Patent Publication Number: US-2023135561-A1

Title: Airport Tugs, Systems, and Methods of Operation Thereof

Description:
RELATED APPLICATIONS 
     The present application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Pat. Application No. 63/274,220, filed on Nov. 1, 2021, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND INFORMATION 
     Airport tugs are ground vehicles used to push or pull an airplane on a tarmac. Conventional tugs are operated by a human driver, are powered by an internal combustion engine, and are typically used to move an airplane away from an airport terminal. After the aircraft has been pushed away from the terminal, the aircraft uses its jet engines to taxi to a runway for takeoff. However, these conventional tugs must be driven by an onboard human driver, produce undesirable emissions and noise, and are only meant to move the aircraft relatively short distances. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate various embodiments and are a part of the specification. The illustrated embodiments are merely examples and do not limit the scope of the disclosure. Throughout the drawings, identical or similar reference numbers designate identical or similar elements. 
         FIG.  1    illustrates an exemplary airport tug management system according to principles described herein. 
         FIGS.  2 - 3    illustrate exemplary implementations of the airport tug management system of  FIG.  1    according to principles described herein. 
         FIGS.  4 - 5    illustrate exemplary flow diagrams depicting various operations that may be performed according to principles described herein. 
         FIG.  6    illustrates an exemplary view of an airport facility according to principles described herein. 
         FIGS.  7 - 8    illustrate additional exemplary flow diagrams depicting various operations that may be performed according to principles described herein. 
         FIG.  9    illustrates an exemplary method of operation of an airport tug according to principles described herein. 
         FIG.  10    illustrates an exemplary computing device according to principles described herein. 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS 
     Airport tugs, systems, and methods of operation thereof are described herein. In certain examples, an airport tug such as described herein may be configured to navigate an airport facility autonomously. In certain examples, for instance, an exemplary airport tug may comprise a coupling portion configured to engage with a receiving portion of an aircraft, one or more sensors configured to collect sensor data descriptive of environmental conditions in a vicinity of the airport tug, a memory storing instructions, and one or more processors communicatively coupled to the memory and configured to execute the instructions to perform a process. The process may comprise monitoring, based on the sensor data, the environmental conditions in the vicinity of the airport tug and directing, based on the monitoring of the environmental conditions and while the coupling portion is engaged to the receiving portion, autonomous movement of the airport tug to transport the aircraft from a starting position to a designated delivery position for the aircraft at the airport facility. 
     A form factor of airport tugs such as those described herein may be similar to the form factor of conventional airport tugs used at airports. However, airport tugs such as those described herein may differ from conventional airport tugs in one or more ways. For example, as will be described further herein, airport tugs such as those described herein may be electrically powered, may have one or more sensors or sensor arrays for collecting sensor data about environmental conditions, may be configured to autonomously navigate an airport environment, and/or may be configured to optionally switch to remote control operation in certain situations to navigate the airport environment as directed by a remote operator (e.g., that is located within a cockpit of an aircraft, within a control tower, on the tarmac, or any other suitable location). Other differences between the airport tugs described herein and conventional airport tugs will be evident from the description that follows. 
     Various advantages and benefits are associated with the airport tugs, systems, and methods described herein. Such benefits may be provided to airlines, airports, airport workers, travelers, those who live near airports, and to the public generally. For example, airliner emissions may be significantly reduced, on the order of 10% or more per flight in some implementations, by eliminating the need to use the aircraft’s jet engines during pre-take-off operations and/or post-landing operations, especially taxiing. In addition, in examples where airport tugs such as those described herein operate by way of electric power, the airport tugs may leverage the use of renewable energy to power the moving of aircraft around airport tarmacs. Electricity is also significantly less expensive than jet fuel, thus reducing costs. Jet engines are also noted for the high levels of noise they produce, and so by reducing the amount of time the engines are running, noise at and around airport facilities may be meaningfully reduced. These and other benefits that may be provided by the airport tugs, systems, and methods described herein will be evident from the disclosure that follows. 
       FIG.  1    illustrates an exemplary airport tug management system  100  (“system  100 ”) that may be implemented according to principles described herein. As shown, system  100  may include, without limitation, a memory  102  and a processor  104  selectively and communicatively coupled to one another. Memory  102  and processor  104  may each include or be implemented by hardware and/or software components (e.g., processors, memories, communication interfaces, instructions stored in memory for execution by the processors, etc.). In some examples, memory  102  and/or processor  104  may be implemented by any suitable computing device. In other examples, memory  102   and/or processor  104  may be distributed between multiple devices and/or multiple locations as may serve a particular implementation. Illustrative implementations of system  100  are described herein. 
     Memory  102  may maintain (e.g., store) executable data used by processor  104  to perform any of the operations described herein. For example, memory  102  may store instructions  106  that may be executed by processor  104  to perform any of the operations described herein. Instructions  106  may be implemented by any suitable application, software, code, and/or other executable data instance. 
     Memory  102  may also maintain any data received, generated, managed, used, and/or transmitted by processor  104 . Memory  102  may store any other suitable data as may serve a particular implementation. For example, memory  102  may store data associated with airport facilities (e.g., terminal/runway maps), aircraft information, sensor data, airport navigation rulesets/algorithms, air traffic control information (e.g., vector information of entities (e.g., aircraft, airport personnel, airport tugs, transport vehicles, etc.) at or within a vicinity of an airport facility), and/or any other suitable data. 
     Processor  104  may be configured to perform (e.g., execute instructions  106  stored in memory  102  to perform) various processing operations associated with an airport tug autonomously navigating an airport facility. For example, processor  104  may perform one or more operations described herein to monitor environmental conditions within a vicinity of an airport tug and autonomously or automatically adjust movement of the airport tug based on the environmental conditions. As used herein, the expressions “autonomously” or “automatically” mean that an operation (e.g., an operation of autonomously transporting an aircraft) or series of operations are performed without requiring further input from a user. For example, system  100  may autonomously plot a route for an airport tug to follow at an airport facility and direct the airport tug to autonomously navigate along the route without requiring input from a user. These and other operations that may be performed by processor  104  are described herein. 
     System  100  may be implemented in any suitable manner.  FIG.  2    shows an exemplary implementation  200  in which system  100  may be provided in certain examples. As shown in  FIG.  2   , implementation  200  includes an airport tug  202  that is configured to engage with an aircraft  204  to facilitate transport of an aircraft  204  at an airport facility  206 . System  100  may be implemented entirely by airport tug  202 . Alternatively, system  100  may be distributed across airport tug  202  and aircraft  204 , or distributed across airport tug  202 , aircraft  204 , and/or any other suitable computer system/device. 
     Aircraft  204  may correspond to any suitable type of aircraft that may be transported by airport tug  202 . For example, aircraft  204  may correspond to any type of airplane (e.g., a commercial jet, a private jet, a military jet, etc.), helicopter, drone, or vertical take-off and landing (VTOL) aircraft. 
     As shown in  FIG.  2   , airport tug  202  includes, but is not limited to, a memory  208  that stores instructions  210 , a processor  212 , a communication interface  214 , a plurality of sensors  216  (e.g., sensors  216 - 1  through  216 -N) and a coupling portion  218 . 
     Memory  208  may maintain (e.g., store) executable data used by processor  212  to perform any of the operations described herein. For example, memory  208  may store instructions  210  that may be executed by processor  212  to perform any of the operations described herein. Instructions  210  may be implemented by any suitable application, software, code, and/or other executable data instance. 
     Memory  208  may also maintain any data received, generated, managed, used, and/or transmitted by processor  212 . Memory  208  may store any other suitable data as may serve a particular implementation. For example, memory  208  may store data similar to that stored by memory  102  described above. 
     Processor  212  may be configured to perform (e.g., execute instructions  210  stored in memory  208  to perform) various processing operations associated with airport tug  202  autonomously navigating airport facility  206 . For example, processor  212  may perform one or more operations described herein to autonomously engage with and/or transport aircraft  204  at airport facility  206 . These and other operations that may be performed by processor  104  are described herein. 
     Communication interface  214  may implement any suitable wireless or wired communication technology to communicate with other airport tugs, aircraft  204 , an air traffic control system, and/or any other suitable entity at airport facility  206 . For example, by way of communication interface  214 , airport tug  202  may receive information from an air traffic control system regarding transport instructions and/or traffic conditions at airport facility including, for example, vectors of other airport tugs, vectors of other airport vehicles, vectors of aircraft, etc. at airport facility  206 . In certain examples, communication interface  214  may be configured to wirelessly communicate with a remote control device operated by a remote operator and configured to remotely control airport tug in instances such as described herein where airport tug  202  is not operating autonomously. 
     Sensors  216  may be configured to collect sensor data descriptive of environmental conditions in a vicinity of airport tug  202 . Sensors  216  may include any suitable number and/or type of sensor that may be used to facilitate navigation of airport tug  202  at airport facility  206 . For example, sensors  216  may include, but are not limited to, light detection and ranging (LiDAR) sensors (e.g., rotating and/or solid state LiDAR sensors), ultrasonic sensors, radar sensors (e.g., using short range radar and/or long range radar), cameras (e.g., mono and/or stereo cameras), GPS sensors, and/or any other suitable type of sensor. Sensors  216  may be configured in any suitable manner to facilitate airport tug  202  identifying and using landmarks and features common to airport facility  206 , such as the edges of runways or pavement, tarmac markers, lights, posts, etc. to facilitate airport tug  202  autonomously navigating airport facility  206 . 
     Coupling portion  218  may include any suitable mechanism that may be configured to engage with aircraft  204  to facilitate airport tug  202  pushing or pulling aircraft  204  at airport facility  206 . To that end, aircraft  204  includes a receiving portion  220  that is configured to engage in any suitable manner with coupling portion  218  of airport tug  202 . For example, in certain implementations, receiving portion  220  may correspond to the front landing gear of aircraft  204 . In such an example, coupling portion  218  may be configured to attach in any suitable manner to the front landing gear to push/pull aircraft  204  at airport facility  206 . 
     Airport tug  202  may have any suitable form factor and may include any suitable additional or alternative components as may serve a particular implementation. For example, airport tug  202  may include a plurality of wheels (e.g., four wheels) and may include one or more actuators configured to control movement functions (e.g., braking, acceleration, steering, etc.) of airport tug  202 . In certain implementations, airport tug  202  may be electrically powered. In such examples, airport tug  202  may have one or more electric motors and batteries configured to provide power to the electric motors. In addition, airport tug  202  may include a computer screen for manual interfacing and charging interface equipment (such as a plug-in charging port and/or inductive charging equipment). In some implementations, airport tug  202  may include manual control interfaces (e.g., a steering wheel, a brake pedal, an acceleration petal, etc.) to facilitate a human rider controlling airport tug  202  in instances where airport tug  202  is not operating autonomously or by way of a remote control device. 
     In some implementations, airport tug  202  may be configured to provide auxiliary electric power to other devices and/or vehicles that may need power at airport facility  304 . For example, airport tug  202  may be configured to provide auxiliary power to aircraft  204  on the tarmac via an umbilical that extends from airport tug  202  to aircraft  204 . Additionally or alternatively, airport tug  202  may be configured to provide auxiliary power to maintenance crews, emergency response crews, baggage vehicles, and/or any other suitable entity. 
     Airport tug  202  may be configured for autonomous navigation in a relatively controlled and/or predictable environment such as airport facility  206 . Airport facility  206  may correspond to any suitable location where it may be desirable to transport aircraft  204  by way of airport tug  202 . For example, airport facility  206  may correspond to a commercial service airport, a regional airport, a cargo service airport, a military service airport, a VTOL aircraft facility (e.g., that is specifically configured for manned VTOL drones/aircraft), or any other suitable type of airport facility. 
     To facilitate autonomous operation of airport tug  202 , system  100  (e.g., processor  104  or processor  212  of airport tug  202 ) may be configured to monitor, based on sensor data collected by sensors  216 , environmental conditions in a vicinity of airport tug  202 . As used herein, “environmental conditions” may refer to any condition in a vicinity of airport tug  202  that may facilitate or otherwise affect autonomous navigation of airport tug  202  at the airport facility. For example, environmental conditions may refer to tarmac conditions, a proximity of airport tug to one or more other objects (e.g., other airport tugs, other aircraft, vehicles, airport personnel, etc.), markers on tarmac, lights, weather conditions, and/or any other suitable condition. 
     Based on the environmental conditions, system  100  may direct autonomous movement of airport tug  202  at the airport facility in any suitable manner. For example, while coupling portion  218  of airport tug  202  is engaged with receiving portion  220  of aircraft  204 , system  100  may direct autonomous movement of airport tug  202  to transport aircraft  204  from a starting position to a designated delivery position for aircraft  204  at the airport facility. 
     The starting position may correspond to any suitable position at airport facility  206  where it may be desirable to have coupling portion  218  of airport tug  202  engage with receiving portion  220  of aircraft  204 . For example, the starting position may correspond to a docked position of aircraft  204  at a gate of airport facility  206 . In such examples, the starting position may be a location where aircraft  204  connects to a jetway at a terminal of airport facility  206 . In certain alternative examples, the starting position may correspond to an end of a runway after aircraft  204  lands at airport facility  206 . 
     The designated delivery position may correspond to any suitable position at airport facility  206  where it may be desirable to deliver aircraft  204 . For example, the designated delivery position may correspond to a designated departure position on a runway where aircraft  204  is cleared to begin accelerating for takeoff. In certain alternative examples, the designated delivery position may correspond to a specific terminal or gate at airport facility  206  where passengers disembark, a maintenance area at airport facility  304 , or any other suitable position. In such examples, airport tug  202  may push or pull aircraft  204  to the designated delivery position instead of the jet engines of aircraft  204  being used to taxi aircraft  204 , thereby reducing fuel consumption and noise at airport facility  206 . 
     System  100  may direct the autonomous movement of airport tug  202  in any suitable manner. For example, the monitoring of the environmental conditions may include detecting a change in the environmental conditions during the autonomous movement of airport tug  202 . Based on the change in the environmental conditions, the directing of the autonomous movement of airport tug  202  may further comprise autonomously adjusting a movement of airport tug. The change may correspond to any suitable change that may occur in an airport environment at an airport facility. For example, the change in the environmental conditions may be due to the sensor data indicating that another airport tug is crossing paths or is about to cross paths in front of airport tug  202 . In such examples, airport tug  202  may adjust the movement by stopping, adjusting velocity, plotting an alternate path, and/or performing any other suitable adjustment to the movement. 
     The sensor data and/or environmental conditions may be used in any suitable manner to facilitate autonomous navigation of airport tug  202 . For example, system  100  may use the sensor data to provide instructions to actuators (e.g., which control acceleration, braking, steering, etc.) of airport tug  202  and/or to plot a path for airport tug  202  to take from the starting position to the designated delivery position. System  100  may implement any suitable process or technology to facilitate the autonomous movement of airport tug  202 . For example, an exemplary process may include system  100  implementing airport specific hard coded rules (e.g., boundary restrictions, speed restrictions, distance between aircraft restrictions, etc.), obstacle avoidance algorithms, predictive modeling, machine learning algorithms, artificial intelligence operations, and/or object recognition algorithms to facilitate airport tug  202  autonomously navigating airport facility  206 . 
     In certain examples, the autonomous movement of airport tug  202  may additionally or alternatively comprise airport tug  202  autonomously navigating toward aircraft  204  and autonomously engaging coupling portion  218  with receiving portion  220 . 
     In certain examples, the autonomous movement of airport tug  202  may additionally or alternatively comprise airport tug  202  autonomously disengaging, after airport tug  202  and aircraft  204  arrive at the designated delivery position, coupling portion  218  of airport tug  202  from receiving portion  220  of aircraft  204 . 
     In addition to sensor data, system  100  may use information received from an air traffic control system in any suitable manner to facilitate airport tug  202  autonomously navigating airport facility  206 . Such information may include any suitable information regarding vectors (e.g., positions, velocities, headings, etc.) of objects or personnel at an airport facility that is monitored or controlled by the air traffic control system. For example, the information may include airport tug position information, aircraft position information, airport personnel position information, and/or any other suitable information. In certain examples, the information may include transport instructions or requests for an airport tug to autonomously travel to a particular location at airport facility  206  or to engage with and deliver a particular aircraft to a designated position at airport facility  206 . 
       FIG.  3    shows an exemplary configuration  300  in which system  100  may be implemented in conjunction with an air traffic control system  302 . As shown in  FIG.  3   , configuration  300  includes an airport facility  304  where a plurality of airport tugs  202  (e.g., airport tugs  202 - 1  through  202 -N) and a plurality of aircraft  204  (e.g., aircraft  204 - 1  through  204 -N) are located. Airport facility  304  may correspond to any suitable type of airport facility such as described herein. System  100  may be implemented entirely by one of airport tugs  202 . Alternatively, system  100  may be distributed across airport tugs  202 , aircraft  204 , and air traffic control system  302  or distributed across airport tugs  202 , aircraft  204 , air traffic control system  302 , and/or any other suitable computer system/device. 
     As shown in  FIG.  3   , airport tugs  202 , aircraft  204 , and air traffic control system  302  are configured to communicate with each other and with an airport traffic control system  302  by way of a network  306 . Network  306  may include, but is not limited to, one or more wireless networks (Wi-Fi networks), wireless communication networks, mobile telephone networks (e.g., cellular telephone networks, 5G networks, etc.), mobile phone data networks, broadband networks, narrowband networks, the Internet, local area networks, wide area networks, and any other networks capable of carrying data and/or communications signals between airport tugs  202 , aircraft  204 , and airport traffic control system  302 . Communications between airport tugs  202 , aircraft  204 , airport traffic control system  302 , and any other device or system may be transported using any one of the above-listed networks, or any combination or sub-combination of the above-listed networks. 
     In certain examples, airport tugs  202  may be configured to communicate with each other (e.g., either directly or by way of network  306 ) to share information regarding environmental conditions at airport facility  304  and/or facilitate autonomous navigation at airport facility  304 . For example, airport tug  202 - 1  may be configured to communicate in any suitable manner with airport tug  202 - 2  to share information regarding traffic conditions, weather conditions, tarmac conditions, etc. at airport facility  304 . 
     Airport traffic control system  302  may be implemented in any suitable manner. For example, airport traffic control system  302  may be implemented by one or more computing devices such as a central server located at a control tower of airport facility  304  or any other suitable location. Air traffic control system  302  may provide airport tugs  202  with information about the environment, such as an up-to-date map of the airport tarmac environment. Air traffic control system  302  may be configured to alert airport tugs  202  to possible congestion, potentially even optimizing airport tug routes to avoid tarmac “traffic jams,” provide information regarding weather conditions, vectors of airport tugs  202 , vectors of aircraft  204 , vectors of airport personnel, vectors of other vehicles at airport facility  304 , and/or any other suitable information. Airport traffic control system  302  may transmit such information in any suitable manner by way of network  306  to airport tugs  202  to facilitate airport tugs  202  autonomously navigating airport facility  304 . For example, airport traffic control system  302  may continually stream such information to airport tugs  202  so that they have up-to-date information regarding conditions at airport facility  304 . Alternatively, airport traffic control system  302  may periodically provide such information to airport tugs  202  at any suitable interval. 
       FIG.  4    shows an exemplary flow diagram  400  depicting various operations that may be performed by system  100  to facilitate, for example, airport tug  202 - 1  autonomously navigating airport facility  304 . At operation  402 , airport tug  202 - 1  may autonomously navigate airport facility  304 . In certain examples, such autonomous navigation at operation  402  may occur while airport tug  202 - 1  is not engaged with an aircraft. In certain additional or alternative examples, operation  402  may occur while airport tug  202 - 1  is engaged with and is transporting an aircraft at airport facility  304 . 
     At operation  404 , airport tug  202 - 1  monitors environmental conditions during autonomous navigation. For example, airport tug  202 - 1  may use one or more of sensors  216  to monitor environmental conditions in a vicinity of airport tug  202 - 1 . At operation  408 , airport tug  202 - 1  may determine whether there has been a change in the environmental conditions. For example, the change in the environmental conditions may include airport tug  202 - 1  detecting, in any suitable manner, that there is a baggage cart about to cross paths in front of airport tug  202 - 1  while airport tug  202 - 1  is traveling to a terminal to engage with an aircraft. If the answer at operation  406  is “No,” the flow may return to operation  402  and airport tug  202 - 1  may continue to navigate autonomously (e.g., along a route autonomously determined by airport tug  202 - 1 ). 
     If the answer at operation  406  is “Yes,” the flow may proceed to operation  408  and airport tug  202 - 1  may autonomously adjust movement of airport tug  202 - 1  based on the change. For example, in response to detecting of the baggage cart, airport tug  202 - 1  may decrease speed and stop any suitable distance away from the baggage cart to avoid a collision. 
       FIG.  5    shows another exemplary flow diagram  500  depicting various operations that may be performed by system  100  to facilitate, for example, airport tug  202 - 1  autonomously navigating airport facility  304 . At operation  502 , airport tug  202 - 1  may be in a standby mode during which airport tug  202 - 1  is available to be used in any suitable manner such as described herein. At operation  504 , airport tug  202 - 1  may determine whether airport tug  202 - 1  is needed, for example, to transport an aircraft at airport facility  304 . Such a determination may be made in any suitable manner. For example, airport tug  202 - 1  may receive an instruction from airport traffic control system  302  that indicates that a particular one of aircraft  204  at a particular terminal at airport facility  304  is ready to be transported. If the answer at operation  504  is “No,” the flow may return to operation  502 . 
     If the answer at operation  504  is “Yes,” airport tug  202 - 1  may travel to the aircraft at operation  506 . For example, airport tug  202 - 1  may travel to an indicated terminal, gate, etc. where aircraft  204 - 1  is located and is indicated as being ready for transport. In certain examples, airport tug  202 - 1  may autonomously travel to aircraft  204 - 1 . In certain alternative examples, airport tug  202 - 1  may travel to aircraft  204 - 1  under control of a remote operator. For example, the remote operator may be a pilot in a cockpit of the aircraft transported by airport tug  202 - 1 . Alternatively, the remote operator may be a human operator located in a control tower of airport facility  304 . 
     At operation  508 , airport tug  202 - 1  may attach to aircraft  204 - 1  in any suitable manner. In certain examples, airport tug  202 - 1  may autonomously engage coupling potion  218  of airport tug  202 - 1  with receiving portion  220  of aircraft  204 - 1 . Alternatively, airport tug  202 - 1  may be controlled by a remote operator or a human rider to attach airport tug  202 - 1  to aircraft  204 - 1 . 
     At operation  510 , airport tug  202 - 1  may transport (e.g., autonomously, semi-autonomously (e.g., using an adaptive cruise control function), or by way of remote control) aircraft  204 - 1  from a starting position to a designated delivery position at airport facility  304 . To illustrate an example,  FIG.  6    shows an exemplary view  600  of an airport facility where airport tug  202 - 1  may be used to transport aircraft  204 - 1  from a gate at a terminal of an airport facility to a predefined position on a runway. As shown in  FIG.  6   , a starting position  602  is indicated by a dashed circle at the terminal and a designated departure position  604  is indicated as another dashed circle on a runway. Designated departure position  604  represents a position where aircraft  204 - 1  is cleared to begin accelerating on the runway for takeoff. A dashed line  606  represents a route that airport tug  202 - 1  may generate and follow to autonomously transport aircraft  204 - 1  to designated departure position  604 . Dashed line  606  is depicted in  FIG.  6    for illustrative purposes to show an exemplary route that airport tug may take. It is understood that dashed line  606  may not actually be visible on the tarmac of the airport facility depicted in  FIG.  6   . Moreover, it is understood that the route depicted by dashed line  606  may change dynamically as conditions on the tarmac change. For example, a baggage cart may obstruct the route depicted by dash line  606  after the route is plotted by airport tug  202 - 1 . In response, airport tug  202 - 1  may generate an updated route to avoid the baggage cart. 
     Returning to  FIG.  5   , airport tug  202 - 1  may release from aircraft  204 - 1  upon arrival at the designated delivery position. In examples where the designated delivery position corresponds to a designated departure position, airport tug  202 - 1  may then travel any suitable distance from aircraft  204 - 1  such that aircraft  204 - 1  is cleared for takeoff. In certain examples, such a release may be performed autonomously by airport tug  202 - 1 . Alternatively, the release may be performed by way of direction from a remote operator in, for example, the cockpit of aircraft  204 - 1  or the control tower at the airport facility. 
     At operation  514 , airport tug  202 - 1  makes another determination whether airport tug  202 - 1  is needed. For example, the determination may be made based on airport tug  202 - 1  receiving an additional instruction from air traffic control system  302  that, for example, aircraft  204 - 2  is ready for transport (e.g., at an additional terminal, at the end of a runway post-landing, etc.). Based on the additional instruction, the answer at operation  514  is “Yes,” the flow returns to operation  506 , and airport tug  202 - 1  travels to the aircraft. If the answer at operation  514  is “No,” the flow returns to operation  502  where airport tug  202 - 1  returns to a standby mode. 
       FIG.  7    shows an exemplary flow diagram  700  depicting various operations that may be performed by system  100  in implementations where an airport tug such as airport tug  202 - 1  is electrically powered. At operation  702 , airport tug  202 - 1  may be charging at a charging position. Such a charging position may be configured in any suitable manner. For example, the charging position may correspond to a designated location at airport facility  304  that has charging cables, inductive charging pads, or any other suitable charging mechanism configured to charge the batteries of an electrically powered airport tug. 
     At operation  704 , airport tug  202 - 1  may determine whether airport tug  202 - 1  is needed. If the answer at operation  704  is “No,” the flow may return to operation  704  and airport tug  202 - 1  may continue to charge or wait at the charging position. In certain examples, airport tug  202 - 1  may only leave the charging position when summoned if airport tug  202 - 1  has sufficient power for a requested delivery operation. In such examples, system  100  may determine in any suitable manner whether airport tug  202 - 1  has sufficient power for a requested delivery operation. If airport  202 - 1  is not sufficiently charged for the requested delivery operation, airport tug  202 - 1  may remain at the charging position and an additional airport tug that is sufficiently charged may be selected (e.g., from a list of available airport tugs) for the requested delivery operation. 
     If the answer at operation  704  is “Yes,” (e.g., due to an instruction provided by airport traffic control system  302 ) the airport tug may autonomously travel to a terminal where, for example, aircraft  204 - 1  is located. At operation  708 , airport tug  202 - 1  may autonomously attach to aircraft  204 - 1  in any suitable manner. At operation  710 , airport tug  202 - 1  may autonomously transport aircraft  204 - 1  to a designated departure position. 
     At operation  712 , airport tug  202 - 1  may autonomously release from aircraft  204 - 1  upon arrival at the designated departure position. Airport tug  202 - 1  may then autonomously navigate away from aircraft  204 - 1  to clear aircraft  204 - 1  for departure. 
     At operation  714 , airport tug  202 - 1  may determine whether airport tug  202 - 1  is needed. If the answer at operation  714  is “Yes,” the flow may proceed to operation  706  and airport tug  202 - 1  may travel to an additional aircraft. If the answer at operation  714  is “No,” the flow may proceed to operation  702  and airport tug  202 - 1  may return to the charging position to recharge batteries of airport tug  202 - 1 . 
     In certain examples, airport tugs such as those described herein may be configured to switch between autonomous navigation at an airport facility and remote control navigation as directed by a remote operator. A remote operator may correspond to any human operator that is not riding on the airport tug. For example, a remote operator may correspond to a pilot in an aircraft being transported by the airport tug, an air traffic controller in a control tower, or a grounds crew member. 
     System  100  may determine when to switch airport tug  202  from autonomous navigation to remote control navigation based on satisfaction of a predefined condition. In certain examples, system  100  may automatically switch to remote control navigation based on satisfaction of the predefined condition. In certain alternative implementations, system  100  may determine that the predefined condition has been satisfied and then provide any suitable notification indicating that remote control operation is available unless otherwise recommended in a given situation. 
     The predefined condition may correspond to any suitable condition that may trigger remote control operation of airport tugs  202 . For example, in certain implementations, the predefined condition may correspond to a user input provided by a user that wants to remotely control one of airport tugs  202 . In such examples, the user input may be provided in any suitable manner by a remote operator. For example, a pilot in a cockpit of an airplane that is to be transported by one of airport tugs  202  may provide a user input by way of a control interface of the airplane or by way of a dedicated remote control device to assume control of one of airport tugs  202 . The pilot may then remotely control movement of the airport tug by way of any suitable control interfaces of the aircraft or by way of a dedicated remote control device operated by the pilot while within the cockpit of the aircraft. 
     In certain examples, the predefined condition may be associated with a change in engagement status of the airport tug. For example, the airport tug may automatically switch from operating autonomously to remote control operation upon being connected to or disconnected from an aircraft. 
     In certain examples, the predefined condition may be associated with an airport tug entering a predefined area at an airport facility. For example, an area at a gate of a terminal may correspond to a predefined area where an airport tug is configured to automatically switch from operating autonomously to remote control operation. In such examples, an airport tug may be controlled as directed by remote operator while in the predefined area to attach the coupling portion of the airport tug to a receiving portion of an aircraft. Once attached, the airport tug may be configured to automatically transport the aircraft in any suitable manner such as described herein. 
     In certain examples, the predefined condition may be associated with conditions in the environment at an airport facility. For example, certain weather conditions (e.g., rain, fog, sleet, snow, etc.) may trigger an airport tug switching from autonomous navigation to remote control navigation. In such examples, the airport tug may determine based on sensor data or other information that the weather conditions are unsafe for autonomous navigation. Such a determination may be made at any suitable time. For example, such a determination may be made while the airport tug is autonomously transporting an aircraft from a starting position to a designated departure position at the airport. The airport tug may then provide any suitable notification to, for example, the pilot of the aircraft being transported to indicate that remote control operation of the airport tug is recommended. 
     In addition, certain traffic conditions at an airport facility may trigger an airport tug switching from autonomous navigation to remote control navigation. For example, there may be a long queue of airplanes taxiing toward a runway and waiting in line for clearance to take off, which may make autonomous operation of the airport tug difficult. In such examples, the airport tug may provide any suitable notification to, for example, an air traffic controller to indicate that remote control operation of the airport tug is recommended. 
     In certain examples, system  100  may switch from remote control operation to autonomous operation of an airport tug based on system  100  detecting satisfaction of an additional predefined condition that triggers autonomous operation of the airport tug. Based on the satisfaction of the additional predefined condition, the airport tug may switch from navigating the airport facility as directed by a remote operator to navigating the airport facility autonomously. The additional predefined condition may correspond to any suitable condition that may trigger autonomous operation of an airport tug. For example, a remote operator may provide any suitable user input to direct an airport tug to begin autonomous operation at an airport facility. In certain alternative implementations, an airport tug may automatically switch back to autonomous operation upon being disengaged from an aircraft. 
       FIG.  8    shows an exemplary flow diagram  800  that depicts various operations that may be performed in an alternative implementation where an airport tug is controlled as directed by a remote operator while taxiing. At operation  802 , for example, airport tug  202 - 1  may be charging at a charging position. At operation  804 , a determination is made in any suitable manner such as described herein whether airport tug  202 - 1  is needed. If the answer at operation  804  is “No,” the flow returns to operation  802 . If the answer at operation  804  is “Yes,” the flow proceeds to operation  806  and airport tug  202 - 1  autonomously travels to an indicated terminal where, for example, aircraft  204 - 1  is located. 
     At operation  808 , airport tug  202 - 1  may attach to aircraft  204 - 1 . This may be performed in any suitable manner, for example, either autonomously or as directed by a remote operator. At operation  810 , a pilot may remotely control airport tug  202 - 1  from the cockpit of aircraft  204 - 1  to taxi aircraft  204 - 1  to a designated departure position. In such an example, the pilot may provide any suitable user input to assume control of the airport tug. Alternatively, airport tug  202  may automatically switch from autonomous navigation to remote control navigation upon being attached to aircraft  204 - 1 . While the pilot remotely controls airport tug  202 - 1 , the engines of aircraft  204 - 1  are not used to propel the aircraft towards the designated departure position. Rather, airport tug  202 - 1  provides all of the motive power to transport aircraft  204 - 1 . In so doing, it is possible to beneficially reduce fuel consumption by aircraft  204 - 1  and reduce noise made by aircraft  204 - 1  while taxiing. 
     At operation  812 , the pilot directs airport tug  202 - 1  to release from aircraft  204 - 1  in preparation for takeoff. In such examples, airport tug  202 - 1  may autonomously navigate away from aircraft  204 - 1  to clear aircraft  204 - 1  for departure. At operation  814 , a determination is made whether airport tug  202 - 1  is needed. If the answer at operation  814  is “Yes,” the flow returns to operation  806  and airport tug  202 - 1  may autonomously navigate to another terminal or any other suitable location where, for example, aircraft  204 - 3  is located. If the answer at operation  814  is “No,” the flow may return to operation  802  and airport tug  202 - 1  may autonomously navigate to the charging position at the airport facility. 
     In certain examples, airport tugs such as those described herein may be configured to be inductively charged while the airport tugs move around an airport facility or otherwise transport aircraft at the aircraft facility. In such examples, inductive charging coils or pads may be embedded in any suitable manner within the tarmac and along routes that airport tugs typically travel. With such a configuration, the airport tugs may be configured to operate continuously without having to, for example, return to a designated charging position after one or more trips transporting aircraft. 
     In certain examples, airport tugs such as those described herein may be used (e.g., autonomously, by way of a remote operator, or a human driver) to pull baggage car trains around the tarmac, or other tarmac uses. For example, the airport tug may be fitted with other useful equipment to aid in situations that may be dangerous or undesirable for humans. For example, an electrically powered, autonomous airport tug outfitted with fire suppression equipment could charge into a jet-fuel consuming fiery crash without risking a human firefighter’s life. Not only would risk to a human firefighter be reduced, but the airport tug may be able to arrive more quickly than a human fire crew, use its sensors to “see” things a human firefighter might not be able to easily see (e.g., thermal imaging cameras spotting crash survivors through smoke and wreckage) and be able to drive into the fire and wreckage to apply fire retardant at places a human firefighter may not be able to safely go. An airport tug with these kinds of capabilities could also be piloted at a distance as directed by human firefighters to facilitate suppressing a fire, assessing a crash scene, and/or helping crash survivors. 
       FIG.  9    illustrates an exemplary method  900  of operation of an airport tug (e.g., airport tug  202 ). While  FIG.  9    illustrates exemplary operations according to one embodiment, other embodiments may add to and/or modify the operations shown in  FIG.  9   . The operations shown in  FIG.  9    may be performed by an airport tug, any components included therein, and/or any implementation thereof. 
     At operation  902 , the airport tug may monitor, based on sensor data collected by way of one or more sensors of the airport tug, environmental conditions in a vicinity of the airport tug. Operation  902  may be performed in any of the ways described herein. 
     At operation  904 , the airport tug may autonomously navigate, based on the monitoring of the environmental conditions and while a coupling portion of the airport tug is engaged with a receiving portion of an aircraft, an airport facility to transport the aircraft from a starting position to a designated departure position at the airport facility or transport an arriving aircraft from the runway to a designated terminal for disembarkation. Operation  904  may be performed in any of the ways described herein. 
     In some examples, a non-transitory computer-readable medium storing computer-readable instructions may be provided in accordance with the principles described herein. The instructions, when executed by a processor of a computing device, may direct the processor and/or computing device to perform one or more operations, including one or more of the operations described herein. Such instructions may be stored and/or transmitted using any of a variety of known computer-readable media. 
     A non-transitory computer-readable medium as referred to herein may include any non-transitory storage medium that participates in providing data (e.g., instructions) that may be read and/or executed by a computing device (e.g., by a processor of a computing device). For example, a non-transitory computer-readable medium may include, but is not limited to, any combination of non-volatile storage media and/or volatile storage media. Exemplary non-volatile storage media include, but are not limited to, read-only memory, flash memory, a solid-state drive, a magnetic storage device (e.g., a hard disk, a floppy disk, magnetic tape, etc.), ferroelectric random-access memory (RAM), and an optical disc (e.g., a compact disc, a digital video disc, a Blu-ray disc, etc.). Exemplary volatile storage media include, but are not limited to, RAM (e.g., dynamic RAM). 
       FIG.  10    illustrates an exemplary computing device  1000  that may be specifically configured to perform one or more of the processes described herein. As shown in  FIG.  10   , computing device  1000  may include a communication interface  1002 , a processor  1004 , a storage device  1006 , and an input/output (I/O) module  1008  communicatively connected one to another via a communication infrastructure  1010 . While an exemplary computing device  1000  is shown in  FIG.  10   , the components illustrated in  FIG.  10    are not intended to be limiting. Additional or alternative components may be used in other embodiments. Components of computing device  1000  shown in  FIG.  10    will now be described in additional detail. 
     Communication interface  1002  may be configured to communicate with one or more computing devices. Examples of communication interface  1002  include, without limitation, a wired network interface (such as a network interface card), a wireless network interface (such as a wireless network interface card), a modem, an audio/video connection, and any other suitable interface. 
     Processor  1004  generally represents any type or form of processing unit capable of processing data and/or interpreting, executing, and/or directing execution of one or more of the instructions, processes, and/or operations described herein. Processor  1004  may perform operations by executing computer-executable instructions  1012  (e.g., an application, software, code, and/or other executable data instance) stored in storage device  1006 . 
     Storage device  1006  may include one or more data storage media, devices, or configurations and may employ any type, form, and combination of data storage media and/or device. For example, storage device  1006  may include, but is not limited to, any combination of the non-volatile media and/or volatile media described herein. Electronic data, including data described herein, may be temporarily and/or permanently stored in storage device  1006 . For example, data representative of computer-executable instructions  1012  configured to direct processor  1004  to perform any of the operations described herein may be stored within storage device  1006 . In some examples, data may be arranged in one or more location databases residing within storage device  1406 . 
     I/O module  1008  may include one or more I/O modules configured to receive user input and provide user output. One or more I/O modules may be used to receive input for a virtual experience. I/O module  1008  may include any hardware, firmware, software, or combination thereof supportive of input and output capabilities. For example, I/O module  1008  may include hardware and/or software for capturing user input, including, but not limited to, a keyboard or keypad, a touchscreen component (e.g., touchscreen display), a receiver (e.g., an RF or infrared receiver), motion sensors, and/or one or more input buttons. 
     I/O module  1008  may include one or more devices for presenting output to a user, including, but not limited to, a graphics engine, a display (e.g., a display screen), one or more output drivers (e.g., display drivers), one or more audio speakers, and one or more audio drivers. In certain embodiments, I/O module  1408  is configured to provide graphical data to a display for presentation to a user. The graphical data may be representative of one or more graphical user interfaces and/or any other graphical content as may serve a particular implementation. 
     In some examples, any of the systems, computing devices, and/or other components described herein may be implemented by computing device  1000 . For example, memory  102  or memory  208  may be implemented by storage device  1006 , and processor  104  or processor  212  may be implemented by processor  1004 . 
     In the preceding description, various exemplary embodiments have been described with reference to the accompanying drawings. It will, however, be evident that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the scope of the invention as set forth in the claims that follow. For example, certain features of one embodiment described herein may be combined with or substituted for features of another embodiment described herein. The description and drawings are accordingly to be regarded in an illustrative rather than a restrictive sense.