CROSS REFERENCE TO RELATED APPLICATIONS

This nonprovisional application claims priority to Japanese Patent Application No. 2019-052863 filed with the Japan Patent Office on Mar. 20, 2019, the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to a driving assistance (support) apparatus configured to execute collision avoidance control, when an object present in a travelling direction of a vehicle is detected, in order to avoid a collision between the vehicle and the object.

BACKGROUND

One conventionally known driving assistance apparatus of such a kind which is applied to a vehicle (hereinafter also referred to as the “conventional apparatus”) is equipped with an ultrasonic sonar apparatus as an object detection apparatus. In addition, the conventional apparatus executes the collision avoidance control (specifically, control for generating an alert) when an object in the travelling direction of the vehicle is detected by the ultrasonic sonar apparatus. Furthermore, the conventional apparatus estimates the travelling direction of the vehicle by using a navigation device and enhances detection sensitivity of the ultrasonic sonar apparatus to detect an object which is present in the estimated travelling direction (see, for example, Japanese Patent Application Laid-Open (kokai) No. 2015-121960).

SUMMARY

Incidentally, reliability of the position with respect to a vehicle obtained by an object detection apparatus such as an ultrasonic sonar apparatus may vary depending on a type of object in some cases. Hereinafter, a value indicative of the above-described reliability will be referred to as a “detection certainty value,” or a “certainty value” for simplification.

For example, as for the ultrasonic sonar apparatus, the certainty value concerning a wall of a building detected as an object is generally higher than the certainty value concerning a pedestrian detected as another object. The reason for this is as follows. The ultrasonic sonar apparatus transmits a wave. The transmitted wave are reflected by an object to be a reflection wave. The ultrasonic sonar apparatus receives the reflection wave to detect the object. The strength of the reflection wave from the wall is higher than that of the reflection wave from the pedestrian.

Hereinafter, an object which tends to provide the certainty value which is relatively large will be referred to as a “high certainty object,” and an object which tends to provide the certainty value which is relatively small will be referred to as a “low certainty object.” In addition, an object which needs to be monitored in order to determine whether or not it is necessary to execute the collision avoidance control for that object also referred to as a “monitoring target object.”

If the driving assistance apparatus treats (regards) the low certainty object, as well as the high certainty object, as the monitoring target object, there is a relatively high possibility that the collision avoidance control is erroneously executed for an object which is not present in the travelling direction of the vehicle in actuality. Namely, there is the possibility that unnecessary collision avoidance control (hereinafter also referred to as “unnecessary control”) is executed in this case. Meanwhile, if the driving assistance apparatus treats only the high certainty object as the monitoring target object, there is another relatively high possibility that the collision avoidance control is not executed for an object (in this case, the low certainty object) which is actually present in the travelling direction of the vehicle. However, in the conventional apparatus, it is not considered to appropriately extract the monitoring target object on the basis of the detection certainty value.

In view of the forgoing, one object of the present disclosure is to provide a driving assistance apparatus configured to be able to execute the collision avoidance control for not only the high certainty object but also the low certainty object while avoiding occurrence of the unnecessary control.

A driving assistance apparatus for achieving the above-described object (hereinafter also referred to as the “apparatus of the present disclosure”) comprises a first object detecting sensor device (a sonar apparatus33), a second object detecting sensor device (a front camera31), and a control unit (a PCS-ECU21and an ICS-ECU22). The control unit may be implemented by at least one programmed processor whose operation is determined by a predetermined program, gate arrays and the like.

The first object detecting sensor device detects an object present in a travelling direction of a vehicle (10) as a “first object” (sonar detected object), and obtains a position (a longitudinal position Dsx(c) and a lateral position Dsy(c)), and a “certainty value” (Cv) of the first object such that the certainty value increases as reliability of the obtained position increases.

The control unit is configured to determine whether or not a monitoring target object satisfies a predetermined executing condition on the basis of at least said position obtained by said first object detecting sensor device. The monitoring target object is one of the first objects, and whose certainty value is determined to be higher than a certainty threshold (a first certainty threshold Cth1 and a second certainty threshold Cth2). The control unit is configured to execute collision avoidance control in order to avoid collision between said monitoring target object and said vehicle (step535ofFIG. 5) when it is determined that said monitoring target object satisfies said executing condition.

The second object detecting sensor device detects an object present in the travelling direction as a “second object” (camera detected object), obtains a position (a longitudinal position Dcx(a) and a lateral position Dcy(a)) of the second object and information on a type of the second object. The second object detecting sensor device may determine (or obtain a determination result as to) whether or not a type of the second object is a “specific type” (for example, a “pedestrian”).

Furthermore, the control unit is configured to:obtain determination result as to whether or not the type of the second object is a specific type;determine whether or not the second object is also detected as the first object on the basis of the obtained position of the first object and the obtained position of the second object (a condition (f2));determine whether or not a threshold application condition is satisfied, the threshold application condition including a condition which is satisfied when it is determined that the second object is also detected as the first object and it is determined that the type of the second object is the specific type (a condition (c2));adopt (use) a predetermined first certainty threshold (Cth1) as the certainty threshold (that is, set the certainty threshold to the first certainty threshold) when it is determined that the threshold application condition is not satisfied (a condition (e3)); andadopt (use) a predetermined second certainty threshold (Cth2) which is smaller than the first certainty threshold as the certainty threshold (that is, set the certainty threshold to the second certainty threshold) when it is determined that the threshold application condition is satisfied (a condition (f1)).

The first certainty threshold is set to a value smaller than the certainty value which is obtained when the first object detecting sensor device detects the high certainty object. Meanwhile, second certainty threshold is set to a value smaller than the certainty value which is obtained when the first object detecting sensor device detects the low certainty object. When the second object is a specific kind of the low certainty object (for example, a pedestrian), the type of that second object is determined to be the specific type.

Therefore, if an object which is detected by the first object detecting sensor device is determined to be the low certainty object, the second certainty threshold, which is smaller than the first certainty threshold, is adopted (used) as the certainty threshold. Accordingly, although an object which is present in the travelling direction of the vehicle is the low certainty object, that low certainty object will be treated as the monitoring target object. Meanwhile, when an object which is present in the travelling direction of the vehicle is not the low certainty object, the first certainty threshold is adopted (used) as the certainty threshold, and thus occurrence of the unnecessary control can be avoided appropriately.

In another aspect of the apparatus of the present disclosure, the control unit is configured to determine whether or not said second object has continuously been detected by said second object detecting sensor device for a time period longer than a predetermined time threshold (first duration time threshold Td1) in order to determine whether or not said threshold application condition is satisfied (a condition (c3)).

According to the present aspect, occurrence of the unnecessary control which is caused due to incorrect detection of the second object can be avoided appropriately.

Furthermore, the first object detecting sensor device may comprise a “transmission section” which transmits an electromagnetic wave or a sonic wave as a “transmission wave” to a predetermined object detecting region and a “reception section” which receives a “reflection wave” generated by reflection of the transmission wave at the first object, and may be configured to obtain the certainty value on the basis of at least strength of the reflection wave.

In addition, the second object detecting sensor device may comprise an image obtaining section which obtains (captures) an image of a region in the travelling direction as a “travelling direction image,” and may be configured to determine whether or not the type of the second object is the specific type by using the travelling direction image.

Notably, in the above description, in order to facilitate understanding of the present disclosure, the constituent elements of the disclosure corresponding to those of an embodiment of the disclosure which will be described later are accompanied by parenthesized names and/or symbols which are used in the embodiment; however, the constituent elements of the disclosure are not limited to those in the embodiment defined by the names and/or the symbols. Other objects, other features, and attendant advantages of the present disclosure will be readily appreciated from the following description of the embodiment of the disclosure which is made with reference to the accompanying drawings.

