Real-time trajectory planning method and system for steady-state rotation section after helicopter power failure

Abstract

The invention discloses a real-time trajectory planning method and system for a steady-state rotation section after power failure of a helicopter, and relates to the technical field of helicopter trajectory planning, and the method comprises the steps: initializing a system, and reading the current helicopter state information as an initial point; calculating a landing point reachable area; selecting a target landing point and a course angle as termination points; setting path parameters; planning a plane track, and dividing the path into a turning section S1, a straight line section L2 and a turning section S3; a vertical trajectory is solved, and a whole-course trajectory is obtained through linear interpolation and integration of the decline rate of the key node; judging an error, and if not, optimizing path parameters; and comparing the cost to select an optimal three-dimensional track, and updating in real time. According to the method, the calculation speed is greatly increased while the precision and reliability of the generated trajectory are ensured, so that real-time generation and updating of the trajectory under different working conditions are realized. By setting a cost function and a judgment criterion, preferential selection is carried out on the basis of ensuring existence of a feasible trajectory, and the quality of a landing trajectory is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of helicopter trajectory planning technology, and in particular to a real-time trajectory planning method and system for the steady-state rotation phase after helicopter power failure. Background Technology

[0002] Engine failure has long been a major cause of aviation accidents. Compared to fixed-wing aircraft, helicopters operate under more complex and harsher conditions, resulting in a higher rate of accidents. Autorotation descent is a special flight maneuver that utilizes airflow to drive the rotor and maintain its rotational speed. It is one of the main characteristics of rotorcraft and is the only safe landing method unique to helicopters after engine failure.

[0003] A typical autorotation descent process can be divided into the following stages in terms of time history: guided entry, steady-state autorotation, deceleration and leveling, landing, and touchdown taxiing. Among these, steady-state autorotation, as the stage with the longest span in both time and space, offers considerable planning space. Pilots typically use this stage to select a suitable landing site, appropriately and steadily change forward speed and descent rate, and maneuver the helicopter toward the target location, while simultaneously preparing for the subsequent near-landing phase.

[0004] The autorotation descent process involves numerous uncertainties. In practice, pilots often rely on their personal experience to maneuver the helicopter to a designated landing location, placing extremely high demands on their skills and resulting in a low success rate. If an onboard flight assistance system could take over the energy management and trajectory planning processes based on the current flight status, it would significantly reduce the pilot's workload and improve the landing success rate.

[0005] Currently, some universities and research institutions both domestically and internationally have conducted research on trajectory planning for the helicopter's autorotation descent phase, mainly focusing on solving the state and control variables during the descent process using optimal control methods. For example, patent CN119200661A discloses a safe trajectory planning method for helicopter autorotation landing. This method first determines the state and control variables based on a nonlinear autorotation dynamics model; then, it sets key objective functions and flight constraints to construct an autorotation landing optimization model; finally, from the perspective of optimal control, it uses the Gaussian pseudospectral method to solve the optimization model and obtain the autorotation landing trajectory. This method can generate accurate trajectories, but because it relies on the computationally complex optimal control solution, its computational cost is high and the solution time is long. It cannot well adapt to real-time human-machine interaction scenarios under engine failure conditions and has high hardware requirements, thus limiting its application in practical airborne applications. Therefore, there is an urgent need for a real-time trajectory planning method that ensures the accuracy and reliability of the trajectory generated during the helicopter's steady-state autorotation phase while significantly improving the computational speed to achieve real-time generation and updating of trajectories under different operating conditions. Summary of the Invention

[0006] In view of the problems of low solution efficiency and high hardware requirements of existing optimal control methods when the engine fails, this invention is proposed.

[0007] Therefore, the problem to be solved by the present invention is to provide a real-time trajectory planning method and system for the steady-state rotation phase after helicopter power failure.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, embodiments of the present invention provide a real-time trajectory planning method for the steady-state autorotation phase after helicopter power failure, comprising: initializing the system and reading the current helicopter state information as initial point state information; calculating the reachable landing zone based on the initial point state information, i.e., the maximum distribution area of ​​pre-landing points that can achieve a safe landing operation through the autorotation glide flight mode; the pilot or automatic system selecting a safe, obstacle-free target landing point and the desired landing heading angle within the displayed reachable zone, and setting it as the termination point state information in combination with the ideal entry speed and altitude of the near-ground landing phase; setting and assigning path parameters, wherein the path parameters represent the duration, acceleration, and yaw rate of the turning segment; planning a planar trajectory based on the initial and termination point state information and the path parameters, dividing the path into a turning segment S1, a straight segment L2, and a turning segment S3, and using a parameter optimization algorithm to ensure a safe landing. The system performs several steps: First, it checks the continuity of each plane trajectory. Second, it calculates the vertical trajectory corresponding to each plane trajectory, obtains the descent rate through the forward velocity and time nodes of four key nodes, and performs linear interpolation on the descent rate trajectory to obtain the trajectory of the entire descent rate change and the descent altitude trajectory. Third, it determines whether each vertical trajectory meets the requirements. If not, it returns to the above steps to correct the path parameters and replan the plane and vertical trajectories until the error requirements are met. Fourth, it compares the costs of all feasible paths after optimization, selects the path with the lowest cost as the final optimal three-dimensional glide trajectory, and outputs the optimal trajectory information to the flight control system or displays it on the pilot's cockpit display. Fifth, during the autorotation glide, the system periodically returns to the above steps to recalculate the initial point state information and the reachable area of ​​the landing point based on the deviation between the actual state of the helicopter and the planned trajectory, and updates the target landing point and path parameters to adapt to wind field changes, terrain uncertainties, and flight state deviations.

[0009] As a preferred embodiment of the real-time trajectory planning method for the steady-state rotation phase after helicopter power failure as described in this invention, the initial state information of the helicopter includes: current altitude, forward speed and acceleration, heading angle, rotor speed and descent rate; the heading angle is defined as the angle between the helicopter heading and due north in the north-east-ground coordinate system, with counterclockwise being positive.

[0010] As a preferred embodiment of the real-time trajectory planning method for the steady-state autorotation phase after helicopter power failure as described in this invention, the calculation of the landing point reachable area includes: based on the principle of optimal energy management, using the minimum descent rate that achieves the best glide performance in the quasi-steady-state trim data, calculating the farthest taxiing boundary that can achieve a safe landing through autorotation glide; considering control delay and various energy loss factors, under the premise that the change in heading angle of the helicopter during the glide does not exceed 180°, using the maximum descent rate in the quasi-steady-state trim data, calculating the nearest taxiing boundary, i.e., the inner boundary, that can achieve a safe landing; the area enclosed by the farthest taxiing boundary and the nearest taxiing boundary is the landing reachable area, which comprehensively considers terrain, wind field, and helicopter maneuverability constraints.

[0011] As a preferred embodiment of the real-time trajectory planning method for the steady-state rotation phase after helicopter power failure as described in this invention, the planned planar trajectory includes: selecting a target landing point within the landing reachable area, obtaining the coordinates of the starting point and the ending point and the heading angle constraints, considering helicopter maneuverability limitations, especially the minimum turning radius constraint determined by the maximum roll angle; proposing the concept of a path parameter set based on the geometric path planning method, dividing the helicopter motion process into three quasi-steady phases, namely turning segment S1, straight segment L2, and turning segment S3, wherein the two turning segments are used to realize the heading angle deflection process, and the straight segment is used to connect the two turning segments to ensure a smooth transition of the entire path and speed; the three trajectory segments are solved separately. The path parameter set includes the duration, acceleration, and yaw rate of the turning segment; for the turning segments S1 and S3, the acceleration and yaw rate are given by the parameter set, the forward velocity and heading angle are expressed as first-order linear functions of time, and the coordinates of the boundary points of the turning segment are calculated; the straight line segment L2 is the common tangent of the turning segments S1 and S3, and a parameter optimization algorithm is used to solve it to ensure that the trajectory meets the first-order continuity requirement.

[0012] As a preferred embodiment of the real-time trajectory planning method for the steady-state rotation phase after helicopter power failure as described in this invention, the method for solving the vertical trajectory corresponding to each planar trajectory includes: obtaining the descent rate corresponding to the four key nodes by substituting the forward flight velocity and time node of the four key nodes of the planar trajectory into the mapping relationship between the quasi-steady-state descent rate and the flight state; performing linear interpolation on the descent rate of the four key nodes to obtain the trajectory of the descent rate change throughout the entire process; and obtaining the descent altitude trajectory by numerical integration of the descent rate trajectory along the time axis.

[0013] As a preferred embodiment of the real-time trajectory planning method for the steady-state autorotation phase after helicopter power failure as described in this invention, the step of determining whether each vertical trajectory meets the requirements includes: defining the error of the vertical trajectory as the difference between the planned height and the actual integral height; if the error exceeds a preset threshold, returning to the path parameter setting step, the path parameters are corrected, or if the error exceeds the preset threshold, the path parameters are corrected and the cost is recalculated. The correction employs gradient descent algorithm for iterative optimization, including inputting initial parameters, learning rate, convergence threshold and maximum number of iterations, calculating the gradient of the cost function and updating the parameters until the convergence condition is met or the maximum number of iterations is reached. The constraints on the path parameters include the range of turn duration, acceleration range, and yaw rate range.

[0014] As a preferred embodiment of the real-time trajectory planning method for the steady-state rotation phase after helicopter power failure as described in this invention, the output optimal trajectory information includes a three-dimensional waypoint sequence, control reference quantities for each stage, and the predicted arrival time and remaining altitude at the target point.

[0015] Secondly, to further address the problems existing in helicopter trajectory planning, the present invention provides a real-time trajectory planning system for the steady-state rotation phase after helicopter power failure, comprising: The perception system includes a power failure monitoring module, a flight status acquisition module, and an environmental terrain perception module. These modules are used to collect real-time data on helicopter power failure status, key parameters during steady-state autorotation, and environmental obstacles and terrain data, providing basic data for subsequent planning. Data processing system: It has a built-in data cleaning module and a multi-source data fusion module to solve the problems of "noise, missing data and inconsistent format" in the perception layer data, generate standardized and highly reliable input data, and avoid trajectory planning deviations caused by erroneous data; The core planning system includes an reachability calculation module, a candidate landing point generation module, a planar trajectory planning module, and a 3D trajectory optimization module. Based on the preprocessed dataset and combined with the kinematic model of the helicopter's steady-state rotation segment, it generates a "safe, feasible, and optimal" landing trajectory in real time. Human-computer interaction system: It has a built-in system status and trajectory display module, which provides the pilot with real-time feedback on system status and trajectory information, while retaining the pilot's manual intervention authority.

[0016] Thirdly, embodiments of the present invention provide a computer device, including a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program is executed by the processor, it implements any step of the real-time trajectory planning method for the steady-state autorotation segment after helicopter power failure as described in the first aspect of the present invention.

[0017] Fourthly, embodiments of the present invention provide a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, it implements any step of the real-time trajectory planning method for the steady-state autorotation segment after helicopter power failure as described in the first aspect of the present invention.

[0018] The beneficial effects of this invention are as follows: 1. This invention adopts the quasi-steady-state assumption and flight mechanics trim to decouple three-dimensional motion into planar trajectory and vertical trajectory. This directly reduces the variable dimension and coupling calculation amount, resulting in the calculation time of the planning process being shortened from the second level of traditional methods to the millisecond level, thereby realizing real-time iterative updates and adapting to dynamic flight changes.

[0019] 2. This invention divides the trajectory into turning and straight segments by using the concept of a path parameter set. It combines geometric path planning and nonlinear optimization, such as gradient descent, to ensure that the trajectory meets first-order continuity and maneuver constraints. This not only guarantees the feasibility of the trajectory and its close fit to the pilot's actual operation, but also improves the trajectory quality and landing accuracy by minimizing the cost function of altitude error.

[0020] 3. This invention comprehensively considers energy loss, manipulation delay and environmental constraints to generate a landing reachable area, and supports human-machine interaction intervention, which further improves the robustness and safety of the system. Ultimately, while reducing the burden on the pilot, it raises the success rate of autorotation landing to a higher level, and is suitable for the actual deployment of airborne computer systems. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is the overall flowchart for steady-state glide trajectory planning in Example 1.

[0022] Figure 2 This is a simplified trajectory diagram used for calculating the maximum reachable area in Example 1.

[0023] Figure 3 This is a diagram illustrating the error definition of trajectory connection points based on geometric relationships in Example 1.

[0024] Figure 4 This is a system architecture diagram of the self-rotating glide trajectory planning system in Example 2. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0028] Example 1 Reference Figures 1 to 3 This is the first embodiment of the present invention, which provides a real-time trajectory planning method for the steady-state rotation phase after helicopter power failure, including the following steps: Step S0: Preparation phase. Establish a flight dynamics model after helicopter engine failure, considering changes in engine power and rotor speed. A quasi-steady-state assumption is introduced for the steady-state rotation phase. Based on this assumption, flight dynamics trimming yields the descent rate at specified forward velocity, acceleration, and rotor speed. This trimming result is then used to extend the horizontal motion, thereby decoupling the three-dimensional motion into a planar trajectory and a vertical trajectory.

[0029] Step S1: System Initialization and Input. Read the current helicopter status information and set it as the initial state, including current altitude, forward velocity and acceleration, heading angle, rotor speed, and descent rate. The heading angle is defined as the angle between the helicopter's heading and true north in the North-East-Earth coordinate system, with counter-clockwise being positive. Specifically, the initial state information is represented as follows: .

[0030] Step S2: Calculate the reachable landing area based on the initial state information, i.e., the maximum distribution area of ​​pre-landing points that can achieve a safe landing through the autorotation glide flight mode. This includes the following specific implementation steps: like Figure 2 As shown, to achieve gliding in different directions, the planar trajectory of the glide path is decomposed into a turning segment S0 that changes the heading angle and a straight gliding segment L0 after reaching the target heading angle. The method for calculating the boundary points of the glide path in any direction is as follows: ; In the formula, These are the coordinates of the end point of the turning segment, which is also the starting point of the straight segment. The coordinates of the boundary point of the reachable area can be found at the end point of the straight line segment. The time required to achieve a specified yaw angle is expressed as: ; In the formula, The maximum rate of change of yaw angle during the turning segment is affected by the helicopter's maneuverability boundary. The total time of the descent process is determined by the initial altitude and the rate of descent at each stage, and is expressed as: ; In the formula, The solution references the mapping relationship between the quasi-steady-state descent rate and the flight state.

[0031] By setting the heading angle to a range of 0~180°, the distribution of boundary points in different directions can be calculated. These boundary points together constitute the boundary of the maximum reachable area. By adjusting the heading angle change step size, the accuracy of the reachable area boundary can be changed.

[0032] Step S3: Select the target landing point. Within the displayed reachable area, the pilot or automated system, combining visual observation or sensor information (such as cameras and radar), selects a safe, unobstructed target landing point and the desired landing heading angle. This, along with the ideal entry speed and altitude settings for the near-landing phase, is used as the termination point status information, represented as: .

[0033] Step S4: Set and assign values ​​to the path parameters. The path parameters are represented as follows: .

[0034] Step S5: Based on the state information of the starting and ending points, and combined with the path parameters, plan the planar trajectory, including the following specific implementation steps: From a kinematic perspective, the path is divided into two main categories and three parts: straight segments and turning segments, namely turning segment S1, straight segment L2, and turning segment S3. To make the trajectory more closely resemble the motion characteristics of a helicopter, an acceleration variable is introduced to expand the feasible solution interval. Since the boundary constraints of the initial and final points are known, the trajectories S1 and S3 are calculated first, and the calculation method is as follows: ; For the two turning segments, the acceleration and yaw rate are given by the parameter set, and the forward velocity and heading angle are expressed as first-order linear functions of time: ; If the duration of the two turning segments Given that the coordinates of the remaining two boundary points of the turning segment can be represented as: ; The planned planar trajectory should meet the first-order continuity requirement, that is, there should be no abrupt change in velocity and heading angle. Therefore, the straight line segment L1 should be geometrically represented as the common tangent of the turning segments S1 and S3. The solution is obtained by using a parameter optimization algorithm.

[0035] like Figure 3 As shown, the definition is based on the duration of the turning segment. Cost function for independent variable: ; in, Let S1 be the line vector connecting the endpoint of S1 and the starting point of S2. They are respectively exist The projection of the direction, the physical meaning of the cost function is the relationship between the starting and ending velocities of the straight line segment and... The error is defined when When the required straight line segment trajectory is satisfied, the desired trajectory is achieved.

[0036] By combining S1, L2, and S3, the current path parameters can be obtained. The corresponding planar trajectory.

[0037] By changing the yaw direction of segments S1 and S3, up to four planar trajectories that meet the requirements can be obtained.

[0038] Step S6: Solve for the vertical trajectory corresponding to each planar trajectory, including the following specific implementation steps: The forward velocity of the four key nodes (the start and end points of each trajectory segment) can be obtained from the planar trajectory described in step 5. With three time points Substituting the mapping relationship described above, we can obtain the descent rates corresponding to the four key nodes. Linear interpolation of these four key nodes yields the trajectory of the overall rate of decline.

[0039] The descent altitude trajectory is obtained by integrating the descent rate trajectory over time t.

[0040] Step S7: Determine if each vertical trajectory meets the requirements. If yes, combine the planar trajectory and the vertical trajectory to obtain the three-dimensional trajectory; if not, return to step 4 to correct the path parameters, and re-trace the planar trajectory and the vertical trajectory until the error requirements are met. The specific implementation process is as follows: Define the error of the vertical trajectory: ; in, .

[0041] Define the constraints for the independent variables, i.e., the path parameters: ; in The derivation process is as follows: ; If the vertical error does not meet the accuracy requirements, return to step S4 and use gradient descent to correct the path parameters. Gradient descent is a classic iterative method for solving parameter optimization problems. Its core idea is to progressively update the parameters along the opposite direction of the gradient of the cost function until convergence to the optimal solution. Its core steps are as follows: A1: Input initial parameters Learning rate Convergence threshold Maximum number of iterations ; A2: Let the number of iterations be... Calculate the initial cost ; A3: Calculate the gradient ; A4: Update parameters ; A5: Calculate the new cost and determine if the convergence condition is met. The iteration terminates and the optimal parameters are output.

[0042] Not satisfied: If If k=k+1, recalculate; otherwise, terminate and display "not converged".

[0043] Step S8: Compare the costs of all feasible paths after optimization, and select the path with the lowest cost as the final optimal 3D glide trajectory. Output the optimal trajectory information, which is sent to the flight control system or displayed on the pilot's cockpit display, including: the 3D waypoint sequence, control reference values ​​for each stage, and the predicted time to reach the target point and remaining altitude.

[0044] Step S9: Real-time update. During the autorotation descent, the system can periodically re-execute steps 1-8 to replan the trajectory based on the deviation between the actual state of the helicopter and the planned trajectory, in order to adapt to dynamic changes.

[0045] In summary, this invention first collects the initial state information of the helicopter through system initialization, including data such as altitude, speed, and heading angle; then, it calculates the maximum reachable landing area based on a simplified trajectory model to determine the safe landing range; next, the pilot or system selects the target landing point and sets the path parameters; subsequently, the trajectory is decoupled into a planar part and a vertical part, where the planar part includes turning segments and straight segments, and continuity is ensured through geometric optimization, while the vertical part calculates the altitude trajectory through descent rate mapping and integration; the path parameters are iteratively optimized through error judgment and gradient descent algorithm until the accuracy requirements are met; finally, multiple feasible trajectories are compared, and the three-dimensional trajectory with the lowest cost is selected as the optimal path, supporting real-time updates to adapt to flight deviations, thereby achieving efficient and reliable airborne trajectory planning, significantly reducing computation time and improving landing success rate.

[0046] Example 2 This is the second embodiment of the present invention. Building upon Embodiment 1, this embodiment further provides a real-time trajectory planning system for the steady-state rotation phase after helicopter power failure. It uses a "data-driven - real-time calculation - safe execution" logic, highlighting the unique flight constraints and emergency scenario requirements of helicopters, and implementing functional requirements in a modular manner. For example... Figure 4 As shown, the system mainly includes: Power failure monitoring module: Real-time monitoring of engine speed, torque, fuel flow and other data to determine whether power failure has occurred and whether the engine has entered a steady-state rotation phase; Flight status acquisition module: integrates an inertial navigation system and a Beidou / GPS dual-mode positioning module to acquire flight data, including real-time altitude, ground speed, heading angle, attitude angle, three-axis acceleration and three-axis angular velocity, etc. Environment and terrain perception module: It uses devices such as lidar, weather radar, and visual cameras to detect obstacles and terrain around the flight path; Data cleaning module: Uses Kalman filtering algorithm to denoise sensor data, remove outliers, fill in missing data, and smooth fluctuating data, thereby improving the confidence of flight data; Multi-source data fusion module: It fuses position data from the inertial navigation system with BeiDou / GPS to improve the accuracy of altitude and heading angle; it fuses obstacle data from lidar with landing area images from visual cameras to confirm the authenticity of obstacles; Reachability calculation module: Reads flight data from sensors and navigation system, calculates using the method described in step 2, generates the farthest horizontal projection range that can be reached by autorotation glide under the current flight state and flight performance constraints, and updates it every 2 seconds; Candidate landing point generation module: Based on the reachable area under the current flight status and the perceived environmental terrain, the pilot or computer selects the best pre-landing point as the input to the downstream trajectory planning module; Planar trajectory planning module: Receives the start and end point coordinates, status data and path parameter information from upstream, generates a planar trajectory according to the method described in step 5 and passes it to the next module; 3D trajectory optimization module: Following the methods described in steps 6-8, the optimization process of path parameters and 3D trajectory is completed. When the defined error meets the set conditions, the autorotation glide trajectory under the constraints of the current flight state and the desired landing point is obtained.

[0047] System status and trajectory display module: Reads current status quantities, three-dimensional trajectory, control quantity guidance and other information, and displays them on the helicopter cockpit display screen.

[0048] This embodiment provides a computer device applicable to a real-time trajectory planning method for the steady-state rotation phase after helicopter power failure, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the real-time trajectory planning method for the steady-state rotation phase after helicopter power failure as proposed in the above embodiment.

[0049] The computer device can be a terminal, comprising a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0050] This embodiment also provides a storage medium storing a computer program. When executed by a processor, the program implements a real-time trajectory planning method for the steady-state rotation phase after helicopter power failure, as proposed in the above embodiment. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0051] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A real-time trajectory planning method for the steady-state rotation phase after helicopter power failure, characterized in that, include: Initialize the system and read the current helicopter status information as the initial point status information; The landing point reachable area is calculated based on the initial point state information, which is the maximum distribution area of ​​pre-landing points that can achieve safe landing operations through the autorotation glide flight mode. The pilot or automated system selects a safe, unobstructed target landing point and the desired landing heading angle within the displayed reachable area, and sets the ideal entry speed and altitude during the near-landing phase as the termination point status information. Set and assign values ​​to the path parameters, where the path parameters represent the duration, acceleration, and yaw rate of the turning segment; Based on the state information of the starting point and the ending point, and combined with the path parameters, a planar trajectory is planned, and the path is divided into turning segment S1, straight segment L2 and turning segment S3. A parameter optimization algorithm is used to ensure the first-order continuity requirement. The vertical trajectory corresponding to each planar trajectory is calculated. The descent rate is obtained by using the forward velocity and time nodes of four key nodes. The descent rate trajectory is linearly interpolated to obtain the trajectory of the descent rate change and the descent altitude trajectory throughout the entire process. Determine whether each vertical trajectory meets the requirements. If not, return to the above steps to correct the path parameters and replan the planar and vertical trajectories until the error requirements are met. Compare the costs of all feasible paths after optimization, select the path with the lowest cost as the final planned optimal three-dimensional glide trajectory, and output the optimal trajectory information to the flight control system or display it on the pilot's cockpit display. During the autorotation descent, the system periodically returns to the above steps to recalculate the initial point status information and the reachable area of ​​the landing point based on the deviation between the actual state of the helicopter and the planned trajectory, and updates the target landing point and path parameters to adapt to changes in wind field, terrain uncertainty and flight state deviation.

2. The real-time trajectory planning method for the steady-state rotation phase after helicopter power failure as described in claim 1, characterized in that, The initial state information of the helicopter includes its current altitude, forward speed and acceleration, heading angle, rotor speed, and descent rate; the heading angle is defined as the angle between the helicopter's heading and true north in the north-east-ground coordinate system, with counterclockwise being positive.

3. The real-time trajectory planning method for the steady-state rotation phase after helicopter power failure as described in claim 1, characterized in that, The calculation of the reachable landing zone includes: based on the principle of optimal energy management, using the minimum descent rate that achieves the best glide performance from the quasi-steady-state trim data, calculating the farthest taxiing boundary that can achieve a safe landing through autorotation glide; considering control delay and various energy loss factors, under the premise that the change in heading angle of the helicopter during the glide does not exceed 180°, using the maximum descent rate from the quasi-steady-state trim data, calculating the nearest taxiing boundary, i.e., the inner boundary, that can achieve a safe landing; the area enclosed by the farthest taxiing boundary and the nearest taxiing boundary is the reachable landing zone, which comprehensively considers terrain, wind field and helicopter maneuverability constraints.

4. The real-time trajectory planning method for the steady-state rotation phase after helicopter power failure as described in claim 1, characterized in that, The planned planar trajectory includes: selecting a target landing point within the landing reachable area, obtaining the coordinates of the start and end points and the heading angle constraints, considering helicopter maneuverability limitations, especially the minimum turning radius constraint determined by the maximum roll angle; proposing the concept of a path parameter set based on the geometric path planning method, dividing the helicopter motion process into three quasi-steady stages, namely turning segment S1, straight segment L2, and turning segment S3. The two turning segments are used to realize the heading angle deflection process, and the straight segment is used to connect the two turning segments to ensure a smooth transition of the entire path and speed. The three trajectory segments are solved separately. The path parameter set includes the duration, acceleration, and yaw rate of the turning segment; for the turning segments S1 and S3, the acceleration and yaw rate are given by the parameter set, the forward velocity and heading angle are expressed as first-order linear functions of time, and the coordinates of the boundary points of the turning segment are calculated; the straight line segment L2 is the common tangent of the turning segments S1 and S3, and a parameter optimization algorithm is used to solve it to ensure that the trajectory meets the first-order continuity requirement.

5. The real-time trajectory planning method for the steady-state rotation phase after helicopter power failure as described in claim 1, characterized in that, The calculation of the vertical trajectory corresponding to each planar trajectory includes: based on the forward velocity and time nodes of the four key nodes of the planar trajectory, substituting the mapping relationship between the quasi-steady-state descent rate and the flight state to obtain the descent rate corresponding to the four key nodes; performing linear interpolation on the descent rate of the four key nodes to obtain the trajectory of the descent rate change throughout the entire process; the descent altitude trajectory is obtained by numerical integration of the descent rate trajectory along the time axis.

6. The real-time trajectory planning method for the steady-state rotation phase after helicopter power failure as described in claim 1, characterized in that, The determination of whether each vertical trajectory meets the requirements includes: defining the error of the vertical trajectory as the difference between the planned height and the actual integrated height; if the error exceeds a preset threshold, returning to the path parameter setting step, the path parameters are corrected or if the error exceeds the preset threshold, the path parameters are corrected and the cost is recalculated. The correction employs gradient descent algorithm for iterative optimization, including inputting initial parameters, learning rate, convergence threshold and maximum number of iterations, calculating the gradient of the cost function and updating the parameters until the convergence condition is met or the maximum number of iterations is reached. The constraints on the path parameters include the range of turn duration, acceleration range, and yaw rate range.

7. The real-time trajectory planning method for the steady-state rotation phase after helicopter power failure as described in claim 1, characterized in that, The output optimal trajectory information includes a three-dimensional waypoint sequence, control reference values ​​for each stage, and the predicted arrival time and remaining altitude.

8. A real-time trajectory planning system for the steady-state rotation phase after helicopter power failure, based on the real-time trajectory planning method for the steady-state rotation phase after helicopter power failure as described in any one of claims 1 to 7, characterized in that, include: The perception system includes a power failure monitoring module, a flight status acquisition module, and an environmental terrain perception module. These modules are used to collect real-time data on helicopter power failure status, key parameters during steady-state autorotation, and environmental obstacles and terrain data, providing basic data for subsequent planning. Data processing system: It has a built-in data cleaning module and a multi-source data fusion module to solve the problems of "noise, missing data and inconsistent format" in the perception layer data, generate standardized and highly reliable input data, and avoid trajectory planning deviations caused by erroneous data; The core planning system includes an reachability calculation module, a candidate landing point generation module, a planar trajectory planning module, and a 3D trajectory optimization module. Based on the preprocessed dataset and combined with the kinematic model of the helicopter's steady-state rotation segment, it generates a "safe, feasible, and optimal" landing trajectory in real time. Human-computer interaction system: It has a built-in system status and trajectory display module, which provides the pilot with real-time feedback on system status and trajectory information, while retaining the pilot's manual intervention authority.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, it implements the steps of the real-time trajectory planning method for the steady-state autorotation segment after helicopter power failure as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements the steps of the real-time trajectory planning method for the steady-state autorotation segment after helicopter power failure as described in any one of claims 1 to 7.

Images