Unmanned aerial vehicle attitude compensation control method and multi-rotor unmanned aerial vehicle

Abstract

The application provides a UAV attitude compensation control method and a multi-rotor UAV. The control method comprises the following steps: acquiring an actual attitude of the UAV, calculating a compensation angle between the actual attitude and a predetermined attitude of the UAV; selecting a working frequency of the antenna system according to the compensation angle; and measuring the distance and / or angle between the UAV and an obstacle at the working frequency. The UAV attitude compensation control method and the multi-rotor UAV provided by the application can compensate for the angle deviation caused by the inclination of the UAV, so that the main radiation direction of the antenna system is always directed to the front, and the front is always detected.

Description

Technical Field

[0001] This invention belongs to the field of unmanned aerial vehicle (UAV) technology, and more specifically, relates to a method for attitude compensation control of UAVs and a multi-rotor UAV. Background Technology

[0002] With the development of science and technology and the improvement of scientific and technological levels in my country, drones are being used more and more widely in various fields. In the drone industry, the complex environment causes many uncertainties in drone flight. To ensure safe flight, it is necessary to install automatic obstacle avoidance functions on drones, enabling them to brake autonomously when they sense they are too close to an obstacle. Because multi-rotor drones do not fly horizontally in one direction, we will take a quadcopter drone as an example (e.g., Figure 1 The four propellers, from bottom left to top right, are numbered 1, 2, 3, and 4. During the drone's forward flight, propellers 3 and 4 rotate at higher speeds than propellers 1 and 2. This causes the drone to fly at an angle, with the front lower than the rear (propellers 1 and 2 are lower; propellers 3 and 4 are higher). Figure 2 If the radar at the scanning angle is too low, it will scan downwards and not directly in front of the direction of flight. Also, when the drone is flying at a low altitude, it may mistake the ground for an obstacle, causing the drone to brake continuously. Summary of the Invention

[0003] The purpose of this invention is to provide a drone attitude compensation control method and a multi-rotor drone to solve the technical problem in the prior art that drones cannot scan the front when flying at an angle.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a method for attitude compensation control of a UAV, wherein the UAV includes an antenna system with frequency scanning capability, and the control method includes the following steps:

[0005] Obtain the actual attitude of the drone and calculate the compensation angle between the actual attitude and the predetermined attitude of the drone;

[0006] The operating frequency of the antenna system is selected based on the compensation angle.

[0007] At the operating frequency, the distance and / or angle between the drone and the obstacle are measured.

[0008] Optionally, the step of selecting the operating frequency of the antenna system based on the compensation angle includes:

[0009] The compensated radiation direction of the beam is obtained based on the compensation angle.

[0010] The operating frequency of the antenna system is determined based on the compensated radiation direction.

[0011] Wherein, when the UAV is in a predetermined attitude, the antenna system operates at a predetermined frequency and the corresponding radiation direction is the predetermined radiation direction, and the radiation direction of the beam of the antenna system at other operating frequencies is the compensation radiation direction.

[0012] Optionally, the angle between the compensated radiation direction and the predetermined radiation direction is equal to the compensated angle.

[0013] Optionally, the step of determining the operating frequency of the antenna system based on the compensated radiation direction includes:

[0014] Obtain a lookup table of the operating frequency and radiation direction of the antenna system;

[0015] The corresponding operating frequency is obtained from the lookup table based on the compensated radiation direction.

[0016] Optionally, the step of obtaining the actual attitude of the UAV and calculating the compensation angle between the actual attitude and the predetermined attitude of the UAV includes: detecting the pitch angle of the UAV according to the angular motion detector, wherein the pitch angle is the compensation angle.

[0017] Optionally, the step of measuring the distance between the drone and the obstacle at the operating frequency includes:

[0018] The transmitting antenna of the antenna system transmits a frequency-modulated continuous wave, which generates an echo signal after passing through an obstacle, and the receiving antenna of the antenna system receives the echo signal.

[0019] Calculate the distance between the drone and the obstacle.

[0020] The present invention also provides a multi-rotor unmanned aerial vehicle (UAV) using the above-described UAV attitude compensation control method. The multi-rotor UAV includes a UAV body and an antenna system fixed to the UAV body. The antenna system has frequency scanning capability and includes a transmitting antenna and a receiving antenna. The transmitting antenna includes a plurality of transmitting antenna arrays arranged in an array, and the receiving antenna includes a plurality of receiving antenna arrays arranged in an array.

[0021] Optionally, both the transmitting antenna array and the receiving antenna array include a series feed array.

[0022] Optionally, the string-fed array comprises a plurality of array elements connected in series, with the distance between adjacent array elements being half a wavelength.

[0023] Optionally, a bending structure is provided between two adjacent array elements.

[0024] The beneficial effects of the UAV attitude compensation control method and multi-rotor UAV provided by this invention are as follows: Compared with the prior art, the UAV attitude compensation control method of this invention first obtains the actual attitude of the UAV and calculates the compensation angle between the actual attitude and the predetermined attitude. After selecting the corresponding operating frequency of the antenna system according to the compensation angle, it finally measures the distance and / or angle between the UAV and the obstacle. When the UAV is flying diagonally downward, a suitable operating frequency can be selected according to its tilt angle, so that the main radiation direction of the antenna system is facing forward at this operating frequency. The distance and angle of the UAV relative to the obstacle are measured at this operating frequency, thereby compensating for the angle deviation caused by the UAV tilting, ensuring that the main radiation direction of the antenna system is always facing forward, and always detecting forward. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of a drone;

[0027] Figure 2 This is a schematic diagram of the scanning status when the drone is tilted.

[0028] Figure 3 This is a flowchart illustrating the UAV attitude compensation control method provided in an embodiment of the present invention.

[0029] Figure 4 A schematic diagram of the antenna system based on the phase difference angle measurement principle provided in an embodiment of the present invention;

[0030] Figure 5 This is a schematic diagram of the structure of a first antenna system provided in an embodiment of the present invention;

[0031] Figure 6 This is a schematic diagram of the structure of a second antenna system provided in an embodiment of the present invention.

[0032] The following are the labeling elements in the figure:

[0033] 10 - Transmitting antenna array; 11 - First feed array; 20 - Receiving antenna array; 21 - Second feed array. Detailed Implementation

[0034] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0035] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0036] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and 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. Therefore, they should not be construed as limitations on the present invention.

[0037] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0038] With the development of science and technology and the improvement of scientific and technological levels in my country, drones are being used more and more widely in various fields. In the drone industry, the complex environment causes many uncertainties in drone flight. To ensure safe flight, it is necessary to install automatic obstacle avoidance functions on drones, enabling them to brake autonomously when they sense they are too close to an obstacle. Because multi-rotor drones do not fly horizontally in one direction, we will take a quadcopter drone as an example (e.g., Figure 1 The four propellers, from bottom left to top right, are numbered 1, 2, 3, and 4. During the drone's forward flight, propellers 3 and 4 rotate at higher speeds than propellers 1 and 2. This causes the drone to fly at an angle, with the front lower than the rear (propellers 1 and 2 are lower; propellers 3 and 4 are higher). Figure 2If the radar at a certain angle scans downwards and cannot scan directly in front of the drone, it will fail to detect objects such as overhead power lines or birds directly in front of the drone, leading to a failure to brake in time. Furthermore, when the drone is flying at a low altitude, it may mistake the ground for an obstacle, causing it to brake continuously. To overcome these technical problems, this invention proposes a drone attitude compensation control method that ensures the drone's scanning area always faces directly forward, preventing failure to brake in time or accidental braking.

[0039] The attitude compensation control method for unmanned aerial vehicles (UAVs) provided in this embodiment of the invention will now be described. The UAV includes an antenna system with frequency scanning capability. The antenna system includes a transmitting antenna and a receiving antenna. The transmitting antenna transmits a detection signal. After encountering an obstacle, the detection signal is reflected to generate an echo signal. The receiving antenna receives the echo signal. The distance between the UAV and the obstacle is calculated based on the echo signal, and the angle of the UAV relative to the obstacle can also be calculated.

[0040] The transmitting antenna includes multiple transmitting antenna arrays 10, and the receiving antenna includes multiple receiving antenna arrays 20. Each element within the transmitting antenna array 10 operates at its resonant frequency, which corresponds to a radiation direction. The radiation directions corresponding to different resonant frequencies are at least partially different. Therefore, the beams generated by the antenna array formed by multiple elements at different resonant frequencies can correspond to different radiation directions, transmitting signals in different directions and receiving signals from different directions. Thus, an antenna whose radiation direction can change due to frequency variation can be called an antenna with frequency sweep capability.

[0041] Please see Figure 3 The UAV attitude compensation control method includes the following steps:

[0042] S10: Obtain the actual attitude of the UAV and calculate the compensation angle between the actual attitude and the UAV's predetermined attitude;

[0043] S20: Select the operating frequency of the antenna system based on the compensation angle;

[0044] S30: At the operating frequency, measure the distance and / or angle between the drone and an obstacle.

[0045] In step S10, the actual attitude is the actual attitude of the UAV during flight, and the predetermined attitude is the ideal attitude of the UAV at the current moment, which can also be understood as the attitude preset by the UAV at the current moment. During flight, the actual attitude of the UAV cannot always maintain consistency with the predetermined attitude, and there may be a certain deviation between the two. This will cause the main radiation direction of the antenna system in front of it to deviate, making it impossible to effectively detect obstacles in the predetermined direction. There is a certain deviation between the actual attitude and the predetermined attitude of the UAV, and the deviation between the two can be represented by an angle. In this invention, this angle is called the compensation angle.

[0046] In step S20, the operating frequency of the antenna system is selected based on the compensation angle. The compensation angle reflects the deviation between the actual attitude of the UAV and the predetermined attitude. Due to the change in the UAV's attitude, the attitude of the antenna system also changes accordingly, requiring the radiation direction of the antenna system to be adjusted to the radiation direction of the UAV in the predetermined attitude. Each radiation direction of the antenna system corresponds to a different operating frequency. Therefore, by determining the operating frequency of the antenna system based on the required compensation angle, and ensuring that the antenna system operates at this frequency, it can be guaranteed that its radiation direction does not deviate from the predetermined direction as the UAV's attitude changes.

[0047] In step S30, the distance and / or angle between the UAV and the obstacle is measured at the operating frequency. After determining the operating frequency of the antenna system according to step S20, the antenna system is made to operate at that operating frequency to measure the distance and / or angle between the UAV and the obstacle.

[0048] The UAV attitude compensation control method in the above embodiments first acquires the actual attitude of the UAV and calculates the compensation angle between the actual attitude and the predetermined attitude. After selecting the corresponding operating frequency of the antenna system based on the compensation angle, it finally measures the distance and / or angle between the UAV and the obstacle. When the UAV flies diagonally downwards, a suitable operating frequency can be selected based on its tilt angle, ensuring that the main radiation direction of the antenna system is directly forward at that frequency. The distance and angle measurement of the UAV relative to the obstacle is then performed at this operating frequency, thereby compensating for the angular deviation caused by the UAV's tilt and ensuring that the main radiation direction of the antenna system is always directly forward, thus always detecting the forward direction.

[0049] In some embodiments of the present invention, step S10 includes: detecting the pitch angle of the UAV based on an angular motion detector, wherein the pitch angle is a compensation angle. In a multi-rotor UAV, during forward flight, the rotational speed of the rear propeller is greater than that of the front propeller, causing the UAV to fly in an angled posture, i.e., lower in front and higher in back. Since the UAV needs to detect obstacles directly in front, in this state, the predetermined attitude of the UAV is that the front propeller and the rear propeller are at the same height, i.e., the UAV is horizontally positioned, and its pitch angle is 0 (the pitch angle is the angle between the UAV and the horizontal plane); the actual attitude of the UAV is at a compensation angle with the horizontal plane.

[0050] In this embodiment, the multi-rotor UAV includes an angular motion detector, which can be a gyroscope or similar structure. The angular motion detector can detect the angular velocity of at least one axis of rotation, that is, it can detect the attitude in at least one axis of rotation. For example, the angular motion detector can detect the attitude of at least the pitch axis.

[0051] In this embodiment, obtaining the actual attitude of the UAV includes obtaining the pitch angle of the UAV. The actual state of the UAV is horizontal, and the compensation angle between the actual attitude and the predetermined attitude is the pitch angle.

[0052] In other embodiments, obtaining the actual attitude of the UAV may also include obtaining the pitch angle, lead angle and roll angle of the UAV, with the compensation angle being the pitch angle.

[0053] In some embodiments of the present invention, step S20 includes:

[0054] S21: Obtain the compensated radiation direction of the beam based on the compensation angle;

[0055] S22: The operating frequency of the antenna system is determined based on the compensated radiation direction;

[0056] When the UAV is in a predetermined attitude, the antenna system operates at a predetermined frequency and the corresponding radiation direction is the predetermined radiation direction. The radiation direction of the beam corresponding to other operating frequencies of the antenna system is the compensated radiation direction.

[0057] After obtaining the compensation angle in step S20, the compensation radiation direction of the beam can be relatively determined, thus determining the operating frequency corresponding to the antenna's radiation direction as the compensation radiation direction. For ease of description and to avoid confusion, the radiation direction corresponding to the antenna system operating at a predetermined frequency when the UAV is in a predetermined attitude is called the predetermined radiation direction, and the radiation direction corresponding to the antenna system operating at other frequencies is called the compensation radiation direction. Both the predetermined radiation direction and the compensation radiation direction refer to the radiation direction corresponding to the antenna system at a certain operating frequency.

[0058] In some embodiments of the present invention, in step S21, the angle between the compensated radiation direction and the predetermined radiation direction is equal to the compensated angle; that is, the compensated radiation direction is the predetermined attitude of the UAV. For example, in the predetermined attitude of the UAV, the pitch angle of the UAV is 0, and the compensated radiation direction is the horizontal direction.

[0059] In some embodiments of the present invention, step S22 includes:

[0060] S221: Obtain the lookup table for the operating frequency and radiation direction of the antenna system;

[0061] S222: Obtain the corresponding operating frequency from the lookup table based on the direction of the compensated radiation.

[0062] In step S222, the operating frequency and radiation direction of the antenna system are set to correspond to each other. That is, one operating frequency band corresponds to one radiation direction range. In the lookup table, to facilitate the representation of the radiation direction range and for easy retrieval, the radiation direction range can be set as the range of angle differences relative to a predetermined radiation direction (i.e., the angle range in Table 1). In some embodiments, the angle interval corresponding to the compensation angle is searched in the lookup table, and then the frequency interval corresponding to the angle interval is searched. This frequency interval is the operating frequency of the antenna system obtained based on the compensation radiation direction. As shown in Table 1, the bandwidth of the antenna system is divided into N+1 intervals (N is a positive integer), that is, the frequency range of the antenna system is divided into N+1 frequency bands, each frequency band corresponding to an angle interval. This angle interval is relative to the predetermined radiation direction, which can be a horizontal direction. It should be noted that the bandwidth of the antenna system is not necessarily the sum of the bandwidths of the corresponding N+1 intervals.

[0063] In some embodiments, N is an even number, and the antenna system is divided into 0.5N+1 continuous intervals, which are called the first intervals. The second interval is formed between the midpoints of every two adjacent first intervals, and the number of second intervals is 0.5N. In this way, the bandwidth of the antenna system is divided into N+1 intervals, which makes the accuracy of the radiation direction intervals in the lookup table higher and the retrieved angle intervals more accurate.

[0064] In Table 1, F is the starting frequency of the antenna system, F+Δf is the ending frequency of the antenna system, and the angle interval is the interval corresponding to the angle with the horizontal plane. If the compensation angle is A, the angle interval corresponding to A is found in the lookup table (Table 1), and then the frequency interval corresponding to that angle interval is found. This frequency interval is the operating frequency of the antenna system mentioned above.

[0065] Table 1

[0066]

[0067]

[0068] In some embodiments of the present invention, step S30, measuring the distance between the drone and the obstacle at the operating frequency, includes:

[0069] The transmitting antenna of the antenna system transmits a frequency-modulated continuous wave, which generates an echo signal after passing through an obstacle, and the receiving antenna of the antenna system receives the echo signal.

[0070] Calculate the distance between the drone and the obstacle.

[0071] After obtaining the required operating frequency according to step S20, the wave transmitter is set to emit electromagnetic waves only within that operating frequency, thereby making the antenna system work only at that operating frequency, ensuring that its compensation radiation direction matches the predetermined attitude of the UAV, for example, ensuring that the compensation radiation direction always faces directly forward.

[0072] Distance between the drone and the obstacle f is the operating frequency, μ is the slope of the frequency-modulated continuous wave, and c is the speed of light.

[0073] In some embodiments of the present invention, in step S30, at the operating frequency, the angle between the UAV and the obstacle is measured. Specifically, the angle between the UAV and the obstacle can be measured using the phase method. The angle between the UAV and the obstacle is the echo angle of the echo signal.

[0074] In one embodiment of the present invention, please refer to Figure 4 The transmitting antenna includes multiple transmitting antenna arrays 10, one of which is the first transmitting antenna array 10; the receiving antenna includes multiple receiving antenna arrays 20, two of which are the first receiving antenna array 20 (RX1) and the second receiving antenna array 20 (RX2), and the line connecting the first receiving antenna array 20 and the second receiving antenna array 20 is a reference line.

[0075] The echo signal transmitted by the first transmitting antenna array 10 and reflected is received by the first receiving antenna array 20 and the second receiving antenna array 20, so as to measure the angle between the echo signal and the reference line.

[0076] Please see Figure 4 When the incident plane wave (echo signal) arrives at the first receiving antenna array 20 and the second receiving antenna array 20 at an incident angle θ, the tilt of the incident angle relative to the reference line results in a distance difference l when it reaches the two antennas. The relationship between this distance difference l and the angle θ is as follows:

[0077]

[0078] Assuming the first receiving antenna array 20 is the primary channel, meaning the intermediate frequency signal received by the first receiving antenna array 20 is described in the form of formula (1), then the intermediate frequency signals received by the first receiving antenna array 20 and the second receiving antenna array 20 can be described as follows:

[0079]

[0080]

[0081] Where Δτ is the time difference caused by the distance difference l, and obviously Δτ = 1 / c. Furthermore, for μ(τ + Δτ)t, since Δτ is very small relative to τ, its change in frequency is generally negligible. Therefore, we can approximate IF2(t) as:

[0082]

[0083] Assume that IF1(t) and IF2(t) have phase angles at frequency μτ, respectively. and So

[0084]

[0085] In this way, the angle θ between the received signal and the reference line can be obtained, and thus the arrival angle of the echo signal can be obtained.

[0086] This invention also provides a multi-rotor unmanned aerial vehicle (UAV). Using the UAV attitude compensation control method in any of the above embodiments, the multi-rotor UAV can ensure that the radiation direction of the antenna system always faces directly forward. Please refer to [link to relevant documentation]. Figure 5 A multi-rotor drone includes the drone body and an antenna system. The antenna system is fixed to the drone body, and its attitude changes in the same way as the drone body's attitude. The drone body may include a wave generator to make the antenna system operate at a corresponding frequency.

[0087] The antenna system has frequency scanning characteristics. The antenna system includes a transmitting antenna and a receiving antenna. The transmitting antenna transmits a detection signal. After the detection signal encounters an obstacle, it is reflected to generate an echo signal. The receiving antenna receives the echo signal. The distance between the UAV and the obstacle can be calculated based on the echo signal, and the angle of the UAV relative to the obstacle can also be calculated.

[0088] The transmitting antenna includes multiple transmitting antenna arrays 10, and the receiving antenna includes multiple receiving antenna arrays 20. Each element within the transmitting antenna array 10 operates at its resonant frequency, which corresponds to a radiation direction. The radiation directions corresponding to different resonant frequencies are at least partially different. Therefore, the beams generated by the antenna array formed by multiple elements at different resonant frequencies can correspond to different radiation directions, transmitting signals in different directions and receiving signals from different directions. Thus, an antenna whose radiation direction can change due to frequency variation can be called an antenna with frequency sweep capability.

[0089] The multi-rotor UAV provided by this invention, using the UAV attitude compensation control method in any of the above embodiments, first acquires the actual attitude of the UAV and calculates the compensation angle between the actual attitude and the predetermined attitude. After selecting the corresponding operating frequency of the antenna system based on the compensation angle, it finally measures the distance and / or angle between the UAV and the obstacle. When the UAV is flying diagonally downwards, a suitable operating frequency can be selected according to its tilt angle, so that the main radiation direction of the antenna system is facing forward at that operating frequency. The distance and angle of the UAV relative to the obstacle are measured at this operating frequency, thereby compensating for the angle deviation caused by the UAV tilting, ensuring that the main radiation direction of the antenna system is always facing forward, and always detecting forward.

[0090] In some embodiments of the present invention, please refer to Figure 5 Both the transmitting antenna array 10 and the receiving antenna array 20 include series-fed arrays. Each series-fed array includes multiple array elements connected in series. Specifically, adjacent array elements are electrically connected through structures such as microstrip lines, making the antenna array a series array. When feeding the series-fed array, there is a phase difference between adjacent array elements, so the radiation direction of the series-fed array can be adjusted by adjusting the operating frequency.

[0091] In some embodiments of the present invention, please refer to Figure 5 The transmitting antenna array 10 includes a plurality of first-string feed arrays 11 arranged sequentially at intervals. Figure 5 The first array (TX1, TX2, TX3, TX4) is arranged perpendicular to the length direction of the first feed array 11. Each first feed array 11 can be fed individually, or multiple first feed arrays 11 can be connected in parallel and then fed. When there are multiple first feed arrays 11, the radiation intensity of the transmitting antenna array 10 can be enhanced.

[0092] In some embodiments of the present invention, please refer to Figure 5 The receiving antenna array 20 includes multiple second-string feed arrays 21 arranged sequentially at intervals. Figure 5The second array (RX1, RX2, RX3, RX4) is arranged perpendicular to the length direction of the second array 21. Each second array 21 can be fed independently, or multiple second arrays 21 can be connected in parallel and then fed. When there are multiple second arrays 21, the signal reception capability of the receiving antenna array 20 can be improved.

[0093] In some embodiments of the present invention, please refer to Figure 6 The transmitting antenna array 10 includes seven first-string feed arrays 11, three of which are individually fed, and the other four are connected in parallel and then fed. The structure formed by the four first-string feed arrays 11 in parallel has higher gain and a narrower beamwidth, which can improve the target detection and tracking performance of the system. The receiving antenna array 20 includes four second-string feed arrays 21, which are individually fed.

[0094] In some embodiments of the present invention, please refer to Figure 5 and Figure 6 The distance between two adjacent array elements is half a wavelength, which is the wavelength corresponding to the operating frequency of the series-fed array. When the distance between two adjacent array elements is half a wavelength, the visible area is maximized and no grating lobes are generated.

[0095] In some embodiments of the present invention, the distance between two adjacent first feed arrays 11 is 'a', and the distance between two adjacent second feed arrays 21 is 'b'. The specific values ​​of 'a' and 'b' are not limited here. In some embodiments, 'a' can be four times 'b', which can improve the angular resolution in the horizontal direction.

[0096] In some embodiments of the present invention, a bent structure is provided between two adjacent array elements. The bent structure can be any non-linear structure, as long as it increases the electrical length between two adjacent array elements. Different multi-rotor UAVs often have different maximum flight angles during flight due to differences in structure, maximum flight speed, etc. Therefore, by providing a bent structure between two adjacent array elements, the electrical length between them can be extended, increasing the angle between the maximum compensation radiation direction and the horizontal direction, thus increasing the adjustable range of the antenna system's radiation angle and making it adaptable to a wider range of application scenarios.

[0097] Specifically, when the radar system operates in the frequency range of f0 to f BWhen f = f0 + B, where the initial frequency is f0 and the radar operating bandwidth is B. Assume that at the initial frequency f0, the length of each array element is 0.5λ0, the distance between the center points of two adjacent array elements is λ0, and the physical length of the feed line between two adjacent array elements is 0.5λ0 + 2Nλ0, where N is an integer; in common series-fed arrays, N is generally taken as 0. Here, λ0 = c / f0 is the wavelength corresponding to frequency f0, and c is the speed of light. That is, the wavenumber difference between the series-fed elements near frequency f0 is λ0 + 2Nλ0. Correspondingly, their phase difference is 0, i.e., equal-phase resonance. Therefore, the center of the main beam is along the normal to the plane of the array antenna, i.e., directly in front. And for the end of the radar's operating frequency range, i.e., f... B Nearby, the carrier wavelength changes to λ B =c / f B Correspondingly, its electric length changes as follows: After simplification, we can obtain: So, when N=0,

[0098] This explains why, in common series-fed arrays, when the frequency deviates from the center frequency, the main beam will deviate from the array normal direction, resulting in "upward" or "downward" deviation. If N > 0, this phenomenon will be even more pronounced, leading to a more significant frequency sweep phenomenon (physically represented as dispersion).

[0099] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for attitude compensation control of a UAV, the UAV including an antenna system with frequency scanning capability, characterized in that, Includes the following steps: Obtain the actual attitude of the drone and calculate the compensation angle between the actual attitude and the predetermined attitude of the drone; The operating frequency of the antenna system is selected based on the compensation angle. At the operating frequency, measure the distance and / or angle between the UAV and the obstacle; The step of selecting the operating frequency of the antenna system based on the compensation angle includes: The compensated radiation direction of the beam is obtained based on the compensation angle. The operating frequency of the antenna system is determined based on the compensated radiation direction. Wherein, when the UAV is in a predetermined attitude, the antenna system operates at a predetermined frequency and the corresponding radiation direction is the predetermined radiation direction, and the radiation direction of the beam of the antenna system at other operating frequencies is the compensated radiation direction; the angle between the compensated radiation direction and the predetermined radiation direction is equal to the compensation angle; The step of determining the operating frequency of the antenna system based on the compensated radiation direction includes: Obtain a lookup table of the operating frequency and radiation direction of the antenna system; The corresponding operating frequency is obtained from the lookup table based on the compensated radiation direction.

2. The UAV attitude compensation control method as described in claim 1, characterized in that, The step of obtaining the actual attitude of the UAV and calculating the compensation angle between the actual attitude and the predetermined attitude of the UAV includes: detecting the pitch angle of the UAV according to the angular motion detector, wherein the pitch angle is the compensation angle.

3. The UAV attitude compensation control method as described in claim 1, characterized in that, The step of measuring the distance between the drone and the obstacle at the operating frequency includes: The transmitting antenna of the antenna system transmits a frequency-modulated continuous wave, which generates an echo signal after passing through an obstacle, and the receiving antenna of the antenna system receives the echo signal. Calculate the distance between the drone and the obstacle.

4. A multi-rotor unmanned aerial vehicle (UAV) using the UAV attitude compensation control method according to any one of claims 1-3, characterized in that: The multi-rotor UAV includes a UAV body and an antenna system fixed to the UAV body. The antenna system has frequency scanning capability and includes a transmitting antenna and a receiving antenna. The transmitting antenna includes multiple transmitting antenna arrays arranged in an array, and the receiving antenna includes multiple receiving antenna arrays arranged in an array.

5. The multi-rotor UAV as described in claim 4, characterized in that, Both the transmitting antenna array and the receiving antenna array include series-feed arrays.

6. The multi-rotor UAV as described in claim 5, characterized in that, The string feed array comprises multiple array elements connected in series, with the distance between adjacent array elements being half a wavelength.

7. The multi-rotor UAV as described in claim 6, characterized in that, A bent structure is provided between two adjacent array elements.

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