Patent Description:
Documents <CIT>, <CIT> and <CIT> relate to methods and systems for detecting an intruder aircraft position, retrieving intruder characteristics, predicting the location and intensity of associated wake vortices, calculating a future trajectory of the host aircraft, comparing host aircraft trajectory with locations of wake vortices and warning the host aircraft in case of conflict.

Modern aircraft include a range of different protection systems, such as the terrain avoidance and warning system (TAWS). The TAWS is an example of an onboard protection system designed to detect and alert when the aircraft is within a predetermined proximity to static physical objects (e.g. to the ground, or a ground-mounted structure, such as a building or communication tower).

An aircraft will typically have several systems capable of assessing altitude, from which height above the ground can be calculated or inferred. The typical TAWS arrangement employs an on-board database system that correlates aircraft latitude-longitude (lat-lon) position to a stored ground elevation. A GPS system (or other navigation reference system) provides the aircraft's current lat-lon position, which is used to access the database to look up the ground elevation at the aircraft's position or in the aircraft's flight path. If the aircraft's flight path will take it too close to the ground (or a structure erected on the ground), the TAWS alerts the pilot and may also invoke other safety systems or autopilot systems that form part of the aircraft's protection system.

Another potential obstacle to flight is wake turbulence created by other aircraft in flight. Wake turbulence includes several components that disturb the air in the wake of the flying aircraft. Of the components, the wingtip vortices or wake vortices typically dissipate the slowest and remain hazardous to flight of other aircraft for the longest time after the wake generating aircraft is gone.

Wake vortices result from the forces that lift the aircraft. High pressure air from the lower surface of the wings flows around the wingtips to the lower pressure region above the wings. The movement of the higher pressure air to the lower pressure region generates a pair of counter-rotating vortices that are shed from the wings. As viewed from behind the aircraft, the right wing vortex rotates counterclockwise and the left wing vortex rotates clockwise. This region of rotating air behind the aircraft is where wake turbulence occurs. The strength of the vortex (e.g., rotational velocity and size) is generally determined by the configuration, weight, wingspan, and speed of the vortex generating aircraft.

Because these vortices exist behind the generating aircraft, conventional wake avoidance techniques rely on the pilot to consider where the generating aircraft has been in the past to know what areas may contain wake vortices, and attempt to avoid those areas. Although this reactive wake avoidance can work, it depends on the pilot being aware of where other aircraft are, and where their wake vortices are likely to travel.

Accordingly, there is room for improvement. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.

Avionics systems, aircraft, and methods are provided.

In one embodiment, an avionics system for a subject aircraft is provided, according to claim <NUM>.

In another embodiment, a method of avoiding wake turbulence in a subject aircraft is provided, according to claim <NUM>. points in time to identify a wake conflict; and maneuvering the subject aircraft based on the wake conflict.

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations. Thus the particular choice of drawings is not intended to limit the scope of the present disclosure.

In general, the embodiments described herein provide algorithms by which a subject aircraft may predict future conflicts with wake vortices that may or may not have already been generated by an intruder aircraft. The algorithms may predict a path and future location of the wake vortices generated by the intruder aircraft. By then modeling a potential path that the subject aircraft may fly, the algorithms may predict whether the potential path conflicts with the yet to be generated wake vortices. Predicting the conflict allows the subject aircraft to disfavor the potential path and favor a different potential path in which the turbulence experienced by the subject aircraft is reduced.

The disclosed wake vortex prediction system may be implemented as part of flight path predictive techniques to provide unified, full-envelope protection, working across the entire spectrum of aircraft flight conditions to address a full spectrum of different types of hazards. Flight path predictions are computed continuously from the aircraft's current situation using a kinematic energy model. Plural predicted trajectories are calculated, each representing a different escape route that will avoid a hazard when the threshold or trigger point for that hazard is reached. The system respects different types of hazards, some dealing with innate aircraft properties, such as speed and altitude limits, and some dealing with external concerns, such as terrain and object avoidance. The disclosed aircraft flight envelope protection system is designed to work across all such threat envelope boundaries.

Although plural trajectories are calculated, the envelope protection system continually assesses, and deprecates trajectories that are not feasible in the aircraft's current situation. A deprecated trajectory is treated by the system as not viable, unless the aircraft's situation changes such that the deprecated trajectory again becomes viable. The disclosed protection system works in the background, and does not override or usurp the pilot's authority until only one viable predicted trajectory remains (all other predicted trajectories have been deprecated), and a threat is triggered. In this event, the protection system automatically deploys an autopilot mechanism to take evasive action to avoid the hazard condition. The protection system may also generate warnings to the pilot, but is preferably not dependent on the pilot to take recovery action once the one remaining viable trajectory reaches the trigger point.

Preferably, the predictive envelope protection system is configured to provide a non-binary spectrum of recovery actions, including a passenger-safe, soft-ride recovery at one end of the spectrum and a hard recovery at the other end of the spectrum. When required to avert imminent threat, the system triggers a hard recovery. In less extreme situations where there is more time to recover, the system triggers a soft recovery-a passenger safe, smooth recovery. When such soft recovery is triggered the system will optionally blend input from the pilot into the recovery algorithm, allowing the pilot to modify the recovery aggressiveness based on the pilot's skill and experience.

Referring now to <FIG>, a scenario <NUM> with an example of a subject aircraft <NUM> is illustrated in accordance with some embodiments. Aircraft <NUM> is flying in proximity to an intruder aircraft <NUM> and wake vortices <NUM> generated by intruder aircraft <NUM>. As used herein, the term "subject" is a name used only to differentiate aircraft <NUM> from intruder aircraft <NUM> for clarity of description, and implies no specific configuration in the claims other than the configuration recited therein. Although aircraft <NUM> is described in this description as an airplane, it should be appreciated that the systems described herein may be utilized in other aircraft, land vehicles, water vehicles, space vehicles, or other machinery without departing from the scope of the present disclosure. For example, the algorithms described herein may be applied to protect a vertical take-off and landing (VTOL) transport from the wake of a high speed train or to protect a fragile spacecraft from the high velocity exhaust of another spacecraft.

Referring now to <FIG>, and with continued reference to <FIG>, an avionics and flight controls system <NUM> is illustrated in accordance with some embodiments. Avionics and flight controls system <NUM> is disposed on aircraft <NUM> and includes a processor <NUM>, an aircraft detection system <NUM>, and actuators <NUM>. Processor <NUM> is programmed to operate aircraft <NUM> and to evaluate at least one potential trajectory <NUM>, as will be described in further detail below. Processor <NUM> has an associated memory circuit <NUM> that is configured according to a predetermined threat data structure 120a that stores a plurality of different types of threats associated with aircraft <NUM>. Although the format of data structure 120a is predetermined, the data stored in data structure 120a is dynamic. Data structure 120a includes all of the information needed to determine a size and position of wake vortex <NUM> at various points in time. In the example provided, data structure 120a stores a time value <NUM>, an aircraft type or weight and wingspan <NUM>, a position of intruder aircraft <NUM>, and a velocity of intruder aircraft <NUM>. The data structure may comprise a table, list, or matrix of records each corresponding to a different threat type. In the example provided, the threat type is the presence of a wake vortex obstacle.

The memory circuit <NUM> is also configured to support a trajectory coordinates data structure 120b that stores potential trajectories of subject aircraft <NUM> in terms of the space <NUM> and time <NUM> variables. For illustration purposes, the spacetime coordinate variables have been identified using a rectangular coordinate system (x, y, z, t). Other coordinate systems (e.g., spherical) may also be used.

At each point in time <NUM>, data structure 120b also stores aircraft state <NUM> variables that correspond to the state of subject aircraft <NUM> at each future point in time listed as time variable <NUM>. For example, aircraft state <NUM> variables may include aircraft altitude, specific energy, airspeed, pitch attitude, etc.. In some embodiments, processor <NUM> may consider the state variables <NUM> to determine whether aircraft <NUM> can withstand flying through a portion of wake vortex <NUM> with an acceptable level of disturbance to aircraft <NUM>. In some embodiments, wake vortex <NUM> is treated as a hard obstacle to be entirely avoided until an acceptable level of dissipation is predicted.

Aircraft detection system <NUM> includes one or more devices configured to detect intruder aircraft <NUM>. In the example provided, aircraft detection system <NUM> includes an Aircraft Dependent Surveillance-Broadcast (ADS-B) radio and a Traffic Collision Avoidance System (TCAS) system. ADS-B and TCAS receive signals generated by intruder aircraft <NUM> indicating the presence of intruder aircraft <NUM>. For example, aircraft detection system <NUM> may receive position and velocity data generated as an ADS-B transmission from intruder aircraft <NUM>. Additionally or alternatively, aircraft detection system <NUM> may receive a transponder signal from a TCAS system onboard intruder aircraft <NUM>. In some embodiments, aircraft detection system <NUM> includes LIDAR, RADAR, optical cameras, thermal cameras, ultrasonic sensors, and/or other sensors and other systems configured to detect intruder aircraft <NUM> even when intruder aircraft <NUM> is not generating an ADS-B or TCAS signal.

Actuator system <NUM> includes one or more actuator devices that control one or more vehicle features. For example, actuator system <NUM> may include actuators that manipulate control surfaces on aircraft <NUM>, extend or retract landing gear of aircraft <NUM>, an/or move other components of aircraft <NUM>. Actuator system <NUM> may be used for autopilot control of subject aircraft <NUM>.

In general, the algorithms described herein predict the motion path of the wake of the intruder aircraft. The wake moves in time so it is a four dimensional problem. In addition to predicting where in space the wake will be, the algorithms predict when in time the wake will be in that spot. Any segment of the wake has <NUM> characteristics: it has a width and a height that grows over time, an intensity that dissipates over time, and a lateral and vertical position that follows the wind and moves downward below the original path. There are two prongs to this prediction. The first is to propagate in time the wake that has already been created. The second prong is to predict the future path of the intruder aircraft so the wake that has not yet been created can be modeled.

Referring now to <FIG>, and with continued reference to <FIG>, an operative scenario <NUM> is illustrated in which a method <NUM> is performed by processor <NUM>. Processor <NUM> executes instructions and tasks to avoid intruder aircraft <NUM> and wake <NUM> of intruder aircraft <NUM>. The instructions may include one or more separate programs, each of which comprises an ordered listing of executable instructions for implementing logical functions. The instructions, when executed by the processor, receive and process signals from the aircraft detection system, perform logic, calculations, methods and/or algorithms for automatically controlling the components of aircraft <NUM>, and generate control signals for actuator system <NUM> to automatically control the components of aircraft <NUM> based on the logic, calculations, methods, and/or algorithms. Although only one processor <NUM> is illustrated, embodiments may include any number of processors <NUM> or subdivisions of processor <NUM> that communicate over any suitable communication medium or a combination of communication media and that cooperate to process sensor signals, perform logic, calculations, methods, and/or algorithms, and generate control signals to automatically control features of aircraft <NUM>. In various embodiments, one or more instructions, when executed by the processor, models possible recoveries of the aircraft and tests those recoveries for conflicts with predicted positions of wake vortex <NUM>.

As used herein, the term "intruder aircraft" means any aircraft within a predetermined range. The range may be expressed as a physical distance, a communications range of an Aircraft Dependent Surveillance-Broadcast (ADS-B) signal, a range associated with a Traffic Collision Avoidance System (TCAS) system, a visual range associated with an optical camera, or any other suitable range for detecting an aircraft that may become an obstacle or whose wake vortex may become an obstacle.

Processor <NUM> evaluates a first potential trajectory <NUM> and a second potential trajectory <NUM> for conflicts with a predicted wake vortex <NUM> generated by intruder aircraft <NUM> at a predicted position <NUM>, as illustrated in <FIG>. In the example illustrated, processor <NUM> is evaluating potential trajectories <NUM> and <NUM> at a specific time t in which subject aircraft <NUM> is predicted to be at position <NUM> along first potential trajectory <NUM> and to be at position <NUM> along second potential trajectory <NUM>. At time t processor <NUM> predicts intruder aircraft <NUM> will be at predicted position <NUM> and predicted wake vortex <NUM> will have a newly estimated portion <NUM> and multiple previously estimated wake vortex portions <NUM>, <NUM>, and <NUM>, as will be described below.

In the example provided, processor <NUM> performs tasks associated with method <NUM>. For example, processor <NUM> determines a likely magnitude and location of wake vortices, applying compensation for local wind and predicting future location of vortices and intruder aircraft. In some embodiments, processor <NUM> considers a <NUM>-dimensional wake vortex time-location as well as an aircraft <NUM>-D time-location as an obstacle to avoid. For example, intruder aircraft <NUM> and wake <NUM> may be treated the same as terrain or other obstacles to be avoided during flight for avoidance actions.

Processor <NUM> identifies an intruder aircraft <NUM> at task <NUM>. In the example provided, processor <NUM> identifies intruder aircraft <NUM> using intruder aircraft detection system <NUM>. For example, the intruder aircraft detection device may be a cooperative avoidance communication system configured to receive path intent data from the intruder aircraft. The cooperative avoidance communication system may utilize Traffic Collision Avoidance System (TCAS), Aircraft Dependent Surveillance-Broadcast (ADS-B), or other systems that provide intruder aircraft position. In some embodiments, the information obtained includes type, speed, and track of intruder aircraft <NUM>.

Processor <NUM> predicts a future path of the intruder aircraft <NUM> at task <NUM>. For example, processor <NUM> may use a current speed and a current position of intruder aircraft <NUM> to predict where intruder aircraft <NUM> will go in the future. In some embodiments, processor <NUM> is programmed to predict the future path of the intruder aircraft based on the path intent data from the cooperative avoidance communication system.

Processor <NUM> increments a time value of a predictive model in task <NUM>. For example, processor <NUM> may advance a time value to time t for calculation of position and aircraft state variables that may exist at time t. Processor <NUM> calculates a potential trajectory with potential positions of the subject aircraft at each of the future points in time in task <NUM>. For example, processor <NUM> may calculate that subject aircraft <NUM> will be at future position <NUM> at time t when following potential trajectory <NUM> and/or may calculate that subject aircraft <NUM> will be at future position <NUM> at time t when following potential trajectory <NUM>.

Processor <NUM> predicts a next position of intruder aircraft <NUM> at task <NUM>. For example, processor <NUM> may use a current speed and a current position of intruder aircraft <NUM> to predict that intruder aircraft <NUM> will be at predicted position <NUM> at time t.

Processor <NUM> generates a newly estimated portion of the wake vortex at the intruder aircraft at the current time value along the future path at task <NUM>. In combination with task <NUM>, task <NUM> causes processor to generate newly estimated portions at each of the future points in time as the time value increments. For example, the size, strength, and location of a wake vortex portion <NUM> created by intruder aircraft <NUM> having weight and speed characteristics of intruder aircraft <NUM> may be retrieved by a table lookup of known wake vortex strengths that have been previously determined.

Previous time value wake vortex portions are increased in size and decreased in strength at task <NUM>. For example, the "newly estimated portion" calculated at t-<NUM> may be increased in size and decreased in strength by predetermined dissipation rates to result in wake vortex portion <NUM>. Similarly, the "newly estimated portion" calculated at t-<NUM> may be increased in size and decreased in strength to result in wake vortex portion <NUM> and the "newly estimated portion" calculated at t-<NUM> may be increased in size and decreased in strength to result in wake vortex portion <NUM>. In the example provided, wake vortex portions <NUM>, <NUM>, <NUM>, and <NUM> are stored in obstacle data structure 120a to define positions associated with each of the future points in time in the obstacle data structure.

Alternative methods of adjusting the wake vortex <NUM> with time may be utilized without departing from the scope of the present disclosure. For example, processor <NUM> may calculate a predicted shape of wake vortex <NUM> and move the predicted shape within a terrain database based on the velocity of intruder aircraft <NUM> to predict the position of wake vortex <NUM>.

Processor <NUM> is programmed to at least partially estimate location characteristics of the wake vortex by adjusting a position of a previously estimated portion of the wake vortex based on a wind vector at task <NUM>. For example, processor <NUM> may move each of wake vortex portions <NUM>, <NUM>, and <NUM> by an amount corresponding to a measured wind vector. The wind vector may be obtained by sensors onboard subject aircraft <NUM>, obtained by weather data retrieved from weather services, or obtained by other suitable methods.

Processor <NUM> compares the potential positions with the strength, size, and location characteristics of the wake vortex at each of the future points in time to identify a wake conflict at task <NUM>. For example, processor <NUM> may determine that there is no wake conflict at position <NUM> if subject aircraft <NUM> follows potential trajectory <NUM> because the currently existing wake vortex <NUM> has dissipated and future wake vortex <NUM> does not extend to (i.e., will have dissipated at time t) at position <NUM>. Conversely, currently existing wake vortex <NUM> did not exist at position <NUM>, but will be identified as a wake vortex conflict because position <NUM> exists between future wake vortex portions <NUM> and <NUM>.

Task <NUM> sends method <NUM> to task <NUM> if a conflict exists or to task <NUM> if no conflict exists. Processor <NUM> deprecates or marks as unfavorable the potential trajectories that have a conflict at task <NUM>. For example, processor <NUM> may mark potential trajectory <NUM> as unfavorable while not marking potential trajectory <NUM> as unfavorable.

Processor <NUM> determines whether the potential trajectory currently being calculated is done being calculated at task <NUM>. For example, potential trajectory may be calculated a predetermined distance or a predetermined time away from the current position and time of subject aircraft <NUM>.

In the example provided, processor <NUM> is further programmed to maneuver the subject aircraft based on the wake conflict at least partially by flying the subject aircraft in response to marking the potential trajectory as unfavorable when the potential trajectory is a last trajectory of a plurality of potential trajectories to be marked unfavorable. In some embodiments, the avoidance is a speed change, turn, climb, descent, or combination thereof. In some embodiments, the avoidance is determined by the trajectories predicted by a trajectory prediction algorithm.

Claim 1:
An avionics system for a subject aircraft (<NUM>), the avionics system comprising:
an intruder aircraft detection device; and
a processor (<NUM>) programmed to:
identify an intruder aircraft (<NUM>) using the intruder aircraft detection device;
predict a future path of the intruder aircraft (<NUM>);
estimate strength, size, and location characteristics of a wake vortex created by the intruder aircraft (<NUM>) at past, present, and future points in time along the intruder aircraft's past, present, and future path;
calculate a trajectory with positions of the subject aircraft (<NUM>) at each of the past, and present points in time and with potential positions of the subject aircraft (<NUM>) at each of the future points in time;
compare the positions with the estimated strength, size, and location characteristics of the wake vortex to identify a wake conflict; and
manoeuvre the subject aircraft (<NUM>) based on the wake conflict.