CN-122018314-A - Error tracking-based four-rotor unmanned aerial vehicle full-drive designated time control method

CN122018314ACN 122018314 ACN122018314 ACN 122018314ACN-122018314-A

Abstract

A four-rotor unmanned aerial vehicle full-drive specified time control method based on error tracking belongs to the technical field of unmanned aerial vehicle flight control, and comprises the steps of firstly establishing a rigid body model of a four-rotor unmanned aerial vehicle system, initializing states and control parameters of the system, converting the model into a full-drive system, realizing decoupling of a control channel, secondly constructing a monotone expected error curve, converting the error system model, planning a system error convergence track, further designing a smooth time-varying gain function of an index-polynomial combination, designing a virtual controller, constructing a specified time expansion state observer to estimate internal and external total disturbance, and finally designing a specified time controller based on the expected error curve. The method can ensure that the position and posture tracking errors of the quadrotor unmanned aerial vehicle are converged to the minimum neighborhood near the origin in the preset time, has extremely strong robustness to disturbance, and realizes the track tracking with high precision, strong robustness and excellent transient performance.

Inventors

XIE SHUZONG
CHEN JUNYU
HOU BEIPING
DONG JIANWEI
XIAO LIYANG

Assignees

浙江科技大学

Dates

Publication Date: 20260512
Application Date: 20260126

Claims (6)

1. The four-rotor unmanned aerial vehicle full-drive specified time control method based on error tracking is characterized by comprising the following steps of: Step 1, a rigid body model of a four-rotor unmanned aerial vehicle system is established, the state and control parameters of the system are initialized, and the model is converted into a full-drive system, so that decoupling of a control channel is realized; step 2, constructing a monotonic expected error curve and converting an error system model, and planning a system error convergence track; Step 3, designing a smooth time-varying gain function of the index-polynomial combination, designing a virtual controller, and constructing an observer of a specified time expansion state to estimate total internal and external disturbance; And 4, designing a specified time controller based on the expected error curve.
2. The four-rotor unmanned aerial vehicle full-drive specified time control method based on error tracking as claimed in claim 1, wherein the process of the step 1 is as follows: 1.1 Considering the influence of external interference, the rigid body model of the quadrotor unmanned aerial vehicle is expressed as: (1); Wherein, the Representing the position of the quadrotor unmanned aerial vehicle relative to an inertial coordinate system; Is that Is a derivative of (2); Is that Is a second derivative of (2); Representing the attitude angle of the quadrotor unmanned aerial vehicle relative to an inertial coordinate system; Is that Is a derivative of (2); Is that Is a second derivative of (2); Respectively representing the mass and the gravitational acceleration of the quadrotor unmanned aerial vehicle; Respectively represent the four rotor unmanned aerial vehicle at Moment of inertia on the shaft; Representing aerodynamic coefficients; Representing an external environment uncertainty disturbance in the position and attitude directions; the control input is a four-rotor unmanned aerial vehicle; Representing the control moment of the four-rotor unmanned aerial vehicle; 1.2 Defining virtual control variables for a quad-rotor unmanned helicopter : (2); (3); (4); The rigid body model of the four-rotor unmanned aerial vehicle can be rewritten into a full-drive system model: (5); Wherein, the The position and attitude angle of the four-rotor unmanned aerial vehicle are; Is that Is a derivative of (2); Six control inputs are provided for the four-rotor unmanned aerial vehicle; unmanned aerial vehicle with four rotors internal unmodeled dynamics; representing a bounded external environment uncertainty disturbance; Sum of internal unmodeled dynamics and external total perturbation; 1.3 Define quad-rotor unmanned helicopter tracking error The method comprises the following steps: (6); Wherein, the The track is expected for the four-rotor unmanned aerial vehicle.
3. The four-rotor unmanned aerial vehicle full-drive specified time control method based on error tracking according to claim 1, wherein the process of the step 2 is as follows: 2.1 Constructing a monotonic expected error curve The method comprises the following steps: (7); Wherein, the Representing a specified convergence time constant In the time-course of which the first and second contact surfaces, The specific formula is as follows: (8); Wherein the method comprises the steps of ; The initial value of the tracking error of the four-rotor unmanned aerial vehicle; 2.2 Define four rotor unmanned aerial vehicle expected tracking error The method comprises the following steps: (9); Deriving the formula (9), and substituting the formula (5) to obtain: (10); (11); Wherein, the Respectively represent First and second derivatives of (a); Respectively represent First and second derivatives of (a).
4. The error tracking-based four-rotor unmanned aerial vehicle full-drive specified time control method of claim 1, wherein the process of step 3 is as follows: 3.1 Constructing an exponential-polynomial time-varying gain function as follows To ensure convergence and smooth transitions at specified times: (12); Wherein, the Is a positive parameter; 3.2 The specified time extended state observer is constructed to estimate the internal unmodeled dynamics and the external total perturbation: (13); Wherein, the Is that Is a function of the estimated value of (2); Is that Is a derivative of (2); Is the extended state observer gain variable; 3.3 Defining a specified time extended state observer error The method comprises the following steps: (14); deriving the formula (14), and substituting the formula (5) and the formula (13) to obtain: (15); Wherein, the Is a Hulvitz matrix; is a constant matrix; Is the actual total disturbance; 3.4 Defining virtual errors The method comprises the following steps: (16); Wherein, the Is that Is a derivative of (2); for the virtual control rate, the design is as follows: (17); Wherein, the Gain for the virtual controller; 3.5 Deriving a virtual error to obtain: (18)。
5. The error tracking-based four-rotor unmanned aerial vehicle full-drive specified time control method of claim 1, wherein the process of step 4 is as follows: Designing a time-designated controller based on a desired error curve The method comprises the following steps: (19); Wherein, the Gain for the controller.
6. The four-rotor unmanned aerial vehicle full drive specified time control method based on error tracking according to one of claims 1 to 5, wherein the method further comprises the following steps: Step 5, the stability of the observer and the controller in the appointed time expansion state is proved, and the process is as follows: 5.1 Based on the inversion recursion idea, the first step designs the following lyapunov function, proving that the specified time extended state observer stably converges: (20); Wherein, the Is a positive definite matrix; deriving the formula (20), and obtaining: (21); Wherein, the ; Is that Maximum value of (i), i.e ; Is a positive definite matrix; 5.2 Based on the inversion recursion idea, the second step designs the following lyapunov function, proving stable convergence of the controller at the specified time based on the expected error curve: (22); Deriving the formula (22), and obtaining: (23); Wherein, the ; Representing and taking the minimum values of the three; Is that Maximum value of (i), i.e ; Based on the above analysis, it is shown that the extended state observer and tracking error at the specified time can not only converge rapidly in the specified time, but also converge stably into a small neighborhood.

Description

Error tracking-based four-rotor unmanned aerial vehicle full-drive designated time control method Technical Field The invention belongs to the technical field of unmanned aerial vehicle flight control, and provides a four-rotor unmanned aerial vehicle full-drive specified time control method based on error tracking aiming at underactuated characteristics, external environment interference and internal unmodeled dynamics existing in a four-rotor unmanned aerial vehicle system and the system has strict convergence time requirements. Background The four-rotor unmanned aerial vehicle has been widely applied to complex tasks such as logistics transportation, disaster rescue, agriculture and forestry plant protection, military reconnaissance and the like due to the characteristics of simple structure, strong vertical take-off and landing capability, flexibility and the like. With the increasing complexity of application scenes, the performance requirements of the four-rotor unmanned aerial vehicle control system are not limited to simple hovering or low-speed flight, and more severe indexes are provided for the rapid track tracking capability, the strong anti-interference capability and the timeliness of completing tasks within a specified time of the system. However, quad-rotor drones are a typical under-actuated, strongly coupled, nonlinear system. On one hand, the unmanned aerial vehicle has only four control inputs, but needs to control six degrees of freedom, so that a system dynamics equation is highly coupled, great difficulty is brought to the design of the controller, on the other hand, in the actual flight process, the unmanned aerial vehicle is inevitably interfered by external environments such as gusts, air flow disturbance and the like, and meanwhile, the unmanned aerial vehicle has internal unmodeled dynamics such as load change, inaccurate pneumatic parameters and the like. These internal and external disturbances severely impact flight stability, making high-precision tracking control a serious challenge. Traditional four-rotor unmanned aerial vehicle control methods, such as PID control, backstepping and sliding mode control, are mostly based on asymptotic stability theory. Although these methods are widely used in engineering, in theory, the time required for the system state to converge to the equilibrium point tends to be infinite, and it is difficult to meet the requirements of emergency rescue or tactical battle tasks with extremely high requirements on timeliness. In order to increase the convergence speed, finite time and fixed time control theory is introduced into the drone control. While fixed time control ensures that there is an upper bound on convergence time that is independent of the initial state, the upper bound often depends on a complex combination of controller parameters, making it difficult to set the exact convergence time directly with a simple parameter, resulting in a "trial and error" dilemma for the designer in actual debugging. The full-drive system method which is proposed in recent years provides a new view for solving the control problem of the underactuated system, and a high-order nonlinear system is converted into a linear system with full-drive characteristics through model conversion. At the same time, the specified time control theory allows the user to directly specify the physical time constant. However, the existing combination method still has the defects that firstly, in order to achieve convergence at the designated time, the traditional method often needs infinite control gain at the terminal moment, so that gain explosion is caused, saturation and even damage of an actuating mechanism are easy to occur, secondly, a conventional observer is difficult to accurately estimate complex disturbance in the designated time, and in addition, excessive overshoot is possibly caused due to lack of quantitative planning of transient errors in the track tracking process. In view of the foregoing, there is a need in the current unmanned aerial vehicle control field for a control scheme that can solve the under-actuated coupling problem by a full-drive system method, achieve convergence of a specified time set by a user, effectively compensate for total disturbance by using an observer, and ensure smoothness and bouncy of control instructions. The present invention has been made in view of the above-mentioned background and technical problems. Disclosure of Invention The invention provides a four-rotor unmanned aerial vehicle full-drive appointed time control method based on error tracking, which aims to solve the problems that in the prior art, the four-rotor unmanned aerial vehicle is difficult to meet the requirements of appointed time convergence, high-precision anti-interference and control input smoothness under underactuated constraint and complex disturbance. The method comprises the steps of firstly establishing a rigid body model of the four-rotor unmanned