Offshore unmanned aerial vehicle stable take-off control method based on wave crest posture alignment

Abstract

The present application relates to the technical field of unmanned aerial vehicle offshore take-off control, and particularly relates to a kind of offshore unmanned aerial vehicle stable take-off control method based on wave crest alignment.The present application method is adapted to offshore tiltable unmanned aerial vehicle with altitude perception module, positioning attitude module, flight controller, heading tilting power system;The unmanned aerial vehicle stable take-off control method comprises the following steps: S11, establish coordinate system, collect altitude data, and fit wave period;S12, perceive and collect wave characteristics, and solve wave peak wave direction;S13, tilting angle solution;S14, pre-take-off judgment.The technical scheme of the present application solves the problems in the prior art, such as inability to actively match wave direction, large attitude adjustment oscillation, high wave working condition take-off failure risk and the like.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle (UAV) takeoff control technology, and in particular to a stable takeoff control method for UAVs at sea based on wave crest attitude alignment. Background Technology

[0002] With the rapid development of the drone industry, drones are being used in increasingly diverse scenarios across various fields. They are also widely applied in unmanned maritime operations. Various types of drones, possessing specific functions such as vertical takeoff and landing, high-speed cruising, cross-medium operations, and water taxiing, are widely used in tasks such as marine inspection, hydrological monitoring, maritime search and rescue, and maritime transportation. Therefore, most maritime drones possess both maritime operation and takeoff / landing capabilities. The takeoff methods for drones at sea can generally be divided into two categories: one is takeoff by taxiing on the water surface, and the other is direct vertical takeoff. When the waves are large, taxiing takeoff is difficult, making vertical takeoff a better choice.

[0003] Sea waves are characterized by periodic undulations and directional propagation, with wave crests exhibiting a continuous linear distribution. Maritime drones (UAVs) utilize these wave motion characteristics for attitude pre-adjustment, reducing the lateral overturning moment and attitude disturbance impact exerted by the waves. When the drone's fuselage axis is parallel or nearly parallel to the longline of the wave crest, the wave undulations directly affect the left and right sides of the drone, causing significant roll, buoyancy imbalance, and tilting. This can easily lead to loss of attitude control during takeoff, water immersion, and crash failure, severely reducing the success rate of maritime takeoffs and operational safety.

[0004] Current technologies lack strategies for identifying and precisely tilting the aircraft to align with the direction of ocean waves, and also lack a systematic control method that couples wave direction and attitude, making it impossible to achieve adaptive pre-attitude adjustment takeoff based on wave conditions. Therefore, by utilizing the undulating characteristics of waves, the relative attitude of the UAV to the waves can be adjusted so that the fuselage's bow and tail axes are as perpendicular as possible to the long line of the wave crest and parallel to the direction of wave propagation. Furthermore, takeoff should be aligned with the wave crest and avoid the wave trough, thereby improving the stability and success rate of maritime UAV takeoff.

[0005] To address the problems existing in the above-mentioned technologies, it is essential to research and design a novel stable take-off control method for maritime unmanned aerial vehicles based on wave crest attitude alignment, thereby overcoming the problems existing in the current technologies. Summary of the Invention

[0006] To address the technical problems of existing technologies, such as the inability to actively match wave direction, large attitude adjustment oscillations, and high risk of takeoff failure in high-wave conditions, this invention provides a stable takeoff control method for maritime unmanned aerial vehicles (UAVs) based on wave crest attitude alignment. This invention is primarily adapted to tiltable maritime UAVs, and its onboard equipment includes a sensing module, a positioning module, a flight controller, and a power system. Through a complete process of wave period fitting, wave crest length line calculation, minimum path attitude tilting, and wave crest-timed takeoff, the fuselage axis is made perpendicular to the wave crest length line, eliminating lateral overturning moments and improving takeoff stability in complex sea conditions.

[0007] This invention proposes a takeoff strategy that aligns the aircraft's attitude with the long line of the wave crest. This strategy adjusts the fuselage attitude so that the fuselage axis is perpendicular to the long line of the wave crest, eliminating the overturning moment and roll caused by the lateral movement of the waves. It also employs the shortest path attitude adjustment method to avoid large-angle rolls.

[0008] The specific technical means of this invention are as follows: A stable takeoff control method for unmanned aerial vehicles (UAVs) is adapted to a marine tiltable UAV equipped with an elevation sensing module, a positioning and attitude module, a flight controller, and a heading tilting power system. Furthermore, the method for stable takeoff control of unmanned aerial vehicles includes the following steps: S11. Establish a coordinate system, collect elevation data, and fit the wave period. Using the aircraft's center of mass as the center O, establish a global geographic coordinate system OXYZ. The UAV collects a discrete sequence of elevation data along the Z-axis of the sea surface height, calculates the average elevation, and counts the number of zero-crossings and monotonicity transitions to determine if the wave period has been fully collected. If incomplete data is collected, a longer data set will be collected again. Using the collected data, fit the wave period T and locate the wave crest.

[0009] S12. Sensing and collecting wave characteristics, and calculating wave crest and direction; based on the known wave period T and the sea surface height corresponding to the wave crest of the previous period recorded in real time, predicting the arrival of the next wave crest, and when the wave crest arrives, collecting continuous frames of sea surface data at the same depth on both sides of the fuselage through the airborne sensing module, mapping them onto the coordinate system OXYZ, and then projecting them onto the plane OXY. Then, based on the data points, fitting the slope of the wave crest longline using the least squares method, and calculating the slope of the perpendicular line to the wave crest longline, and calculating its angle with the X-axis. Simultaneously calculate the angle between the drone's current fuselage axis and the X-axis. .

[0010] S13. Tilting angle calculation; based on the known angle between the perpendicular line from the wave crest length and the X-axis. The angle between the current fuselage axis and the X-axis of the drone. Calculate the angle difference Given an angle based on experience. ,like If the drone is roughly perpendicular to the long line of the wave crest, then tilting is not necessary. Otherwise, depending on the angle... and The size relationship; and the angle difference and Based on the relationship, determine the minimum tilt path of the drone and tilt it.

[0011] S14. Pre-flight assessment; after tilting is complete, perform a convergence assessment, and then repeat steps one, two, and three until the conditions are met. It also records the sea surface height range and time corresponding to the wave crest of the previous cycle. It predicts the wave crest time and sea surface height range for the next cycle. When the UAV's sensing module detects that the sea surface height meets the conditions, and the time is the wave crest time, and the UAV's orientation is perpendicular to the longline of the wave crest, thus meeting the takeoff conditions, adaptive takeoff can be performed.

[0012] Furthermore, in step S11, the coordinate system is established as a global geographic coordinate system OXYZ: the origin O of the coordinate system coincides with the center of mass of the aircraft, the north direction is the X-axis, the west direction is the Y-axis, and the Z-axis is perpendicular to the OX and OY axes and points vertically upward. The OZ axis, together with the OX and OY axes, forms a right-handed system.

[0013] Furthermore, in step S11, the elevation data collected is a discrete sequence of sea surface height along the Z-axis collected by the UAV. k=1,2,3…, each sample corresponds to a time step. , , … Then, the average elevation within the sampling interval is calculated to eliminate sea level baseline offset: In the formula, n is the total number of elevation sampling points that have been collected.

[0014] Furthermore, in step S11, the fitted wave period is calculated as a zero-mean fluctuation sequence, which serves as the waveform judgment benchmark: . This indicates that the water level is above the average sea level. This indicates the sea level is below mean. Zero-mean sequence statistics are performed, representing the number of times the reference level is crossed. From positive to negative / from negative to positive, crossing In terms of location, within the wave period of a single fitted sine function, the waveform will cross the mean sea level twice consecutively, i.e., the number of zero-crossing points. Record this moment. The two zero-crossing moments when the positive changes to the negative or the negative changes to the positive. and Then perform monotonic switching statistics. Indicates a rising waveform. This indicates a downward trend in the waveform. Within a single wave cycle fitted to a sine function, there will be two points of trend reversal: a peak and a trough, which represent the number of monotonicity switching points. ; Combine the two indicators to make a joint judgment and set the judgment logic: and If a complete cycle has been collected, it is determined that the sampling time has been completed; otherwise, a longer segment will continue to be sampled. Fitting a periodic function to its periodic time, each sampling will record the corresponding zero-crossing time. and The period for the first sampling calculation is: The period for the second sampling calculation is , No. The period for each sampling calculation is .cycle , This represents the total number of elevation sampling points that have been collected so far. Find the peak and collect data in real time. ,make If it appears consecutively During the upward phase, waves appear continuously. The wave is in its downward phase. It appears repeatedly. After that, if it occurs f times Then record Change from positive to negative for f times of for , … and time This shows the sea surface height and time corresponding to the wave crest, where f can be selected based on the actual sampling frequency and wave model.

[0015] Furthermore, the method for sensing and collecting wave characteristics and calculating wave crest and direction in step S12 is as follows: given the wave period T and the sea surface height corresponding to the wave crest of the previous period recorded in real time. and f times sea ​​level and time .Pick , … The minimum value in is The height range of the wave crest is [ , ].

[0016] The drone calculates the arrival time of the next cycle peak as follows: and sea level height is [ , At the moment the next wave peak arrives, the UAV uses its onboard sensing module to collect p consecutive frames of data at the same depth on both sides of the sea surface. Since the UAV is at the wave peak at this time, the collected data is more accurate. The data points are mapped onto the coordinate system OXYZ without changing their orientation, ignoring the influence of the Z-axis, and then projected onto the plane OXY to form p points: ( , ), ( , )...( , )...( , ).

[0017] The formula for fitting the wave crest length using the least squares method is as follows:

[0018] in , ; This represents the slope of the long line of the wave crest, calculated from the solution.

[0019] After fitting the wave crest length vector using the least squares method, the perpendicular vector perpendicular to the wave crest length is calculated.

[0020]

[0021]

[0022] The angle between the perpendicular line to the wave crest line and the X-axis, calculated in the final solution, has a range of values ​​of [...]. , ].

[0023] Simultaneously calculate the heading angle of the drone's current bow and tail axes. The heading angle, represented by the geographic heading of the drone, is collected in real time by the drone's positioning and attitude perception system, and its value range is [ ]. , ].

[0024] Furthermore, the method for calculating the tilt angle in step S13 is as follows: Given that the angle between the perpendicular line perpendicular to the wave crest line and the X-axis is... The angle between the current bow and tail axes of the drone and the X-axis, i.e., the heading angle, is... The ultimate goal is to align the fuselage's bow and stern axes with the vertical line of the wave crest, i.e., to tilt the fuselage so that... ; Angle determination is difficult to achieve in actual working conditions. Therefore, given an angle ,like If the wave crest line is roughly perpendicular to the fuselage's bow and stern axis, then tilting is not necessary. Otherwise, tilting is required. Minimum tilt angle selection: Operating Condition 1: , ; The fuselage rotates counterclockwise, that is, in a north-northwest direction, with a rotation value of ; Operating Condition 2: , ; The fuselage rotates clockwise, that is, in a direction north-northeast, with a rotation value of ; Operating Condition 3: , ; The fuselage rotates clockwise, that is, in a direction north-northeast, with a rotation value of ; Operating Condition 4: , ; The fuselage rotates counterclockwise, that is, in a north-northwest direction, with a rotation value of .

[0025] Furthermore, the method for determining the pre-takeoff condition in step S14 is as follows: after the tilt is completed, a convergence determination is performed, and then the calculations in steps one, two, and three are performed again until the condition is met. It also records the sea level height corresponding to the wave peak of the previous cycle. and time The predicted peak time for the next cycle is... and sea level height is [ , When the actual time of the drone is ,or Where b = 1, 2, 3, ..., and the sensing module detects the sea surface height as [ , At that time, the drone will take off adaptively.

[0026] Furthermore, the core control logic mechanism of the maritime UAV stable takeoff control method based on wave crest attitude alignment is as follows: by tilting the heading, the bow and tail axes of the UAV fuselage are aligned with the vertical line of the long line of the wave crest, and the fuselage is vertically aligned with the long line of the wave crest, eliminating the overturning moment exerted by the waves along the fuselage laterally and suppressing the rolling and swaying during takeoff; at the same time, the shortest path tilt condition avoids large-angle back-and-forth adjustments that cause fuselage attitude oscillations, improving takeoff stability under high wave conditions.

[0027] Furthermore, the control method can be applied to three types of equipment: unmanned aerial vehicles (UAVs) that take off and land on fixed floating platforms, UAVs that are equipped with take-off and landing platforms on unmanned surface vessels (USVs), and independent UAVs that take off and land vertically on water. Only the elevation sampling trigger logic needs to be adapted and adjusted, while the core steps of wave period fitting, wave peak calculation, heading tilt, and timing take-off remain unchanged.

[0028] Compared with the prior art, the present invention has the following advantages: 1. The stable take-off control method for maritime UAVs based on wave crest attitude alignment provided by this invention proposes for the first time a take-off strategy based on long-line attitude alignment of wave crests. By adjusting the attitude of the fuselage axis perpendicular to the long-line of the wave crest, the overturning moment caused by the lateral movement of the waves is eliminated, thereby reducing the problems of rollover and attitude loss of maritime UAVs during take-off. 2. The stable takeoff control method for marine UAVs based on wave crest attitude alignment provided by this invention adopts the shortest path attitude adjustment method to avoid large-angle tilt oscillations. The attitude alignment accuracy can be set according to the actual situation. It can be combined with the adaptive takeoff strategies of various UAVs to significantly improve takeoff stability and success rate under complex wave conditions.

[0029] In summary, the technical solution of this invention solves the problems of the prior art, such as the inability to actively match wave direction, large attitude adjustment oscillations, and high risk of takeoff failure under high wave conditions. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a basic flowchart of the present invention; Figure 2 This is a schematic diagram of the attitude of the marine unmanned aerial vehicle (UAV) of the present invention relative to the wave crest; Figure 3 This is a schematic diagram of the long-line fitting of the wave peak in this invention; Figure 4 This is a schematic diagram of the wave crest line and its perpendicular line in this invention; Figure 5 This is a schematic diagram of the minimum tilt path of the UAV under the working conditions of this invention; Figure 6 This is a schematic diagram of the minimum tilt path of the UAV under the second working condition of the present invention; Figure 7 This is a schematic diagram of the minimum tilt path of the UAV under working condition three of the present invention; Figure 8 This is a schematic diagram of the minimum tilt path of the UAV under working condition four of the present invention. Detailed Implementation

[0032] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0035] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0036] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0037] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0038] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0039] like Figure 1 As shown, the present invention provides a method for stable takeoff control of a maritime unmanned aerial vehicle based on wave crest attitude alignment, and its implementation steps are as follows: Step 1: Establish a coordinate system based on the drone's location for subsequent data fitting and orientation model building.

[0040] Step 2: The drone collects Z-axis elevation data, and based on the elevation data and changes, fits waves and calculates the period T.

[0041] Step 3: When the UAV is at the wave crest, the onboard sensing module collects continuous frame depth point data of the sea surface on both sides of the fuselage. The point data is mapped onto the coordinate system OXYZ without changing the orientation. The wave crest length line is fitted by the least squares method to find the slope on the coordinate system, and the angle between the perpendicular line of the wave crest length line and the X-axis, i.e., the true north axis, is calculated.

[0042] Step 4: The UAV calculates the angle between its bow and stern axes and the X-axis, i.e., the heading angle, and determines whether a tilt is needed. If a tilt is needed, the minimum tilt angle and tilt direction are calculated, and the tilt is performed. After tilting, steps 3 and 4 are repeated until the determination is that no tilt is needed. When no tilt is needed, the UAV senses its current position and takes off at the next wave crest.

[0043] The specific steps are as follows: Step 1: Establish a coordinate system, collect elevation data, and fit the wave period. like Figure 2 As shown, a global geographic coordinate system OXYZ is established: the origin O of the coordinate system coincides with the center of mass of the aircraft, the X-axis is due north, the Y-axis is due west, and the Z-axis is perpendicular to the OX and OY axes and points vertically upward. The OZ axis, together with the OX and OY axes, forms a right-handed system.

[0044] 1. A discrete sequence of sea surface height along the Z-axis is collected by a drone. k=1,2,3…, each sample corresponds to a time step. , , … .

[0045] 2. Calculate the average elevation within the sampling interval to eliminate sea level baseline offset: In the formula, n is the total number of elevation sampling points that have been collected.

[0046] 3. Calculate the zero-mean fluctuation sequence as a benchmark for waveform judgment: . This indicates that the water level is above the average sea level. This indicates that the water level is below the average sea level.

[0047] 4. Zero-crossing statistics, i.e., the number of times the reference surface is crossed. Zero-mean series. From positive to negative / from negative to positive, crossing The position. Within the wave period of a single fitted sine function, the waveform will cross the mean sea level twice consecutively, i.e., the number of zero-crossing points. Record this moment. The two zero-crossing moments when the positive changes to the negative or the negative changes to the positive. and .

[0048] 5. Monotonicity switching statistics. Indicates a rising waveform. This indicates a downward trend in the waveform. Within a single wave cycle fitted to a sine function, there will be two points of trend reversal: a peak and a trough, which represent the number of monotonicity switching points. .

[0049] 6. Combine the two indicators to make a joint judgment and set the judgment logic: and If a complete cycle has been collected, it is determined that the sampling time has been completed; otherwise, sampling will continue for a longer period of time.

[0050] 7. Fit a periodic function to its periodic time; each sampling will record the corresponding zero-crossing time. and The period for the first sampling calculation is: The period for the second sampling calculation is , No. The period for each sampling calculation is .cycle , This represents the total number of elevation sampling points that have been collected so far.

[0051] 8. Locate wave peaks and collect data in real time. ,make If it appears consecutively During the upward phase, waves appear continuously. The wave is in its downward phase. It appears repeatedly. After that, if it occurs f times Then record Change from positive to negative for f times of for , … and time This represents the sea surface height and time corresponding to the wave crest, where f can be selected based on the actual sampling frequency and wave model.

[0052] Step 2: Sensing and collecting wave characteristics, and calculating wave crests and directions. The coordinate system still uses the global geographic coordinate system OXYZ, and the wave period T and the sea surface height corresponding to the wave crest of the previous period are known. and f times sea ​​level and time .Pick , … The minimum value in is The height range of the wave crest is [ , ].

[0053] 1. The drone calculates the arrival time of the next cycle peak as follows: and sea level height is [ , ].

[0054] 2. When the next wave peak arrives, the UAV uses its onboard sensing module to collect p consecutive frames of data at the same depth on both sides of the sea surface. At this time, the UAV is at the wave peak, resulting in more accurate data. The data points are mapped onto the OXYZ coordinate system without changing their orientation, ignoring the influence of the Z-axis, and then projected onto the OXY plane. For example... Figure 3 As shown, p points are formed: ( , ), ( , )...( , )...( , ).

[0055] 3. The formula for fitting the wave crest length using the least squares method:

[0056]

[0057]

[0058] in , ; This represents the slope of the long line of the wave crest, calculated from the solution. The angle between the perpendicular line to the wave crest line and the X-axis, calculated in the final solution, has a range of values ​​of [...]. , ].

[0059] like Figure 3 As shown, The wave crest length vector fitted by the least squares method, such as Figure 4 As shown, It is a perpendicular vector to the length of the wave crest.

[0060] Simultaneously calculate the heading angle of the drone's current bow and tail axes. The heading angle, represented by the geographic heading of the drone, is collected in real time by the drone's positioning and attitude perception system, and its value range is [ ]. , ].

[0061] Step 3: Tilting Angle Calculation The coordinate system still uses the geographic coordinate system OXYZ, such as Figure 5 As shown, and it is known that: a perpendicular line to the long line of the wave crest. The angle with the X-axis is The current axis of the drone's fuselage (both front and rear) The angle between the yaw angle and the X-axis is the heading angle. The ultimate goal is the fuselage's bow and stern axis. Perpendicular to the long line of the wave crest Overlap, that is, tilt the fuselage so that .

[0062] Angle determination is difficult to achieve in actual working conditions. Therefore, given an angle ,like If the wave crest line is basically perpendicular to the fuselage's bow and stern axis, then tilting is not required. Otherwise, tilting is necessary.

[0063] Minimum tilt angle selection: Operating Condition 1: , ; like Figure 5 As shown, the fuselage rotates counterclockwise, that is, in a direction of north-northwest, with a rotation value of .

[0064] Operating Condition 1: , ; like Figure 6 As shown, the fuselage rotates clockwise, specifically in a north-northeast direction, with a rotation value of [value missing]. .

[0065] Operating Condition 3: , ; like Figure 7 As shown, the fuselage rotates clockwise, specifically in a north-northeast direction, with a rotation value of [value missing]. .

[0066] Operating Condition 3: , ; like Figure 8 As shown, the fuselage rotates counterclockwise, that is, in a direction of north-northwest, with a rotation value of .

[0067] Step 4: Prepare for takeoff at the crest of the wave After the tilt is complete, a convergence check is performed, and steps one, two, and three are repeated until the condition is met. It also records the sea level height corresponding to the wave peak of the previous cycle. and time The predicted peak time for the next cycle is... and sea level height is [ , When the actual time of the drone is ,or Where b = 1, 2, 3, ..., and the sensing module detects the sea surface height as [ , At that time, the drone will take off adaptively.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for stable takeoff control of a maritime unmanned aerial vehicle based on wave crest attitude alignment, characterized in that: The aforementioned stable takeoff control method for UAVs is adapted to tiltable marine UAVs equipped with an elevation sensing module, a positioning attitude module, a flight controller, and a heading tilting power system. The aforementioned method for stable takeoff control of unmanned aerial vehicles includes the following steps: S11. Establish a coordinate system, collect elevation data, and fit the wave cycle; S12. Sensing and collecting wave characteristics, and calculating wave crests and directions; S13, Tilting angle calculation; S14. Pre-flight assessment.

2. The method for stable takeoff control of a maritime unmanned aerial vehicle based on wave crest attitude alignment according to claim 1, characterized in that: In step S11, the coordinate system is established as a global geographic coordinate system OXYZ: the origin O of the coordinate system coincides with the center of mass of the aircraft, the north direction is the X-axis, the west direction is the Y-axis, and the Z-axis is perpendicular to the OX and OY axes and points vertically upward. The OZ axis, together with the OX and OY axes, forms a right-handed system.

3. The method for stable takeoff control of a maritime unmanned aerial vehicle based on wave crest attitude alignment according to claim 1, characterized in that: In step S11, the elevation data collected is a discrete sequence of sea surface height along the Z-axis collected by the UAV. k=1,2,3…, each sample corresponds to a time step. , , … Then, the average elevation within the sampling interval is calculated to eliminate sea level baseline offset: In the formula, n is the total number of elevation sampling points that have been collected.

4. The method for stable takeoff control of a maritime unmanned aerial vehicle based on wave crest attitude alignment according to claim 1, characterized in that: In step S11, the fitted wave period is calculated as a zero-mean fluctuation sequence, which serves as the waveform judgment benchmark. , This indicates that the water level is above the average sea level. This indicates a value below mean sea level, and involves zero-point statistics, i.e., the number of times the reference level is crossed, resulting in a zero-mean sequence. From positive to negative / from negative to positive, crossing In terms of location, within the wave period of a single fitted sine function, the waveform will cross the mean sea level twice consecutively, i.e., the number of zero-crossing points. Record this moment The two zero-crossing moments when the positive changes to the negative or the negative changes to the positive. and Then perform monotonic switching statistics. Indicates a rising waveform. This indicates a downward trend in the waveform. Within a single wave cycle fitted to a sine function, there will be two points of trend reversal: a peak and a trough, which represent the number of monotonicity switching points. ; Combine the two indicators to make a joint judgment and set the judgment logic: and If a complete cycle has been collected, it is determined that the sampling time has been completed; otherwise, a longer segment will continue to be sampled. Fitting a periodic function to its periodic time, each sampling will record the corresponding zero-crossing time. and The period for the first sampling calculation is: The period for the second sampling calculation is , No. The period for each sampling calculation is ,cycle , This represents the total number of elevation sampling points that have been collected so far. Find the peak and collect data in real time. ,make If it appears consecutively During the upward phase, waves appear continuously. During the downward phase, waves appeared consecutively. After that, if it occurs f times Then record Change from positive to negative for f times of for ... and time This represents the sea surface height and time corresponding to the wave crest, where f can be selected based on the actual sampling frequency and wave model.

5. The method for stable takeoff control of a maritime unmanned aerial vehicle based on wave crest attitude alignment according to claim 1, characterized in that: The method for sensing and collecting wave features and calculating wave crests and directions in step S12 is as follows: Given the wave period T and the sea level height corresponding to the wave crest of the previous period (recorded in real time). and f times sea ​​level and time ,Pick , … The minimum value in is The height range of the wave crest is [ , ]; The drone calculates the arrival time of the next cycle peak as follows: and sea level height is [ , At the moment when the next wave peak arrives, the UAV uses its onboard sensing module to collect p consecutive frames of data at the same depth on both sides of the sea surface. At this time, the UAV is at the wave peak, and the collected data is more accurate. The point data is mapped onto the coordinate system OXYZ without changing its orientation, ignoring the influence of the Z-axis, and then projected onto the plane OXY to form p points: ( , ), ( , )...( , )...( , ); The formula for fitting the wave crest length using the least squares method is as follows: in , ; This represents the slope of the long line of the wave crest, calculated from the solution. After fitting the wave crest length vector using the least squares method, the perpendicular vector perpendicular to the wave crest length is calculated. The angle between the perpendicular line to the wave crest line and the X-axis, calculated in the final solution, has a range of values ​​of [...]. , ]; Simultaneously calculate the heading angle of the drone's current bow and tail axes. The heading angle, represented by the geographic heading of the drone, is collected in real time by the drone's positioning and attitude perception system, and its value range is [ ]. , ].

6. The method for stable takeoff control of a maritime unmanned aerial vehicle based on wave crest attitude alignment according to claim 1, characterized in that: The method for calculating the tilt angle in step S13 is as follows: Given that the angle between the perpendicular line to the long line of the wave crest and the X-axis is... The angle between the current bow and tail axes of the drone and the X-axis, i.e., the heading angle, is... The ultimate goal is to align the fuselage's bow and stern axes with the vertical line of the wave crest, i.e., to tilt the fuselage so that... ; Angle determination is difficult to achieve in actual working conditions. Therefore, given an angle ,like If the long line of the wave crest is basically perpendicular to the fuselage's bow and stern axis, then tilting is not necessary; otherwise, tilting is necessary. Minimum tilt angle selection: Operating Condition 1: , ; The fuselage rotates counterclockwise, that is, in a north-northwest direction, with a rotation value of ; Operating Condition 2: , ; The fuselage rotates clockwise, that is, in a direction north-northeast, with a rotation value of ; Operating Condition 3: , ; The fuselage rotates clockwise, that is, in a direction north-northeast, with a rotation value of ; Operating Condition 4: , ; The fuselage rotates counterclockwise, that is, in a north-northwest direction, with a rotation value of .

7. The method for stable takeoff control of a maritime unmanned aerial vehicle based on wave crest attitude alignment according to claim 1, characterized in that: The method for pre-flight judgment in step S14 is as follows: After the tilt is complete, a convergence check is performed, and steps one, two, and three are repeated until the condition is met. It also records the sea level height corresponding to the wave peak of the previous cycle. and time The predicted peak time for the next cycle is... and sea level height is [ , When the actual time of the drone is ,or Where b = 1, 2, 3, ..., and the sensing module detects the sea surface height as [ , At that time, the drone will take off adaptively.

8. The method for stable takeoff control of a maritime unmanned aerial vehicle based on wave crest attitude alignment according to claim 1, characterized in that: The core control logic mechanism of the maritime UAV stable takeoff control method based on wave crest attitude alignment is as follows: by tilting the heading, the bow and tail axes of the UAV fuselage are aligned with the vertical line of the long line of the wave crest, and the fuselage is vertically aligned with the long line of the wave crest, eliminating the overturning moment exerted by the waves along the fuselage laterally and suppressing roll and sway during takeoff; at the same time, the shortest path tilt condition avoids large-angle back-and-forth adjustments that cause fuselage attitude oscillation, improving takeoff stability under high wave conditions.

9. The method for stable takeoff control of a maritime unmanned aerial vehicle based on wave crest attitude alignment according to claim 1, characterized in that: The control method described can be applied to three types of equipment: unmanned aerial vehicles (UAVs) that take off and land on fixed floating platforms, UAVs that are equipped with take-off and landing platforms on unmanned surface vessels (USVs), and independent UAVs that take off and land vertically on water. Only the elevation sampling trigger logic needs to be adapted and adjusted, while the core steps of wave period fitting, wave peak calculation, heading tilt, and timing take-off remain unchanged.

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