Abstract:
A vehicle lane departure warning system and method are provided having a trailer mode. The system includes an imager capturing images of a roadway forward of a vehicle and an input receiving a towing signal indicative of whether the vehicle is towing a trailer. The system also includes a processor for processing the captured images and determining whether the vehicle or trailer is expected to be departing from a lane on the roadway based on the captured images and a threshold width value. The processor selects the threshold width value based on the input towing signal such that an enhanced threshold width value is employed when the vehicle is towing a trailer. An output is provided for outputting a lane departure warning signal based on the processed images and selected threshold width value.

Description:
TECHNICAL FIELD 
       [0001]    The present invention generally relates to lane departure warning for a vehicle, and more particularly relates to detection and warning of a lane departure for a vehicle towing a trailer having a width wider than the tow vehicle. 
       BACKGROUND OF THE INVENTION 
       [0002]    Lane departure warning (LDW) systems have been developed for vehicles to detect and warn of the vehicle&#39;s departure from a lane on a roadway. The LDW system typically employs one or more camera based vision systems mounted to the host vehicle which generate digital images of the roadway and lane markings forward of the vehicle. This may be achieved by monitoring the position of the vehicle relative to the lane boundary markings found on the roadway. A typical roadway may have a lane width of one about hundred forty-six (146) inches, as compared to conventional light duty host vehicle widths which are usually less than eighty (80) inches. The conventional proposed LDW systems typically calculate vehicle lane departure based on the width of the host vehicle. Typically, camera images are processed into scenes by a microprocessor to determine whether the vehicle is expected to be departing from the lane of the roadway based on processed image algorithms and a threshold width value, which typically is based on the width of the host vehicle. 
         [0003]    While the currently proposed lane departure warning system may serve adequately well to determine departure of a vehicle from the roadway, limitations or drawbacks exist when the vehicle is towing a trailer, particularly, a trailer having a width wider than the host driving vehicle. For example, a trailer may have a width of one hundred two (102) inches, which is substantially greater than the width of the host vehicle. The conventional proposed LDW system operates based on the width of the host vehicle and may not adequately detect when the trailer first departs from the lane due to its extended width. The large discrepancy between the host vehicle width and the trailer width allows the trailer to depart from the lane before the conventional proposed LDW system may alert the driver of such an event. 
         [0004]    Accordingly, it is therefore desirable to provide for an enhanced lane departure warning system that effectively detects the departure of the vehicle and its towed trailer from a lane on a roadway and does not suffer from the drawbacks or limitations of the conventional proposed LDW systems. 
       SUMMARY OF THE INVENTION 
       [0005]    According to one aspect of the present invention, a vehicle lane departure warning system having a trailer mode is provided. The system includes an imager capturing images of a roadway proximate to a vehicle and an input receiving a towing signal (manual) indicative of whether the vehicle is towing a trailer. The system also includes a processor processing the captured images and determining whether the vehicle or trailer is expected to be departing from a lane on the roadway based on the captured images and a threshold width value, wherein the processor further selects the threshold width value based on the input towing signal (manual) such that an enhanced threshold width value is employed when the vehicle is towing a trailer. The system further includes an output for outputting a lane departure warning signal based on the processed images and selected threshold width value. 
         [0006]    According to another aspect of the present invention, a method of detecting a vehicle departing from a lane on a road with a trailer mode is provided. The method includes the steps of capturing images of the roadway proximate to the vehicle, and processing the captured images to determine whether the vehicle or a trailer is expected to be departing from a lane on the roadway based on the captured images and a threshold width value. The method also includes the step of monitoring an input to detect a towing signal indicative of whether the vehicle is towing a trailer. The method further includes the steps of selecting the threshold width value based on the towing signal such that an enhanced threshold width value is employed when the vehicle is towing a trailer, and outputting a lane departure warning signal based on the processed images and the selected threshold width value. 
         [0007]    These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
           [0009]      FIG. 1  is a schematic top view of a vehicle towing a trailer in a lane of a roadway and employing a lane departure warning system, according to one embodiment; 
           [0010]      FIG. 2  is a block diagram of the lane departure warning system according to one embodiment; and 
           [0011]      FIG. 3  is a flow diagram illustrating a routine employed in the lane departure warning system for detecting vehicle lane departure with a trailer mode, according to one embodiment. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0012]    Referring now to  FIG. 1 , an automotive wheeled host vehicle  10  is generally illustrated having a trailer hitch  14  towing a trailer  12  within a lane  18  on a roadway  16 . The host tow vehicle  10  is shown having a vehicle width W V  as compared to a larger or extended trailer width W T . The trailer  12  may be connected to the vehicle  10  via any of a number of tow hitches, such as a fifth wheel hitch, in a trailer tow mode and may be disconnected from the vehicle  10  such that the vehicle  10  may operate in a non-trailer tow mode without the trailer  12 . The roadway  16  has one or more lanes  18  shown defined by lane boundary markings and each lane  18  has a lane width W L . 
         [0013]    The host vehicle  10  is equipped with a lane departure warning system  20  for detecting departure of the host vehicle  10  and its trailer  12  from the lane  18  of the roadway  16 . The lane departure warning system  20  advantageously detects lane departure of the host vehicle  10  and its enlarged width trailer  12  in a trailer tow mode. The lane departure warning system  20  employs one or more camera imaging devices  22 , shown located near the front of the host vehicle  10 , for capturing images of the roadway  16  forward of the vehicle  10 . The captured images are processed to detect and determine the boundary markings of the lane  18  and to determine whether the host vehicle  10  and/or its trailer  12  depart from lane  18 . If a lane departure is detected, the system  20  generates a lane departure warning output. It should be appreciated that the lane departure warning system  20  is configured to provide a lane departure warning sufficient to detect departure of the extended width trailer  12  from lane  18  when the host vehicle  10  is operated in the trailer tow mode. 
         [0014]    Referring to  FIG. 2 , the lane departure warning system  20  is illustrated employing a lane departure warning (LDW) controller  26 . The controller  26  may include a controller dedicated to vehicle lane departure detection and warning according to one embodiment, or may be integrated with other vehicle control systems according to other embodiments. The lane departure warning controller  26  includes control circuitry shown as a microprocessor  30  and memory  32 . Microprocessor  30  may include analog and/or digital control circuitry, according to various embodiments. Memory  32  may include random access memory (RAM), read-only memory (ROM), electronically erasable programmable read-only memory (EEPROM), flash memory and other known memory devices. Stored within memory  32  and executed by the microprocessor  30  is a LDW trailer mode routine  50  and two or more threshold width values  34 . The routine  50  processes the captured images of the roadway  16  forward of the host vehicle  10  and determines whether the host vehicle  10  and/or trailer  12  is departing from a lane  18  on the roadway  16  based on a selected one of the threshold width values  34 . 
         [0015]    The lane departure warning system  20  employs one or more cameras  22  for providing generated images as an input to the LDW controller  26 . Additionally, the lane departure warning system  20  has a towing input  24  for providing an input towing signal to the LDW controller  26 . The input towing signal may include a signal supplied via the vehicle serial communication bus such as a CAN bus. The towing signal may be generated automatically when a trailer tow harness of the trailer  12  is connected to a tow harness of the host vehicle  10  indicating that the vehicle  10  is towing a trailer  12 , according to one embodiment. According to another embodiment, the towing input  24  may include a discrete towing signal generated in response to an operator of the host vehicle  10  manually actuating a switch or other input to select a trailer tow mode. According to a further embodiment, the towing input  24  may include a user entered trailer width input  25  that may allow the user to input one or more signals that select from a plurality of different threshold width values for different width size trailers, which may be provided by way of a human machine interface (HMI) (e.g., menu based multi-mode switch). For example, a user may have one threshold width value from available threshold width values that corresponds to different trailer widths such as widths of ninety-two (92) inches or one hundred two (102) inches. 
         [0016]    The lane departure warning system  20  further includes an output warning signal  28 . The output warning signal  28  may include an audible alarm intended to quickly alert the driver of the vehicle  10  of the detected departure of the host vehicle  10  and/or its trailer  12  from the lane of the roadway. The output warning signal  28  could include other outputs, such as a visual display, a haptic output, such as a vibrating seat, serial communications data scheme, or other warning outputs. It should further be appreciated that the lane departure output warning signal  28  may be provided to other systems for use in other applications onboard the vehicle  10 , such as collision avoidance, as should be evident to those skilled in the art. 
         [0017]    In operation, the lane departure warning system  20  receives video images captured by the camera  22  generally forward of the host vehicle  10  which include the lane boundary markings defining the lane  18  of the roadway  16  such that the relative position of the vehicle  10  and its trailer  12  relative to the lane  18  can be determined. The captured images are processed to determine whether the host vehicle  10  and/or its trailer  12  is expected to be departing from the lane  18  on the roadway  16  based on the captured images and a selected threshold width value. Normally, in a non-trailer tow mode without a trailer, the threshold width value is based on the width W V  of the vehicle  10 . The lane departure warning system  20  further selects the threshold width value based on the towing signal such that an enhanced threshold width value is employed when the host vehicle  10  is towing a trailer  12  in the trailer tow mode. Thus, the width W T  of the trailer  12  is taken into consideration to allow the lane departure warning system  20  to detect when the trailer  12  has departed from the lane  18  of the roadway  16 . 
         [0018]    The lane departure warning with trailer mode routine  50  is illustrated in  FIG. 3  according to one embodiment. Routine  50  begins at step  52  and proceeds to step  54  to capture the images forward of the host vehicle with the camera. Next, at step  56 , routine  50  processes the captured video images to determine the host vehicle&#39;s relative position within a lane of the roadway. At decision step  58 , routine  50  determines whether a trailer towing signal has been detected. If no trailer towing signal has been detected, routine  50  proceeds to step  60  to select the default vehicle width threshold value, such that the lane departure warning system operates in a non-trailer towing mode. In the non-trailer tow mode, the default vehicle width threshold value is typically based on the vehicle width W V  and is used to determine lane departure. If a trailer towing signal has been detected in step  58 , routine  50  proceeds to step  62  to select the extended trailer width threshold value so as to set the routine  50  in a trailer towing mode. Accordingly, an extended width threshold value is employed in the trailer mode to determine lane departure, as compared to the non-trailer mode. It should be appreciated that multiple trailer mode extended width threshold values may be available to select from so as to accommodate different trailer widths. Once the width threshold value is set, routine  50  proceeds to decision step  64  to determine if the host vehicle and/or its trailer is departing from the current lane based on the selected threshold value and, if so, activates the LDW warning signal at step  66 . Accordingly, routine  50  advantageously selects the vehicle width threshold value from a plurality of threshold values to allow the lane departure warning system to operate in a trailer mode and a non-trailer mode with enhanced effectiveness. 
         [0019]    Routine  50  generally illustrates one embodiment of a lane departure warning routine that selects a threshold width value in a trailer tow mode. However, it should be appreciated that the principles of the present invention may apply to use in connection with other lane departure warning systems according to other embodiments. For example, the routine  50  could be modified to operate with a lane departure warning system disclosed in U.S. Pat. No. 7,050,908, which is hereby incorporated herein by reference. This may be achieved by modifying the aforementioned system to detect a trailer tow mode and select a threshold width value in response thereto. 
         [0020]    The lane departure warning system  10  advantageously improves the detection of lane departure and warning thereof for a host vehicle towing a trailer in the trailer mode. According to one example, the host vehicle having a width of 79.9 inches traveling on a two-lane roadway having a lane width of 146 inches may have approximately 33 inches on each side of the vehicle  10  before a lane departure occurs, provided the vehicle is centered in the roadway. In a non-trailer mode, the lane departure warning system  10  may provide lane departure detection and warning based on the host vehicle width of 79.9 inches. In a trailer towing mode, if the host vehicle is towing a trailer having a width of 102 inches, the lane departure warning system is reconfigured to operate with the extended trailer width threshold value based on the 102 inch width, the system advantageously recalculates the distance to lane markings based on the trailer width of 102 inches to detect when the trailer departs from the lane. 
         [0021]    It will be understood by those who practice the invention and those skilled in the art, that various modifications and improvements may be made to the invention without departing from the spirit of the disclosed concept. The scope of protection afforded is to be determined by the claims and by the breadth of interpretation allowed by law.