CN109765907B

CN109765907B - PID model-free self-adaptive course control algorithm for ships

Info

Publication number: CN109765907B
Application number: CN201910163383.7A
Authority: CN
Inventors: 廖煜雷; 李晔; 姜权权; 成昌盛; 武皓微; 潘恺文; 张铁栋; 王卓
Original assignee: Harbin Engineering University
Current assignee: Harbin Engineering University
Priority date: 2019-03-05
Filing date: 2019-03-05
Publication date: 2022-04-05
Anticipated expiration: 2039-03-05
Also published as: CN109765907A

Abstract

The invention belongs to the field of ship motion control, and particularly relates to a PID model-free self-adaptive course control algorithm for ships. Introducing a self-adaptive proportional term and a self-adaptive differential term into a model-free self-adaptive control algorithm, and providing a PID-MFAC algorithm for ships; according to the expected course y of the ship^*(k) Calculating course deviation e (k) and e (k) y with the current course y (k) of the ship^*(k) -y (k); when the absolute value | e (k) | of e (k) is less than the set threshold value e of heading state deviation₁If the actual course of the ship is converged to the expected course, jumping out of the loop, otherwise executing the next step; solving the expected input u (k) of the heading system by a PID-MFAC algorithm according to e (k); the control mechanism receives and executes a heading system input command u (k); and (5) making k equal to k +1, updating the current heading y (k) of the ship, and going to the step 2. The invention solves the problems that the MFAC algorithm is directly applied to the ship course control and is easy to generate serious overshoot, oscillation phenomena and even instability, and the introduction of the adaptive proportional term and the adaptive differential term improves the response speed of the controller and the dynamic response performance of the system.

Description

PID model-free self-adaptive course control algorithm for ships

Technical Field

The invention belongs to the field of ship motion control, and particularly relates to a PID model-free self-adaptive course control algorithm for ships.

Background

The ship course can be accurately controlled, so that the ship can safely and effectively execute various tasks, such as chart drawing, hydrological measurement and the like. In engineering application, the course control of ships is basically realized by adopting a PID control algorithm, but the ships are easily affected by perturbation of a model, environmental interference and the like, so that a PID controller with a set of fixed parameters is difficult to maintain a consistent control effect, and the system can be stabilized only by readjusting the parameters. The controller developed based on the model-oriented design strategy seriously depends on a system mathematical model, and because the accurate mathematical model is very difficult to obtain, the self-adaption of the system is poor due to the influence of unmodeled dynamics, model perturbation and the like, and the robust performance of the system is difficult to ensure, so that the controller is difficult to be applied in engineering.

In the document "Heading MFA control for unified surface vehicle with angular velocity Heading", the authors propose a cascade control method to indirectly control the Heading of an unmanned ship by means of angular velocity guidance. However, the structure of the controller is complex, and the multi-parameter setting of the parameters of the controller is difficult. On application date 2018, 09 and 5, application number 201811031878.6, the invention name "integral separation type PI type compact format model-free control method for ships" realizes the purpose of controlling the ship course by combining proportional control and a compact format model-free self-adaptive method, but the proportional control has no self-adaptability. On application date 2018, 02/02, application number 201810106120.8, entitled "a redefined output model-free adaptive course control method and system", the purpose of controlling the ship course is achieved by redefining the system output into the linear sum of the ship course and the angular velocity. However, in practice, the angle information of the ship is not easy to obtain, and the angular velocity information is inaccurate to measure due to the existence of external interference, so that the method is not easy to implement in engineering.

Disclosure of Invention

The invention aims to provide a PID model-free self-adaptive course control algorithm for a ship, so that the course of the ship can be stably converged to a desired course.

A PID model-free self-adaptive course control algorithm for ships comprises the following steps:

step 1, introducing a self-adaptive proportional term and a self-adaptive differential term into Model Free Adaptive Control (MFAC), and providing a PID-MFAC algorithm for ships;

step 2, calculating a heading deviation e (k) according to the expected heading y (k) of the ship and the current heading y (k) of the ship, wherein e (k) y^*(k)-y(k)；

Step 3, comparing the absolute value of e (k) with e₁When the absolute value | e (k) | of e (k) is less than the set threshold value e of heading state deviation₁If not, executing a PID _ MFAC algorithm, and solving the course system expected input quantity u (k) by the PID-MFAC algorithm;

step 4, the control mechanism receives and executes a course system input instruction u (k);

and 5, enabling k to be k +1, updating the current course y (k) of the course ship, and going to the step 2.

The PID model-free self-adaptive course control algorithm for the ship has the form of a self-adaptive proportional term in the step 1

The form of the adaptive differential term is

The PID model-free self-adaptive course control algorithm for the ship comprises the following steps in step 2:

wherein, eta ∈ (0, 1)]，ρ∈(0,1]α and β are step factors, μ > 0, λ > 0 are weighting coefficients, Δ e (k) ═ e (k) -e (k-1), e (k) · e (k-1), and e (k-1), respectively(k) heading bias for the kth, control period k-1, u (k) modified PID _ MFAC algorithm output for the kth control period, φ (k) is the pseudo-partial derivative,

for the estimated value of the pseudo partial derivative, when | delta u (k-1) | ≦ epsilon or

Or

When it is used, order

According to the PID model-free self-adaptive course control algorithm for the ship, the step length factor beta, alpha enables the control algorithm to be changed into the following form:

the PID model-free self-adaptive course control algorithm for the ship comprises step 3, namely e₁For smaller normal amounts, take e in the present invention₁＝2。

The invention has the beneficial effects that:

the invention introduces a self-adaptive proportional term and a self-adaptive differential term into Model Free Adaptive Control (MFAC) based on a model free adaptive theory, provides a PID-MFAC algorithm for ships, and solves the problem that the MFAC algorithm is directly applied to ship course control and is easy to cause serious overshoot, oscillation phenomenon and even instability. The introduction of the adaptive proportional term improves the response speed of the controller, and the introduction of the adaptive differential term enables the control algorithm to have a prediction effect on the response of the ship course system, thereby improving the dynamic response performance of the system.

Drawings

FIG. 1 is an overall block diagram of a heading system of the present invention;

FIG. 2 is a flow chart of the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings:

FIG. 1 is a block diagram of a course system according to the present invention; first, give the desired heading y (k)^*According to the actual course y (k) of the ship at the current moment, calculating a course deviation e (k) as an input of a PID-MFAC algorithm, and solving a course system expected input quantity u (k) by the PID-MFAC algorithm. And the control mechanism executes the expected input command u (k) so as to change the actual course of the ship, and the course deviation e (k) is updated by k +1 and serves as the input of the PID-MFAC algorithm at the next moment. And circulating the process so as to converge the actual course of the ship to the expected course.

Fig. 2 shows a flow chart of the system of the present invention. The method comprises the following concrete steps:

step 1, introducing a self-adaptive proportional term and a self-adaptive differential term into Model Free Adaptive Control (MFAC), and providing a PID-MFAC algorithm for ships. The adaptive proportional term is in the form of

The form of the adaptive differential term is

The form of the adaptive differential term is

wherein, eta ∈ (0, 1)]，ρ∈(0,1]Alpha and beta are step size factors, mu is more than 0, lambda is more than 0, is weight coefficient, delta e (k) is e (k) -e (k-1), e (k) and e (k-1) are heading deviation of the k-th and k-1-th control periods respectively, u (k) is output of the modified PID _ MFAC algorithm of the k-th control period, phi (k) is a pseudo partial derivative,

Or

When it is used, order

any method of introducing the step size factor in this form is within the scope of this patent.

Claims

1. A PID model-free self-adaptive course control algorithm for ships is characterized by comprising the following steps:

step 1, calculating course deviation e (k) according to the expected course y (k) of the ship and the current course y (k) of the ship;

e(k)＝y^*(k)-y(k)

step 2, if the absolute value | e (k) | of e (k) is less than the set threshold value e of heading state deviation₁If so, the actual course of the ship is considered to be converged to the expected course, and the step 4 is executed; otherwise, executing a PID _ MFAC algorithm, and solving the expected input quantity u (k) of the heading system by the PID-MFAC algorithm;

the PID _ MFAC algorithm is:

wherein, eta ∈ (0, 1)]，ρ∈(0,1](ii) a Alpha and beta are step size factors; mu is more than 0, and lambda is more than 0 as a weight coefficient; Δ e (k) ═ e (k) — e (k-1), e (k) and e (k-1) are heading deviations of the kth and kth control periods, respectively; u (k) improve the PID _ MFAC algorithm output for the k control period; phi (k) is the pseudo-partial derivative,

when | delta u (k-1) | ≦ epsilonOr

Or

When it is used, order

Step 3, the control mechanism receives and executes a course system input instruction u (k);

and 4, enabling k to be k +1, updating the current course y (k) of the course ship, and going to the step 2.

2. The PID model-free adaptive heading control algorithm for ships according to claim 1, wherein e in step 3 is₁For small normal amount, take e₁＝2。