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Algorithms to control the moving ship during harbour entry
- Source :
- Applied Mathematical Modelling. 33(5):2474-2490
- Publication Year :
- 2009
- Publisher :
- Elsevier BV, 2009.
-
Abstract
- Automation is being accepted for control systems onboard ships in view of the shortage of skilled manpower in marine sector. Control theory has long been applied to maneuvering problems and at present this trend is continuing at an increased rate. This is for speed control, course control and path keeping. Heading control and course keeping are very important for surface ships while they enter shallow water regions. A typical situation is the entry of a large commercial ship into the harbour basin. The ship faces a sudden change of forces and moments around it due to the change in the hydrodynamics. The Master of the ship regulates the speed while entering the basin. Forces and moments, due to the hydrodynamic flow around the moving hull, are balanced by the rudder behind it. The feed back from the heading angle is taken and the gain in the control system prompts the steering gear to turn the rudder. The conventional control algorithm based on PID is attempted in the first part of the paper and case studies are shown for a Mariner class ship whose hydrodynamic derivatives are known. Displacement, velocities and accelerations are determined for short duration from the simulation of a voyage in calm water. The proposed system can be implemented into autopilot systems. The codes developed in MATLAB can accommodate wind and wave forces as well. The simulation is of a general type and can be used for other vessels with a change in the constants of P (Proportional), I (Integral) and D (Derivative) which can be arrived at by trial and error. The design of the control system depends on the choice of the three control constants Kp, Ki and Kd. These will change as per sea state and extra loads. The control of motions in shallow water and deep water cases are discussed in the paper. In the next part of the paper, fuzzy logic control is discussed. Fuzzy logic is applied to control the heading and bring the path of the vessel to the desired level. The models discussed are versatile because of the provision for add-on facility for wind, wave or any other environmental loads. The rudder turning rate is taken as that for commercial ships. In the near future, a combined control system for ship maneuvering can be possible by considering both the PID and Fuzzy based algorithm. The two algorithms with suitable modifications are useful for non-linear cases. It is also tried to compare the two methods and an attempt is made to find out which is better and acceptable. � 2008 Elsevier Inc. All rights reserved.
- Subjects :
- Fuzzy sets
Engineering
Shallow waters
PID controller
Environmental loads
Autopilot systems
Hydrodynamic flows
Time varying control systems
Control system analysis
law.invention
Control theory
law
Hull
Linear maneuver
Trial and errors
Short durations
Surface Ships
Applied Mathematics
Rudder
Wave forces
Harbour basins
Modeling and Simulation
Autopilot
Steering gears
Steering
Algorithm
Derivatives
Deep waters
Paper
MATLAB
Heading (navigation)
Course keepings
Three term control systems
Ship steering equipment
Fuzzy control
Course (navigation)
Skilled manpowers
Rudders
Commercial ships
Fuzzy logic controls
Fluid dynamics
Two term control systems
Modelling and Simulation
PID control
Ship maneuverings
Ships
Conventional controls
Combined controls
Marine sectors
Control systems
business.industry
Fuzzy systems
Heading controls
Sea states
Fuzzy logic
Ocean currents
Heading angles
Control system
Hydrodynamic derivatives
Hydrodynamics
Turning rates
Case studies
Proportional control systems
business
Sudden changes
Subjects
Details
- ISSN :
- 0307904X
- Volume :
- 33
- Issue :
- 5
- Database :
- OpenAIRE
- Journal :
- Applied Mathematical Modelling
- Accession number :
- edsair.doi.dedup.....5c344ff87244b547f14edb9e283cfe43
- Full Text :
- https://doi.org/10.1016/j.apm.2008.07.012