Electronic Systems and Computer Technology - Decreasing Fuel Consumption and Exhaust Gas Emissions in Transportation - page 94

injection
pump

actuator

engine generator

impulse receiver

3

1
2

analogue
electronic module

4
5

desired value

1. divided monitoring
feedback
2. output transfer

3. P control
4. I control
5. D control

Fig. 6.1 Analogue control and regulation devices in a ship's engine

signal between 0 and 1.1 V. Digital systems transform continuous analog signals
to discrete digital signals which represent two states, zero and a higher level one.
They are more precise than analog signals and can be processed by computer
controlled software. Digital circuits are usually more expensive and need a higher
supply power than analog systems [ 3 ].
Digital parameters are the number of revolutions or individual positions in the
engine which can be measured with impulse receivers. Digital-Analog Converters
(DAC) convert digital signals to analog signals to drive electric motors or regulate
actuators in vehicles, airplanes, and ships [ 4 ].
The hardware consists of electronic components on a printed circuit board
equipped with analog elements, such as resistors, condensers, switchers, connec-
tors, plugs, etc., and digital elements, such as integrated circuits and micro con-
trollers (lC) [ 5 ].
The software is stored in the micro controller or other chips on the electronic
circuit, typically in an Electrically Erasable Programmable Read-Only Memory
(EEPROM) or flash memory. A micro controller is a small computer on a single
integrated circuit containing a processor core, a memory and a programmable
input or output peripherals. Programmable control units do not have fixed char-
acteristics and can be reprogrammed by the user or the operator for several
measures which are not essential for the basic functioning of the system [ 6 ].
In ships, digital systems may communicate text from Computer-Aided Dispatch
(CAD). Digital processing, combined with the relatively narrow receiver bandwidths,
provides a high quality of signal transmission with resistance to noise and fading [ 7 ].
Electronic systems secure more and more complex in all types of transportation
means, i.e., in road vehicles, airplanes, and ships (see Fig. 6.2 ).