CN111596652A

CN111596652A - Pesticide spraying intelligent agricultural machinery path finding navigation control method and system

Info

Publication number: CN111596652A
Application number: CN201911398815.9A
Authority: CN
Inventors: 张东; 姜茹; 李倩; 王恒玉; 王学林; 单铁成; 魏会心; 杨吉卿
Original assignee: Institute of Automation Shandong Academy of Sciences
Current assignee: Institute of Automation Shandong Academy of Sciences
Priority date: 2019-12-30
Filing date: 2019-12-30
Publication date: 2020-08-28

Abstract

The invention belongs to the technical field of intelligent agriculture, and discloses a pesticide spraying intelligent agricultural machinery path finding navigation control method and system, which are used for setting an operation task, selecting a working mode and determining the start and the end of the operation task; carrying out accurate navigation positioning on the agricultural machine by utilizing a GPS navigation and carrier phase difference technology, namely RTK (real-time kinematic) to acquire navigation positioning information of the agricultural machine; acquiring the state of an actuator and the information of the running state of an agricultural machine by using a vehicle-mounted controller; automatically planning a driving path according to the positioning result, the related driving data and the operation task; calculating a control target of the vehicle-mounted controller according to the current state of the agricultural machine and the planned path, and sending the control target to the vehicle-mounted controller; and the vehicle-mounted controller completes real-time control on the agricultural machine according to the reference control target and the agricultural machine state information. The invention realizes the path tracking precision within 2cm at the speed of 5km/h by a difference algorithm, has high positioning precision and small damage to crops.

Description

Pesticide spraying intelligent agricultural machinery path finding navigation control method and system

Technical Field

The invention belongs to the technical field of intelligent agriculture, and particularly relates to a pesticide spraying intelligent agricultural machinery path finding navigation control method and system.

Background

The intelligent level of agricultural machinery equipment is improved by applying modern information technology, and the method is an important means for implementing intelligent agriculture of China, realizing agricultural machinery and agriculture technology fusion and improving the development quality and benefit of agriculture. In recent years, beneficial exploration is conducted around the application of the Internet of things, big data, intelligent control and satellite navigation positioning to agricultural equipment and agricultural operation in various regions of China, and a plurality of successful cases are developed in the aspects of accurate operation of fields, intelligent management of facility agriculture and the like.

The unmanned technology integrates a plurality of technologies such as automatic control, a system structure, artificial intelligence, visual calculation and the like, is a product of high development of computer science, mode recognition and intelligent control technology, is an important mark for measuring national research strength and industrial level, and has wide application prospect in the fields of national defense and national economy.

At present, the technical level of agricultural machinery in China is entirely lagged behind, and although unmanned driving and navigation technologies are applied to agricultural machinery equipment in the prior art, automatic path planning cannot be realized, and the control precision error is large, so that automatic steering cannot be realized.

In summary, the problems of the prior art are as follows: (1) the existing agricultural machinery navigation and automatic driving technology cannot realize automatic path planning, has large control precision error and cannot realize automatic steering.

(2) Existing agricultural machinery is often limited to coverage of straight paths for autonomous driving.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides an intelligent agricultural machinery path-finding navigation control method and system for pesticide spraying.

The invention is realized in this way, a pesticide sprays the navigation control method of seeking way of the intellectual agricultural machinery, the said pesticide sprays the navigation control method of seeking way of the intellectual agricultural machinery and includes:

step one, setting a job task, selecting a working mode, and determining the start and the end of the job task;

secondly, carrying out accurate navigation positioning on the agricultural machine by utilizing a GPS navigation and carrier phase differential technology, namely RTK (real-time kinematic), and acquiring navigation positioning information of the agricultural machine; acquiring the state of an actuator and the information of the running state of an agricultural machine by using a vehicle-mounted controller;

step three, automatically planning a driving path according to the positioning result, the related driving data and the operation task;

step four, calculating a control target of the vehicle-mounted controller according to the current state of the agricultural machine and the planned path, and sending the control target to the vehicle-mounted controller;

and step five, the vehicle-mounted controller completes real-time control on the agricultural machinery according to the reference control target and the agricultural machinery state information.

Further, in the second step, the agricultural machinery navigation positioning information includes, but is not limited to, longitude and latitude, UTC time, ground speed, ground heading, roll angle, pitch angle, and positioning accuracy of the agricultural machinery position.

Further, in the second step, the method for accurately navigating and positioning the agricultural machinery comprises:

receiving BDS information, performing filtering processing on longitude and latitude information through a Kalman filtering algorithm, acquiring data of a visual sensor, and performing fusion processing on the received data of the BDS information and the latitude and longitude information; displaying a plot boundary on a screen through position and attitude information data received by a BDS receiver and other sensors, and planning a reasonable operation path according to plot conditions, operation requirements and the like; when the agricultural machine works, the working condition is displayed in real time through the dynamic tracking data of the BDS and the multi-sensor, and the vehicle-mounted automatic navigation of the agricultural machine is realized through the navigation technology.

Further, in step three, the path planning method includes:

modeling a farmland environment by a grid method, and then planning a path of a farmland subregion by adopting a linear-circular arc operation path algorithm;

(1) establishing a farmland environment model by adopting a grid method:

firstly, a farmland area is represented by grids, the grids without obstacles are called barrier-free grids, the grids with obstacles are called barrier grids, and the size of each unit grid is determined according to the motion state of the agricultural machinery; obtaining position information of beacon nodes in a farmland through an RTK-GPS; determining the basic shape of the farmland through the position coordinates of the beacon nodes arranged on the farmland corners and the boundaries, and determining the position coordinates of the obstacles in a plane coordinate system of the farmland according to the relative positions of the obstacles in the farmland and the farmland corners and the boundaries; obtaining a farmland grid map;

secondly, representing each grid in the farmland grid map by using a rectangular coordinate method and a serial number method;

the rectangular coordinate method comprises the following steps: the number of grids in each row and each column is 40, the farmland forms a grid matrix by 40 multiplied by 40 grids, and each grid is represented by the coordinates of the center point of the grid;

the sequence number method: all grids are numbered decimal from left to right and from bottom to top.

The rectangular coordinate codes and the serial number codes of the grids are in one-to-one correspondence;

(2) analyzing a straight line-arc operation path: selecting three sections of circular arcs as turning paths under the condition that d is less than or equal to 2 r; the turning path of the three arcs is formed by smoothly connecting the three arcs, and the radius of the three arcs is the same as the circle center;

(3) planning a straight line-arc operation path: generating a target path for agricultural machinery operation by combining a straight line and an arc line;

generating a target path according to the operation starting and stopping point position, the operation width, the operation path length and the direction related information input by the user;

obtaining the minimum turning radius and the operation width information of the agricultural machinery, and selecting a turning path generation strategy according to the size relationship:

the operation width is the distance between two adjacent straight paths in the operation process of the agricultural machine, under the condition that the operation width is smaller than the turning diameter, the agricultural machine turns according to a three-section circular arc path, at the moment, the agricultural machine needs to be adjusted in the opposite direction of the next operation straight line firstly, then turns, and completes the agricultural machine operation path according to the turning strategy;

if the operation width is larger than the width between the turns, the agricultural machine turns according to the arch-shaped path without the adjustment, and the agricultural machine operation path is completed according to the turning strategy.

Further, the intelligent pesticide spraying agricultural machinery path finding navigation control method further comprises the following steps:

the automatic driving of the agricultural machinery is started by a built-in timer, and in each timing interruption, path planning or real-time tracking is selected to be executed according to the requirement and the current state of the agricultural machinery;

when a task starts or under the condition of finishing a planned path, path planning can be carried out according to the requirement, otherwise, the agricultural machinery executes a control program of real-time tracking;

when path planning is executed, planning an optimal path for the agricultural machinery to enter a target path according to the current position, speed, driving direction related information of the agricultural machinery and the information of the target path;

when the real-time control is executed, according to the running deviation of the agricultural machine, the target steering angle and speed related control reference quantity of the agricultural machine are calculated in real time according to the planned automatic running path and the current running state of the agricultural machine and are used as the input of a vehicle-mounted control system to control the steering wheel angle of the agricultural machine, and when the automatic driving is stopped, a timer is cancelled.

Further, the agricultural machinery path planning and real-time tracking method comprises the following steps:

the method comprises the steps of establishing constraint conditions and objective functions of paths by constructing an agricultural machinery dynamics model, and establishing a tracking control method to realize agricultural machinery path planning and real-time tracking;

the agricultural machinery dynamics model establishes the relation between the agricultural machinery state information related to the driving direction, position, speed and attitude angle of the agricultural machinery and the front wheel steering angle of the agricultural machinery as control input;

the agricultural machinery dynamic model comprises a dynamic model in a linear tracking process and a dynamic model in a turning process;

the dynamic model of the linear tracking process is as follows:

the dynamic model of the turning process comprises:

another object of the present invention is to provide a pesticide spraying intelligent agricultural machine path finding navigation control system for implementing the pesticide spraying intelligent agricultural machine path finding navigation control method, the pesticide spraying intelligent agricultural machine path finding navigation control system comprising:

a vehicle-mounted sensor module: the agricultural machinery running state data collection device is used for collecting agricultural machinery running state data;

a communication module: the system comprises an automatic driving and management module and a vehicle-mounted management module, wherein the automatic driving and management module is used for transmitting relevant driving data to the automatic driving and management module and the vehicle-mounted management module;

a navigation module: the system comprises an industrial personal computer unit, a GPS navigation unit and a visual navigation unit, and is used for carrying out accurate navigation positioning by utilizing a GPS navigation and carrier phase difference technology, namely RTK (real-time kinematic) to acquire related navigation data;

an automatic driving and management module: the system is used for realizing path planning, real-time control and precise spraying of the agricultural machinery through the modified motor or the electro-hydraulic actuator according to the positioning result and the related driving data; calculating a control target of the vehicle-mounted controller;

a vehicle-mounted control module: the agricultural machinery executing mechanism is controlled by the vehicle-mounted controller to run according to the planned path based on the running data, the related planned path and the control target, so that automatic navigation and running control of the agricultural machinery are realized;

agricultural machinery actuating mechanism: the electro-hydraulic steering actuating mechanism is used for driving the agricultural machinery steering oil cylinder to act by adopting the electro-hydraulic proportional reversing valve.

Further, the navigation module includes:

the navigation module comprises an industrial personal computer unit, a GPS navigation unit and a visual navigation unit;

the industrial personal computer unit consists of embedded equipment, an embedded system, a keyboard and an LCD;

the GPS navigation unit consists of a GPS receiving device and a matched antenna;

the visual navigation unit consists of a camera and an image processing module.

Further, the agricultural machinery actuating mechanism includes:

the agricultural machinery executing mechanism comprises a hydraulic controller, a three-position four-way electromagnetic proportional reversing valve, a three-position four-way reversing valve, an overflow valve, a switching valve, a hydraulic oil pipe, a safety valve and two balance valves;

the hydraulic pump is a power element and is used for converting mechanical energy into hydraulic energy;

the hydraulic cylinder and the motor are executive components and are used for converting hydraulic energy into mechanical energy;

three-position four-way electromagnetic proportional directional valve: the hydraulic oil flow control device is used for realizing the flow control of hydraulic oil and the steering control of the agricultural machine;

the three-position four-way reversing valve, the overflow valve and the switching valve are used for controlling the pressure, the direction and the flow of the hydraulic oil;

a safety valve: for controlling the oil pressure of the hydraulic circuit;

a balance valve: for ensuring the pressure of the hydraulic circuit;

the hydraulic tank, the filter and the pipeline are auxiliary elements, and the hydraulic oil is a working medium.

The invention also aims to provide an information data processing terminal for realizing the intelligent pesticide spraying agricultural machinery path finding navigation control method.

Another object of the present invention is to provide a computer-readable storage medium, which includes instructions that, when executed on a computer, cause the computer to execute the intelligent agricultural machinery path-finding navigation control method for pesticide spraying.

In summary, the advantages and positive effects of the invention are: the intelligent agricultural machinery monitoring system can conveniently monitor, manage and operate the intelligent agricultural machinery, is low in use difficulty, easy to popularize, low in cost and simple to install.

The intelligent agricultural machine automatic driving system mainly comprises an industrial personal computer upper computer and a vehicle-mounted controller, completes tasks of path planning, real-time control, precise spraying and the like of the agricultural machine according to information sent by the navigation system and a vehicle-mounted sensor, and is realized through a modified motor/electro-hydraulic actuator.

The invention plans a non-linear path for turning and entering into a working area besides a linear path.

The invention can realize unmanned driving and automatic pesticide spraying, can operate continuously for 24 hours, and reduces the labor intensity of farmers and the harm to human bodies in the pesticide spraying process.

The invention realizes the path tracking precision within 2cm at the speed of 5km/h by a difference algorithm, has high positioning precision and small damage to crops.

The invention ensures the safety of vehicles and human bodies through manual/automatic free switching, remote control emergency automation and multi-sensor fusion technology.

Drawings

Fig. 1 is a flow chart of the intelligent agricultural machinery path-finding navigation control method for pesticide spraying provided by the embodiment of the invention.

Fig. 2 is a flowchart of an automatic driving method according to an embodiment of the present invention.

Fig. 3 is a flowchart of an agricultural machinery automatic driving control method provided by the embodiment of the invention.

Fig. 4 is a schematic structural view of the intelligent agricultural machinery path-finding navigation control system for pesticide spraying provided by the embodiment of the invention.

In the figure: 1. a vehicle-mounted sensor module; 2. a communication module; 3. a navigation module; 4. an automatic driving and management module; 5. a vehicle-mounted control module; 6. agricultural machinery actuating mechanism.

Fig. 5 is a schematic diagram of an overall structure of an intelligent navigation and control system according to an embodiment of the present invention.

Fig. 6 is a schematic diagram of the general structure of an automatic driving system of an intelligent pesticide spraying machine provided by the embodiment of the invention.

Fig. 7 is a schematic diagram of a kinematic model of an intelligent pesticide spraying machine according to an embodiment of the invention.

Fig. 8 is a schematic view of a dynamics model of the intelligent pesticide spraying machine provided by the embodiment of the invention.

Fig. 9 is a schematic view of an ackermann steering mechanism for a vehicle according to an embodiment of the present invention.

Fig. 10 is a schematic diagram of the relationship between the lateral force and the slip angle of the vehicle provided by the embodiment of the invention.

Fig. 11 is a block diagram of a navigation system according to an embodiment of the present invention.

Fig. 12 is a schematic diagram of a hardware integration structure of the agricultural machinery vehicle-mounted integrated navigation system based on GPS positioning according to the embodiment of the present invention.

Fig. 13 is a schematic diagram of a GPS navigation system according to an embodiment of the present invention.

Fig. 14 is a station work diagram provided by an embodiment of the invention.

FIG. 15 is a schematic diagram of a geodetic coordinate system according to an embodiment of the present invention.

Fig. 16 is a schematic diagram of a rectangular spatial coordinate system according to an embodiment of the present invention.

Fig. 17 is a schematic diagram of farmland gridding area division provided by the embodiment of the invention.

FIG. 18 is a schematic view of a path of a conventional agricultural machine according to an embodiment of the present invention.

Fig. 19 is a schematic diagram of an AB line operation path according to an embodiment of the present invention.

Fig. 20 is a schematic view of an arcuate path provided by an embodiment of the present invention.

Fig. 21 is a schematic diagram of a fishtail turning path according to an embodiment of the invention.

FIG. 22 is a schematic diagram of a target path when the operating width is less than the turn diameter, according to an embodiment of the present invention.

FIG. 23 is a schematic diagram of a target path for a work width greater than a turn diameter provided by an embodiment of the present invention.

Fig. 24 is an oil circuit diagram of an electrically controlled hydraulic power system according to an embodiment of the present invention.

In the figure: 1. an oil tank; 2. a constant-current overflow valve; 3. an electromagnetic directional valve; 4. a full hydraulic steering gear; 5. a steering wheel; 6. a stepping motor; 7. And a steering oil cylinder.

Fig. 25 is a block diagram of the general structure of the general steering system according to the embodiment of the present invention.

FIG. 26 is a schematic view of a two-degree-of-freedom autopilot agricultural machine heading tracking model provided by an embodiment of the invention.

FIG. 27 is a block diagram of a course tracking control provided by an embodiment of the present invention.

FIG. 28 is a simulation diagram of a course tracking control provided by an embodiment of the invention.

FIG. 29 is a schematic view of step-tracking simulation of a heading without heading estimation according to an embodiment of the present invention.

FIG. 30 is a schematic diagram of step-tracking simulation of a heading with heading estimation according to an embodiment of the present invention.

FIG. 31 is a schematic view of a course tracking front wheel steering simulation provided by an embodiment of the present invention.

Fig. 32 is a schematic view of the general structure of an intelligent agricultural machinery experiment control system provided by the embodiment of the invention.

Fig. 33 is a comparison diagram of the tracking paths provided by the embodiment of the present invention.

FIG. 34 is a schematic diagram of an X-axis tracking error provided by an embodiment of the invention.

FIG. 35 is a schematic diagram of a Y-axis tracking error provided by an embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Aiming at the problems in the prior art, the invention provides an intelligent agricultural machinery path-finding navigation control method for pesticide spraying, and the invention is described in detail with reference to the accompanying drawings.

As shown in fig. 1-2, the intelligent agricultural machinery way-finding navigation control method for pesticide spraying provided by the embodiment of the invention comprises the following steps:

s101, setting a job task, selecting a working mode, and determining the start and the end of the job task.

S102, carrying out accurate navigation positioning on the agricultural machine by utilizing a GPS navigation and carrier phase differential technology, namely RTK (real-time kinematic), and acquiring navigation positioning information of the agricultural machine; and acquiring the state of the actuator and the running state information of the agricultural machine by using the vehicle-mounted controller.

And S103, automatically planning a driving path according to the positioning result, the related driving data and the operation task.

And S104, calculating a control target of the vehicle-mounted controller according to the current state of the agricultural machine and the planned path, and sending the control target to the vehicle-mounted controller.

And S105, the vehicle-mounted controller completes real-time control on the agricultural machine according to the reference control target and the agricultural machine state information.

In step S102, the agricultural machinery navigation positioning information provided by the embodiment of the present invention includes, but is not limited to, longitude and latitude, UTC time, ground speed, ground heading, roll angle, pitch angle, and positioning accuracy of an agricultural machinery position.

In step S102, the method for accurately navigating and positioning an agricultural machine provided by the embodiment of the present invention includes:

In step S103, the path planning method provided in the embodiment of the present invention includes:

modeling the farmland environment by a grid method, and then planning the path of the farmland sub-region by adopting a linear-circular arc operation path algorithm.

(1) Establishing a farmland environment model by adopting a grid method:

firstly, a farmland area is represented by grids, the grids without obstacles are called barrier-free grids, the grids with obstacles are called barrier grids, and the size of each unit grid is determined according to the motion state of the agricultural machinery; obtaining position information of beacon nodes in a farmland through an RTK-GPS; determining the basic shape of the farmland through the position coordinates of the beacon nodes arranged on the farmland corners and the boundaries, and determining the position coordinates of the obstacles in a plane coordinate system of the farmland according to the relative positions of the obstacles in the farmland and the farmland corners and the boundaries; and obtaining a farmland grid map.

Secondly, each grid in the farmland grid map is represented by using a rectangular coordinate method and a serial number method.

The rectangular coordinate method comprises the following steps: the number of grids in each row and each column is 40, the farmland is composed of 40 multiplied by 40 grids to form a grid matrix, and each grid is represented by the coordinates of the center point of the grid.

And the rectangular coordinate codes and the serial number codes of the grids are in one-to-one correspondence.

(2) Analyzing a straight line-arc operation path: selecting three sections of circular arcs as turning paths under the condition that d is less than or equal to 2 r; the turning path of the three arcs is formed by smoothly connecting the three arcs, and the radius of the three arcs is the same as the circle center.

(3) Planning a straight line-arc operation path: and generating a target path for the operation of the agricultural machine by combining the straight line and the circular arc line.

And generating a target path according to the information related to the position of the work starting point, the work width, the work path length and the direction input by the user.

the operation width is the distance between two adjacent straight paths in the operation process of the agricultural machine, under the condition that the operation width is smaller than the turning diameter, the agricultural machine turns according to a three-section arc path, at the moment, the agricultural machine needs to be adjusted in the opposite direction of the next operation straight line firstly, then turns, and completes the operation path of the agricultural machine according to the turning strategy.

As shown in fig. 3, the intelligent agricultural machinery way-finding navigation control method for pesticide spraying provided by the embodiment of the invention further comprises:

the automatic driving of the agricultural machinery is started by a built-in timer, and in each timing interruption, path planning or real-time tracking is selected to be executed according to the requirement and the current state of the agricultural machinery.

When the task is started or under the condition of finishing the planned path, path planning is carried out according to the requirement, otherwise, the agricultural machinery executes a control program for real-time tracking.

And when the path planning is executed, planning an optimal path for the agricultural machinery to enter the target path according to the current position, speed, driving direction related information of the agricultural machinery and the information of the target path.

The agricultural machinery path planning and real-time tracking method provided by the embodiment of the invention comprises the following steps:

the constraint conditions and the objective function of the path are established by constructing an agricultural machinery dynamics model, and a tracking control method is established to realize agricultural machinery path planning and real-time tracking.

The agricultural machinery dynamics model establishes the relation between the agricultural machinery state information related to the driving direction, position, speed and attitude angle of the agricultural machinery and the front wheel steering angle of the agricultural machinery as control input.

The agricultural machinery dynamic model comprises a dynamic model of a straight line tracking process and a dynamic model of a turning process.

The dynamic model of the linear tracking process is as follows:

the dynamic model of the turning process comprises:

as shown in fig. 4 to 6, the intelligent agricultural machinery way-finding navigation control system for pesticide spraying provided by the embodiment of the invention comprises:

vehicle-mounted sensor module 1: the agricultural machinery running state data collection device is used for collecting agricultural machinery running state data.

The communication module 2: the vehicle-mounted management module is used for transmitting the related driving data to the automatic driving and management module and the vehicle-mounted management module.

The navigation module 3: the system comprises an industrial personal computer unit, a GPS navigation unit and a visual navigation unit, and is used for carrying out accurate navigation positioning by utilizing a GPS navigation and carrier phase differential technology, namely RTK (real-time kinematic) to acquire related navigation data.

The automatic driving and management module 4: the system is used for realizing path planning, real-time control and precise spraying of the agricultural machinery through the modified motor or the electro-hydraulic actuator according to the positioning result and the related driving data; and calculates a control target of the onboard controller.

The vehicle-mounted control module 5: the method is used for controlling the agricultural machinery executing mechanism to run according to the planned path by using the vehicle-mounted controller based on the running data, the related planned path and the control target, so as to realize automatic navigation and running control of the agricultural machinery.

Agricultural machinery actuating mechanism 6: the electro-hydraulic steering actuating mechanism is used for driving the agricultural machinery steering oil cylinder to act by adopting the electro-hydraulic proportional reversing valve.

The navigation module 3 provided by the embodiment of the invention comprises:

the navigation module 3 comprises an industrial personal computer unit, a GPS navigation unit and a visual navigation unit.

The industrial personal computer unit consists of embedded equipment, an embedded system, a keyboard and an LCD.

The GPS navigation unit consists of a GPS receiving device and a matched antenna.

The visual navigation unit consists of a camera and an image processing module.

The agricultural machinery actuating mechanism 6 provided by the embodiment of the invention comprises:

the agricultural machinery actuating mechanism comprises a hydraulic controller, a three-position four-way electromagnetic proportional reversing valve, a three-position four-way reversing valve, an overflow valve, a switching valve, a hydraulic oil pipe, a safety valve and two balance valves.

Wherein, the hydraulic pump is the power component for inciting somebody to action mechanical energy converts hydraulic energy into.

The hydraulic cylinder and the motor are executive components and are used for converting hydraulic energy into mechanical energy.

Three-position four-way electromagnetic proportional directional valve: the hydraulic oil flow control device is used for realizing the flow control of hydraulic oil and the steering control of agricultural machinery.

The three-position four-way reversing valve, the overflow valve and the switching valve are used for controlling the pressure, the direction and the flow of the hydraulic oil.

A safety valve: for controlling the oil pressure of the hydraulic circuit.

A balance valve: for ensuring the pressure of the hydraulic circuit.

The technical solution and technical effects of the present invention are further described below with reference to specific embodiments.

Example 1:

1. intelligent agricultural machinery system overall structure design and optimization

The intelligent agricultural machinery system is complex in composition structure and needs cross fusion of multiple subject fields such as machinery, fluid, electronic information and control engineering. Therefore, before the detailed design of the intelligent agricultural machinery system platform is developed, the system scheme needs to be determined and is decomposed into a plurality of subsystems, so that the logical relationship among the functional modules is integrated, and a clear design idea is provided for the control system.

The problem needs to develop an intelligent agricultural machinery system platform which can realize functions of autonomous driving, positioning navigation, path planning and the like aiming at pesticide spraying in the field. The developed intelligent agricultural machine can collect and process field information, generate an electronic map, plan an optimal driving path and automatically drive according to the planned path. Meanwhile, information such as the running speed of the agricultural machine, the pesticide spraying amount and the positioning of the agricultural machine needs to be acquired, and meanwhile, manual remote intervention can be carried out on the running state of the intelligent agricultural machine, so that the stability and the safety of the intelligent agricultural machine are ensured. The specific indexes are as follows:

(1) the structural form is as follows: unmanned intelligent pesticide sprays.

(2) GNSS reception frequency: beidou B1, B2 and B3. GPS L1, L2; GLONASS L1, L2.

(3) GNSS start-up time: for 20 sec.

(4) GNSS update rate: 1-10 Hz.

(5) The system overall identification and planning time is 200 ms.

(6) And the high-precision path tracking within 2cm is achieved at the speed of 5 km/h.

(7) The crop pest and disease identification rate reaches over 90 percent.

(8) The medicine-box volume is 3000L.

(9) The steering mode is as follows: and (6) hydraulic steering.

(10) The spray bar is unfolded for 18000 mm.

(11) A driving mode: four-wheel hydraulic drive.

(12) The number of the spray heads is 49.

(13) The ground clearance is 1100 mm.

(14) The maximum tread is 1250 mm.

(15) The engine power is 140 horsepower.

(16) The dimensions of the profile are length, width, height 6210, 3250, 3010.

On the basis of fully referring to the design concept of advanced intelligent agricultural machinery at home and abroad, a first-generation intelligent agricultural machinery model machine is independently designed, and the intelligent agricultural machinery platform comprises an automatic driving and management system, an agricultural machinery automatic driving system, mobile internet communication and other auxiliary components.

1.1 automatic Driving and management System

Compared with the traditional pesticide spraying agricultural machine, the intelligent cotton pesticide spraying agricultural machine is additionally provided with an intelligent navigation and control system, the system can obtain an accurate agricultural machine positioning result according to data of GPS navigation and carrier phase differential technology (RTK) navigation, plan a driving path of the agricultural machine according to the navigation positioning result, driving state data collected by a vehicle-mounted sensor and a task requirement of a user, and control the agricultural machine to realize intelligent monitoring and management of the agricultural machine in real time according to the path. The general architecture of this system is shown in fig. 5:

the invention mainly focuses on automatic navigation and driving control of field operation of the intelligent pesticide spraying machine, and the covered work mainly comprises the following steps:

1) automatic navigation technology based on GPS navigation.

2) Automatic driving technology of agricultural machinery in the field.

3) And (5) mechanical, electrical and hydraulic transformation of an agricultural machinery control system.

The intelligent agricultural machine automatic driving system mainly focuses on automatic navigation and driving control of field operation of the agricultural machine, and the intelligent agricultural machine automatic driving system mainly comprises an industrial personal computer upper computer and a vehicle-mounted controller, and is used for completing tasks such as path planning, real-time control, precise spraying and the like of the agricultural machine according to information sent by a navigation system and a vehicle-mounted sensor, and is realized through a modified motor/electro-hydraulic actuator. The general structure of the autopilot system is shown in fig. 6:

the automatic driving process of the intelligent pesticide spraying agricultural machine mainly comprises the following steps:

1) the user sets a job task through the automatic driving and management system, selects a work mode, and determines the start and end of the job task.

2) The automatic driving and management system and the vehicle-mounted controller acquire information such as navigation positioning information, actuator state and agricultural machine running state of the agricultural machine.

3) And the automatic driving and management system plans an automatic driving path according to the relevant information of the agricultural machinery and the operation task.

4) And the automatic driving and management system calculates a control target of the vehicle-mounted controller according to the current state of the agricultural machine and the planned path and sends the control target to the vehicle-mounted controller.

5) And the vehicle-mounted controller completes real-time control on the agricultural machine according to the reference control target and the agricultural machine state information.

The main steps of the work completed by the automatic driving and management system on the upper computer in the automatic driving system comprise:

1) and (4) setting the work task of the agricultural machine by a user and monitoring the working state of the agricultural machine.

2) Planning the operation path of the agricultural machine.

3) And controlling the intelligent agricultural machine to track the operation path in real time.

4) And managing information related to the agricultural machinery.

The operation of the automatic driving control system is shown in fig. 2:

the intelligent agricultural machinery can be conveniently monitored, managed and operated by a user of the upper computer, the use difficulty is low, and the popularization is easy. On the other hand, the upper computer is installed on the agricultural machine only by installing the required application program on the industrial personal computer, so that the cost is low, and the installation is simple.

The upper computer can communicate with the vehicle-mounted sensor, the navigation receiver and the control system.

1.2 automatic driving system of agricultural machinery

The upper computer of the intelligent agricultural machine platform needs to realize functions of planning a driving path, tracking in real time and the like, and automatic driving of the agricultural machine is realized. The agricultural machinery automatic driving system provided by the invention mainly comprises the following functions:

1) planning the operation and running path of the agricultural machine.

2) Starting and stopping the automatic driving of the agricultural machine and tracking the target path of the agricultural machine in real time.

3) Manual operation and control under the emergency condition of the agricultural machinery.

The automatic driving function of the agricultural machine is started by a timer arranged in the system, and in each timing interruption, the upper computer control system selects to execute path planning or real-time tracking according to the requirement and the current state of the agricultural machine. When a task is started or under the condition that the planned path is finished, the system plans the path according to the requirement, otherwise, the agricultural machinery executes a control program of real-time tracking. When the path planning is executed, the control system plans an optimal path for the agricultural machinery to enter the target path according to the information of the current position, speed, driving direction and the like of the agricultural machinery and the information of the target path. When the real-time control is executed, the control system calculates the input of a vehicle-mounted control system on the agricultural machine according to the running deviation of the agricultural machine, and the vehicle-mounted control system takes the input as a reference target to control the steering wheel angle and the like of the agricultural machine. The timer is cancelled when the user suspends the automatic driving. The flow of the automatic driving control of the agricultural machinery is shown in figure 3:

the path planning pesticide spraying machine is carried out according to the current position, speed, driving direction and the like and a target path set by a user. In previous research and application, automatic driving of agricultural machinery is limited to coverage of a straight path. The system of the present invention plans a non-linear path for turning or entering the work area in addition to a linear path.

In the real-time target tracking process of the intelligent agricultural machine, the automatic driving and management system can calculate control references such as a target steering angle, a target speed and the like of the agricultural machine in real time according to a planned automatic driving path and the current driving state of the agricultural machine and input the control references into the vehicle-mounted control system.

1.3 agricultural machinery navigation positioning

The navigation and positioning functions of the invention are realized mainly by a GPS navigation system. The navigation data is received by the GNSS receiver and then is sent to the automatic driving and navigation system of the upper computer by the communication module. Besides navigation data, the receiver also integrates an RTK positioning technology and an inclination angle sensor, can select different positioning modes, and can provide information such as the driving direction, speed, attitude angle and the like of the agricultural machinery.

The message of GPS navigation is composed of a communication application instruction, information length, a user address, message information, a CRC verification code and the like. Through the verification and the splitting of the message, the user can obtain the required navigation information. By sending different data request instructions to the receiver, the user can obtain different navigation data, and the navigation data required in the system mainly comprises: longitude and latitude, UTC time, ground speed, ground course, roll angle, pitch angle, positioning accuracy and the like of the position of the agricultural machine.

2. Intelligent agricultural machinery dynamics modeling

The automatic driving system of the intelligent agricultural machine needs to provide functions of agricultural machine path planning and real-time tracking, the constraint condition and the objective function of a path need to be established according to an agricultural machine model in the path planning process of the agricultural machine, and the tracking control method needs to be established on the basis of the agricultural machine model in the real-time tracking process of the agricultural machine. It is therefore necessary to build a model of an intelligent agricultural machine.

The intelligent pesticide spraying agricultural machine is mainly controlled to control the driving direction of the agricultural machine, and the automatic driving can acquire the state information of the agricultural machine, such as the driving direction, the position, the speed, the attitude angle and the like of the agricultural machine according to a GPS navigation system and a vehicle-mounted sensor. The model of the agricultural machine needs to establish the state variable and of the agricultural machine

The model of the intelligent agricultural machine can be established by using a dynamics method or a kinematics method, two different methods are respectively used for establishing the model of the intelligent agricultural machine, and the application ranges of the different models are analyzed.

1.1 kinematic description of Intelligent agricultural machinery

The kinematic model of the intelligent agricultural machine can be simplified into a two-wheel model with two degrees of freedom, as shown in fig. 7:

the turning angle of the front wheel is set as l, the wheelbase of the front wheel and the rear wheel is set as l, and the wheelbase of the front wheel, the rear wheel and the rotation center of the agricultural machine is set as l_f、 l_r. The position coordinates of the agricultural machine on the ground coordinate system are (X, Y), the running speed of the agricultural machine is v, and the running direction angle is

When the control of the automatic driving process of the intelligent agricultural machine is investigated, the investigation needs to be carried out from the coordinate system of the agricultural machine. When the kinematics model is established, a reference system is established at the center of gravity of the agricultural machine, and the driving direction of the agricultural machine is taken as the x axis of the reference system. In the running process of the agricultural machine, a target path appointed by an operator needs to be tracked, the distance between the current position of the agricultural machine and the target path is defined as the transverse deviation of the agricultural machine, and the angle difference between the current running direction of the agricultural machine and the target running direction at the position closest to the current running direction on the target path is defined as the direction deviation of the agricultural machine. During the process of executing the automatic running task, the running speed of the agricultural machine is approximately constant.

And obtaining a kinematic equation of the agricultural machine according to the geometric relation between the speed and the rotation angle in the driving process of the agricultural machine.

The position deviation and the direction deviation of the agricultural machine are defined as follows:

in the formula (X)_d，Y_d) -the location of the projected point of the current position of the agricultural machine on the target path;

-target direction angles corresponding to the projection points.

The corresponding kinematic equation is:

the second derivative of the position and orientation deviation is:

due to limited front wheel steering angle and steering rate of agricultural machinery, i.e. with

Finite, second derivative of (3-4) directional deviation

Limited, this can become a constraint to consider in path planning.

According to the model, the minimum turning radius of the running agricultural machine is

In the formula_maxThe maximum front wheel turning angle of the agricultural machine is determined by the structure of the agricultural machine.

2.2 dynamics model of Intelligent agricultural machinery

In the kinematics model, the sliding of wheels of the agricultural machine in the driving process is not considered, and the situation that the wheels of the agricultural machine slide is easy to occur due to the fact that the working farmland of the intelligent agricultural machine is usually uneven, and the kinematics model cannot accurately reflect the driving process of the intelligent agricultural machine under the situation. Therefore, the design of the control system of the project further considers the dynamic model of the intelligent agricultural machine.

The agricultural machinery is simplified into a two-wheel model with two degrees of freedom in the design of the invention, and the main part of the model is shown in figure 8. In order to research the driving process of the agricultural machine, a reference system is established according to the driving direction of the agricultural machine, and the gravity center of the agricultural machine is taken as an origin. In the working process of the agricultural machinery, the running speed is close to a constant speed, and in the design of a control system, the front wheels of the vehicle can be assumed to run at a constant longitudinal speed.

According to fig. 8, the stress of the wheel is decomposed according to the transverse direction and the longitudinal direction of the wheel. The speed of the agricultural machine in the running direction is approximately constant, so that the control of the running process of the agricultural machine only needs to consider the kinetic equation of the transverse direction and the turning, the kinetic equation of the rotation of the agricultural machine in the vertical running direction and the horizontal plane is calculated, and the following can be obtained:

where m is the mass of the vehicle.

F_yr-lateral forces on the rear wheel;

F_yf-lateral forces on the front wheels;

F_xr-longitudinal forces on the rear wheel;

F_xf-longitudinal forces on the front wheel;

α_r-the slip angle of the rear wheel;

α_f-the slip angle of the front wheel;

-lateral acceleration of the center of gravity of the agricultural machine.

According to the Ackerman steering principle shown in FIG. 9, the steering angles of the wheels on the left side and the right side of the vehicle are different, and the steering angles of the wheels meet the following conditions:

where k is the distance between the left and right wheels, l is the distance between the front and rear wheels, α_r1And α_r2Slip angles of the front wheels at the outside and inside of the turn, α_f1And α_f1The slip angles of the rear wheels on the outside and inside of the turn are the same. Considering the difference between the rotation angles of the left wheel and the right wheel, the dynamics model of the agricultural machine is as the formula (3-7):

the dynamic model considering different steering angles of the left wheel and the right wheel is complex and is not beneficial to the calculation of the real-time tracking control process. The agricultural machinery model is equivalent to a two-wheel model, and the path real-time tracking control in the invention is always effective to realize the path real-time tracking control by taking the corners of the front wheel and the rear wheel under the two-wheel model as a control target, so that the control accuracy can be ensured, and the method is adopted to establish the agricultural machinery dynamics model. The lateral force applied to the agricultural machinery is positively correlated with the wheel slip angle, and the relationship between the lateral force and the wheel slip angle obtained according to the correlation experiment is shown in fig. 10. In the working process of the agricultural machinery, the running speed is slow, the slip angle of the wheel is small and basically maintained within 5 degrees, and in the application range of the linear model, the transverse stress of the tire and the slip angle of the wheel are approximately in a linear relation, and the expression of the relation is as follows:

in the formula C_af-the steering stiffness of the front wheels;

C_ar-steering stiffness of the rear wheels.

The longitudinal stress of the agricultural machinery wheel is frictional force, and the expression is as follows:

F_xf＝F_xr＝μmg (3-9)

the coefficient of friction between the wheel and the road surface can be calculated by using the Burckhardt method.

Defining a speed direction angle theta of the front and rear wheels_fAnd theta_rRespectively is as follows:

θ_f＝-α_f(3-10a)

θ_f＝-α_f(3-10b)

the relation between the speed direction angle of the front wheel and the rear wheel and the motion state of the agricultural machine can be obtained:

defining the position of the agricultural machine on the geodetic coordinate system as (X, Y), the movement of the agricultural machine in the geodetic coordinate system can be described as:

the agricultural machinery needs to travel according to a preset path in the operation process, and the reference path is set as follows: y is_d＝f_ref(X), the target direction angle corresponding to the arbitrary position of the reference path is as follows:

the error of the agricultural machine tracking the reference path comprises a transverse error and a direction error, wherein the transverse error is a transverse distance between the position of the agricultural machine and the reference path, namely e_YAnd y, the direction error is the difference between the driving direction angle of the agricultural machine and the direction angle at the reference point on the reference path:

taking a point on the reference path closest to the position of the agricultural machine as a reference position, and enabling a connecting line of the position of the agricultural machine and the reference position to be vertical to the reference path, namely:

substituting into formula (3-13a) can obtain:

2.2.2 kinetic model of Linear tracking Process

In the straight-line tracking process, the front wheel steering angle is usually within ± 15 °, satisfying the small angle assumption. On the other hand, the running speed of agricultural machinery is slower, a_fAnd a_rTypically within 5 deg., again satisfying the small angle assumption. Under this assumption, the kinetic model of the agricultural machine in equation (3-5) can be simplified as:

in a is_fAnd a_rThe above equation can be further simplified under the assumption of 0.

Under the assumption of a small angle, the speed angle of the front and rear wheels can also be approximated as:

namely, it is

Since the reference path to be tracked is a straight line,

the first and second derivatives of the error of agricultural machine driving are:

therefore, the temperature of the molten metal is controlled,

substituting the equations (3-19) and (3-21) into the equations (3-17) of the kinetic equation,

2.2.3 dynamics model of the cornering Process

The front wheel turning angle during turning is greater than the front wheel turning angle during straight-line tracking, and a_fAnd a_rStill remaining within a small range, satisfying the small angle assumption, the model of agricultural dynamics in equation (3-5) can be simplified as:

consider a_fAnd a_r0, the kinetic model can be further simplified to:

substituting the formulas (3-8) and (3-9) to obtain

Combining the formula (3-10) with the formula (3-11), can be derived

The agricultural machinery dynamics model under the large-angle turning condition is highly nonlinear and has high coupling degree. The control system in the project is realized based on a kinematic model in the turning process control of the agricultural machinery automatic driving.

3. Agricultural machinery positioning and navigation system design

3.1 general design of field navigation System

The overall design concept of the field operation integrated navigation system based on the GPS satellite is shown in FIG. 11. The system mainly comprises an industrial personal computer, a GPS navigation system and a visual navigation system. The industrial personal computer is composed of embedded equipment, an embedded system, a keyboard, an LCD and the like. The GPS navigation system mainly comprises a GPS receiving device and a matched antenna. The visual navigation system consists of a camera and an image processing module. For the whole navigation system, the BDS information is mainly received, the latitude and longitude information is subjected to filtering processing through a Kalman filtering algorithm, the data of the visual sensor is acquired, and the received data of the BDS and the visual sensor are subjected to fusion processing. Displaying a plot boundary on a screen through position and attitude information data received by a BDS receiver and other sensors, and planning a reasonable operation path according to plot conditions, operation requirements and the like; when the agricultural machine works, the working condition is displayed in real time through the dynamic tracking data of the BDS and the multi-sensor, and the vehicle-mounted automatic navigation of the agricultural machine is realized through the navigation function.

3.2 System hardware design

According to the design scheme of the field navigation system, the hardware composition and the implementation function of the field navigation system are analyzed respectively, the requirements of the system on the hardware are summarized, and the hardware type selection of the system is facilitated.

The field navigation system is mainly responsible for generating a farmland information profile map, planning a path according to a path planning algorithm, receiving and processing GPS positioning information and visual navigation information, and simultaneously performing fusion processing on the GPS information and the visual navigation information, so the field navigation system is composed of a processing core component industrial control board, GPS positioning receiving equipment and the like, and has the following functions:

(1) the field navigation system needs to process complex position information of a farmland, and the system needs to run C + + software, so that the field navigation system needs to have good data processing capability and high logic operation speed.

(2) The field navigation system needs to work in a large-scale farmland environment, is convenient to popularize in a large scale, needs low-cost high-precision GPS positioning, and meanwhile, the system needs to accurately position and measure the length and the like of each regional plot of the farmland in real time, so that system hardware needs to have good stability, and the positioning precision of the GPS positioning receiving equipment reaches a sub-meter level.

(3) The field navigation system needs to be interconnected with a GPS receiving device, a visual navigation device, a display screen, a mouse and other devices, and therefore, rich peripheral interfaces are needed to be provided so as to be in information interconnection with the peripheral devices.

(4) The industrial personal computer needs to install embedded GIS software to generate a routing chart and receive field positioning information provided by GPS receiving equipment. In addition, the agricultural machine is automatically navigated by combining the current positioning and speed information of the unit.

The agricultural machinery vehicle-mounted integrated navigation system consists of a vehicle-mounted industrial personal computer, GPS positioning receiving equipment and a machine vision system. Based on the above detailed analysis, an appropriate hardware integration system is selected.

1. After factors such as system cost, development difficulty and the like are comprehensively considered, the domestic GNSS RTK differential GPS equipment is selected for the subject GPS system. The device has high precision and low power consumption, and is suitable for the field of field integrated navigation.

The main parameters of a GPS device are as follows:

power supply voltage: 24VDC +/-5%

Input impedance: 50 omega

Antenna gain: 15 to 30d B

Frequency: GPS L1

Input/output data interface: 2 UART, LVTTL level, baud rate 4800 ~ 115200bps

Cold start: 10s

And (3) hot start: 1s

Recapture time: <1s >

Positioning accuracy: 5cm

Data update rate: 1Hz (upgradable)

Navigation data format: NMEA 0183.

2. The industrial personal computer is a core component for processing various information in the whole system and a center of man-machine conversation, and the industrial personal computer can operate an embedded C + + system platform because the generation or loading of a farmland contour map is completed on C + + software. The system needs to run C + + compiling software, and the data processing storage capacity of the algorithm is large, so that a high-performance processing chip with good data processing capacity and high logic operation speed is needed. The industrial personal computer needs to be interconnected with devices such as a positioning receiving device and a visual navigation system for data communication, the two devices exchange information through an RS-232 serial port, and therefore an interaction terminal needs to be provided with more than 2 serial ports, namely COM1 and COM 2. The navigation system needs to be interconnected with a display screen and a mouse, and displays and processes state information, farmland profile maps and man-machine conversation information of each system, so that a rich peripheral interface and a good man-machine conversation function are needed. In addition, the industrial personal computer needs to perform mobile work for a long time in a complex farmland environment, and therefore the industrial personal computer also needs to have the characteristics of good stability, small size and easiness in vehicle-mounted operation.

In consideration of the above requirements, the invention selects the industrial personal computer of the Tuhua ARK-3500 as a system control center. The main properties are as follows:

(1) support for

Core^TMi3/i5/i7 Mobile Serial processor (rPGA) + Intel QM77 Chipset

(2) The third generation Core i processor supports independent three displays: DVI + HDMI + DisplayPort

(3) The memory supports DDR3/DDR3L SO-DIMM with the maximum size of 16GB

(4)2 expansion slots capable of supporting PCI, PCIe x 1 and PCIe x 4 expansion cards

(5)9-34V wide voltage DC power input

(6) Rich I/O interface, including 4 × USB 3.0 and 8 × COM

(7) Resilient storage selection, support 2 × mSATA, 1 × CFast and 2 × 2.5' SATA HDD/SSD

(8) Support iManager, SUSIAccess and embedded software APIs

3. When the agricultural machinery vehicle-mounted navigation system works, a display screen is needed to display relevant state quantities of agricultural vehicles, a farmland electronic information map and the like, and parameters are configured through a keyboard, a mouse and the like. In addition, when the farmland electronic information map needs to be loaded with some related files, the files are transferred between the notebook computer and the vehicle-mounted industrial personal computer through a U disk or a CF card as a medium. Therefore, the system selects four-wire resistive touch screen, mouse, USB flash disk, keyboard and other input and output devices, so as to realize humanized man-machine conversation function of the system.

4. The selected hardware components are integrated to form the combined navigation system designed by the subject, the system hardware integration structure is shown in figure 12, GPS positioning receiving equipment transmits positioning information to a vehicle-mounted industrial personal computer through an RS232 interface, a machine vision system transmits acquired information to a vehicle-mounted computer through the RS232 interface, a farmland information distribution diagram is transmitted between the vehicle-mounted computer and a notebook computer through a U disk, and a display screen, a keyboard and a mouse have a man-machine conversation function.

3.3 Farmland location Algorithm study

The GPS works in a differential mode, the base station uses a GPS receiver with the base station, the transmission and the reception of differential correction signals are carried out by using a pair of GPS radio stations, and the mobile station uses another receiver and is connected with an industrial personal computer through an RS232 serial port. The effective coverage radius of the GPS differential correction signal is about 10 kilometers, the whole demonstration area range can be covered, and the GPS positioning data can be ensured to have centimeter-level precision.

3.3.1 satellite navigation System composition

The GPS system consists of three parts, a GPS navigation satellite, a ground monitoring system, and a user equipment GPS signal receiver, as shown in fig. 13.

The GPS system positioning principle can be described simply as follows: the GPS navigation satellite in the space continuously transmits satellite ephemeris signals to the ground, and the satellite ground control center receives the satellite ephemeris signals through professional equipment, resolves the ephemeris signals, determines information such as the operation orbit of the navigation satellite and returns the information such as the operation orbit of the satellite to the navigation satellite. The navigation satellite simultaneously propagates the information such as the orbit in its transmitted radio signal. The user receiving equipment mainly refers to a GPS receiver, and the GPS receiver receives and measures wireless signals transmitted by a visible satellite, acquires information such as a running orbit of a navigation satellite and the like, and performs position calculation to further obtain three-dimensional position, three-dimensional direction, movement speed, time information and the like of the user receiver.

(1) Ground control part

The plurality of master control stations, the monitoring station and the injection station form a ground control part. The main control station collects and processes observation data information from distributed monitoring stations, generates integrity information, wide area difference information and satellite navigation messages, and realizes the scheduling and planning of tasks, the management and control of system operation and the like. The main control station controls the injection station to realize the injection of integrity information, wide-area differential information and satellite navigation messages, and well manages and controls loads. The monitoring station has the functions of continuously tracking and monitoring the navigation satellite and receiving navigation signals, transmitting the received information to the main control station, and simultaneously has the functions of determining the satellite orbit and providing observation data for time synchronization.

(2) User part

The user part mainly comprises terminals supporting other navigation systems and users of the GPS navigation system. The user receiver can track the GPS navigation satellite to acquire time information in real time, calculate the position coordinate, the moving speed and the like of the user receiver, and can be manufactured into a portable type, an airborne type, a shipborne type, a vehicle-mounted type and the like according to the requirements of different industries.

3.3.2 coordinate System conversion

In GPS mapping and positioning applications, there are two general categories of coordinate systems that are commonly employed. One type is a celestial coordinate system, which is independent of the earth rotation, called a space-solid coordinate system, and is suitable for describing the running state of a satellite and determining the orbit of the satellite. The other is an earth coordinate system, which is fixed on the earth and rotates with the earth, also called a geostationary coordinate system. The method is a non-inertial coordinate system, and is very convenient for expressing the position of a point and processing GPS positioning data.

In agriculture, the earth-fixed coordinate system is mainly used, since only the application of GPS measurements on the earth's surface is of interest. The earth-fixed coordinate system has various expression forms, and for GPS measurement, the most basic is an earth center coordinate system with the earth center of mass as an origin. The common geocentric coordinate system includes a geodetic coordinate system and a rectangular spatial coordinate system.

The geodetic coordinate system is defined as: the center of the ellipsoid of the earth coincides with the center of mass of the earth, the short axis a of the ellipsoid coincides with the rotation axis of the earth, and the initial meridian plane of the ellipsoid coincides with the Greenwich meridian plane. As shown in fig. 15, geodetic coordinates of a ground point P are described by geodetic longitude (L), geodetic latitude (B), and geodetic height (H). The geodetic longitude is the included angle between the meridian plane of the ellipsoid passing through the point and the Greenwich mean meridian plane, the geodetic latitude is the included angle between the normal line of the ellipsoid passing through the point and the equatorial plane of the ellipsoid, and the geodetic height is the distance from the point to the ellipsoid along the normal direction of the ellipsoid.

The definition of the space rectangular coordinate system is as follows: the origin O of the coordinate system coincides with the center of mass of the earth, the Z axis points to the north pole of the earth, the X axis points to the intersection point of the Greenwich mean meridian plane and the equator of the earth, and the Y axis is perpendicular to the Z plane of the cutting edge and forms a right-hand coordinate system with the Z axis and the X axis, as shown in FIG. 16. The position of any point in space is represented by (X, Y, Z) coordinates.

The position of any point on the earth can be represented as (B, L, H) and (X, Y, Z), and the two representation methods can be converted with each other. The formula for converting geodetic coordinates into spatial rectangular coordinates is formula 4.1:

in the formula: n is the curvature radius of the prime circle of the ellipsoid, and e is the first eccentricity of the ellipsoid.

3.3.3 systematic positioning error

The error existing in the system mainly comes from the error generated in the satellite measurement process, and the error can be summarized as follows: errors of clocks of the satellites, ephemeris errors (position errors of the satellites), errors caused by antenna multipath effects, atmosphere propagation delay correction residuals, errors generated by receiver ranging, noise of the receivers, elevation measurement errors and the like. In addition, the positioning accuracy is also affected by the geographical terrain where the receiving end of the user is located.

In general, satellite measurement errors can be classified into two categories: one is a random error with weak correlation with rapid temporal-spatial transformation. The other is a random offset error with a slower transformation in time space and a stronger correlation. The strategy of applying the optimized estimation in eliminating the random error is the most common and effective method, the traditional least square method is difficult to reduce various random errors which affect the positioning precision in the navigation data, the BDS navigation data processing aims at reducing the influence of various errors on the dynamic positioning result as much as possible, and one of the most important methods is kalman filtering, namely, a dynamic kalman filter is used for eliminating various random errors in positioning.

4. Farmland area path planning

The agricultural machinery path planning in the agricultural field mainly comprises two parts, namely establishment of a farmland environment model and an agricultural machinery path planning algorithm, wherein the farmland environment is firstly modeled by a grid method, then path planning is carried out on a farmland subregion by adopting a straight line-circular arc operation path algorithm, and finally feasibility of the path planning algorithm is verified.

4.1 establishment of model of Farmland Environment

The classical environment modeling methods include a geometric method, a topological graph method, a grid method and the like. The grid method reduces complexity of modeling the boundary of the obstacle and accurately models the known environment. In the invention, the size and the position of the obstacle in the farmland environment are known and do not change. Based on the assumptions, a grid method is adopted to model the farmland area.

The method is characterized in that the farmland does not contain large obstacles such as forests and the like, and the obstacles mainly refer to riprap areas where wheat cannot be planted, areas with irrigation facilities or reserved blank areas and the like.

The grid method is to use grids to represent farmland areas, the grids without obstacles are called barrier-free grids, the grids with obstacles are called barrier grids, the size of each unit grid is determined according to the motion state of the agricultural machinery, and the minimum turning radius of the agricultural machinery is 2.5m, so the unit grids are represented by squares with the side length of 2.5 m.

The position information of the beacon nodes in the farmland is obtained through an RTK-GPS during deployment, the basic shape of the farmland is determined through the position coordinates of the beacon nodes arranged on the farmland corners and the boundaries, and then the position coordinates of the obstacles in the farmland plane coordinate system are determined according to the relative positions of the obstacles in the farmland and the farmland corners and the boundaries. Assuming that the farmland is a rectangular area of 100m x 100m, the vertex of the farmland in the southwest 45 direction is taken as the origin of a coordinate, the x axis horizontally points to the right in the east direction, and the y axis vertically points to the north direction. The farmland region is subjected to grid division along the horizontal direction and the vertical direction by using 2.5m as the side length of a grid unit, and the farmland grid map obtained by the grid division is shown in fig. 17:

the black grid represents an obstacle grid on which the agricultural machine cannot perform work, and the white grid represents an obstacle-free grid on which the agricultural machine can perform work. When the obstacle is less than one grid, the obstacle is represented by one grid.

In order to plan the path of the agricultural machinery working area, each grid in fig. 17 is represented by two methods, namely a rectangular coordinate method and a sequence number method.

A rectangular coordinate method: in the figure, the number of grids in each row and each column is 40, and the farmland is composed of 40 multiplied by 40 grids to form a grid matrix, and each grid is represented by the coordinates of the center point of the grid.

Sequence number method: all grids are numbered decimal from left to right and from bottom to top.

The rectangular coordinate codes and the serial number codes of the grids are in one-to-one correspondence.

4.2 straight-arc operation Path resolution

On the field of intelligence agricultural machinery work, the crop can be generally planted according to certain direction and arrange, in the agricultural machinery working process, can go along the direction of arranging of crop, traverses each ridge crop in proper order. Compared with an automatic driving vehicle running on a road, the running path of the tractor in the farmland is relatively fixed, a user can plan a target path of the agricultural machine before the start of work, and the intelligent agricultural machine automatically runs according to the target path to complete a task in the working process.

The farmland operation driving process of the intelligent agricultural machine can be divided into three stages:

1) the target phase is entered into and the target phase,

2) a straight-line tracking stage, wherein,

3) and turning the field. After the agricultural machine enters a target route, tasks of a linear tracking stage and a field head turning stage are repeatedly and alternately executed until traversal of all operation areas of the field is completed. When the intelligent agricultural machinery operation task planning starts, a user needs to provide relevant information of an operation route to complete the planning of a target path.

In many areas of China, cultivated land resources are scarce, and agricultural machinery operation needs to ensure high land utilization rate. The space left for the agricultural machinery to turn on the ground in the field is small, so that the driving path of the agricultural machinery in the turning process is required to be as short as possible, and on the other hand, the short turning driving distance is also beneficial to improving the efficiency of the agricultural machinery operation. The target path planning function of the system needs to plan the shortest path when the farm machinery turns around in the field. When the agricultural machinery turns, the structure of the agricultural machinery is limited, and the minimum turning radius has a lower limit, which becomes a constraint condition of a turning path.

In general, when an agricultural machine performs a sowing operation, the operation is performed linearly back and forth in the planting direction of crops, and the operation is turned in a turning area at the head of the field, as shown in fig. 18. Such a working path is mainly constituted by mutually parallel straight paths, and in a field planted uniformly, the distances between the straight lines are approximately equal, which is called a working width. Such a work path is called an AB line, as shown in fig. 19, where d is the work width and l is the path length.

During the turning process of the agricultural machinery, the agricultural machinery needs to turn from one straight path to another straight path approximately parallel to the straight path. A simple and visual method is realized by a path consisting of straight lines and arc sections, wherein the path consists of the straight lines and the arc sections which are smoothly connected, the adjacent straight lines and the arc sections are connected end to end and are tangent at the connecting points, and the driving directions and the positions of the starting point and the ending point of the path are respectively consistent with the driving directions and the positions of the starting point and the final target of the agricultural machine. The satisfaction of the path boundary condition and the continuity constraint can be ensured.

The straight-arc turning path has various choices, including multi-section arcs, arch lines, fishtail lines and the like. The arched turning path is formed by smoothly connecting straight lines and circular arcs, the shortest length of the agricultural machinery turning path can be guaranteed by the arched path, the agricultural machinery does not need to stop in the turning process, the agricultural machinery uses the path to complete turning, the distance d between the two straight lines before and after turning is required to be larger than 2r, and r is the turning radius of the agricultural machinery. A simpler arcuate turning path is shown in fig. 20, in which the agricultural machinery turns from one straight path end to another straight line parallel to and aligned with the straight path end, the turning radius of the agricultural machinery is the same in the stage of departing from the current straight line and entering the target straight line, and the turning angles are both 90 °.

The fishtail turning path is suitable for the condition that d is less than or equal to 2r, the fishtail turning path is shown in figure 21, when the agricultural machinery turns along the path, the agricultural machinery firstly turns 90 degrees along a circular arc, then reverses the running distance (2r-d) along a straight line, and then turns 90 degrees to enter a target straight line. The turning path can ensure short running distance, but the turning process needs stopping and backing, so that the running time of the agricultural machine can be increased, and meanwhile, the accuracy of automatic running of the agricultural machine is also adversely affected. The path is not selected in the planning of the straight line-circular arc path of the project, but three circular arcs are selected as the turning path under the condition that d is less than or equal to 2 r.

The turning path of the three arcs is formed by smoothly connecting the three arcs, and the radius of the three arcs is the same as the circle center. According to the invention, the agricultural machine is turned according to the three-segment circular arc path, the agricultural machine does not need to stop in the turning process, the running direction angle of the agricultural machine can be smoothly transited, and the running path is selected for setting the operation path.

4.3 Linear-circular operation Path planning

In the agricultural machinery management system, a user can input information such as the position of an operation starting and stopping point, the operation width, the length and the direction of an operation path, and the like, and the management system can generate the target path according to the parameters. The running of the agricultural machine is limited by the minimum turning radius, and the ground turning mode of the agricultural machine is influenced by the width of the working machine.

After the agricultural machinery management system obtains the minimum turning radius and the operation width information of the agricultural machinery, the agricultural machinery management system can select a generation strategy of a turning path according to the size relationship of the agricultural machinery and the operation width information. The operation breadth is the distance between two adjacent straight paths in the operation process of the agricultural machine, under the condition that the operation breadth is smaller than the turning diameter, the agricultural machine turns according to a three-section arc path, at the moment, the agricultural machine needs to be adjusted in the opposite direction of the next operation straight line firstly, and then turns, and the operation path of the agricultural machine finished according to the turning strategy is shown in figure 22. If the operation width is larger than the width between the turns, the agricultural machine turns according to the arch-shaped path without the adjustment, and the operation path of the agricultural machine completed according to the turning strategy is shown in figure 23.

5. Agricultural machinery movement and steering control system

5.1 agricultural machinery steering control scheme

The steering actuating mechanisms of the common agricultural machinery at present can be classified into two main types: the electric hydraulic type agricultural machinery steering wheel is driven by a motor, a gear (or a chain, a friction wheel and the like) and the like, and the agricultural machinery steering oil cylinder is driven by controlling an electric hydraulic proportional reversing valve and the like to act.

When the mechanical steering actuating mechanism works, the motor drives the original steering wheel of the agricultural machine to rotate after speed reduction, and steering operation is carried out through the original steering system of the agricultural machine. The angular transmission ratio of the agricultural machinery steering system is usually large, and the effective torque and the rotating speed of the motor are usually low, so that the steering execution speed of the mechanical steering execution mechanism is relatively low, and the difficulty in realizing the accurate control of the mechanical steering execution mechanism is large due to the complex torque transmission relation. Therefore, the electro-hydraulic steering actuating mechanism which drives the agricultural machinery steering oil cylinder to act, such as the electro-hydraulic proportional reversing valve, can be used for realizing the accurate control of the agricultural machinery steering. The designed hydraulic steering structure is shown in the figure and mainly comprises the following components: the hydraulic control system comprises a hydraulic controller, a three-position four-way electromagnetic proportional reversing valve, a three-position four-way reversing valve, an overflow valve, a switching valve, a hydraulic oil pipe and the like. The hydraulic pump is a power element (converting mechanical energy into hydraulic energy), the hydraulic cylinder and the motor are execution elements (converting hydraulic energy into mechanical energy), the functions of the rest valves mainly realize control functions (namely controlling the pressure, direction and flow of hydraulic oil), the hydraulic tank, the filter and the pipeline are auxiliary elements, and the hydraulic oil is a working medium.

The three-position four-way electromagnetic proportional reversing valve has the main functions of realizing the flow control of hydraulic oil and the steering control of agricultural machinery so as to achieve the effect of controlling the steering direction and speed. The hydraulic oil in the system flows through the three-position four-way proportional directional valve, and the oil quantity entering a rod cavity and a rodless cavity in the hydraulic oil cylinder is controlled by controlling the opening size and the oil path direction of the electromagnetic proportional directional valve to execute steering. For the safety of the system oil circuit, a safety valve, namely 5 parts in fig. 24, is arranged at the input front end of the electromagnetic proportional valve, and the oil pressure of the hydraulic circuit is controlled. The oil path block, the electromagnetic proportional directional valve and the safety valve are combined together to form a hydraulic oil control module. Meanwhile, A, B two balance valves are added to ensure that the two balance valves are used for ensuring the pressure of a hydraulic loop and preventing road conditions from damaging the hydraulic system.

5.2 Overall steering control scheme

The structure of the modified model experiment vehicle platform can be divided into a navigation positioning and orientation system, an upper computer control system, a lower computer hydraulic steering unit, a gyroscope angle sensor feedback unit and the like, as shown in fig. 25. The positioning satellite navigation system adopts a GPS satellite receiving system, positioning data adopts a carrier phase difference technology, and the precision of a moving state reaches 2 cm. And the upper computer navigation system obtains the position, speed and course information of the agricultural vehicle according to the navigation positioning system, and decides the front wheel steering angle required by the current model vehicle through a certain algorithm. And the steering system of the lower computer feeds back the steering angle information of the current vehicle in real time through an angle sensor arranged on the front wheel. Meanwhile, the steering angle of the front wheel is compared with the steering angle of the front wheel decided by the upper computer, and stable, quick and accurate response to the steering angle is realized through a certain hydraulic driving algorithm.

5.3 Curve self-adjusting PID course tracking algorithm

5.3.1 Curve tracking problem analysis

When the automatic driving vehicle turns at the boundary of the farmland, the transverse error is increased because the speed is greatly changed, and the general control method is not used any more. Course tracking is a basic method for path tracking of autonomous agricultural vehicles. In this method, both the position deviation and the heading deviation can be converted into a heading deviation. Therefore, accurate heading tracking is a prerequisite for implementing turn tracking. The steering system of the automatic driving agricultural machine is a complex nonlinear system, the steering process is delayed, accurate simulation is difficult to carry out by using a mathematical model, and in the course tracking process, the change of parameters in the system model has obvious influence on the tracking effect, for example, when the agricultural machine steers at the boundary of a farmland, the driving speed of the agricultural machine is reduced, and the course tracking effect is inevitably influenced.

In the past, only the deviation between the expected course deviation of the agricultural machine and the current course is generally considered for the research on the course tracking control problem of the automatic driving agricultural machine vehicle, and because the agricultural machine course is closely related to the traveling speed of the agricultural machine, the steering angle of a front wheel, the slip ratio of tires and the like, the important influence factors are not considered and influence the course tracking effect of the agricultural machine. Therefore, in the agricultural machinery steering process, when the key control parameters of the steering system are changed, the system needs to be reset.

A general PID control method is used for designing an agricultural machinery course tracking controller, proportional, integral and differential parameters of the PID controller are set according to a certain determined running speed of an agricultural machinery, but when the running speed of the agricultural machinery is slightly changed, the PID parameters need to be set again. Otherwise, the regulation performance of the agricultural machinery steering system is damaged, the system is overshot, and the phenomenon of large vibration occurs. In the actual operation process of the agricultural machine, the control method specifically shows that the agricultural machine can better realize turning or sharp turning control at a certain speed, and once the speed of the agricultural machine changes, the course tracking has larger deviation or frequent oscillation. Based on the above analysis, since the speed of the agricultural machine significantly changes when the agricultural machine turns in the field, the heading tracking controller must consider the problem of self-adjustability of the travel speed of the agricultural machine.

5.3.2 course estimation algorithm principle

In the process of controlling the agricultural machine to turn at the boundary of the farmland, the course tracking controller outputs the control quantity to the hydraulic steering mechanism through a navigation control algorithm according to the difference value between the current agricultural machine course angle and the expected course angle so as to finish steering. Because the hydraulic steering mechanism has the characteristic of delayed response when executing the steering operation, when the executing mechanism starts to steer, the actual course of the moving agricultural machine is changed at the moment, and the course tracking has corresponding errors by continuously executing the original steering control quantity.

The course tracking and predicting algorithm principle is to predict the course of the automatic driving agricultural machinery at each moment, obtain the estimation of the movement course change of the agricultural machinery, and feed back the predicted course deviation as a control quantity to the tracking controller, so that the output of the steering system, namely the steering angle of the front wheels can reflect the trend of the course change, and the influence brought by the response delay of the system is reduced. The adopted heading prediction algorithm is based on a simplified agricultural machinery dynamic model, the heading prediction model is shown in figure 26, and R in the figure represents the radius of the unmanned vehicle moving around the movement center point O.

In the course tracking process of the automatic driving agricultural vehicle, the course angular speed of the agricultural machine can be solved according to the agricultural machine constraint condition, the change rate of the course deviation of the agricultural machine can also be obtained, and the course angular change value of the automatic driving agricultural vehicle in a control cycle time can also be obtained by the product of the course deviation change rate and the control cycle. Setting the time of one control period of the agricultural machinery course tracking controller as T, and the speed of the front wheel of the agricultural machinery as the longitudinal speed of the agricultural machinery, so as to obtain the course variable quantity of the automatically driven agricultural machinery vehicle in the time of one control period T:

the radius of the front wheel about the center of motion can be given by:

it is possible to obtain:

in the formula, the front wheel deflection angle f is measured by a gyroscope angle sensor in a sampling period at the current moment, and a certain change occurs in the next control period, but Δ ψ obtained by derivation from the continuity of the speed and the steering angle change is feasible as the heading change estimator of the automatically driven agricultural vehicle in the next control period. And delta psi is the estimated variation of the unmanned agricultural machine heading, and the estimated variation is the variation in a system control period. When a course tracking controller is designed, the sum of the course at the current moment and the heading pre-estimated quantity is used as the system feedback quantity when the agricultural machinery control feedback quantity is considered, and the input deviation of the controller is the difference value between the expected course and the course pre-estimated quantity. The heading tracking controller system structure is shown in fig. 27.

On the realization of course tracking algorithm, an incremental PID calculation method is selected and used, and the proportional, integral and differential parameter coefficients of the PID controller are the same.

5.3.3 simulation study

Under the condition of building a simulation environment in Matlab/Simulink, a system simulation structure chart is built according to an actual agricultural machinery steering system, as shown in FIG. 28. And respectively verifying the course tracking performance and the path tracking.

Setting the initial course deviation as 20 degrees, taking the speed as 1m/s during simulation, and respectively showing course step response curves of course pre-estimates.

From the results shown in fig. 29 and fig. 30, it can be seen that the response result obtained by the heading estimation control method of the control algorithm at the longitudinal speed of 1m/s is better than that obtained by the general control method. The tracking process is relatively stable, and the tracking controller shows higher robustness.

The initial path deviation of the automatic driving agricultural vehicle is set to be-1 m, the initial course deviation is 0, and the longitudinal speed is 1.5m/s during simulation. And comparing results of the conventional method and the course estimation method during simulation. The position deviation step response curve of the path tracing is shown in fig. 31:

the simulation results shown in fig. 32 show that the tracking control algorithm has smoother step response than the general control algorithm by using the course estimation, and also has better adaptability when the longitudinal speed increases and changes, the stability of the course estimation control method and the adaptability to the longitudinal speed are obviously better than those of the conventional method, and the course estimation tracking algorithm is suitable for being used when the agricultural machinery realizes steering at the field boundary.

6. Intelligent agricultural machinery experiment

According to the demand of intelligent agricultural machinery field operation, a whole set of agricultural machinery automatic driving control method comprising optimization-based path planning real-time control is provided by considering a dynamics model and a kinematics model of the agricultural machinery, combining related theories and technologies and applying theories and methods of intelligent control and optimization. In order to verify the practical performance of the automatic driving control method of the agricultural machine under the unmanned driving condition, the experiment of automatic driving of the agricultural machine is carried out on the intelligent pesticide spraying machine platform. A path optimization and real-time control method through simulation inspection is comprehensively applied to an experimental platform.

The experiment is carried out on a 3000-type intelligent pesticide spraying machine platform modified by machinery manufacturing limited company in Shandong, the same continent, Shandong, the control system of the agricultural machine calculates the deviation of the position and the direction in the automatic driving process according to the data obtained by a GPS navigation system on the agricultural machine, the control method is installed according to the deviation to solve the target steering wheel corner, and the target steering wheel corner is input into a vehicle-mounted control system on the agricultural machine in a communication mode, so that the agricultural machine can automatically track the target path. The general principle of the control system is shown in fig. 32.

In the experiment, after the agricultural machine is started, a hand throttle is fixed, a target straight path is tracked at the speed of about 2m/s, and information such as the position, the speed and the target steering wheel rotation angle of the agricultural machine at the sampling time point is recorded on the upper computer and used for evaluating the performance of the control method.

In the experiment, a plurality of tracking experiments are carried out in a farmland, and the tracking length is about 100 m. And in the tracking process, the position, the speed and other data of the intelligent agricultural machine are measured through the navigator and the comprehensive inertial navigation system. The intelligent agricultural machinery driving path and the error change obtained according to the experiment are shown as follows:

the experimental result of the intelligent agricultural machinery tracking target shows that: the intelligent agricultural machine can complete basic operation path tracking tasks. The maximum deviation of the straight line tracking deviation of the agricultural machinery in the path tracking process of 100m is about 0.02 m. The tracking precision of the agricultural machinery for straight-line running is high, the tracking error can be kept in a small range, and the task of straight-line running can be effectively completed.

In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When used in whole or in part, may be implemented in a computer program product comprising one or more computer instructions. When loaded or executed on a computer, cause the flow or functions according to embodiments of the invention to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored on a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website site, computer, server, or data center to another website site, computer, server, or data center via wire (e.g., coaxial cable, fiber optics, Digital Subscriber Line (DSL), or wireless (e.g., infrared, wireless, microwave, etc.)). The computer readable storage medium can be any available medium that can be accessed by a computer or a data storage device including one or more available media integrated servers, data centers, and the like. The usable medium may be a magnetic medium (e.g., floppy Disk, hard Disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. The intelligent pesticide spraying agricultural machine path finding navigation control method is characterized by comprising the following steps of:

2. The intelligent agricultural machinery way-finding navigation control method for pesticide spraying as claimed in claim 1, wherein in the second step, the agricultural machinery navigation positioning information includes, but is not limited to, longitude and latitude, UTC time, ground speed, ground heading, roll angle, pitch angle, positioning accuracy of the agricultural machinery position.

3. The intelligent agricultural machinery path-finding navigation control method for pesticide spraying of claim 1, wherein in the second step, the accurate navigation and positioning method for the agricultural machinery comprises the following steps:

4. The intelligent agricultural machinery path-finding navigation control method for pesticide spraying of claim 1, wherein in the third step, the path planning method comprises:

(1) establishing a farmland environment model by adopting a grid method:

firstly, a farmland area is represented by grids, the grids without obstacles are called barrier-free grids, the grids with obstacles are called barrier grids, and the size of each unit grid is determined according to the motion state of the agricultural machinery; obtaining position information of beacon nodes in a farmland through an RTK-GPS (real time kinematic-GPS); determining the basic shape of the farmland through the position coordinates of the beacon nodes arranged on the farmland corners and the boundaries, and determining the position coordinates of the obstacles in a plane coordinate system of the farmland according to the relative positions of the obstacles in the farmland and the farmland corners and the boundaries; obtaining a farmland grid map;

the sequence number method: performing decimal numbering on all grids from left to right and from bottom to top;

the operation width is the distance between two adjacent straight paths in the operation process of the agricultural machine, under the condition that the operation width is smaller than the turning diameter, the agricultural machine turns according to three sections of circular arc paths, at the moment, the agricultural machine needs to be adjusted in the opposite direction of the next operation straight line firstly, then turns, and completes the agricultural machine operation path according to the turning strategy;

5. The intelligent agricultural machinery way-finding navigation control method for pesticide spraying of claim 1, wherein the intelligent agricultural machinery way-finding navigation control method for pesticide spraying further comprises:

when path planning is executed, planning an optimal route entering a target path for the agricultural machinery according to the current position, speed, driving direction related information of the agricultural machinery and the information of the target path;

6. The intelligent agricultural machinery path-finding navigation control method for pesticide spraying of claim 5, wherein the agricultural machinery path planning and real-time tracking method comprises the following steps:

the dynamic model of the linear tracking process is as follows:

the dynamic model of the turning process comprises:

7. an intelligent agricultural machinery path-finding navigation control system for pesticide spraying, which implements the intelligent agricultural machinery path-finding navigation control method for pesticide spraying according to claim 1, is characterized in that the intelligent agricultural machinery path-finding navigation control system for pesticide spraying comprises:

a navigation module: the system comprises an industrial personal computer unit, a GPS navigation unit and a visual navigation unit, and is used for carrying out accurate navigation positioning by utilizing a GPS navigation and carrier phase differential technology, namely RTK (real-time kinematic) to acquire related navigation data;

a vehicle-mounted control module: the agricultural machinery executing mechanism is controlled to run according to the planned path by the vehicle-mounted controller based on the running data, the related planned path and the control target, so that automatic navigation and running control of the agricultural machinery are realized;

8. The intelligent agricultural machinery of claim 7, wherein the navigation module comprises:

the visual navigation unit consists of a camera and an image processing module;

the agricultural machinery actuating mechanism includes:

a safety valve: for controlling the oil pressure of the hydraulic circuit;

a balance valve: for ensuring the pressure of the hydraulic circuit;

9. An information data processing terminal for realizing the intelligent pesticide spraying agricultural machinery way-finding navigation control method according to any one of claims 1 to 6.

10. A computer-readable storage medium comprising instructions which, when executed on a computer, cause the computer to execute the intelligent agricultural machinery way-finding navigation control method of pesticide spraying according to any one of claims 1 to 6.