assist includes at least one of a task of avoiding a collision between the object and the own vehicle, and a task of mitigating a damage due to the collision. The drive assist apparatus determines an execution timing of the drive assist as a function of the moving direction detected by the moving direction detection means, and the collision prediction position.

TECHNICAL FIELD

The present invention relates to technologies for avoiding a collision between an own vehicle and objects or mitigating damage caused by a collision.

BACKGROUND ART

A known technology predicts a position where an own vehicle and an object, which is measured by sensors, such as a camera and/or a radar, around the own vehicle would collide with each other, thus performing drive assist of the own vehicle. The drive assist is to avoid a collision between the own vehicle and the object or mitigate damage due to a collision. Such a technology is disclosed in, for example, patent document 1.

A drive assist apparatus, which performs such drive assist, for example calculates a time to collision (TTC) with an object based on a relative speed of the object relative to a vehicle and a distance between the vehicle and the object. The TTC represents a time until which the vehicle would collide with the object. Then, the drive assist apparatus performs the drive assist when the TTC, which has been decreasing as the vehicle has been approaching the object, reaches one of activation thresholds previously determined for the respective types of drive assist including automatic braking and automatic steering.

CITATION LIST

Patent Document

SUMMARY OF INVENTION

Technical Problem

The predicted position, i.e. predicted collision position, where the vehicle and an object would collide with each other changes as the moving direction of the object relative to the vehicle changes. For this reason, if the predicted collision position of the object with respect to the vehicle changes, the probabilities of the object colliding with the vehicle at the respective predicted collision positions may differ from each other.

Unfortunately, the conventional technology including the technology of document 1 sets the activation thresholds independently of the moving direction of the object relative to the vehicle. This results in the same activation threshold being set for each of the different predicted collision positions where the corresponding collision possibilities are different from each other. This may result in the conventional technology having a difficulty in performing the drive assist at proper timings determined for the respective collision possibilities.

In order to solve such a problem, the present invention provides technologies, each of which is capable of performing drive assist at proper timings determined for respective collision possibilities between an object and a vehicle.

Means for Solving Problem

A drive assist apparatus according to an exemplary aspect of the present invention includes an object detection unit, a moving direction detection unit, a position prediction unit, a drive assist unit, and a determination unit.

The object detection unit detects an object around an own vehicle, and the moving direction detection unit detects a moving direction of the object detected by the object detection unit when the object is relatively approaching the own vehicle. The position prediction unit predicts a movement prediction position to which the object detected by the object detection unit will move.

The drive assist unit executes drive assist upon the movement prediction position predicted by the position prediction unit being a collision prediction position. The collision prediction position is a position where, if the object relatively moves to the movement prediction position, there is a probability that the object will collide with the own vehicle. The drive assist includes at least one of a task of avoiding a collision between the object and the own vehicle, and a task of mitigating a damage due to the collision.

The determination unit determines an execution timing of the drive assist by the drive assist unit as a function of the moving direction detected by the moving direction detection unit, and the collision prediction position.

This configuration enables the drive assist to be executed at a an execution timing determined based on the moving direction of the object, which is relatively approaching the own vehicle, and the collision probability at the collision prediction position between the object and the own vehicle; the execution timing is properly determined depending on the collision probability at the collision prediction position.

The probability of the object moving toward the far-side of the end of the own vehicle through the front side of the own vehicle in its travelling direction is likely to be higher than the probability of the object moving to the near-side of the end of the own vehicle from the position deviated from the front side of the own vehicle in its travelling direction.

Upon the collision prediction position being located at a front of the own vehicle in the travelling direction, the determination unit of the drive assist apparatus according to the exemplary aspect can be configured to make the execution timing at which the collision prediction position is located at the far-side of the front end of the own vehicle in the moving direction earlier than the execution timing at which the collision prediction position is located at the near-side of the front end of the own vehicle in the moving direction.

This configuration enables the execution timing of the drive assist at a collision prediction position where there is a higher probability of the object colliding with the own vehicle to be earlier than the execution timing of the drive assist at another collision prediction position where there is a lower probability of the object colliding with the own vehicle.

Note that bracketed reference numerals in the claims represent correspondence relationship with respect to specific means described in the following embodiments as an example, and therefore do not restrict the scope of the present invention.

DESCRIPTION OF EMBODIMENT

The following describes the embodiments of the present invention with reference to the accompanying drawings.

First Embodiment

Structure

FIG. 1illustrates a precrash safety system2, which is an example of drive assist systems according to the first embodiment of the first embodiment of the present invention. The precrash safety system (PCS)2, which is installed in a vehicle100, performs a drive assist task to output warning and/or activate brakes if there is a probability, i.e. a possibility, that an object would collide with the own vehicle100. The drive assist task is to avoid a collision between the own vehicle100and the object, or to mitigate damage due to a collision.

The PCS2includes a drive assist apparatus10, various sensors SS, and controlled targets30. The PCS2includes, for example, a camera sensor20, a radar sensor22, a yaw rate sensor24, and wheel speed sensors26as the various sensors SS.

The camera sensor20is configured as a stereo camera capable of detecting the distances to objects. The camera sensor20repeatedly captures a predetermined range around the vehicle100, for example, the front region of the vehicle100, in a predetermined cycle. Then, the camera sensor20detects, based on the captured images, object information about an object included in the captured images; the object information includes, for example, the type, shape, distance relative to the own vehicle100, and angle with respect to the own vehicle100. The camera sensor20can classify the types of objects into vehicles, pedestrians, and the other objects.

The radar sensor22repeatedly scans a predetermined range in front of the vehicle100with directional electromagnetic waves, such as millimeter waves, and receives echoes, i.e. reflection waves, from an object based on the scanned electromagnetic waves, thus detecting object information of the object, which includes, for example, the distance of the object relative to the own vehicle100and the relative speed of the object relative to the own vehicle100.

Specifically, each of the camera sensor20and the radar sensor22detects an object in front of the own vehicle100in a corresponding one of the predetermined cycles.

The yaw rate sensor24is designed as a known yaw rate sensor for measuring the yaw angular velocity, i.e. the raw rate, of the own vehicle100. Each of the wheel speed sensors26detects, based on the rotational speed of the corresponding wheel of the own vehicle100, the speed of the own vehicle100. The drive assist apparatus10obtains travelling information of the own vehicle100based on the yaw rate detected by the yaw rate sensor24and the vehicle speed detected by the wheel speed sensors26.

The drive assist apparatus10is mainly comprised of a known microcomputer equipped with a CPU12, a ROM14, a RAM16, and other devices. The CPU12runs programs stored in the ROM14based on measurement results of various sensors SS, so that the drive assist apparatus10performs various tasks.

The drive assist apparatus10activates, based on the measurement results, i.e. measurement information, which are obtained from the various sensors SS, the controlled targets30for drive assist. The controlled targets30include, for example, actuators for driving, for example, the brakes, the steering, and the seatbelts, and a warning device that outputs a warning.

The drive assist apparatus10calculates, for each object detected by the camera sensor20and/or radar sensor22, a TTC based on the relative speed of the object relative to the own vehicle100, and the distance between the own vehicle100and the object.

If the object and the own vehicle100approach each other so that the TTC falls down to one of predetermined activation thresholds, the drive assist apparatus10controls, according to a type of drive assist, at least one of the controlled targets30corresponding to the type of drive assist for avoiding a collision between the vehicle100and the object or mitigating damage due to a collision. This control of the at least one of the controlled targets30carries out one or more drive assist tasks, such as a task of outputting a warning, a task of activating the brakes, a task of assisting the operation of the steering, and winding the seat belts.

That is, an activation threshold for the TTC determines the execution timing of the drive assist. The larger an activation threshold for the TTC is, the earlier the execution timing of the drive assist is, and the smaller an activation threshold for the TTC is, the later the execution timing of the drive assist is.

The activation thresholds for the drive assist are individually determined as TTC maps M(TCC) for the respective types of the drive assist as a function of

(1) The relative approach speed of an object to the own vehicle100

(2) The relative position of the object relative to the own vehicle100

(3) The type of the object

(4) The travelling environment around the own vehicle100

(5) The reliabilities of the measurement results of the camera sensor20and the radar sensor22.

The TTC maps M(TCC), which include the determined activation thresholds for the respective types of the drive assist are, are stored beforehand in, for example, the ROM14or the RAM16.

Referring toFIG. 1, the TTC maps M(TCC) are stored in the ROM14. The travelling environment around the own vehicle100represents, for example, whether the road surface is slippery due to snow on the road surface or the freeze of the road surface. One of the sensors SS is configured to measure the information about the travelling environment, and to send the information about the travelling environment to the drive assist apparatus10.

For example, the drive assist apparatus10according to the first embodiment is configured to delay the execution timing of each type of the drive assist upon the reliability of object measurement being lower as compared with the execution timing of the corresponding type of the drive assist upon the reliability of object measurement being higher.

Routine

The following describes a drive assist routine carried out by the drive assist apparatus10, i.e. its CPU12, with reference to the flowchart ofFIG. 2.

The flowchart illustrated inFIG. 2shows the drive assist routine for setting the activation thresholds for drive assist. The flowchart is executed each time one scan of electromagnetic waves by the radar sensor22is completed.

Note that the operations in steps S400to D418carried out by the drive assist apparatus10, i.e. its CPU12described later respectively constitute functional elements, and therefore, the operations in steps S400to D418can be represented as functional blocks S400to S418that the drive assist apparatus10includes.

When running the drive assist routine, the drive assist apparatus10detects plural objects around the own vehicle100, especially in front of the own vehicle100, in accordance with received signals of echoes and images captured by the camera sensor20in step S400; the echoes are obtained based on scanning of electromagnetic waves by the radar sensor22. In step S400, the drive assist apparatus10calculates, as the relative position of each of the detected objects relative to the own vehicle100, the distance between the own vehicle100and a corresponding one of the detected objects and the direction of a corresponding one of the detected objects relative to the own vehicle100.

The drive assist apparatus10calculates the relative speed of at least one object that is approaching the own vehicle100based on change of the relative position of each object relative to the own vehicle100in step S400. The drive assist apparatus10also calculates the relative lateral speed and the relative approach speed of the at least one object as a function of the relative speed of the at least one object approaching the own vehicle100and the direction of the at least one object from the own vehicle100in step S400. The relative lateral speed of the at least one object is comprised of a component of the relative speed of the at least one object relative to the own vehicle100in the lateral direction corresponding to the width direction of the own vehicle100. The relative approach speed is comprised of a component of the relative speed in the front direction of the own object100.

Note that the operation of the drive assist apparatus10in step S400corresponds to, for example, object detection means.

The drive assist apparatus10serves as, for example, a position prediction unit to determine whether the detected at least one object, which will be referred to as a target object, is approaching the own vehicle100in step S402.

In step S404, the drive assist apparatus10serves as, for example, the position prediction unit upon determining that the target object is approaching the own vehicle100(YES in step S402) to

(1) Calculate the TTC of the target object to the own vehicle100as a function of the distance and relative speed of the target object relative to the own vehicle100

(2) Predict the position, which will be referred to as a movement prediction position, to which the target object will move in accordance with the trajectory of the relative speed of the target object (seeFIG. 3).

In step S404, the drive assist apparatus10obtains the movement prediction position as a collision prediction position upon determining that, if the target object relatively moves to the movement prediction position, there is a possibility that the target object will collide with the own vehicle100.

Following the operation in step S404, the drive assist apparatus10determines whether the direction of the relative lateral movement of the target vehicle is the rightward direction or the leftward direction from the driver of the own vehicle100in step S406.

Upon determining that the direction of the relative lateral movement of the target vehicle is the rightward direction relative to the driver of the own vehicle100(YES in step S406), the drive assist apparatus10serves as, for example, a determination unit to determine the activation threshold if the target object relatively moves in the rightward direction to collide with the front of the own vehicle100in its travelling direction in step S408.

For example, in step S408, the drive assist apparatus10determines the type of the drive assist tasks in accordance with, for example, the relative approach speed of the target object, the relative position of the target object, the type of the target object, the travelling environment around the own vehicle100, and the reliabilities of the measurement results of the target object by the camera sensor20and the radar sensor22. Then, in step S408, the drive assist apparatus10reads, from the TTC map M(TTC) corresponding to the determined drive assist task, a value of the activation threshold; the value of the activation threshold matches with the calculated TTC.

Then, in step S408, the drive assist apparatus10determines a final value of the activation threshold based on the readout value of the activation threshold, the relative lateral moving direction, i.e. rightward direction, of the target object relatively approaching the own vehicle100, and the collision prediction position. The task of determining the activation threshold will be described in detail later.

Otherwise, upon determining that the direction of the relative lateral movement of the target vehicle is the leftward direction relative to the driver of the own vehicle100(NO in step S406), the drive assist apparatus10determines whether the direction of the relative lateral movement of the target vehicle is the leftward direction or the leftward direction from the driver of the own vehicle100in step S410.

Upon determining that the direction of the relative lateral movement of the target vehicle is the leftward direction from the driver of the own vehicle100(YES in step S410), the drive assist apparatus10serves as, for example, the setting unit to set the activation threshold if the target object relatively moves in the leftward direction to collide with the front of the own vehicle100in its travelling direction in step S412.

For example, in step S412, the drive assist apparatus10determines the type of the drive assist tasks in accordance with, for example, the relative approach speed of the target object, the relative position of the target object, the type of the target object, the travelling environment around the own vehicle100, and the reliabilities of the measurement results of the target object by the camera sensor20and the radar sensor22. Then, in step S412, the drive assist apparatus10reads, from the TTC map M(TTC) corresponding to the determined drive assist task, a value of the activation threshold; the value of the activation threshold matches with the calculated TTC.

Then, in step S412, the drive assist apparatus10determines a final value of the activation threshold based on the readout value of the activation threshold, the relative lateral moving direction, i.e. leftward direction, of the target object relatively approaching the own vehicle100, and the collision prediction position. The task of determining the activation threshold will be described in detail later.

Additionally, upon determining that the direction of the relative lateral movement of the target vehicle is neither the rightward direction nor the leftward direction from the driver of the own vehicle100(NO in step S406), the drive assist apparatus10determines that the target object is relatively moving to the own vehicle100in its front direction. Then, the drive assist apparatus10serves as, for example, the setting unit to set the activation threshold if the target object relatively moves from the front direction of the own vehicle100to collide with the own vehicle100in step S414.

For example, in step S414, the drive assist apparatus10determines the type of the drive assist tasks in accordance with, for example, the relative approach speed of the target object, the relative position of the target object, the type of the target object, the travelling environment around the own vehicle100, and the reliabilities of the measurement results of the target object by the camera sensor20and the radar sensor22. Then, in step S414, the drive assist apparatus10reads, from the TTC map M(TTC) corresponding to the determined drive assist task, a value of the activation threshold; the value of the activation threshold matches with the calculated TTC.

Then, in step S414, the drive assist apparatus10determines a final value of the activation threshold based on the readout value of the activation threshold, the relative lateral moving direction, i.e. front direction, of the target object relatively approaching the own vehicle100, and the collision prediction position. The task of determining the activation threshold will be described in detail later.

The drive assist apparatus10, which has completed the operation in step S408, S412, or S414, determines whether the TTC is reaching the final value of the activation threshold determined in any one of the operations in steps S408, S412, and S414in step S416.

Upon determining that the TTC has just reached the final value of the activation threshold determined in any one of the operations in steps S408, S412, and S414(YES in step S416), the drive assist apparatus10serves as, for example, a drive assist unit to control at least one of the controlled targets30, which is required to perform the determine type of the drive assist tasks, thus performing the determined type of the drive assist tasks in step S418.

The following describes how the drive assist apparatus10determines the activation threshold in each of steps S408, S412, and S414.

Movement of Target Object in Rightward Direction

Referring toFIG. 4, if the relative lateral moving direction of the target object is the rightward direction, and the target object is approaching the own vehicle100toward the far-side corner of the front end, i.e. the right front end, of the own vehicle100, the target vehicle is approaching the own vehicle100while passing through the front side of the own vehicle100in its travelling direction.

In contrast, if the relative lateral moving direction of the target object is the rightward direction, and the target object is approaching the own vehicle100toward the near-side corner of the front end, i.e. the left front end, of the own vehicle100, the target vehicle is approaching the own vehicle100from the position deviated from the front side of the own vehicle100in its travelling direction.

If the relative lateral moving direction of the target object is the rightward direction, the first case where the target object is approaching the own vehicle100toward the far-side corner of the front end, i.e. the right front end, of the own vehicle100has a higher probability of colliding with the own vehicle100than the second case where the target object is approaching the own vehicle100toward the near-side corner of the front end, i.e. the left front end, of the own vehicle100.

If the relative lateral moving direction of the target object is the rightward direction, the drive assist apparatus10according to the first embodiment therefore determines that a value of the activation threshold in the first case where the target object is approaching the own vehicle100toward the far-side corner of the front end, i.e. the right front end, of the own vehicle100is greater than a value of the activation threshold in the second case where the target object is approaching the own vehicle100toward the near-side corner of the front end, i.e. the left front end, of the own vehicle100(seeFIG. 5). Note that a map illustrated inFIG. 5is stored in, for example, the ROM14or RAM16while having a format readable by the CPU12of the drive assist apparatus10.

If the relative lateral moving direction of the target object is the rightward direction, this results in the execution timing of the drive assist in the first case where the collision prediction position is located at the far-side of the end of the own vehicle100in the moving direction of the target object being earlier than the execution timing of the drive assist in the second case where the collision prediction position is located at the near-side of the end of the own vehicle100in the moving direction of the target object.

In the case where the relative lateral moving direction of the target object is the rightward direction, and the target object is approaching the own vehicle100toward the outside of the far-side corner of the own vehicle100, the target object will not collide with the own vehicle100if the target object moves toward the outside of the far-side corner of the front end of the own vehicle100without any change.

However, if the absolute velocity of the target object and/or the own vehicle100changes, or the absolute moving direction of the target object and/or the own vehicle100changes, so that the relative speed and/or the relative moving direction of the target object relative to the own vehicle100changes, there will be a possibility of the target object colliding with the own vehicle100.

In contrast, in the case where the relative lateral moving direction of the target object is the rightward direction, and the target object is approaching the own vehicle100toward the outside of the near-side edge of the own vehicle100, the target object will unlikely collide with the own vehicle100even if the absolute velocity of the target object and/or the own vehicle100changes, or the absolute moving direction of the target object and/or the own vehicle100changes, so that the relative speed and/or the relative moving direction of the target object relative to the own vehicle100changes.

Accordingly, as illustrated inFIGS. 4 and 5, in the case where the relative lateral moving direction of the target object is the rightward direction, the range where the activation threshold should be set is expanded as an expanded range (d) to cover the outside of the far-side edge of the own vehicle100in the moving direction of the target object. This enables, in the case where the relative lateral moving direction of the target object is the rightward direction, drive assist to be carried out even if the collision prediction position is located outside of the far-side edge of the own vehicle100in the moving direction of the target object.

As illustrated inFIG. 5, in the case where the relative lateral moving direction of the target object is the rightward direction, the activation threshold gradually increases from the near-side front end of the own vehicle100to the center portion, i.e. the center portion of the front end of the own vehicle100, keeps constant from the center of the front end of the own vehicle100to a portion that has passed through the far-side edge of the front end of the own vehicle100, and thereafter gradually decreases toward the end edge of the expanded range (d). That is, a value of the activation threshold when the center of the front end of the own vehicle100is the collision prediction position is greater than a value of the activation threshold when the collision prediction position is located at one of the lateral edges of the front end of the own vehicle100, to which the activation threshold is set, in its travelling direction.

Movement of Target Object in Leftward Direction

Like the relative lateral moving direction of the target object being the rightward direction, if the relative lateral moving direction of the target object is the leftward direction, the first case where the target object is approaching the own vehicle100toward the far-side corner of the front end, i.e. the left front end, of the own vehicle100has a higher probability of colliding with the own vehicle100than the second case where the target object is approaching the own vehicle100toward the near-side corner of the front end, i.e. the right front end, of the own vehicle100.

If the relative lateral moving direction of the target object is the leftward direction, the drive assist apparatus10according to the first embodiment therefore determines that a value of the activation threshold in the first case where the target object is approaching the own vehicle100toward the far-side corner of the front end of the own vehicle100is greater than a value of the activation threshold in the second case where the target object is approaching the own vehicle100toward the near-side corner of the front end of the own vehicle100(seeFIG. 7). Note that a map illustrated inFIG. 5is stored in, for example, the ROM14or RAM16while having a format readable by the CPU12of the drive assist apparatus10.

If the relative lateral moving direction of the target object is the leftward direction, this results in the execution timing of the drive assist in the first case where the collision prediction position is located at the far-side of the end of the own vehicle100in the moving direction of the target object being earlier than the execution timing of the drive assist in the second case where the collision prediction position is located at the near-side of the end of the own vehicle100in the moving direction of the target object.

As illustrated inFIGS. 6 and 7, in the case where the relative lateral moving direction of the target object is the leftward direction, the range where the activation threshold should be set is expanded as an expanded range (d) to cover the outside of the far-side edge of the own vehicle100in the moving direction of the target object. This enables, in the case where the relative lateral moving direction of the target object is the leftward direction, drive assist to be carried out even if the collision prediction position is located outside of the far-side edge of the own vehicle100in the moving direction of the target object.

As illustrated inFIG. 7, in the case where the relative lateral moving direction of the target object is the leftward direction, the activation threshold gradually increases from the near-side of the front end of the own vehicle100to the center portion, i.e. the center portion of the front end of the own vehicle100, keeps constant from the center of the front end of the own vehicle100to a portion that has passed through the far-side of the front end of the own vehicle100, and thereafter gradually decreases toward the end edge of the expanded range (d). That is, a value of the activation threshold when the center of the front end of the own vehicle100is the collision prediction position is greater than a value of the activation threshold when the collision prediction position is located at one of the lateral edges of the front end of the own vehicle100, to which the activation threshold is set, in its travelling direction.

Movement of Target Object in Longitudinal Direction

The following describes a case where the target object is approaching the own vehicle100in the longitudinal direction of the own vehicle100. In this case, as compared with the approaching direction is the rightward direction or leftward direction described above, there is little deviation between

(1) The probability of the target object colliding with the own vehicle100at a collision prediction position

(2) The probability of the target object colliding with the own vehicle100at another collision prediction position.

This results in the activation threshold for drive assist being set to the common value independently of the collision prediction positions.

The relationship between the collision prediction position and the activation threshold if the target object is moving in each of the right and leftward directions relative to the own vehicle100so as to approach the own vehicle100is not expressed as the configuration illustrated in a corresponding one ofFIGS. 5 and 7, but as a stepped configuration illustrated inFIG. 8. The map illustrated inFIG. 8is stored in, for example, the ROM14or RAM16while having a format readable by the CPU12of the drive assist apparatus10.

The faster the relative approach speed of the target object that is approaching the own vehicle100in the face-to-face direction is, the greater the damage caused by a collision between the target object and the own vehicle100will be. Thus, as illustrated inFIG. 9, the drive assist apparatus10can be configured such that, the faster the relative approach speed of the target object relative to the own vehicle100is, the greater the activation threshold is independently of the collision prediction position. Similarly, the drive assist apparatus10can be configured such that, the higher the yaw rate of the own vehicle100is, the greater the activation threshold is independently of the collision prediction position. Note that the map illustrated inFIG. 9is stored in, for example, the ROM14or RAM16while having a format readable by the CPU12of the drive assist apparatus10.

In a case where the target object is approaching the own vehicle100toward the outside of the far-side edge of the own vehicle100, the faster the relative lateral speed of the target vehicle is, the higher the probability of the target object colliding with the own vehicle100due to change of the relative speed or the relative moving direction of the target object relative to the own vehicle100is. Thus, the faster the relative lateral speed of the target object is, the wider the expanded range of the activation threshold, which covers the outside of the far-side edge of the own vehicle100in the moving direction of the target object, can be.

Advantageous Effect

The above described first embodiment achieves the following advantageous effects.

The drive assist apparatus10according to the first embodiment determines the activation threshold for drive assist as a function of the lateral moving direction of a target object relatively approaching the own vehicle100and a collision prediction position. This configuration achieves the first advantageous effect that enables drive assist to be carried out at an execution timing being properly determined depending on the collision probability at the collision prediction position.

The drive assist apparatus10is configured to, when the target object is relatively approaching the own vehicle100, expand the determined range of the activation threshold to the outside of the far-side edge of the front end of the own vehicle100in the moving direction of the target object. This configuration enables, even if the target object will collide with the own vehicle100outside the width of the own vehicle100, drive assist to be carried out based on the activation threshold.

Second Embodiment

Structure

The drive assist apparatus10according to the second embodiment is configured to determine, as a function of a collision probability between a target object and the own vehicle100, the activation threshold if the target object will collide with one side of the own vehicle100.

Referring toFIG. 10, if the target object is relatively moving from the front direction of the own vehicle100to approach the own vehicle100, so the collision prediction position is located at the right side or left side of the own vehicle100, the collision probability between the target object and the own vehicle100is likely to be higher at the front end of the own vehicle100in its travelling direction than the collision probability between the target object and the own vehicle100at the rear end of the own vehicle100in its traveling direction.

Accordingly, referring toFIG. 11, the drive assist apparatus10is configured to determine the activation threshold such that the activation threshold increases as the collision prediction position changes from the rear end of the own vehicle100to the front end of the own vehicle100in the travelling direction. This configuration enables the activation timing of drive assist at the front end of the own vehicle100in the travelling direction to be earlier than the activation timing of drive assist at the rear end of the own vehicle100in the travelling direction. Note that a map illustrated inFIG. 11is stored in, for example, the ROM14or RAM16while having a format readable by the CPU12of the drive assist apparatus10.

Note that descriptions of the other configuration will be omitted, because the other configuration is identical to the corresponding configuration of the drive assist apparatus10according to the first embodiment.

Advantageous Effect

Even if the collision prediction position between the target object and the own vehicle100is located at one side of the own vehicle100, the drive assist apparatus10according to the second embodiment is configured to determine the activation threshold as a function of the moving direction of the target object relatively approaching the own vehicle100and the collision prediction position. This configuration enables drive assist to be carried out at a proper timing determined based on a collision probability at the collision prediction position.

Other Embodiments

The drive assist apparatus10according to each of the first and second embodiments includes the TTC maps M(TTC) for the respective types of drive assist. The TTC maps M(TTC) can also be provided for the destinations of the drive assist apparatus10to be used, such as regions or countries of the drive assist apparatus10to be used. The TTC maps M(TTC) can further be provided for the types or sizes of vehicles in which the drive assist apparatus10is to be installed. This enables the drive assist apparatus10to accept at least one of a specified destination of the drive assist apparatus10and specified type and size of the vehicle in which the drive assist apparatus10is to be installed, and to select at least one of the TTC maps M(TTC), which matches with the at least one of the specified destination of the drive assist apparatus10and the specified type and size of the vehicle in which the drive assist apparatus10is to be installed.

This enables an aspect of the drive assist apparatus10to carry out drive assist at a proper timing determined based on the destination of the drive assist apparatus10and/or the type of the vehicle in which the drive assist apparatus10is to be installed.

For example, the drive assist apparatus10according to the first embodiment is configured to determine the activation threshold as a function of the information illustrated inFIGS. 4 to 9in a case where the travelling direction of the own vehicle100is the forward travel direction, but the present invention is not limited to the configuration. Specifically, the drive assist apparatus10can be configured to determine, if the own vehicle100is travelling in the rearward direction, the activation threshold based on the collision probability at the collision prediction position between the target object and the own vehicle100using the information illustrated inFIGS. 4 to 9as long as the rearward direction is regarded as the travelling direction of the own vehicle100. The drive assist apparatus10according to the second embodiment can also be configured to determine, if the own vehicle100is travelling in the rearward direction, the activation threshold based on the collision probability at the collision prediction position between the target object and the own vehicle100using the information illustrated inFIGS. 10 and 11as long as the rearward direction is regarded as the travelling direction of the own vehicle100.

The functions of one element in each of the first and second embodiments can be distributed as plural elements, and the functions that plural elements have can be combined into one element. At least part of the structure of each of the first and second embodiments can be replaced with a known structure having the same function as the at least part of the structure of the corresponding embodiment. A part of the structure of each of the first and second embodiments can be eliminated. At least part of the structure of each of the first and second embodiments can be added to or replaced with the structures of the other embodiment. All aspects included in the technological ideas specified by the language employed by the claims constitute embodiments of the present invention.

The present invention can be implemented by various embodiments in addition to the drive assist apparatuses; the various embodiments include drive assist systems each including one of the above drive assist apparatuses, programs for serving a computer as each of the drive assist apparatuses, storage media storing the programs, and drive assist methods.