Professor Charlton S. Inao Control System Engineering-PE -3032

Defence University College of Engineering

Bishoftu, Ethiopia

Week 17

Digital Control System

Instructional Objectives To explain and understand the following

concept:

Digital Control System Sampling Process Intro to Z transform

Introduction to Digital

Control System

Digital Control System

Number System Decimal Binary BCD Octal Hexadecimal0 0000 0000 0000 0 01 0001 0000 0001 1 12 0010 0000 0010 2 23 0011 0000 0011 3 34 0100 0000 0100 4 45 0101 0000 0101 5 56 0110 0000 0110 6 67 0111 0000 0111 7 78 1000 0000 1000 10 89 1001 0000 1001 11 910 1010 0001 0000 12 A11 1011 0001 0001 13 B12 1100 0001 0010 14 C13 1101 0001 0011 15 D14 1110 0001 0100 16 E15 1111 0001 0101 17 F

Digital Signal

A digital signal is a physical signal that is a representation of a sequence of discrete values (a quantified discrete-time signal), for example of arbitrary bit stream, or of a digitized (sampled and analog-to-digital converted) analog signal. The term digital signal can refer to a continuous-time waveform signal used in any form of digital communication.

A pulse train signal that switches between a discrete number of voltage levels or levels of light intensity, also known as a a line coded signal, for example a signal found in digital electronics or in serial communications using digital baseband transmissionin, or a pulse code modulation (PCM) representation of a digitized analog signal.

A signal that is generated by means of a digital modulation method (digital passband transmission), produced by a modem, is in the first case considered as a digital signal, and in the second case as converted to an analog signal.

Analog/Continuous Signals

Example of analog and digital

Exercise

Advantages of Digital Signals• The main advantage of digital signals over analog

signals is that the precise signal level of the digital signal is not vital.

• This means that digital signals are fairly immune to the imperfections of real electronic systems which tend to spoil analog signals.

• Reduced cost• Flexibility in response to design changes• Noise immunity• Easy to control and manipulate

Digital Control System

Data Acquisition/Sampling

• Data acquisition is the process of sampling signals that measure real world physical conditions and converting the resulting samples into digital numeric values that can be manipulated by a computer.

• Data acquisition systems (abbreviated with the acronym DAS or DAQ) typically convert analog waveforms into digital values for processing.

The components of data acquisition systems include:

• Sensors that convert physical parameters to electrical signals.

• Signal conditioning circuitry to convert sensor signals into a form that can be converted to digital values.

• Analog-to-digital converters, which convert conditioned sensor signals to digital values.

Analog to Digital Conversion

Analog to digital

Analog to digital- digital to analog

Sampling Process

Sampling Process Theory

The Z Transform

Example Long Division Method

Solution

Sample problem

Solution

Sample Problem

Solution

Matlab samples for continuous and discrete

The EndThank You Very Much