CN-119148756-B - Unmanned agricultural machinery limited time output feedback control method and control equipment under unknown course information

CN119148756BCN 119148756 BCN119148756 BCN 119148756BCN-119148756-B

Abstract

The invention discloses a finite time output feedback control method and control equipment for an unmanned agricultural machine under unknown course information, and belongs to the field of unmanned agricultural machine path tracking control. Under the method, the unmanned aerial vehicle can accurately track the target of the reference path in a limited time. The method mainly comprises the steps of 1, based on an unmanned agricultural machinery kinematics model, taking disturbance items into consideration, constructing a deviation model, converting the deviation model into a state space equation, 2, designing a state observer to observe a state variable containing course information, and 3, based on the state observer, designing a finite-time output feedback controller to realize path tracking control. The invention has the advantages of firstly considering disturbance in the deviation model to improve the accuracy of the model, secondly constructing a state observer to observe the state variable containing the heading information and ensuring the stability of the system when the heading information is not measurable, and thirdly designing a finite time output feedback path tracking control method to ensure the finite time convergence of tracking errors.

Inventors

LIU LU
YANG WENHAO
DING SHIHONG
MA LI
XIA HUI

Assignees

江苏大学

Dates

Publication Date: 20260512
Application Date: 20240903

Claims (7)

1. The unmanned agricultural machinery limited time output feedback control method under the condition of unknown course information is characterized by comprising the following steps: step 1, based on an unmanned agricultural machinery kinematics model, introducing disturbance related to transverse deviation and heading deviation, constructing an unmanned agricultural machinery deviation model, and converting the model into a state space equation; In the step 1, the unmanned agricultural machinery deviation model is established as follows: Wherein, the Is the steering coefficient; 、 disturbances associated with lateral and heading bias, respectively; Assuming that the agricultural machine is always travelling forward and following the reference path in a clockwise direction, i.e Based on the deviation model, a state variable is selected The state space equation is constructed as follows: Wherein, the Is a state vector of the agricultural machinery path tracking system, , In order to control the variables of the plant, Representing the lumped disturbance; Wherein, the Is the longitudinal running speed of the unmanned agricultural machinery; is the wheelbase of unmanned agricultural machinery; is the lateral deviation; Is the heading deviation; Is the desired heading angle; is the steering angle of the front wheels of the unmanned agricultural machinery; Step2, considering the condition that the course information is not measurable, constructing a state observer to observe a state variable containing the course information; And 3, designing and obtaining a finite time output feedback controller based on the state observer constructed in the step 2 according to a finite time Lyapunov control theory, wherein the finite time output feedback controller is as follows: Wherein, the It is the control gain that is used to control the gain, Is a positive function of the number of the elements, Is a function of Lower limit of (2) satisfies At the moment, the agricultural machinery path tracking control is realized by constructing an output feedback controller and using only the transverse deviation; step 4, designing the parameter self-adaption rate of the controller; In the step 4, the adaptive rate is designed as follows: Will control the gain Designed as time-varying gain The method comprises the following steps of: Wherein, the Is a time-varying gain Is used as a starting point of the (c) for the (c), As an auxiliary variable, the number of the auxiliary variables, And Is of a smaller value, is introduced into The purpose of (a) is to ensure adaptive parameters Positive values; Step 5, combining the self-adaptive rate with a limited time output feedback controller to obtain the self-adaptive limited time output feedback controller, and carrying out inverse transformation on the controller to obtain the front wheel rotation angle required by the agricultural machinery; And step 6, transmitting control signals including the speed of the agricultural machinery and the front wheel rotation angle of the agricultural machinery obtained in the step 5 to a whole agricultural machinery controller to realize path tracking control of the agricultural machinery.
2. The method for controlling finite time output feedback of unmanned agricultural machinery under unknown course information according to claim 1, wherein in the step 1, the unmanned agricultural machinery is front wheel steering rear wheel driving, and the kinematic model is as follows: Wherein, the Is the position coordinate vector of the unmanned agricultural machinery; is the longitudinal running speed of the unmanned agricultural machinery; Is a course angle; is the wheelbase of the unmanned agricultural machinery, namely the distance from the center of the front wheel to the center of the rear wheel; is the steering angle of the front wheels of the unmanned agricultural machinery.
3. The method for controlling the limited time output feedback of an unmanned agricultural machine under unknown heading information according to claim 2, wherein in said step 1, said lateral deviation Is defined as the distance between the current position point of the agricultural machine and the nearest point on the reference path, and the course deviation Defining a difference value between the current course angle and the expected course angle of the agricultural machine; The specific formula is as follows: Wherein, the Is the position coordinate vector of the reference point; Is the current position coordinate vector of the agricultural machinery; The current course angle of the agricultural machinery; is the desired heading angle.
4. The method for controlling the limited time output feedback of the unmanned agricultural machinery under the unknown heading information according to claim 1, wherein in the step 2, the state observer is configured to: Wherein, the Is an intermediate variable which is used to control the flow of water, All are positive functions; is a state variable Is a function of the estimated value of (2); functions in the state observer The value of (2) is required to meet Under the above relation, the observation error can be ensured Converging to zero for a finite time.
5. The method for controlling the limited time output feedback of the unmanned agricultural machinery under the unknown heading information according to claim 1, wherein in the step 5, the adaptive limited time output feedback controller is designed as follows: Wherein, the Is an adaptive control gain; to the controller Performing inverse transformation to obtain the front wheel steering angle required by agricultural machinery 。
6. The method for controlling the limited time output feedback of the unmanned agricultural machinery under the unknown course information according to claim 1, wherein the specific implementation of the step 6 comprises the following steps: The CAN bus ID adopts an extended ID, the CAN format adopts an Intel format, a CAN communication message matched with the unmanned agricultural machinery is designed, and a data transmission module is utilized to transmit a control signal to the agricultural machinery whole vehicle controller through the CAN bus, so that the path tracking control of the agricultural machinery is realized.
7. The control device for the unmanned agricultural machinery is characterized by comprising an information processing module, a data receiving module and a data sending module, wherein the information processing module can realize the content of the steps 1-5 according to any one of claims 1-6 based on the data receiving module receiving the unmanned agricultural machinery position information from the Beidou positioning system, and the data sending module can realize the content of the step 6 according to any one of claims 1-6.

Description

Unmanned agricultural machinery limited time output feedback control method and control equipment under unknown course information Technical Field The invention belongs to the field of unmanned agricultural machinery path tracking control, and relates to a finite time output feedback control method and control equipment for an unmanned agricultural machinery under unknown course information. Background Agricultural machinery is an important foundation for modern agricultural development and is also an important sign of agricultural modernization. The degree of agricultural mechanization and automation is one of the important factors affecting the agricultural production efficiency and productivity. It is worth mentioning that the autonomous navigation technology is of vital importance in agricultural operation scenes such as rotary tillage, planting, pesticide application, harvesting and the like, and mainly comprises three parts of farmland environment sensing, operation task decision and path planning and agricultural machinery path tracking control. Among them, the high-precision and stable agricultural machinery path tracking control is a key technology to be solved. The above technique relies on a reliable high precision positioning system and attitude sensor, and a control algorithm that can achieve fast convergence with small steady state errors. Notably, the Beidou RTK system can provide centimeter-level positioning accuracy, is used for measuring the position information of the agricultural machinery, and calculates the transverse deviation between the position information and the reference path. On the other hand, heading information is usually dependent on an inertial measurement unit, and it has a problem that zero drift often occurs. Under the influence of the bias of an Inertial Measurement Unit (IMU) and the change of an input/output scale factor, the measurement error of a heading angle can be increased along with the accumulation of time, so that the tracking precision is poor and even unstable conditions occur, and the requirement of long-time high-efficiency operation of an unmanned agricultural machine is difficult to meet. In addition, the cost of the high precision IMU/RTK combination system is also very high. It is therefore very interesting to design a state observer that can estimate the information containing heading. In unstructured farmland environments, internal and external disturbances in the agricultural machine path-tracking system are caused by agricultural machine modeling uncertainties, as well as the presence of rough road surfaces, and the like. The existing path tracking control method such as PID control, stanley control, fuzzy control, model prediction control and the like are difficult to realize limited time convergence, and an agricultural machine path tracking system has higher requirements on convergence time, so that a control method capable of realizing limited time convergence needs to be designed. Therefore, the invention designs the unmanned agricultural machinery limited time output feedback control method based on the state observer capable of observing the heading information, so that when the heading information is not detectable, the transverse deviation can be converged to zero for a limited time, and the rapidity and the steady-state performance of the unmanned agricultural machinery are ensured. Disclosure of Invention In order to realize limited time convergence of an agricultural machinery path tracking control system under the condition that navigation information is not measurable, and simultaneously has good anti-interference performance and steady-state performance, the invention provides an unmanned agricultural machinery limited time output feedback control method under unknown navigation information, which comprises the following steps: step 1, based on an unmanned agricultural machinery kinematics model, introducing disturbance related to transverse and course deviation, constructing an unmanned agricultural machinery deviation model, and converting the model into a state space equation; step 2, considering the condition that the course information is not measurable, constructing a state observer to observe a state variable containing the course information, and improving the stability and tracking precision of the tracking system; Step 3, designing and obtaining a finite time output feedback controller based on the state observer constructed in the step 2 according to a finite time Lyapunov control theory; step 4, designing the parameter self-adaption rate of the controller; Step 5, combining the self-adaptive rate with a finite time output feedback control method to obtain a self-adaptive finite time output feedback controller, and performing inverse transformation on the controller u=ta n δ to obtain a front wheel rotation angle δ (t) =arctanu (t) required by the agricultural machinery; And 6, constructing a data transmission module acc