A fixed-wing unmanned aerial vehicle unpowered precision landing autonomous navigation method
By gliding to the runway extension line after the engine of a fixed-wing UAV stops, and then circling and descending according to the circling radius, the glide ratio and roll angle are calculated in real time, which solves the problem of accurate landing of fixed-wing UAVs in the absence of power, and improves flight safety and landing accuracy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIAN AISHENG TECH GRP
- Filing Date
- 2023-07-21
- Publication Date
- 2026-08-04
AI Technical Summary
Existing fixed-wing UAVs struggle to achieve precise landings without power, especially when the landing area is dispersed or during long-distance, high-angle tracking routes, they are susceptible to wind shear, posing flight safety risks.
After the engine stops, the fixed-wing UAV glides to the runway extension line, hovers and descends according to the hovering radius, and calculates the glide ratio and roll angle in real time to ensure the change of the hovering radius on the last loop, thus achieving a precise landing.
It achieves precise landing in unpowered conditions, avoids multiple forced landings and large-angle maneuvers, enhances flight safety, reduces the impact of wind shear, and ensures the controllability of gliding mode and the accuracy of landing point.
Smart Images
Figure CN116859959B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of unpowered unmanned aerial vehicle (UAV) recovery technology, and relates to an autonomous navigation method for unpowered precision landing of fixed-wing UAVs. Background Technology
[0002] Currently, for fixed-wing UAVs with runway takeoff and landing (UTCs) experiencing engine failure and subsequent emergency landing, some UAVs employ a circular landing area concept, requiring a wide planned landing range and resulting in dispersed landing points, which is detrimental to precise landing. Other UAVs use a high-angle descent tracking path from the engine failure point, resulting in a long planned path that is susceptible to external interference such as wind shear during prolonged high-angle tracking, increasing flight safety risks. Still others employ figure-eight maneuvers or other methods to reduce speed and altitude during the return to the runway, resulting in excessive maneuvers that are also detrimental to flight safety. Therefore, this paper proposes a method for autonomous navigation for precise landing of unpowered fixed-wing UAVs that can maintain a low speed, meet flight quality requirements for landing attitude, and achieve a precise landing point after gliding landing in the absence of power. Summary of the Invention
[0003] Technical problems to be solved
[0004] To avoid the shortcomings of existing technologies, this invention proposes an autonomous navigation method for the precise, unpowered landing of fixed-wing UAVs, which can enable safer and more precise landings on the local runway in the event of an abnormal engine failure.
[0005] Technical solution
[0006] A method for autonomous navigation for precise unpowered landing of a fixed-wing unmanned aerial vehicle (UAV) is characterized by the following steps:
[0007] Step 1: During the flight of the fixed-wing UAV, after the engine stops during takeoff and landing, it glides from the engine stop point at a fixed safe speed and at a fixed glide angle to the airspace above the runway extension.
[0008] Step 2: Above the runway extension line, according to the hovering radius It performs a circling and descending flight, the process of which is as follows:
[0009] During the circling and descent flight, based on the rated safe speed and maintaining a fixed descent angle as per step 1, and according to the circling radius... Flight, wherein the roll angle of the UAV satisfies the maximum roll angle constraint. ;
[0010] Step 3: When descending to the glide ratio decision altitude At that time, record the change in height for a complete lap. :
[0011] The decision altitude for calculating the radius change of the last circle of the drone's hovering descent is: :
[0012]
[0013] Among them: the final glide height at the heading entry point equal:
[0014]
[0015] in: The glide ratio of the drone before landing is given by L, which is the horizontal distance between the runway landing point and the heading entry point.
[0016] Step 4: When the drone passes the heading cut-in point altitude Below the radius change decision height At that time, the radius of the last lap is calculated online in real time. :
[0017]
[0018] The drone according to the changed radius Perform a final circling descent;
[0019] Step 5: The drone follows the changed radius. Perform the final circling and descent, descending to... Autonomous navigation enters the course entry point and tracks the terminal glide path;
[0020] Ultimately, a precise landing was achieved at the rated descent speed and with a safe landing attitude.
[0021] The height change over a complete circle ,in: , At the decision altitude, the drone first circled and descended, passing over the heading point on the runway extension. And the altitude at which the drone circled and descended to skim over the runway extension when it reached the point of approach.
[0022] The height , The change in altitude is obtained directly from the height sensor.
[0023] The glide ratio is based on the ratio of the circumference of one drone rotation to the altitude drop during rotation. Calculate the glide ratio of the drone before landing. .
[0024] The roll angle ,in, This is the tangential component of the rated safe speed.
[0025] Beneficial effects
[0026] This invention proposes an autonomous navigation method for the precise, unpowered landing of a fixed-wing unmanned aerial vehicle (UAV). After the engine of the UAV fails during flight, it glides to the airspace above the runway extension; based on the hovering radius... It performs a circling descent flight, descending to the glide ratio decision altitude. At the time of descent, the actual change in altitude over a complete lap, and the distance between the runway landing point and the heading cut-off point, are taken into account. By comparing the glide altitude at the approach point with the final glide height, we obtain the decision altitude for the final circle radius change during the UAV's gliding descent, and the radius of the final circle. The UAV performs its final gliding descent according to the final circle radius, enters the approach point, and tracks the final gliding path. Finally, it achieves a precise landing at the rated gliding speed and with a safe landing attitude.
[0027] Specific beneficial effects:
[0028] 1. For emergency scenarios involving unmanned aerial vehicles (UAVs) experiencing engine failure and powerless gliding, a precise autonomous navigation and control method for returning to home airspace is proposed. This eliminates the need for a circular landing zone, preventing multiple forced landings. From the engine failure point to the extended runway return line, there is no tracking path during the gliding process, avoiding the large angles and susceptibility to high-altitude wind shear associated with long routes. Furthermore, when tracking the runway line at the end of the heading cut, there is no need for large maneuvers such as figure-eight turns to eliminate unsuitable speed and altitude at the entry point, enhancing flight safety.
[0029] 2. When calculating the glide ratio of the UAV during a flight, factors such as wind speed and weather conditions before landing are taken into account. The calculation is not affected by wind interference, ensuring that the glide mode is observable and controllable, and achieving precise landing.
[0030] 3. During the gliding and circling process, the radius transformation program is calculated online in real time, eliminating the influence of different pilots' psychological qualities or operational skills and other uncontrollable human factors, thus realizing autonomous navigation and control.
[0031] 4. When the method enters the end-point navigation line tracking, the altitude and speed control accuracy is high, which ensures the accuracy of the final landing point and the safety of the ground contact in advance.
[0032] 5. A feasible autonomous navigation and landing method is proposed for emergency scenarios involving single-engine fixed-wing UAVs gliding without power due to engine failure. This method has broad application prospects in various industries. Attached Figure Description
[0033] Figure 1Side-view diagram of autonomous navigation for precise landing.
[0034] Figure 2 Top-down diagram of autonomous navigation for precise landing
[0035] Figure 3 Flowchart of the method of this invention Detailed Implementation
[0036] The present invention will now be further described in conjunction with the embodiments and accompanying drawings:
[0037] The process is as follows Figure 3 As shown, the specific implementation includes the following steps:
[0038] Step 1: After the engine stops during the flight of the fixed-wing UAV with take-off and landing, control the horizontal stabilizer elevators according to the rated safe speed, and glide from the engine stop point to the airspace above the runway extension line while maintaining a fixed glide angle.
[0039] Specifically: During the flight of a certain type of fixed-wing UAV, the engine stopped. The current stop altitude is 3000m. From the engine stop point, the UAV maintains a fixed glide angle of -3 degrees at the rated safe speed of 130km / h and glides to the airspace above the runway extension.
[0040] Step Two: As Figure 1 , Figure 2 As shown, above the runway extension line, at a given radius It performs a circling descent, maintaining a fixed descent angle while adhering to its rated safe speed. The tracking radius... During flight, the UAV's roll angle satisfies the maximum roll angle constraint. .
[0041] The roll angle size satisfies the following formula:
[0042]
[0043] in, This is the tangential component of the rated safe speed.
[0044] Specifically: above the runway extension line, according to the circling radius... It performs a circling and descending flight, the process of which is as follows:
[0045] During the circling and descent flight, based on the rated safe speed of 130 km / h and maintaining a fixed descent angle of -3 degrees from step one, according to the circling radius... Flight, wherein the roll angle of the UAV satisfies the maximum roll angle constraint. ;
[0046] Step 3: During the circling and descent process in Step 2, when the drone's flight altitude reaches the glide ratio decision altitude... At the time of descent, record the actual descent volume of a complete circle. .
[0047]
[0048] in, , After ensuring the drone's flight altitude meets the glide ratio decision altitude, the drone first hovers and descends, passing over the heading point on the runway extension line. The second time the drone circled and descended, skimming over the runway extension and its heading point. The altitude at that time. This altitude change was obtained directly from the altitude sensor, and the wind conditions before the glide landing were taken into account when acquiring the data.
[0049] If the drone's flight altitude does not meet the glide ratio decision altitude, the drone will follow the tracking radius in step two. Perform circling and descent until the conditions are met, then proceed to step three.
[0050] Specifically: when descending to the glide ratio decision height At that time, record the change in height for a complete lap. :
[0051] The decision altitude for calculating the radius change of the last circle of the drone's hovering descent is: :
[0052]
[0053] Among them: the final glide height at the heading entry point equal:
[0054]
[0055] in: For the drone's glide ratio before landing, This is the horizontal distance between the runway landing point and the heading cut-in point.
[0056] Step 4: Calculate the drone's glide ratio before actual landing based on the ratio of altitude drop during one circle to the circumference of one circle. Based on this glide ratio, determine the distance between the runway landing point and the heading cut-in point. End glide height at the heading entry point ,satisfy ;
[0057] Specifically: when the drone passes the altitude of the heading cut-in point Below the radius change decision height At that time, the radius of the last lap is calculated online in real time. :
[0058]
[0059] The drone according to the changed radius Perform a final circling descent;
[0060] Step 5: Obtain the actual circling descent height based on Steps 3 and 4. With the end of the glide height The decision altitude for calculating the radius change of the last rotation of the UAV is... ,satisfy ;
[0061] When the drone passes the heading cut-in point altitude The decision height for radius change is lower than that calculated in step five. At that time, the radius of the last lap is calculated online in real time. ,satisfy
[0062] The drone according to the changed radius Perform a final circling descent.
[0063] If the drone's flight altitude does not meet the radius change decision altitude, the drone will track the radius according to step two. Perform circling and descent until the conditions are met, then proceed to step six.
[0064] Following step six, which involves online real-time and precise calculation of the drone's final descent trajectory, the drone accurately descends to its final glide altitude and autonomously enters its heading entry point to track the final descent path. Finally, it achieves a precise landing at its rated descent speed and with a safe landing attitude.
[0065] Specifically, the drone is based on the changed radius. Perform the final circling and descent, descending to... Autonomous navigation enters the course entry point and tracks the terminal glide path;
[0066] Ultimately, a precise landing was achieved at the rated descent speed and with a safe landing attitude.
[0067] This invention proposes a precise autonomous navigation method for returning to the home airfield in emergency scenarios where the UAV engine fails and there is no power. This eliminates the need for a circular landing zone, preventing multiple forced landings. From the point of failure to the extended runway line of the return flight, there is no tracking path during the gliding process, avoiding the large angles and susceptibility to high-altitude wind shear associated with long flight paths. Furthermore, when tracking the runway line at the end of the flight path, there is no need for large maneuvers such as figure-eight turns to eliminate unsuitable speed and altitude at the entry point, enhancing flight safety. The gliding ratio calculation for the current flight takes into account factors such as wind speed and weather conditions before landing, ensuring that the gliding mode is observable and controllable, achieving precise landing. During the gliding and hovering process, the radius change program is calculated online in real time, eliminating the influence of uncontrollable human factors such as different pilot psychological qualities or operational skills, achieving autonomous navigation control. When entering the terminal navigation line tracking phase, this method exhibits high accuracy in altitude and speed control, ensuring the accuracy of the final landing point and the safety of the ground contact.
[0068] This invention proposes a more precise autonomous navigation landing method for scenarios involving engine failure and unpowered gliding landing of fixed-wing UAVs with runway takeoff and landing capabilities. It has broad prospects for industry applications.
Claims
1. A method for autonomous navigation for unpowered precision landing of a fixed-wing unmanned aerial vehicle, characterized in that... The steps are as follows: Step 1: During the flight of the fixed-wing UAV, after the engine stops during takeoff and landing, it glides from the engine stop point at a fixed safe speed and at a fixed glide angle to the airspace above the runway extension. Step 2: Above the runway extension line, according to the hovering radius It performs a circling and descending flight, the process of which is as follows: During the circling and descent flight, based on the rated safe speed and maintaining a fixed descent angle as per step 1, and according to the circling radius... Flight, wherein the roll angle of the UAV satisfies the maximum roll angle constraint. ; Step 3: When descending to the glide ratio decision altitude At that time, record the change in height for a complete lap. : The decision altitude for calculating the radius change of the last circle of the drone's hovering descent is: : Among them: the final glide height at the heading entry point equal: in: The glide ratio of the drone before landing is given by L, which is the horizontal distance between the runway landing point and the heading entry point. The glide ratio is based on the ratio of the circumference of one drone rotation to the altitude drop during rotation. Calculate the glide ratio of the drone before landing. ; Step 4: When the drone passes the heading cut-in point altitude Below the radius change decision height At that time, the radius of the last lap is calculated online in real time. : The drone according to the changed radius Perform a final circling descent; Step 5: The drone follows the changed radius. Perform the final circling and descent, descending to... Autonomous navigation enters the course entry point and tracks the terminal glide path; Ultimately, a precise landing was achieved at the rated descent speed and with a safe landing attitude.
2. The method for autonomous navigation and unpowered precision landing of a fixed-wing unmanned aerial vehicle according to claim 1, characterized in that: The height change over a complete circle ,in: , At the decision altitude, the drone first circled and descended, passing over the heading point on the runway extension. And the altitude at which the drone circled and descended to skim over the runway extension when it reached the point of approach.
3. The method for unpowered precision landing and autonomous navigation of a fixed-wing unmanned aerial vehicle according to claim 2, characterized in that: The height , The change in altitude is obtained directly from the height sensor.
4. The autonomous navigation method for unpowered precision landing of a fixed-wing unmanned aerial vehicle according to claim 1, characterized in that: The roll angle ,in, This is the tangential component of the rated safe speed.