Wireless charging system of unmanned aerial vehicle and alignment wireless charging method thereof

Abstract

The invention discloses a wireless charging system of an unmanned aerial vehicle and an alignment wireless charging method thereof. A wireless charging coupling mechanism in the system comprises a primary coil on a charging pile and a secondary coil on the unmanned aerial vehicle; the unmanned aerial vehicle obtains position information through the GPS module; after the unmanned aerial vehicle lands to a certain height, image information is collected and transmitted to a computer for image processing, a specific landing marker of the charging pile is recognized, and the relative position of the unmanned aerial vehicle and the charging pile is calculated; the flight control system adjusts the flight pose of the unmanned aerial vehicle, feeds back flight data to the computer, controls the unmanned aerial vehicle to land on a landing platform of the charging pile, and sends a charging request instruction; and after receiving the instruction, the charging pile controls the positioning sliding table to drive the primary coil to move to be aligned with the secondary coil, so that charging is implemented. The problem that in the unmanned aerial vehicle recovery process, due to the fact that satellite signals are frequently disturbed, the calculation mode can affect the real-time performance of the unmanned aerial vehicle, the unmanned aerial vehicle cannot rapidly land when the electric quantity is low, and the unmanned aerial vehicle is exploded is solved.

Description

Technical Field

[0001] The present invention relates to the field of but not limited to the technical field of unmanned aerial vehicle (UAV) trajectory planning, and in particular to a wireless charging system for an unmanned aerial vehicle (UAV) and an aligned wireless charging method thereof. Background Art

[0002] With the development of drone technology, how to achieve fully automatic autonomous recovery or charging of drones has become a hot topic in current drone research.

[0003] At present, the fixed-point landing of drones mainly relies on the positioning signals of GPS or Beidou, but satellite signals are easily interfered by many factors such as the environment. For example, on rainy days or when blocked by high-rise buildings, the signal quality will deteriorate, and delays and drifts will occur. In addition, since the GPS positioning error is random and the positioning error is large, it is difficult to achieve precise landing by using GPS signals to guide the drone to land at a fixed point.

[0004] With the development of machine vision technology, many researchers have combined machine vision with drone positioning technology to improve the autonomous flight capabilities of drones, making drones smarter and making drone recovery more autonomous. During the drone recovery process, when the quality of the satellite positioning signal is good, the GPS positioning signal is used to guide the drone to return to flight in the first stage. When a landmark is detected during the flight, the image recognition technology is used in the second stage to identify specific ground patterns and estimate the relative position of the drone and the landmark. The flight control system adjusts the flight attitude and altitude based on this positional relationship, and visually guides the drone to land accurately on the take-off point landmark to complete the autonomous recovery and energy replenishment of the drone. However, satellite signals are often interfered with, and the use of complex landmarks or complex algorithms in visual calculations will affect the real-time performance of the drone; especially when the battery is low, it cannot land quickly, resulting in the risk of bombing. Summary of the invention

[0005] Purpose of the present invention: In order to solve the above technical problems, the embodiments of the present invention provide a wireless charging system for a drone and an aligned wireless charging method thereof, so as to solve the problem that during the recovery process of existing drones, satellite signals are often interfered with, and the existing visual computing method affects the real-time performance of the drone, resulting in the drone being unable to land quickly when the battery is low, resulting in the drone exploding.

[0006] Technical solution of the present invention: In a first aspect, an embodiment of the present invention provides a wireless charging system for a drone, comprising: a drone, a charging pile, and a wireless charging coupling mechanism; the wireless charging coupling mechanism comprises: a primary coil arranged on the charging pile, and a secondary coil arranged on the drone;

[0007] The drone includes: a computer, a camera, a flight control system, a GPS module, a visual positioning module and a secondary coil of a wireless charging coupling mechanism respectively connected to the computer, and a battery for supplying power to various electrical devices in the drone;

[0008] The GPS module is used to obtain the location information of the drone;

[0009] The computer is used to obtain the position information of the drone based on the GPS module. When the drone lands at a certain height, the camera is used to collect image information and transmit it to the visual positioning module inside the computer for image processing;

[0010] The visual positioning module is used to identify the specific landing marker of the charging pile through images and calculate the relative position of the drone and the charging pile;

[0011] The flight control system is used to control the flight of the drone to land on the landing platform of the charging pile by adjusting the flight posture of the drone and feeding back flight data to the computer according to the relative position of the drone and the charging pile, and to send a charging request instruction to the charging pile through information interaction between the computer and the flight control system;

[0012] The charging pile includes: a positioning slide, a primary coil of a coupling mechanism fixedly mounted on the positioning slide, a landing platform mounted above the positioning slide and the primary coil, and a microcontroller electrically connected to the primary coil of the positioning slide respectively;

[0013] The microcontroller is used to detect the position of the drone on the landing platform after receiving the charging request instruction, thereby controlling the positioning slide to drive the primary coil to move to align with the secondary coil on the drone, and controlling the primary coil to continuously send wirelessly transmitted electric energy, so that the secondary coil receives the wirelessly transmitted electric energy sent by the primary coil, thereby implementing charging.

[0014] Optionally, in the wireless charging system of the drone as described above,

[0015] The camera is fixedly installed under the drone, and a specific landing marker is pre-set on the landing platform of the charging pile;

[0016] The computer obtains the position information of the charging pile in the camera coordinate system based on the principle that the position of the drone in the camera coordinate system remains unchanged, thereby calculating the relative position of the drone and the charging pile.

[0017] Optionally, in the wireless charging system of the drone as described above,

[0018] The visual positioning module in the computer calculates the relative position of the drone and the charging pile in the following way:

[0019] According to the image information collected by the camera, the binary image is first extracted through the color value extraction algorithm, and the influence of noise is eliminated through opening and closing operations to obtain the contour of the binary image; the contour perimeter and area data of each binary image are obtained, and the circularity of each contour is calculated through the contour perimeter and area data of each binary image. The specific landing marker of the charging pile is screened out by comparing the circularity of each contour with the set threshold; the offset pixel position is calculated from the center of the contour of the identified binary image to the center of the camera's field of view as the relative pixel position of the drone and the charging pile.

[0020] Optionally, in the wireless charging system of the drone as described above,

[0021] The method of controlling the drone to land on the landing platform of the charging pile includes:

[0022] The computer controls the flight control system to adjust the position of the UAV according to the offset pixel position, and then vertically lands at a preset height (for example, 0.5 m) after reducing the offset pixel position calculated above, and repeats the operation of calculating the offset pixel position and vertically landing until the UAV lands on the landing platform of the charging pile; thereby, the microcontroller in the charging pile controls the movement of the movable slide so that the coil of the coupling mechanism is automatically aligned.

[0023] Optionally, in the wireless charging system of the drone as described above,

[0024] An infrared grating module is provided on the landing platform of the charging pile to identify multiple points and send coordinate information through the serial port to realize the positioning of the drone;

[0025] The positioning slide is configured as a dual-coordinate positioning slide, including: slide Y axes symmetrically arranged on both sides of the bottom of the landing platform, and slide X axes arranged between the two slide Y axes. The primary coil is arranged on the slide X axis through a coil bracket, and the position adjustment of the primary coil is controlled by the axial movement of the slide X axis itself and the movement of the slide X axis along the slide Y axis.

[0026] In a second aspect, an embodiment of the present invention further provides an alignment wireless charging method of a wireless charging system of an unmanned aerial vehicle, wherein the wireless charging method of aligning a wireless charging coupling mechanism is performed by using the wireless charging system of the unmanned aerial vehicle as described in any one of the above items, comprising:

[0027] Step 1: The drone reads its own power through the computer, and starts to return to charge when the power is lower than the set value. The computer navigates to the vicinity of the charging pile based on the drone location information obtained by the GPS module;

[0028] Step 2: Based on the location information of the drone obtained by the GPS module, the flight control system controls the drone to land at a preset height to ensure that the camera can capture the specific landing marker of the charging pile;

[0029] Step 3: Use the camera to collect image information, and the visual positioning module recognizes the specific landing marker of the charging pile through the image, and calculates the relative position of the drone and the charging pile in combination with the GPS module;

[0030] Step 4: The flight control system adjusts the flight posture of the drone according to the relative position of the drone and the charging pile, feeds back the flight data to the computer, controls the drone to land on the landing platform of the charging pile through information interaction between the computer and the flight control system, and sends a charging request instruction to the charging pile;

[0031] Step 5: After receiving the charging request instruction, the charging pile detects the position of the UAV on the landing platform through the microcontroller, thereby controlling the positioning slide to drive the primary coil to move to align with the secondary coil on the UAV, that is, to align the wireless charging coupling mechanism, thereby controlling the primary coil to continuously send wirelessly transmitted power, so that the secondary coil receives the wirelessly transmitted power sent by the primary coil, thereby implementing charging;

[0032] Step 6: After the charging pile is fully charged, the primary coil stops sending wirelessly transmitted power;

[0033] Step 7: After the drone is fully charged, it will fly away to perform other tasks.

[0034] Optionally, in the wireless charging method for aligning a wireless charging coupling mechanism of a drone as described above, before step 1, the method further includes:

[0035] A specific landing marker is formed on the landing platform of the charging pile, and the specific landing marker is a circular marker with a single color attached to the platform.

[0036] Optionally, in the alignment wireless charging method of the wireless charging coupling mechanism of the drone as described above, the method of calculating the relative position of the drone and the charging pile in step 3 includes:

[0037] Step 31, according to the image information collected by the camera, a binary image is first extracted by a color value extraction algorithm, and the influence of noise is eliminated by an opening and closing operation to obtain the outline of the binary image;

[0038] Step 32, obtaining the contour perimeter and area data of each binary image, calculating the circularity of each contour through the contour perimeter and area data of each binary image, and screening out the specific landing marker of the charging pile according to the comparison of the circularity of each contour with the set threshold;

[0039] In step 33, the offset pixel position is calculated from the center of the contour of the binary image to the center of the camera field of view, which is used as the relative pixel position of the drone and the charging pile.

[0040] Optionally, in the alignment wireless charging method of the wireless charging coupling mechanism of the drone as described above, the step 4 of controlling the drone to fly and land on the landing platform of the charging pile includes:

[0041] The flight control system is controlled to adjust the position of the drone according to the offset pixel position. After reducing the offset pixel position calculated in step 33, the drone vertically lands at a preset height, and steps 31 to 33 and the vertical landing operation of step 4 are repeated until the drone lands on the landing platform of the charging pile. The microcontroller in the charging pile controls the movement of the movable slide so that the coil of the coupling mechanism is automatically aligned.

[0042] Optionally, in the wireless charging method for aligning the wireless charging coupling mechanism of the drone as described above, the pixel position offset in step 33 includes:

[0043] The center of the image captured by the camera is recorded as the two-dimensional coordinate position of the drone, CenterPoint (cx, cy), and the contour center of the identified binary image is recorded as Target Point (tx, ty); the offsets of the offset pixel position of the drone in the x and y directions are:

[0044] Δx = cx - tx;

[0045] Δy=cy-ty.

[0046] Beneficial effects of the present invention: The embodiments of the present invention provide a wireless charging system for a drone and an aligned wireless charging method thereof, specifically a wireless charging method for aligning a wireless charging coupling mechanism in a drone based on visual multi-sensor fusion, which provides a wireless charging system and method for aligning a wireless charging coupling mechanism using a specific landing marker to guide the drone to land autonomously when the drone is low on power. In the specific implementation, firstly, navigation is performed to the vicinity of the charging pile through GPS data; secondly, the color of the specific landing marker is recognized by image recognition and contour information is extracted, the circularity of each contour is calculated to identify the logo pattern, and the relative position of the specific landing marker and the drone is calculated, and then the position of the drone is adjusted to land the drone on the charging pile, so that the drone can achieve "point-to-point" precise landing. In addition, the positioning slide of the charging pile can align the primary coil of the wireless charging coupling mechanism with the secondary coil of the drone, realize wireless charging, and ensure maximum efficiency of power transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0048] Figure 1 A schematic diagram of the overall structure of a wireless charging system for an unmanned aerial vehicle provided by an embodiment of the present invention;

[0049] Figure 2 A flow chart of a wireless charging method for aligning a wireless charging coupling mechanism using a wireless charging system for a drone provided by an embodiment of the present invention;

[0050] Figure 3 for Figure 1 A schematic diagram of a process of aligning a wireless charging coupling mechanism in a wireless charging system of a drone provided by the illustrated embodiment;

[0051] Figure 4 A schematic diagram of a specific landing marker selected in an embodiment of the present invention;

[0052] Figure 5 Schematic diagram of converting an image from RGB color space to HSV space in an embodiment of the present invention;

[0053] Figure 6 Schematic diagram of a specific landing marker extracted from a captured image according to the color range in Table 1 in an embodiment of the present invention;

[0054] Figure 7 A schematic diagram of the result of an image opening operation in an embodiment of the present invention;

[0055] Figure 8 is a schematic diagram of an image recognition result obtained by roundness screening in an embodiment of the present invention;

[0056] Fig. 9 A schematic diagram of the structure of a charging pile in a wireless charging system for a drone provided by an embodiment of the present invention; Fig. 9 Figure a shows the state of the drone before landing, and figure b shows the state of the drone after landing;

[0057] Fig.10 Schematic diagram of the automatic alignment procedure of the wireless charging coupling mechanism in an embodiment of the present invention. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical solution and advantages of the present invention more clear, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other arbitrarily without conflict.

[0059] As described in the above background technology, currently, machine vision has been combined with drone positioning technology to improve the autonomous flight capability of drones; however, during the recovery process of existing drones, satellite signals are often interfered with, and existing visual calculation methods affect the real-time performance of drones, resulting in the problem of failure to land quickly when the battery is low, leading to the explosion of the drone.

[0060] Specifically, with the continuous development of computer and artificial intelligence technology, drones are gradually entering people's lives, so the fixed-point landing of drones is worthy of in-depth study. Common fixed-point landing methods mainly include fixed-point landing based on GPS and fixed-point landing assisted by machine vision. In solution one, the use of GPS to achieve fixed-point landing of drones has a simple structure and low power consumption, but has high requirements for algorithms, and must be located with the help of satellites, which is easily interfered by external signals, and the positioning accuracy is not high, which has limitations. In solution two, a camera is installed on the drone to collect images, and the image is processed by the computer in the drone to obtain the azimuth information of the landing point. This solution has low cost, fast information acquisition speed and is not affected by the GPS signal strength; limited by the design requirements of the drone's size and weight, it can only use a small onboard computer with limited computing power. However, the existing machine vision-assisted solutions use complex landmarks or complex algorithms in visual computing, which will affect the real-time performance of the drone; especially when the battery is low, it cannot land quickly, resulting in the danger of bombing.

[0061] In view of the above problems, an embodiment of the present invention provides a wireless charging system for an unmanned aerial vehicle and an aligned wireless charging method thereof, specifically a wireless charging method for aligning a wireless charging coupling mechanism in an unmanned aerial vehicle based on visual multi-sensor fusion.

[0062] The present invention provides the following specific embodiments which can be combined with each other. The same or similar concepts or processes may not be described in detail in some embodiments.

[0063] Figure 1 The overall structure diagram of a wireless charging system for a drone provided by an embodiment of the present invention is shown in FIG. Figure 1 As shown, the main components of the wireless charging system for drones provided by the embodiment of the present invention include: drones, charging piles, and wireless charging coupling mechanisms. The wireless charging coupling mechanisms include: a primary coil arranged on the charging pile, and a secondary coil arranged on the drones.

[0064] like Figure 1 In the structure of the wireless charging system of the drone shown, the drone includes: a computer, a camera, a flight control system, a GPS module, a visual positioning module and a secondary coil of a wireless charging coupling mechanism respectively connected to the computer, and a battery for supplying power to various electrical devices in the drone.

[0065] The working process of the drone side in the embodiment of the present invention is as follows:

[0066] The battery is used to power various electrical devices in the drone; the GPS module is used to obtain the approximate location information of the drone; when the drone lands to a certain height, the computer uses a camera to collect image information and transmits it to its internal visual positioning module for image processing; the visual positioning module recognizes the specific landing markers of the charging pile through the image and calculates the relative position of the drone and the charging pile; the flight control system then controls the drone to land on the landing platform of the charging pile according to the relative position of the drone and the charging pile, and feeds back flight data to the computer, and through information exchange between the computer and the flight control system, controls the drone to fly and land on the landing platform of the charging pile, and sends a charging request instruction to the charging pile.

[0067] like Figure 1 In the structure of the wireless charging system of the drone shown, the charging pile includes: a positioning slide, a primary coil of a coupling mechanism fixedly mounted on the positioning slide, a landing platform mounted above the positioning slide and the primary coil, and a microcontroller electrically connected to the primary coil of the positioning slide respectively.

[0068] The working process of the charging pile side in the embodiment of the present invention is as follows:

[0069] The microcontroller receives the charging request instruction sent by the flight control system. First, after receiving the charging request instruction, the position of the UAV on the landing platform is detected, so as to control the positioning slide to drive the primary coil to move to align with the secondary coil on the UAV; secondly, when the primary coil is aligned with the secondary coil on the UAV, the wireless charging coupling mechanism can be used as a whole to realize wireless charging of the UAV battery. Specifically, the primary coil is controlled to continuously send wirelessly transmitted electric energy, so that the secondary coil receives the wirelessly transmitted electric energy sent by the primary coil, thereby implementing charging.

[0070] It should be noted that the use of a specific landing marker in the embodiment of the present invention to guide the drone to perform autonomous landing for wireless charging with the wireless charging coupling mechanism aligned has the following advantages:

[0071] On the one hand, when calculating the relative position and relative posture of the charging pile and the UAV through the visual positioning module, a concise, clear, operable and robust method should be used to reduce the amount of calculation to improve the accuracy of the UAV's autonomous landing;

[0072] On the other hand, the positioning slide on the charging pile can align the primary coil of the wireless charging coupling mechanism with the secondary coil located on the drone to ensure maximum efficiency in power transmission.

[0073] In one implementation of an embodiment of the present invention, in an embodiment of the present invention, when the drone has a charging demand and is flying toward a charging pile, a precise landing is achieved by adjusting the position horizontally and landing vertically.

[0074] The premise of the embodiment of the present invention is first to select a specific landing marker with simple shape features and single color features, and secondly, to fix a camera (such as a monocular camera) under the drone to reduce the impact of uncontrollable interference such as vibration during flight. On the drone side, the computer obtains the position information of the charging pile in the camera coordinate system based on the principle that the position of the drone in the camera coordinate system remains unchanged, thereby calculating the relative position of the drone and the charging pile. Figure 2 As shown, it is a flow chart of a wireless charging method for aligning a wireless charging coupling mechanism using a wireless charging system for a drone provided by an embodiment of the present invention; the method comprises the following steps:

[0075] Step 1: The drone reads its own power through the computer, and starts to return to charge when the power is lower than the set value. The computer navigates to the vicinity of the charging pile based on the drone location information obtained by the GPS module;

[0076] Step 2: Based on the location information of the drone obtained by the GPS module, the flight control system controls the drone to land at a preset height (for example, 10 meters) to ensure that the camera can capture the specific landing marker of the charging pile;

[0077] Step 3: Use the camera to collect image information, and the visual positioning module recognizes the specific landing marker of the charging pile through the image, and calculates the relative position of the drone and the charging pile in combination with the GPS module;

[0078] Step 4: The flight control system adjusts the flight posture of the drone according to the relative position of the drone and the charging pile, feeds back the flight data to the computer, controls the drone to land on the landing platform of the charging pile through information interaction between the computer and the flight control system, and sends a charging request instruction to the charging pile;

[0079] Step 5: After receiving the charging request instruction, the charging pile detects the position of the UAV on the landing platform through the microcontroller, thereby controlling the positioning slide to drive the primary coil to move to align with the secondary coil on the UAV, that is, to achieve alignment of the wireless charging coupling mechanism, thereby controlling the primary coil to continuously send wirelessly transmitted electric energy, so that the secondary coil receives the wirelessly transmitted electric energy sent by the primary coil, indicating that charging is possible; subsequently, the secondary coil receives the wirelessly transmitted electric energy sent by the primary coil to implement charging;

[0080] The charging method of the aligned coils in the present invention can ensure the maximum efficiency of power transmission.

[0081] Step 6: After the charging pile is fully charged, the primary coil stops sending wirelessly transmitted power;

[0082] Step 7: After the drone is fully charged, it will fly away to perform other tasks.

[0083] In the specific implementation of the embodiment of the present invention, in order to achieve efficient and convenient mobile wireless charging, the drone is designed to have a compact structure; among them, visual assisted landing is particularly important, which is related to whether the drone can land more accurately on the charging pile, thereby affecting the wireless charging action. Figure 3 As shown, Figure 1 The illustrated embodiment provides a schematic flow chart of aligning a wireless charging coupling mechanism in a wireless charging system of a drone, including the following steps:

[0084] S1, after the computer collects image information through the camera, the computer uses the color value extraction algorithm in the visual positioning module to first extract the binary image, eliminate the influence of noise through opening and closing operations, and obtain the outline of the binary image;

[0085] S2, then the visual positioning module obtains the contour perimeter and area data of each binary image; the circularity of each contour is calculated by the contour perimeter and area data of each binary image, and the specific landing marker of the charging pile is screened out according to the circularity of each contour (the larger the circularity value, the more round it is) compared with the set threshold; considering the characteristic information of the interference under the terrain environment, the specific landing marker in the present invention is designed to be circular;

[0086] S3, the visual positioning module calculates the offset pixel position from the center of the contour of the identified binary image to the center of the camera field of view, which is the relative pixel position of the drone and the charging pile. The relative pixel position can be used to represent the relative position of the drone and the charging pile;

[0087] S4, the computer controls the flight control system to adjust the position of the drone according to the offset pixel position to reduce the above calculated offset pixel position, and then vertically lands at a certain height (for example, 0.5m), and repeats the above operation (repeats S1 to S4) until it lands at the charging station;

[0088] S5, the microcontroller in the charging pile controls the movement of the movable slide so that the coil of the coupling mechanism is automatically aligned.

[0089] The wireless charging system and aligned wireless charging method of the drone provided by the embodiment of the present invention are specifically a wireless charging method for aligning the wireless charging coupling mechanism in the drone based on visual multi-sensor fusion, and provide a wireless charging system and method for aligning the wireless charging coupling mechanism by using a specific landing marker to guide the drone to land autonomously when the drone is low on power. In the specific implementation, firstly, navigation is performed to the vicinity of the charging pile through GPS data; secondly, the color of the specific landing marker is recognized by image and the contour information is extracted, the circularity of each contour is calculated to identify the logo pattern, and the relative position of the specific landing marker and the drone is calculated, and then the position of the drone is adjusted to make the drone land on the charging pile, so that the drone can achieve "point-to-point" precise landing. In addition, the positioning slide of the charging pile can align the primary coil of the wireless charging coupling mechanism with the secondary coil of the drone, realize wireless charging, and ensure the maximum efficiency of power transmission.

[0090] The wireless charging system and aligned wireless charging method of the drone provided by the embodiment of the present invention are described in detail through a specific embodiment as follows.

[0091] Once the wireless charging system tracks and aligns the primary coil in the wireless charging coupling mechanism with the secondary coil on the drone, the most efficient power transmission can be guaranteed.

[0092] The focus of the present invention is to find the precise landing and coupling mechanism alignment after low battery. The verification of the relevant algorithms includes: landing marker selection, color value extraction, target recognition, offset calculation, landing on the charging pile, and automatic alignment and charging of the wireless charging coupling mechanism. The implementation process of the above algorithm verification is described in detail as follows:

[0093] (1) Selection of specific landing markers

[0094] Self-designed markers require matching algorithms and hardware that are compatible with the markers. In order to design an autonomous landing platform for drones in this project, the selected marker image features are too complex, which will increase the amount of calculation, burden the onboard computer, and reduce the real-time performance of image processing. There is an infrared positioning slide in the drone charging station for aligning the coil of the wireless charging coupling mechanism, and there is no requirement for the landing direction of the drone during wireless charging, so a single color marker is selected here. Figure 4 As shown, it is a schematic diagram of a specific landing marker selected in an embodiment of the present invention, wherein the color can be any single color, but it must correspond to the algorithm.

[0095] (2) Color value extraction

[0096] The image captured by the drone's camera is an RGB color image. Using the characteristics of the RGB model that all colors can be described by three coordinate values ​​of R (red), G (green) and B (blue), the RGB component values ​​of all colors in the image are compared, elements that match the color of the landmark point are retained, and interfering elements are removed. When the drone identifies a landmark point, it extracts the RGB component value of the element, retains the element with the same RGB value as the landmark point, and assigns other elements to white to remove them, so as to reduce the impact of environmental factors such as lighting and other buildings, and better filter out the interference of other color noise, laying the foundation for target recognition and orientation analysis.

[0097] Since the HSV color space uses more intuitive data to describe color, H (hue), S (saturation), V (brightness), it is easier to extract specific color information. In order to extract the color values, the image is converted from the RGB color space to the HSV space. The result is as follows Figure 5 FIG. 1 is a schematic diagram of converting an image from an RGB color space to an HSV color space in an embodiment of the present invention.

[0098] The color representation range in the HSV space is shown in Table 1:

[0099] Table 1 HSV color system

[0100]

[0101] like Figure 6 , which is a schematic diagram of a specific landing marker extracted from a captured image according to the color range in Table 1 in an embodiment of the present invention.

[0102] Depend on Figure 6 It can be seen that there are a lot of noises. Opening operation can generally smooth the contours of the image, weaken the narrow parts, and remove the thinner protrusions. Image opening operation is the process of image corrosion and expansion in sequence. After the image is corroded, the noise will be removed, but at the same time, the image will be compressed. Then the corroded image is expanded to remove the noise while retaining the original image. Figure 7 , which is a schematic diagram of the result of the image opening operation in an embodiment of the present invention. So far, the contour information with the same color as the logo has been obtained, and the logo is identified by the circularity of the contour as follows.

[0103] (3) Identify the target

[0104] The perimeter and area of ​​the contour are definitely not the actual perimeter and area of ​​the object. The perimeter and area calculated by the computer are all in pixels. The perimeter is the number of contour points (with 1 pixel as the step), and the area is the number of all pixels surrounded by the contour. Therefore, the perimeter and area of ​​the contour can be calculated based on the pixel information of the contour. Here, the target identification is identified based on the circularity of the contour. The larger the circularity value of the contour, the more round it is.

[0105] The circularity calculation formula is:

[0106] e = (4π*area) / (circumference*circumference)

[0107] The circularity of the contour is calculated based on the color extracted in the previous text, and the circularity of the contour is calculated by Figure 7 The circularity ranking of each contour is shown in Table 2:

[0108] Table 2 Ranking of circularity of each contour

[0109] Serial number Circularity 1 0.890548 2 0.389473 3 0.280256 4 0.174614 5 0.17348 6 0.231325 7 0.129603

[0110] Since the drone may be tilted when taking photos during flight, which may cause changes in the roundness, the threshold is set to a roundness greater than 0.7. Figure 8 , which is a schematic diagram of an image recognition result obtained by roundness screening in an embodiment of the present invention.

[0111] (4) Calculate offset

[0112] The center of the image captured by the camera is recorded as the two-dimensional coordinate position of the drone, CenterPoint (cx, cy), and the contour center of the binary image is identified as Target Point (tx, ty). Ideally, when the coordinates of CenterPoint are equal to the coordinates of Target Point, it is considered that there is no offset. The offset pixel calculation of the drone is:

[0113] Δx = cx - tx;

[0114] Δy=cy-ty;

[0115] according to Figure 8 The data calculation results are:

[0116] The offset in the x direction is: -22.880028px;

[0117] The offset in the y direction is: -53.360977px;

[0118] Algorithm time: 0.1998 seconds;

[0119] By quickly adjusting the position of the drone according to the offset in two directions, the drone can land on the wireless charging pile on a two-dimensional plane and prepare for charging.

[0120] (5) Landing at the charging station

[0121] According to the offset calculated in the previous step, the relative offset between the drone and the charging pile in the X and Y directions is obtained. Each time, the drone is adjusted a small distance in both directions until the offset is less than the set value and then it lands. Repeat the above operation until the drone's height is less than the set value and then it lands vertically, thus landing on the charging pile.

[0122] (6) Wireless charging coupling mechanism automatically aligns and charges

[0123] For drones that land on wireless charging piles, in order to maximize the charging efficiency, the charging piles in the embodiments of the present invention use an infrared grating module + dual-coordinate positioning slide structure to locate and track the drones and achieve precise alignment of the primary and secondary coils. Fig. 9 , which is a schematic diagram of the structure of a charging pile in a wireless charging system for a drone provided by an embodiment of the present invention; Fig. 9 Figure a shows the state of the drone before landing, and figure b shows the state of the drone after landing.

[0124] like Fig. 9 As shown in the figure, the infrared grating module consists of a transmitter and a receiver, and has the advantages of fast response, high precision, and anti-interference. It can identify multiple points and send corresponding coordinate information through the serial port to facilitate drone positioning.

[0125] like Fig. 9 As shown, the positioning slide is configured as a dual-coordinate positioning slide, including: slide Y axes symmetrically arranged on both sides of the bottom of the landing platform, and slide X axes arranged between the two slide Y axes, the primary coil is arranged on the slide X axis through a coil bracket, and the position adjustment of the primary coil is controlled by the axial movement of the slide X axis itself and the movement of the slide X axis along the slide Y axis.

[0126] In specific implementation, the dual-coordinate positioning slide is composed of motor drive and belt guide transmission, and has the characteristics of high efficiency, high precision, low wear, long life, low friction coefficient, energy saving and low consumption, strong versatility, and compact structure. It can be driven by DC servo motor, AC servo motor, and stepper motor. The stepper motor is pulse controlled. When a pulse is given to the motor, the motor rotates an angle. The dual-coordinate positioning workbench controlled by the stepper motor has the advantages of high precision, simple control method, and low cost, which is convenient for the precise movement of the primary coil.

[0127] like Fig.10As shown, it is a schematic diagram of the program for automatic alignment of the wireless charging coupling mechanism in the embodiment of the present invention. First, it is determined whether there is a reset flag set. If so, the infrared reading function and the motor pulse calculation function are reset, and each counter is cleared; if there is no reset flag set, the Timer0 counter is configured and turned on to enable interruption. Then wait for the drone to land on the wireless charging platform. When the drone has not landed, initialize each parameter and block the PWM wave, and the X and Y axis motors do not move; after the drone lands, the timing starts, and the data packets sent by the infrared positioning frame are read and stored, and then the X and Y axis coordinates of the center point of the drone are solved from each packet of data, and the number of pulses required for the X and Y axis positioning motors are calculated, and PWM is enabled, and the motor is controlled to drive the primary coil to run directly below the drone. Automatic alignment is completed within 3 seconds. When 3 seconds are reached, the Timer0 timer interrupt is disabled and wireless charging starts.

[0128] By using the wireless charging system for the drone provided by the embodiment of the present invention, when the drone returns and lands at any position of the wireless charging pile, the main controller can solve the center point coordinates of the current drone through the infrared grating module, and then send a corresponding pulse command to the dual-coordinate positioning slide, automatically transporting the transmitting coil to the bottom of the drone, so that the center of the transmitting coil and the center of the receiving coil are aligned, thereby realizing the maximum power transmission of electrical energy and charging the lithium battery of the drone.

[0129] The technical solution provided by the present invention utilizes machine vision positioning technology and an infrared slide-assisted GPS sensor to achieve precise landing of a UAV on a wireless charging pile, thereby realizing a method for wireless charging of the UAV.

[0130] Although the embodiments disclosed in the present invention are as above, the contents are only embodiments adopted to facilitate understanding of the present invention and are not intended to limit the present invention. Any technician in the field to which the present invention belongs can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A wireless charging system for an unmanned aerial vehicle, characterized in that: include: Drones, charging piles, and wireless charging coupling mechanisms; The wireless charging coupling mechanism includes: a primary coil arranged on the charging pile, and a secondary coil arranged on the drone; The drone includes: a computer, a camera, a flight control system, a GPS module, a visual positioning module and a secondary coil of a wireless charging coupling mechanism respectively connected to the computer, and a battery for supplying power to various electrical devices in the drone; The GPS module is used to obtain the location information of the drone; The computer is used to obtain the position information of the drone based on the GPS module. When the drone lands at a certain height, the camera is used to collect image information and transmit it to the visual positioning module inside the computer for image processing; The visual positioning module is used to identify the specific landing marker of the charging pile through images and calculate the relative position of the drone and the charging pile; The flight control system is used to control the flight of the drone to land on the landing platform of the charging pile by adjusting the flight posture of the drone and feeding back flight data to the computer according to the relative position of the drone and the charging pile, and to send a charging request instruction to the charging pile through information interaction between the computer and the flight control system; The charging pile includes: a positioning slide, a primary coil of a coupling mechanism fixedly mounted on the positioning slide, a landing platform mounted above the positioning slide and the primary coil, and a microcontroller electrically connected to the primary coil of the positioning slide respectively; The microcontroller is used to detect the position of the drone on the landing platform after receiving the charging request instruction, thereby controlling the positioning slide to drive the primary coil to move to align with the secondary coil on the drone, and controlling the primary coil to continuously send wirelessly transmitted electric energy, so that the secondary coil receives the wirelessly transmitted electric energy sent by the primary coil, thereby implementing charging.

2. The wireless charging system for an unmanned aerial vehicle according to claim 1, characterized in that: The camera is fixedly installed under the drone, and a specific landing marker is pre-set on the landing platform of the charging pile; The computer obtains the position information of the charging pile in the camera coordinate system based on the principle that the position of the drone in the camera coordinate system remains unchanged, thereby calculating the relative position of the drone and the charging pile.

3. The wireless charging system for an unmanned aerial vehicle according to claim 2, characterized in that: The visual positioning module in the computer calculates the relative position of the drone and the charging pile in the following way: According to the image information collected by the camera, the binary image is first extracted through the color value extraction algorithm, and the influence of noise is eliminated through opening and closing operations to obtain the contour of the binary image; the contour perimeter and area data of each binary image are obtained, and the circularity of each contour is calculated through the contour perimeter and area data of each binary image. The specific landing marker of the charging pile is screened out by comparing the circularity of each contour with the set threshold; the offset pixel position is calculated from the center of the contour of the identified binary image to the center of the camera's field of view as the relative pixel position of the drone and the charging pile.

4. The wireless charging system for an unmanned aerial vehicle according to claim 3, characterized in that: The method of controlling the drone to land on the landing platform of the charging pile includes: The computer controls the flight control system to adjust the position of the UAV according to the offset pixel position, and then vertically lands at a preset height (for example, 0.5 m) after reducing the offset pixel position calculated above, and repeats the operation of calculating the offset pixel position and vertically landing until the UAV lands on the landing platform of the charging pile; thereby, the microcontroller in the charging pile controls the movement of the movable slide so that the coil of the coupling mechanism is automatically aligned.

5. The wireless charging system for an unmanned aerial vehicle according to any one of claims 1 to 4, characterized in that: An infrared grating module is provided on the landing platform of the charging pile to identify multiple points and send coordinate information through the serial port to realize the positioning of the drone; The positioning slide is configured as a dual-coordinate positioning slide, including: slide Y axes symmetrically arranged on both sides of the bottom of the landing platform, and slide X axes arranged between the two slide Y axes. The primary coil is arranged on the slide X axis through a coil bracket, and the position adjustment of the primary coil is controlled by the axial movement of the slide X axis itself and the movement of the slide X axis along the slide Y axis.

6. An alignment wireless charging method for a wireless charging system of an unmanned aerial vehicle, characterized in that: A wireless charging method for aligning a wireless charging coupling mechanism using a wireless charging system of a drone as claimed in any one of claims 1 to 5 comprises: Step 1: The drone reads its own power through the computer, and starts to return to charge when the power is lower than the set value. The computer navigates to the vicinity of the charging pile based on the drone location information obtained by the GPS module; Step 2: Based on the location information of the drone obtained by the GPS module, the flight control system controls the drone to land at a preset height to ensure that the camera can capture the specific landing marker of the charging pile; Step 3: Use the camera to collect image information, and the visual positioning module recognizes the specific landing marker of the charging pile through the image, and calculates the relative position of the drone and the charging pile in combination with the GPS module; Step 4: The flight control system adjusts the flight posture of the drone according to the relative position of the drone and the charging pile, feeds back the flight data to the computer, controls the drone to land on the landing platform of the charging pile through information interaction between the computer and the flight control system, and sends a charging request instruction to the charging pile; Step 5: After receiving the charging request instruction, the charging pile detects the position of the UAV on the landing platform through the microcontroller, thereby controlling the positioning slide to drive the primary coil to move to align with the secondary coil on the UAV, that is, to align the wireless charging coupling mechanism, thereby controlling the primary coil to continuously send wirelessly transmitted power, so that the secondary coil receives the wirelessly transmitted power sent by the primary coil, thereby implementing charging; Step 6: After the charging pile is fully charged, the primary coil stops sending wirelessly transmitted power; Step 7: After the drone is fully charged, it will fly away to perform other tasks.

7. The alignment wireless charging method of the wireless charging coupling mechanism of the drone according to claim 6, characterized in that: Before step 1, the method further includes: A specific landing marker is formed on the landing platform of the charging pile, and the specific landing marker is a circular marker with a single color attached to the platform.

8. The alignment wireless charging method of the wireless charging coupling mechanism of the drone according to claim 7, characterized in that: The method of calculating the relative position of the drone and the charging pile in step 3 includes: Step 31, according to the image information collected by the camera, a binary image is first extracted by a color value extraction algorithm, and the influence of noise is eliminated by an opening and closing operation to obtain the outline of the binary image; Step 32, obtaining the contour perimeter and area data of each binary image, calculating the circularity of each contour through the contour perimeter and area data of each binary image, and screening out the specific landing marker of the charging pile according to the comparison of the circularity of each contour with the set threshold; In step 33, the offset pixel position is calculated from the center of the contour of the binary image to the center of the camera field of view, which is used as the relative pixel position of the drone and the charging pile.

9. The alignment wireless charging method of the wireless charging coupling mechanism of the drone according to claim 8, characterized in that: In step 4, controlling the drone to fly and land on the landing platform of the charging pile includes: The flight control system is controlled to adjust the position of the drone according to the offset pixel position. After reducing the offset pixel position calculated in step 33, the drone vertically lands at a preset height, and steps 31 to 33 and the vertical landing operation of step 4 are repeated until the drone lands on the landing platform of the charging pile. The microcontroller in the charging pile controls the movement of the movable slide so that the coil of the coupling mechanism is automatically aligned.

10. The alignment wireless charging method of the wireless charging coupling mechanism of the drone according to claim 8, characterized in that: The pixel position offset in step 33 includes: The center of the image captured by the camera is recorded as the two-dimensional coordinate position of the drone, CenterPoint (cx, cy), and the contour center of the identified binary image is recorded as Target Point (tx, ty); the offsets of the offset pixel position of the drone in the x and y directions are: Δx = cx - tx; Δy=cy-ty.

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