U.S. patent application number 13/941894 was filed with the patent office on 2015-01-15 for post-impact path assist for vehicles.
The applicant listed for this patent is FORD GLOBAL TECHNOLOGIES, LLC. Invention is credited to Jianbo Lu, Stephen W. Rouhana.
Application Number | 20150019063 13/941894 |
Document ID | / |
Family ID | 52107567 |
Filed Date | 2015-01-15 |
United States Patent
Application |
20150019063 |
Kind Code |
A1 |
Lu; Jianbo ; et al. |
January 15, 2015 |
POST-IMPACT PATH ASSIST FOR VEHICLES
Abstract
An environment monitor has a plurality of sensors for detecting
predetermined safety risks associated with a plurality of potential
destination regions around a vehicle as the vehicle moves over a
roadway. The environment monitor selects one of the potential
destination regions having a substantially lowest safety risk as a
target area. A path determination unit assembles a plurality of
plausible paths between the vehicle and the target area, monitors
predetermined safety risks associated with the plurality of
plausible paths, and selects one of the plausible paths having a
substantially lowest safety risk as a target path. An impact
detector detects an impact between the vehicle and another object.
A stability control is configured to autonomously steer the vehicle
onto the target path when the impact is detected.
Inventors: |
Lu; Jianbo; (Northville,
MI) ; Rouhana; Stephen W.; (Plymouth, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FORD GLOBAL TECHNOLOGIES, LLC |
Dearborn |
MI |
US |
|
|
Family ID: |
52107567 |
Appl. No.: |
13/941894 |
Filed: |
July 15, 2013 |
Current U.S.
Class: |
701/25 |
Current CPC
Class: |
B60K 28/14 20130101;
G05D 2201/0213 20130101; B60W 40/04 20130101; G05D 1/0214 20130101;
B60W 2030/082 20130101 |
Class at
Publication: |
701/25 |
International
Class: |
G05D 1/00 20060101
G05D001/00 |
Claims
1. A vehicle comprising: an environment monitor having a plurality
of sensors for detecting predetermined safety risks associated with
a plurality of potential destination regions around the vehicle as
the vehicle moves over a roadway, wherein the environment monitor
selects one of the potential destination regions having a
substantially lowest safety risk as a target area; a path
determination unit assembling a plurality of plausible paths
between the vehicle and the target area, monitoring predetermined
safety risks associated with the plurality of plausible paths, and
selecting one of the plausible paths having a substantially lowest
safety risk as a target path; an impact detector for detecting an
impact between the vehicle and another object; and a stability
control configured to autonomously steer the vehicle onto the
target path when the impact is detected, wherein the environment
monitor and the path determination unit select the target area and
the target path, respectively, before the impact occurs.
2. The vehicle of claim 1 wherein the predetermined safety risks
include fixed obstructions and moving objects representing a
potential collision.
3. The vehicle of claim 1 wherein the predetermined safety risks
include unsafe surface properties and steep grades.
4. The vehicle of claim 1 wherein the stability control is
configured to stop the vehicle in the target area.
5. (canceled)
6. The vehicle of claim 1 wherein the target area and the target
path are updated substantially continuously while the vehicle is
moving.
7. The vehicle of claim 6 wherein the target area and the target
path continue to be updated after detecting the impact.
8. The vehicle of claim 1 wherein the potential destination regions
are comprised of a predetermined grid defined in relation to the
vehicle.
9. The vehicle of claim 1 wherein the plurality of sensors includes
at least one sensor selected from the group comprising a radar
sensor, a lidar sensor, an ultrasonic sensor, an optical sensor, a
night vision sensor, a remote communication system, and a
geopositioning system.
10. The vehicle of claim 1 wherein the path determination unit
assembles the plausible paths according to a current speed and a
maximum yaw for the vehicle.
11. A method of controlling a vehicle comprising the steps of:
monitoring a plurality of sensors for detecting predetermined
safety risks associated with a plurality of potential destination
regions around the vehicle as the vehicle moves over a roadway;
selecting one of the potential destination regions having a
substantially lowest safety risk as a target area; determining a
plurality of plausible paths between the vehicle and the target
area; monitoring predetermined safety risks associated with the
plurality of plausible paths; selecting one of the plausible paths
having a substantially lowest safety risk as a target path;
detecting an occurrence of an impact of the vehicle with another
object, wherein the selection of the target path as one of the
plausible paths having a substantially lowest safety risk is made
before detection of the impact; and activating an autonomous path
control to follow the target path to the target area in response to
detecting the impact.
12. The method of claim 11 wherein the predetermined safety risks
include fixed obstructions and moving objects representing a
potential collision.
13. The method of claim 11 wherein the predetermined safety risks
include unsafe surface properties and steep grades.
14. The method of claim 11 further comprising the step of stopping
the vehicle in the target area.
15. (canceled)
16. The method of claim 11 wherein the monitoring and selecting
steps are performed substantially continuously while the vehicle is
moving.
17. The method of claim 16 wherein the target area and the target
path continue to be updated after detecting the impact.
18. The method of claim 11 wherein the potential destination
regions are comprised of a predetermined grid defined in relation
to the vehicle.
19. The method of claim 11 wherein the plurality of sensors
includes at least one sensor selected from the group comprising a
radar sensor, a lidar sensor, an ultrasonic sensor, an optical
sensor, a night vision sensor, a remote communication system, and a
geopositioning system.
20. The method of claim 11 wherein the plurality of plausible paths
are determined according to a current speed and a maximum yaw for
the vehicle.
21. A vehicle comprising: an environment monitor having a plurality
of sensors for detecting predetermined safety risks associated with
a plurality of potential destination regions around the vehicle as
the vehicle moves over a roadway, wherein the environment monitor
selects one of the potential destination regions having a
substantially lowest safety risk as a target area, and wherein the
predetermined safety risks include unsafe surface properties and
steep grades; a path determination unit assembling a plurality of
plausible paths between the vehicle and the target area, monitoring
predetermined safety risks associated with the plurality of
plausible paths, and selecting one of the plausible paths having a
substantially lowest safety risk as a target path; an impact
detector for detecting an impact between the vehicle and another
object; and a stability control configured to autonomously steer
the vehicle onto the target path when the impact is detected.
22. A vehicle comprising: an environment monitor having a plurality
of sensors for detecting predetermined safety risks associated with
a plurality of potential destination regions around the vehicle as
the vehicle moves over a roadway, wherein the environment monitor
selects one of the potential destination regions having a
substantially lowest safety risk as a target area, and wherein the
potential destination regions are comprised of a predetermined grid
defined in relation to the vehicle; a path determination unit
assembling a plurality of plausible paths between the vehicle and
the target area, monitoring predetermined safety risks associated
with the plurality of plausible paths, and selecting one of the
plausible paths having a substantially lowest safety risk as a
target path; an impact detector for detecting an impact between the
vehicle and another object; and a stability control configured to
autonomously steer the vehicle onto the target path when the impact
is detected.
23. A vehicle comprising: an environment monitor having a plurality
of sensors for detecting predetermined safety risks associated with
a plurality of potential destination regions around the vehicle as
the vehicle moves over a roadway, wherein the environment monitor
selects one of the potential destination regions having a
substantially lowest safety risk as a target area; a path
determination unit assembling a plurality of plausible paths
between the vehicle and the target area, monitoring predetermined
safety risks associated with the plurality of plausible paths, and
selecting one of the plausible paths having a substantially lowest
safety risk as a target path, wherein the path determination unit
assembles the plausible paths according to a current speed and a
maximum yaw for the vehicle; an impact detector for detecting an
impact between the vehicle and another object; and a stability
control configured to autonomously steer the vehicle onto the
target path when the impact is detected.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] Not Applicable.
BACKGROUND OF THE INVENTION
[0003] The present invention relates in general to autonomous
vehicle control, and, more specifically, to planning and following
a post-impact path that reduces risks of secondary crash
events.
[0004] Several vehicle control systems currently exist which are
used to augment the driving capability of a vehicle operator such
as antilock brake systems (ABS), traction control systems (TCS),
and stability control systems (SC). Example of stability control
systems include electronic stability control (ESC) systems
(sometimes referred to as yaw stability control (YSC) systems) and
roll stability control (RSC) systems. ESC systems are also
sometimes called ESP (Electronic Stability Program) systems or DSTC
(Dynamic Stability Traction Control) systems.
[0005] The stability control systems are utilized to maintain
controlled and stable vehicle operations for improved vehicle and
occupant safety. The stability control systems are often used to
maintain control of a vehicle following a driver's desired travel
direction, to prevent the vehicle from spinning out, and/or to
prevent or mitigate a roll over event. For example, a yaw stability
control system typically compares the driver's desired heading
based upon the steering wheel angle with the path of travel as
determined from motion sensors located on the vehicle. By
regulating the amount of braking at each corner of the vehicle and
the traction force of the vehicle, the desired path of travel may
be maintained.
[0006] Existing stability control systems correct undesired vehicle
motion caused by a tire force disturbance (TFD), such as a tire
force differential due to a road surface disturbance or due to a
mismatch between the driving intention of a driver and a road
surface condition. This mismatch usually happens when there is a
significant difference between the front and the rear tire lateral
forces applied to the vehicle (referred to as the lateral tire
force differential), or there is a significant difference between
the right and the left tire longitudinal tire forces (referred to
as the longitudinal tire force differential), or a combination
thereof.
[0007] An undesired yaw motion may also be generated by a yaw
moment disturbance caused when a vehicle receives a force
disturbance other than a tire force disturbance. A body force
disturbance (BFD) may occur when a vehicle hits a fixed object,
such as a tree, or when the vehicle is hit by another moving
object, such as a vehicle. A body force disturbance may also occur
when the vehicle experiences a sudden strong wind gust applied to
the vehicle body. While the magnitude of the tire force disturbance
is limited by the driving condition of the road surface, the
magnitude of a body force disturbance can be essentially unlimited.
For example, the collision of two moving vehicles may generate a
body force disturbance with a magnitude that is several factors
larger than the total tire forces. A yaw motion may be generated
when a vehicle receives a body force disturbance from an external
source, resulting in an altered vehicle trajectory or path which
can result in a secondary impact event. In many situations, the
risk of injury or damage can be much greater from a secondary event
than from the primary event.
[0008] Stability control systems aid a vehicle driver in pursuing
an intended action or trajectory. As a result of the impending or
actual application of a body force disturbance, however, a driver
may panic and perform driving tasks that are inappropriate or
drastic in an attempt to avoid receiving the external body force
disturbance which can lead to further undesirable events. Some
studies have shown that about one third of all vehicle-to-vehicle
accidents that cause severe injuries involve more than one impact.
A relatively small first impact is very often followed by a severe
second impact. This second impact can include one of many types of
impacts, such as vehicle-to-vehicle collisions, vehicle-to-object
collisions, tripped or untripped roll-overs, and road
departures.
[0009] It would be desirable to automatically react to impact
events while taking into account to possibility of erroneous
driver's action in a manner that reduces the likelihood and/or
severity of secondary impact events.
SUMMARY OF THE INVENTION
[0010] In one aspect of the invention, a vehicle is comprised of an
environment monitor having a plurality of sensors for detecting
predetermined safety risks associated with a plurality of potential
destination regions around the vehicle as the vehicle moves over a
roadway. The environment monitor selects one of the potential
destination regions having a substantially lowest safety risk
(e.g., risk of a secondary collision) as a target area. A path
determination unit assembles a plurality of plausible paths between
the vehicle and the target area, monitors predetermined safety
risks associated with the plurality of plausible paths, and selects
one of the plausible paths having a substantially lowest safety
risk as a target path. An impact detector detects an impact between
the vehicle and another object. A stability control is configured
to autonomously steer the vehicle onto the target path when the
impact is detected.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 depicts an initial collision and a safe path to
follow after the impact.
[0012] FIG. 2 is a diagram showing a grid used to identify a safest
area and a safest path to reach it.
[0013] FIG. 3 is a block diagram showing one embodiment of
apparatus according to the present invention.
[0014] FIG. 4 is a flowchart showing one preferred method of the
invention.
[0015] FIG. 5 is a block diagram showing an alternative
embodiment.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0016] According to the present invention, when a vehicle has
received an impact which may have put it on course to hit another
object or to move along an unfavorable path (e.g., a heavy traffic
lane or an unsafe situation such as a lake or a steep slope), an
autonomous vehicle control system such as torque vectoring, active
steering, active braking, or active throttling is engaged in order
to initiate a path correction action to avoid the unfavorable
path.
[0017] An apparatus of the invention may prevent further occupant
injury after a primary crash. A sensing system is used to monitor
surroundings and identify an area A.sub.LR having a substantially
lowest risk of potential secondary crashes if the host vehicle
would move into that area. A plausible path determination unit
assembles all the plausible paths that could be followed to reach
the low risk area A.sub.LR. A path planning system working in or
with the path determination unit selects a path having a
substantially lowest safety risk out of all the plausible paths.
Identification of a low risk area A.sub.LR and selection of a path
are performed substantially continuously while the vehicle is in
motion so that they can be immediately used in the event of a
collision. An impact detection system detects the occurrence of an
impact. In response to the impact, a vehicle stabilization means is
activated in order to follow the selected path. Preferably, the
sensing and path planning systems continue to monitor changing
risks and the selected path is appropriately updated according to
the changing risks.
[0018] The sensing system may preferably evaluate predetermined
safety risks in order to identify the lowest risk area A.sub.LR and
the lowest risk path based on information from radar sensors, lidar
sensors, ultrasonic sensors, vision sensors (cameras), night
vision, or other sensors (many of which may be already present on a
vehicle in connection with a forward collision warning system, an
adaptive cruise control system, or a reverse parking aid) or from
remote information obtained from vehicle-to-infrastructure systems,
vehicle-to-vehicle communication systems, cloud communication
systems, or from navigation and digital map systems.
[0019] The lowest risk area A.sub.LR can be identified by excluding
areas in a surrounding grid that have a high probability of
secondary collision or other hazards, using all available
environmental sensors. Such hazards could include an area or path
leading to a lake, a steep hill, an off-road terrain with
embankment, a heavy traffic region with oncoming traffic flow, a
potential vehicle-to-vehicle impact, an area which might cause
tripped rollover, or a path towards fixed objects such as poles,
trees, and buildings.
[0020] The impact detector may include vehicle crash sensors,
vehicle motion sensors, or other post-impact stability control
sensors. The vehicle stabilization control used to follow the
desired path after impact may preferably be the same as what is
used on the vehicle to provide driver assistance prior to the
impact event. The invention constantly calculates the lowest risk
paths during driving and then uses a first impact as a trigger to
initiate autonomous driving functions through torque vectoring,
active steering, active braking, active throttling, or active
steering assist (EPAS), for example. An autonomous driving function
after the vehicle receives an impact can force a vehicle to move
along a safe path even if a driver's control commands are absent or
represent inappropriate control actions. In the event that the
driver is correctly steering the vehicle towards the safe path
direction, then the invention can facilitate the driver's control
in a timely fashion. If the vehicle's kinetic energy can be
attenuated enough to bring it to a stop inside the lowest risk
area, then the autonomous driving function can also be used to stop
the vehicle.
[0021] Referring now to FIG. 1, a host vehicle 10 is moving over a
roadway 11 toward an intersection. A second moving vehicle 12 is
shown entering the intersection to cause a collision, with the
impact occurring at a position 13. The trajectory of host vehicle
10 is altered by the collision. Vehicle 10 could be put on course
toward a secondary impact with a fixed pole 14, nearby vehicles 15
and 16, or a pond 17, for example. The driver may be unable to
steer to a safe area or may inadvertently initiate control actions
inconsistent with avoiding a secondary impact. Therefore, the
present invention automatically identifies a safe area 18 having a
lowest safety risk together with a path 19 with the best likelihood
of safely reaching area 18. Using remote sensing to identify
potential safety risks, the present invention utilizes a grid 20
divided into a plurality of potential destination regions laid out
over the area in the immediate vicinity of vehicle 10. Some of the
potential destination regions are numbered 21-25, 28, 31-34, 38,
and 40-44. Each potential destination region lies at a respective
heading angle and respective distance from vehicle 10, and may
preferably have a width and length with approximately the same size
and shape as a footprint of vehicle 10. Using remote object
detection, classification, and tracking, each detected occurrence
of a safety risk is mapped to the corresponding potential
destination regions. For example, any sites where a secondary
collision event is expected to occur (e.g., with a fixed obstacle
or a moving object, or having unsafe road surface properties or
steep grades) may be excluded from consideration as either a safe
target area or a safe path. Thus, a plurality of regions 40-43 are
shaded as an indication that they will be avoided in selecting the
target area or target path.
[0022] For any regions not excluded from consideration, other
safety risks may be quantified and other factors taken into
consideration in assigning a risk value. A particular risk value
may reflect the proximity of a region to other regions representing
known safety risks, for example. In FIG. 2, a region 44 has been
evaluated as having the lowest safety risk. Thus, it becomes a
target area of lowest risk A.sub.LR under the present
invention.
[0023] Once target area A.sub.LR has been selected, a plurality of
plausible paths 45-47 are assembled (i.e., defined) based on
various properties of the vehicle control system, a sensed vehicle
state, and an avoidance of any excluded regions (e.g., region 41).
The safety risks associated with each plausible path are monitored,
and the evaluation of the safety risks for each plausible path is
used to select a target path having a substantially lowest safety
risk. Grid 20 is preferably constantly evaluated during vehicle
movement so that the target area and target path are continuously
updated, making them available immediately upon detection of an
impact event. In response to the impact, a stability control
function is initiated to autonomously steer the vehicle onto the
target path as described below. If possible, the stability control
may also stop the vehicle in the target area.
[0024] FIG. 3 shows a preferred apparatus of the invention,
including an environment monitor 50 equipped with various sensors
51 for detecting predetermined safety risks associated with the
potential destination regions around the vehicle. Based on the
sensor inputs, environment monitor 50 evaluates a plurality of
hazards which are recorded in a hazard block 52 and which are
correlated with respective regions of grid 20. Based on the
evaluation of hazards 52 in grid 20, a target area is selected and
then is identified to a path determination unit 53. A plurality of
plausible paths 54 are assembled within path determination unit 53
and the safety risks associated with each path are monitored based
on information from sensors 51 and a plurality of vehicle sensors
55 (which can be used to determine the maneuverability of the
vehicle, for example). The one of the plausible paths that has a
lowest safety risk is selected as a target path, and the target
path is identified to a post-impact path assist controller 56. An
impact detector 57 is coupled to controller 56 and provides a
triggering signal when it detects an impact between the vehicle and
another object. Controller 56 does nothing with the
continuously-generated target path information until an impact is
detected. At that time, controller 56 interacts with a stability
control 58 for autonomously steering the vehicle onto the target
path.
[0025] A general method of the invention is shown in FIG. 4 wherein
the environment in the vicinity of the vehicle is monitored for
predetermined safety risks in step 60. Risks are assigned to
regions in the grid in step 61. In step 62, the region having
substantially the lowest safety risk is selected as a target area.
In step 63, all plausible paths between the vehicle and the target
area are found, and the path having a lowest associated safety risk
is selected as a safest path in step 64. A check is performed in
step 65 to determine whether an impact has been detected. If there
has been no impact, then a return is made to step 64 in order to
substantially continuously evaluate the vehicle surroundings and to
update the target area and target path. Once an impact is detected,
the vehicle autonomously follows the safest path (or assists the
driver in the driver's efforts to follow the path) in step 66. In
step 67, if the stability control actuator is able to stop the
vehicle in the target area, then it preferably does so. After step
66, the method may also preferably return to step 60 to continue
monitoring the environment in order to reselect a target area and
safest path as the risk situation may change in the aftermath of
the collision.
[0026] FIG. 5 shows an embodiment of the invention in greater
detail. A post-impact path assist controller 70 may be coupled with
a yaw rate sensor 71, speed sensors 72 (e.g., for both vehicle and
individual wheel speeds), lateral acceleration sensor 73, vertical
acceleration sensor 74, roll rate sensor 75, steering angle sensor
76, longitudinal acceleration sensor 77, pitch rate sensor 78,
steering angle position sensor 79, and load sensor 80. A GPS
navigation system with a digital map 81 is also connected to
controller 70 as a potential source of safety risk information
(e.g., location of fixed obstructions or topology). Safety risk
information from offboard sources may also be obtained via a
wireless link 82 for coupling controller 70 with a
vehicle-to-vehicle (V2V) communication system 83 or a cloud-based
infrastructure 84.
[0027] The vehicle further contains a passive safety system 85 with
a plurality of object detection sensors 86 such as radar, lidar, or
vision-based remote sensors. Safety system 85 further includes
passive countermeasures 87, such as air bags, and collision
detection sensors 88 (which may be comprised of dedicated sensors
such as accelerometers or may include selected ones of sensors
71-80) to control deployment of countermeasures 87.
[0028] The stability control system of the present invention may
include a brake controller 90, an engine or powertrain control
module (PCM) 99, a suspension controller 100, and/or a steering
controller 101. As known in the art, brake controller 90 may
individually control brake actuators 91-94 at individual wheels to
achieve a brake-steer function and to eventually bring the vehicle
to a full stop. Brake controller 90 may preferably be shared with
other stability control systems such as an ABS system 95, a YSC
system 96, a TCS system 97, and an RSC system 98.
[0029] In operation, objects and other safety risks associated with
regions around the vehicle are identified and tracked by object
detection sensors 86 and are plugged into a grid by controller 70.
After identifying a lowest risk area, controller 70 determines
plausible paths for reaching the target area by evaluating current
vehicle speed and a maximum yaw in order to determine the maximum
amount of brake-steer that can be obtained, for example. When a
collision is detected by sensors 88, controller 70 activates one of
the stability controls such as brake controller 90 in order is to
put the vehicle onto the previously identified target path and
potentially stops the vehicle in the target area.
* * * * *