Bridge Control System By Oladokun Sulaiman

BRIDGE CONTROL SYSTEM BY OLADOKUN SULAIMAN Aim To make report of ship complete electro-hydraulic system and associated control Objectives

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To discuss operation, principle components, and safety considerations related to hydraulic systems. To discuss operation, principle components, and safety considerations control of steering autopilot control feedback system.

Abstract Control system and as applied to upgrade of existing system has always been part and of human civilization. This paper will discuss the hydraulics and automatics part steering control system.

Introduction A ship control system is complex and steering and its associated system is complex. Earlier ship control system are most operated using flow rate with float, whereas recent system are operated with control feedback and damper arrangement for start and stop. This work will discuss in two parts- the complete steering system of the ship – the hydraulic operated part and the feedback control part.

Ship steering system Background: Ship steering system is mechanism that transmits power from the steering engine to the rudder. Hydraulic system is made of Steering gear rudder, stern planes, and tiller Principle of operations •

Hydraulic system operate on Pascal law, that states that – “Pressure in a fluid acts equally in all directions” and using the (Shapelessness, Incompressibility , Transmission of force) Properties of liquid

PRESSURE = FORCE/AREA

Find Pressure Find F2

F2 =

200 lbf A 1 = 20 in2

F1 = 20 lbf A 1 = 2 in2

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Pressure = 10 psi

Reservoir - Storage Tank Pressure source - Hydraulic pump (A-end) Pressure user - (B-end) – Hydraulic motor - rotary motion – Hydraulic cylinder - linear motion Piping systems – valves, filters, heat exchangers Accumulator - stores pressurized oil

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Hydraulic fluid (normally oil)

Description and specification of components

A simple The steering system of the ship has an arrangement where the pumps are connected by piping to the cylinder, two pipes are connected to by multiported valves and other pipe s from other pumps are connected for bypassing and the ram is also connected to the tiller.

Method of operations

Different method is use to connect the ram to he tiller, however the same principle apply. An electro hydraulic steering system has system has the following components that work in a similar way and principle as described.

Electro-hydraulic Steering Gear •

Ram unit – Tiller

– Cylinder – Hand pump – Follow-up Shaft Electro-hydraulic Steering Gear •

Power unit – Electric motor – Waterbury pump (A end) – Transfer valves – Remote steering unit – Trick wheel

Method of control •

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Normal control from ship's bridge – Utilizes remote electrical signal to control tilt-box position of hydraulic pump Alternate control from after steering – "Trick wheel” manually operated to control tilt-box angle Emergency control – Hand pump - Manually pressurizes hydraulic fluid to take local control of rudder

Conclusion: The steering gear use oil as fluid and advantage non-corrosive and superb lubrication give steering gear good performance. Moreso it is convenient, flexible, variable speed control, safety and reliability method of power transmission over long distances,

however backdrop lies on positive confinement, leaks in high pressure systems pose a safety hazard and adequate oil filtration must be maintained

Ships autopilot system Background Control of ship movement started with use of celestial observation - earlier ship fearer stared with us of almanac, map, and sextant, to invention of electrically driven gyroscope and magnetic compass until 1911 when gyrocompass- autopilot system which uses a control feedback was invented.

Principle of operations The auto plot system work on control three term control law –proportional-integralderivative (PID). Simple autopilot system use a single input single out put control system where the heading of the ship is measure ed by gyrocompass. With introduction of control feedback system the signal is fed back to the computer PID (auto- pilot), which follow commands of the software.

Pilot input

Autopilot

Ruder

Compass

Heading angle

Feedback system issued in auto plot system by maintaining the following principle ƒ ƒ ƒ

Position data Rate of data Accumulation of error data

Description and specification of components

The autopilot system is complex system divided into following components The input –Coonected from different sensor to the controller o Gyroscop compass o GPS o Wind sensor o Human input Outputs- To move vessel around to desired position o Main propulsion o Tunnel thrusters o Azimuth Controller- It is recommended for efficient control system that autopilot system to have o Good output feedback o Good wave notch filtering o And good integral action for compensation of wave drifts.

Methods of control Course changing – Here the input come from the plot as a step command, the rudder is then rotated in the direction of the desired course. The amount of heading change is determined by the amplitude of the step command and heading and position of the pilot are determined by the judgement of the helmsman. Input comman

State Desired response

Controller

Vessel

Controller

Figure : Course changing TRACKEEPING: Here the control of the heading and the position is done by the autopilot. It takes position information and calculates the heading and correction real-time to make the vessel follow the prêt ermined course.

Input comman

state Desired response

Controller

Vessel

Controller

Vessel position

Figure: Track keeping Conclusion A good auto pilot can improve vessel profit margin by reducing number of ship personnel and fuel consumption. the drawback remain with leak associated the hydraulic system.