If a subsequent object threat is detected at a location within a boundary region, the vehicle control module may inhibit automatic braking and avoid a subsequent RVB event alert. For example, the system may prevent repeated automatic braking and RVB event alerts for detection of object threats at a same location (or a location within a same boundary region) for which a previous automatic braking and RVB event alert was issued. This may prevent multiple automatic breaking events for a same object that a driver is already aware of.

For example, as shown in FIG. 3, at time t2.2 a third object threat 120 is detected. The third object threat 120 is located within the boundary region 116C corresponding to the first object 106. Because the vehicle control module already issued an RVB event alert for the first object 106 at a previous time, the vehicle control module may avoid issuing another RVB event for the newly detected third object threat 120 (e.g., because the newly detected third object threat 120 may be the same as the first object 106 that the driver is already aware of from the previous RVB event alert).

At the time t2.2, the vehicle control module may also detect a fourth object threat 122 and a fifth object threat 124 which are outside of the boundary regions. If the vehicle crosses a TTC threshold with respect to the fourth object threat 122 or the fifth object threat 124, the vehicle control module may automatically apply the brakes and generate another RVB event alert (e.g., because the fourth object threat 122 and the fifth object threat 124 are at locations where threat objects have not previously been alerted for the driver).

The boundary regions may decay over time, such that new object threats detected within a prior boundary region may be allowed to initiate automatic vehicle braking and RVB event alerts again. For example, at time t2.3, the boundary region 118C corresponding to the second object 108 may be dropped, due to a specified period of time elapsing after initial detection of the second object 108 or an initial RVB event based on the second object 108.

For example, if a first object detection or RVB event based on the second object 108 occurs at time to, the location may only be tracked for a specified period of time, before new alerts can be generated at the same location. If a driver is alerted to an RVB event based on the location of the second object 108, subsequent object threat detections at the same location may be inhibited for five seconds, ten seconds, thirty seconds, etc. (e.g., because the vehicle control module assumes the driver is aware of the detected and alerted object threat for that period of time). After the period of time ends, new object threats detected at that location may initiate automatic braking and RVB event alerts (in case the driver forgot about the object, if a new object may be present at a similar location, etc.).

In some example embodiments, a subsequent detection of an object threat within a boundary region may pause or reset a decay of the boundary region. For example, if another object threat is detected within a boundary region at a time after the initial RVB event, the amount of time before the boundary region is dropped may be extended.

In the example of FIG. 3, at time t2.3 the boundary region 118C corresponding to the second object 108 is dropped after a specified time period expires (e.g., five seconds, ten seconds, thirty seconds, etc.), and no additional object threats are detected within the boundary region 118C. In contrast, the boundary region 116 corresponding to the first object 106 is still present at the time t2.3, due to the detection of the third object threat 120 within the boundary region 116C at time t2.2 (which extended the duration of the boundary region 116C).

FIG. 4 is a diagram illustrating a second reverse travel path trajectory of the vehicle of FIG. 2A. As shown in FIG. 4, the vehicle is at a third vehicle position 110C, moving along a second reverse travel path 105. For example, backing up to generate an initial RVB event, and then pulling forwards along the forward travel path 103, the vehicle may again back up towards the location of the first object 106 along a second reverse travel path 105 at time t3.

As shown in FIG. 4, the boundary region 116C corresponding to the first object 106 is still present, while the boundary region corresponding to the location of the second object 108 has decayed away. Therefore, if the vehicle control module detects another object threat within the boundary region 116C a subsequent RVB event and automatic braking may be inhibited. However, if the vehicle control module detects the fourth object threat 122 or the fifth object threat 124 adjacent to the old location of the second object 108, another RVB event alert or automatic braking may occur for the fourth object threat 122 or the fifth object threat 124. In some example embodiments, detection of objects may be implemented any combination of vehicle movements, such as 1. Rear movement→brake→rear movement; 2. Rear movement→forward movement→rear movement; 3. Forward movement→brake→forward movement, etc.

FIG. 5 is a flowchart depicting an example process for controlling automatic vehicle braking in response to rear virtual bumper events. The process may be performed by, for example, the vehicle control module 20 of FIG. 1. At 504, a rear virtual bumper (RVB) event occurs (e.g., due to a detected object threat in a rear travel path of the vehicle).

At 508, the vehicle control module is configured to determine a location of the object threat for which the RVB event occurred. For example, the vehicle control module may use signals received from one or more vehicle object detectors in order to determine a location of the detected object threat.

At 512, control is configured to define a boundary region around a location of the object threat. The boundary region may have any suitable size, such as a circle with a diameter of about ten centimeters, about twenty centimeters, about fifty centimeters, about one meter, etc.

The vehicle control module is configured to track a location of a target relative to vehicle movement using dead reckoning, at 516. Further details of an example dead reckoning algorithm for tracking target location relative to movement of a vehicle is described further below with reference to FIG. 6.

At 520, control receives a new object threat detection (such as via one or more object sensors of the vehicle). Control then compares a location of the new object threat to the boundary region at 524.

If the location of the new object threat is within the boundary region at 528, control proceeds to 532 to inhibit automatic braking and alert, to avoid a subsequent RVB event. Control then returns to 516 to continue monitoring a location of the target relative to movement of the vehicle.

If the location of the new object threat is not within the boundary region at 528, control proceeds to 536 to automatically apply the vehicle brakes and generate a new RVB alert. Control then determines a location of the newly detected object threat at 540, and returns to 512 to define a new boundary region for the newly detected object threat.

FIG. 6 is a flowchart depicting an example process for dead reckoning a position of an object threat relative to motion of a vehicle. The process may be performed by, for example, the vehicle control module 20 of FIG. 1. At 604, the vehicle control module is configured to obtain a position of the detected object threat.

At 608, the vehicle control module is configured to estimate a changed position of the vehicle using dead reckoning. An example equation for executing a dead reckoning algorithm to estimate a position of a host vehicle is provided below:

Host
⁢

Vehicle
⁢

heading
⁢

angle
⁢

h
:
h

+

W
z

*
dt

⁢

Host
⁢

Vehicle
⁢

x
⁢

position
⁢

h
x

:

h
x

+

cos
⁡
(
h
)

*
dx

+

sin
⁡
(
h
)

*
dy

⁢

Host
⁢

Vehicle
⁢

y
⁢

position
⁢

h
y

:

h
y

+

sin
⁡
(
h
)

*
dx

+

cos
⁡
(
h
)

*
dy

⁢

Where
⁢

dx

=

v
x

*
dt

;

dy
=

v
y

*
dt

⁢

[

h
x

h
y

]

=

[

cos
⁡
(
h
)

sin
⁡
(
h
)

h
x

sin
⁡
(
h
)

cos
⁡
(
h
)

h
y

]

[

v
x

·
dt

v
y

·
dt

1

]

Control then transforms the coordinates of the object threat position with respect to an estimated new position of the vehicle at 612 (e.g., due to the dead reckoning vehicle position update). An equation for transforming coordinates of a location of a detected object threat into a new coordinate system based on dead reckoning of the vehicle position is provided below:

[

P_Hi
-
ThObjx_T

P_Hi
-
ThObjy_T

]

=

[

cos
⁡
(
h
)

sin
⁡
(
h
)

-

sin
⁡
(
h
)

cos
⁡
(
h
)

]

[

P_Hi
-
ThObjx
-

h
x

P_Hi
-
ThObjy
-

h
y

]

At 616, the vehicle control module is configured to report updated coordinates of the object threat position with respect to the vehicle.

FIG. 7