Abstract:
A lane change assist system and method are provided for assisting the driver of the vehicle in maneuvering a lane change. The system includes a range sensor mounted on a vehicle for sensing range to an object in a side detection zone adjacent to one side of the vehicle. The system also includes a controller for determining when the side detection zone is clear for the vehicle to change lanes based on the sensed range signal. The controller determines whether there is sufficient space to initial a lane change maneuver based on the sensed range signal and generates an output signal indicative thereof. An output is provided to warning lights indicative of the determined state for initiating the lane change maneuver.

Description:
TECHNICAL FIELD  
       [0001]     The present invention generally relates to object detection and, more particularly, to detecting objects in a lane adjacent to a vehicle and assisting the driver of the vehicle to maneuver a lane change.  
       BACKGROUND OF THE INVENTION  
       [0002]     Automotive vehicles are increasingly being equipped with collision warning systems that warn the driver of the host vehicle of objects (e.g., other vehicles) that may pose a potential obstruction to the host vehicle. Vehicles are typically also equipped with exterior mounted side view mirrors for viewing a portion of the side of the host vehicle. It should be appreciated that many vehicles exhibit unviewable areas in the mirrors which are commonly referred to as a blind spot regions.  
         [0003]     Drivers of longer vehicles, such as heavy duty commercial trucks and light duty trucks towing a trailer, can have difficulty judging when the destination lane is sufficiently clear to perform a lane change maneuver. Given the large distance between the driver seat and the rear end of longer vehicles, it can be quite difficult to view and judge the distance via the side view mirrors to the rear of the truck and the distance to objects in the adjacent lane. Thus, it may become difficult for the driver of such vehicles to ascertain the presence of an obstacle in the lane to which the vehicle is maneuvering.  
         [0004]     A number of detection systems have been proposed for detecting the presence of object(s) in a vehicle blind spot region and alerting the driver of the detected object(s). One example of a detection system for detecting objects emitting thermal radiation in a blind spot of a vehicle is disclosed in U.S. patent application No. 10/407,507, filed Apr. 5, 2003, and entitled “OBJECT DETECTION FOR A STOPPED VEHICLE,” the entire disclosure of which is hereby incorporated herein by reference. Another example of a proposed detection system for detecting object(s) in a blind spot of a vehicle is disclosed in U.S. Pat. No. 5,668,539, which is also hereby incorporated herein by reference. The aforementioned detection approaches employ infrared sensors, such as thermopile sensors, to detect thermal emitting objects in a blind spot region of the host vehicle.  
         [0005]     Another proposed technique for detecting object(s) in the vehicle blind spot region of the adjacent lane employs video imaging cameras mounted on the host vehicle to capture video images of the adjacent lane next to the host vehicle. The captured video images are then displayed on an onboard display monitor in the vehicle. Such conventional camera-based detection systems are generally expensive and suffer a number of drawbacks. Additionally, conventional blind spot detection systems generally focus on the blind spot region and do not provide other information on detected objects, particularly those outside the blind spot region.  
         [0006]     It is therefore desirable to provide for a cost-effective and easy to employ system for assisting the driver of a vehicle to easily and unobstructively maneuver a lane change. In particular, it is desirable to provide for a lane change assist system and method that enables the driver of a long vehicle, such as a commercial vehicle having a trailer, to maneuver the vehicle into adjacent lanes. It is further desirable to provide for such a system that is easy for a consumer to install and use.  
       SUMMARY OF THE INVENTION  
       [0007]     In accordance with the teachings of the present invention, a lane change assist system and method are provided for assisting the driver of the vehicle in maneuvering a lane change. The system includes a range sensor mounted on a vehicle for sensing range to an object in a side detection zone adjacent to one side of the vehicle. The system also includes a controller for determining when the side detection zone is clear for the vehicle to change lanes based on the sensed range signal. The controller determines whether the adjacent lane is sufficiently clear to initiate a lane change maneuver based on the sensed range signal, and generates an output signal indicative thereof. An output is provided for outputting the output signal indicative of the determined state for initiating the lane change maneuver.  
         [0008]     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  
       [0009]     The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:  
         [0010]      FIG. 1  is a top schematic view of a commercial vehicle (e.g., semi-truck) equipped with a lane change assist system according to the present invention;  
         [0011]      FIG. 2  is an exploded view of the lane change assist system mounted on an exterior rearview mirror of the vehicle;  
         [0012]      FIG. 3  is a block diagram illustrating the lane change assist system of the present invention;  
         [0013]      FIG. 4  is a flow diagram illustrating a calibration procedure for calibrating the lane change assist system; and  
         [0014]      FIG. 5  is a flow diagram illustrating a routine for executing the lane change assist processing of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]     Referring to  FIGS. 1-3 , a vehicle lane change assist system  20  is shown employed on the exterior rearview mirror housings of a commercial vehicle  10 , according to one embodiment of the present invention. The vehicle  10  may include a commercial vehicle, such as a tractor and trailer semi-truck having a fifth wheel tow hitch  14  adapted to trailer a cargo trailer  12 , according to one embodiment. According to other embodiments, the vehicle  10  may include a box truck or recreational vehicle (RV). The lane change assist system  20  may be used onboard other types of vehicles  10  as well as passenger vehicles, according to further embodiments.  
         [0016]     The lane change assist system  20  is mounted on the side of the vehicle  10  to detect the presence of one or more objects in a side detection zone  34  in a lane adjacent to the side of the host vehicle  10 . The side detection zone  34  is intended to cover the adjacent lane on the roadway. The system  10  also senses range (i.e. distance) to the detected object and determines whether the side detection zone  34  is sufficiently clear of obstacles to initiate a lane change maneuver based on the sensed range to any detected object(s). The system  10  further provides an output indicator for indicating to the driver of the host vehicle  10  whether the side detection zone  34  is sufficiently clear to change lanes.  
         [0017]     The lane change assist system  20  is shown in  FIGS. 1 and 2  mounted to the exterior side view mirror housings  16  and  18  of the host vehicle  10  according to one embodiment. A first lane change assist system  20  is mounted to the passenger (right) side side view mirror housing  16  for assisting with right lane maneuvers. A second lane change assist system  20  is mounted to the driver (left) side rearview mirror housing  18  for assisting with left lane maneuvers.  
         [0018]     Lane change assist system  10  is shown in  FIG. 2  mounted via mounting brackets  32  to the lower side housing of side view mirror  16 , according to one embodiment. Brackets  32  may include any known fastening mechanism. It should be appreciated that alternative mounting arrangements may be employed to mount lane change assist system  10  to the mirror housing or any other location onboard host vehicle  10  sufficient to detect range to objects in the adjacent lane. According to another embodiment, system  10  could be adhered to the front of a portion of the reflective mirror  16 .  
         [0019]     The lane change assist system  10  could be original equipment manufacturer (OEM) installed or could be an aftermarket add-on product which is easily transferable from vehicle to vehicle. Generally contained within the system housing  22  is a range finding sensor  24 , red and amber light emitting diodes (LEDs)  26  and  28 , a range setting threshold control knob  30 , and a microcontroller  40 . Also included is a mechanical angle fastening input  44  for adjusting the azimuth angle  0  and pitch angle (not shown) of the range finding sensor  24 .  
         [0020]     The range finding sensor  24  may include a laser, according to one embodiment. The laser sensor  24  should have an illumination intensity (brightness) that does not blind or otherwise harm or adversely affect drivers of other vehicles. One example of a suitable laser range finder is Impulse  100 , commercially available from Laser Technology. However, it should be appreciated that other types of range finding sensors may be employed, according to other embodiments. The range finding sensor  24  should have a sufficiently wide azimuth angle of view  0  and range of coverage. In one embodiment, sensor  24  has an angular azimuth 0 of about five to six degrees (5-6°).  
         [0021]     Referring to  FIG. 3 , the microcontroller  40  is shown receiving as inputs the setting from range threshold control knob  30  and the sensed range detected by range finding sensor  24 . The range threshold control knob  30  indicia marking range selections from ten to one hundred twenty feet, according to one example. Microcontroller  40  processes the range and threshold information and generates output signals to the pair of warning lights, shown as red LED  26  and amber LED  28 . The red warning LED  26  is activated when the adjacent lane is occupied by an object, while the amber warning LED  28  is activated when an object is detected just outside the adjacent lane warn the driver to proceed with caution. The processing may be achieved by processing a lane change assist logic routine  80  which, in one embodiment, may be implemented as executable software.  
         [0022]     The microcontroller  40  may be implemented in discrete circuitry employing volatile and non-volatile memory. According to one embodiment, microcontroller  40  may be implemented as a proportional-integral-control (PIC) microcontroller having random access memory (RAM) and erasable programmable read-only memory (EPROM). One example of a microcontroller  40  is Model No. PIC 16C781 commercially available from Microchip Corporation. Other known control circuitry including analog and digital controls may be employed as the controller for processing the range signals and activating the warning lights.  
         [0023]     The microcontroller  40  is shown powered by voltage V B  supplied by battery  42 . It should be appreciated that the battery voltage V B  can also be supplied to power the range finding sensor  24  and warning indicator LEDs  26  and  28 . The battery voltage V B  may be supplied by the vehicle battery through an electrical connection in the mirror housing or vehicle door, or may be supplied by separate battery supply.  
         [0024]     The lane change assist system  20  can be installed on the host vehicle  10  by a vehicle manufacturer or can be installed on the host vehicle  10  by a consumer or user of the vehicle  10 . The system  10  may be easily calibrated to accommodate changes in the adjacent lane side detection zone and/or changes in the length of the host vehicle  10  such as may occur when adding, removing or changing a trailer.  
         [0025]     When installed onto a host vehicle  10 , the lane change assist system  20  is initially calibrated as shown by calibration procedure  50  in  FIG. 4 , according to one embodiment. The calibration procedure  50  may be performed by the original vehicle manufacturer or may be performed by a user of the host vehicle  10 . With the lane change assist system  10  and its range finding sensor  24  mounted to the mirror housing as required in step  52 , calibration routine  50  proceeds to step  54  to place a target object, such as another vehicle  42 , at a desired longitudinal distance and lateral distance away from the host vehicle  10 . In the truck trailer embodiment, the target object may be located a buffer distance B of about five feet behind the towed trailer structure and about six feet laterally outward in the adjacent lane.  
         [0026]     With the target object in place, the range threshold control knob is set to the maximum position in step  56  and the mechanical angle fastening control knob is unlocked in step  58 . The power is then turned on in step  60  and the mechanical azimuth angle  0  and pitch angle of the range finding sensor are adjusted until the “lane occupied” red LED is activated in step  62 . Activation of the red LED indicates that the obstacle vehicle  42  is detected entering the first and most imminent side detection zone  36  in the adjacent lane, thus setting the point at which the red LED turns on. In doing so, the calibrator should ensure that the range finding sensor is not detecting the roadway (e.g., pavement) as the target object.  
         [0027]     Once the mechanical azimuth and pitch angles have been set, the mechanical angle fastening control is locked in step  64 . Thereafter, the range threshold control knob is slowly dialed down to decrease the threshold range until the red LED is deactivated and the “proceed with caution” amber LED is activated in step  66 . Activation of the amber LED indicates that the obstacle vehicle  42  is entering into the second or extended range  38 . The second range  38  is defined as the first range  36  extended by a constant distance C.  
         [0028]     Following step  66 , calibration routine  50  proceeds to step  68  of testing the calibration settings by moving the test target object. This may include moving the target object to within the first and second coverage zones  36  and  38  and monitoring activation of the corresponding warning lights  26  and  28 . Following test step  68 , routine  50  proceeds to decision step  70  to determine if the LEDs are deactivated and, if so, the calibration procedure  50  is complete in step  72 . Otherwise, if an LED is activated, calibration routine  50  returns back to step  62  to adjust the mechanical angle(s) of the range finding sensor.  
         [0029]     It should be appreciated that the calibration routine  50  may be performed when the lane change assist system  20  is first installed onto the host vehicle  10 . The calibration routine  50  could also be performed each time a modification is made to the host vehicle  10  that changes the detection range and/or angle θ of the detection zone  34 , such as adding, removing, or replacing a trailer. It should further be appreciated that the system  20  may be easily moved from one vehicle to another vehicle. Upon placing the lane change assist system  20  on a new host vehicle, the calibration procedure  50  easily may be performed by the vehicle operator as previously described.  
         [0030]     The lane change assist logic  80  is illustrated in  FIG. 5  according to one embodiment. Logic  80  begins at step  82  and proceeds to decision step  84  to determine if the vehicle power/ignition is on. If the vehicle power is not on, logic  80  waits for the vehicle power to be turned on before proceeding. Once the vehicle power is turned on, logic  80  proceeds to decision step  86  to determine if a target object is present in the range finder path. If no target object is present in the range finder path, logic  80  proceeds to deactivate both the amber and red LEDs in step  88 , and then returns to decision step  86 .  
         [0031]     If a target object is detected in the range finder path, logic  80  proceeds to decision step  90  to process the detected range to the target object. If the measured range is less than or equal to the set range threshold, logic  80  activates the lane occupied red LED and flashes the proceed with caution amber LED in step  92 . If the measured range is greater than the set range threshold, logic  80  then proceeds to decision step  94  to determine if the measured range is less than or equal to the range threshold plus constant C (e.g., five feet), which defines an extended warning range. If the measured range is less than or equal to the range threshold plus constant C, logic  80  activates the amber LED and deactivates the red LED in step  96 .  
         [0032]     The amber LED serves as a caution warning indicating that an object is not in the adjacent lane, but there is a detected object close to the adjacent lane such that the driver should proceed cautiously. If the measured range is greater than the range threshold plus constant C, logic  80  deactivates both the amber and red LEDs in step  88 . Logic  80  continually monitors for the presence of target object(s) and the range to the target object(s), until the vehicle power/ignition is turned off.  
         [0033]     Accordingly, the warning indicator LEDs serve to warn the driver of the host vehicle  10  of the presence of an object in the corresponding adjacent lane. The red LED is activated when an object is detected in the adjacent lane side detection zone  34 . When the object is no longer in the adjacent lane side detection zone, but is in an extended zone, the amber LED is activated to serve as a cautionary warning. When no objects are detected in either of the primary detection zone and extended cautionary zone, both LEDs are turned off. As another vehicle approaches the side of the host vehicle  10 , the warning indicator activation may change from no LEDs to the amber LED, to the red LED, which the driver may easily monitor to assist in maneuvering lane changes.  
         [0034]     In contrast to conventional blind spot detection systems which detect the presence or absence of an object in a blind spot region, the lane change assist system  20  of the present invention quantifies the distance to a detected object that is present in a side detection zone adjacent to the vehicle  10 . The detection zone may include a region that is visible in a side view mirror to the driver of the vehicle  10  and, hence, is outside of the blind spot region. While the presence of an object in the side detection zone may be viewable to the driver via a mirror, a determination of whether the object is far enough behind the host vehicle to allow the driver to change lanes is provided by the lane change assist system  20  of the present invention. Thus, the lane change assist system  20  serves as a driver&#39;s aid in judging whether the adjacent lane is available for a lane change maneuver.  
         [0035]     Accordingly, the lane change assist system  20  of the present invention advantageously provides a warning indicator to the driver of the host vehicle  10  to assist in maneuvering a lane change. The system  20  is cost-effective, easy to install, and easy to use. The system  20  is further easily calibratable by a consumer or user and may be used on any of a number of vehicles.  
         [0036]     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.