CN110825100A - Plant protection fixed wing unmanned aerial vehicle autonomous take-off and landing control method - Google Patents

Abstract

This invention discloses an autonomous takeoff and landing control method for a plant protection fixed-wing drone, comprising a drone flight control system, a drone ground control station, a flight parameter acquisition module, an image acquisition and processing module, a flight attitude control module, a spraying control module, and a power supply module. When performing multiple consecutive flight spraying operations, the drone can autonomously take off and land between waypoints, thereby avoiding repetition of spraying routes and waste of sprayed pesticides, and improving the efficiency of multi-flight plant protection drone spraying operations.

Description

An autonomous take-off and landing control method for a plant-protected fixed-wing unmanned aerial vehicle

【Technical field】

The invention relates to an autonomous take-off and landing control method for a plant protection fixed-wing unmanned aerial vehicle, belonging to the technical field of agricultural plant protection unmanned aerial vehicles.

【Background technique】

Since the beginning of the new century, the concept of efficient agriculture and precision agriculture has gradually gained popularity, and plant protection drones have also received more and more attention. With the continuous improvement and promotion of related technologies, agricultural plant protection drones featuring high efficiency and convenience will gradually change the traditional mode of relying on manual operations in the agricultural field, and become the main means and backbone of agricultural monitoring and agricultural plant protection.

With the gradual maturity of plant protection drone technology, more and more countries have applied it to actual production operations. For example, in countries dominated by livestock such as Australia and Brazil, agricultural drones are mostly used to monitor grassland growth, herd positioning, and to obtain timely information on pests and diseases. South Korea also began to introduce drones for aerial plant protection operations in early 2003, and the number of agricultural drones and the area of drone operations in South Korea are increasing year by year.

In the early 1950s, my country had carried out research on aviation plant protection aircraft and spraying technology, but at that time, due to the relatively weak domestic aviation plant protection technology, operating aircraft and equipment were basically purchased from abroad. It was not until 1958 that Nanchang Aircraft Factory produced the first agricultural aircraft "Y-5", thus breaking the foreign monopoly on aviation plant protection technology.

Unmanned plant protection technology has attracted widespread attention because of its speed and efficiency. However, due to the large operating area, it is difficult for a single UAV to carry enough weight of liquid medicine. Therefore, the continuous flight operation of multiple UAVs must be solved. The technical problem, how to provide a relatively fast autonomous take-off and landing technology between multiple sorties is the technical problem to be solved by the present invention. (It is suggested that the applicant add this advantage to the description or the claims to highlight the beneficial effects of the invention of the present application. The spraying planning in the prior art is to determine the waypoints midway through GPS positioning only after the dose is almost used up.

[Content of the invention]

In order to solve the problem of autonomous take-off and landing faced by the continuous operation of plant protection UAVs during multiple flight sorties, reduce energy consumption and avoid repeated spraying. In addition, the pre-spraying planning method based on the image collection of the UAV of the present invention can judge the relationship between the area of the area to be operated and the capacity of the spraying box through the collected image information in advance, so as to obtain the midway change point for spraying in advance. To implement planning so that multiple UAVs can work at the same time, the present invention designs the following technical solutions.

A plant-protected fixed-wing unmanned autonomous take-off and landing control method, comprising multiple sorties of unmanned aerial vehicles, an unmanned aerial vehicle flight control system, an unmanned aerial vehicle ground control station, a flight parameter acquisition module, an image acquisition and processing module, a flight attitude control module, The spraying control module and the power supply module; the trajectory planning control method is as follows:

Step 1: The UAV and the ground control station are powered on for self-inspection, the ground control station sends control commands, initializes the flight control system, initializes the spraying control module, and initializes the image acquisition and processing module;

Step 2: Enter the automatic cruise process, start the image acquisition and processing module, obtain the vegetation image of the to-be-operated area through the high-definition camera, and obtain the vegetation image data after the image processing algorithm;

Step 3: Calculate the above vegetation image data to determine the relationship between the area of the area to be operated and the capacity of the spraying box. If the capacity of the spraying box is not enough to complete the spraying in the working area, execute the multi-vehicle area track planning and enter the step 4. Otherwise, execute the regional track planning for a single sortie, and go to step 7;

Step 4: Enter the liquid medicine replenishment and midway return point calculation, determine the midway connection and change point of the multi-sort UAV, and carry out the optimization calculation of the spray quantity and return point of each sortie;

Step 5: The drone enters the autonomous take-off control process and is ready to perform spraying operations;

Step 6: When the liquid volume of the medicine box of the drone is lower than the first threshold L1 of the capacity, the drone is notified to return and land, enter the autonomous landing control process, and the next drone will continue to fly, repeat the above step 5 until it is completed All spray work areas.

Step 7: Read the vegetation image data cached by the image acquisition and processing module, and calculate the variable spraying control signal according to the empirical function; drive the solenoid valve, start the spraying operation, and read the data of the liquid level sensor of the spraying box in real time to judge the spraying. When the liquid volume is lower than the first threshold L1 of the volume, the drone will be notified to return;

Further, in the step 5, the autonomous take-off control process of the UAV is as follows: set the take-off height, set the take-off height according to the flight height during the last cruise operation, obtain the current position coordinate point through GIS, and set the current position coordinate point. The position point is used as the return point, the continuous waypoint is used as the target waypoint, the drone takes off automatically, and the flight control system controls the attitude of the plant protection drone, so that the plant protection drone flies straight to the target waypoint at a constant speed.

Further, in the step 6, the autonomous landing control process is as follows. When the drone is notified to return, the flight control system reads the pre-stored return point, takes the origin of the entire operation area as the target waypoint, and the plant protection drone keeps The current altitude is first moved above the home point position, and then the flight control system adjusts the flight speed of the plant protection drone according to the real-time altitude information collected, and decelerates to land at the target waypoint.

Further, in step 3, after obtaining the image of the spraying operation area, the image acquisition and processing module first performs the image grayscale binarization processing, and obtains the spatial proximity and pixel value similarity of the image based on the spatial distribution of the image, Combined with image grayscale similarity, the background denoising is realized, and the contour image of vegetation is obtained. In addition, the contour database of the vegetation area to be operated is pre-stored in the memory of the image processing system, and the image vegetation contour obtained after collection and processing is compared with the vegetation contour in the memory database to obtain the corresponding vegetation prior type matching value. , and transmit the matching value to the flight control system.

Further, in the step 4, when carrying out the continuous operation of multiple sorties of UAVs, first calculate the total length of the operation route F, the maximum route length Fm of a single sortie operation, and when F is an integer multiple of Fm, no further operations are performed. Route planning, according to the UAV to return to home when the liquid medicine is exhausted, and start another UAV to continue flying; when F is not an integer multiple of Fm, at least one halfway return is performed, and the minimum energy consumption for return is optimal. Solve, and use the coordinates of this point as the home point.

Further, the applicant of the present invention has obtained the numerical function relationship between the spraying control variable P and the area data S of the operation area, the vegetation type V, the number of vegetation rows R, and the number of vegetation columns C after many explorations and experiments. ,in

其中ω是PWM电路工作周期，θ是晶闸管导通角。

Where ω is the duty cycle of the PWM circuit, and θ is the conduction angle of the thyristor.

The UAV flight control system is responsible for data transmission and flight data processing with the ground station, and accepts manual control instructions from the ground control station.

The flight parameter acquisition module is used to acquire UAV flight state parameters, including flight height and flight speed.

The image acquisition and processing module is used for image acquisition of the ground spraying operation area, and obtains image data of vegetation to be sprayed based on an image processing algorithm.

The spraying control module is used to comprehensively execute spraying flow control according to the image data collected by the image collection and processing module and the flight control state parameters of the UAV, so as to ensure that the UAV realizes the control of the spraying flow according to the type of ground vegetation and the current flight. Parameters such as status dynamically adjust the spray amount.

The ground control station and the UAV flight control system perform remote data transmission, so that the flight control system can accept the control data of the ground staff, thereby realizing the remote control of the UAV.

The power supply module provides corresponding power supply for each of the above modules.

Further, the image acquisition and processing module is a high-definition remote sensing camera, which captures images of the ground spraying operation area through remote sensing, and obtains the area of the spraying operation area, the type of vegetation, the number of vegetation rows, the vegetation column based on the image processing algorithm. data and transmit this data to the UAV flight control system.

Further, the flight parameter acquisition module is a strapdown inertial navigation system based on GPS/INS, which can accurately acquire the flight altitude and flight speed of the UAV in real time.

Further, the power module is a large-capacity, rechargeable, and long-lasting lithium battery pack.

Further, the UAV ground control station performs remote data transmission with the UAV flight control system through a wireless communication network, such as WIFI or 4G.

Further, the first threshold value L1 of the capacity is 0.5 liters.

Optionally, the spray box has a capacity of about 5L-10L, and is mounted directly below the unmanned aerial vehicle and directly above the diaphragm pump. The water outlet is connected to the water inlet of the diaphragm pump; the diaphragm pump is used to provide liquid medicine. Apply pressure. The PWM control module adopts a MOSFET trigger switch driving module for converting the PWM duty cycle signal into a diaphragm pump driving voltage signal. The solenoid valve is used to control the opening and closing of the spraying of the nozzle. There is a liquid level sensor on the top of the spray box, which can obtain the liquid volume data inside the spray box in real time.

【Description of drawings】

1 is a flowchart of the autonomous take-off and landing control algorithm of the plant protection UAV of the present invention.

【Detailed ways】

In order to solve the problem of autonomous take-off and landing faced by the continuous operation of the plant protection fixed-wing UAV during the multi-sort flight process, reduce energy consumption, and avoid repeated spraying, the present invention designs the following technical solutions.

A plant-protected fixed-wing unmanned autonomous take-off and landing control method, comprising multiple sorties of unmanned aerial vehicles, an unmanned aerial vehicle flight control system, an unmanned aerial vehicle ground control station, a flight parameter acquisition module, an image acquisition and processing module, a flight attitude control module, The spraying control module and the power supply module; the trajectory planning control method is as follows:

Step 1: The UAV and the ground control station are powered on for self-inspection, the ground control station sends control commands, initializes the flight control system, initializes the spraying control module, and initializes the image acquisition and processing module;

Step 2: Enter the automatic cruise process, start the image acquisition and processing module, obtain the vegetation image of the to-be-operated area through the high-definition camera, and obtain the vegetation image data after the image processing algorithm;

Step 3: Calculate the above vegetation image data to determine the relationship between the area of the area to be operated and the capacity of the spraying box. If the capacity of the spraying box is not enough to complete the spraying in the working area, execute the multi-vehicle area track planning and enter the step 4. Otherwise, execute the regional track planning for a single sortie, and go to step 7;

Step 4: Enter the liquid medicine replenishment and midway return point calculation, determine the midway connection and change point of the multi-sort UAV, and carry out the optimization calculation of the spray quantity and return point of each sortie;

Step 5: The drone enters the autonomous take-off control process and is ready to perform spraying operations;

Step 6: When the liquid volume of the medicine box of the drone is lower than the first threshold L1 of the capacity, the drone is notified to return and land, enter the autonomous landing control process, and the next drone will continue to fly, repeat the above step 5 until it is completed All spray work areas.

Step 7: Read the vegetation image data cached by the image acquisition and processing module, and calculate the variable spraying control signal according to the empirical function; drive the solenoid valve, start the spraying operation, and read the data of the liquid level sensor of the spraying box in real time to judge the spraying. When the liquid volume is lower than the first threshold L1 of the volume, the drone will be notified to return;

Further, in the step 5, the autonomous take-off control process of the UAV is as follows: set the take-off height, set the take-off height according to the flight height during the last cruise operation, obtain the current position coordinate point through GIS, and set the current position coordinate point. The position point is used as the return point, the continuous waypoint is used as the target waypoint, the drone takes off automatically, and the flight control system controls the attitude of the plant protection drone, so that the plant protection drone flies straight to the target waypoint at a constant speed.

Further, in the step 6, the autonomous landing control process is as follows. When the drone is notified to return, the flight control system reads the pre-stored return point, takes the origin of the entire operation area as the target waypoint, and the plant protection drone keeps The current altitude is first moved above the home point position, and then the flight control system adjusts the flight speed of the plant protection drone according to the real-time altitude information collected, and decelerates to land at the target waypoint.

Further, in step 3, after obtaining the image of the spraying operation area, the image acquisition and processing module first performs the image grayscale binarization processing, and obtains the spatial proximity and pixel value similarity of the image based on the spatial distribution of the image, Combined with the similarity of image grayscale, the background denoising is realized, and the contour image of vegetation is obtained. In addition, the contour database of the vegetation area to be operated is pre-stored in the memory of the image processing system, and the image vegetation contour obtained after collection and processing is compared with the vegetation contour in the memory database to obtain the corresponding vegetation prior type matching value. , and transmit the matching value to the flight control system.

Further, in the step 4, when carrying out the continuous operation of multiple sorties of UAVs, first calculate the total length of the operation route F, the maximum route length Fm of a single sortie operation, and when F is an integer multiple of Fm, no further operations are performed. Route planning, according to the UAV to return to home when the liquid medicine is exhausted, and start another UAV to continue flying; when F is not an integer multiple of Fm, at least one halfway return is performed, and the minimum energy consumption for return is optimal. Solve, and use the coordinates of this point as the home point.

Further, the applicant of the present invention has obtained the numerical function relationship between the spraying control variable P and the area data S of the operation area, the vegetation type V, the number of vegetation rows R, and the number of vegetation columns C after many explorations and experiments. ,in

其中ω是PWM电路工作周期，θ是晶闸管导通角。

Where ω is the duty cycle of the PWM circuit, and θ is the conduction angle of the thyristor.

The UAV flight control system is responsible for data transmission and flight data processing with the ground station, and accepts manual control instructions from the ground control station.

The flight parameter acquisition module is used to acquire UAV flight state parameters, including flight height and flight speed.

The image acquisition and processing module is used for image acquisition of the ground spraying operation area, and obtains image data of vegetation to be sprayed based on an image processing algorithm.

The spraying control module is used to comprehensively execute spraying flow control according to the image data collected by the image collection and processing module and the flight control state parameters of the UAV, so as to ensure that the UAV realizes the control of the spraying flow according to the type of ground vegetation and the current flight. Parameters such as status dynamically adjust the spray amount.

The ground control station and the UAV flight control system perform remote data transmission, so that the flight control system can accept the control data of the ground staff, thereby realizing the remote control of the UAV.

The power supply module provides corresponding power supply for each of the above modules.

Further, the image acquisition and processing module is a high-definition remote sensing camera, which captures images of the ground spraying operation area through remote sensing, and obtains the area of the spraying operation area, the type of vegetation, the number of vegetation rows, the vegetation column based on the image processing algorithm. data and transmit this data to the UAV flight control system.

Further, the flight parameter acquisition module is a strapdown inertial navigation system based on GPS/INS, which can accurately acquire the flight altitude and flight speed of the UAV in real time.

Further, the power module is a large-capacity, rechargeable, and long-lasting lithium battery pack.

Further, the UAV ground control station performs remote data transmission with the UAV flight control system through a wireless communication network, such as WIFI or 4G.

Further, the first threshold value L1 of the capacity is 0.5 liters.

Optionally, the spray box has a capacity of about 5L-10L, and is mounted directly below the unmanned aerial vehicle and directly above the diaphragm pump. The water outlet is connected to the water inlet of the diaphragm pump; the diaphragm pump is used to provide liquid medicine. Apply pressure. The PWM control module adopts a MOSFET trigger switch driving module for converting the PWM duty cycle signal into a diaphragm pump driving voltage signal. The solenoid valve is used to control the opening and closing of the spraying of the nozzle. There is a liquid level sensor on the top of the spray box, which can obtain real-time data of the liquid volume inside the spray box.

In the selection of the empirical formula for the variables of vegetation spraying, the inventor subtracts one from the number of rows and columns of vegetation, and divides them by the area area, so that the working area of each grid area can be obtained, and then, using the preset The vegetation type value, as the adjustment coefficient of spraying control, uses the basic mathematical relationship to obtain the input waveform of the PWM signal control. Based on the basic knowledge of power electronics, the corresponding control signal can be obtained. Based on the variable precise spraying operation realized by the invention, the vegetation types can be well identified, and the waste of the medicinal solution in the spraying process can be avoided.

In order to verify the stability of the automatic cruise operation of the automatic plant protection UAV, two different sites were selected for group experiments. The number of test flights for each group was 50, and a total of 100 flight experiments were carried out.

For example, we choose the volume of the medicine box to be 5L, the diaphragm pump adopts PLD-1206, the rated voltage is 12V, the maximum pressure is 1MPa, and the maximum flow rate is 4L/min; the STM32F407VET6 microcontroller based on the ARM Cortex-M4 core is used as the core processor of the application controller; Assemble the various modules of the UAV and connect the data communication interface. After the UAV passes the image acquisition and data processing, the parameter state is judged by the spraying control module, and the calculation formula of the empirical function of the spraying control variable is calculated. After the PWM chopper control signal, the PWM controller is driven to realize the variable spraying operation.

When the plant protection drone flies to waypoint 2, the ground management system displays "The plant protection drone will return at the third waypoint". When the plant protection drone moves to the third waypoint, the plant protection drone interrupts the operation and executes the return home command, and then stores the relevant breakpoint information in the memory in the form of a text file. Finally, the plant protection drone flies to the landing site and lands on its own. .

Claims (8)

1. A plant protection fixed wing unmanned autonomous take-off and landing control method is characterized by comprising a plurality of unmanned aerial vehicles, an unmanned aerial vehicle flight control system, an unmanned aerial vehicle ground control station, a flight parameter acquisition module, an image acquisition and processing module, a flight attitude control module, a spraying control module and a power supply module; the autonomous take-off and landing control method specifically comprises the following steps:

step 1: the method comprises the following steps that power-on self-checking is carried out on an unmanned aerial vehicle and a ground control station, the ground control station sends a control command to carry out initialization of a flight control system, a spraying control module is initialized, and an image acquisition and processing module is initialized;

step 2: entering an automatic cruise process, starting an image acquisition and processing module, acquiring vegetation images of the to-be-operated area through a high-definition camera, and obtaining vegetation image data after an image processing algorithm;

and step 3: calculating the vegetation image data, judging the relation between the area of the area to be operated and the liquid medicine capacity of the spraying box, if the capacity of the spraying box is not enough to finish the spraying of the operation area, executing multi-frame spraying operation, and entering the step 4, otherwise executing single-frame area spraying operation, and entering the step 7;

and 4, step 4: performing liquid medicine supplement and midway return point calculation, determining midway continuing change points of the unmanned aerial vehicle for multiple frames, and performing optimized calculation on the medicine spraying amount and the return point of each frame;

and 5: the unmanned aerial vehicle enters an autonomous takeoff control flow to prepare for executing spraying operation;

step 6: when the liquid medicine capacity of the unmanned aerial vehicle pesticide spraying box is lower than the first volume threshold value L1, the unmanned aerial vehicle is informed to return to the air and land, an autonomous landing control flow is entered, the next unmanned aerial vehicle continuously flies, and the step 5 is repeated until all spraying operation areas are completed.

And 7: reading vegetation image data cached by the image acquisition and processing module, and calculating a variable spraying control signal according to an empirical function; the drive solenoid valve opens the spraying operation to read spraying case level sensor data in real time, judge the liquid medicine capacity, when the liquid medicine capacity is less than the first threshold value L1 of capacity, inform unmanned aerial vehicle to return voyage.

2. The plant protection fixed wing unmanned autonomous take-off and landing control method according to claim 1, characterized in that: in the step 2, the vegetation image data obtained in the step 2 specifically includes operation area data S, vegetation type V, vegetation line number R, and vegetation column number C.

3. The plant protection fixed wing unmanned autonomous take-off and landing control method according to claim 1, characterized in that: in step 3, after obtaining the image of the spraying operation area, the image acquisition and processing module firstly performs image gray level binarization processing, obtains spatial proximity and pixel value similarity of the image based on spatial distribution of the image, and implements background denoising by combining the image gray level similarity to obtain a contour image of the vegetation.

4. The plant protection fixed wing unmanned autonomous take-off and landing control method according to claim 1, characterized in that: in the step 4, when the continuous operation of multiple unmanned aerial vehicles is carried out, the total length F of an operation route and the maximum route length Fm of single operation are calculated firstly, when the F is integral multiple of the Fm, route planning is not carried out any more, return voyage is executed according to the situation that the unmanned aerial vehicles run out of liquid medicine, and meanwhile, the other unmanned aerial vehicle is started to continuously fly; and when F is not an integral multiple of Fm, performing at least one midway return voyage, performing optimal solution on the minimum point of return voyage energy consumption, and taking the point coordinate as a return voyage point.

5. The plant protection fixed wing unmanned autonomous take-off and landing control method according to claim 1, characterized in that: in the step 5, the unmanned aerial vehicle autonomous takeoff control process comprises the steps of setting a takeoff height, setting the takeoff height according to the flight height during the last cruise operation, acquiring a coordinate point of the current position through a GIS (geographic information system), taking the current position point as a return flight point, continuously changing the flight point as a target flight point, enabling the unmanned aerial vehicle to take off automatically, and controlling the posture of the plant protection unmanned aerial vehicle by a flight control system to enable the plant protection unmanned aerial vehicle to fly to the target flight point at a constant speed in a straight line.

6. The plant protection fixed wing unmanned autonomous take-off and landing control method according to claim 1, characterized in that: in step 6, the autonomous landing control process includes that when the unmanned aerial vehicle is notified to return to the flight, the flight control system reads a pre-stored return point, the original point of the whole operation area is used as a target flight point, the plant protection unmanned aerial vehicle keeps the current height and moves to the position above the return point, and then the flight control system regulates and controls the flight speed of the plant protection unmanned aerial vehicle according to the collected real-time height information and decelerates to land to the target flight point.

7. The plant protection unmanned self take-off and landing control method as claimed in claim 2, wherein: in the step 7, the spraying control signal P is in numerical function relationship with the operation area data S, the vegetation type V, the vegetation line number R and the vegetation line number C, wherein

Where ω is the PWM circuit duty cycle and θ is the thyristor conduction angle.

8. The plant protection unmanned aerial vehicle autonomous take-off and landing control method of claim 1, wherein the capacity first threshold value L1 is 0.5 liter.