Lab, v. Scheepsbouwkuncie
Technische Hogesckool
Deft
Paper n. 5
"MASTERPILOT SYSTEM MANOEUVRE CONTROL"
E. Brizzolara - SCHOTTEL ITALIANA
NAV '88 - WEMT '88 SYMPOSIUM
Trieste, Italy12 - 13 - 14 October 1988
Abstract:
The inst&llation of many azimuthal thruster on the same vessel permit to reach unexpected
manoeuvra-bility. To simplify the shipmasters control of
many units simultaneously, Schottel developed its own computerized control, called MASTERPILOT. This device is able to control each unit in thrust
and direction in order to obtain the requested ship movement in parallel motion with or without superimposed turning angle.
The hardware is a Schottel standard product, mean-while the software is developed for each applica-tion based on Schottel large experience.
The MASTERPILOT units are installed in a large number of different type of vessels, like ferries, tractor tugs, special ships, firefighting boats, defence vehicles, etc.. arid can control any number of thruster.
The number of crafts and ships that are equipped with azimutal thruster
is growing continuously. The azimuthal thrusters or S.R.P. (Schottel Rudder Propellers) are rarely installed as a single unit.
The biggest part of applications is related to two or more units on the same ship and commonly the units are be of different powers or, better, of different thrust.
In these applications the rudder proppellers can be controlled with different systems:
- a - one by one with single and separate follow-up control; - b - with automatic computer control for D.P. operations; - c - with one hand lever computerized control.
The system - a - still in use for ships equipped with 2 or 3 SRP is shown in figure 1 and consist of one small pre-selecting wheel for each azimutal thruster.
The consolle shown in figure 1 is the pilot-house consolle of a tanker equipped with 2 SRP at the stern.
For special applications like D.P. in the offshore vessels the number
of SRP installed on board can be 4 or more reaching also 8 or 10 units.
All the SRP are controlled in thrust and in azimuth automatically by the D.P. computer (system - b -). But many applications require a prompt, direct shipmaster control and, of course, it is not simple for him to steer all the power units simultaneously, during quick and
precise manoeuvres.
This is the reason why Schottel developed the MASTERPILOT System for their rudder propellers and for their azimuthal jets.
The function, advantages and experiences with this usefull steering device can be described as follows.
A ship with two or more Rudderpropellers or other manoeuvring aids can execute almost all conceivable manoeuvres and motions. Therefore, not only it can sail straight ahead, astern or in random curves, but it can
also, as shown on the figures 2 and 3, move transversally in random
directions in addition to superimposed rotations and also turning on
the spot.
In developing the input device and the software, Schottel have taken
other handling and application scope approaches in comparison with competitors.
The system configuration of the tractor tug was chosen as the first program.
And this was for a good reason, because the customer had seen repeated demonstration of perfect tug manoeuvring in the port of Hamburg.
The fact that a lot of experience and practise is required for this purpose, however, was mostly overlooked. Translating this experience
into a program and developing a simple input device for the purpose was the first objective.
In the meanwhile this software has been supplemented by many others and so almost any propulsion configuration is programmed. (Figure 4)
Now a few basic details of the Masterpilot:
The Schottel Masterpilot control is a microcomputer control for ships (Figure 5).
A clearly arranged input unit permits the shipmaster to execute all
conceivable manoeuvres extremely rapidly without having to waste thoughts of engine speeds, propeller pitches or directions of thrust. The shipmaster can thus concentrate himself entirely on the ship's work and mission, while the microcomputer relieves him of the task of set-ting control elements.
The MASTERPILOT control permits ship's motions with a degree of
precision wich would demand a considerable amount of experience of the
part of the shipmaster if the thrusters were to be controlled manually.
The input unit of the Masterpilot control is matched in the best
possible way to the ship's possibilities of movement. In order to
undestand it, it is first of all necessary to remember, that the motion
of a ship can basically be split up into two parts: a longitudinal motion and a rotation.
It is thus logical that the input unit is designed so that the
direc-tion and the intensity of both modirec-tions are entered separately and can
be superimposed on each other (Figures 6 and 7).
The central lever specifies the direction and intensity of the required longitudinal motion while the outer handwheel specifies those of the
required rotation.
The complete task of evaluation and control is performed by the micro-processor (Figure 8). With the aid of its program the computer controls the thrust angle, clutches and the speed of all thrusters (or pitch of
CCP)
The program integrates optimized Rudderpropeller settings and
experience with the respective system configuration, thus dispensing with problems in direction of rotation inputs for direction reversals
or for tranversing with superimposed rotations. Even if a few system components should fail, the simple input setting will not change and, with the aid of an emergency program, the computer will determine and realize the ship's motions which are still possible.
Manual intervention in the steering program is also possible.
For instance, a system can be deactivated to save fuel, or it is
possible to switch between high speed (sensitive steering) and manoeuvring speed.
Just like the COPILOT system the Masterpilot input lever can also be equipped with a slaving control for simple switchover of the control position during operation.
For an automatic heading an Autopilot can be connected to the
Masterpilot system.
In this case the Autopilot replaces the handwheel of the Masterpilot input unit.
Software errors such as program interrupts or hardware faults in the computer system results an immediate switching to an emergency system. All occuring faults and errors are additionally signalled visually and acoustically.
01 01
the Copilot corisolle in a tanker equipped with 2 SRP at the stern
UNBEGRENZTE
MANVRIER-MGLICHKEITEN
DURCH
urirestri cted manoeuvrabi 1 ity
through a Schottel tractor tug
UNBEGRENZTE MANtVRI ER-MOGLICHKEITEN
DURCH
unrestri cted manoeuvrabi ii ty
through a Schottel stern tug
Figure 3
SUOfl6!.JUO
uo!.SlfldO.Ad aqssod
111
MICRO COMPUTER
T
J
the principle of a f1asterpilot system for a ship with two Rudder-propellers in the stern and two lateral thrusters in the bow
Figure 5
5.9
REMOTE REMOTE REMOTE REMOTE
CONTROL CONTROL CONTROL CONTROL
the input device of the Schottel Masterpilot System (900 transverse and superimposing rotation)
Figure 7
