UAV forced landing control method, device, equipment and storage medium

Abstract

The embodiment of the present application discloses a method, device, equipment and storage medium for controlling forced landing of a drone. The method determines whether the first unit residual energy of the target drone is greater than the unit boundary energy when the target drone loses power; if the first unit residual energy is less than or equal to the unit boundary energy, the target drone is controlled to fly to the forced landing point according to a first control strategy; during the flight of the target drone to the forced landing point, it is determined whether the first indicated airspeed of the target drone is less than or equal to the parachute opening speed threshold; if the first indicated airspeed is less than or equal to the parachute opening speed threshold, the target drone is controlled to continue to fly to the forced landing point in a predetermined posture for a preset time according to a second control strategy, and then the target drone is controlled to enter the parachute opening recovery process. The technical problem of unstable forced landing of drones in the prior art is solved, and the stability of the forced landing process of drones is improved.

Description

Technical Field

[0001] The present application relates to the field of drone control technology, and in particular to a drone forced landing control method, device, equipment and storage medium. Background Art

[0002] In the development history of drones, since there is no direct pilot control, drones can not only avoid pilot casualties, but also break through the physiological limitations of the human body, fully tapping the flight potential of the aircraft; at the same time, compared with manned aircraft, drones have lower costs and strong adaptability to harsh environments. Therefore, drone technology has developed rapidly since its birth.

[0003] In the current aviation field, for drones, the importance of flight control strategies and air-gliding forced landing capability estimation becomes more prominent due to the lack of timely feedback and operation from pilots. When a drone has an engine failure in the air and loses power, its controllability drops sharply, and it is unable to continue its flight mission or even return to the field normally in some cases, which may cause significant losses to surrounding property and threaten the safety of nearby personnel. Therefore, how to improve the stability of drone forced landing is an urgent problem to be solved in this field. Summary of the invention

[0004] The main purpose of this application is to provide a UAV forced landing control method, device, equipment and storage medium, aiming to solve the technical problem of how to improve the stability of UAV forced landing in the prior art.

[0005] To achieve the above objectives, the present application provides a method for controlling a forced landing of a UAV, comprising:

[0006] When the target UAV loses power, determining whether the first unit remaining energy of the target UAV is greater than the unit boundary energy;

[0007] If the first unit residual energy is less than or equal to the unit boundary energy, the target UAV is controlled to fly toward the forced landing point according to a first control strategy; wherein the first control strategy includes: controlling the longitudinal heading of the target UAV according to a pitch angle airspeed control mode, and controlling the lateral heading of the target UAV according to a track tracking mode;

[0008] During the flight of the target UAV toward the forced landing point, determining whether the first indicated airspeed of the target UAV is less than or equal to a parachute opening speed threshold;

[0009] If the first indicated airspeed is less than or equal to the allowable parachute opening speed threshold, the target UAV is controlled to continue flying towards the forced landing point in a predetermined posture for a preset time according to a second control strategy, and then the target UAV is controlled to enter a parachute opening and recovery process; wherein the second control strategy includes: controlling the longitudinal heading of the target UAV according to a pitch angle control mode and a roll angle control mode; and controlling the lateral heading of the target UAV according to the track tracking mode.

[0010] Optionally, after the step of determining whether the first unit remaining energy of the target UAV is greater than the unit boundary energy, the method further includes:

[0011] If the first unit residual energy is greater than the unit boundary energy, controlling the target UAV to fly toward the forced landing point according to the first control strategy;

[0012] When the target UAV is at a preset distance from the forced landing circling radius, determining whether the second unit remaining energy of the target UAV is greater than the unit boundary energy;

[0013] If the second unit residual energy is less than or equal to the unit boundary energy, the target UAV is controlled to continue to fly toward the forced landing point according to the first control strategy; and in the process of the target UAV continuing to fly toward the forced landing point, it is determined whether the first relative height of the target UAV is lower than the ideal parachute opening height or whether the first waiting flight distance of the target UAV is less than the recovery distance;

[0014] If the first relative altitude is lower than the ideal parachute opening altitude or the first waiting distance to be flown is less than the recovery distance, the target UAV is controlled to fly toward the forced landing point according to the third control strategy; and when the second indicated airspeed is less than or equal to the allowable parachute opening speed threshold, the target UAV is controlled to continue to fly toward the forced landing point according to the predetermined attitude for the preset time according to the second control strategy, and then the target UAV is controlled to enter the parachute opening and recovery process; wherein the third control strategy includes: controlling the longitudinal heading of the target UAV according to the altitude holding control mode, and controlling the lateral heading of the target UAV according to the track tracking mode.

[0015] Optionally, after the step of determining whether the second unit remaining energy of the target UAV is greater than the unit boundary energy when the target UAV is at a preset distance from the forced landing circling radius, the method further includes:

[0016] If the second unit residual energy is greater than the unit boundary energy, controlling the target UAV to hover around the forced landing point according to the forced landing hovering radius according to the first control strategy;

[0017] During the hovering process, continuously determining whether the third unit remaining energy of the target UAV is greater than the unit boundary energy;

[0018] If the third unit residual energy is less than or equal to the unit boundary energy, the target UAV is controlled to continue to fly toward the forced landing point according to the first control strategy; and in the process of the target UAV continuing to fly toward the forced landing point, it is determined whether the second relative height of the target UAV is lower than the ideal parachute opening height or whether the second waiting flight distance of the target UAV is less than the recovery distance;

[0019] If the second relative altitude is lower than the ideal altitude for parachute opening or the second distance to be flown is less than the recovery distance, the target UAV is controlled to fly toward the forced landing point according to the third control strategy; and when the third indicated airspeed is less than or equal to the allowable parachute opening speed threshold, the target UAV is controlled to continue flying toward the forced landing point in the predetermined posture for the preset time according to the second control strategy, and then the target UAV is controlled to enter the parachute opening and recovery process.

[0020] Optionally, the expression of the pitch angle airspeed control mode includes:

[0021]

[0022]

[0023] θ g =θ ref +θ NAV

[0024]

[0025] in, is the transfer function of the filter in the control circuit of the pitch angle airspeed control mode, s is a complex parameter, a is the parameter of the filter, δ e is the equivalent elevator deflection, q is the pitch rate, q g is the pitch rate, θ is the pitch angle, θ g is the pitch angle, θ ref is the pitch angle feedforward, θ NAV is the pitch angle calculated by the guidance law, is the indicated airspeed given, V IAS is the indicated airspeed, is the gain of each controller in the control circuit of the pitch angle airspeed control mode.

[0026] Optionally, the expression of the pitch angle control mode includes:

[0027]

[0028] Among them, δ e is the equivalent elevator deflection, θ g is the given value of the pitch angle, θ is the pitch angle, It is the gain of each controller in the control circuit of the pitch angle control mode.

[0029] Optionally, the expression of the roll angle control mode includes:

[0030]

[0031] Among them, δ a is the equivalent aileron deflection, φ g is the given value of the roll angle, φ is the roll angle, is the gain of each controller in the control circuit of the roll angle control mode.

[0032] Optionally, the expression of the height control mode includes:

[0033]

[0034]

[0035] θ g =θ ref +θ NAV

[0036]

[0037]

[0038] Among them, δ e is the equivalent elevator deflection, q is the pitch rate, q g is the pitch rate, θ is the pitch angle, θ g is the pitch angle, θ ref is the pitch angle feedforward, H is the relative height of the UAV, is the lifting speed, H g is a given height, is the lifting speed given, is the gain of each controller in the control circuit of the height control mode.

[0039] In addition, to achieve the above purpose, the present application also provides a UAV forced landing control device, including:

[0040] A first judgment module is used to judge whether the first unit residual energy of the target UAV is greater than the unit boundary energy when the target UAV loses power;

[0041] A first control module is configured to control the target UAV to fly toward the forced landing point according to a first control strategy if the first unit residual energy is less than or equal to the unit boundary energy; wherein the first control strategy includes: controlling the longitudinal heading of the target UAV according to a pitch angle airspeed control mode, and controlling the lateral heading of the target UAV according to a track tracking mode;

[0042] A second judgment module is used to judge whether the first indicated airspeed of the target UAV is less than or equal to the parachute opening speed threshold during the flight of the target UAV to the forced landing point;

[0043] The second control module is used to control the target UAV to continue flying to the forced landing point in a predetermined posture for a preset time according to a second control strategy if the first indicated airspeed is less than or equal to the allowable parachute opening speed threshold, and then control the target UAV to enter the parachute opening and recovery process; wherein the second control strategy includes: controlling the longitudinal heading of the target UAV according to the pitch angle control mode and the roll angle control mode; and controlling the lateral heading of the target UAV according to the track tracking mode.

[0044] In addition, to achieve the above-mentioned purpose, the present application also provides a control device, which includes a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the above-mentioned method.

[0045] In addition, to achieve the above-mentioned purpose, the present application also provides a computer-readable storage medium, on which a computer program is stored, and a processor executes the computer program to implement the above-mentioned method.

[0046] The beneficial effects that can be achieved by this application.

[0047] The embodiment of the present application proposes a method, device, equipment and storage medium for controlling an unmanned aerial vehicle forced landing. The method determines whether the first unit residual energy of the target unmanned aerial vehicle is greater than the unit boundary energy when the target unmanned aerial vehicle loses power; if the first unit residual energy is less than or equal to the unit boundary energy, the target unmanned aerial vehicle is controlled to fly to the forced landing point according to a first control strategy; wherein the first control strategy includes: controlling the longitudinal heading of the target unmanned aerial vehicle according to a pitch angle airspeed control mode, and controlling the lateral heading of the target unmanned aerial vehicle according to a track tracking mode; during the flight of the target unmanned aerial vehicle to the forced landing point, determining whether the first indicated airspeed of the target unmanned aerial vehicle is less than or equal to a parachute opening speed threshold; if the first indicated airspeed is less than or equal to the parachute opening speed threshold, controlling the target unmanned aerial vehicle to continue to fly to the forced landing point according to a predetermined posture for a preset time according to a second control strategy, and then controlling the target unmanned aerial vehicle to enter a parachute opening and recovery process; wherein the second control strategy includes: controlling the longitudinal heading of the target unmanned aerial vehicle according to a pitch angle control mode and a roll angle control mode; and controlling the lateral heading of the target unmanned aerial vehicle according to the track tracking mode. That is, the method provides a new method for forced landing of UAVs based on energy management. For UAVs that have lost power, the method performs real-time energy evaluation on them and realizes stable control of forced landing of UAVs according to different control strategies based on the energy status of the UAVs. The method solves the technical problem of unstable forced landing of UAVs in the prior art and improves the stability of the forced landing process of UAVs. At the same time, based on the coordination of energy management and forced landing points, the forced landing control method can accurately control the forced landing point of UAVs and improve safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A schematic diagram of the control device structure of the hardware operating environment involved in the embodiment of the present application;

[0049] Figure 2 A schematic diagram of a flow chart of a method for controlling forced landing of a UAV according to an embodiment of the present application;

[0050] Figure 3 This is a schematic diagram of the control circuit structure of the pitch angle airspeed control mode in the embodiment of the present application;

[0051] Figure 4 This is a schematic diagram of the control circuit structure of the track tracking control mode in the embodiment of the present application;

[0052] Figure 5 This is a schematic diagram of the control circuit structure of the pitch angle control mode in the embodiment of the present application;

[0053] Figure 6 This is a schematic diagram of the control circuit structure of the roll angle control mode in an embodiment of the present application;

[0054] Figure 7 A schematic diagram of a flow chart of another method for controlling forced landing of a UAV according to an embodiment of the present application;

[0055] Figure 8 A schematic diagram of a flow chart of another method for controlling forced landing of a UAV according to an embodiment of the present application;

[0056] Fig. 9 A schematic diagram of a forced landing route involving hovering of a target UAV in an embodiment of the present application;

[0057] Fig.10 This is a schematic diagram of the functional modules of the UAV forced landing control device according to an embodiment of the present application.

[0058] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0059] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0060] The main solution of the embodiment of the present application is: when the target UAV loses power, it is determined whether the first unit residual energy of the target UAV is greater than the unit boundary energy; if the first unit residual energy is less than or equal to the unit boundary energy, the target UAV is controlled to fly to the forced landing point according to the first control strategy; wherein the first control strategy includes: controlling the longitudinal heading of the target UAV according to the pitch angle airspeed control mode, and controlling the lateral heading of the target UAV according to the track tracking mode; during the flight of the target UAV to the forced landing point, it is determined whether the first indicated airspeed of the target UAV is less than or equal to the allowed parachute opening speed threshold; if the first indicated airspeed is less than or equal to the allowed parachute opening speed threshold, the target UAV is controlled to continue to fly to the forced landing point in a predetermined posture for a preset time according to the second control strategy, and then the target UAV is controlled to enter the parachute opening and recovery process; wherein the second control strategy includes: controlling the longitudinal heading of the target UAV according to the pitch angle control mode and the roll angle control mode; and controlling the lateral heading of the target UAV according to the track tracking mode.

[0061] For drones, the importance of flight control strategies and air taxiing and forced landing capability estimation becomes more prominent due to the lack of timely feedback and operation from pilots. When a drone has an engine failure in the air and loses power, its controllability drops sharply, and it is unable to continue its flight mission or even return to the field normally in some cases, which may cause significant damage to surrounding property and threaten the safety of nearby personnel. Therefore, how to ensure flight stability and safely recover drones is an urgent problem to be solved in this field.

[0062] To this end, the present application provides a solution, a new method for forced landing of UAVs based on energy management, which performs real-time energy evaluation on UAVs that have lost power, and realizes stable control of forced landing of UAVs according to different control strategies based on the energy status of UAVs. The technical problem of unstable forced landing of UAVs in the prior art is solved, and the stability of the forced landing process of UAVs is improved; at the same time, based on the coordination of energy management and forced landing points, the forced landing control method can accurately control the forced landing point of UAVs and improve safety.

[0063] Reference Figure 1 , Figure 1 This is a schematic diagram of the control device structure of the hardware operating environment involved in the embodiment of the present application.

[0064] like Figure 1 As shown, the control device may include: a processor 1001, such as a central processing unit (CPU), a communication bus 1002, a user interface 1003, a network interface 1004, and a memory 1005. Among them, the communication bus 1002 is used to realize the connection and communication between these components. The user interface 1003 may include a display screen (Display), an input unit such as a keyboard (Keyboard), and the optional user interface 1003 may also include a standard wired interface and a wireless interface. The network interface 1004 may optionally include a standard wired interface and a wireless interface (such as a wireless fidelity (WIreless-FIdelity, WI-FI) interface). The memory 1005 may be a high-speed random access memory (Random Access Memory, RAM) memory, or a stable non-volatile memory (Non-Volatile Memory, NVM), such as a disk memory. The memory 1005 may also be a storage device independent of the aforementioned processor 1001.

[0065] Those skilled in the art will understand that Figure 1 The structure shown in the figure does not constitute a limitation on the control device, and may include more or less components than shown in the figure, or combine certain components, or arrange the components differently.

[0066] like Figure 1 As shown, the memory 1005 as a storage medium may include an operating system, a data storage module, a network communication module, a user interface module and an electronic program.

[0067] exist Figure 1In the control device shown, the network interface 1004 is mainly used for data communication with the network server; the user interface 1003 is mainly used for data interaction with the user; the processor 1001 and the memory 1005 in the control device of the present invention can be set in the control device, and the control device calls the drone forced landing control device stored in the memory 1005 through the processor 1001, and executes the drone forced landing control method provided in the embodiment of the present application.

[0068] The control device in this embodiment can be a control device on the UAV, which directly controls the UAV through communication; or it can be a ground device, which controls the UAV through radio.

[0069] Reference Figure 2 Based on the hardware device of the aforementioned embodiment, the embodiment of the present application provides a method for controlling forced landing of a UAV, including:

[0070] S20: When the target UAV loses power, determine whether the first unit residual energy of the target UAV is greater than the unit boundary energy.

[0071] In the specific implementation process, the target UAV refers to any UAV, and the loss of power means that the engine stops running due to engine failure or other reasons. The first unit of residual energy refers to the first unit of residual energy of the target UAV when it loses power. It can be understood that when the UAV loses power, its mass remains unchanged, so Among them, V c is the current indicated airspeed, H rel_c is the current relative height to the forced landing point. Unit boundary energy refers to the minimum energy that can support the target UAV to glide to the vicinity of the forced landing point. In this embodiment, Among them, V end Indicated airspeed for recovery target, H rel_end Relative height of the recovery target.

[0072] Therefore, it can be understood that judging whether the first unit residual energy of the target UAV is greater than the unit boundary energy is to judge whether the current energy of the target UAV can support air sliding to the vicinity of the forced landing point.

[0073] S40: If the first unit residual energy is less than or equal to the unit boundary energy, controlling the target UAV to fly toward the forced landing point according to a first control strategy.

[0074] In the specific implementation process, the forced landing point refers to the forced landing location of the UAV. It is understandable that, as a possible situation, if the first unit residual energy is less than or equal to the unit boundary energy, it means that the current target UAV has insufficient residual energy and needs to fly to the forced landing point as soon as possible to make a safe forced landing. Therefore, in the specific implementation process, it is necessary to control the target UAV to fly to the forced landing point according to the first control strategy. Among them, the first control strategy includes: controlling the longitudinal heading of the target UAV according to the pitch angle airspeed control mode, and controlling the lateral heading of the target UAV according to the track tracking mode.

[0075] As an implementation method, see Figure 3 , Figure 3 This is a schematic diagram of the control circuit structure of the pitch angle airspeed control mode, combined with Figure 3 It can be seen that the pitch angle airspeed control mode can achieve airspeed control by adjusting the pitch angle of the target UAV, using a proportional plus integral control structure to control the airspeed at a given airspeed. To achieve the control target, the proportional-integral control method is used to achieve the control of the longitudinal loop. Specifically, the main implementation steps of the pitch angle speed control mode include: ① receiving the indicated airspeed given value from the flight control computer ② Receive the indicated airspeed signal (V IAS ), pitch angle (θ), pitch angle rate (q); ③ Through the proportional integral controller closed loop longitudinal control loop, solve the control law and output the elevator deflection control signal, so as to achieve the indicated airspeed control of the target UAV. The specific formulas involved include:

[0076]

[0077]

[0078] θ g =θ ref +θ NAV

[0079]

[0080] in, is the transfer function of the filter in the control circuit of the pitch angle airspeed control mode, s is a complex parameter, a is the parameter of the filter, δ e is the equivalent elevator deflection, q is the pitch rate, q g is the pitch rate, θ is the pitch angle, θ g is the pitch angle, θ ref is the pitch angle feedforward, θ NAV is the pitch angle calculated by the guidance law, is the indicated airspeed given, V IASis the indicated airspeed, is the gain of each controller in the control circuit of the pitch angle airspeed control mode.

[0081] As an implementation method, see Figure 4 , Figure 4 This is a schematic diagram of the control circuit structure of the track tracking control mode. Figure 4 It can be seen that the track tracking control mode can adopt the proportional plus integral control method, with the side offset distance (Y) as the lateral main control outer loop, the roll angle (φ) as the inner loop control target, and the roll angle rate (p) and side offset speed (φ) as the inner loop control target. To increase damping, track the given roll angle target value (φ g ) to achieve track tracking control. Specifically, the main steps to achieve the track tracking control mode include: ① receiving the roll angle given value (φ) from the flight control computer g ) ; ② Receive the roll angle signal (p) and roll angular rate signal (p) from the sensor, and calculate the side offset distance (Y) and side deviation speed ③ Combining the above signals, the proportional integral controller closes the lateral and heading control loop, solves the control law and outputs the control signal to the actuator (aileron rudder) of the UAV system, thereby achieving the track tracking control of the target UAV. The specific formulas involved include:

[0082]

[0083] φ g =φ NAV

[0084]

[0085] in, and is the gain of each controller in the control circuit of the track tracking control mode.

[0086] S60: During the flight of the target UAV toward the forced landing point, determine whether the first indicated airspeed of the target UAV is less than or equal to a parachute opening speed threshold.

[0087] In the specific implementation process, the first indicated airspeed refers to the current flight speed of the drone, and the parachute opening speed threshold refers to the maximum indicated speed of the target drone at which the parachute is allowed to be opened. It is understandable that when the target drone is flying towards the forced landing point, when the indicated airspeed of the drone is less than or equal to the allowed parachute opening speed threshold, it means that the target drone needs to enter the parachute opening preparation state, otherwise there will be a risk of falling. Therefore, it is necessary to determine whether the first indicated airspeed of the target drone is less than or equal to the allowed parachute opening speed threshold during the flight of the target drone towards the forced landing point.

[0088] S80: If the first indicated airspeed is less than or equal to the allowable parachute opening speed threshold, the target UAV is controlled according to a second control strategy to continue flying toward the forced landing point in a predetermined posture for a preset time, and then the target UAV is controlled to enter a parachute opening recovery process.

[0089] In the specific implementation process, when the indicated airspeed of the drone is less than or equal to the threshold value of the parachute opening speed, it means that the target drone needs to enter the parachute opening preparation state. Therefore, it is necessary to control the target drone to continue to fly to the forced landing point in a predetermined posture according to the second control strategy. The predetermined posture refers to the state of the target drone flying in a fixed posture. Specifically, the pitch angle is controlled and maintained at 0 degrees. The preset time refers to the time to maintain the predetermined posture, which can be set according to the specific situation of the target drone, as long as it can meet the requirements of the stable flight state of the drone with the parachute opened. In this embodiment, the preset time can be 2s.

[0090] The second control strategy includes: controlling the longitudinal heading of the target UAV according to the pitch angle control mode and the roll angle control mode; and controlling the lateral heading of the target UAV according to the track tracking mode.

[0091] As an implementation method, see Figure 5 , Figure 5 This is a schematic diagram of the control circuit structure of the pitch angle control mode, combined with Figure 5 It can be seen that the pitch angle control mode can adopt the proportional plus integral control method, with the pitch angle (θ) as the longitudinal main control outer loop, tracking the given pitch angle target value (θ g ) to achieve longitudinal attitude control of the UAV. Specifically, the pitch angle control mode implementation steps include: ① receiving the pitch angle given value (θ_ref) from the flight control computer; ② receiving the pitch angle signal (θ) and pitch angle rate signal (q) from the sensor; ③ combining the above signals, through the proportional integral controller closed-loop lateral control loop, solving the control law and outputting the control signal to the actuator (elevator) of the UAV system, thereby achieving the control of the roll angle of the target UAV. The specific formulas involved include:

[0092]

[0093] Among them, δ e is the equivalent elevator deflection, θ g is the given value of the pitch angle, θ is the pitch angle, It is the gain of each controller in the control circuit of the pitch angle control mode.

[0094] As an implementation method, see Figure 6 , Figure 6This is a schematic diagram of the control circuit structure of the roll angle control mode, combined with Figure 6 It can be seen that the roll angle control mode can adopt the proportional integral control method, with the roll angle It is the main lateral control outer loop, tracking the given roll angle target value to achieve attitude control of the target UAV to the left, wings flat, and right. Specifically, the steps to achieve the roll angle control mode include: ① receiving the roll angle given value (φ) from the flight control computer g ) ; ② Receive the roll angle signal (φ) and roll rate signal (p) from the sensor; ③ Combine the above signals, solve the control law and output the control signal to the aileron rudder through the proportional integral controller closed loop lateral control loop, so as to achieve the roll angle maintenance and control of the target UAV. The specific formulas involved include:

[0095]

[0096] Among them, δ a is the equivalent aileron deflection, φ g is the given value of the roll angle, φ is the roll angle, is the gain of each controller in the control circuit of the roll angle control mode.

[0097] The above is a method for controlling the forced landing of a target UAV when the first unit residual energy of the target UAV is less than or equal to the unit boundary energy. The following introduces another case, that is, when the first unit residual energy of the target UAV is greater than the unit boundary energy, a method for controlling the forced landing of a target UAV.

[0098] In another embodiment, see Figure 7 After the step of determining whether the first unit remaining energy of the target UAV is greater than the unit boundary energy, the method further includes:

[0099] S302: If the first unit remaining energy is greater than the unit boundary energy, controlling the target UAV to fly toward the forced landing point according to the first control strategy;

[0100] In the specific implementation process, the first unit residual energy being greater than the unit boundary energy indicates that the energy is sufficient. In this embodiment, it can be further determined whether the first unit residual energy is greater than the unit correction energy, wherein the unit correction energy = unit boundary energy + loss energy. K loss It is determined by factors such as the drone's resistance, asymmetry, and external attachments. DTG is the straight-line distance from the drone's current position to the scheduled forced landing point, K is the lift-to-drag ratio at the current angle of attack, and E is the lift-to-drag ratio at the current angle of attack. turn_loss It is the unit energy consumed when the drone turns 90°.

[0101] It is understandable that when the energy is sufficient, the airspeed requirement for opening the parachute cannot be reached before landing. However, in order to ensure the safety of the forced landing of the target drone as much as possible, in this case, the target drone should be moved closer to the forced landing point as soon as possible to prevent the target drone from being unable to land at the forced landing point in the correct posture due to insufficient energy. Therefore, in this embodiment, the target drone can still be controlled to fly to the forced landing point according to the first control strategy.

[0102] S304, when the target UAV is at a preset distance from the forced landing circling radius, determining whether the second unit remaining energy of the target UAV is greater than the unit boundary energy;

[0103] In the specific implementation process, the forced landing circling radius refers to the radius of the drone circling before the forced landing, and the second unit of remaining energy refers to the current unit of remaining energy of the target drone when it flies to the preset distance from the forced landing circling radius. The preset distance refers to the distance from the forced landing circling radius, which can be set according to the situation, such as 50 meters.

[0104] Specifically, since the target drone has sufficient remaining energy, it can circle around the forced landing point to consume energy before landing. However, when the target drone flies to the vicinity of the forced landing circling radius, some energy has been consumed, and the remaining energy needs to be evaluated again. Therefore, it is necessary to determine whether the second unit remaining energy of the target drone is greater than the unit boundary energy.

[0105] S306, if the second unit residual energy is less than or equal to the unit boundary energy, controlling the target UAV to continue to fly toward the forced landing point according to the first control strategy; and determining whether the first relative altitude of the target UAV is lower than the ideal altitude for parachute opening or whether the first waiting distance for flight of the target UAV is less than the recovery distance during the process in which the target UAV continues to fly toward the forced landing point;

[0106] In the specific implementation process, the first relative height refers to the relative height of the target UAV from the ground, and the ideal height for parachute opening refers to the required height for parachute opening; the first waiting flight distance refers to the remaining flight distance of the target UAV, and the recovery distance refers to the distance between the UAV and the forced landing point when the parachute is opened.

[0107] Specifically, judging whether the first relative height of the target UAV is lower than the ideal parachute opening height or whether the first waiting flight distance of the target UAV is less than the recovery distance is to judge whether the target UAV currently meets the parachute opening preparation conditions.

[0108] S308. If the first relative altitude is lower than the ideal altitude for parachute opening or the first distance to be flown is less than the recovery distance, the target UAV is controlled to fly toward the forced landing point according to the third control strategy; and when the second indicated airspeed is less than or equal to the allowable parachute opening speed threshold, the target UAV is controlled according to the second control strategy to continue flying toward the forced landing point in the predetermined posture for the preset time, and then the target UAV is controlled to enter the parachute opening and recovery process.

[0109] In the specific implementation process, the first relative height is lower than the ideal parachute opening height or the first waiting distance is less than the recovery distance, indicating that the parachute opening preparation conditions are met. At this time, the airspeed of the target UAV needs to be controlled to finally meet the parachute opening conditions. At this time, the target UAV is controlled to fly to the forced landing point according to the third control strategy to control the indicated airspeed of the target UAV. Specifically, the third control strategy includes: controlling the longitudinal heading of the target UAV according to the altitude holding control mode, and controlling the lateral heading of the target UAV according to the track tracking mode.

[0110] As an implementation method, the altitude control mode can use the pitch angle as an inner loop to control and maintain the altitude. Its input signals include the altitude command and the current altitude, ascent and descent rate, ascent and descent acceleration, pitch angle, pitch angle rate, angle of attack, etc. The output is the elevator deflection angle. The specific expressions include:

[0111]

[0112]

[0113] θ g =θ ref +θ NAV

[0114]

[0115]

[0116] Among them, δ e is the equivalent elevator deflection, q is the pitch rate, q g is the pitch rate, θ is the pitch angle, θ g is the pitch angle, θ ref is the pitch angle feedforward, H is the relative height of the UAV, is the lifting speed, H g is a given height, is the lifting speed given, is the gain of each controller in the control circuit of the height control mode.

[0117] Specifically, the main steps of implementing the altitude control mode include: ① receiving the altitude setting value (H) from the flight control computer; g ) ; ② Receive the height signal (H) from the sensor output; ③ and introduce the lifting speed The differential signal used as altitude control is used to enhance the system damping; ④ Combining the above signals, the pitch angle control target is output through the proportional integral differential controller, thereby achieving the altitude control of the target UAV.

[0118] As an alternative, see Figure 8 After the step of determining whether the second unit remaining energy of the target UAV is greater than the unit boundary energy when the target UAV is at a preset distance from the forced landing circling radius, the method further includes:

[0119] S312: If the second unit residual energy is greater than the unit boundary energy, controlling the target UAV to hover around the forced landing point according to the forced landing hovering radius according to the first control strategy;

[0120] In a specific implementation process, the second unit residual energy being greater than the unit boundary energy indicates that the current energy is still in excess and the parachute cannot be opened for forced landing. Therefore, the target UAV can be controlled to hover around the forced landing point according to the forced landing hovering radius; see Fig. 9 , Fig. 9 Schematic diagram of the target drone's forced landing route involving circling.

[0121] S314, continuously determining whether the third unit remaining energy of the target UAV is greater than the unit boundary energy during the hovering process;

[0122] In the specific implementation process, in order to finally achieve the forced landing with the parachute opened, it is necessary to continuously pay attention to whether the unit residual energy is less than the unit boundary energy during the circling process, so as to make subsequent preparations for the forced landing.

[0123] S316, if the third unit residual energy is less than or equal to the unit boundary energy, controlling the target UAV to continue to fly toward the forced landing point according to the first control strategy; and determining whether the second relative height of the target UAV is lower than the ideal parachute opening height or whether the second waiting flight distance of the target UAV is less than the recovery distance during the process of the target UAV continuing to fly toward the forced landing point;

[0124] In the specific implementation process, the second relative height is the relative height of the target UAV from the ground, the ideal height for parachute opening refers to the required height for parachute opening; the second waiting distance to fly refers to the remaining flight distance of the target UAV, and the recovery distance refers to the distance between the UAV and the forced landing point when the parachute is opened. Specifically, the execution process of this step is substantially the same as step S306, which will not be repeated here.

[0125] S318. If the second relative altitude is lower than the ideal altitude for parachute opening or the second distance to be flown is less than the recovery distance, the target UAV is controlled to fly toward the forced landing point according to the third control strategy; and when the third indicated airspeed is less than or equal to the allowable parachute opening speed threshold, the target UAV is controlled to continue flying toward the forced landing point in the predetermined posture for the preset time according to the second control strategy, and then the target UAV is controlled to enter the parachute opening and recovery process.

[0126] In the specific implementation process, the execution process of this step is substantially the same as step S308, and will not be repeated here.

[0127] It is understandable that circling around the forced landing circling radius to consume the remaining energy can, on the one hand, ensure the safety of energy consumption; on the other hand, the closer the distance to the forced landing point is, the easier it is to land at the forced landing point in an emergency, thus improving the accuracy of the forced landing.

[0128] In addition, the forced landing control method based on energy management in this embodiment actually calculates the indicated airspeed of the current aircraft, the relative height and distance from the forced landing point, and plans the trajectory in real time to make the aircraft fly stably to the forced landing point. Through the control circuits, specific expressions and control logic of each control mode in this embodiment, the residual energy control during the forced landing process is realized, and the target UAV is controlled to the maximum extent to accurately land at the designated location.

[0129] It should be understood that the above is only an example and does not constitute any limitation to the technical solution of the present application. Those skilled in the art can make settings based on needs in actual applications and no limitation is made here.

[0130] It is not difficult to find from the above description that the method of this embodiment provides a new method for forced landing of UAVs based on energy management. For UAVs that have lost power, real-time energy evaluation is performed on them, and based on the energy situation of the UAV, different control strategies are used to achieve smooth control of the forced landing of the UAV. The technical problem of unstable forced landing of UAVs in the prior art is solved, and the stability of the forced landing process of UAVs is improved; at the same time, based on the coordination of energy management and forced landing points, the forced landing control method can accurately control the forced landing point of the UAV and improve safety.

[0131] Reference Fig.10 Based on the same inventive concept, the embodiment of the present application also provides a UAV forced landing control device, including:

[0132] A first judgment module is used to judge whether the first unit residual energy of the target UAV is greater than the unit boundary energy when the target UAV loses power;

[0133] A first control module is configured to control the target UAV to fly toward the forced landing point according to a first control strategy if the first unit residual energy is less than or equal to the unit boundary energy; wherein the first control strategy includes: controlling the longitudinal heading of the target UAV according to a pitch angle airspeed control mode, and controlling the lateral heading of the target UAV according to a track tracking mode;

[0134] A second judgment module is used to judge whether the first indicated airspeed of the target UAV is less than or equal to the parachute opening speed threshold during the flight of the target UAV to the forced landing point;

[0135] The second control module is used to control the target UAV to continue flying to the forced landing point in a predetermined posture for a preset time according to a second control strategy if the first indicated airspeed is less than or equal to the allowable parachute opening speed threshold, and then control the target UAV to enter the parachute opening and recovery process; wherein the second control strategy includes: controlling the longitudinal heading of the target UAV according to the pitch angle control mode and the roll angle control mode; and controlling the lateral heading of the target UAV according to the track tracking mode.

[0136] It should be noted that each module in the UAV forced landing control device in this embodiment corresponds one-to-one to each step in the UAV forced landing control method in the aforementioned embodiment. Therefore, the specific implementation method and technical effects achieved by this embodiment can refer to the implementation method of the aforementioned UAV forced landing control method, which will not be repeated here.

[0137] It should be understood that the above is only an example and does not constitute any limitation to the technical solution of the present application. Those skilled in the art can make settings based on needs in actual applications and no limitation is made here.

[0138] In addition, in one embodiment, the present application also provides a control device, which includes a processor, a memory, and a computer program stored in the memory, and the computer program implements the steps of the method in the aforementioned embodiment when executed by the processor.

[0139] In addition, in one embodiment, the present application further provides a computer storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the method in the aforementioned embodiment are implemented.

[0140] In some embodiments, the computer readable storage medium may be a memory such as FRAM, ROM, PROM, EPROM, EEPROM, flash memory, magnetic surface memory, optical disk, or CD-ROM; or various devices including one or any combination of the above memories. The computer may be various computing devices including intelligent terminals and servers.

[0141] In some embodiments, executable instructions may be in the form of a program, software, software module, script or code, written in any form of programming language (including compiled or interpreted languages, or declarative or procedural languages), and may be deployed in any form, including as a stand-alone program or as a module, component, subroutine or other unit suitable for use in a computing environment.

[0142] As an example, executable instructions may, but need not, correspond to a file in a file system, may be stored as part of a file that stores other programs or data, such as in one or more scripts in a HyperText Markup Language (HTML) document, in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files storing one or more modules, subroutines, or code portions).

[0143] By way of example, executable instructions may be deployed to be executed on one computing device, or on multiple computing devices located at one site, or on multiple computing devices distributed across multiple sites and interconnected by a communication network.

[0144] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0145] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0146] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned implementation methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as a read-only memory / random access memory, a disk, or an optical disk), and includes a number of instructions for enabling a multimedia terminal device (which can be a mobile phone, a computer, a television receiver, or a network device, etc.) to execute the methods described in each embodiment of the present application.

[0147] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for controlling forced landing of a drone, characterized in that: include: When the target UAV loses power, determining whether the first unit remaining energy of the target UAV is greater than the unit boundary energy; The first unit of remaining energy refers to the first unit of remaining energy of the target UAV when it loses power; The unit boundary energy refers to the minimum energy that can support the target UAV to glide to the vicinity of the forced landing point; If the first unit residual energy is less than or equal to the unit boundary energy, the target UAV is controlled to fly to the forced landing point according to the first control strategy; wherein the first control strategy includes: controlling the longitudinal heading of the target UAV according to the pitch angle airspeed control mode, and controlling the lateral heading of the target UAV according to the track tracking mode; the pitch angle airspeed control mode is to control the airspeed by adjusting the pitch angle of the target UAV, and adopts a proportional plus integral control structure to control the airspeed at a given airspeed. To control the target, a proportional-integral control method is used to control the longitudinal loop; the lateral heading of the target UAV is controlled according to the track tracking mode, including the following steps: receiving a roll angle given value (φ) from the flight control computer; g ); receive the roll angle signal (p) and roll angular rate signal (p) from the sensor, and calculate the side offset distance (Y) and side deviation speed Based on the above signals, the proportional-integral controller is used to close the lateral and heading control loop, solve the control law and output the control signal to the actuator (aileron rudder) of the UAV system to achieve the track tracking control of the target UAV; the specific formulas involved include: f g =φ NAV in, and is the gain of each controller in the control circuit of the track tracking control mode; During the flight of the target UAV toward the forced landing point, determining whether the first indicated airspeed of the target UAV is less than or equal to a parachute opening speed threshold; If the first indicated airspeed is less than or equal to the allowable parachute opening speed threshold, the target UAV is controlled to continue flying towards the forced landing point in a predetermined posture for a preset time according to a second control strategy, and then the target UAV is controlled to enter a parachute opening and recovery process; wherein the second control strategy includes: controlling the longitudinal heading of the target UAV according to a pitch angle control mode and a roll angle control mode; and controlling the lateral heading of the target UAV according to the track tracking mode.

2. The method according to claim 1, characterized in that After the step of determining whether the first unit remaining energy of the target UAV is greater than the unit boundary energy, the method further includes: If the first unit residual energy is greater than the unit boundary energy, controlling the target UAV to fly toward the forced landing point according to the first control strategy; When the target UAV is at a preset distance from the forced landing circling radius, determining whether the second unit remaining energy of the target UAV is greater than the unit boundary energy; If the second unit residual energy is less than or equal to the unit boundary energy, the target UAV is controlled to continue to fly toward the forced landing point according to the first control strategy; and in the process of the target UAV continuing to fly toward the forced landing point, it is determined whether the first relative height of the target UAV is lower than the ideal parachute opening height or whether the first waiting flight distance of the target UAV is less than the recovery distance; If the first relative altitude is lower than the ideal altitude for parachute opening or the first distance to be flown is less than the recovery distance, the target UAV is controlled to fly to the forced landing point according to the third control strategy; and when the second indicated airspeed is less than or equal to the allowable parachute opening speed threshold, the target UAV is controlled to continue to fly to the forced landing point according to the predetermined attitude for the preset time according to the second control strategy, and then the target UAV is controlled to enter the parachute opening and recovery process; wherein the third control strategy includes: controlling the longitudinal heading of the target UAV according to the altitude control mode, and controlling the lateral heading of the target UAV according to the track tracking mode; The first relative height refers to the relative height of the target UAV from the ground, and the first waiting distance to fly refers to the remaining flight distance of the target UAV.

3. The method according to claim 2, characterized in that After the step of determining whether the second unit remaining energy of the target UAV is greater than the unit boundary energy when the target UAV is at a preset distance from the forced landing circling radius, the method further includes: If the second unit residual energy is greater than the unit boundary energy, controlling the target UAV to hover around the forced landing point according to the forced landing hovering radius according to the first control strategy; During the hovering process, continuously determining whether the third unit remaining energy of the target UAV is greater than the unit boundary energy; If the third unit residual energy is less than or equal to the unit boundary energy, the target UAV is controlled to continue to fly toward the forced landing point according to the first control strategy; and in the process of the target UAV continuing to fly toward the forced landing point, it is determined whether the second relative height of the target UAV is lower than the ideal parachute opening height or whether the second waiting flight distance of the target UAV is less than the recovery distance; If the second relative altitude is lower than the ideal altitude for parachute opening or the second distance to be flown is less than the recovery distance, the target UAV is controlled to fly toward the forced landing point according to the third control strategy; and when the third indicated airspeed is less than or equal to the allowable parachute opening speed threshold, the target UAV is controlled to continue flying toward the forced landing point in the predetermined posture for the preset time according to the second control strategy, and then the target UAV is controlled to enter the parachute opening and recovery process.

4. The method according to any one of claims 1 to 3, characterized in that The expression of the pitch angle airspeed control mode includes: i g =θ ref +θ NAV in, is the transfer function of the filter in the control circuit of the pitch angle airspeed control mode, s is a complex parameter, a is the parameter of the filter, δ e is the equivalent elevator deflection, q is the pitch rate, q g is the pitch rate, θ is the pitch angle, θ g is the pitch angle, θ ref is the pitch angle feedforward, θ NAV is the pitch angle calculated by the guidance law, is the indicated airspeed given, V IAS is the indicated airspeed, is the gain of each controller in the control circuit of the pitch angle airspeed control mode.

5. The method according to any one of claims 1 to 3, characterized in that The expression of the pitch angle control mode includes: Among them, δ e is the equivalent elevator deflection, θ g is the given value of the pitch angle, θ is the pitch angle, It is the gain of each controller in the control circuit of the pitch angle control mode.

6. The method according to any one of claims 1 to 3, characterized in that The expression of the roll angle control mode includes: Among them, δ a is the equivalent aileron deflection, φ g is the given value of the roll angle, φ is the roll angle, is the gain of each controller in the control circuit of the roll angle control mode.

7. The method according to claim 2 or 3, characterized in that: The expression of the height control mode includes: i g =θ ref +θ NAV Among them, δ e is the equivalent elevator deflection, q is the pitch rate, q g is the pitch rate, θ is the pitch angle, θ g is the pitch angle, θ ref is the pitch angle feedforward, H is the relative height of the UAV, is the lifting speed, H g is a given height, is the lifting speed given, is the gain of each controller in the control circuit of the height control mode.

8. A UAV forced landing control device, characterized in that: include: A first judgment module is used to judge whether the first unit residual energy of the target UAV is greater than the unit boundary energy when the target UAV loses power; The first unit of remaining energy refers to the first unit of remaining energy of the target UAV when it loses power; The unit boundary energy refers to the minimum energy that can support the target UAV to glide to the vicinity of the forced landing point; The first control module is used to control the target UAV to fly to the forced landing point according to the first control strategy if the first unit residual energy is less than or equal to the unit boundary energy; wherein the first control strategy includes: controlling the longitudinal heading of the target UAV according to the pitch angle airspeed control mode, and controlling the lateral heading of the target UAV according to the track tracking mode; the pitch angle airspeed control mode is to control the airspeed by adjusting the pitch angle of the target UAV, and adopts a proportional plus integral control structure to control the airspeed at a given airspeed. To control the target, a proportional-integral control method is used to control the longitudinal loop; the lateral heading of the target UAV is controlled according to the track tracking mode, including the following steps: receiving a roll angle given value (φ) from the flight control computer; g ); receive the roll angle signal (p) and roll angular rate signal (p) from the sensor, and calculate the side offset distance (Y) and side deviation speed Based on the above signals, the proportional-integral controller is used to close the lateral and heading control loop, solve the control law and output the control signal to the actuator (aileron rudder) of the UAV system to achieve the track tracking control of the target UAV; the specific formulas involved include: f g =φ NAV in, and is the gain of each controller in the control circuit of the track tracking control mode; A second judgment module is used to judge whether the first indicated airspeed of the target UAV is less than or equal to the parachute opening speed threshold during the flight of the target UAV to the forced landing point; The second control module is used to control the target UAV to continue flying to the forced landing point in a predetermined posture for a preset time according to a second control strategy if the first indicated airspeed is less than or equal to the allowable parachute opening speed threshold, and then control the target UAV to enter the parachute opening and recovery process; wherein the second control strategy includes: controlling the longitudinal heading of the target UAV according to the pitch angle control mode and the roll angle control mode; and controlling the lateral heading of the target UAV according to the track tracking mode.

9. A control device, characterized in that: The control device comprises a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the processor executes the computer program to implement the method according to any one of claims 1 to 7.

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