JPS59195491A - Method of steering ship - Google Patents

Abstract

PURPOSE:To minimize the fuel consumption of a ship, by automatically adjusting the control system parameter of an automatic steering device so that the resistance to which the ship is subjected is made minimum in accordance with an evaluating function value. CONSTITUTION:When a set compass direction PSIr and an actual compass direction PSI of a ship 3 are delivered to a digital computer 1 that computes a steering angle with which the deviation between the PSIr and the PSI is made null. Then a steering angle instruction Rc is fed to a steering unit 2 by which the steering angle R is set. The turning angle PSI' of the ship 3 is fed to a gyrocompass 4 to measure the actual compass direction PSI of the ship 3. This compass direction PSI is fed to the digital computer 1 to be compared with the set compass direction PSIr. Then the above-mentioned steps are successively repeated. With this method a parameter vlue which minimizes an evaluating function value is set to a control system to automatically compensate the parameter value of the control system so that the resistance to which a ship is subjected during the sailing of cource keeping, may be made minimum to minimize the fuel consumption of the ship.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for steering a ship. Conventionally, ships are steered by an autopilot. An autopilot is basically an automatic steering device that performs P'ID operation, and is made up of an automatic steering system with additional nonlinear elements that perform weather adjustment mechanisms and the like.

Many of the parameters of the control system in an automatic steering system are adjusted at the time of shipment from the factory or during sea trials, and after the vessel is put into service, the vessel operator makes appropriate changes to specific parameters in response to changes in sea conditions, weather, etc.

However, it is difficult to manually adjust parameters during operation in response to changes in sea conditions, weather, or ship operating conditions.
There are problems in that it is time-consuming, there is no definitive standard for the adjustment method, and there is no guarantee that the steering condition that can be achieved as a result of the adjustment is optimal.

In order to solve the above problems and always achieve and maintain optimal steering, it is necessary to objectively evaluate the steering condition and automatically adjust the parameters of the control system in the automatic steering system based on this evaluation.

However, there is currently no suitable adjustment method.

From the above-mentioned viewpoint, the present invention provides a steering method that can minimize the resistance experienced by a ship during course keeping.

Parameter value 1) by evaluation function based on.

Evaluation function value J for. is calculated, and then the parameter value P. The evaluation function J+' corresponding to the parameter value P is calculated based on the parameter value P, which is different from the evaluation function value J. and Jl, and the parameter value P that inputs the smallest evaluation function value among Jl. Or change the magnitude of Pl to determine a new parameter value P2, and then
2 to the control system, and the evaluation function value J corresponding to the parameter value P2 is determined by the evaluation function based on the parameter value P2.
2 is calculated, and then the evaluation function value J2 and Jo switch or J
Determine a new parameter value P3 that inputs the minimum evaluation function value among l, and then calculate the evaluation function value J corresponding to the parameter value P in the same manner as in the above case,
Hereinafter, the feature will be completely cured by automatically correcting the parameter values of the control system in the same manner.

This invention will be further explained.

FIG. 1 shows a block diagram of the method of the present invention.
When inputted to ``Operation-sama'', yo! The steering angle that makes the deviation between 1llvfr and T zero is calculated, and the steering angle command R6 is
is given to the steering gear 2, and the steering angle R is set by the steering gear 2. The turning angular velocity of the ship 3 is applied to the gyro compass 4 to measure the actual heading (//) of the ship 3, and this heading T is input to the digital computer 1 and compared with the set heading. This operation is then repeated continuously.

One of the following equations is used to calculate the steering angle command Re (k) at time k calculated by the digital calculator 1.

Rc (k) - Rc (k -1) +, p (-V/
(k)+F(k-1)l ” 1 /T1・e (k)
+Td(I(k) +2F(k-1)-Li1(k-2)
l...(1)) Nobori(k)"" RC(k-1
)+Kp (e (k)-e(k-1)) + 1
, /'r 1 e(k)+Td(e(k)-2e(k
-1)+e(k-2] -(2) However, k time, RC(k) steering angle command at time k, V/(k):
Direction of the ship at time k, e (k): 1 additional road deviation at time k.

(1) Still Kp (proportional gain) in equation (2), Ti (
Integral time) and Td (differential time) are parameters, calculate the evaluation function value corresponding to at least one of these parameter values, set the parameter value that minimizes the evaluation function value in the control system, Make the ship go 1iilc economically. In other words, fuel consumption can be reduced by minimizing the resistance that the ship receives during course keeping (when the ship moves straight in a certain direction).

The evaluation function is shown in the following equation.

However, R(k) is the steering angle at time k (approximately the above (
R6(k) in equation 2) may also be used. ), λ゛preference coefficient, N: evaluation time (number of samples), ko, evaluation start time.

Whether a ship can navigate economically or not can be quantitatively evaluated based on the magnitude of the evaluation function value J. In other words, the smaller the evaluation function value J, the higher the longitudinal contiguity during course keeping. In the case of Figure 2, the optimal parameter values are (KP,
T+1) = (KPI + Ta1l) 0 Therefore, if you randomly select multiple combinations of (KP+Td) and calculate the evaluation function value under each condition, you can find the optimal point by trial and error. I can do it. .

Next, a method of finding the above-mentioned optimal point, which is the gist of the present invention, will be explained. In order to simplify the explanation, an example of optimization only for the parameters in equation (1) and equation (2) will be described.

As shown in Figure 3, the parameter KP is changed to a periodic function of a rectangular wave as shown in the following equation.
Period, B bias (B>O), A swing (B>A>O).

Then, the evaluation function values J+ and J- in the first half and the second half of the change in the parameter kp are calculated.

Here, the evaluation function values J+ and J- do not represent the evaluation when the parameter KP is increased or decreased by the number of times relative to the level of the bias value B, respectively.
By comparing the magnitudes of J+ and J- at o+2N, it can be determined whether it is better to increase the bias value B, or to change it or decrease it. .

The correction amount ΔB of the bias value B can be defined by the following equation.

ΔB=C(J--J+)/yrσ, :t(J+,
J'-) - (5) However, C constant (C>O), max (J+, J-) 'Evaluation function value of the larger of ear and J-.

In this way, by correcting No Iasu Tsukuda ■3 by ΔB every cycle, it is possible to automatically obtain the parameter value KP that makes the evaluation function value J the minimum value.

FIG. 4 shows the results of changes in the bias value B of 2 and the evaluation function value J in the parameter values with respect to time kK when the ship is sailed according to the method of the present invention described above.

As is clear from FIG. 4, the bias value B of the parameter value KP converges to a substantially constant value, and the evaluation function value J also decreases accordingly. Therefore, it can be seen that the ship is being steered to navigate economically.

The above is a case in which one parameter value is automatically adjusted, but two or more parameters can be adjusted in the same way.

According to this invention, the parameters of the control system in the automatic steering system can be automatically adjusted so that the resistance to which the ship is subjected is minimized, so the use of fuel 1 can be kept to a minimum. 3゜ which brings extremely useful effects such as

[Brief explanation of drawings]

FIG. 1 is a block diagram of the method of the invention; FIG.
FIG. 3 is a diagram showing the contour value of the evaluation function value when the parameters KP and Td are changed; FIG. 3 is a diagram showing the change in Kp when the parameter KP is changed to a periodic function of a rectangular wave;
FIG. 4 shows the relationship between the bias value B (with respect to time k) and the evaluation function value J. . In the drawings: 1. Digital computing machine 2. Steering machine. 3. Ships 4. Gyroconnox applicant Natsuo Shioya, agent of Nippon Kokan Co., Ltd. (and 2 others)

Claims (1)

[Claims] Parameter value P arbitrarily given to the control system of the automatic steering device. The evaluation function is based on the parameter value P. Evaluation function value J for. is calculated, and then the parameter value P. The evaluation function J corresponding to the parameter value B is calculated based on the parameter value P, which is different from the evaluation function, and then the two evaluation function values J are calculated. and Jl, and a parameter value P that gives the smallest evaluation function value among Jo or J. Or, change the magnitude of p, determine a new parameter value P2, then give the parameter value P2 to the control system, and evaluate the evaluation function corresponding to the parameter value P2 based on the parameter value P2. The function value J2 is calculated, and then a new parameter value P3 that gives the smallest evaluation function value among the evaluation function value J2 and Jo or Jl is determined, and then the evaluation function value corresponding to the parameter value P3 is determined. J, is calculated in the same manner as in the above case, and thereafter the parameter values of the control system are automatically corrected in the same manner,
In this way, the method for steering a ship is characterized by minimizing the resistance that the ship receives when the ship is anchored.