Patent Description:
There is known a vehicle collision avoidance assistance device configured to perform collision avoidance braking and collision avoidance steering to avoid a collision between a driver's vehicle and an object ahead of the driver's vehicle. The collision avoidance braking is a collision avoidance process for avoiding a collision between the driver's vehicle and an object by forcibly applying a braking force to the driver's vehicle even if the driver of the driver's vehicle does not operate a brake pedal. The collision avoidance steering is a collision avoidance process for avoiding a collision between the driver's vehicle and an object by forcibly steering the driver's vehicle even if a steering wheel is not operated in the driver's vehicle.

As such a vehicle collision avoidance assistance device, there is known a vehicle collision avoidance assistance device configured to start collision avoidance braking when determination is made that the driver's vehicle may collide with an object ahead of the driver's vehicle, and start collision avoidance steering when determination is made that the collision between the driver's vehicle and the object ahead of the driver's vehicle is still unavoidable (see, for example, <CIT> (<CIT>)). <CIT> discloses a collision avoidance apparatus which suppresses the occurrence of a situation in which the own vehicle veers into an opposing lane to avoid a collision. <CIT> discloses a collision avoidance support device that supports a driver so that a host vehicle avoids a collision with an obstacle. <CIT>discloses a vehicle control apparatus which can prevent an own vehicle from exhibiting unstable behavior when collision avoidance control for avoiding a collision between the own vehicle and an object located ahead of the own vehicle is executed.

The vehicle collision avoidance assistance device described above starts the collision avoidance braking instead of the collision avoidance steering when determination is made that the driver's vehicle may collide with an object ahead of the driver's vehicle regardless of a situation around the driver's vehicle. Depending on the situation around the driver's vehicle, however, the collision between the driver's vehicle and the object may be avoided more appropriately by starting the collision avoidance steering instead of the collision avoidance braking.

The present invention provides a vehicle collision avoidance assistance device capable of performing an appropriate collision avoidance process depending on a situation around a driver's vehicle.

A first aspect of the present invention relates to a vehicle collision avoidance assistance device including a processor. The processor is configured to perform forced braking or forced steering when a driver's vehicle has a possibility of colliding with an object ahead of the driver's vehicle. The forced braking is braking for avoiding a collision between the driver's vehicle and the object by applying a braking force to the driver's vehicle to stop the driver's vehicle before the driver's vehicle collides with the object. The forced steering is steering for avoiding the collision between the driver's vehicle and the object by steering the driver's vehicle to pass by a side of the object. The processor is configured to acquire at least one of information related to a condition of the driver's vehicle and information related to a situation around the driver's vehicle, and determine, based on the acquired information, whether a request condition for requesting execution of the forced steering is satisfied and whether a forbiddance condition for forbidding the execution of the forced steering is satisfied. The processor is configured to perform, when the request condition is not satisfied, the forced braking regardless of whether the forbiddance condition is satisfied, perform the forced steering when the forbiddance condition is not satisfied and the request condition is satisfied, and perform, when the forbiddance condition is satisfied, the forced braking though the request condition is satisfied.

According to the first aspect, determination is made as to whether the request condition is satisfied and whether the forbiddance condition is satisfied in consideration of the condition of the driver's vehicle or the situation around the driver's vehicle. When the request condition is not satisfied, the forced braking is performed regardless of whether the forbiddance condition is satisfied. When the forbiddance condition is not satisfied and the request condition is satisfied, the forced steering is performed. When the forbiddance condition is satisfied, the forced braking is performed though the request condition is satisfied. Therefore, in a scene in which the execution of the forced steering is preferable such that the request condition is satisfied, the forced steering is performed except for a situation in which non-execution of the forced steering is preferable such that the forbiddance condition is satisfied. Thus, an appropriate collision avoidance process can be performed depending on the situation around the driver's vehicle.

The processor is configured to determine that the request condition is satisfied when the processor determines that the braking device deteriorates based on the deterioration status of the braking device, or when the processor determines that a weight of the driver's vehicle is equal to or larger than a predetermined weight, and determine that the request condition is not satisfied when the processor determines that the braking device does not deteriorate based on the deterioration status of the braking device, or when the processor determines that the weight of the driver's vehicle is smaller than the predetermined weight.

In the first aspect, the processor may be configured to acquire a deterioration status of a braking device configured to apply the braking force to the driver's vehicle as the information related to the condition of the driver's vehicle.

The deterioration status of the braking device is an effective index for determining whether the execution of the forced steering instead of the forced braking is preferable. According to the configuration described above, the processor determines whether the request condition is satisfied in consideration of the deterioration status of the braking device. Thus, a more appropriate collision avoidance process can be performed depending on the situation around the driver's vehicle.

In the first aspect, the processor may be configured to acquire a deterioration status of a brake pad of a braking device configured to apply the braking force to the driver's vehicle as the information related to the condition of the driver's vehicle, determine that the request condition is satisfied when the processor determines that the brake pad deteriorates based on the deterioration status of the brake pad, and determine that the request condition is not satisfied when the processor determines that the brake pad does not deteriorate based on the deterioration status of the brake pad.

The deterioration status of the brake pad is an effective index for determining whether the execution of the forced steering instead of the forced braking is preferable. According to the configuration described above, the processor determines whether the request condition is satisfied in consideration of the deterioration status of the brake pad. Thus, a more appropriate collision avoidance process can be performed depending on the situation around the driver's vehicle.

In the first aspect, the processor may be configured to acquire a deterioration status of brake oil for operating a braking device configured to apply the braking force to the driver's vehicle as the information related to the condition of the driver's vehicle, determine that the request condition is satisfied when the processor determines that the brake oil deteriorates based on the deterioration status of the brake oil, and determine that the request condition is not satisfied when the processor determines that the brake oil does not deteriorate based on the deterioration status of the brake oil.

The deterioration status of the brake oil is an effective index for determining whether the execution of the forced steering instead of the forced braking is preferable. According to the configuration described above, the processor determines whether the request condition is satisfied in consideration of the deterioration status of the brake oil. Thus, a more appropriate collision avoidance process can be performed depending on the situation around the driver's vehicle.

In the first aspect, the processor may be configured to control an operation of a braking device configured to apply the braking force to the driver's vehicle such that the braking device to applies a braking force to the driver's vehicle based on an operation amount of a brake pedal of the driver's vehicle, acquire a deceleration of the driver's vehicle as the information related to the condition of the driver's vehicle when the brake pedal is operated by a driver of the driver's vehicle, determine that the request condition is satisfied when the deceleration is equal to or lower than a reference deceleration set based on the operation amount of the brake pedal operated by the driver, and determine that the request condition is not satisfied when the deceleration is higher than the reference deceleration.

The relationship between the operation amount of the brake pedal operated by the driver and the deceleration of the driver's vehicle at that time is an effective index for determining whether the execution of the forced steering instead of the forced braking is preferable. According to the configuration described above, the processor determines whether the request condition is satisfied in consideration of the relationship between the operation amount of the brake pedal operated by the driver and the deceleration of the driver's vehicle at that time. Thus, a more appropriate collision avoidance process can be performed depending on the situation around the driver's vehicle.

In the first aspect, the processor may be configured to acquire a vehicle speed of the driver's vehicle and a gradient of a road surface where the driver's vehicle is traveling. The processor may be configured not to acquire the deceleration of the driver's vehicle when the vehicle speed is lower than a reference vehicle speed or the gradient is larger than a reference gradient.

When the vehicle speed of the driver's vehicle is low or the gradient of the road surface where the driver's vehicle is traveling is large, there is a possibility that the deceleration of the driver's vehicle cannot be acquired accurately. According to the configuration described above, the deceleration of the driver's vehicle is not acquired when the vehicle speed of the driver's vehicle is lower than the reference vehicle speed or the gradient of the road surface where the driver's vehicle is traveling is larger than the reference gradient. Therefore, it is possible to acquire only an accurate deceleration of the driver's vehicle.

In the first aspect, the processor may be configured to acquire a weight of the driver's vehicle as the information related to the condition of the driver's vehicle.

Since the weight of the driver's vehicle affects the deceleration of the driver's vehicle when the driver's vehicle is braked, the weight of the driver's vehicle is an effective index for determining whether the execution of the forced steering instead of the forced braking is preferable. According to the configuration described above, determination is made as to whether the request condition is satisfied in consideration of the weight of the driver's vehicle. Thus, a more appropriate collision avoidance process can be performed depending on the situation around the driver's vehicle.

In the first aspect, the processor may be configured to acquire the number of occupants of the driver's vehicle as the information related to the condition of the driver's vehicle, determine that the request condition is satisfied when the number of occupants is equal to or larger than a predetermined number, and determine that the request condition is not satisfied when the number of occupants is smaller than the predetermined number.

Since the weight of the driver's vehicle affects the deceleration of the driver's vehicle when the driver's vehicle is braked as described above, the weight of the driver's vehicle is an effective index for determining whether the execution of the forced steering instead of the forced braking is preferable. The weight of the driver's vehicle changes depending on the number of occupants of the driver's vehicle. According to the configuration described above, determination is made as to whether the request condition is satisfied in consideration of the number of occupants of the driver's vehicle. Thus, a more appropriate collision avoidance process can be performed depending on the situation around the driver's vehicle.

In the first aspect, the processor may be configured to acquire a pressure in a master cylinder of a braking device as the information related to the condition of the driver's vehicle. The braking device may be configured to apply the braking force to the driver's vehicle. The processor may be configured to determine that the request condition is satisfied when the pressure in the master cylinder is equal to or lower than a predetermined pressure, and determine that the request condition is not satisfied when the pressure in the master cylinder is higher than the predetermined pressure.

The pressure in the master cylinder is an effective index for determining whether the execution of the forced steering instead of the forced braking is preferable. According to the configuration described above, determination is made as to whether the request condition is satisfied in consideration of the pressure in the master cylinder. Thus, a more appropriate collision avoidance process can be performed depending on the situation around the driver's vehicle.

In the first aspect, the processor may be configured to determine whether a succeeding moving object moving behind the driver's vehicle in the same direction as a traveling direction of the driver's vehicle has a collision possibility of colliding with the driver's vehicle under an assumption that the forced braking is performed, acquire, as the information related to the situation around the driver's vehicle, a result of determination as to whether the succeeding moving object has the collision possibility, determine that the request condition is satisfied when the processor determines that the succeeding moving object has the possibility of colliding with the driver's vehicle, and determine that the request condition is not satisfied when the processor determines that the succeeding moving object does not have the possibility of colliding with the driver's vehicle.

Whether the succeeding moving object collides with the driver's vehicle when the forced braking is performed is an effective index for determining whether the execution of the forced steering instead of the forced braking is preferable. According to the configuration described above, determination is made as to whether the request condition is satisfied in consideration of whether the succeeding moving object collides with the driver's vehicle when the forced braking is performed. Thus, a more appropriate collision avoidance process can be performed depending on the situation around the driver's vehicle.

In the first aspect, the processor may be configured to acquire a position of the succeeding moving object, determine that the succeeding moving object has the collision possibility when the processor determines that the succeeding moving object is present within a range of a predetermined distance from the driver's vehicle based on the position of the succeeding moving object, and determine that the succeeding moving object does not have the collision possibility when the processor determines that the succeeding moving object is not present within the range of the predetermined distance from the driver's vehicle based on the position of the succeeding moving object.

The position of the succeeding moving object is an effective index for accurately determining whether the succeeding moving object collides with the driver's vehicle when the forced braking is performed. According to the configuration described above, determination is made by using the position of the succeeding moving object as to whether the succeeding moving object collides with the driver's vehicle when the forced braking is performed. Thus, a more appropriate collision avoidance process can be performed depending on the situation around the driver's vehicle.

In the first aspect, the processor may be configured to acquire a predicted traveling area of the driver's vehicle, acquire a position of the succeeding moving object and a predicted moving area of the succeeding moving object, determine that the succeeding moving object has the collision possibility when the processor determines that the predicted moving area and the predicted traveling area overlap each other and the succeeding moving object is present within a range of a predetermined distance from the driver's vehicle based on the position of the succeeding moving object, determine that the succeeding moving object does not have the collision possibility when the processor determines that the predicted moving area and the predicted traveling area overlap each other and the succeeding moving object is not present within the range of the predetermined distance from the driver's vehicle based on the position of the succeeding moving object, and determine that the succeeding moving object does not have the collision possibility regardless of whether the succeeding moving object is present within the range of the predetermined distance from the driver's vehicle when the processor determines that the predicted moving area and the predicted traveling area do not overlap each other.

Not only the position of the succeeding moving object but also the information on whether the predicted moving area and the predicted traveling area overlap each other is an effective index for accurately determining whether the succeeding moving object collides with the driver's vehicle when the forced braking is performed. According to the configuration described above, by using not only the position of the succeeding moving object but also the information on whether the predicted moving area and the predicted traveling area overlap each other, the processor determines whether the succeeding moving object collides with the driver's vehicle when the forced braking is performed. Thus, a more appropriate collision avoidance process can be performed depending on the situation around the driver's vehicle.

In the first aspect, the processor may be configured to acquire a gradient of a road surface where the driver's vehicle is traveling as the information related to the situation around the driver's vehicle, determine that the request condition is satisfied when the gradient is smaller than zero and an absolute value of the gradient is equal to or larger than a first gradient, and determine that the request condition is not satisfied when the gradient is equal to or larger than zero, or when the absolute value of the gradient is smaller than the first gradient and the gradient is smaller than zero.

The gradient of the road surface where the driver's vehicle is traveling is an effective index for determining whether the execution of the forced steering instead of the forced braking is preferable. According to the configuration described above, the processor determines whether the request condition is satisfied in consideration of the gradient of the road surface where the driver's vehicle is traveling. Thus, a more appropriate collision avoidance process can be performed depending on the situation around the driver's vehicle.

In the first aspect, the processor may be configured to acquire a gradient of a road surface where the driver's vehicle is traveling and a friction coefficient of the road surface as the information related to the situation around the driver's vehicle, and determine that the request condition is satisfied when the friction coefficient is equal to or smaller than a predetermined friction coefficient, the gradient is smaller than zero, and an absolute value of the gradient is equal to or larger than a first gradient. The processor may be configured to determine that the request condition is not satisfied when the friction coefficient is equal to or smaller than the predetermined friction coefficient and the gradient is equal to or larger than zero, or when the absolute value of the gradient is smaller than the first gradient and the gradient is smaller than zero. The processor may be configured to determine that the request condition is satisfied when the friction coefficient is larger than the predetermined friction coefficient, the gradient is smaller than zero, the absolute value of the gradient is equal to or larger than the first gradient, and the absolute value of the gradient is equal to or smaller than a second gradient that is larger than the first gradient. The processor may be configured to determine that the request condition is not satisfied when the friction coefficient is larger than the predetermined friction coefficient and the gradient is equal to or larger than zero, or when the gradient is smaller than zero and the absolute value of the gradient is smaller than the first gradient or larger than the second gradient.

The friction coefficient of the road surface where the driver's vehicle is traveling is an effective index for determining whether non-execution of the forced steering is preferable. According to the configuration described above, the processor determines whether the request condition is satisfied in consideration of the gradient and the friction coefficient of the road surface where the driver's vehicle is traveling. Thus, a more appropriate collision avoidance process can be performed depending on the situation around the driver's vehicle.

The processor may be configured to acquire a cant of a road surface where the driver's vehicle is traveling as the information related to the situation around the driver's vehicle, determine that the forbiddance condition is satisfied when the cant is equal to or larger than a predetermined cant, and determine that the forbiddance condition is not satisfied when the cant is smaller than the predetermined cant.

The cant of the road surface where the driver's vehicle is traveling is an effective index for determining whether non-execution of the forced steering is preferable. According to the configuration described above, the processor determines whether the forbiddance condition is satisfied in consideration of the cant of the road surface where the driver's vehicle is traveling. Thus, a more appropriate collision avoidance process can be performed depending on the situation around the driver's vehicle.

The processor may be configured to acquire, as the information related to the condition of the driver's vehicle, information on whether vehicle stability control for adjusting a driving force or a braking force applied to the driver's vehicle is performed to stabilize traveling behavior of the driver's vehicle, determine that the forbiddance condition is satisfied when the vehicle stability control is performed, and determine that the forbiddance condition is not satisfied when the vehicle stability control is not performed.

Whether the vehicle stability control is performed is an effective index for determining whether non-execution of the forced steering is preferable. According to the configuration described above, the processor determines whether the forbiddance condition is satisfied in consideration of whether the vehicle stability control is performed. Thus, a more appropriate collision avoidance process can be performed depending on the situation around the driver's vehicle.

A vehicle collision avoidance assistance device according to an embodiment of the present invention will be described below with reference to the drawings. As illustrated in <FIG>, a vehicle collision avoidance assistance device <NUM> according to the embodiment of the present invention is mounted on a driver's vehicle <NUM>.

The vehicle collision avoidance assistance device <NUM> includes an ECU <NUM>. The term "ECU" is an abbreviation of "electronic control unit". The ECU <NUM> includes a microcomputer as a main component. The microcomputer includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a non-volatile memory, and an interface. The CPU executes instructions, programs, or routines stored in the ROM to implement various functions.

The driver's vehicle <NUM> includes a drive device <NUM>, a braking device <NUM>, and a steering device <NUM>.

The drive device <NUM> outputs a drive torque TQ_D (driving force) to be applied to the driver's vehicle <NUM> to cause the driver's vehicle <NUM> to travel, and is typified by an internal combustion engine or a motor. The drive device <NUM> is electrically connected to the ECU <NUM>. The ECU <NUM> can control the drive torque TQ_D to be output from the drive device <NUM> by controlling an operation of the drive device <NUM>.

The braking device <NUM> outputs a braking torque TQ_B (braking force) to be applied to the driver's vehicle <NUM> to brake the driver's vehicle <NUM>, and is typified by a brake. The braking device <NUM> is electrically connected to the ECU <NUM>. The ECU <NUM> can control the braking torque TQ_B to be output from the braking device <NUM> by controlling an operation of the braking device <NUM>.

The steering device <NUM> outputs a steering torque TQs (steering force) to be applied to the driver's vehicle <NUM> to steer the driver's vehicle <NUM>, and is typified by a power steering device. The steering device <NUM> is electrically connected to the ECU <NUM>. The ECU <NUM> can control the steering torque TQs to be output from the steering device <NUM> by controlling an operation of the steering device <NUM>.

The driver's vehicle <NUM> further includes an accelerator pedal <NUM>, an accelerator pedal operation amount sensor <NUM>, a brake pedal <NUM>, a brake pedal operation amount sensor <NUM>, a steering wheel <NUM>, a steering shaft <NUM>, a steering angle sensor <NUM>, a steering torque sensor <NUM>, a braking device status detection device <NUM>, a vehicle motion amount detection device <NUM>, a peripheral information detection device <NUM>, and a seating sensor <NUM>.

The accelerator pedal operation amount sensor <NUM> detects an operation amount of the accelerator pedal <NUM>. The accelerator pedal operation amount sensor <NUM> is electrically connected to the ECU <NUM>. The accelerator pedal operation amount sensor <NUM> transmits information on the detected operation amount of the accelerator pedal <NUM> to the ECU <NUM>. The ECU <NUM> acquires the operation amount of the accelerator pedal <NUM> as an accelerator pedal operation amount AP based on the information.

The ECU <NUM> acquires a requested drive torque TQ_D_req (requested driving force) by calculation based on the accelerator pedal operation amount AP and a vehicle speed V100 of the driver's vehicle <NUM>. The requested drive torque TQ_D_req is a drive torque TQ_D to be output from the drive device <NUM> by request. The ECU <NUM> controls the operation of the drive device <NUM> to output the requested drive torque TQ_D_req.

The brake pedal operation amount sensor <NUM> detects an operation amount of the brake pedal <NUM>. The brake pedal operation amount sensor <NUM> is electrically connected to the ECU <NUM>. The brake pedal operation amount sensor <NUM> transmits information on the detected operation amount of the brake pedal <NUM> to the ECU <NUM>. The ECU <NUM> acquires the operation amount of the brake pedal <NUM> as a brake pedal operation amount BP based on the information.

The ECU <NUM> acquires a requested braking torque TQ_B_req (requested braking force) by calculation based on the brake pedal operation amount BP. The requested braking torque TQ_B_req is a braking torque TQ_B to be output from the braking device <NUM> by request. The ECU <NUM> controls the operation of the braking device <NUM> to output the requested braking torque TQ_B_req.

The steering angle sensor <NUM> detects a rotation angle of the steering shaft <NUM> with respect to a neutral position. The steering angle sensor <NUM> is electrically connected to the ECU <NUM>. The steering angle sensor <NUM> transmits information on the detected rotation angle of the steering shaft <NUM> to the ECU <NUM>. The ECU <NUM> acquires the rotation angle of the steering shaft <NUM> as a steering angle θ steer based on the information.

The steering torque sensor <NUM> detects a torque input to the steering shaft <NUM> by the driver via the steering wheel <NUM>. The steering torque sensor <NUM> is electrically connected to the ECU <NUM>. The steering torque sensor <NUM> transmits information on the detected torque to the ECU <NUM>. The ECU <NUM> acquires the torque input to the steering shaft <NUM> by the driver via the steering wheel <NUM> (driver input torque TQs_driver) based on the information.

The braking device status detection device <NUM> detects a status of the braking device <NUM>, and includes a master cylinder pressure sensor <NUM> in this example.

The master cylinder pressure sensor <NUM> detects a pressure in a master cylinder of the braking device <NUM>. The master cylinder pressure sensor <NUM> is electrically connected to the ECU <NUM>. The master cylinder pressure sensor <NUM> transmits information on the detected pressure in the master cylinder to the ECU <NUM>. The ECU <NUM> acquires the pressure in the master cylinder (master cylinder pressure Pm) based on the information.

The vehicle motion amount detection device <NUM> detects a motion amount of the driver's vehicle <NUM>, and includes a vehicle speed detection device <NUM>, a longitudinal acceleration sensor <NUM>, a lateral acceleration sensor <NUM>, and a yaw rate sensor <NUM> in this example.

The vehicle speed detection device <NUM> detects a vehicle speed of the driver's vehicle <NUM>, and is typified by a wheel speed sensor. The vehicle speed detection device <NUM> is electrically connected to the ECU <NUM>. The vehicle speed detection device <NUM> transmits information on the detected vehicle speed of the driver's vehicle <NUM> to the ECU <NUM>. The ECU <NUM> acquires the vehicle speed V <NUM> of the driver's vehicle <NUM> based on the information.

The ECU <NUM> acquires a requested steering torque TQs_req by calculation based on the acquired steering angle θ steer, the acquired driver input torque TQs_driver, and the acquired vehicle speed V100. The requested steering torque TQs_req is a steering torque TQs to be output from the steering device <NUM> by request. The ECU <NUM> controls the operation of the steering device <NUM> to output the requested steering torque TQs_req from the steering device <NUM>. When performing forced steering described later, the ECU <NUM> determines as appropriate a steering torque TQs required to cause the driver's vehicle <NUM> to travel along a target avoidance path Rtgt as the requested steering torque TQs_req regardless of the steering angle θ steer or the like. Then, the ECU <NUM> controls the operation of the steering device <NUM> to output the requested steering torque TQs_req.

The longitudinal acceleration sensor <NUM> detects an acceleration of the driver's vehicle <NUM> in a fore-and-aft direction. The longitudinal acceleration sensor <NUM> is electrically connected to the ECU <NUM>. The longitudinal acceleration sensor <NUM> transmits information on the detected acceleration to the ECU <NUM>. The ECU <NUM> acquires the acceleration of the driver's vehicle <NUM> in the fore-and-aft direction as a longitudinal acceleration Gx based on the information.

The lateral acceleration sensor <NUM> detects an acceleration of the driver's vehicle <NUM> in a lateral direction (width direction). The lateral acceleration sensor <NUM> is electrically connected to the ECU <NUM>. The lateral acceleration sensor <NUM> transmits information on the detected acceleration to the ECU <NUM>. The ECU <NUM> acquires the acceleration of the driver's vehicle <NUM> in the lateral direction as a lateral acceleration Gy based on the information.

The yaw rate sensor <NUM> detects a yaw rate YR of the driver's vehicle <NUM>. The yaw rate sensor <NUM> is electrically connected to the ECU <NUM>. The yaw rate sensor <NUM> transmits information on the detected yaw rate YR to the ECU <NUM>. The ECU <NUM> acquires the yaw rate YR of the driver's vehicle <NUM> based on the information.

The peripheral information detection device <NUM> detects information around the driver's vehicle <NUM>, and includes a radio wave sensor <NUM> and an image sensor <NUM> in this example. Examples of the radio wave sensor <NUM> include a radar sensor (such as a millimeter wave radar). Examples of the image sensor <NUM> include a camera. The peripheral information detection device <NUM> may include an acoustic wave sensor such as an ultrasonic sensor (clearance sonar) or an optical sensor such as a laser radar (light detection and ranging (LiDAR)).

The radio wave sensor <NUM> is electrically connected to the ECU <NUM>. The radio wave sensor <NUM> emits a radio wave, and receives the radio wave reflected by an object (reflected wave). The radio wave sensor <NUM> transmits information (detection result) related to the emitted radio wave and the received radio wave (reflected wave) to the ECU <NUM>. In other words, the radio wave sensor <NUM> detects an object present around the driver's vehicle <NUM>, and transmits information (detection result) related to the detected object to the ECU <NUM>. The ECU <NUM> can acquire information related to the object present around the driver's vehicle <NUM> (object information I_O) based on the information (radio wave information.

In this example, the object is a vehicle, a motorcycle, a bicycle, a person, or the like.

The image sensor <NUM> is electrically connected to the ECU <NUM>. The image sensor <NUM> captures an image around the driver's vehicle <NUM>, and transmits information related to the captured image to the ECU <NUM>. The ECU <NUM> can acquire information related to the periphery of the driver's vehicle <NUM> (peripheral detection information Idct) based on the information (image information I_C).

When an object (forward object 200F) is present ahead of the driver's vehicle <NUM> as illustrated in <FIG>, the ECU <NUM> detects the forward object 200F based on the peripheral detection information Idct. The forward object 200F is a vehicle, a motorcycle, a bicycle, a person, or the like. In the example illustrated in <FIG>, the forward object 200F is a vehicle.

When the ECU <NUM> detects the forward obj ect 200F, the ECU <NUM> can acquire, for example, "a distance between the forward object 200F and the driver's vehicle <NUM> (object distance D200)" and "a speed of the driver's vehicle <NUM> relative to the forward object 200F (relative speed ΔV200)" based on the peripheral detection information Idct.

When an object moving behind the driver's vehicle <NUM> to follow the driver's vehicle <NUM> in the same direction as a traveling direction of the driver's vehicle <NUM> (succeeding moving object <NUM>) is present as illustrated in <FIG>, the ECU <NUM> detects the succeeding moving object <NUM> based on the peripheral detection information Idct. The succeeding moving object <NUM> is a vehicle, a motorcycle, a bicycle, a person, or the like. In the example illustrated in <FIG>, the succeeding moving object <NUM> is a vehicle.

When the ECU <NUM> detects the succeeding moving object <NUM>, the ECU <NUM> can acquire, for example, "a distance between the succeeding moving object <NUM> and the driver's vehicle <NUM> (object distance D300)" and "a speed of the succeeding moving object <NUM> relative to the driver's vehicle <NUM> (relative speed ΔV300)" based on the peripheral detection information Idct.

The ECU <NUM> recognizes "a right lane marking line LM_R and a left lane marking line LM_L defining a traveling lane (driver's vehicle lane LN) of the driver's vehicle <NUM>" based on the peripheral detection information Idct. The ECU <NUM> can determine a range of the driver's vehicle lane LN based on the recognized right and left lane marking lines LM (that is, the right lane marking line LM_R and the left lane marking line LM_L).

The seating sensor <NUM> detects an occupant sitting on a seat of the driver's vehicle <NUM>, and is mounted on the driver's vehicle <NUM> in association with each seat. The seating sensor <NUM> is electrically connected to the ECU <NUM>. When the seating sensor <NUM> detects the occupant sitting on the seat, the seating sensor <NUM> transmits, to the ECU <NUM>, a signal indicating that the occupant is sitting on the seat. The ECU <NUM> acquires the number of occupants of the driver's vehicle <NUM> based on the signal.

Next, an outline of an operation of the vehicle collision avoidance assistance device <NUM> will be described. The vehicle collision avoidance assistance device <NUM> is configured to execute forced braking or forced steering when the driver's vehicle <NUM> may collide with an object ahead of the driver's vehicle <NUM> (forward object).

When the forward object 200F (in an example illustrated in <FIG>, a vehicle stopped ahead of the driver's vehicle <NUM>) is present as illustrated in <FIG>, the forced braking is performed to avoid the collision between the driver's vehicle <NUM> and the forward object 200F by applying a braking force to the driver's vehicle <NUM> to stop the driver's vehicle <NUM> before the driver's vehicle <NUM> collides with the forward object 200F as illustrated in <FIG>. The forced braking is terminated when the driver's vehicle <NUM> is stopped behind the forward object 200F.

When the forward object 200F ahead of the driver's vehicle <NUM> (in an example illustrated in <FIG>, a vehicle stopped ahead of the driver's vehicle <NUM>) is present as illustrated in <FIG>, the forced steering is performed to avoid the collision between the driver's vehicle <NUM> and the forward object 200F by steering the driver's vehicle <NUM> as illustrated in <FIG> to pass by the side of the forward object 200F as illustrated in <FIG>. The forced steering is terminated when the driver's vehicle <NUM> passes by the side of the forward object 200F.

The vehicle collision avoidance assistance device <NUM> acquires information related to conditions of the driver's vehicle <NUM> (driver's vehicle information I_100) and information related to a situation around the driver's vehicle <NUM> (driver's vehicle peripheral information I_S), and determines whether a condition for requesting execution of forced steering (request condition Creq) is satisfied and whether a condition for forbidding the execution of forced steering (forbiddance condition Cfbd) is satisfied based on the driver's vehicle information I_100 and the driver's vehicle peripheral information I_S.

The vehicle collision avoidance assistance device <NUM> may acquire the driver's vehicle information I_100 or the driver's vehicle peripheral information I_S, and determine whether the request condition Creq is satisfied and whether the forbiddance condition Cfbd is satisfied based on the acquired driver's vehicle information I_100 or the acquired driver's vehicle peripheral information I_S.

The vehicle collision avoidance assistance device <NUM> acquires a deterioration status of the braking device <NUM> as the driver's vehicle information I_100 while the driver's vehicle <NUM> is traveling, and determines whether the request condition Creq is satisfied based on the deterioration status of the braking device <NUM>.

The deterioration status of the braking device <NUM> can be grasped by grasping the braking performance of the braking device <NUM>. The braking performance of the braking device <NUM> can be grasped by grasping a relationship between a brake pedal operation amount BP and a braking force thus applied to the driver's vehicle <NUM> from the braking device <NUM>. The braking force applied to the driver's vehicle <NUM> from the braking device <NUM> appears as a deceleration of the driver's vehicle <NUM> (that is, a negative longitudinal acceleration Gx; hereinafter referred to as "deceleration GD").

To accurately acquire the deterioration status of the braking device <NUM>, the vehicle collision avoidance assistance device <NUM> first determines whether the vehicle speed V100 of the driver's vehicle <NUM> is equal to or higher than a predetermined vehicle speed (reference vehicle speed or lower limit vehicle speed Vlimit) and the absolute value of a road surface gradient GR is equal to or smaller than a predetermined gradient (reference gradient or upper limit gradient GRlimit) (that is, whether a braking performance determination condition is satisfied).

When the braking performance determination condition is satisfied, the vehicle collision avoidance assistance device <NUM> determines whether the brake pedal operation amount BP is equal to or larger than a predetermined brake pedal operation amount BPth.

When the vehicle collision avoidance assistance device <NUM> determines that the brake pedal operation amount BP is equal to or larger than the predetermined brake pedal operation amount BPth, the vehicle collision avoidance assistance device <NUM> acquires the deceleration GD of the driver's vehicle <NUM> at that time as the driver's vehicle information I_100, and determines whether the absolute value of the deceleration GD is equal to or smaller than a predetermined deceleration (reference deceleration GDbase) set based on the brake pedal operation amount BP. The reference deceleration GDbase is set to a deceleration that is expected to be generated in the driver's vehicle <NUM> based on the brake pedal operation amount BP when the braking device <NUM> has sufficient braking performance.

When the vehicle collision avoidance assistance device <NUM> determines that the absolute value of the deceleration GD of the driver's vehicle <NUM> is equal to or smaller than the reference deceleration GDbase, the vehicle collision avoidance assistance device <NUM> may determine that the request condition Creq due to the braking performance (first request condition Creq_1) is satisfied. In this example, however, the vehicle collision avoidance assistance device <NUM> increases, by a predetermined value, an index value indicating a possibility that the first request condition Creq_1 is satisfied (braking performance index value). When the vehicle collision avoidance assistance device <NUM> determines that the absolute value of the deceleration GD of the driver's vehicle <NUM> is larger than the reference deceleration GDbase, the vehicle collision avoidance assistance device <NUM> may determine that the first request condition Creq_1 is not satisfied. In this example, however, the vehicle collision avoidance assistance device <NUM> reduces the braking performance index value by a predetermined value.

The vehicle collision avoidance assistance device <NUM> employs a braking performance counter Cbrake as the braking performance index value. When the vehicle collision avoidance assistance device <NUM> determines that the absolute value of the deceleration GD of the driver's vehicle <NUM> is equal to or smaller than the reference deceleration GDbase, the vehicle collision avoidance assistance device <NUM> increments the braking performance counter Cbrake. When the vehicle collision avoidance assistance device <NUM> determines that the absolute value of the deceleration GD of the driver's vehicle <NUM> is larger than the reference deceleration GDbase, the vehicle collision avoidance assistance device <NUM> decrements the braking performance counter Cbrake.

The vehicle collision avoidance assistance device <NUM> determines that the first request condition Creq_1 is not satisfied when the braking performance counter Cbrake is smaller than a predetermined value Cbrake_th, and determines that the first request condition Creq_1 is satisfied when the braking performance counter Cbrake reaches the predetermined value Cbrake_th.

When a brake pad used in the braking device <NUM> deteriorates, the braking performance of the braking device <NUM> decreases, and as a result, the deceleration GD of the driver's vehicle <NUM> decreases. Therefore, the determination as to whether the first request condition Creq_1 is satisfied based on the deceleration GD of the driver's vehicle <NUM> corresponds to the determination as to whether the first request condition Creq_1 is satisfied based on the deterioration status of the brake pad that is acquired as the driver's vehicle information I_100.

Also when brake oil used in the braking device <NUM> deteriorates, the braking performance of the braking device <NUM> decreases, and as a result, the deceleration GD of the driver's vehicle <NUM> decreases. Therefore, the determination as to whether the first request condition Creq_1 is satisfied based on the deceleration GD of the driver's vehicle <NUM> corresponds to the determination as to whether the first request condition Creq_1 is satisfied based on the deterioration status of the brake oil that is acquired as the driver's vehicle information I_100.

When the weight of the driver's vehicle <NUM> including an occupant increases, the deceleration GD of the driver's vehicle <NUM> decreases even if the braking performance of the braking device <NUM> does not decrease. Therefore, the determination as to whether the first request condition Creq_1 is satisfied based on the deceleration GD of the driver's vehicle <NUM> corresponds to the determination as to whether the first request condition Creq_1 is satisfied based on whether the weight of the driver's vehicle <NUM> including an occupant that is acquired as the driver's vehicle information I_100 is equal to or larger than a predetermined weight.

When the weight of the driver's vehicle <NUM> including an occupant increases as described above, the deceleration GD of the driver's vehicle <NUM> decreases even if the braking performance of the braking device <NUM> does not decrease. That is, when the number of occupants in the driver's vehicle <NUM> increases, the deceleration GD of the driver's vehicle <NUM> decreases even if the braking performance of the braking device <NUM> does not decrease. Therefore, the vehicle collision avoidance assistance device <NUM> may acquire the number of occupants of the driver's vehicle <NUM> as the driver's vehicle information I_100, determine that the request condition Creq is satisfied when the acquired number of occupants is equal to or larger than a predetermined number, and determine that the request condition Creq is not satisfied when the acquired number of occupants is smaller than the predetermined number. Master Cylinder Pressure.

When an abnormality occurs in the master cylinder, the master cylinder pressure Pm decreases, and as a result, the braking performance of the braking device <NUM> decreases. Therefore, the vehicle collision avoidance assistance device <NUM> acquires the master cylinder pressure Pm as the driver's vehicle information I_100, and determines whether the master cylinder pressure Pm is equal to or lower than a predetermined pressure Pm_th.

When the vehicle collision avoidance assistance device <NUM> determines that the master cylinder pressure Pm is equal to or lower than the predetermined pressure Pm_th, the vehicle collision avoidance assistance device <NUM> determines that the request condition Creq due to the braking performance (second request condition Creq_2) is satisfied. When the vehicle collision avoidance assistance device <NUM> determines that the master cylinder pressure Pm is higher than the predetermined pressure Pm_th, the vehicle collision avoidance assistance device <NUM> determines that the second request condition Creq_2 is not satisfied.

The vehicle collision avoidance assistance device <NUM> acquires, as the driver's vehicle peripheral information I_S, information related to a road surface where the driver's vehicle <NUM> is traveling (road surface information Iroad) while the driver's vehicle <NUM> is traveling, and determines whether the forbiddance condition Cfbd is satisfied based on the road surface information Iroad.

Even when the forced braking is performed while the driver's vehicle <NUM> is traveling on a downhill with a large gradient, there is a possibility that the driver's vehicle <NUM> is not decelerated as expected. In such a case, it is preferable to avoid the collision between the driver's vehicle <NUM> and the object by forced steering instead of the forced braking.

When the forced steering is performed while the driver's vehicle <NUM> is traveling on a road surface having a large cant, the traveling behavior of the driver's vehicle <NUM> may become unstable.

To accurately acquire the road surface gradient GR and a road surface cant CT, the vehicle collision avoidance assistance device <NUM> first determines whether an absolute value of the acceleration of the driver's vehicle <NUM> (that is, the longitudinal acceleration Gx including a negative value) is equal to or smaller than a predetermined acceleration (upper limit acceleration Glimit) (that is, whether a road surface determination condition is satisfied).

When the vehicle collision avoidance assistance device <NUM> determines that the road surface determination condition is satisfied, the vehicle collision avoidance assistance device <NUM> acquires the road surface gradient GR and the road surface cant CT as the driver's vehicle peripheral information I_S. The road surface gradient GR and the road surface cant CT can be acquired by a predetermined method based on the peripheral detection information Idct.

The vehicle collision avoidance assistance device <NUM> determines whether the road surface gradient GR is smaller than zero and its absolute value is equal to or larger than a predetermined gradient (first gradient GR_1), and whether the absolute value of the road surface cant CT is equal to or larger than a predetermined value (predetermined cant CTth).

When the vehicle collision avoidance assistance device <NUM> determines that the road surface gradient GR is smaller than zero and its absolute value is equal to or larger than the first gradient GR_1, the vehicle collision avoidance assistance device <NUM> determines that the request condition Creq due to the road surface gradient (third request condition Creq_3) is satisfied. When the vehicle collision avoidance assistance device <NUM> determines that the road surface gradient GR is equal to or larger than zero or its absolute value is smaller than the first gradient GR_1 though the road surface gradient GR is smaller than zero, the vehicle collision avoidance assistance device <NUM> determines that the third request condition Creq_3 is not satisfied.

When the absolute value of the road surface cant CT is equal to or larger than the predetermined cant CTth, the vehicle collision avoidance assistance device <NUM> determines that the forbiddance condition Cfbd due to the road surface cant (first forbiddance condition Cfbd_1) is satisfied. When the absolute value of the road surface cant CT is smaller than the predetermined cant CTth, the vehicle collision avoidance assistance device <NUM> determines that the first forbiddance condition Cfbd_1 is not satisfied.

When the forced steering is performed while the driver's vehicle <NUM> is traveling on a road surface having a small coefficient of friction, the traveling behavior of the driver's vehicle <NUM> may become unstable. In such a case, it is preferable to avoid the collision between the driver's vehicle <NUM> and the object by forced braking instead of the forced steering.

Therefore, the vehicle collision avoidance assistance device <NUM> may acquire a road surface friction coefficient µ in addition to the road surface gradient GR as the driver's vehicle peripheral information I_S, and determine whether the third request condition Creq_3 is satisfied based on the road surface gradient GR and the road surface friction coefficient µ, instead of determining whether the third request condition Creq_3 is satisfied based only on the road surface gradient GR. The road surface friction coefficient µ can be acquired by a predetermined method based on the peripheral detection information Idct.

When the road surface friction coefficient µ is equal to or smaller than a predetermined friction coefficient µ_th and determination is made that the road surface gradient GR is smaller than zero and its absolute value is equal to or larger than the first gradient GR_1, the vehicle collision avoidance assistance device <NUM> determines that the request condition Creq due to the road surface gradient (third request condition Creq_3) is satisfied. When the road surface friction coefficient µ is equal to or smaller than a predetermined friction coefficient µ_th and determination is made that the road surface gradient GR is equal to or larger than zero or its absolute value is smaller than the first gradient GR_1 though the road surface gradient GR is smaller than zero, the vehicle collision avoidance assistance device <NUM> determines that the third request condition Creq_3 is not satisfied.

When the road surface friction coefficient µ is larger than the predetermined friction coefficient µ_th, the road surface gradient GR is smaller than zero, and its absolute value is equal to or larger than the first gradient GR_1 and equal to or smaller than a predetermined gradient (second gradient GR_2) that is larger than the first gradient GR_1, the vehicle collision avoidance assistance device <NUM> determines that the third request condition Creq_3 is satisfied. When the road surface friction coefficient µ is larger than the predetermined friction coefficient µ_th and the road surface gradient GR is equal to or larger than zero or its absolute value is smaller than the first gradient GR_1 or larger than the second gradient GR_2 though the road surface gradient GR is smaller than zero, the vehicle collision avoidance assistance device <NUM> determines that the third request condition Creq_3 is not satisfied.

When the traveling behavior of the driver's vehicle <NUM> is unstable while the driver's vehicle <NUM> is traveling, the vehicle collision avoidance assistance device <NUM> performs so-called vehicle stability control for stabilizing the traveling behavior of the driver's vehicle <NUM> by adjusting the driving force or the braking force to be applied to each wheel of the driver's vehicle <NUM> so that the traveling behavior of the driver's vehicle <NUM> stabilizes.

When the vehicle stability control is performed, the vehicle collision avoidance assistance device <NUM> determines that the forbiddance condition Cfbd due to the vehicle stability control (second forbiddance condition Cfbd_2) is satisfied. When the vehicle stability control is not performed, the vehicle collision avoidance assistance device <NUM> determines that the second forbiddance condition Cfbd_2 is not satisfied. In this way, the vehicle collision avoidance assistance device <NUM> acquires, as the driver's vehicle information I_100, information on whether the vehicle stability control is performed, and determines whether the forbiddance condition Cfbd is satisfied based on whether the vehicle stability control is performed.

While the driver's vehicle <NUM> is traveling, the vehicle collision avoidance assistance device <NUM> performs a process for detecting an object such as a vehicle ahead of the driver's vehicle <NUM> in the traveling direction based on the peripheral detection information Idct. The vehicle collision avoidance assistance device <NUM> executes normal traveling control while the vehicle collision avoidance assistance device <NUM> does not detect an object ahead of the driver's vehicle <NUM> in the traveling direction.

In the normal traveling control, when the requested drive torque TQ_D_req (requested driving force) is larger than zero, the operation of the drive device <NUM> is controlled to output the requested drive torque TQ_D_req from the drive device <NUM>. When the requested braking torque TQ_B_req (requested braking force) is larger than zero, the operation of the braking device <NUM> is controlled to output the requested braking torque TQ_B_req from the braking device <NUM>. When the requested steering torque TQs_req (requested steering force) is larger than zero, the operation of the steering device <NUM> is controlled to output the requested steering torque TQs_req from the steering device <NUM>.

When the vehicle collision avoidance assistance device <NUM> detects an object ahead of the driver's vehicle <NUM> in the traveling direction, the vehicle collision avoidance assistance device <NUM> determines whether the object is present in a predicted traveling area A100 based on the peripheral detection information Idct.

As illustrated in <FIG>, the predicted traveling area A100 is an area having a width equal to the width of the driver's vehicle <NUM> with its center corresponding to a predicted traveling route R100 of the driver's vehicle <NUM>. The predicted traveling route R100 is a traveling route where the driver's vehicle <NUM> is predicted to travel in the future when the driver's vehicle <NUM> travels while keeping the steering angle θ steer at that time. The predicted traveling route R100 illustrated in <FIG> is a straight line, but may be a curved line depending on situations.

When the detected object is not present in the predicted traveling area A100, the vehicle collision avoidance assistance device <NUM> continues the normal traveling control.

When an object <NUM> (in an example illustrated in <FIG>, a vehicle) is present in the predicted traveling area A100 as illustrated in <FIG>, the vehicle collision avoidance assistance device <NUM> recognizes the object <NUM> as the forward object 200F, and acquires "a distance between the forward object 200F and the driver's vehicle <NUM> (object distance D200)" and "a speed of the driver's vehicle <NUM> relative to the forward object 200F (relative speed ΔV200)" based on the peripheral detection information Idct.

The vehicle collision avoidance assistance device <NUM> acquires a predicted reach period TTC by calculation based on the acquired object distance D200 and the acquired relative speed ΔV200.

The predicted reach period TTC is a period that the driver's vehicle <NUM> is predicted to require to reach the forward object 200F. The vehicle collision avoidance assistance device <NUM> acquires the predicted reach period TTC by dividing the object distance D200 by the relative speed ΔV200 (TTC = D200 / ΔV200). The vehicle collision avoidance assistance device <NUM> acquires the object distance D200, the relative speed ΔV200, and the predicted reach period TTC in a predetermined calculation cycle while determining that the forward object 200F is present in the predicted traveling area A100.

The predicted reach period TTC decreases as the driver's vehicle <NUM> approaches the forward object 200F when the relative speed ΔV200 is constant.

The vehicle collision avoidance assistance device <NUM> continues the normal traveling control while the predicted reach period TTC is longer than a predetermined predicted reach period TTCth.

When the driver's vehicle <NUM> then approaches the forward object 200F and the predicted reach period TTC decreases to a predetermined period (predetermined predicted reach period TTCth) as illustrated in <FIG>, the vehicle collision avoidance assistance device <NUM> determines that a collision avoidance execution condition Cstart is satisfied.

That is, the vehicle collision avoidance assistance device <NUM> acquires the predicted reach period TTC as an index value indicating a possibility that the driver's vehicle <NUM> collides with the forward object 200F, and determines that the collision avoidance execution condition Cstart is satisfied when the index value is equal to or larger than a predetermined index value. In this case, the index value indicating the possibility that the driver's vehicle <NUM> collides with the forward object 200F increases as the predicted reach period TTC decreases.

When the vehicle collision avoidance assistance device <NUM> determines that the collision avoidance execution condition Cstart is satisfied, the vehicle collision avoidance assistance device <NUM> sets a target avoidance path Rtgt as illustrated in <FIG>. The target avoidance path Rtgt is a traveling path of the driver's vehicle <NUM> where the driver's vehicle <NUM> can pass by the side of the forward object 200F while traveling in the driver's vehicle lane LN.

In the example illustrated in <FIG>, the target avoidance path Rtgt is a path extending by a right side of the forward object 200F. When a space where the driver's vehicle <NUM> can pass by the side of the forward object 200F while traveling in the driver's vehicle lane LN is present on a left side of the forward object 200F, a path extending by the left side of the forward object 200F may be acquired as the target avoidance path Rtgt.

When the vehicle collision avoidance assistance device <NUM> cannot set the target avoidance path Rtgt because the space where the driver's vehicle <NUM> will pass is not present on the side of the forward object 200F, the vehicle collision avoidance assistance device <NUM> determines that the forbiddance condition Cfbd due to the collision avoidance path (third forbiddance condition Cfbd_3) is satisfied. When the target avoidance path Rtgt can be set, the vehicle collision avoidance assistance device <NUM> determines that the third forbiddance condition Cfbd_3 is not satisfied. In this way, the vehicle collision avoidance assistance device <NUM> acquires, as the driver's vehicle information I_100, the result of the determination as to whether the target avoidance path Rtgt can be set, and determines whether the third forbiddance condition Cfbd_3 is satisfied based on the determination result. Target Deceleration Setting.

When the vehicle collision avoidance assistance device <NUM> determines that the collision avoidance execution condition Cstart is satisfied, the vehicle collision avoidance assistance device <NUM> acquires, by calculation, a deceleration of the driver's vehicle <NUM> (target deceleration GDtgt) required to stop the driver's vehicle <NUM> by forced braking before colliding with the forward object 200F.

When the vehicle collision avoidance assistance device <NUM> determines that the collision avoidance execution condition Cstart is satisfied, the vehicle collision avoidance assistance device <NUM> determines whether the succeeding moving object <NUM> is present based on the peripheral detection information Idct.

As illustrated in <FIG>, the vehicle collision avoidance assistance device <NUM> determines that the succeeding moving object <NUM> is not present when no object is present behind the driver's vehicle <NUM>. When the succeeding moving object <NUM> is not present, the succeeding moving object <NUM> does not collide with the driver's vehicle <NUM> even if the forced braking is performed, and there is no need to avoid the collision between the driver's vehicle <NUM> and the forward object 200F by forced steering. Therefore, the vehicle collision avoidance assistance device <NUM> determines that the request condition Creq due to the succeeding moving object (fourth request condition Creq_4) is not satisfied.

When an object (in an example illustrated in <FIG>, a vehicle) is present behind the driver's vehicle <NUM> as illustrated in <FIG>, the vehicle collision avoidance assistance device <NUM> determines that the succeeding moving object <NUM> is present, and acquires a predicted moving area A300 of the succeeding moving object <NUM> based on the peripheral detection information Idct.

As illustrated in <FIG>, the predicted moving area A300 is an area having a width equal to the width of the succeeding moving object <NUM> with its center corresponding to a predicted moving route R300 of the succeeding moving object <NUM>. The predicted moving route R300 is a traveling route where the succeeding moving object <NUM> is predicted to travel in the future. The predicted moving route R300 illustrated in <FIG> is a straight line, but may be a curved line depending on situations.

The vehicle collision avoidance assistance device <NUM> determines whether the predicted moving area A300 and the predicted traveling area A100 overlap each other.

When the predicted moving area A300 and the predicted traveling area A100 have a relationship illustrated in <FIG>, the vehicle collision avoidance assistance device <NUM> determines that the predicted moving area A300 and the predicted traveling area A100 do not overlap each other. When the predicted moving area A300 and the predicted traveling area A100 do not overlap each other, the succeeding moving object <NUM> does not collide with the driver's vehicle <NUM> even if the forced braking is performed, and there is no need to avoid the collision between the driver's vehicle <NUM> and the forward object 200F by forced steering. Therefore, the vehicle collision avoidance assistance device <NUM> determines that the fourth request condition Creq_4 is not satisfied.

When the predicted moving area A300 and the predicted traveling area A100 have a relationship illustrated in <FIG>, the vehicle collision avoidance assistance device <NUM> determines that the predicted moving area A300 and the predicted traveling area A100 overlap each other, and determines, based on the peripheral detection information Idct, whether the succeeding moving object <NUM> may collide with the driver's vehicle <NUM> under the assumption that the forced braking is performed.

More specifically, the vehicle collision avoidance assistance device <NUM> acquires, by calculation, a distance by which the succeeding moving object <NUM> moves before the succeeding moving object <NUM> is stopped (required stop distance Dreq_stop) under the assumption that the succeeding moving object <NUM> starts decelerating at a maximum deceleration GDmax in response to the start of deceleration of the driver's vehicle <NUM> when a predetermined period Tth has elapsed since the driver's vehicle <NUM> started decelerating at the target deceleration GDtgt by starting forced braking. The predetermined period Tth is a period that may generally be required for the succeeding moving object <NUM> to start decelerating in response to the start of deceleration of the driver's vehicle <NUM>. The maximum deceleration GDmax is the maximum value of the deceleration that can be achieved by the succeeding moving object <NUM>.

The vehicle collision avoidance assistance device <NUM> acquires, by calculation, a period required for the succeeding moving object <NUM> to move by the required stop distance Dreq_stop (required stop period Treq_stop), and acquires, by calculation, a distance to be traveled by the driver's vehicle <NUM> within the required stop period Treq_stop during the forced braking (driver's vehicle traveling distance Dtravel).

When the required stop distance Dreq_stop is longer than the driver's vehicle traveling distance Dtravel, the vehicle collision avoidance assistance device <NUM> may determine that the succeeding moving object <NUM> may collide with the driver's vehicle <NUM> in the case where the forced braking is performed. In this example, the vehicle collision avoidance assistance device <NUM> determines that the succeeding moving object <NUM> may collide with the driver's vehicle <NUM> in the case where the forced braking is performed not only when the required stop distance Dreq_stop is longer than the driver's vehicle traveling distance Dtravel, but also when the required stop distance Dreq_stop is equal to or shorter than the driver's vehicle traveling distance Dtravel and a difference ΔD between the two distances is equal to or smaller than a predetermined distance ΔDth.

When the vehicle collision avoidance assistance device <NUM> determines that the succeeding moving object <NUM> may collide with the driver's vehicle <NUM> in the case where the forced braking is performed, it is preferable to avoid the collision between the driver's vehicle <NUM> and the forward object 200F by forced steering. Therefore, the vehicle collision avoidance assistance device <NUM> determines that the fourth request condition Creq_4 is satisfied. When the vehicle collision avoidance assistance device <NUM> determines that the succeeding moving object <NUM> will not collide with the driver's vehicle <NUM> even in the case where the forced braking is performed, the vehicle collision avoidance assistance device <NUM> determines that the fourth request condition Creq_4 is not satisfied.

According to the determination as to whether the fourth request condition Creq_4 is satisfied, the vehicle collision avoidance assistance device <NUM> determines that the fourth request condition Creq_4 is satisfied when determination is made that the predicted moving area A300 and the predicted traveling area A100 overlap each other and the succeeding moving object <NUM> is present within a range of a predetermined distance Dth from the driver's vehicle <NUM> based on the position of the succeeding moving object <NUM> (relative position P300 of the succeeding moving object <NUM> to the driver's vehicle <NUM>).

According to the determination as to whether the fourth request condition Creq_4 is satisfied, the vehicle collision avoidance assistance device <NUM> determines that the fourth request condition Creq_4 is not satisfied when determination is made that the predicted moving area A300 and the predicted traveling area A100 overlap each other and the succeeding moving object <NUM> is not present within the range of the predetermined distance Dth from the driver's vehicle <NUM> based on the position of the succeeding moving object <NUM>.

According to the determination as to whether the fourth request condition Creq_4 is satisfied, the vehicle collision avoidance assistance device <NUM> determines that the fourth request condition Creq_4 is not satisfied when determination is made that the predicted moving area A300 and the predicted traveling area A100 do not overlap each other, regardless of whether the succeeding moving object <NUM> is present within the range of the predetermined distance Dth from the driver's vehicle <NUM>.

As described above, the vehicle collision avoidance assistance device <NUM> in this example determines whether the fourth request condition Creq_4 is satisfied based on whether there is a collision possibility that the succeeding moving object <NUM> collides with the driver's vehicle <NUM> under the assumption that the forced braking is performed.

When none of the first request condition Creq_1 to the fourth request condition Creq_4 is satisfied, the vehicle collision avoidance assistance device <NUM> performs the forced braking regardless of whether the first forbiddance condition Cfbd_1 to the third forbiddance condition Cfbd_3 are satisfied.

When any one of the first forbiddance condition Cfbd_1 to the third forbiddance condition Cfbd_3 is satisfied, the vehicle collision avoidance assistance device <NUM> performs the forced braking even if any one of the first request condition Creq_1 to the fourth request condition Creq_4 is satisfied.

When the forced braking is started, the vehicle collision avoidance assistance device <NUM> controls the braking force to be applied to the driver's vehicle <NUM> to decelerate the driver's vehicle <NUM> at the target deceleration GDtgt. The vehicle collision avoidance assistance device <NUM> terminates the forced braking when the driver's vehicle <NUM> is stopped.

When any one of the first request condition Creq_1 to the fourth request condition Creq_4 is satisfied while none of the first forbiddance condition Cfbd_1 to the third forbiddance condition Cfbd_3 is satisfied, the vehicle collision avoidance assistance device <NUM> performs the forced steering.

When the forced steering is started, the vehicle collision avoidance assistance device <NUM> starts a process of controlling the steering torque TQs (steering force) to be output from the steering device <NUM> to cause the driver's vehicle <NUM> to travel along the target avoidance path Rtgt.

The vehicle collision avoidance assistance device <NUM> acquires a current position of the driver's vehicle <NUM> based on the longitudinal acceleration Gx, the lateral acceleration Gy, the yaw rate YR, the right and left lane marking lines LM, and the like during the forced steering, and controls the steering torque TQs to be output from the steering device <NUM> to cause the driver's vehicle <NUM> to travel along the target avoidance path Rtgt based on the acquired current position of the driver's vehicle <NUM>.

As a result, the driver's vehicle <NUM> starts to turn as illustrated in <FIG>, and passes by the side of the forward object 200F as illustrated in <FIG>. Thus, the collision between the driver's vehicle <NUM> and the forward object 200F is avoided.

The vehicle collision avoidance assistance device <NUM> terminates the forced steering when the driver's vehicle <NUM> has passed by the side of the forward object 200F as illustrated in <FIG>.

In addition to the forced steering, the vehicle collision avoidance assistance device <NUM> may decelerate the driver's vehicle <NUM> by reducing the driving force applied to the driver's vehicle <NUM>, limiting the driving force to a certain value or smaller, or applying a braking force to the driver's vehicle <NUM>. In this case, the vehicle collision avoidance assistance device <NUM> terminates the forced steering when the driver's vehicle <NUM> is stopped.

For example, when there is a possibility during the forced steering that the driver's vehicle <NUM> collides with another object such as a person who has appeared from behind the forward object 200F, the vehicle collision avoidance assistance device <NUM> may perform the forced braking by applying a braking force to the driver's vehicle <NUM> and forcibly stopping the driver's vehicle <NUM> to avoid a collision between the driver's vehicle <NUM> and the other object.

When the driver input torque TQs_driver is equal to or larger than a predetermined relatively large torque TQth during the forced steering, the vehicle collision avoidance assistance device <NUM> may stop the forced steering.

The above is the outline of the operation of the vehicle collision avoidance assistance device <NUM>. According to the above description, in a scene in which execution of the forced steering is preferable such that the request condition Creq is satisfied, the forced steering is performed except for a situation in which non-execution of the forced steering is preferable such that the forbiddance condition Cfbd is satisfied. Thus, an appropriate collision avoidance process is performed depending on the situation around the driver's vehicle <NUM>.

Next, specific operations of the vehicle collision avoidance assistance device <NUM> will be described. The CPU of the ECU <NUM> of the vehicle collision avoidance assistance device <NUM> executes a routine illustrated in <FIG> in a predetermined calculation cycle. At a predetermined timing, the CPU starts a process from Step <NUM> in <FIG>, and advances the process to Step <NUM> to determine whether the vehicle speed V100 of the driver's vehicle <NUM> is equal to or higher than the lower limit vehicle speed Vlimit and whether the road surface gradient GR is equal to or smaller than the upper limit gradient GRlimit.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to determine whether the brake pedal operation amount BP is equal to or larger than the predetermined brake pedal operation amount BPth.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to determine whether the deceleration GD of the driver's vehicle <NUM> is equal to or lower than the reference deceleration GDbase.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to increment the braking performance counter Cbrake. Next, the CPU advances the process to Step <NUM>.

When the CPU determines "No" in Step <NUM>, the CPU advances the process to Step <NUM> to decrement the braking performance counter Cbrake. Next, the CPU advances the process to Step <NUM>.

When the CPU advances the process to Step <NUM>, the CPU determines whether the braking performance counter Cbrake is equal to or larger than the predetermined value Cbrake_th.

When the CPU determines "Yes" in Step <NUM>, the CPU sets the value of a first request condition flag Xreq_1 to "<NUM>". The first request condition flag Xreq_1 indicates whether the first request condition Creq_1 is satisfied. When the value is "<NUM>", the first request condition flag Xreq_1 indicates that the first request condition Creq_1 is satisfied. When the value is "<NUM>", the first request condition flag Xreq_1 indicates that the first request condition Creq_1 is not satisfied.

Next, the CPU advances the process to Step <NUM> to temporarily terminate this routine.

When the CPU determines "No" in Step <NUM>, the CPU advances the process to Step <NUM> to set the value of the first request condition flag Xreq_1 to "<NUM>". Next, the CPU advances the process to Step <NUM> to temporarily terminate this routine.

When the CPU determines "No" in Step <NUM> or Step <NUM>, the CPU directly advances the process to Step <NUM> to temporarily terminate this routine.

The CPU executes a routine illustrated in <FIG> in a predetermined calculation cycle. At a predetermined timing, the CPU starts a process from Step <NUM> in <FIG>, and advances the process to Step <NUM> to determine whether the master cylinder pressure Pm is equal to or lower than the predetermined pressure Pm_th.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to set the value of a second request condition flag Xreq_2 to "<NUM>". The second request condition flag Xreq_2 indicates whether the second request condition Creq_2 is satisfied. When the value is "<NUM>", the second request condition flag Xreq_2 indicates that the second request condition Creq_2 is satisfied. When the value is "<NUM>", the second request condition flag Xreq_2 indicates that the second request condition Creq_2 is not satisfied.

When the CPU determines "No" in Step <NUM>, the CPU advances the process to Step <NUM> to set the value of the second request condition flag Xreq_2 to "<NUM>". Next, the CPU advances the process to Step <NUM> to temporarily terminate this routine.

The CPU executes a routine illustrated in <FIG> in a predetermined calculation cycle. At a predetermined timing, the CPU starts a process from Step <NUM> in <FIG>, and advances the process to Step <NUM> to determine whether the absolute value of the acceleration of the driver's vehicle <NUM> (longitudinal acceleration Gx) is equal to or smaller than the upper limit acceleration Glimit.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to acquire the road surface gradient GR. Next, the CPU advances the process to Step <NUM> to acquire the road surface cant CT. Next, the CPU advances the process to Step <NUM> to determine whether the road surface gradient GR is smaller than zero and its absolute value is equal to or larger than the first gradient GR_1.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to set the value of a third request condition flag Xreq_3 to "<NUM>". The third request condition flag Xreq_3 indicates whether the third request condition Creq_3 is satisfied. When the value is "<NUM>", the third request condition flag Xreq_3 indicates that the third request condition Creq_3 is satisfied. When the value is "<NUM>", the third request condition flag Xreq_3 indicates that the third request condition Creq_3 is not satisfied.

Next, the CPU advances the process to Step <NUM>.

When the CPU determines "No" in Step <NUM>, the CPU advances the process to Step <NUM> to set the value of the third request condition flag Xreq_3 to "<NUM>". Next, the CPU advances the process to Step <NUM>.

When the CPU advances the process to Step <NUM>, the CPU determines whether the road surface cant CT is equal to or larger than the predetermined cant CTth.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to set the value of a first forbiddance condition flag Xfbd_1 to "<NUM>". The first forbiddance condition flag Xfbd_1 indicates whether the first forbiddance condition Cfbd_1 is satisfied. When the value is "<NUM>", the first forbiddance condition flag Xfbd_1 indicates that the first forbiddance condition Cfbd_1 is satisfied. When the value is "<NUM>", the first forbiddance condition flag Xfbd_1 indicates that the first forbiddance condition Cfbd_1 is not satisfied.

When the CPU determines "No" in Step <NUM>, the CPU advances the process to Step <NUM> to set the value of the first forbiddance condition flag Xfbd_1 to "<NUM>". Next, the CPU advances the process to Step <NUM> to temporarily terminate this routine.

When the CPU determines "No" in Step <NUM>, the CPU directly advances the process to Step <NUM> to temporarily terminate this routine.

The CPU may execute a routine illustrated in <FIG> in a predetermined calculation cycle in place of the routine illustrated in <FIG>. At a predetermined timing, the CPU starts a process from Step <NUM> in <FIG>, and advances the process to Step <NUM> to determine whether the absolute value of the acceleration Gx of the driver's vehicle <NUM> is equal to or smaller than the upper limit acceleration Glimit.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to acquire the road surface gradient GR. Next, the CPU advances the process to Step <NUM> to acquire the road surface cant CT. Next, the CPU advances the process to Step <NUM> to acquire the road surface friction coefficient µ. Next, the CPU advances the process to Step <NUM> to determine whether the road surface friction coefficient µ is equal to or larger than the predetermined friction coefficient µ_th.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to determine whether the road surface gradient GR is smaller than zero and its absolute value is equal to or larger than the first gradient GR_1.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to set the value of the third request condition flag Xreq_3 to "<NUM>". Next, the CPU advances the process to Step <NUM>.

When the CPU determines "No" in Step <NUM>, the CPU advances the process to Step <NUM> to execute a routine illustrated in <FIG>. When the CPU advances the process to Step <NUM>, the CPU starts a process from Step <NUM> in <FIG>, and advances the process to Step <NUM> to determine whether the road surface gradient GR is smaller than zero and its absolute value is equal to or larger than the first gradient GR_1 and equal to or smaller than the second gradient GR_2.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to set the value of the third request condition flag Xreq_3 to "<NUM>". Next, the CPU advances the process to Step <NUM> in <FIG> via Step <NUM>.

When the CPU determines "No" in Step <NUM>, the CPU advances the process to Step <NUM> to set the value of the third request condition flag Xreq_3 to "<NUM>". Next, the CPU advances the process to Step <NUM> in <FIG> via Step <NUM>.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to set the value of the first forbiddance condition flag Xfbd_1 to "<NUM>". Next, the CPU advances the process to Step <NUM> to temporarily terminate this routine.

The CPU executes a routine illustrated in <FIG> in a predetermined calculation cycle. At a predetermined timing, the CPU starts a process from Step <NUM> in <FIG>, and advances the process to Step <NUM> to determine whether the condition for performing the vehicle stability control is satisfied.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to start the vehicle stability control. Next, the CPU advances the process to Step <NUM> to set the value of a second forbiddance condition flag Xfbd_2 to "<NUM>". The second forbiddance condition flag Xfbd_2 indicates whether the second forbiddance condition Cfbd_2 is satisfied. When the value is "<NUM>", the second forbiddance condition flag Xfbd_2 indicates that the second forbiddance condition Cfbd_2 is satisfied. When the value is "<NUM>", the second forbiddance condition flag Xfbd_2 indicates that the second forbiddance condition Cfbd_2 is not satisfied.

When the CPU determines "No" in Step <NUM>, the CPU advances the process to Step <NUM> to determine whether the condition for terminating the vehicle stability control is satisfied.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to terminate the vehicle stability control. Next, the CPU advances the process to Step <NUM> to set the value of the second forbiddance condition flag Xfbd_2 to "<NUM>". Next, the CPU advances the process to Step <NUM> to temporarily terminate this routine.

The CPU executes a routine illustrated in <FIG> in a predetermined calculation cycle. At a predetermined timing, the CPU starts a process from Step <NUM> in <FIG>, and advances the process to Step <NUM> to determine whether the forward object 200F is detected.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to acquire the predicted reach period TTC. Next, the CPU advances the process to Step <NUM> to determine whether the predicted reach period TTC is equal to or shorter than the predetermined predicted reach period TTCth.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to execute a routine illustrated in <FIG>. When the CPU advances the process to Step <NUM>, the CPU starts a process from Step <NUM> in <FIG>, and advances the process to Step <NUM> to set the target avoidance path Rtgt. Next, the CPU advances the process to Step <NUM> to determine whether the target avoidance path Rtgt can be set.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to set the value of a third forbiddance condition flag Xfbd_3 to "<NUM>". The third forbiddance condition flag Xfbd_3 indicates whether the third forbiddance condition Cfbd_3 is satisfied. When the value is "<NUM>", the third forbiddance condition flag Xfbd_3 indicates that the third forbiddance condition Cfbd_3 is satisfied. When the value is "<NUM>", the third forbiddance condition flag Xfbd_3 indicates that the third forbiddance condition Cfbd_3 is not satisfied.

Next, the CPU advances the process to Step <NUM> in <FIG> via Step <NUM>.

When the CPU determines "No" in Step <NUM>, the CPU advances the process to Step <NUM> to set the value of the third forbiddance condition flag Xfbd_3 to "<NUM>". Next, the CPU advances the process to Step <NUM> in <FIG> via Step <NUM>.

When the CPU advances the process to Step <NUM> in <FIG>, the CPU acquires the target deceleration GDtgt. Next, the CPU advances the process to Step <NUM> to determine whether the succeeding moving object <NUM> is detected.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to execute a routine illustrated in <FIG>. When the CPU advances the process to Step <NUM>, the CPU starts a process from Step <NUM> in <FIG>, and advances the process to Step <NUM> to acquire the predicted traveling area A100. Next, the CPU advances the process to Step <NUM> to acquire the predicted moving area A300. Next, the CPU advances the process to Step <NUM> to determine whether the predicted moving area A300 and the predicted traveling area A100 overlap each other.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to acquire the required stop distance Dreq_stop and the driver's vehicle traveling distance Dtravel. Next, the CPU advances the process to Step <NUM> to determine whether the required stop distance Dreq_stop is equal to or longer than a distance obtained by subtracting the predetermined distance ΔDth from the driver's vehicle traveling distance Dtravel.

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to set the value of a fourth request condition flag Xreq_4 to "<NUM>". The fourth request condition flag Xreq_4 indicates whether the fourth request condition Creq_4 is satisfied. When the value is "<NUM>", the fourth request condition flag Xreq_4 indicates that the fourth request condition Creq_4 is satisfied. When the value is "<NUM>", the fourth request condition flag Xreq_4 indicates that the fourth request condition Creq_4 is not satisfied.

When the CPU determines "No" in Step <NUM>, the CPU advances the process to Step <NUM> to set the value of the fourth request condition flag Xreq_4 to "<NUM>". Next, the CPU advances the process to Step <NUM> in <FIG> via Step <NUM>.

When the CPU advances the process to Step <NUM> in <FIG>, the CPU determines whether all the values of the first request condition flag Xreq_1 to the fourth request condition flag Xreq_4 are "<NUM>".

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to perform the forced braking. Next, the CPU advances the process to Step <NUM> to temporarily terminate this routine.

When the CPU determines "No" in Step <NUM>, the CPU advances the process to Step <NUM> to determine whether all the values of the first forbiddance condition flag Xfbd_1 to the third forbiddance condition flag Xfbd_3 are "<NUM>".

When the CPU determines "Yes" in Step <NUM>, the CPU advances the process to Step <NUM> to perform the forced steering. Next, the CPU advances the process to Step <NUM> to temporarily terminate this routine.

When the CPU determines "No" in Step <NUM>, the CPU advances the process to Step <NUM> to perform the forced braking. Next, the CPU advances the process to Step <NUM> to temporarily terminate this routine.

The above are the specific operations of the vehicle collision avoidance assistance device <NUM>.

Claim 1:
A vehicle collision avoidance assistance device (<NUM>) comprising a processor configured to:
perform forced braking or forced steering when a driver's vehicle (<NUM>) has a possibility of colliding with an object (<NUM>) ahead of the driver's vehicle (<NUM>), the forced braking being braking for avoiding a collision between the driver's vehicle (<NUM>) and the object (<NUM>) by applying a braking force to the driver's vehicle (<NUM>) to stop the driver's vehicle (<NUM>) before the driver's vehicle (<NUM>) collides with the object (<NUM>), the forced steering being steering for avoiding the collision between the driver's vehicle (<NUM>) and the object (<NUM>) by steering the driver's vehicle (<NUM>) to pass by a side of the object (<NUM>);
acquire at least one of information related to a condition of the driver's vehicle (<NUM>) and information related to a situation around the driver's vehicle (<NUM>);
determine, based on the acquired information, whether a request condition for requesting execution of the forced steering is satisfied and whether a forbiddance condition for forbidding the execution of the forced steering is satisfied;
perform, when the request condition is not satisfied, the forced braking regardless of whether the forbiddance condition is satisfied;
perform the forced steering when the forbiddance condition is not satisfied and the request condition is satisfied; and
perform, when the forbiddance condition is satisfied, the forced braking though the request condition is satisfied, characterized in that the processor is configured to:
determine that the request condition is satisfied when the processor determines that the braking device (<NUM>) deteriorates based on a deterioration status of the braking device (<NUM>), or when the processor determines that a weight of the driver's vehicle is equal to or larger than a predetermined weight; and
determine that the request condition is not satisfied when the processor determines that the braking device (<NUM>) does not deteriorate based on the deterioration status of the braking device (<NUM>), or when the processor determines that the weight of the driver's vehicle is smaller than the predetermined weight.