Automatic take-off control method for large fixed-wing unmanned aerial vehicle

Abstract

The invention discloses an automatic takeoff control method for a large fixed-wing unmanned aerial vehicle. The takeoff stage of the unmanned aerial vehicle is divided into a takeoff running stage, a takeoff obstacle crossing stage, a first takeoff climbing stage and a second takeoff climbing stage. In the takeoff taxiing stage, controlling the unmanned aerial vehicle to accelerate to a front wheel lifting speed, controlling the unmanned aerial vehicle to keep a target roll angle, and controlling a yaw angle and a lateral offset distance of the unmanned aerial vehicle to align to a runway center line; in the takeoff obstacle crossing stage, controlling the unmanned aerial vehicle to climb to an obstacle crossing height at a target pitch angle, and controlling the unmanned aerial vehicle to keep a target course angle; in the first take-off and climbing stage, the unmanned aerial vehicle is controlled to climb to a safe height at a target pitch angle, and the unmanned aerial vehicle is controlled to keep a target side offset distance and a track angle; in the second take-off and climbing stage, the unmanned aerial vehicle is controlled to keep the target speed, and meanwhile the unmanned aerial vehicle is controlled to keep the target side offset distance and track angle. Automatic takeoff of the unmanned aerial vehicle can be accurately controlled, and the robustness and safety of automatic takeoff of the unmanned aerial vehicle are greatly improved.

Description

Technical Field

[0001] The invention belongs to the field of unmanned aerial vehicle automatic driving and relates to an automatic take-off control method for a large fixed-wing unmanned aerial vehicle. Background Art

[0002] Drone automatic flight is an important direction for the development of drone technology. It uses advanced algorithms and sensors to achieve self-navigation, path planning, environmental perception and automatic obstacle avoidance. With its advantages of high precision, high efficiency and high safety, drone automatic flight technology has shown broad application prospects in many fields. With the continuous advancement and innovation of technology, drone automatic flight technology will inject new vitality into social and economic development.

[0003] A complete UAV flight process includes the take-off phase, the air cruising phase and the landing phase. Compared with the air cruising phase, the take-off and landing phases of UAVs are more complex and risky. Most practices have shown that although the take-off and landing time is shorter, the frequency of accidents in these two phases is much higher than that in the air cruising phase. For fixed-wing UAVs, automatic take-off refers to the entire process from the UAV's acceleration on the runway to take-off and climbing to a safe height. The difficulties reflected are complex processes, high control technology requirements, and high risks. There are many constraints that need to be considered in the entire process from taxiing to take-off, such as taking off to prevent the UAV from rubbing its tail, the take-off attitude cannot be too large to prevent stalling, and the take-off distance cannot be too long to reach the obstacle crossing height. In the past, no manned aircraft in service has adopted automatic take-off, and the automatic take-off adopted by UAVs is basically a simple aircraft vertical speed control method. This method is mostly suitable for small UAVs or mature models with a service time, and is not suitable for newly developed large UAVs. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a large fixed-wing UAV automatic take-off control method, which can accurately control the automatic take-off of the UAV and greatly improve the robustness and safety of the automatic take-off of the UAV.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A large fixed-wing UAV automatic takeoff control method includes the following processes: The UAV takeoff phase is divided into the takeoff roll phase, the takeoff obstacle clearance phase, the first takeoff climb phase and the second takeoff climb phase; During the takeoff roll phase, the UAV is controlled to accelerate to the front wheel lift speed, while the UAV is controlled to maintain the target roll angle, and the yaw angle and side offset of the UAV are controlled to align with the centerline of the runway; During the obstacle crossing phase of takeoff, the UAV is controlled to maintain the target pitch angle and climb to the obstacle crossing height, while the UAV is controlled to maintain the target heading angle; In the first stage of takeoff and climb, the UAV is controlled to maintain the target pitch angle and climb to a safe altitude, while the UAV is controlled to maintain the target side offset and track angle; In the second stage of takeoff and climb, the UAV is controlled to maintain the target speed, and at the same time, the UAV is controlled to maintain the target side deviation and track angle.

[0006] Preferably, the takeoff rolling stage is the stage when the UAV accelerates from stationary to rolling speed before the UAV lifts its wheels; the takeoff obstacle crossing stage is the stage when the UAV rolls from the wheel lifting speed to the obstacle crossing height of 15 meters from the ground; the first stage of takeoff climbing is the stage when the UAV climbs to a safe height of 200 meters; the second stage of takeoff climbing is the stage when the UAV climbs to the cruising altitude of the UAV.

[0007] Preferably, during the take-off and rolling phase, the speed, roll angle, yaw angle and side offset of the UAV are used as control target variables.

[0008] Further, the UAV is controlled to accelerate to a front wheel lifting speed of 155 km / h, while the UAV is controlled to maintain a target roll angle of 0°, and the yaw angle and side offset of the UAV are controlled to align with the center line of the runway.

[0009] Preferably, during the take-off obstacle crossing stage, the pitch angle and yaw angle of the UAV are used as control target variables.

[0010] Furthermore, the UAV is controlled to maintain a target pitch angle of 5.5° and climb to an obstacle clearance height of 15m. At the same time, the UAV is controlled to maintain a target heading angle of 325°. If the time from climbing from the wheel rotation to the obstacle clearance height exceeds the protection time threshold of 5s, the UAV will fade the target pitch angle to the first stage target pitch angle of takeoff and climb, and fade the target pitch angle at a fading rate of 2° / s.

[0011] Preferably, in the first stage of takeoff and climb, the pitch angle, track angle and lateral deviation of the UAV are used as control target variables.

[0012] Further, the UAV is controlled to maintain a target pitch angle of 7° and climb to a safe altitude of 200 m, while the UAV is controlled to maintain a target side offset of 0 m.

[0013] Preferably, in the second stage of takeoff and climb, the speed, track angle and lateral deviation of the UAV are used as target control variables.

[0014] Furthermore, the UAV is controlled to maintain a target speed of 180 km / h and climb to a cruising altitude of 300 m. At the same time, the UAV is controlled to maintain a target side offset of 0 m. If the climbing speed of the UAV is zero, the current target speed instruction minus 15 km / h and 165 km / h is taken as the new target speed for control, and the target speed instruction is faded according to 2 seconds.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention divides and defines different sub-stages of the take-off stage of the UAV, divides the complex tasks of the take-off stage of the UAV into independent sub-tasks, sorts out the target tasks, namely the target control variables, to be controlled in each sub-task, namely the flight stage, from the independent sub-tasks, and controls the automatic take-off of the UAV according to the target control variables of the different sub-stages of the take-off stage, thereby solving the problem that the automatic take-off of the UAV cannot be accurately controlled due to the complex tasks and many constraints in the take-off stage, and the uncertain aircraft parameters and environmental parameters of the newly developed UAV, thereby greatly improving the robustness and safety of the automatic take-off of the UAV. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a control flow chart of the automatic take-off control method of fixed-wing UAV.

[0017] Figure 2 This is a diagram showing the stages of automatic takeoff for fixed-wing UAVs.

[0018] Figure 3 It is the control block diagram of the takeoff and rolling phase of the automatic takeoff control method for fixed-wing UAV.

[0019] Figure 4 It is a control block diagram of the takeoff obstacle crossing phase of the automatic takeoff control method for fixed-wing UAV.

[0020] Figure 5 It is the control block diagram of the first stage of takeoff and climb of the automatic takeoff control method of fixed-wing UAV.

[0021] Figure 6 It is the control block diagram of the second stage of takeoff and climb of the automatic takeoff control method of fixed-wing UAV. DETAILED DESCRIPTION

[0022] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0023] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs. The terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. The term "and / or" used in this article includes any and all combinations of one or more related listed items. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0025] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0026] The present invention proposes an automatic take-off control method for a large fixed-wing UAV to solve the problem of improving the robustness and safety of automatic take-off under the conditions of multiple take-off constraints and uncertainty of UAV-related parameters and environmental parameters.

[0027] like Figure 1 As shown, the automatic take-off control method for a large fixed-wing UAV described in the present invention includes: dividing and defining different sub-stages of the take-off phase of the UAV; obtaining target control variables for different sub-stages of the take-off phase of the UAV; and controlling the automatic take-off of the UAV according to the target control variables for different sub-stages of the take-off phase.

[0028] like Figure 2 As shown, the take-off phase of the UAV is divided and defined as the take-off rolling phase, the take-off obstacle crossing phase, the first phase of take-off climbing, and the second phase of take-off climbing. The take-off rolling phase is defined as the phase from the UAV being stationary to the rolling acceleration to the UAV wheel-lifting speed VR; the take-off obstacle crossing phase is defined as the phase from the UAV rolling from the wheel-lifting speed to the obstacle-crossing height of 15 meters off the ground; the first phase of take-off climbing is defined as the phase when the UAV climbs to a safe height of 200 meters; the second phase of take-off climbing is defined as the phase when the UAV climbs to the cruising altitude of the UAV.

[0029] In the takeoff and rolling stage, the UAV speed, roll angle, yaw angle and lateral deviation are used as control target variables; in the takeoff and obstacle crossing stage, the UAV pitch angle and yaw angle are used as control target variables; in the first stage of takeoff and climbing, the UAV pitch angle, track angle and lateral deviation are used as control target variables; in the second stage of takeoff and climbing, the UAV speed, track angle and lateral deviation are used as target control variables.

[0030] like Figure 3-Figure 6 As shown, the UAV is controlled to automatically take off according to the target control variables of different sub-stages of the take-off stage, where K_I in the figure is the integral gain, K_P and K_Q are both proportional gains, including the following process: like Figure 3 As shown, during the takeoff roll phase, the UAV is controlled to accelerate to a front wheel lift speed VR, while the UAV is controlled to maintain a target roll angle, and the yaw angle and side offset of the UAV are controlled to align with the centerline of the runway.

[0031] Specifically: the roll angle after signal limiting is used as the negative feedback of the roll angle command. After passing through the proportional gain link, the roll angle rate is used as the negative feedback signal and passes through the signal limiting and proportional gain links to perform roll attitude control to ensure that the UAV always maintains the target roll of 0°.

[0032] The yaw angle after signal limiting is used as the negative feedback of the yaw angle command. After the signal limiting and proportional gain link, the lateral deviation change rate is used as the positive feedback. After the proportional gain and integral gain link, the yaw angle rate is used as the negative feedback. After the limiting and proportional gain link, the outputs of the above four links are summed up to perform rudder control to ensure that the yaw angle and lateral deviation of the UAV are aligned with the center line of the runway.

[0033] like Figure 4 As shown, during the obstacle crossing stage of takeoff, the UAV is controlled to maintain the target pitch angle and climb to the obstacle crossing height while controlling the UAV to maintain the target heading angle (along the extended line of the runway). If the climb from the wheel rotation to the obstacle crossing height exceeds the protection time threshold of 5 seconds, the target pitch angle command is converted to the target pitch angle command of the first stage of takeoff, and the target pitch angle is faded at a fade rate of 2° / s.

[0034] Specifically: when the obstacle clearance altitude is not reached, the switch is selected to select a pitch angle command of 5.5°; if the time from the rotation of the wheels to the obstacle clearance altitude exceeds the protection time threshold of 5 seconds, the switch is selected to select a pitch angle command of 7° for the first stage of climbing, and the target pitch angle is faded at a fade rate of 2° / s. The pitch angle after signal limiting is used as a negative feedback signal and then passes through the limiting link, proportional gain and integral gain link. The pitch angle rate is used as a negative feedback signal and passes through the limiting link and proportional gain link to be superimposed on the pitch angle path, thereby controlling the aircraft to fly according to the pitch angle command of 7° for the first stage of climbing.

[0035] The yaw angle rate after signal limiting and proportional gain is used as negative feedback and superimposed with the roll angle after signal limiting and proportional gain to perform rudder control.

[0036] The yaw angle rate after signal limiting is used as the negative feedback of the yaw angle command 325°. After signal limiting and proportional gain links, aileron control is performed.

[0037] like Figure 5 As shown, in the first stage of takeoff climb, the UAV is controlled to maintain the target pitch angle and climb to a safe altitude, while the UAV is controlled to maintain the target side offset and track angle (along the extended line of the runway).

[0038] Specifically: the pitch angle after signal limiting is used as negative feedback of the pitch angle command of 7° in the first stage of climbing. After passing through the signal limiting and proportional gain links, the pitch angle rate after signal limiting is used as negative feedback to control the elevator and climb to a safe altitude.

[0039] The yaw angle rate after signal limiting and proportional gain is used as negative feedback and superimposed with the roll angle after signal limiting and proportional gain to perform rudder control.

[0040] The track angle after signal limiting is used as the negative feedback of the track angle command. After the signal limiting and proportional gain link, the lateral deviation change rate is used as the positive feedback. After the proportional and integral gain link, the outputs of the above two links are summed to perform aileron control to maintain the target lateral deviation and track angle.

[0041] like Figure 6 As shown, in the second stage of takeoff and climb, the UAV is controlled to maintain the target speed while controlling the UAV to maintain the target side deviation and track angle (along the extended runway). If the climbing speed of the UAV is zero, the current target speed instruction minus 15km / h is taken as the new target speed for control, and the target speed instruction is faded in 2 seconds.

[0042] Specifically: when the climb speed is greater than zero, the selection switch selects the second stage climb speed instruction of 180km / h; when the climb speed is zero, the selection switch selects the second stage climb speed instruction of 180km / h-15km / h; when the climb speed changes from greater than zero to zero, the climb speed passes through the attenuator and then passes through the selection switch as the second stage climb speed instruction; the airspeed after signal limiting is used as a negative feedback signal and then passes through the limiting link and the proportional gain and integral gain link; the pitch angle rate is used as a negative feedback signal and passes through the limiting link and the proportional gain link to be superimposed on the airspeed path, thereby controlling the aircraft to fly according to the second stage climb speed instruction.

[0043] The yaw angle rate after signal limiting and proportional gain is used as negative feedback and superimposed with the roll angle after signal limiting and proportional gain to perform rudder control.

[0044] The track angle after signal limiting is used as the negative feedback of the track angle command. After the signal limiting and proportional gain link, the lateral deviation change rate is used as the positive feedback. After the proportional and integral gain link, the outputs of the above two links are summed to perform aileron control to maintain the target lateral deviation and track angle.

[0045] The actual control method is The control process of the UAV takeoff and rolling phase is to control the UAV to accelerate to a front wheel lifting speed VR of 155km / h, while controlling the UAV to maintain a target roll angle of 0°, and controlling the UAV's yaw angle and side offset to align with the runway centerline.

[0046] The control process of the drone during the obstacle crossing phase of takeoff is to control the drone to maintain a target pitch angle of 5.5° and climb to an obstacle crossing height of 15m while controlling the drone to maintain a target heading angle of 325° (along the extended runway line). If the protection time threshold of 5s is exceeded from the wheel rotation to the obstacle crossing height, the drone will fade the target pitch angle to the first stage of takeoff climbing, and fade the target pitch angle at a fade rate of 2° / s.

[0047] The control process of the first stage of the UAV takeoff and climb is as follows: in the first stage of the takeoff and climb, the UAV is controlled to maintain a target pitch angle of 7° and climb to a safe altitude of 200m, while the UAV is controlled to maintain a target side offset of 0m (along the extended runway line).

[0048] The second stage control process of the drone takeoff and climb is as follows: in the second stage of takeoff and climb, the drone is controlled to maintain a target speed of 180km / h and climb to a cruising altitude of 300m, while the drone is controlled to maintain a target side offset of 0m (along the extended runway line). If the drone's climbing speed is zero, the current target speed command minus 15km / h and 165km / h is taken as the new target speed for control, and the target speed command is faded in 2 seconds.

[0049] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0050] In the above embodiments of the present application, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0051] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0052] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0053] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

[0054] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this patent should not be determined with reference to the above description, but rather with reference to the preceding claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a waiver of such subject matter, nor should it be considered that the applicant has not considered such subject matter to be part of the disclosed inventive subject matter.

Claims

1. A large fixed-wing UAV automatic take-off control method, characterized in that: The process includes: The UAV takeoff phase is divided into the takeoff roll phase, the takeoff obstacle clearance phase, the first takeoff climb phase and the second takeoff climb phase; During the takeoff roll phase, the UAV is controlled to accelerate to the front wheel lift speed, while the UAV is controlled to maintain the target roll angle, and the yaw angle and side offset of the UAV are controlled to align with the centerline of the runway; During the obstacle crossing phase of takeoff, the UAV is controlled to maintain the target pitch angle and climb to the obstacle crossing height, while the UAV is controlled to maintain the target heading angle; In the first stage of takeoff and climb, the UAV is controlled to maintain the target pitch angle and climb to a safe altitude, while the UAV is controlled to maintain the target side offset and track angle; In the second stage of takeoff and climb, the UAV is controlled to maintain the target speed, and at the same time, the UAV is controlled to maintain the target side deviation and track angle.

2. The automatic take-off control method for a large fixed-wing UAV according to claim 1 is characterized in that: The takeoff roll phase is the phase when the UAV accelerates from stationary to rolling speed before reaching the wheel-lifting speed of the UAV; the takeoff obstacle clearance phase is the phase when the UAV rolls from the wheel-lifting speed to the obstacle clearance height of 15 meters from the ground; the first phase of takeoff climb is the phase when the UAV climbs to a safe height of 200 meters; the second phase of takeoff climb is the phase when the UAV climbs to the cruising altitude of the UAV.

3. The automatic take-off control method for a large fixed-wing UAV according to claim 1 is characterized in that: During the take-off and rolling phase, the speed, roll angle, yaw angle and side offset of the UAV are used as control target variables.

4. The automatic take-off control method for a large fixed-wing UAV according to claim 3 is characterized in that: The UAV is controlled to accelerate to a front wheel lifting speed of 155 km / h, and the UAV is controlled to maintain a target roll angle of 0°, and the yaw angle and side offset of the UAV are controlled to align with the center line of the runway.

5. The automatic take-off control method for a large fixed-wing UAV according to claim 1 is characterized in that: During the obstacle-crossing takeoff phase, the pitch angle and yaw angle of the UAV are used as control target variables.

6. The automatic take-off control method for a large fixed-wing UAV according to claim 5 is characterized in that: The UAV is controlled to maintain a target pitch angle of 5.5° and climb to an obstacle clearance height of 15m. At the same time, the UAV is controlled to maintain a target heading angle of 325°. If the time from the wheel rotation to the obstacle clearance height exceeds the protection time threshold of 5s, the UAV will fade the target pitch angle to the first stage target pitch angle of takeoff and climb, and fade the target pitch angle at a fade rate of 2° / s.

7. The automatic take-off control method for a large fixed-wing UAV according to claim 1 is characterized in that: In the first stage of takeoff and climb, the pitch angle, track angle and lateral deviation of the UAV are used as control target variables.

8. The automatic take-off control method for a large fixed-wing UAV according to claim 7, characterized in that: The UAV is controlled to maintain a target pitch angle of 7° and climb to a safe altitude of 200m, while the UAV is controlled to maintain a target side offset of 0m.

9. The automatic take-off control method for a large fixed-wing UAV according to claim 1, characterized in that: In the second stage of takeoff and climb, the speed, track angle and lateral deviation of the UAV are used as target control variables.

10. The automatic take-off control method for a large fixed-wing UAV according to claim 9, characterized in that: The UAV is controlled to maintain a target speed of 180 km / h and climb to a cruising altitude of 300 m. At the same time, the UAV is controlled to maintain a target side offset of 0 m. If the climbing speed of the UAV is zero, the current target speed instruction minus 15 km / h and 165 km / h is taken as the new target speed for control, and the target speed instruction is faded according to 2 seconds.

Images