Patent Publication Number: US-2019187719-A1

Title: Emergency lane change assistance system

Description:
TECHNICAL FIELD 
     The present invention relates generally to vehicle systems and, more specifically, relates to a system for helping the host vehicle to respond to the presence of an emergency vehicle. 
     BACKGROUND 
     Current driver assistance systems (ADAS—advanced driver assistance system) offer a series of monitoring functions in vehicles. In particular, the ADAS can monitor the environment around the vehicle and notify the driver of the vehicle of conditions therein. To this end, the ADAS can capture images of the surrounding environment and digitally process the images to extract information. The later information is used to warn the driver of road obstacles located along the driving path. Common ADAS systems include automatic emergency braking (AEB) to help prevent rear-end collision and adaptive cruise control (ACC) to help mitigate pre-set vehicle speed to keep a safe distance from a following vehicle. ADAS systems can also include lane detection (LD) to help maintain the vehicle within the intended driving lane. 
     SUMMARY 
     In one aspect of the present invention, a method of autonomously assisting the operation of a host vehicle traveling on a first lane of a roadway includes detecting the presence of an emergency vehicle along the roadway by identifying the warning light patterns. The distance between the host vehicle and one of the emergency vehicle and a stationary vehicle associated with the emergency vehicle is monitored. A steering gear is actuated to laterally move the host vehicle out of the first lane into a pre-determined object-free space that is parallel to the host vehicle, when the distance between the host vehicle and one of the emergency vehicle and the stationary vehicle reaches a predetermined value. The longitudinal motion of the vehicle is also controlled by the vehicle power train and/or braking module to bring the vehicle to a calculate speed that is deemed safe before the lateral motion is initiated to deliver the host vehicle into the object-free space. 
     In another aspect of the invention, a system for autonomously assisting the operation of a host vehicle traveling on a first lane of a roadway includes at least one camera assembly for detecting the presence of an emergency vehicle along the roadway. A proximity sensor monitors the distance between the host vehicle and one of the emergency vehicle and an associated stationary vehicle. A controller connected to the at least one camera assembly and the proximity sensor actuates a steering gear to laterally move the host vehicle out of the first lane when the distance between the host vehicle and one of the emergency vehicle and the stationary vehicle reaches a predetermined value. 
     Other objects, advantages and a fuller understanding of the invention will be outlined in the following detailed description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of a host vehicle having an assist system in accordance with an embodiment of the present invention. 
         FIG. 2  is a schematic illustration of the assist system of  FIG. 1 . 
         FIG. 3  is a schematic illustration of the host vehicle traveling in a first lane of a roadway and detecting an emergency vehicle in a first condition. 
         FIG. 4  is a schematic illustration of the host vehicle of  FIG. 3  switching to a second lane of the roadway. 
         FIG. 5  is a schematic illustration of the host vehicle of  FIG. 3  passing the emergency vehicle. 
         FIG. 6  is a schematic illustration of the host vehicle of  FIG. 3  returning to the first lane. 
         FIG. 7  is a schematic illustration of the host vehicle traveling in a first lane of a roadway and detecting an emergency vehicle in a second condition traveling behind the host vehicle. 
         FIG. 8  is a schematic illustration of the host vehicle of  FIG. 7  pulling over to the side of the roadway. 
         FIG. 9  is a schematic illustration of the host vehicle traveling in a first lane of a roadway and detecting an emergency vehicle in a third condition behind the host vehicle. 
         FIG. 10  is a schematic illustration of the host vehicle of  FIG. 9  switching to the second lane of the roadway to allow the emergency vehicle to pass. 
         FIG. 11  is a schematic illustration of the emergency vehicle passing the host vehicle of  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION 
     The present invention relates generally to vehicle systems and, more specifically, relates to a system for helping a vehicle respond to the presence of an emergency vehicle.  FIG. 1  illustrates a host vehicle  20  having an assist system  80  in accordance with an embodiment of the present invention. 
     The host vehicle  20  extends along a centerline  22  from a front end  24  to a rear end  26 . The host vehicle  20  includes a left side  27  and a right side  29  positioned on opposite sides of the centerline  22 . The left side  27  includes a pair of doors  28   a ,  28   b  each having an associated window  30   a ,  30   b . The right side  29  includes a pair of doors  32   a ,  32   b  each having an associated window  34   a ,  34   b.    
     The front end  24  of the host vehicle  20  includes a front window or windshield  40  extending generally between the left and right sides  27 ,  29 . The rear end  26  of the host vehicle  20  includes a rear window  42  extending generally between the left and right sides  27 ,  29 . The windows  30   a ,  30   b ,  32   a ,  32   b ,  40 ,  42  and doors  28   a ,  28   b ,  32   a ,  32   b  collectively help define an interior  54  of the host vehicle  20 . The exterior of the host vehicle  20  is indicated generally at  56 . 
     The host vehicle  20  includes a pair of front steerable wheels  60  and a pair of rear wheels  62 . The front wheels  60  are mechanically linked to a steering actuator or gear  68  (see  FIG. 2 ), which is mechanically linked to a steering wheel  66 . Alternatively, the front wheels  62  and steering wheel  66  could be part of a steer-by-wire system (not shown). The rear wheels  62  could also be coupled to the steering wheel  66  by the same steering gear  68  or another steering gear (not shown). 
     In any case, rotation of the steering wheel  66  actuates the steering gear  68  to turn the wheels  60  relative to the centerline  22  in order to steer the host vehicle  20 . To this end, the steering wheel  66  has a neutral position in which the wheels  60  point in directions that are parallel to the centerline  22  such that the host vehicle moves in a straight line. Counterclockwise rotation of the steering wheel  66  angles the wheels  60  leftward relative to the centerline  22  (as shown in  FIG. 1 ), causing the host vehicle  20  to turn left. Clockwise rotation of the steering wheel  66  angles the wheels  60 ,  62  rightward relative to the centerline  22 , causing the host vehicle  20  to turn right. 
     The assist system  80  includes a surround view system  18  for capturing images of the host vehicle exterior  56 . The surround view system  18  includes camera assemblies  70   a - 70   h  provided around the periphery of the host vehicle  20 . As shown, camera assemblies  70   a - 70   c  are secured to the front end  24  of the host vehicle  20  along or adjacent to the centerline  22 . A camera assembly  70   d  is secured to the rear end  26  of the host vehicle  20  along or adjacent to the centerline  22 . A pair of camera assemblies  70   e - 70   f  is secured to the left side  27 . A pair of camera assemblies  70   g - 70   h  is secured to the right side  29 . All the camera assemblies  70   a - 70   h  face outward away from the host vehicle  20 . It will be appreciated that more or fewer camera assemblies can be provided. In any case, all of the camera assemblies  70   a - 70   h  are electrically or wirelessly connected to a controller  76  in the host vehicle  20 . 
     Each camera assembly  70   a - 70   h  has an associated field of view  72   a - 72   h  covering a portion of the host vehicle exterior  56 . Collectively, the fields of view  72   a - 72   h  encircle the entire vehicle  20  and overlap one another. The controller  76  continuously receives images taken by the camera assemblies  70   a - 70   h  within the respective fields of view  72   a - 72   h . The controller  76  includes an image processing module (not shown) that receives and analyzes the data associated with the images from the camera assemblies  70   a - 70   h . The controller  76  can, for example, stitch the images together to form a 360° surround view (not shown) of the host vehicle exterior  56 . The images can also be relied on to identify objects around the host vehicle  20 . 
     Referring to  FIG. 2 , the controller  76  is also electrically or wirelessly connected with various sensors and actuators in the host vehicle  20  for monitoring and controlling several functions of the host vehicle, namely, vehicle speed and steering. To this end, the controller  76  is electrically or wirelessly connected to a vehicle speed sensor  100 . The speed sensor  100  monitors the host vehicle speed and generates an electrical signal  102  indicative thereof that is sent to the controller  76  at predetermined time intervals. 
     The controller  76  is also electrically or wirelessly connected to an actuator  110  associated with the vehicle brake  112  and a throttle actuator  120  associated with the gas pedal  122 . The controller  76  can send a control signal  114  to the brake actuator  110  to decrease the host vehicle  20  speed. The controller  76  can send a control signal  124  to the throttle actuator  120  to increase the host vehicle  20  speed. 
     A wheel position sensor  150  monitors the rotational angle of the steering wheel  66  and generates an electrical signal  152  indicative of the steering angle. The signal  152  is sent to the controller  76  at predetermined time intervals. The controller  76  can send a control signal  142  to the steering gear  68  in response to the wheel position signal  152 , thereby controlling rotation of the steering wheel  66 . The steering gear  68  actuation also controls the steering angle of the front wheels  60  relative to the centerline  22  of the host vehicle  20 . 
     At least one proximity sensor  130  is electrically or wirelessly connected to the controller  76  for acquiring data related to objects around the host vehicle exterior  56 . The at least one proximity sensor  130  can include, for example, laser scanners, ultrasonic sensors, radar detectors, and LIDAR detectors, for determining and monitoring the distance between the host vehicle  20  and objects around the host vehicle exterior  56  detected by the camera assemblies  70   a - 70   h.    
     Based on this construction, the controller  76  is capable of receiving continuous feedback regarding the driving conditions of the host vehicle, e.g., vehicle speed and steering angle, images around the host vehicle exterior  56 , and the distance between the host vehicle and objects identified in the images. The controller  76 , in response to these inputs, is capable of controlling vehicle operation in a manner that helps increase occupant safety. More specifically, the controller  76  is capable of autonomously controlling the host vehicle  20  position (lateral motion) and/or speed (longitudinal motion) in response to detecting the presence of an emergency vehicle. 
     A turn signal  154  constituting a lever or button is electrically or wirelessly connected to the controller  76  for notifying other vehicles when the host vehicle  20  intends to changes lanes  202 ,  204  or move onto/off the roadway  200 . To this end, the controller  76  automatically sends a signal  156  to the turn signal  154  before and/or while the host vehicle  20  laterally moves along, onto or off the roadway  200 . In response, the turn signal  154  will actuate lights (not shown) on the host vehicle  20  indicating the intended direction of lateral movement of the host vehicle. 
     An alert  160  is electrically or wirelessly connected to the controller  76  for providing feedback to the operator of the host vehicle  20  before and/or while autonomous operations are performed by the assist system  80 . The alert  160  provides visual, audio or haptic feedback to the operator before and/or when the controller  76  sends a signal  162  thereto. 
     In one example, the assist system  80  helps the host vehicle  20  maintain a safe distance from an emergency vehicle stopped along the side of a roadway and any stationary vehicles associated therewith. “Emergency vehicle” as described herein includes public safety vehicles, traditional emergency vehicles, and road service vehicles. Example emergency vehicles can include ambulances, tow trucks, fire trucks, police vehicles, snow plows, etc. 
     An example roadway  200  is shown in  FIG. 3  and has a direction of vehicle travel illustrated by the arrow T. The roadway  200  includes a series of lanes  202 ,  204  separated by a dashed dividing line  206 . Additional lanes and dividing lines are contemplated but not shown. The roadway  200  is defined from the surrounding off-road terrain  210  by a boundary line  214  on the left side (relative to the traveling direction T) and by a boundary line  216  on the right side. 
     In  FIG. 3 , the host vehicle  20  travels within the lane  204  in the direction T. The emergency vehicle  300  is shown pulled over to the right of the boundary line  216  in the off-road terrain  210 . It will be appreciated that the emergency vehicle  300  could likewise be pulled over to the left of the boundary line  214  in the off-road terrain (not shown). In any case, the emergency vehicle  300  is stationary. 
     The emergency vehicle  300  can include one or more flashing, oscillating or rotating emergency lights  302  that, when activated, are visible to traffic approaching or driving in front of the emergency vehicle. The emergency vehicle  300  can also include indicia  304  on the top, sides, etc. indicative of the nature of the emergency vehicle, e.g., the words “Towing” or “Police”. Depending on the situation, the emergency vehicle  300  is parked along the roadway  200  adjacent to one or more stationary vehicles  310  and rending aid and/or assistance thereto. The vehicle  310  can be disabled, have a flat tire, have an occupant needing medical assistance, etc. As shown, a single stationary vehicle  310  is located in front of the emergency vehicle  300 . The number and location of such stationary vehicles  310  could be different from that shown. 
     Occupants of the vehicles  300 ,  310  could be entering and exiting the respective vehicle or walking on/around the off-road terrain  210  adjacent to the boundary line  216 . Consequently, it is desirable for traffic in the lane  204  to switch lanes when passing the vehicles  300 ,  310 . In fact, certain states require vehicles driving in lanes adjacent to stopped emergency vehicles to either slow down or switch lanes while passing the vehicles to improve safety. 
       FIGS. 4-6  illustrate one example movement of the host vehicle  20  between lanes  202 ,  204  in response to detecting an emergency vehicle  300  along the roadway  200 . In  FIG. 4 , the controller  76  determines when an emergency vehicle  300  is stopped along the roadway  300  based on images received from the camera assemblies  70   a - 70   h . The camera assemblies  70   a - 70   h  can detect, for instance, the activated lights  302  and/or indicia  304  on the emergency vehicle  300  that distinguish it from other vehicles. The camera assemblies  70   a - 70   h  also detect the presence of any associated stationary vehicle(s)  310  behind or ahead of the emergency vehicle  300 . The controller  76  relies on the proximity sensors  130  and/or camera assemblies  70   a - 70   h  to determine and monitor a distance d 1  between the host vehicle  20  and whichever vehicle  300  or  310  is closest to the host vehicle (the emergency vehicle  300  as shown in  FIG. 4 ). 
     The controller  76  is programmed with a predetermined value for the distance d 1  that, when reached, determines when the host vehicle  20  should switch lanes. The assist system  80  simultaneously determines—via the camera assemblies  70   a - 70   h  and/or proximity sensors  130 —whether other vehicles, objects, obstacles, etc. are present in the lane  202  before the host vehicle  20  switches lanes. If other vehicles prevent the host vehicle  20  from immediately moving laterally when desired, the controller  76  can send signals  114 ,  124  to the respective actuators  110 ,  120  to adjust the vehicle  20  speed until the lane change can be accomplished. The decision whether to adjust the vehicle  20  speed or change lanes  202 ,  204  is based on a series of algorithms and/or look-up tables that rely on the data acquired by the assist system  80 . 
     To this end, the assist system  80  continuously scans the lane  202  and calculates an object-free space S into which the vehicle  20  can move without colliding with other vehicles and/or obstacles. The object-free space S is a 2-dimensional area projected onto the lane  202  whose size and shape is based on the speed and position of any surrounding vehicles or objects (not shown). 
     That said, once the distance d 1  reaches the predetermined value and the object-free space S established, the controller  76  takes active measures to move the host vehicle  20  leftward into the space within the lane  202  while passing the vehicles  300 ,  310 . This occurs without driver intervention or assistance, i.e., the move is autonomously performed. More specifically, the controller  76  actuates the steering gear  68  to rotate the steering wheel  66  counterclockwise from the neutral position, thereby causing the host vehicle  20  to move laterally in the direction L 1  into the object-free space S in the lane  202 . 
     While the lane change occurs, the camera assemblies  70   a - 70   h  capture images of the lane line  206  and the boundary line  214  that are sent to the controller  76 . The controller  76  relies on the proximity sensors  130  to monitor the distance between the host vehicle  20  and each of the lines  206 ,  214 . The wheel position sensor  150  continuously supplies electrical signals  152  to the controller  76 . As a result, the controller  76  can analyze the images from the camera assemblies  70   a - 70   h  and the signals  132  from the proximity sensors  130  and actuate the steering gear  68  in a manner that transitions the host vehicle  20  into the lane  202  while avoiding crossing over the boundary line  214 . The controller  76  ultimately returns the steering wheel  66  to the neutral position such that host vehicle  20  travels in a straight line in the lane  202  in the direction T. The controller  76  sends a signal  162  to the alert  160  to provide feedback to the operator before and/or while the host vehicle  20  is autonomously switched to the lane  202 . At the same time, the controller  76  sends a signal  156  to the turn signal  154  to actuate lights indicative of moving laterally in the direction L 1 . 
     Referring to  FIG. 5 , the host vehicle  20  safely passes both vehicles  300 ,  310  with the lane  204  providing a safe space between the moving host vehicle and the stationary vehicles  300 ,  310 . The controller  76  relies on the camera assemblies  70   a - 70   h  and proximity sensors  130  to continuously monitor the positions of each vehicle  300 ,  310  relative to the host vehicle  20 . The controller  76  then causes the host vehicle  20  to switch back to the lane  204  once the host vehicle is a predetermined minimum distance d 2  past whichever vehicle  300  or  310  is furthest down the roadway  200  in the direction of travel T and the object-free space S determined. 
     In  FIG. 6 , the controller  76  therefore determines when it is safe to move the host vehicle  20  back to the lane  204  and ahead of the vehicle  310  within the predefined, object-free space S. To this end, the host vehicle  20  is laterally moved in the direction L 2  into the lane  204  when the controller  76  determines that the host vehicle  20  reaches the minimum distance d 2  from the vehicle  310 . To move the host vehicle  20  back to the lane  204 , the controller  76  actuates the steering gear  68  to rotate the steering wheel  66  clockwise from the neutral position, thereby causing the host vehicle to move laterally in the direction L 2  into the object-free space S in the lane  204  ahead of the vehicle  310 . The exact trajectory of the lateral movement L 2  and the host vehicle  20  speed are based on maintaining at least the minimum distance d 2  between the host vehicle and the vehicle  310 . 
     While this occurs, the camera assemblies  70   a - 70   h  capture images of the lane line  206  and the boundary line  216  that are sent to the controller  76 . The controller  76  relies on the proximity sensors  130  to monitor the distance between the host vehicle  20  and each of the lines  206 ,  216 . The wheel position sensor  150  continuously supplies electrical signals  152  to the controller  76 . As a result, the controller  76  can analyze the images from the camera assemblies  70   a - 70   h  and the signals  132  from the proximity sensors  130  and actuate the steering gear  68  in a manner that transitions the host vehicle  20  into the lane  204  while avoiding crossing over the boundary line  216 . The controller  76  ultimately returns the steering wheel  66  to the neutral position such that the host vehicle  20  travels in a straight line in the lane  204  in the direction T. The controller  76  sends a signal  162  to the alert  160  to provide feedback to the operator before and/or while the host vehicle  20  is autonomously returned to the lane  204 . At the same time, the controller  76  sends a signal  156  to the turn signal  154  to actuate lights indicative of moving laterally in the direction L 2 . 
     If, upon first detecting the emergency vehicle  300 , the controller  76  determines that vehicles are already present in the lane  202  such that no lane switching can occur, the controller sends a signal  114  to the brake actuator  110  sufficient to slow the host vehicle  20  to a predetermined value, e.g., 40 or 50 mph, that can correspond with state or local law. The controller  76  does not actuate the steering gear  68  and, thus, the host vehicle  20  continues moving in a straight line within the lane  204  in the direction T at the reduced speed. 
     Once the controller  76  determines that the host vehicle  20  reaches the minimum distance d 2  from the vehicle  310 , the controller sends a signal  124  to the throttle actuator  120  to return the host vehicle to the posted legal speed or whatever value below the speed limit is needed due to congestion, weather, etc. The controller  76  sends a signal  162  to the alert  160  to provide feedback to the operator before and/or while the host vehicle  20  is autonomously slowed down or sped up. 
     In another example shown in  FIG. 7-8 , the host vehicle  20  pulls over in response to determining that the emergency vehicle  300  is a police vehicle traveling along the roadway  200 . More specifically, in  FIG. 7 , the host vehicle  20  is traveling in the lane  204  in the direction T. An emergency vehicle  300  approaches the host vehicle  20  from behind and within the lane  204 . The camera assemblies  70   a - 70   h  detect the presence of the emergency vehicle  300  by detecting the activated lights  302  and/or the indicia  304 . The controller  76  analyzes the images and determines that the activated lights  302  and/or indicia  304  are indicative of a police vehicle. 
     The controller  76  also monitors the distance d 3  between the host vehicle  20  and the police vehicle  300 . If the distance d 3  closes to within a predetermined amount, the controller  76  is programmed to autonomously pull the host vehicle  20  over. In other words, the controller  76  assumes such a close distance d 3  indicates the police vehicle  300  wants to pull the host vehicle  20  over and responds accordingly. Furthermore, the camera assemblies  70   a - 70   h  could recognize the police vehicle  300  additionally flashing its headlights (not shown) to indicate a desire for the host vehicle  20  to pull over and respond accordingly. 
     To this end, the controller  76  actuates the steering gear  68  to rotate the steering wheel  66  clockwise from the neutral position, thereby causing the host vehicle  20  to move laterally in the direction L 3 . The host vehicle  20  moves in the direction L 3  until the host vehicle  20  crosses the boundary line  216  and is positioned entirely on the off-road section  210  to the right of the boundary line within the predefined, object-free space S. The controller  76  sends a signal  162  to the alert  160  to provide feedback to the operator before and/or while the host vehicle  20  is autonomously pulled over the boundary line  216 . At the same time, the controller  76  sends a signal  156  to the turn signal  154  to actuate lights indicative of moving laterally in the direction L 3 . 
     At the same time, the controller  76  relies on the proximity sensors  130  to monitor the distance between the host vehicle  20  and the boundary line  216 . The wheel position sensor  150  continuously supplies electrical signals  152  to the controller  76 . As a result, the controller  76  can analyze the images from the camera assemblies  70   a - 70   h  and the signals  132  from the proximity sensors  130  and actuate the steering gear  68  in a manner that transitions the host vehicle  20  to the off-road section  210  right of the boundary line  216 . The controller  76  sends a signal  114  to the brake actuator  110  prior to and/or following the host vehicle  20  crossing the boundary line  216  to apply the brake  112  and ultimately bring the host vehicle  20  to a stop on the off-road section  210 . To this end, the controller  76  can rely on the images from the camera assemblies  70   a - 70   h  to determine when the off-road terrain  210  is present and utilize the brake  112  accordingly. 
     It will be appreciated that although  FIGS. 7-8  illustrate the host vehicle  20  moving from the lane  204  to the off-road terrain  210  to the right of the boundary line  216  the assist system  80  could likewise be used to autonomously move the host vehicle laterally from the lane  202  to the off-road terrain  210  either on the left side of the roadway or the right side in accordance with the present invention. In either instance, the controller  76  will cooperate with the camera assemblies  70   a - 70   h  to ensure that no vehicles are present in the lane  202 ,  204  the host vehicle  20  intends to switch to before actually performing the lane switch. 
     Moreover, the controller  76  can be configured such that the driver cannot override the lateral movement L 3  by the host vehicle  20 . In other words, the host vehicle  20  will automatically pull over to the side of the roadway  200  when a police vehicle  300  moves to within a distance implied to indicate the police want the host vehicle to pull over. That said, the police vehicle  300  moves laterally in the direction L 4 , crosses the boundary line  216 , and parks behind the host vehicle  20 . The police officer can then proceed to normal police procedure for pulled over vehicles. 
     In another example shown in  FIG. 9-11 , the host vehicle  20  switches lanes in response to detecting an emergency vehicle  300  that is an ambulance traveling along the roadway  200 . More specifically, in  FIG. 9 , the host vehicle  20  is traveling in the lane  202  in the direction T. An emergency vehicle  300  approaches the host vehicle  20  from behind and within the lane  202 . The camera assemblies  70   a - 70   h  detect the presence of the emergency vehicle  300  as well as the activated lights  302  and/or indicia  304 . The controller  76  analyzes the images and determines that the activated lights  302  and/or indicia  304  are indicative of an ambulance. 
     The controller  76  also monitors the distance d 4  between the host vehicle  20  and the ambulance  300 . If the distance d 4  closes to within a predetermined amount, the controller  76  is programmed to autonomously laterally move the host vehicle out of the lane  202 . In other words, the controller  76  assumes such a close distance d 4  indicates the ambulance  300  wants the host vehicle  20  out of its traveling path and responds accordingly. 
     To this end, the controller  76  actuates the steering gear  68  to rotate the steering wheel  66  clockwise from the neutral position, thereby causing the host vehicle  20  to move laterally in the direction L 5 . The host vehicle  20  moves in the direction L 5  until the host vehicle  20  crosses the lane line  206  and is positioned entirely within the lane  204  within the predefined, object-free space S. The controller  76  sends a signal  162  to the alert  160  to provide feedback to the operator before and/or while the host vehicle  20  is autonomously moved over the lane line  206 . At the same time, the controller  76  sends a signal  156  to the turn signal  154  to actuate lights indicative of moving laterally in the direction L 5 . 
     During lateral movement in the direction L 5 , the controller  76  relies on the proximity sensors  130  to monitor the distance between the host vehicle  20  and each of the lines  206 ,  216 . The wheel position sensor  150  continuously supplies electrical signals  152  to the controller  76 . As a result, the controller  76  can analyze the images from the camera assemblies  70   a - 70   h  and the signals  132  from the proximity sensors  130  and actuate the steering gear  68  in a manner that transitions the host vehicle  20  into the lane  204  while avoiding crossing over the boundary line  2168 . The controller  76  ultimately returns the steering wheel  66  to the neutral position such that the host vehicle  20  travels in a straight line in the lane  204  in the direction T. 
     Once the host vehicle  20  switches to the lane  204  the ambulance  300  is free to safely pass the host vehicle  20  in the lane  202  as shown in  FIG. 11 . The controller  76  can then decide if the host vehicle remains in the lane  204  or returns to the lane  202  by actuating the steering gear  68  in the manner previously described. 
     The assist system of the present invention is advantageous in that the system can autonomously control the host vehicle on the roadway to respond to the presence and location of emergency vehicles. By relying on the controller and accompanying sensors—instead of solely the driver—to determine where and how close emergency vehicles are to the host vehicle, the present invention can more accurately navigate the host vehicle on the roadway to help increase safety and comply with traffic laws. 
     What have been described above are examples of the present invention. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the present invention, but one of ordinary skill in the art will recognize that many further combinations and permutations of the present invention are possible. Accordingly, the present invention is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims.