Abstract:
Systems and methods for providing improved situational awareness for an aircraft while taxiing. An exemplary method generates reflectivity data based on an associated emission at a transceiver located on an aircraft. At a processor, targets are determined if a portion of the generated reflectivity data is greater than a predefined threshold. Then, the analyzed targets are determined as to whether they are within a dynamically defined three-dimensional envelope. The envelope is based on wingtip light module speed and trajectory. On a display device, an indication of the nearest target is presented at the associated range to the nearest target.

Description:
PRIORITY CLAIM 
       [0001]    This application claims the benefit of U.S. Provisional Applications Ser. Nos. 61/653,297, filed May 30, 2012, and 61/706,632, filed Sep. 27, 2012, the contents of which are hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The Flight Safety Foundation (FSF) estimates the apron-damage costs to the world&#39;s airlines to be $4 billion every year. For corporate fleets, the damage-related cost was estimated to be $1 billion annually. 
         [0003]    The presented apron-damage costs include direct costs resulting from material and work related to an accident, and indirect costs resulting from aircraft being not in operation, harming the public image of airlines, incident investigations, etc. 
         [0004]    Three main causes of surface accidents were indentified from the NTSB database: the failure to maintain adequate visual lookout, the failure to perceive distance between the wings and obstacles, and the failure to maintain required clearance. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention provides systems and methods for providing improved situational awareness for an aircraft while taxiing. An exemplary method generates reflectivity data based on an associated emission at a transceiver located at one or more wingtip light modules of an aircraft. The transceiver may be located in dedicated areas of the wingtip or other parts of the aircraft (e.g., engine, fuselage). At a processor, targets are determined if a portion of the generated reflectivity data is greater than a predefined threshold based on an algorithm used for calculation of the reflectivity and associated certainty. Then, the analyzed targets are determined as to whether they are within a dynamically defined three-dimensional envelope. The envelope is based on wingtip light module speed and trajectory. On a display device, an indication of the nearest target is presented at the associated range to the nearest target. 
         [0006]    In one aspect of the invention, a first range overhead display is generated if the closest target is farther than a threshold distance from the aircraft. The first range overhead display includes an aircraft icon and one or more target cones beginning at the respective wingtip of the aircraft icon. A second range overhead display is generated if the closest target is farther than the threshold distance from the aircraft. The second range overhead display includes an aircraft icon and one or more target cones beginning at the respective wingtip of the aircraft icon. 
         [0007]    In another aspect of the invention, the target cones of the first range overhead display have a greater range than the target cones of the second range overhead display. 
         [0008]    In still another aspect of the invention, the target cones include range line(s) located previously designated distances from at least one of the aircraft or the associated wingtip. 
         [0009]    In yet another aspect of the invention, the indication of the nearest target includes a highlighted range line of the cones that is associated with the nearest target reflectivity data or a distance value associated with the nearest target reflectivity data. 
         [0010]    In still yet another aspect of the invention, the indication of the nearest target includes at least a partial outline of an airport structure associated with the nearest target reflectivity data. The outline of the airport structure is based on previously stored airport information. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Preferred and alternative embodiments of the present invention are described in detail below, with reference to the following drawings: 
           [0012]      FIGS. 1 and 2  are diagrams of an exemplary system formed in accordance with an embodiment of the present invention; 
           [0013]      FIG. 3  is a top view of an aircraft implementing the system shown in  FIGS. 1 and 2 ; 
           [0014]      FIGS. 4-1  and  4 - 2  are flow diagrams illustrating an exemplary process performed by the system shown in  FIGS. 1 and 2 ; and 
           [0015]      FIGS. 5-1  and  5 - 2  are wingtip sensor images at two different ranges. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    In one embodiment, as shown in  FIGS. 1-3 , an exemplary airport surface collision-avoidance system (ASCAS)  18  includes light module system(s)  30 ,  32  and a cockpit system  44 . Each light module system(s)  30 ,  32  includes a transceiver (e.g., emitter/sensor (e.g., radar))  26 , one or more navigation/position lights  34 , a processor  36 , and a communication device  38 . The transceiver  26  is in (wired or wireless) communication via the communication device  38  to the cockpit system  44 . 
         [0017]    In one embodiment, the cockpit system  44  includes a processor  50  (optional), a communication device (wired and/or wireless)  52 , a display  54 , a user interface (UI) device  56 , memory  58 , and a position device  60 . The cockpit system  44  provides audio and/or visual cues (e.g., via headphones, display) based on sensor-derived and processed information. 
         [0018]    Based on information from the sensors  26 , the cockpit system  44  provides some or all of the following functions: detect and track intruders, evaluate and prioritize threats, and declare and determine actions. Once an alert associated with a detection has been produced, then execution of a collision-avoidance action (e.g., stop the aircraft, maneuver around intruder, etc.) is manually performed by the vehicle&#39;s operator, or automatically by an automation system (e.g., autobrakes). 
         [0019]    In one embodiment, some or all of the processing of the sensor information is done by the processor  36  at the sensor level and/or the processor  50  at the cockpit system  44 . 
         [0020]    In one embodiment, situational awareness is improved by integration with an automatic dependent surveillance-broadcast/traffic information service-broadcast (ADS-B/TIS-B), airport/airline information on vehicles/aircraft/obstacles (e.g., through WiMax), and with synthetic vision system/electronic vision system/combined vision system (SVS/EVS/CVS) received by the respective devices using the communication devices  38 ,  52 . 
         [0021]    In one embodiment, the present invention reduces false alarms by exploiting flight plan and taxi clearance information and airport building/obstacle databases stored in the memory  58  or received from a source via the communication devices  38 ,  52 . 
         [0022]    The sensors  26  are included in the wing and tail navigation light module systems  30 ,  32  or are placed at other locations about the aircraft. The sensors  26  provide near-complete sensor coverage of the aircraft  20 . Full coverage can be attained by placing sensors in other lights that are strategically located on the aircraft  20 . 
         [0023]    The pilot is alerted aurally, visually, and/or tactilely. For example, a visual alert presented on a display (e.g., an electronic flight bag (EFB) display) shows at least partial aircraft outline and/or highlights of any obstructions. Aural alerting can for instance be through existing installed equipment, such as the interphone or other warning electronics or possibly the enhanced ground proximity warning system (EGPWS) platform. 
         [0024]      FIGS. 4-1  and  4 - 2  show an exemplary process  80  performed by the cockpit system  44  and/or the light module system(s)  30 ,  32 . First, at a block  82 , the transceivers  26  generate data based on reflections received at their sensors based on signals sent by their emitters. Next, at a block  84 , the processor  50  filters the sensor data based on predefined values/parameters and/or dynamically defined values/parameters. Then, at a block  86 , the processor  50  outputs target information based on the filtered sensor data. The steps not included are the transmission of information between the light module systems  30 ,  32  and the cockpit system  44 . 
         [0025]      FIG. 4-2  shows details of the step performed at block  84 . First, at a block  94 , the processor  50  dynamically determines dimensions of a sensor&#39;s three-dimensional envelope for each light module system (sensor) based on the speed of the light module system (i.e., wingtip speed) calculated from aircraft speed information, light module system trajectory information, and predefined vertical boundary information. The speed and trajectory information are derived from aircraft speed and trajectory information received from the position device  60 . 
         [0026]    At a decision block  96 , the processor  50  determines whether the sensor (reflectivity) data that are within the sensor&#39;s three-dimensional envelope have a certainty value greater than a predefined threshold. If the certainty value is not greater than the predefined threshold, then those sensor data are not identified as a target/obstacle (i.e., filtered out), see block  98 , otherwise the sensor data are identified as a target/obstacle (block  100 ). 
         [0027]    After blocks  96 ,  98 , the processor  50  determines whether a display setting is set at manual or automatic (decision block  102 ). If the display setting is manual, then, at a block  104 , the processor  50  generates and sends targets/obstacles to the display  54  according to the identification at block  100  and a range setting set by a user of the UI device  56 . If the display setting is automatic, then, at a block  108 , the processor  50  outputs targets/obstacles from the set of identified targets/obstacles to the display at a first range value, if the closest target/obstacle is within a threshold distance. If the closest target/obstacle is not within the threshold distance, the processor  50  outputs the filtered target/obstacle at a second range value. 
         [0028]    In one embodiment, the thresholds for sensor FOV of interest are assessed, based on maximum and minimum stopping distances. 
         [0029]    Maximum distance:
       The braking action is executed by aircraft.   Aircraft is moving by the ground speed of 16 m/s, which corresponds to the maximum assumed taxi speed.   Aircraft is moving on wet-poor runway with airplane braking coefficient μ B =0.3.   Aircraft is producing zero lift.   No skid is assumed.       
 
         [0035]    Minimum distance:
       The braking action is executed by aircraft.   Aircraft is moving by the ground speed of 1.4 m/s, which corresponds to the speed of the aircraft being pushed backward (fast human walk).   Aircraft is moving on wet-poor runway with airplane braking coefficient μ B =0.3.   Aircraft is producing zero lift.   No skid is assumed.       
 
         [0041]    The following is an exemplary calculation of the braking distance. One may implement this calculation differently. Aircraft braking coefficient (μ B ) includes a coefficient summarizing the retarding forces acting on a wheel under braking In one embodiment, μ B =F braking /(mg−L). Definitions are: F braking —braking force, m—aircraft mass, L—lift, g—gravitational acceleration. The aircraft braking coefficient is not equivalent to the tire-to-ground friction coefficient. The estimated airplane braking coefficient is an all-inclusive term that incorporates effects due to the runway surface, contaminants, and airplane braking system (e.g., antiskid efficiency, brake wear). 
         [0042]    The resulting time for executing corrective action is derived from the relationship between work and object energy. The work is defined as: 
         [0000]                  (1)
 
         [0000]      where 
         [0000]                  (2)
 
         [0043]    For zero lift (the lift produced by the aircraft during slow motions can be ignored) is stated: 
         [0000]                  (3)
 
         [0044]    Braking distance derived from the relation between work and energy is: 
         [0000]                  (4)
 
         [0045]    By substitution, distance of uniformly decelerated motion is: 
         [0000]                  (5)
 
         [0046]    The formula for resulting time needed to decelerate the aircraft at given braking force is derived as: 
         [0000]                  (6)
 
         [0047]    Equation 6 is used to define the time needed to stop the aircraft during the highspeed taxi in the vicinity of the runway, as well as for determination of time to stop while the aircraft is being pushed back out of the gate. 
         [0048]      FIG. 5-1  shows a screen shot of an exemplary image  120 - 1  of a wingtip sensor display at a normal range setting. The image  120 - 1  is presented on the cockpit display  54 , such as that included on the instrument panel or included in a stand-alone device (e.g., electronic flight bag (EFB)). 
         [0049]    The image  120 - 1  includes an aircraft icon  124  located at a bottom center. Sensor cones  130 ,  132  emanate from the wingtips (i.e., sensors) of the aircraft icon  124 . A distance scale is identified on the cones  130 ,  132 . In this example, the scale includes meter measurements of 50, 70, 90, 100, and 110 measured from either the aircraft&#39;s nose or wingtip. In this example, the closest target/obstacle has been identified at 85 m, as identified by the 85 m line  140  being highlighted within the cones  130 ,  132 . 
         [0050]    In one embodiment, the 85 m line  140  is highlighted when the sensors in both wingtips identify the nearest target/obstacle at 85 m or only one of the wingtip sensors sees the nearest target/obstacle at 85 m. 
         [0051]      FIG. 5-2  shows a screen shot of an exemplary image  120 - 2  that is similar to the image  120 - 1 , except that it presents a closer range than does the image  120 - 1 . The aircraft icon  124  appears larger and the cones  130 ,  132  extend out to only about 70 m. The image  120 - 2  is presented when the user selects the close-range (precision) display mode or the system  18  has determined that there is a target/obstacle located within a threshold distance (e.g., 70 m) from the aircraft. The system  18  has detected a target/obstacle at 26 m based on information from the port wingtip sensor. The image  120 - 2  shows the detected target/obstacle by either highlighting the 26 m distance line, displaying a 26 m call-out balloon, and/or displaying at least a partial outline image  136  of the detected target/obstacle. For example, the system  18  detects an airport building. Based on airport facility information stored in the memory  58 , the outline image  136  is provided to accurately present an outline of the associated building based on the range setting of the image  120 - 2 . 
         [0052]    In one embodiment, one power source is shared for both the radars (forward and aft) and the wireless module. In one embodiment, the common wireless module is placed in the forward position light and is used for transmitting data between the wing and the cockpit UI device or the tug tractor driver/wing-walker UI device. 
         [0053]    Wingtip velocity in a taxi turn may reach 8 meters per second (27 fps) and, in one embodiment, the minimum time for alerting and action by the pilot is set at eight seconds. In one embodiment, the system derives a taxi ground speed related to the wingtip, in order to advance the detection time. 
         [0054]    While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow.