Adaptive fuzzy ship autopilot for track-keeping. 指導教授 : 曾 慶 耀 學 號 :10267036 學 生 : 潘 維 剛. Outline. 1. Introduction 2. System description 3. Adaptive fuzzy track-keeping autopilot 4. Simulation results 5. Conclusion. 1. Introduction.
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指導教授:曾 慶 耀學 號:10267036學 生:潘 維 剛
2. System description
3. Adaptive fuzzy track-keeping autopilot
4. Simulation results
capability of adjustment of its scaling factors.
2.1. Ship dynamics
The position and orientation of the ship are described relative to the inertial reference frame OE-xEyEzE (Earth-fixed reference frame).
The general ship equations of motion can be expressed in compact form as
is a generalized vector of external forces and moments.
Due to that 6DOF model is simplified and reduced to 3DOF model (Fig. 3).
For this ship the nonlinear mathematical model which relates the yaw (Ψ) with the rudder angle (δ) is described by the following equations:
electrohydraulic steering subsystems: telemotor position servo and rudder servo actuator (Fig. 4).
The desired way point is Hence, the desired heading angle can be obtained from the expression:
the desired way point can be calculated from
The output variable y of type autopilot obtained constant values (NB→-3,NM → -2, . . . ,PM → 2, PB → 3).
Shapes of membership functions of input variables are shown in Fig. 8. Labels for the membership functions are given in Table 1.
These rules contain the input/output relationships that define the control strategy. The fuzzy autopilot uses 49 rules, corresponding to 7*7 different combinations of the two input fuzzy sets. (Table 2).
Ψ and one output: gain k: In this section, a fuzzy tuning method for the gain of FLC variables is presented.
and output variable are shown in Figs. 10–12.
IF d is NE and Ψ is PS then ki is PS
IF d is NE and Ψ is PM then ki is PM
IF d is NE and Ψ is PB then ki is PB
IF d is ZE and Ψ is PS then ki is PB
IF d is ZE and Ψ is PM then ki is PM
IF d is ZE and Ψ is PB then ki is PS
IF d is PE and Ψ is PS then ki is PS
IF d is PE and Ψ is PM then ki is PB
IF d is PE and Ψ is PB then ki is PM
This set of rules is the same for the ke ; kr and ky:
Fig. 14 shows the time responses of heading , commanded rudder angle (δc) and rudder angle (δ) during a course-changing maneuver . The heading time response is without overshoot and oscillation during transient response. The response of the rudder is rather smooth.
and standard fuzzy autopilots is presented.
The results of the comparative performance test showed that adaptive fuzzy autopilot has shown much better performance in comparison with the standard fuzzy type autopilot.