Abstract:
A collision avoidance system for a vehicle includes an electronic brake system capable of applying wheel brakes to decelerate the vehicle, a steering system capable of changing a steering angle for the vehicle, and a controller. The controller instructions for performing a pedestrian avoidance maneuver including at least one of steering the vehicle to the maximum available separation distance and braking the vehicle to the maximum safe speed while the vehicle is passing the pedestrian.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to U.S. Provisional Application No. 61/933,110 filed on Jan. 29, 2014. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to automotive vehicles, and more particularly to an autonomous vehicle operation system. 
       BACKGROUND 
       [0003]    Advancements in sensor technology have led to the ability to improve safety systems for vehicles. Arrangements and methods for detecting and avoiding collisions are becoming available. Such systems use sensors located on the vehicle to detect an oncoming collision. The systems may warn the driver of various driving situation to prevent or minimize collisions. Such systems are especially useful for increasing safety in vehicles which operate under autonomous or semi-autonomous conditions. 
         [0004]    The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. 
       SUMMARY 
       [0005]    A collision avoidance system for a vehicle includes an electronic brake system capable of applying wheel brakes to decelerate the vehicle, a steering system capable of changing a steering angle for the vehicle, and a controller. The controller includes instructions for detecting an object proximate to a vehicle with at least one sensor and analyzing data from the sensors with a controller to determine if the object detected is a pedestrian proximate to the vehicle. The controller further includes instructions for determining a maximum separation distance from the pedestrian while maintain the vehicle within a current lane of travel and determining a maximum safe speed for the vehicle to pass the pedestrian based upon the maximum separation distance available. The controller further includes instructions for performing a pedestrian avoidance maneuver including at least one of steering the vehicle to the maximum separation distance and braking the vehicle to a maximum safe speed while the vehicle is passing the pedestrian. 
         [0006]    Although the different examples have the specific components shown in the illustrations, embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. 
         [0007]    These and other features disclosed herein can be best understood from the following specification and drawings, the following of which is a brief description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0009]      FIG. 1  is a schematic illustration of a top view of a vehicle utilizing a safety system of the present invention; 
           [0010]      FIG. 2  is an example relationship between speed and distance from an object; 
           [0011]      FIG. 3  is a graphical illustration of an example step of a disclosed method of for passing a pedestrian; 
           [0012]      FIG. 4  is a graphical illustration of another example step of the disclosed method for passing a pedestrian. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The following description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements.  FIG. 1  illustrates a vehicle  10  and a driver assistance system, in particular a collision avoidance system  12  that may be used to brake and/or steer a vehicle  10  during autonomous and semi-autonomous vehicle operations. 
         [0014]    The collision avoidance system  12  may include a camera  30  mounted to provide a view of a driving direction for the vehicle  10 . The camera  30  may be a monocular camera, binocular camera, or another type of sensing device capable of providing a view of the proximate area around and the travelling path of the vehicle  10 . A controller  18  may be connected to the camera  30  to analyze the image/data and identify objects  34  within the image that may be obstacles for the vehicle  10 . In addition to the camera  30  the collision avoidance system  12  may use other systems and sensors to assist in identifying objects  34 . Such systems and sensors may include, but are not limited to: proximity sensors  36 , LIDAR, RADAR, ultrasound, GPS  38 , radio sensors, a power steering system  14 , and an electronic brake system (EBS)  16 , etc. A common or separate controller  18  may be used by the systems  12 ,  14 ,  16 . 
         [0015]    The collision avoidance system  12  determines when a braking and/or steering event needs to occur, whether the vehicle  10  is travelling in a forward or a reverse direction, to avoid an object and/or a pedestrian. The collision avoidance system  12 , steering system  14 , EBS  16 , or a similar system determines a probability of collision when an obstacle is detected. If the probability of collision is above a predetermined threshold, at least one vehicle collision avoidance action is provided. The collision avoidance action can include actuation of a warning to alert a driver when an obstacle is detected and/or modification of a vehicle speed or current path to avoid the obstacle. 
         [0016]    Referring to  FIG. 2  with continued reference to  FIG. 1 , graph  40  illustrates a relationship between vehicle speed  48  and distance from an identified object  34 . A safe zone  46  is separated from an unsafe zone depending on velocity  42 . A boundary  58  provides a graphical illustration of the relationship between an acceptable separation distance  44  for a current velocity  42 . As velocity of the vehicle increases, the safe distance from the identified object also increases. As the velocity  42  decreases, the acceptable safe distance from the object  34  decreases. Accordingly, upon approaching an object, the vehicle  10  may either reduce velocity or increase lateral distance from the object. 
         [0017]    If the system  12  detects that a collision with an obstacle seems likely, one avoidance action may be to use the EBS  16  to apply the brakes  20  to prevent the collision and/or the steering system  14  to steer the vehicle  10  away from the obstacle. For example, the collision avoidance system  12  may detect and identify an object as a pedestrian. In such situations, safety can be increased when passing a roadside pedestrian during autonomous vehicle operation by adjusting the lateral separation and vehicle speed. 
         [0018]    Referring to  FIG. 3  with continued reference to  FIG. 1 , upon detecting a pedestrian  34  alongside or in the current lane, the vehicle  10  first adjusts its lateral position  50  to provide maximum separation distance indicated at  50  in graph  52  from the pedestrian without incurring additional danger from oncoming traffic or vehicles in adjacent lanes. As appreciated, lateral movement of the vehicle within a given lane is limited and therefore at some vehicle speeds  42  lateral movement as indicated at  50  is not sufficient to create an acceptable lateral separation distance from the pedestrian given the vehicles current speed. 
         [0019]    Referring to  FIG. 4 , with continued reference to  FIGS. 2 and 3 , if sufficient separation distance is not available to move to the boundary  58 , then the speed may be decreased. In this example, the vehicle speed exceeds the acceptable limit for the available separation distance. Accordingly, when the speed is determined to be too high for the lateral separation  50 , the vehicle  10  is automatically slowed down an amount indicated at  56  in graph  54  before passing the pedestrian. The amount that the speed is reduced is dependent on the separation distance  50  available to the vehicle  10 . For lesser separations distances  50 , a greater reduction in vehicle speed  56  would be implemented. After the pedestrian  34  has been passed, the vehicle  10  can re-center itself in the lane and resume the previous speed. 
         [0020]    Referring to  FIG. 1 , a first path  60  is shown that represents a vehicle path required to maintain a desired distance with minimal reduction to speed. A second path  62  is shown that relies only on reducing velocity to bring the vehicle to desired operating condition for passing the pedestrian  34 . An “effective lane boundary”  64  is determined based on a set of predefined criteria that considers current road usage restrictions and requirements such as for example, if local rules allow a solid lane boundary be crossed and what minimum separation is desired between vehicles in an adjacent lane. 
         [0021]    Once the vehicle  10  has moved laterally to the edge of the effective lane  64 , the collision avoidance system  12  may additionally slow the vehicle  10  based on the determined current relationship as is illustrated in  FIGS. 2 ,  3  and  4 . The maximum speed of the vehicle is determined based on the expected classification in the two regions shown in the  FIG. 2 . The slope and offset of the classification boundary  58  is determined based on prior studies of pedestrian behavior. If the vehicle  10  has already planned to shift laterally to the limit (d limit ), it can additionally lower the speed of the vehicle by Δv until the safe zone  46  is reached. 
         [0022]    Being proactive in such a situation by steering away within the lane and minimizing speed if necessary mimics a human driver&#39;s behavior and helps minimize the risk associated with unexpected pedestrian actions. For example, it may appear that given the trajectory of a cyclist, a collision won&#39;t occur, but perhaps the cyclist is unaware of the approaching vehicle  10  and shifts laterally into the vehicle&#39;s path. Additionally, a pedestrian  34  could always trip and fall into the path of a vehicle  10 . By taking into account these scenarios ahead of time, the vehicle  10  can avoid unexpected pedestrian actions. 
         [0023]    While the best modes for carrying out the invention have been described in detail, the true scope of the disclosure should not be so limited, since those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.