WO2012145608A1

WO2012145608A1 - Systems and methods for autonomously landing an aircraft

Info

Publication number: WO2012145608A1
Application number: PCT/US2012/034422
Authority: WO
Inventors: David W. Vos; Damien B. JOURDAN
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-04-20
Filing date: 2012-04-20
Publication date: 2012-10-26
Anticipated expiration: 2013-10-20

Abstract

A system for autonomously landing an aircraft may include a controller configured to control the aircraft, identify a landing destination for landing the aircraft, and land the aircraft at the landing destination. A computer-implemented method for autonomously landing an aircraft may include controlling the aircraft via a processor, identifying a landing destination for landing the aircraft via the processor, and landing the aircraft at the landing destination via the processor. An aircraft may include a system for autonomously landing the aircraft, the system including a controller configured to control the aircraft, identify a landing destination for landing the aircraft, and landing the aircraft at the landing destination.

Description

SYSTEMS AND METHODS FOR AUTONOMOUSLY LANDING AN AIRCRAFT

DESCRIPTION

Claim of Priority

[001] This PCT International Patent Application claims the benefit of priority of U.S. Provisional Application No. 61/477,459, filed April 20, 2011 , the disclosure of which is incorporated herein by reference.

Field of the Description

[002] This description relates to systems and methods for autonomously controlling an aircraft. In particular, this description relates to systems and methods for autonomously landing an aircraft without the assistance of a pilot, for example, when the aircraft is unmanned, the pilot becomes unable to control the aircraft, or the aircraft experiences a technical problem that compromises normal operation of its control systems.

Background

[003] There are many situations in which it would be desirable for an aircraft to have a system that would automatically control the aircraft upon a lapse of control. For example, it would be desirable for an aircraft to have a system that would automatically take control and/or land the aircraft without the assistance of a pilot. For example, if the pilot is operating an unmanned aircraft remotely, the remote signal to control the aircraft may not reach the aircraft or the aircraft may be damaged or malfunctioning in a manner that prevents its remote control. In addition, it would be desirable to automatically control and land an aircraft when a pilot becomes incapable of landing the aircraft, for example, due to a medical emergency or interference from someone aboard the aircraft. Yet another situation in which it would be desirable to automatically control an aircraft is when in general aviation, a pilot flying alone becomes incapacitated and unable to pilot the aircraft. In such a situation, it would be desirable to automatically land the aircraft at an appropriate airport without the assistance of the incapacitated pilot. [004] Another situation in which it would be desirable to automatically control and land an aircraft is when the aircraft's control system suffers damage or a malfunction. In such a situation, control of the aircraft may be compromised to the extent that the manner by which the aircraft is controlled must account for the damage or malfunction. For example, if the aircraft were to lose a portion of a control surface, such as a flap, aileron, wing, rudder, or tail, it may be desirable to alter the way in which the aircraft is controlled in order to compensate for the damage or malfunction, for example, by changing the flight control envelope. Such situations may occur, for example, when an aircraft collides with another aircraft, when one or more engines cut-out, when an engine ingests birds or debris, or when an engine breaks apart, sending pieces of the engine into the aircraft, which may lead to damage of control surfaces and/or systems.

[005] Further, it would be desirable for such a system to automatically control and land the aircraft at an appropriate airport using a combination of autonomous control and navigation systems. In addition, as aviation begins to combine unmanned aircraft and manned aircraft in common airspace, it may be desirable to provide systems and methods to improve the safe operation of both unmanned and manned aircraft in the common airspace.

SUMMARY

[006] In accordance with one aspect, a system for autonomously landing an aircraft may include a controller configured to automatically control the aircraft, identify a landing destination for landing the aircraft, and land the aircraft at the landing destination. According to a further aspect, a computer-implemented method for autonomously landing an aircraft may include automatically controlling the aircraft via a processor, identifying a landing destination for landing the aircraft via the processor, and landing the aircraft at the landing destination via the processor.

According to still a further aspect, an aircraft may include a system for autonomously landing the aircraft, the system comprising a controller configured to automatically control the aircraft, identify a landing destination for landing the aircraft, and land the aircraft at the landing destination.

[007] According to another aspect, the system may be configured to be activated by at least one of a switch (e.g., a pushbutton) for activating the system and signals received from a location remote from the aircraft. According to a further aspect, the controller may be configured to automatically send signals alerting at least one of air traffic control, airports in the vicinity of the aircraft, and airplanes in the vicinity of the aircraft of an emergency landing of the aircraft. According to another aspect, the controller may be configured to automatically return the aircraft to stable flight following loss of control of the aircraft. In yet another aspect, the controller may be configured to automatically control the aircraft such that the aircraft loiters for a period of time prior to landing. According to another aspect, the controller may be configured to automatically control the aircraft based on

information relating to at least one of a location of the closest suitable destination for landing, terrain features, weather, and prohibited airspace.

[008] According to yet another aspect, the controller may be configured to determine a sequence of maneuvers for landing the aircraft and executing the sequence of maneuvers. The sequence of maneuvers may include a plurality of flight trajectories. The flight trajectories may include at least one of an arc, a straight portion, a spiral, and flaring for landing. According to a further aspect, the controller may be configured to automatically reduce airspeed of the aircraft prior to landing by inducing yaw and roll.

[009] According to still another aspect, the controller may be configured to land the aircraft without power from an engine. According to another aspect, the controller may be configured to diagnose damage or a malfunction related to at least one of control surfaces and control systems of the aircraft. The controller may be configured to alter flight dynamic constraints of the aircraft based on the diagnosis. The controller may be configured to alter the flight dynamic constraints by reducing a flight envelope of the aircraft based on the diagnosis. Reducing the flight envelope may include at least one of increasing a minimum turn radius of the aircraft, restricting direction of turns of the aircraft, reducing a maximum bank angle of the aircraft, increasing minimum airspeed of the aircraft, and increasing landing speed of the aircraft.

[010] According to a further aspect, the controller may be configured to control an aircraft with an aileron frozen in a neutral position, with an aileron free- floating, with an aileron detached from the aircraft, with between about 40 percent and about 80 percent of a wing area moment missing and with an associated aileron missing, and/or with a stabilator and associated rudder frozen in a neutral position. The aircraft may be a manned or unmanned aircraft.

[011] Additional aspects of the invention may be set forth in part in the description which follows or may be learned by practice of the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[012] Fig. 1 is a perspective view of an exemplary embodiment of an aircraft.

[013] Fig. 2 is pictorial representation of an exemplary embodiment of a cockpit instrument panel.

[014] Fig. 3 is a block diagram of an exemplary embodiment of a control architecture according to an exemplary embodiment of a control system for autonomously controlling and/or landing an aircraft.

[015] Fig. 4 is a three-dimensional graphical representation of a flight path following an exemplary automatic recovery of control of an aircraft following an upset of control.

[0 6] Fig. 5 is a two-dimensional graphical representation of a flight path following an exemplary automatic recovery of control of an aircraft following an upset of control.

[017] Fig. 6 is a graphical representation of a flight path following an exemplary automatic recovery of control of an aircraft following damage to the aircraft.

[018] Fig. 7 is a graphical representation of an exemplary adjustment to increase autopilot gain following damage to the aircraft to regain flight control.

[019] Fig. 8A is a graphical representation of roll tracking during an exemplary recovery of stable flight following damage to the aircraft.

[020] Fig. 8B is a graphical representation of effective aileron command during an exemplary recovery of stable flight following damage-induced roll.

[021] Fig. 9A is a three-dimensional graphical representation of a flight path according to an exemplary autonomous landing sequence. [022] Fig. 9B is a two-dimensional graphical representation of a flight path according to the exemplary autonomous landing sequence shown in Fig. 9A.

[023] Fig. 10A is a two-dimensional graphical representation of North-East position tracking during an exemplary engine-out autonomous landing sequence.

[024] Fig. 10B is a two-dimensional graphical representation of altitude tracking during the exemplary engine-out autonomous landing sequence shown in Fig. 10A.

[025] Fig. 10C is a two-dimensional graphical representation of beta tracking during the exemplary engine-out autonomous landing sequence shown in Fig. 10A.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

[026] Reference will now be made in detail to a number of exemplary embodiments of the invention, which may be illustrated in drawings incorporated into this description.

[027] Fig. 1 shows an exemplary embodiment of an aircraft 10 that may include a system that, according to some embodiments, may automatically land the aircraft 10 by taking over control of aircraft 10, automatically stabilizing its flight, and automatically and safely landing the aircraft 10 at a suitable landing destination. The aircraft 10 shown in Fig. 1 is exemplary only, and the systems and methods described herein may be incorporated into any type of manned or unmanned aircraft known to those skilled in the art.

[028] The exemplary aircraft 10 includes a fuselage 12, including a cockpit 14 for a pilot and passengers, and a tail section 16. The aircraft 10 includes wings 18 attached to the fuselage 12, and a horizontal stabilizer 20 and a vertical stabilizer 22 located at the tail section 16. The wings 18 include ailerons 24. The horizontal stabilizer 20 includes a pair of elevators 26, and the vertical stabilizer 22 includes a rudder 28. During flight, the aircraft 10 may be controlled to rotate with respect to three axes X, Y, and Z by operation of the ailerons 24, elevators 26, and rudder 28. For example, movement of the ailerons 24 may result in rotation with respect to the X-axis (i.e., roll), movement of the elevators 26 may result in rotation with respect to the Y-axis (i.e., pitch), and movement of the rudder 28 may result in rotation with respect to the Z-axis (i.e., yaw). It is contemplated that some aircraft may use fewer, additional, or different control surfaces to control rotation of the aircraft with respect to the X, Y, and Z axes.

[029] The exemplary aircraft 10 may include a system for autonomously or automatically landing an aircraft. According to some embodiments, the system may include an automatic flight control system or "autopilot system" including a controller 30 (see Fig. 1) configured to take over control of a manned or unmanned aircraft, automatically stabilize flight, and automatically and safely land the aircraft. The autopilot system may include any system that is configured to control both vertical- and horizontal-axis flight, such as airspeed, altitude, and glide slope in the vertical axis, and bank angle, side-slip, and heading in the horizontal axis.

[030] According to some embodiments, the autopilot system is configured to control the aircraft using cross-axis control, as explained in more detail below. According to some embodiments, the system is capable of automatically controlling and landing an aircraft that has suffered structural damage and/or damage or malfunction to its control systems. For example, the autopilot system may be capable of using roll/yaw/side-slip control to manipulate the aircraft's attitude, angle of attack, and side-slip, with respect to incoming airflow so that control of the aircraft is maintained in all of the X, Y, and Z axes (i.e., in roll, pitch, and yaw, respectively).

[031] Such a system may be used with military and civilian aircraft, and could be used by a pilot or passenger by activating a switch (e.g., by pushing a pushbutton 32 in cockpit 14 (see, e.g., Fig. 2)) to activate the system in case of emergency or appropriate situation. According to some embodiments, the system may be activated remotely (i.e., from outside the aircraft at, for example, an airport control tower or air traffic control facility) upon determination that it would be advisable to take over control of the aircraft and safely land it from a remote location. In such remotely operated systems, the system may be configured to be activated via radio or other signals received from the remote location. In addition, some embodiments of the system may be used with other technologies, for example, sense and avoidance technologies, to provide safe operation of manned and unmanned aircraft in common airspace.

[032] During exemplary operation, some embodiments may be activated in order to take over control of the aircraft and safely land the aircraft at the closest suitable landing destination, such as, for example, an airport, airfield, or other suitable location to conduct an emergency landing. For example, some embodiments of the system may be configured to automatically control the flight of the aircraft as outlined below.

[033] Upon occurrence of a problem rendering it advisable for the aircraft to safely land itself, the system may be activated by, for example, activation of a switch in the cockpit or remotely. Such a problem may be, for example, an inability of the pilot to control the aircraft due to health or other reasons, or a technical problem with the aircraft that compromises normal operation of its control systems.

[034] Once activated, some embodiments of the system may automatically send radio transmissions alerting air traffic control and airports and pilots of other aircraft in the vicinity of the aircraft in which the system has been activated. Such radio transmissions may be transmitted according to predetermined local protocols relating to appropriate radio frequencies and messages. For example, the system may automatically squawk, alerting the airspace in the vicinity that the aircraft is experiencing an emergency, including using air traffic towers and other aircraft in the vicinity.

[035] Upon activation, some embodiments of the system may automatically recover control of the aircraft and return it to stable controlled flight. For example, if the aircraft loses control due to pilot error or a technical problem, the system will automatically recover control and return the aircraft to stable controlled flight.

According to some embodiments, if the aircraft suffers from a technical problem, such as damage to its control surfaces or control systems, the system may automatically compensate for the damage and recover control of the aircraft.

[036] Once control has been recovered, some embodiments of the system may automatically control the aircraft so that it loiters for a period of time (e.g., one to five minutes, depending on the circumstances) before automatically landing at a suitable landing destination such as an airport or landing strip. This loitering permits other aircraft in the vicinity to clear the area and the airport to clear a runway for an emergency landing of the aircraft experiencing the problem. During loitering, the system may cause the aircraft to operate according to a predetermined flight path, such as, for example, a circling pattern or racetrack pattern. The system may also take into account other factors that might affect the flight path, such as, for example, terrain features such as mountains, approaching weather, and/or the presence of prohibited airspace. According to some embodiments, the system may continuously or intermittently receive information from outside sources and/or internal calculations, and update information relating to the closest suitable airport, terrain features, weather, and/or prohibited airspace. According to some embodiments, this information may be available to the pilot without activation of the system for autonomously controlling the aircraft.

[037] The system according to some embodiments may automatically determine a flight path for execution between the time of activation of the system and landing of the aircraft. This may include the above-mentioned loitering and

performing maneuvers according to a determined sequence of flight trajectories, such as, for example, a series of arcs and straight segments, followed by a

descending spiral, a straight segment, and a flare for landing. This may include automatically determining a trajectory and flight path for landing at the nearest suitable airport or otherwise suitable landing area.

[038] Upon determination of a flight path, the system according to some embodiments automatically controls flight of the aircraft and executes the flight path until a safe landing is achieved. According to some embodiments, the system uses the automatic flight control system, suitable navigation aids, such as, for example, a global positioning system (GPS) and/or an inertial navigation system (INS), and air data such as wind velocity including speed and direction, to fly the aircraft according to the determined flight path and land the aircraft. The wind velocity may be obtained from a service such as XM radio and/or the system may determine wind velocity internally by determining the difference between the ground speed and air speed of the aircraft using known methods.

[039] According to some embodiments, the system may maintain the descent profile of the flight path using cross-axis flight control, which may result in reducing the speed of the aircraft by inducing yaw and roll to create more drag. The induced yaw causes the aircraft to rotate slightly about its Z-axis, and the induced roll causes the aircraft to rotate slightly about its X-axis. The induced yaw causes the aircraft to crab such that the vertical stabilizer is not aligned with the forward direction of travel, and the induced roll counteracts the tendency of the aircraft to change course due to the induced yaw. As a result, the speed of the aircraft can be reduced while maintaining vertical axis flight, or flight along a straight path defined by the vertical axis. The system may use a combination of GPS, INS, and air data such as the wind velocity to control the aircraft during cross-axis flight control. Such control may permit a quicker descent to the elevation of the airport during an emergency situation.

[040] As the aircraft approaches the runway at the airport travelling along its descent according to its determined flight path, the system may control the aircraft to flare out and touchdown on the runway. Following touchdown, the system may control the travel of the aircraft on the ground so that it follows the runway in a generally straight path and causes the brakes to be applied until the aircraft comes to a controlled stop.

[041] The system may include a controller including an autopilot system that includes a computing system that may include one or more hardware and/or software components such as, for example, a central processing unit; a computer- readable storage medium, such as a random access memory module, a read-only memory module, storage, a database; one or more input/output devices; and an operator interface. The CPU may include one or more processors, each configured to execute instructions and process data to perform functions associated with the system. The CPU may be connected to the RAM, ROM, storage, database, input/output devices, and the operator interface. The CPU may be configured to execute computer program instructions stored on the computer-readable storage medium to perform various processes and methods consistent with certain disclosed embodiments. The computer program instructions may be loaded into the RAM for execution by the CPU or processed by other data processing units in communication with the CPU. An input/output device may include autopilot control inputs and aircraft sensors. The operator interface may be a cockpit display or a remote display. Although the exemplary controller 30 shown in Fig. 1 is depicted as a single controller located at a single position in aircraft 10, according to some embodiments, the controller may include a number of controllers that operate in a coordinated manner, and which may be located at different positions in the aircraft.

[042] According to the exemplary embodiment shown in Fig. 3, the system 40 may include, for example, four damage tolerant control (DTC) modules that enable operation of the exemplary system: an all-attitude control (AAC) module 42, a model reference adaptive control (MRAC) module 44, an automatic supervisory adaptive control (ASAC) module 46, and an emergency mission management system (EMMS) module 48.

[043] Each of the modules shown in Fig. 3 may be implemented with a distinct processing module having a processing unit (such as a CPU or

microcontroller) coupled to memory, input/output devices, and an interface. Other embodiments may implement each module in a software code module stored on a memory where the system operates or a single CPU with interacting software modules having the functionality as described herein. Those skilled in the art will also appreciate that additional embodiments implementing principles of the present invention may be a combination of hardware and software, depending on the operating environment for such an embodiment (e.g., a large aircraft, a micro-sized unmanned aircraft, etc.).

[044] According to the exemplary embodiment shown in Fig. 3, the EMMS 48 may diagnose airframe damage and/or control system malfunction, define maneuverability and flight envelope restrictions based on the airframe damage, and select an emergency landing profile (e.g., for an engine out landing). The ASAC 46 may provide automatic recovery from airframe damage and returns the aircraft to trimmed flight. The MRAC 44 may adjust autopilot gains to compensate for reduction in physical control authority of the aircraft. The AAC 42 controllers may track commands at any vehicle attitude, provide automatic recovery from attitude upsets, and maintain flight envelope limits.

[045] During exemplary operation, the EMMS 48 uses the output of the MRAC 44 and ASAC 46 as an indicator of damage to the aircraft. Using this information, the EMMS 48 updates the performance constraints or operating envelope of the aircraft. In particular, the damage to the aircraft may reduce its agility, and the EMMS 48 may reduce the maneuverability based on this information to account for any reduced agility. For example, the EMMS 48 may specify a greater turn radius, restrict turn direction, and/or specify maximum bank angle. The EMMS 48 may also reduce the flight envelope, for example, to increase the minimum airspeed and increase landing speed. The EMMS 48 may further search for feasible landing trajectories. Thus, if the aircraft is damaged or malfunctioning, the modules of the DTC, operating in concert, automatically stabilize flight and safely land the aircraft. [046] According to some embodiments, the AAC 42 converts Euler angle commands to body attitude errors. Outer-loop controllers operate in the Euler referential, and they generate Euler attitude commands ( <p_Cmd, 0_cmd, ψο κί) to track the trajectory of the aircraft. The AAC 42 converts the Euler attitude commands into the body referential (Φ_χ, Φ_γ, Φ_ζ). Inner-loop controllers operate in the body referential to generate control surface commands (e.g., commands for movement of an aileron, an elevator, and a rudder) (5_a, 5_e, δ_Γ). The ACC 42 may enable the aircraft to track any kinematically-feasible trajectory.

[047] The following examples highlight the automatic control provided by the ACC 42. According to a first example, an aircraft experienced an attitude upset of -60 degrees pitch and 45 degrees roll, while satisfying flow angle and load limitations. The AAC 42 took control of the aircraft and provided automatic recovery from the attitude upset, returning the aircraft to controlled, level flight. According to a second example shown in Fig. 4, the AAC 42 continuously tracked airspeed and altitude during aerobatic maneuvers including an aileron roll, split-S, and rolling circle.

[048] According to a third example shown in Fig. 5, the AAC 42

automatically returned an aircraft to level, controlled flight from uncontrolled roll flight, where the roll surfaces of the aircraft were frozen at neutral. The AAC 42 tracked airspeed and altitude with the aircraft navigating at a commanded loiter according to a circling pattern prior to landing on a runway 50.

[049] According to some embodiments, the MRAC 44 and ASAC 46 may provide resiliency to damage to the aircraft, such as, for example, airframe damage. For example, as illustrated in Fig. 6, upon damage to the aircraft, the ASAC 46 functions to return the aircraft to trimmed and controlled flight. For example, the ASAC 46 uses autopilot commands to monitor "trim margin." The ASAC 46 adjusts trim surfaces and mission commands to unwind saturated actuators. The MRAC 44 functions to recover the aircraft to baseline performance by, for example, comparing the observed performance of the aircraft to a reference model, and adjusting the autopilot gains according to the comparison. Thereafter, the system may operate to autonomously and safely land the damaged aircraft.

[050] Several examples highlight the ability of the ASAC 46 and MRAC 44 to automatically recover control of a damaged aircraft. In a first example, the aileron was frozen in the neutral position. The ASAC 46 recovered controllability, and the MRAC 44 automatically recovered performance for autonomous landing. In a second example, the aileron was free-floating. The ASAC 46 recovered

controllability, and the MRAC 44 automatically recovered performance for

autonomous landing. In a third example, the aileron was completely detached, the ASAC 46 recovered controllability, and the MRAC 44 automatically recovered performance for autonomous landing. In fourth through sixth examples, 40, 60, and 80 percent of the right wing area moment was missing, including the aileron. In such dire situations, the ASAC 46 recovered controllability, and the MRAC 44

automatically recovered performance for autonomous landing of the damaged aircraft.

[051] In a seventh example, the right stabilator and right rudder were simultaneously frozen at neutral. The MRAC 44 was demonstrated on the roll, pitch, and yaw channels of the aircraft, as shown in Fig. 7. As shown in Fig. 7, the MRAC 44 adjusted the autopilot to account for the damage by raising the elevator and rudder loop gains by a factor of about 2.

[052] Several examples highlight the capabilities of the ASAC 46 to recover aircraft control from various damaged conditions. Examples include 40 percent loss of wing area moment, 60 percent loss of wing area moment, and 80 percent loss of wing area moment. In a fourth example, stable flight was recovered by the ASAC 46 following 60 percent loss of wing area moment, 30 percent loss of stabilator, and 30 percent loss of vertical stabilizer.

[053] As shown in Figs. 8A and 8B, the ASAC 46 recovered control of the damaged aircraft. As shown in Fig. 8A, following damage, the ASAC 46

automatically issued a roll command to compensate for a damage-induced roll.

Thereafter, the ASAC 46 automatically adjusted the roll command in response to the damaged aircraft's recovery. As shown in Fig. 8B, the ASAC 46 automatically adjusted the effective aileron command to compensate for the damage-induced roll. As the damaged aircraft recovered, the ASAC 46 adjusted the effective aileron command to help maintain stabilized flight.

[054] According to some embodiments, the EMMS 48 uses the output of the MRAC 44 and ASAC 46 as an indicator of damage to the aircraft. Using this information, the EMMS 48 updates the flight dynamics constraints of the aircraft. In particular, the damage to the aircraft may reduce its agility, and the EMMS 48 reduces the maneuverability based on this information to account for any reduced agility. For example, the EMMS 48 may specify a greater turn radius, restrict turn direction, for example, so as to execute only slip inside turns, and/or specify a smaller maximum bank angle. The EMMS 48 may also reduce the flight envelope, for example, to increase the minimum airspeed and increase landing speed.

[055] According to some embodiments, the EMMS 48 may also search for emergency landing profiles. The EMMS 48 may continuously or intermittently search for feasible landing trajectories, for example, regardless of whether the aircraft is functioning properly (e.g., regardless of whether the engines are functioning properly, or with the engines not operating). For example, as shown in Figs. 9A and 9B, if the engine(s) of the aircraft cease functioning, the EMMS 48 may automatically identify a suitable airport (e.g., from information available from a suitable database, either stored aboard the aircraft or obtained from a remote location), automatically take control of the aircraft, and perform an autonomous landing according a sequence of trajectory elements.

[056] In the example shown in Figs. 9A and 9B, the EMMS 48 selects a trajectory composed of six components for autonomously landing the aircraft. First the EMMS 48 controls the aircraft through an arc (A1), followed in sequence by a first straight segment (D1), a second arc (A2), a spiral (S), a second straight segment (D2), and finally, a flare (F) for landing on a runway 50.

[057] Figs. 10A-10C respectively show North-East position, altitude, and beta tracking during a test of an engine-out, automatic landing on a runway 50 according to exemplary operation of the EMMS 48 system. As shown in Fig. 10A, after the engine cuts out, the EMMS 48 controls the aircraft through an autonomous landing trajectory, including in sequence, a first arc, a straight segment, a second arc, a spiral, a final straight segment and flare, at which point the aircraft lands. As shown in Figs. 10B and 10C, during the trajectory sequence, the system tracks the altitude and beta, permitting the system to provide appropriate AGL and beta commands for control of the aircraft. In this exemplary manner, upon damage to the aircraft, the EMMS 48 diagnoses the damage using the MRAC 44 and ASAC 46, updates the flight dynamics constraints based on the diagnosis, and performs an autonomous emergency landing by determining an emergency landing profile according to the damage and real-time attitude, position, and heading of the aircraft from various inputs.

[058] The exemplary systems and methods described herein may be used in either manned or unmanned aircraft, and in either military or civilian aircraft. In such environments, the systems and methods may be able to reduce the loss of unmanned and manned aircraft. Moreover, when used in combination with flight control redundancy, reliability and safety of flight may be dramatically increased. Furthermore, the described systems and methods may be used in manned and unmanned aircraft with fault-tolerant control, for example, when control surfaces and/or control systems of the aircraft are damaged or malfunction, to provide control which compensates for the damage or malfunction. In addition, the systems and methods may be used in manned aircraft to regain control following an upset to the flight of the aircraft. For example, a pilot, following an unexpected loss of control, may activate the system, for example, by activating a switch (e.g., a pushbutton) so that control is automatically regained. Similarly, if a pilot is incapacitated, a person not trained to control the aircraft, or not aboard the aircraft, could activate the system (e.g., via a pushbutton or signals from a remote source), thereby initiating the system to take control of the aircraft and autonomously land it at a suitable airport.

Additionally, when combined with sense and avoid technology, the systems and methods may facilitate safe convergence of manned and unmanned aviation in common airspace.

[059] Other embodiments of the invention will be apparent to those skilled in the art from consideration of the description and practice of the invention disclosed herein. It is intended that the description and examples be considered as exemplary only.

Claims

WHAT IS CLAIMED IS:

1. A system for autonomously landing an aircraft, the system comprising: a controller configured to:

control the aircraft;

identify a landing destination for landing the aircraft; and land the aircraft at the landing destination.

2. The system of claim 1 , wherein the system is configured to be activated by at least one of a switch for activating the system and signals received from a location remote from the aircraft.

3. The system of claim 1 , wherein the controller is configured to send signals alerting at least one of air traffic control, airports in the vicinity of the aircraft, and airplanes in the vicinity of the aircraft of an emergency landing of the aircraft.

4. The system of claim 1 , wherein the controller is configured to return the aircraft to stable flight following loss of control of the aircraft.

5. The system of claim 1 , wherein the controller is configured to control the aircraft such that the aircraft loiters for a period of time prior to landing.

6. The system of claim 5, wherein the controller is configured to control the aircraft based on information relating to at least one of a location of the closest suitable destination for landing, terrain features, weather, and prohibited airspace.

7. The system of claim 1 , wherein the controller is configured to determine a sequence of maneuvers for landing the aircraft and execute the sequence of maneuvers.

8. The system of claim 7, wherein the sequence of maneuvers comprises a plurality of flight trajectories.

9. The system of claim 8, wherein the plurality of flight trajectories comprises at least one of an arc, a straight portion, a spiral, and flaring for landing.

10. The system of claim 1 , wherein the controller is configured to reduce airspeed of the aircraft prior to landing by inducing yaw and roll.

11. The system of claim 1 , wherein the controller is configured to land the aircraft without power from an engine.

12. The system of claim 1 , wherein the controller is configured to diagnose damage or malfunction related to at least one of control surfaces and control systems of the aircraft, and alter flight dynamic constraints of the aircraft based on the diagnosis.

13. The system of claim 12, wherein the controller is configured to alter the flight dynamic constraints by reducing a flight envelope of the aircraft based on the diagnosis, and wherein reducing the flight envelope comprises at least one of increasing a minimum turn radius of the aircraft, restricting direction of turns of the aircraft, reducing a maximum bank angle of the aircraft, increasing minimum airspeed of the aircraft, and increasing landing speed of the aircraft.

14. The system of claim 1 , wherein the controller is configured to control the aircraft with an aileron in an uncontrollable state, wherein the uncontrollable state of the aileron comprises at least one of the aileron being frozen in a neutral position, the aileron being free-floating, and the aileron being detached from the aircraft.

15. The system of claim 1 , wherein the controller is configured to control the aircraft with between about 40 percent and about 80 percent of a wing area moment missing and with an associated aileron missing.

16. The system of claim 1 , wherein the controller is configured to control the aircraft with a stabilator and associated rudder frozen in a neutral position.

17. The system of claim 1 , wherein the aircraft is an unmanned aircraft.

18. A computer-implemented method for autonomously landing an aircraft, the method comprising:

controlling the aircraft via a processor;

identifying a landing destination for landing the aircraft via the processor; and landing the aircraft at the landing destination via the processor.

19. The method of claim 18, further comprising activating the method via at least one of a switch in the aircraft and signals received from a location remote from the aircraft.

20. The method of claim 18, further comprising sending signals via the processor alerting at least one of air traffic control, airports in the vicinity of the aircraft, and airplanes in the vicinity of the aircraft of an emergency landing of the aircraft.

21. The method of claim 18, further comprising returning the aircraft via the processor to stable flight following loss of control of the aircraft.

22. The method of claim 18, further comprising controlling the aircraft via the processor such that the aircraft loiters for a period time prior to landing.

23. The method system of claim 22, wherein controlling the aircraft via the processor is based on information relating to at least one of a location of the closest suitable destination for landing, terrain features, weather, and prohibited airspace.

24. The method of claim 18, further comprising determining via the processor a sequence of maneuvers for landing the aircraft and executing the sequence of maneuvers via the processor.

25. The method of claim 24, wherein the sequence of maneuvers includes a plurality of flight trajectories.

26. The method of claim 25, wherein the plurality of flight trajectories includes at least one of an arc, a straight portion, a spiral, and flaring for landing.

27. The method of claim 18, wherein controlling the aircraft comprises inducing yaw and roll via the processor to reduce airspeed of the aircraft prior to landing the aircraft.

28. The method of claim 18, wherein landing the aircraft comprises landing the aircraft without power from an engine of the aircraft.

29. The method of claim 18, further comprising diagnosing via the processor damage or malfunction related to at least one of control surfaces and control systems of the aircraft, and altering via the processor flight dynamic constraints of the aircraft based on the damage or malfunction.

30. The method of claim 29, wherein altering the flight dynamic constraints comprises reducing a flight envelope of the aircraft based on the damage or malfunction, and wherein reducing the flight envelope comprises at least one of increasing a minimum turn radius of the aircraft, restricting direction of turns of the aircraft, reducing a maximum bank angle of the aircraft, increasing minimum airspeed of the aircraft, and increasing landing speed of the aircraft.

31. The method of claim 18, wherein controlling the aircraft via the processor comprises at least one of controlling the aircraft with an aileron frozen in a neutral position, controlling the aircraft with an aileron free-floating, and controlling the aircraft with an aileron detached from the aircraft.

32. The method of claim 18, wherein controlling the aircraft via the processor comprises controlling the aircraft with between about 40 percent and about 80 percent of a wing area moment missing and with an associated aileron missing.

33. The method of claim 18, wherein controlling the aircraft via the processor comprises controlling the aircraft with a stabilator and associated rudder frozen in a neutral position.

34. The method of claim 18, wherein the aircraft is an unmanned aircraft.

35. An aircraft comprising:

a system for autonomously landing the aircraft, the system comprising:

a controller configured to:

control the aircraft;

36. The aircraft of claim 35, wherein the system is configured to be activated by at least one of a switch for activating the system and signals received from a location remote from the aircraft.

37. The aircraft of claim 35, wherein the controller is configured to send signals alerting at least one of air traffic control, airports in the vicinity of the aircraft, and airplanes in the vicinity of the aircraft of an emergency landing of the aircraft.

38. The aircraft of claim 35, wherein the controller is configured to return the aircraft to stable flight following loss of control of the aircraft.

39. The aircraft of claim 35, wherein the controller is configured to control the aircraft such that the aircraft loiters for a period of time prior to landing.

40. The aircraft of claim 39, wherein the controller is configured to control the aircraft based on information relating to at least one of a location of the closest suitable destination for landing, terrain features, weather, and prohibited airspace.

41. The aircraft of claim 35, wherein the controller is configured to determine a sequence of maneuvers for landing the aircraft and execute the sequence of maneuvers.

42. The aircraft of claim 41 , wherein the sequence of maneuvers comprises a plurality of flight trajectories.

43. The aircraft of claim 42, wherein the plurality of flight trajectories comprises at least one of an arc, a straight portion, a spiral, and flaring for landing.

44. The aircraft of claim 35, wherein the controller is configured to reduce airspeed of the aircraft prior to landing by inducing yaw and roll.

45. The aircraft of claim 35, wherein the controller is configured to land the aircraft without power from an engine.

46. The aircraft of claim 35, wherein the controller is configured to diagnose damage or malfunction related to at least one of control surfaces and control systems of the aircraft, and alter flight dynamic constraints of the aircraft based on the diagnosis.

47. The aircraft of claim 46, wherein the controller is configured to alter the flight dynamic constraints by reducing a flight envelope of the aircraft based on the diagnosis, and wherein reducing the flight envelope comprises at least one of increasing a minimum turn radius of the aircraft, restricting direction of turns of the aircraft, reducing a maximum bank angle of the aircraft, increasing minimum airspeed of the aircraft, and increasing landing speed of the aircraft.

48. The aircraft of claim 35, wherein the controller is configured to control the aircraft with an aileron in an uncontrollable state, wherein the uncontrollable state of the aileron comprises at least one of the aileron being frozen in a neutral position, the aileron being free-floating, and the aileron being detached from the aircraft.

49. The aircraft of claim 35, wherein the controller is configured to control the aircraft with between about 40 percent and about 80 percent of a wing area moment missing and with an associated aileron missing.

50. The aircraft of claim 35, wherein the controller is configured to control the aircraft with a stabilator and associated rudder frozen in a neutral position.

51. The aircraft of claim 35, wherein the aircraft is an unmanned aircraft.