Abstract:
A system and method for determining weight on wheels for an aircraft with at least one landing gear; a sensor associated with machinery Light Detection And Ranging scanner; a processor; and memory having instructions stored thereon that, when executed by the processor, cause the system to receive signals indicative of LIDAR image information for a landing gear; evaluate the LIDAR image information against a landing gear model; determine information indicative that the landing gear is locked in response to the evaluating of the LIDAR image information; and determine information indicative that the landing gear is compressed in response to the evaluating of the LIDAR image information against the landing gear model.

Description:
BACKGROUND 
       [0001]    The subject matter disclosed herein relates generally to the field of load detection in rotary-wing aircraft, and more particularly, to a system and method for automatically detecting weight-on-wheels on a landing gear of a rotary-wing aircraft using a remote sensing system. 
       DESCRIPTION OF RELATED ART 
       [0002]    Conventional aircraft may have weight-on-wheel (WOW) sensors and switches to detect if the landing gear strut is compressed and the aircraft is on ground since touch down. Measurement of WOW for fly-by-wire and autonomous rotorcraft can be critical to a correct transition of the rotorcraft control system from airborne state to a ground state and, if not executed properly, can result in dynamic rollover. Current systems with mechanical switches and sensors can be unreliable and do not always actuate at the same amount of force on the landing gear. A system for determining WOW for a rotorcraft using a remote sensing technology that is reliable in the field would be well received in the art. 
       BRIEF SUMMARY 
       [0003]    According to an aspect of the invention, a method for determining weight on wheels for an aircraft includes receiving, with a processor, signals indicative of Light Detection And Ranging (LIDAR) image information for a landing gear; evaluating, with the processor, the LIDAR image information against a landing gear model; determining, with the processor, information indicative that the landing gear is locked in response to the evaluating of the LIDAR image information; and determining, with the processor, information indicative that the landing gear is compressed in response to the evaluating of the LIDAR image information against the landing gear model. 
         [0004]    In addition to one or more of the features described above, or as an alternative, further embodiments could include receiving LIDAR image information while the aircraft is airborne. 
         [0005]    In addition to one or more of the features described above, or as an alternative, further embodiments could include evaluating the LIDAR image information against a landing gear extension model. 
         [0006]    In addition to one or more of the features described above, or as an alternative, further embodiments could include applying weight of the aircraft on the landing gear in response to determining that the landing gear is locked. 
         [0007]    In addition to one or more of the features described above, or as an alternative, further embodiments could include determining a load of the aircraft on the landing gear in response to the determining that the landing gear is compressed. 
         [0008]    In addition to one or more of the features described above, or as an alternative, further embodiments could include transitioning the aircraft to a ground aircraft state in response to determining that the landing gear is compressed. 
         [0009]    In addition to one or more of the features described above, or as an alternative, further embodiments could include receiving the LIDAR image information from a body landing gear and a nose landing gear. 
         [0010]    According to another aspect of the invention, a system for determining weight on wheels for an aircraft with at least one landing gear; a sensor associated with machinery Light Detection And Ranging scanner; a processor; and memory having instructions stored thereon that, when executed by the processor, cause the system to: receive signals indicative of LIDAR image information for a landing gear; evaluate the LIDAR image information against a landing gear model; determine information indicative that the landing gear is locked in response to the evaluating of the LIDAR image information; and determine information indicative that the landing gear is compressed in response to the evaluating of the LIDAR image information against the landing gear model. 
         [0011]    In addition to one or more of the features described above, or as an alternative, further embodiments could include a processor that is configured to receive the LIDAR image data while aircraft is airborne. 
         [0012]    In addition to one or more of the features described above, or as an alternative, further embodiments could include a processor that is configured to evaluate the LIDAR image information against a landing gear extension model. 
         [0013]    In addition to one or more of the features described above, or as an alternative, further embodiments could include a processor that is configured to apply weight of the aircraft on the landing gear in response to determining that the landing gear is locked. 
         [0014]    In addition to one or more of the features described above, or as an alternative, further embodiments could include a processor that is configured to determine a load of the aircraft on the landing gear in response to the determining that the landing gear is compressed. 
         [0015]    In addition to one or more of the features described above, or as an alternative, further embodiments could include a processor that is configured to transition the aircraft to a ground aircraft state in response to determining that the landing gear is compressed. 
         [0016]    In addition to one or more of the features described above, or as an alternative, further embodiments could include a processor that is configured to receive the LIDAR image information from a body landing gear and a nose landing gear. 
         [0017]    Technical function of the invention includes using a remote sensing technology like LIDAR to image an aircraft and its landing gear to provide measurement of compression of a landing gear and wheels so as to indicate accurate weight-on-wheels for a rotary wing aircraft. 
         [0018]    Other aspects, features, and techniques of the invention will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0019]    The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which like elements are numbered alike in the several FIGURES: 
           [0020]      FIG. 1A  is a view of an exemplary aircraft according to an embodiment of the invention; 
           [0021]      FIG. 1B  is a top view of the exemplary aircraft of  FIG. 1A  according to an embodiment of the invention; 
           [0022]      FIG. 1C  is a front view the exemplary aircraft of  FIG. 1A  according to an embodiment of the invention; 
           [0023]      FIG. 2  is a schematic view of an exemplary computing system according to an embodiment of the invention; and 
           [0024]      FIG. 3  is a schematic flow diagram of a WOW algorithm for use with embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]      FIGS. 1A-1C  illustrate general views of an exemplary vehicle in the form of a vertical takeoff and landing (VTOL) rotary-wing aircraft  100  for use with system  200  ( FIG. 2 ) according to an embodiment of the invention. In an embodiment, aircraft  100  can be a fly-by-wire aircraft or an optionally piloted vehicle that autonomously determines aircraft states during flight. As illustrated in  FIG. 1A , aircraft  100  includes a main rotor system  102 , an anti-torque system, for example, a tail rotor system  104 , and a Light Detection and Ranging (LIDAR) perception system  106  positioned laterally on either side of aircraft  100 . Main rotor system  102  is attached to an airframe  108  and includes a rotor hub  110  having a plurality of blades  112  that rotate about rotor hub axis A. Also, the tail rotor system  104  is attached aft of the main rotor system  102  and includes a plurality of blades  114  that rotate about axis B (which is orthogonal to axis A). The main rotor system  102  and the tail rotor system  104  are driven to rotate about their respective axes A, B by one or more turbine engines for providing lift and thrust to aircraft. Although a particular configuration of an aircraft  100  is illustrated and described in the disclosed embodiments, it will be appreciated that other configurations and/or machines include autonomous and semi-autonomous aircraft that may operate in land or water including fixed-wing aircraft and rotary-wing aircraft may also benefit from embodiments disclosed. 
         [0026]    As shown in  FIGS. 1B-1C , LIDAR perception system  106  includes 3D LIDAR scanner modalities  106   a,    106   b  for capturing surface data from, in some non-limiting examples, landing gears and their respective wheels and loads on airframe  108  and for processing by aircraft computer  202 . For example, LIDAR scanner modality  106   a  may capture real-time image data for body landing gear  116  and nose landing gear  120  while LIDAR scanner modality  106   b  may capture real-time image data for body landing gear  118  and nose landing gear  120  in order to determine compression of struts and wheels associated with the landing gears  116 ,  118 , and  120 . The aircraft computer  202  processes, in one non-limiting embodiment, raw LIDAR data acquired through sensors that are, for example, associated with 3D LIDAR scanner modalities  106   a,    106   b  in order to implement the WOW algorithm while airborne. Additional remote sensing modalities such as Laser Detection and Ranging (LADAR) or the like may be provided to enhance the positional awareness of, e.g., an autonomous unmanned aerial vehicle (UAV) as exemplified by vehicle  100 . 
         [0027]      FIG. 2  illustrates a schematic block diagram of a system  200  on board aircraft  100  for implementing the embodiments described herein. As illustrated, aircraft  100  includes the aircraft computer  202  that executes instructions for implementing weight-on-wheels (WOW) algorithm  204  in order to detect weight of aircraft  100  on each landing gear. The aircraft computer  202  receives raw sensor data that is related to one or more aircraft landing gears and wheels that are associated with sensors  206 . In an embodiment, aircraft computer  202  receives Light Detection and Ranging (LIDAR) images from a LIDAR scanner associated with sensor  206 . The computer  202  includes a memory  208  that communicates with a processor  210 . The memory  208  may store the WOW algorithm  204  as executable instructions that are executed by processor  210 . The instructions may be stored or organized in any manner and at any level of abstraction, such as in connection with the execution of the WOW algorithm  204 . Also, in embodiments, memory  208  may include random access memory (RAM), read only memory (ROM), or other electronic, optical, magnetic, or any other computer readable medium onto which is stored the WOW algorithm  204  described below. 
         [0028]    The processor  210  may be any type of processor (such as a CPU or a GPU), including a general purpose processor, a digital signal processor, a microcontroller, an application specific integrated circuit, a field programmable gate array, or the like. In an embodiment, the processor  210  may include an image processor in order to receive images and process the associated image data using one or more processing algorithms to produce one or more processed signals. In an embodiment, the processor  210  may include a LIDAR processor in order to receive LIDAR images and process the associated image data using one or more processing algorithms to produce one or more processed signals. Also, in embodiments, memory  208  may include random access memory (RAM), read only memory (ROM), or other electronic, optical, magnetic, or any other computer readable medium onto which is stored the mixing algorithm described below. 
         [0029]    The system  200  may include a database  212 . The database  212  may be used to store landing gear extension models acquired by LIDAR scanner. Also, sensor data acquired by sensors  206  may be stored in database  212 . The data stored in the database  212  may be based on one or more other algorithms or processes for implementing WOW algorithm  204 . For example, in some embodiments data stored in the database  212  may be a result of the processor  210  having subjected data received from the sensors  206  to one or more filtration processes. The database  212  may be used for any number of reasons. For example, the database  212  may be used to temporarily or permanently store data, to provide a record or log of the data stored therein for subsequent examination or analysis, etc. In some embodiments, the database  212  may store a relationship between data, such as one or more links between data or sets of data acquired on board aircraft  100 . 
         [0030]    The system  100  may provide one or more controls, such as vehicle controls  214 . The vehicle controls  214  may provide directives to aircraft  100  based on, e.g., inputs received from an operator of aircraft  100 . Directives provided to vehicle controls  214  may include actuating one or more actuators of a landing gear or transitioning the aircraft  100  to a ground state from an airborne state. The directives may be presented on one or more input/output (I/O) devices  216 . The I/O devices  216  may include a display device or screen, audio speakers, a graphical user interface (GUI), etc. In some embodiments, the I/O devices  216  may be used to enter or adjust a linking between data or sets of data. It is to be appreciated that the system  200  is illustrative. 
         [0031]      FIG. 3  illustrates an exemplary flow diagram  300  of a process that is performed by aircraft computer  202  for implementing WOW algorithm  204  ( FIG. 2 ) according to an embodiment of the invention. As such,  FIG. 2  is also referenced in the description of the flow diagram  300  in  FIG. 3 . Initially, left LIDAR scanner in block  302  and right LIDAR scanner in block  304  are activated and initialized to determine operability and functionality of the LIDAR scanners in blocks  302  and  304 . In block  306 , LIDAR fault detection is performed where system  200  may run tests on right LIDAR scanner  106   b  to determine its operability for acquiring images of landing gears  118  and  120  ( FIG. 1C ). In block  308 , LIDAR fault detection is performed where system  200  may run tests on left LIDAR scanner  106   a  to determine its operability for acquiring images of landing gears  116  and  120  ( FIG. 1C ). Information from LIDAR fault detection on LIDAR scanners  106   a,    106   b  is communicated to system  200  for evaluation. Fault detection is performed on LIDAR scanners while aircraft  100  is airborne and prior to approaching a landing zone. In an embodiment, system  200  initiates and detects faults within LIDAR system while aircraft  100  is within predetermined or defined operating parameters of the system  200 . For example, system  200  evaluates LIDAR after transmitting a signal to fully extend landing gears  116 - 120  and while aircraft  100  is airborne and approaching a landing zone as determined by altitude, speed, clearance from obstacles on the ground for aircraft  100 . 
         [0032]    In block  310 , left LIDAR scanner  106   a  acquires raw LIDAR image data of body landing gear  116  while aircraft  100  is airborne and approaching a landing zone; in block  312 , left and right LIDAR scanners  106   a,    106   b  acquire raw image data of nose gear  120  ( FIG. 1C ) while aircraft  100  is airborne and approaching a landing zone, and in block  314 , right LIDAR scanner  106   b  acquires raw LIDAR image data of body landing gear  118  while aircraft  100  is airborne and approaching a landing zone. In block  316 , raw image data for body landing gear  116  is transformed into point cloud data and one or more algorithms are applied to the point cloud data to evaluate whether body landing gear  116  is extended (i.e., whether the gear is locked). In an embodiment, the 3D point cloud data is evaluated against a 3D model of a fully extended body landing gear  116  previously imaged through LIDAR scanner  106   a  to determine whether the image data conforms to the 3D model of a fully extended landing gear. Also, in block  318 , raw image data of a nose landing gear  120  is transformed into point cloud data and evaluated by applying one or more algorithms to determine whether nose landing gear  120  is fully extended. In an embodiment, the 3D point cloud data is evaluated against a 3D model of a fully extended nose landing gear  120  previously imaged through LIDAR scanners  106   a,    106   b  to determine whether the image data conforms to the 3D model of a fully extended landing gear. Similarly, in block  320 , raw image data for right landing gear  118  is transformed into point cloud data and one or more algorithms are applied to the point cloud data to evaluate whether right landing gear  118  is fully extended. In an embodiment, the 3D point cloud data is evaluated against a 3D model of a fully extended body landing gear  118  previously imaged through LIDAR scanner  106   b  to determine whether the image data conforms to the 3D model of a fully extended landing gear. If system  200  determines that landing gears  116 - 120  are fully extended, the system  200  can autonomously descend onto the landing zone site until all landing gears are in contact with the ground and weight of the helicopter at least partially compresses the struts and wheels of the respective landing gears  116 - 120 . 
         [0033]    In block  322 , the 3D point cloud data is evaluated against a 3D model of a deformed body landing gear  116  and its associated wheel previously imaged through LIDAR scanner  106   a  in order to determine whether the image data conforms to the 3D model. The processed 3D image will conform to the 3D model if the strut and wheel is deformed under minimum load conditions to indicate that the aircraft landing gear is contacting the ground. In an embodiment, image data of an airframe can be obtained through LIDAR scanner  106   a  and evaluated against a 3D model of the body landing gear  116  to determine side loads on aircraft  100 . Also, in block  324  the 3D point cloud data is evaluated against a 3D model of a deformed nose landing gear  120  and its associated wheel previously imaged through LIDAR scanners  106   a,    106   b  in order to determine whether the image data conforms to the 3D model. The processed 3D image will conform to the 3D model if the strut and wheel is deformed under minimum load conditions to indicate that the aircraft landing gear is contacting the ground. 
         [0034]    Similarly, in block  326 , the 3D point cloud data is evaluated against a 3D model of a deformed right landing gear  118  and its associated wheel previously imaged through LIDAR scanner  106   b  in order to determine whether the image data conforms to the 3D model. The processed 3D image will conform to the 3D model if the strut and wheel is deformed under minimum load conditions to indicate that the aircraft landing gear is contacting the ground. In an embodiment, image data of an airframe can be obtained through 
         [0035]    LIDAR scanner  106   b  and evaluated against a 3D model of the body landing gear  118  to determine side loads on aircraft  100 . Upon determining that aircraft  100  is applying weight (or load) on each of the three landing gears  116 - 120  as determined through compression of landing gears  116 - 120  and their respective wheels, system  200  can transition the rotorcraft control system from airborne state to a ground state, either autonomously or through pilot control. 
         [0036]    Benefits and technical effects of the invention include using a remote sensing technology like LIDAR to image an aircraft and its landing gears in order to provide measurement of compression of a landing gear and wheels so as to indicate accurate weight-on-wheels for a rotary wing aircraft. Additional benefits and technical effects can include fault detection of the state of one or more landing gears to determine whether the landing gear is extended. 
         [0037]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. While the description of the present invention has been presented for purposes of illustration and description, it is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications, variations, alterations, substitutions or equivalent arrangement not hereto described will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. Additionally, while the various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.