Unmanned aerial vehicle hanging load release automatic shimmy damping device and control method

Abstract

The invention belongs to the technical field of unmanned aerial vehicle hanging transportation, and particularly relates to an unmanned aerial vehicle hanging load releasing automatic shimmy damping device and a control method. The unmanned aerial vehicle hanging load releasing automatic shimmy damping device comprises a load hanging mounting plate, the load hanging mounting plate is connected with an unmanned aerial vehicle through a mounting hole, and two digital steering engines are mounted at the bottom of the load hanging mounting plate and are arranged up and down; the two digital steering engines are connected through a connecting piece, the hanging load is connected with the digital steering engine below the hanging load through a putting mechanism, a video collecting device is further arranged at the bottom of the load hanging installation plate, and a data processing controller is installed at the top of the load hanging installation plate. A video acquisition device is used for acquiring the relative position of a hanging load and a putting point, and the relative position is used as the input of a data processing controller; the data processing controller outputs rudder arm rotation direction and angle instructions to the two digital steering engines by adopting a classic PID control algorithm according to video input, and finally controls the hanging load to be close to a putting point, so that the purpose of shimmy damping is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of unmanned aerial vehicle (UAV) suspended transportation, and particularly relates to an automatic anti-sway device and control method for UAV suspended load dropping. Background Art

[0002] The UAV suspended transportation technology is a method of using UAVs for cargo transportation. This technology is usually used to transport goods from one location to another, especially in cases where ground transportation is difficult or impractical. The UAV suspended transportation technology can improve transportation efficiency, reduce costs, and reach areas that cannot be reached by traditional transportation methods. When performing a suspended transportation task, the UAV suspends the cargo under the fuselage through a special suspension device and then flies to the destination along a predetermined route. This technology has broad application prospects in fields such as rescue, logistics distribution, and agricultural spraying.

[0003] When the load suspended by the UAV is accurately dropped, it needs to change from a moving state to a relatively stable state. This process is usually interfered by factors such as external wind, air flow, and the downwash flow of the UAV's own rotors, making it difficult to achieve quickly, thus affecting the dropping accuracy. Seriously, the swing of the suspended load and the UAV flight produce harmful coupling, affecting the stable control of the UAV itself and causing flight accidents. Summary of the Invention

[0004] The purpose of the present invention is to provide an automatic anti-sway device and control method for UAV suspended load dropping to solve the sway problem during UAV suspended load dropping.

[0005] The present invention is achieved by the following technical solutions:

[0006] An automatic anti-sway device for UAV suspended load dropping, including a load suspension mounting plate, characterized in that the load suspension mounting plate is provided with mounting holes, and the load suspension mounting plate is connected to the UAV through the mounting holes. A digital servo is installed at the bottom of the load suspension mounting plate. There are two digital servos arranged vertically, and the two digital servos are connected by a connecting member. The suspended load is connected to the lower digital servo through a dropping mechanism. A video acquisition device is also provided at the bottom of the load suspension mounting plate, and a data processing controller is installed at the top of the load suspension mounting plate.

[0007] Preferably, the video acquisition device is a camera with data transmission function, and the camera's field of view is perpendicular to the ground for observing the relative position between the suspended load and the dropping point.

[0008] Preferably, the data processing controller is a processor with data processing and output functions, which is used to process the video data of the video acquisition device in real time, and output instructions to two digital servos through a control algorithm to control the rotation angle of the servo arm.

[0009] The second aspect of the present invention provides a control method for an automatic anti-swing device for an unmanned aerial vehicle hanging load dropping, which is implemented based on the above automatic anti-swing device, and includes the following steps:

[0010] S1: After the unmanned aerial vehicle hanging the load flies to the area near the target dropping point, it hovers above the target dropping point, and the video acquisition device is powered on to work and perform video acquisition;

[0011] S2: The video acquisition device continuously acquires the relative position relationship between the hanging load and the target dropping point, and transmits the video data to the data processing controller; after receiving the video data, the data processing controller performs image processing;

[0012] S3: According to the processed image, the data processing controller automatically detects and tracks the position of the hanging load in the picture through the contour detection method, and compares the position of the hanging load with the position of the dropping point; specifically: taking the dropping point as the origin coordinate, a horizontal rectangular coordinate system is established, the position of the hanging load in the picture is marked in the coordinate system, and the projection distance from the position of the hanging load to the coordinate axis is calculated in pixel points;

[0013] S4: The data processing controller adopts the classical PID control method. The data processing controller takes the projection distance calculated in step S3 as the error input of the PID control method, and determines the target angle of deflection of the digital servo according to the projection distance;

[0014] S5: According to the classical PID control method, by means of manual adjustment or using genetic algorithms, the three key parameters in the PID control method are accurately determined: the proportional coefficient (K p ), the integral coefficient (K i ), and the differential coefficient (K d );

[0015] S6: After the PID parameters are determined, the deflection directions and deflection angles of the two digital servos can be calculated. The data processing controller outputs the deflection instructions through the pigpio library (the conversion instruction libraries for different digital servos may be different) to control the deflection of the digital servos;

[0016] S7: The video acquisition device acquires the positions of the hanging load and the dropping point again, and repeats steps S2-S6 until the error in step S4 is less than the preset target, and it can be considered that the anti-swing of the hanging load is completed.

[0017] Preferably, the image processing includes HSV color space conversion and morphological operations.

[0018] Preferably, the HSV color space conversion converts the image from the traditional RGB color space to the HSV color space.

[0019] Preferably, the morphological operations include dilating and eroding the image to improve the image quality.

[0020] Preferably, the basic steps of the classical PID control method are as follows:

[0021] a. Initialize the three parameters of the PID controller: proportional coefficient (K p ), integral coefficient (K i ), and derivative coefficient (K d );

[0022] b. Read the angular position of the current digital servo;

[0023] c. Calculate the difference between the target angle and the current angle, denoted as e(t);

[0024] d. Calculate the control quantity according to the PID formula;

[0025] e. Control quantity = K p *e(t) + K i *∫e(t)dt + K d *de(t) / dt;

[0026] f. Convert the calculated control quantity into a signal that the digital servo can receive and output it to the digital servo.

[0027] g. Update the integral term and record the current time for calculating the derivative term.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. The present invention uses a video acquisition device to collect the relative position of the suspended load and the dropping point as the input of the data processing controller; the data processing controller adopts the classical PID control algorithm according to the video input, outputs instructions on the rotation direction and angle of the steering arms to two digital servos, and finally controls the suspended load near the dropping point to achieve the purpose of reducing swing.

[0030] 2. The present invention controls the front-back and left-right swings respectively through double-servo control, so that the suspended load quickly and stably reaches the target position.

[0031] 3. The present invention integrates a digital servo, a video acquisition device, and a data processing controller on the same load suspension mounting plate, featuring a compact structure and being more suitable for the limited load space of unmanned aerial vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 : A three-dimensional structural schematic diagram of an automatic anti-sway device for an unmanned aerial vehicle suspension load dropping of the present invention;

[0033] Figure 2 : A front view of an automatic anti-sway device for an unmanned aerial vehicle suspension load dropping of the present invention;

[0034] Figure 3 : A left view of an automatic anti-sway device for an unmanned aerial vehicle suspension load dropping of the present invention;

[0035] Figure 4 : A top view of an automatic anti-sway device for an unmanned aerial vehicle suspension load dropping of the present invention;

[0036] Figure 5 : A working process schematic diagram of the control method of the automatic anti-sway device for an unmanned aerial vehicle suspension load dropping in the present invention;

[0037] In the figure: 1, load suspension mounting plate; 2, digital servo; 3, video acquisition device; 4, data processing controller; 5, mounting hole; 6, connecting piece. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] In order to more clearly understand the above-mentioned objects, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Many specific details are set forth in the following description in order to provide a thorough understanding of the present invention. However, the present invention may be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0040] Such as Figures 1-4As shown in the figure, an automatic pendulum reduction device for an unmanned aerial vehicle (UAV) to suspend and drop a load includes a load suspension mounting plate 1. An installation hole 5 is provided on the load suspension mounting plate 1. The load suspension mounting plate 1 is bolted to the UAV through the installation hole 5. A digital servo 2 is installed at the bottom of the load suspension mounting plate 1. There are two digital servos 2 arranged vertically. The two digital servos 2 are connected by a connecting piece 6. The suspended load is connected to the lower digital servo 2 through a dropping mechanism. The front-back and left-right movement of the suspended load is controlled by the rotation of the servo arm of the digital servo 2. A video acquisition device 3 is also provided at the bottom of the load suspension mounting plate 1. The video acquisition device 3 is a camera with data transmission function. The field of view of the camera is perpendicular to the ground, and it is used to observe the relative position between the suspended load and the dropping point. A data processing controller 4 is installed at the top of the load suspension mounting plate 1. The data processing controller 4 is a processor with data processing and output functions, which is used to process the video data of the video acquisition device 3 in real time, and output instructions to the two digital servos 2 through a control algorithm to control the rotation angle of the servo arm.

[0041] As Figure 5 shown, based on the above automatic pendulum reduction device for an unmanned aerial vehicle to suspend and drop a load, its control method includes the following steps:

[0042] S1: During the process of the UAV performing a specific task, when the suspended load it carries needs to be dropped at a designated location, the UAV will fly to the adjacent area of the target dropping point. After arriving at this area, the UAV will perform a hovering operation, and the video acquisition device 3 will be automatically started to perform video acquisition.

[0043] S2: The video acquisition device 3 is responsible for capturing the relative position relationship between the suspended load and the target dropping point in real time, and transmitting the collected video data to the data processing controller 4 in real time. After receiving the video data, the data processing controller 4 performs image processing. The image processing mainly includes HSV color space conversion and morphological operations.

[0044] The HSV color space conversion converts the image from the traditional RGB color space to the HSV color space, which can more conveniently process and analyze the color of the image.

[0045] The morphological operations improve the image quality, highlight important features, or remove noise and irrelevant information by operations such as image dilation and erosion.

[0046] S3: According to the processed image, the data processing controller 4 automatically detects and tracks the position of the suspended load in the picture through the contour detection method, and compares the position of the suspended load with the position of the dropping point. Specifically:

[0047] (1) Taking the placement point as the reference origin coordinate (0, 0), a horizontal rectangular coordinate system is constructed. In this coordinate system, the position of the suspended load in the picture will be accurately marked as a coordinate point (x, y).

[0048] (2) The data processing controller 4 will conduct an in-depth analysis of the position of the suspended load to determine its four quadrants in the rectangular coordinate system, that is, control the clockwise or counterclockwise deflection of two digital servos according to the positive and negative of x and y.

[0049] (3) For precise calculation, the controller quantifies the projection distances of the position of the suspended load onto the coordinate axes in pixel points, and calculates the values of |x| and |y| respectively, that is, the projection distances of the suspended load to the origin in the horizontal and vertical directions.

[0050] S4: The data processing controller 4 adopts the classical PID control method. The data processing controller 4 takes the projection distances |x| and |y| calculated in step S3 as the error inputs of the PID controller, and determines the target angle of the digital servo deflection according to the projection distances.

[0051] S5: According to the classical PID control method, through manual adjustment or by using the intelligent optimization technology of genetic algorithm, the three key parameters in the PID control method are accurately determined: proportional coefficient (K p ), integral coefficient (K i ) and differential coefficient (K d ). The basic steps are as follows:

[0052] a. Initialize the three parameters of the PID controller: proportional coefficient (K p ), integral coefficient (K i ) and differential coefficient (K d );

[0053] b. Read the angular position of the current digital servo 2;

[0054] c. Calculate the difference between the target angle and the current angle, denoted as e(t);

[0055] d. Calculate the control quantity according to the PID formula;

[0056] e. Control quantity = K p * e(t) + K i * ∫e(t)dt + K d * de(t) / dt;

[0057] f. Convert the calculated control quantity into a signal that the digital servo 2 can receive, such as a PWM pulse width, and output it to the digital servo 2.

[0058] g. Update the integral term and record the current time for calculating the differential term.

[0059] The proportional coefficient is responsible for adjusting the response intensity of the system to the current error, the integral coefficient ensures that the long-term cumulative error can be eliminated, and the differential coefficient predicts the trend of future errors for early adjustment.

[0060] In practical applications, it is necessary to adjust and optimize the proportional coefficient (K p ), integral coefficient (K i ), and differential coefficient (K d ) to adapt to the characteristics of different digital servo systems and dynamic response requirements. Through the reasonable configuration of these parameters, the control system can be made more stable and accurate to achieve the desired control objectives.

[0061] S6: After the PID parameters are determined, the deflection direction and deflection angle of the two digital servos 2 can be calculated. The data processing controller 4 outputs the deflection command through the pigpio library (the conversion instruction libraries for different digital servos may be different) to control the deflection of the digital servos.

[0062] S7: The video acquisition device 3 collects the positions of the suspended load and the dropping point again, and repeats steps S2 - S6 until the error in step S4 is less than the preset target, and it can be considered that the suspended load has completed the swing reduction.

Claims

1. An automatic pendulum reduction device for an unmanned aerial vehicle's suspended load dropping, comprising a load suspension mounting plate (1), characterized in that , an installation hole (5) is formed on the load suspension mounting plate (1). The load suspension mounting plate (1) is connected to the drone through the installation hole (5). A digital servo (2) is installed at the bottom of the load suspension mounting plate (1). There are two digital servos (2) arranged vertically. The two digital servos (2) are connected by a connecting piece (6). The suspended load is connected to the lower digital servo (2) through a dropping mechanism. A video acquisition device (3) is also arranged at the bottom of the load suspension mounting plate (1). A data processing controller (4) is installed at the top of the load suspension mounting plate (1).

2. The automatic anti-swing device for dropping a suspended load of a drone according to claim 1, wherein The video acquisition device (3) is a camera with data transmission function. The field of view of the camera is perpendicular to the ground and is used to observe the relative position between the suspended load and the dropping point.

3. The automatic anti-swing device for the drone suspension load dropping according to claim 1, wherein The data processing controller (4) is a processor with data processing and output functions. It is used to process the video data of the video acquisition device (3) in real time, and output instructions to the two digital servos (2) through a control algorithm to control the rotation angle of the servo arm.

4. A control method for an automatic pendulum reduction device of an unmanned aerial vehicle hanging load dropping, implemented based on the device described in any one of claims 1-3, characterized in that, It includes the following steps: S1: After the drone suspends the load and flies to the area near the target dropping point, it hovers above the target dropping point. The video acquisition device (3) is powered on and starts video acquisition. S2: The video acquisition device (3) continuously acquires the relative position relationship between the suspended load and the target dropping point, and transmits the video data to the data processing controller (4). After receiving the video data, the data processing controller (4) performs image processing. S3: Based on the processed image, the data processing controller (4) automatically detects and tracks the position of the suspended load in the picture through the contour detection method, and compares the position of the suspended load with the position of the dropping point. Specifically: taking the dropping point as the origin coordinate, a horizontal rectangular coordinate system is established, the position of the suspended load in the picture is marked in the coordinate system, and the projection distance from the position of the suspended load to the coordinate axis is calculated in pixel units. S4: The data processing controller (4) adopts the classical PID control method. The data processing controller (4) takes the projection distance calculated in step S3 as the error input of the PID control method, and determines the target angle of deflection of the digital servo according to the projection distance. S5: According to the classical PID control method, precisely determine the three key parameters in the PID control method by manual adjustment or by using the genetic algorithm: the proportional coefficient (K p ), the integral coefficient (K i ), and the derivative coefficient (K d ); S6: After the PID parameters are determined, the deflection direction and deflection angle of the two digital servos (2) can be calculated. The data processing controller (4) outputs the deflection instruction through the pigpio library (the conversion instruction libraries for different digital servos may be different) to control the deflection of the digital servo. S7: The video acquisition device (3) acquires the positions of the suspended load and the dropping point again, and repeats steps S2 - S6 until the error in step S4 is less than the preset target, and it can be considered that the suspended load has completed pendulum reduction.

5. The control method of an automatic pendulum reduction device for an unmanned aerial vehicle suspension load dropping, as described in claim 4, is characterized in that, The image processing includes HSV color space conversion and morphological operations.

6. The control method of an automatic anti-swing device for drone suspended load dropping according to claim 5, characterized in that, The HSV color space conversion converts the image from the traditional RGB color space to the HSV color space.

7. The control method of an automatic anti-swing device for a drone suspended load dropping according to claim 5, characterized in that, The morphological operations include dilation and erosion operations on the image to improve the image quality.

8. The control method of an automatic pendulum reduction device for an unmanned aerial vehicle to suspend and release a load according to claim 4, characterized in that, The basic steps of the classical PID control method are as follows: a. Initialize the three parameters of the PID controller: proportional coefficient (K p ), integral coefficient (K i ), and derivative coefficient (K d ); b. Read the angular position of the current digital servo (2); c. Calculate the difference between the target angle and the current angle, denoted as e(t); d. Calculate the control quantity according to the PID formula; e. Control quantity = K p *e(t) + K i *∫e(t)dt + K d *de(t) / dt; f. Convert the calculated control quantity into a signal that the digital servo (2) can receive and output it to the digital servo (2); g. Update the integral term and record the current time for calculating the differential term.

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