WO2022088562A1

WO2022088562A1 - Multi-rotor spray rod structure and control method therefor

Info

Publication number: WO2022088562A1
Application number: PCT/CN2021/077616
Authority: WO
Inventors: 沈跃; 张念; 孙志伟; 王德伟; 刘慧�
Original assignee: 江苏大学
Priority date: 2020-10-26
Filing date: 2021-02-24
Publication date: 2022-05-05
Also published as: CN112352759A

Abstract

Disclosed are a multi-rotor spray rod structure and a control method therefor. The multi-rotor spray rod structure comprises a support rod (10); multiple rotors, motors (2), connection flanges (3), pesticide liquid pipes (4), nozzles (5), GPS modules (7), a vision module (8), a pesticide liquid and battery box assembly (11), and a millimeter-wave radar (13) are provided on the support rod; multiple pairs of rotors are symmetrically distributed on the support rod; the rotors comprise auxiliary rotors, adjusting rotors, and main rotors. The GPS modules are used for providing precise GPS data for a controller during path planning and flight stages; the vision module and the millimeter-wave radar are also symmetrically fixedly at both sides of the multi-rotor spray rod, respectively, and extend downwards by means of supports after being fixed by means of the connection flanges, and are used for measuring a moving speed and the height of the spray rod. According to the multi-rotor spray rod structure, when the spray rod works in edge and corner areas of farmland, the rotors can be controlled, by controlling the multiple pairs of rotors to be in different attitudes, to enable the spray rod to perform a yawing movement, and the multiple nozzles of the spray rod are controlled according to the density of crops, thereby achieving accurate variable spraying.

Description

A multi-rotor boom structure and its control method

technical field

The invention relates to a multi-rotor spray rod structure which can control the rotor to make the yaw movement when working in the corner area of the farmland, and belongs to the technical field of agricultural machinery automation and flight control.

Background technique

In the process of spraying pesticides on crops, traditional ground agricultural machinery faces difficulties such as cumbersome machines and the need for special roads, which makes plant protection drones more and more popular among growers in recent years. However, plant protection drones also encountered some difficulties in the operation process, such as short battery life, waste of chemical liquid in irregular operation areas, or repeated spraying.

SUMMARY OF THE INVENTION

Based on the above-mentioned deficiencies of the prior art, the present invention discloses a multi-rotor boom structure that is convenient and flexible, and can control the rotor to make the yaw movement.

The technical scheme of the present invention includes: a multi-rotor spray rod structure, comprising a support rod (10), and the support rod (10) is provided with a rotor, a motor (2), a connection flange (3), a liquid medicine pipeline ( 4), spray head (5), GPS module, vision module (8), liquid medicine and battery box assembly (11), millimeter wave radar (13); a plurality of pairs of rotors are symmetrically distributed on the support rod (10). Including auxiliary rotors, regulating rotors and main rotors, the main rotors provide most of the lift required for the boom to fly, and the angles of the auxiliary rotors and regulating rotors can be adjusted to provide lift for the overall boom and control the attitude of the boom, and at the same time The downward airflow generated by the downward airflow can accelerate the liquid medicine to adhere to the surface of the crops; the liquid medicine and the battery box assembly (11) are fixed in the center of the support rod (10), and the two ends of the support rod (10) are provided with auxiliary rotors, and the auxiliary rotors and Adjusting rotors are arranged between the legs of the support rod (10), and main rotors are symmetrically arranged at the two ends adjacent to the liquid medicine and the battery box assembly (11); In the layout of the paddle, the nozzle corresponding to the lower end of the rotor is replaced with a rotor of the same model and opposite direction to provide greater lift for the boom; The lower end is connected with a motor (2), which provides power for the rotor. The motor (2) is connected with a connecting flange (3), and the lower end of the connecting flange (3) is a liquid medicine pipeline (4), and the connecting flange (3) connects the motor. (2), the liquid medicine pipeline (4) is tightly fixed, and the liquid medicine pipeline (4) connects the nozzles (5) and provides the liquid medicine for the spray rod; the GPS module is tightly and symmetrically fixed on the multi-stage through the connecting flange (3). On the rotor boom, the GPS module is used to provide accurate GPS data to the controller during the path planning and flight stages; the vision module (8) and the millimeter-wave radar (13) are also symmetrically fixed on both sides of the multi-rotor boom, The support is fixed by the connecting flange and then extends downward; the vision module (8) estimates the motion information through the image and obtains a more accurate motion speed after being fused with the data of the accelerometer, and at the same time identifies the crop information during the operation of the system; The millimeter wave radar (13) is used together with the barometer to obtain the real-time height of the multi-rotor boom.

Further, the support rod (10) is formed by connecting a hollow tube and two tripods, which provides support and load-bearing functions for the entire spray rod structure, and the hollow structure of the support rod (10) also serves as the passage of liquid medicine and electric wires pipeline.

Further, the support rod (10) is a carbon fiber tube.

Further, the medicinal solution and battery box assembly (11) includes a battery, medicinal solution and control system hardware, and the battery provides power for the motor (2), the GPS module, the vision module (8), and the millimeter-wave radar (13); The control system hardware is used to implement navigation and path planning, and to perform precise estimation of position and attitude.

Further, the control system hardware includes a flight controller and an embedded processor, and the flight controller is respectively connected with a GPS module, a millimeter-wave radar (13), a multi-sensor redundancy module, and a plurality of ESCs for controlling the rotor; The flight controller is also connected with an embedded processor, and the embedded processor is connected with the vision module (8) and the solenoid valve driver at the same time, and the solenoid valve driver is connected with the solenoid valve for controlling the spray head (5). The multi-sensor redundancy The module integrates a magnetic compass, barometer and two sets of gyroscopes and accelerometers inside.

Further, when it is necessary to realize the lifting and yaw movement of the boom, by adjusting the installation angles of the auxiliary rotor, the main rotor and the adjusting rotor to the axial vertical setting, all the rotors provide upward lift, which can make the multi-rotor boom have the maximum lift;

When it is necessary to increase the lift of the boom and increase the load capacity, the main rotor adopts the upper and lower paddle layout, the auxiliary rotor adopts the axial horizontal setting, and the adjusting rotor adopts the axial angle to be set within the adjustment range of 0-90 degrees.

A control method of a multi-rotor spray rod structure of the present invention, the technical scheme comprises the following steps:

After the system is powered on, the initialization operation is performed first. First, the GPS information of the working area is collected through the GPS module, and the upcoming flight trajectory is planned by the path planning algorithm. The GPS module provides accurate positioning information for the multi-rotor boom during the flight. ; After the path planning is completed and the take-off command is received, the take-off procedure is executed. After take-off and before landing, the cascade PID controller controls the attitude, speed, height, etc. of the multi-rotor boom to make it follow the planned route. flight path;

After the take-off is successful, the image data returned by the vision module (8) is processed by the embedded processor. The image processing is divided into two threads: first, the motion information is obtained by the optical flow method, and it is more accurate after being fused with the IMU data. The movement speed of the multi-rotor boom is sent back to the flight controller; the second is to identify the presence or absence of crops and the dense information after image processing, so as to prepare for the subsequent precise variable spray;

Since the mist-like liquid is easily lost in the air, the multi-rotor boom should maintain a suitable altitude and stable flight during operation. The flight controller estimates the accurate Height value, control its own height to maintain a suitable working height;

After judging whether it is a standard working area, different operations will be performed according to the results. In the normal spraying process, the embedded processor drives the solenoid valve to control all nozzles to operate through the solenoid valve driver; in the corner area, the embedded processor operates according to the calculation results. Only some solenoid valves are controlled to work to realize variable spray.

Further, the specific process of controlling the attitude, speed, height, etc. of the multi-rotor boom by the cascade PID controller is as follows:

The cascade PID is used to control the posture and attitude of the unmanned boom. The angular velocity is used as the first inner loop, and the angular velocity is measured by the gyroscope; then the angle control is used as the second inner loop, and the angle is estimated by It is estimated by gyroscope and magnetic compass sensors; the third inner loop is the speed control loop, and the speed estimation is obtained by fusing image data and IMU data; the final outer loop is height control, and here we also fuse millimeter waves The data of sensors such as radar, barometer, and gyroscope are used to control the posture and movement of the rotor boom to realize the spray operation based on path planning.

The present invention has the following technical effects:

While taking into account the flexibility, speed and low cost of UAVs, this design also has the characteristics that conventional plant protection UAVs do not have:

1. Multiple pairs of nozzles are arranged in a line, which can spray a larger area per unit time, effectively improving the operation efficiency.

2. It can control multiple pairs of rotors to make them in different attitudes. When it works in the corner area of the farmland, it can control the rotors to make the yaw movement, and at the same time control its multiple nozzles with variables to achieve precise spraying and reduce the amount of liquid medicine. churn and waste.

3. Using carbon fiber material, the structure is simple and the weight is small. Under the same weight, more lift can be used to dispense more liquid or larger capacity batteries.

4. On the basis of the basic type, this design can adjust its load by means of paddle alignment and adjustment of the installation angle of the auxiliary rotor, which increases the flexibility of the design.

5. This design can be used as a basic unit. When needed, multiple basic units can be connected through quick joints to achieve larger area operations.

6. The connecting parts between the main lift rotor and the boom can use damped connectors, so that when the multi-rotor boom is working, even if it is occasionally affected by gusts, the attitude changes can be weakened by the damped connectors, increasing the stability of the equipment sex.

Description of drawings

Fig. 1 is the overall structure diagram of the multi-rotor boom;

Fig. 2 is the hardware structure diagram of the control system;

Figure 3 Cascade PID control diagram;

Fig. 4 is the structure diagram of PID controller;

Fig. 5 system control logic diagram;

6 is a schematic diagram of an optical flow method algorithm;

Figure 7 Multi-rotor boom deformation 1;

Figure 8 Multi-rotor boom deformation 2;

In the figure, 1-auxiliary rotor a; 2-motor; 3-connecting flange; 4-liquid pipe; 5-spray head; 6-adjusting rotor a; 7-GPS module a; 8-vision module; 9-main force Rotor a; 10- support rod; 11- liquid medicine and battery box assembly; 12- main rotor b; 13- millimeter wave radar; 14- GPS module b; 15- adjusting rotor b; 16- auxiliary rotor b;

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

As a specific embodiment of the present invention, as shown in the overall structure diagram of the boom as shown in Figure 1, it is mainly composed of the following parts: 1- auxiliary rotor a; 2- motor; 3- connecting flange; 4- liquid medicine Pipe; 5-Sprinkler; 6-Adjusting Rotor a; 7-GPS Module a; 8-Vision Module; 9-Main Rotor a; 10-Support Rod; 11-Medical Liquid and Battery Box Assembly; 12-Main Rotor B; - Millimeter wave radar; 14 - GPS module b; 15 - Regulating rotor b; 16 - Auxiliary rotor b; There are multiple rotors evenly distributed on the boom throughout the structure (1, 6, 9, 12, 15, 16) , their installation angles can be appropriately changed according to the application scenario, as shown in Figure 1, the

axes

1 and 16 are set horizontally, the axes 6 and 15 are set at 0-90 degrees, and the axes 9 and 12 are set vertically. Differences.

There are many pairs of rotors symmetrically distributed on the above-mentioned support rod 10, and the rotors include auxiliary rotors (auxiliary rotors a1, auxiliary rotors b16), adjustment rotors (adjustment rotors a6, adjustment rotors b15) and main force rotors (main force rotor a9, main force rotor b12), Among them, the main rotor provides most of the lift required for the boom to fly, and can be multiple as needed; the angle of the auxiliary rotor and the adjustment rotor can be adjusted, which can be multiple according to their respective needs, providing lift for the overall boom and countermeasures to the boom. At the same time, the downward airflow generated by it can accelerate the liquid medicine to adhere to the surface of crops.

The medicinal liquid and battery box assembly 11 are tightly fixed by bolts and the spray rod; the structural shape of the medicinal liquid and the battery box assembly is an upper triangle and a lower rectangular shape, and the shape of the medicinal liquid and the battery box is conducive to lowering the center of gravity of the entire multi-rotor spray rod , to increase its stability.

As shown in Figure 1, the GPS module (GPS module a7, GPS module b14) and the visual module detail diagram, the GPS module is composed of the GPS-RTK signal receiving module, which is firmly fixed by the connecting flange 3, the support rod and the tripod, because here Using RTK technology, there are two GPS modules distributed symmetrically. The vision module 8 is fixed with a bracket that is connected to the connecting flange and extends vertically downward, and its spatial position is symmetrically distributed with the millimeter wave radar 13 .

The liquid medicine and battery box are mainly divided into three parts inside the liquid medicine and battery box assembly 11, and their functions are mainly to accommodate the battery, control system hardware and store the liquid medicine.

Figure 2 shows the hardware structure diagram of the control system, including a flight controller and an embedded processor. The flight controller is connected to the GPS module, the millimeter-wave radar 13, the multi-sensor redundancy module, and multiple electrical circuits for controlling the rotor. The flight controller is also connected with the embedded processor, the embedded processor is connected with the vision module 8 and the solenoid valve driver at the same time, and the solenoid valve driver is connected with the solenoid valve controlling the nozzle 5, and the multi-sensor redundancy module A magnetic compass, barometer and two sets of gyroscopes and accelerometers are integrated internally, so that when one of the sensors fails, it can immediately switch to a backup sensor, increasing the stability and reliability of the system. The underlying driver includes ESC and solenoid valve driver; the actuator has multiple rotor motors and solenoid valves corresponding to the number of nozzles.

Figure 3 shows the cascade PID control diagram. Because in the engineering field, PID control is still the most widely used one in practical applications, and the common quadrotor flight control systems currently on the market also use PID control algorithms. This patent uses cascade PID to control the pose of the unmanned boom.

PID control is a general term for proportional control, integral control and differential control. In the process of practical application, in the face of different controlled objects, it is necessary to select methods that meet the requirements to make different combinations of P, I, and D controls to achieve the best control purpose. We usually combine these freely combined controls. The controller is collectively called a PID controller. The PID controller is essentially a second-order linear low-pass filter, which can effectively reduce the influence of disturbance and error on the output result. The following figure shows the structure of a traditional PID controller:

As shown in Figure 4, r(t) in the above figure is the input of the system at time t, y(t) is the output of the system at time t; e(t) as the deviation is the input of the regulator, which is t The difference between the input and output of the system at time is:

e(t)=y(t)-r(t) (1)

u(t) is the output of the regulator at time t, which is obtained by linearly summing the deviation e(t) after proportional, integral and differential calculations. Here the expression for the traditional PID controller is given as:

In the formula, T _i and T _d respectively represent the integral time constant and the differential time constant at time t, and let K _p /T _i =K _i , K _p *Td=K _d . Then the expression of the PID controller can be written as:

In the formula, K _p represents the proportional coefficient, K _i represents the integral coefficient, and K _d represents the differential coefficient. Its discretization formula can be expressed as:

In the actual use process, in order to optimize the performance of the PID control system, it is necessary to continuously adjust the three parameter values of proportional, integral and differential. The use of cascade PID controller to control the system can effectively reduce the influence of errors caused by external interference and improve the robustness of the system. The principle of cascade PID control is to control each other by multiple single-loop feedback controls.

As shown in Figure 3, we take the angular velocity as the first inner loop, and the angular velocity is measured by the gyroscope; then the angle control is taken as the second inner loop, and the angle is estimated by the gyroscope, magnetic compass and other sensors. ; The third inner loop is the speed control loop, and the speed estimation is obtained by fusing image data and IMU data; the final outer loop is altitude control, here we also fuse sensors such as millimeter wave radar, barometer, gyroscope, etc. data in order to obtain a more accurate height value. Through such a cascade PID controller, we can well control the pose and motion of the multi-rotor boom, and realize the spray operation based on path planning.

Figure 5 shows the system control flow chart. After the system is powered on, the initialization operation is performed first, and then the path planning is carried out according to the GPS data of the operation area collected in advance. After the path planning is completed and the take-off command is received, the take-off procedure is executed. After takeoff and before landing, the cascade PID controller controls the attitude, speed, height, etc. of the multi-rotor boom so that it can fly along the planned path. After the take-off is successful, the image data returned by the embedded processor to the vision module is divided into two threads: first, the motion information is obtained by the optical flow method, and it is fused with the IMU data to obtain a more accurate multi-rotor jet. The movement speed of the rod is sent back to the flight controller; the second is to identify the presence or absence of crops and the dense information after image processing, so as to prepare for the subsequent precise variable spray. Since the mist-like liquid is easily lost in the air, the multi-rotor boom should maintain a suitable altitude and stable flight during operation. Here, the flight controller estimates the accurate altitude through the data of sensors such as millimeter wave radar and barometer. value, control its own height to maintain a suitable working height. After judging whether it is a standard working area, different operations will be performed according to the results. In the normal spraying process, the processor controls all the nozzles to operate through the solenoid valve driver; in the corner area, the processor only controls some of the solenoid valves to work according to the calculation results to realize variable spraying.

The above-mentioned vision module 8 uses the optical flow method to detect the motion of objects in the field of view. For the optical flow method, the principle is as follows:

Optical flow is a way to describe the movement of pixels between images over time, as shown in Figure 6. Over time, the same pixel moves in an image, and we want to track its movement. The calculation of the motion of some pixels is called sparse optical flow, and the calculation of the motion of all pixels is called dense optical flow. We adopt the representative of sparse optical flow: LK (Lucas-Kanade) optical flow. Schematic diagram of the LK optical flow method In LK optical flow, we consider the image from the camera to be time-varying. The image can be seen as a function of time: I(t); then, at a time t at

The pixel at , its grayscale can be written as:

I(x,y,t). (5)

We regard the image as a function of position and time, and its range is the grayscale of the pixels in the image. Now consider a fixed point in space whose pixel coordinates at time t are x, y. Due to the movement of the camera, its image coordinates will change. Grayscale invariance assumption: The pixel grayscale value of the same spatial point is fixed in each image. For the pixel located at (x, y) at time t, we set it to move to (x+dx, y+dy) at t+dt. Since the gray level remains unchanged, we have:

I(x+dx,y+dy,t+dt)＝I(x,y,t) (6)

Perform Taylor expansion on the left side of the above equation and keep the first-order term, we get:

Thus there are:

Divide both sides by dt to get:

in

is the motion speed of the pixel on the x-axis, and

are the velocities on the y-axis, and denote them as u, v. Simultaneously

is the gradient of the image in the x direction at this point, and the other is the gradient in the y direction, denoted as I _x , I _y . Denote the variation of image gray level with time as I _t , and write it as a matrix, there are:

We want to get u,v, but since the formula is a linear equation with two variables, it cannot calculate u,v by itself. Therefore, we assume that the pixels within a certain window have the same motion.

consider a

, which contains ω ² pixels. Since the pixels within the window have the same motion, we have a total of ² equations for ω:

remember:

So the whole equation:

This overdetermined linear equation for u,v can be solved by the least squares method:

In this way, the motion speed u, v of the pixel between the images can be obtained.

The main function of the rotor is to provide lift and control the attitude of the boom. At the same time, the downward airflow generated by the rotor can accelerate the attachment of the liquid to the surface of the crop and reduce the loss of the liquid in the air; the connection between the rotor, the boom and the nozzle as follows:

As a specific embodiment of the present invention, FIG. 7 is a structural deformation diagram of a multi-rotor spray rod. When the lifting and yaw motion of the spray rod needs to be realized, the installation angles of the auxiliary rotor, the main rotor and the adjusting rotor are adjusted to the axis Towards a vertical setting, all rotors provide upward lift for maximum lift on the multi-rotor boom. At this time, the lower ends of the main rotor, the auxiliary rotor and the adjusting rotor are all connected with a motor 2 to provide power for the rotor. The motor 2 is connected with a connecting flange 3, and the lower end of the connecting flange 3 is a liquid medicine pipeline 4, and the connecting flange 3 is connected to the motor 2. The liquid medicine pipeline 4 is tightly fixed, and the liquid medicine pipeline 4 connects the nozzles 5 and provides the liquid medicine for the spray rod.

As another specific embodiment of the present invention, when it is necessary to achieve the lifting force of the boom (as shown in Figure 8) and increase the load capacity, the main rotor adopts the layout of the upper and lower paddles, the auxiliary rotor adopts the axial horizontal setting, and the adjustment rotor is used. The axial angle is set within the adjustment range of 0-90 degrees. When any one of the main rotor, auxiliary rotor and adjustment rotor adopts the layout of the upper and lower paddles (as shown in Figure 8), the nozzle corresponding to the lower end of the rotor is replaced with a rotor of the same model and opposite direction to provide greater lift for the boom ( At this time, the nozzle is not connected to the bottom of the paddle, and a motor is connected to the upper and lower paddles).

At this time, the auxiliary rotor a1 and the auxiliary rotor b16 are arranged axially horizontally, the adjustment rotor a6 and the adjustment rotor b15 are arranged at 0-90 degrees in the axial direction, and the main rotor a9 and the main rotor b12 are arranged in the vertical direction.

In the description of this specification, reference to the terms "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples", etc., is meant to incorporate the embodiments A particular feature, structure, material, or characteristic described by an example or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, The scope of the invention is defined by the claims and their equivalents.

Claims

A multi-rotor spray-rod structure, characterized in that it comprises a support rod (10), and the support rod (10) is provided with a rotor, a motor (2), a connection flange (3), a liquid medicine pipeline (4), nozzle (5), GPS module, vision module (8), liquid medicine and battery box assembly (11), millimeter wave radar (13);

There are a plurality of pairs of rotors symmetrically distributed on the support rod (10), and the rotors include auxiliary rotors, adjustment rotors and main rotors, wherein the main rotors provide most of the lift required for the boom to fly, and the auxiliary rotors and the adjustment rotors are adjustable in angle, Provide lift for the whole boom and control the posture of the boom, and at the same time, the downward airflow generated by it can accelerate the attachment of the medicinal liquid to the surface of the crops; the center of the support rod (10) is fixed with the medicinal liquid and the battery box assembly (11), Both ends of the support rod (10) are provided with auxiliary rotors, an adjustment rotor is provided between the auxiliary rotor and the tripod of the support rod (10), and the adjacent ends of the medicinal solution and the battery box assembly (11) are symmetrically provided with main force rotor;

When any one of the main rotor, auxiliary rotor and adjustment rotor adopts the layout of up and down paddle, the nozzle corresponding to the lower end of the rotor is replaced with a rotor of the same model and opposite direction to provide greater lift for the boom;

When the main rotor, the auxiliary rotor and the regulating rotor do not adopt the layout of the upper and lower paddles, the lower ends are connected with a motor (2) to provide power for the rotor, and the motor (2) is connected with a connecting flange (3), and the connecting flange ( 3) The lower end is the liquid medicine pipe (4), the connecting flange (3) tightly fixes the motor (2) and the liquid medicine pipe (4), and the liquid medicine pipe (4) connects the nozzles (5) and provides the spray rod. liquid medicine;

The GPS module is tightly and symmetrically fixed on the multi-rotor boom through the connecting flange (3), and the GPS module is used to provide accurate GPS data to the controller in the path planning and flight stages; the vision module (8) is connected with the millimeter wave. The radar (13) is also symmetrically fixed on both sides of the multi-rotor boom, and is fixed by the bracket through the connecting flange and then extends downward; the vision module (8) estimates the motion information through the image and combines with the accelerometer to obtain the motion speed, At the same time, the crop information is identified during the operation of the system; the millimeter wave radar (13) is used together with the barometer to obtain the real-time height of the multi-rotor boom.
A multi-rotor boom structure according to claim 1, characterized in that the support rod (10) is formed by connecting a hollow tube and two tripods, which provides support and load-bearing functions for the entire boom structure , the hollow structure of the support rod (10) also serves as a passage channel for the liquid medicine and electric wires.
The multi-rotor boom structure according to claim 2, wherein the support rod (10) is a carbon fiber tube.
A multi-rotor boom structure according to claim 1, characterized in that the liquid medicine and battery box assembly (11) comprises a battery, liquid medicine and control system hardware, and the battery is a motor (2), a GPS The module, the vision module (8), and the millimeter wave radar (13) provide power; the control system hardware is used to implement navigation and path planning, and to perform precise estimation of position and attitude.
The multi-rotor boom structure according to claim 4, wherein the control system hardware comprises a flight controller and an embedded processor, and the flight controller is respectively connected with a GPS module, a millimeter wave radar (13), a multi- The sensor redundancy module and the plurality of ESCs for controlling the rotor are connected; the flight controller is also connected with the embedded processor, and the embedded processor is connected with the vision module (8) and the solenoid valve driver at the same time, and the solenoid valve driver Connected to the solenoid valve for controlling the spray head (5), the multi-sensor redundancy module internally integrates a magnetic compass, a barometer, and two sets of gyroscopes and accelerometers.
A multi-rotor boom structure according to claim 1, wherein,

When it is necessary to realize the lifting and yaw motion of the boom, by adjusting the installation angles of the auxiliary rotor, the main rotor and the adjusting rotor to the axial vertical setting, all the rotors provide upward lift, which can make the multi-rotor boom have the maximum lift. ;

When it is necessary to increase the lift of the boom and increase the load capacity, the main rotor adopts the upper and lower paddle layout, the auxiliary rotor adopts the axial horizontal setting, and the adjusting rotor adopts the axial angle to be set within the adjustment range of 0-90 degrees.
A kind of control method of multi-rotor boom structure according to claim 1, is characterized in that, comprises the following steps:

After the system is powered on, the initialization operation is performed first. First, the GPS information of the working area is collected through the GPS module, and the upcoming flight trajectory is planned by the path planning algorithm. The GPS module provides accurate positioning information for the multi-rotor boom during the flight. ; After the path planning is completed and the take-off command is received, the take-off procedure is executed. After take-off and before landing, the cascade PID controller controls the attitude, speed, height, etc. of the multi-rotor boom to make it follow the planned route. flight path;

After the take-off is successful, the image data returned by the vision module (8) is processed by the embedded processor. The image processing is divided into two threads: first, the motion information is obtained by the optical flow method, and it is more accurate after being fused with the IMU data. The movement speed of the multi-rotor boom is sent back to the flight controller; the second is to identify the presence or absence of crops and the dense information after image processing, so as to prepare for the subsequent precise variable spray;

Since the mist-like liquid is easily lost in the air, the multi-rotor boom should maintain a suitable altitude and stable flight during operation. The flight controller estimates the accurate Height value, control its own height to maintain a suitable working height;

After judging whether it is a standard working area, different operations will be carried out according to the results. In the normal spraying process, the embedded processor drives the solenoid valve through the solenoid valve driver to control all nozzles to operate; in the corner area, the embedded processor operates according to the calculation results. Only some solenoid valves are controlled to work to realize variable spray.
The control method of a kind of multi-rotor boom structure according to claim 7, is characterized in that, the concrete process that the attitude, speed, height etc. of multi-rotor boom are controlled by cascade PID controller is:

The cascade PID is used to control the posture and attitude of the unmanned boom. The angular velocity is used as the first inner loop, and the angular velocity is measured by the gyroscope; then the angle control is used as the second inner loop, and the angle is estimated by It is estimated by gyroscope and magnetic compass sensor; the third inner loop is the speed control loop, and the speed estimation is obtained by fusing image data and IMU data; the final outer loop is height control, here we also fuse millimeter waves Data from sensors such as radar, barometer, and gyroscope are used to control the posture and movement of the rotor boom to realize spray operations based on path planning.