Electronic Engineering

1. ELECTRONIC ENGINEERING
Digital Control System

2. Digital Filters on Open-Loop System
Open-loop control systems are widely used in
numerous applications. This presentation
introduces digital filters and their importance in
the design of open-loop systems. Let's explore
together!
by Htet Wai Yan
5EcE-2R

3. CONTENTS OF THIS PRESENTATION
1. Digital Filters on Open-Loop System
2. Digital Filters: Understanding the Basics
3. Introduction to Open-Loop Systems
4. Why use Digital Filters on Open-Loop Systems?
5. Digital Filters in Digital Control Systems
6. Mathematical Expression of Digital Filters
7. Software Implementation of Digital Filters using MATLAB
8. Application of Digital Filters on Open-Loop Systems
9. Pros and Cons of Using Digital Filters
10. Conclusion

4. Digital Filters: Understanding the Basics
Digital filters are algorithms
that remove unwanted
components from signals.
What are digital filters?
1
Digital filters operate in the
digital domain, processing
signals that have been
converted from analog to
digital form.
How do they work?
2

5. Digital Filters: Understanding the Basics
They improve signal quality
and reduce the impact of
noise, thereby enhancing
system performance.
Why are they important?
3
Low-pass, high-pass, band-
pass, and band-stop filters
are some common digital
filters found in open-loop
systems.
Types of digital filters
4

6. Introduction to
Open-Loop Systems

7. What are open-
loop systems?
An open-loop system operates
without feedback, meaning that the
output is not compared to the
desired signal.

8. Components of
open-loop systems
A typical open-loop system
consists of a controller, actuator,
and plant.

9. Why are they used?
Open-loop systems are simple and fast,
and are often used for processes that are
predictable and require single control
outputs.

10. Why use Digital Filters on Open-Loop Systems?
Cost-Effective
Generally cheaper than analog
filters and have a longer
lifespan.
Reduce Noise
Reducing the effect of noise on
signals, which can improve the output
quality of open-loop systems.
Efficient
Processing
Digital filters are
computationally efficient
and can be implemented using
low-cost processors.

11. Challenges
Digital Filters in Digital Control Systems
Digital filters in digital
control systems help
achieve desired
frequency response,
harmonics reduction
and high precision
output.
Advantages
Digital filters offer a
wide range of cutoff
frequencies, linearity,
and the ability to
correct for non-
linearities in the
system.
Digital filters require
proper design and
implementation for
their optimal
performance and can
be susceptible to
quantization errors
and delays.
11

12. Challenges
Digital Filters in Digital Control Systems
Digital filters in digital
control systems help
achieve desired
frequency response,
harmonics reduction
and high precision
output.
Advantages
Digital filters offer a
wide range of cutoff
frequencies, linearity,
and the ability to
correct for non-
linearities in the
system.
Digital filters require
proper design and
implementation for
their optimal
performance and can
be susceptible to
quantization errors
and delays.
12

13. Challenges
Digital Filters in Digital Control Systems
Digital filters in digital
control systems help
achieve desired
frequency response,
harmonics reduction
and high precision
output.
Advantages
Digital filters offer a
wide range of cutoff
frequencies, linearity,
and the ability to
correct for non-
linearities in the
system.
Digital filters require
proper design and
implementation for
their optimal
performance and can
be susceptible to
quantization errors
and delays.
13

14. Types of Digital Filters
 Linear filters & Non-linear filters
 Causal filter & Non-causal filter
 Time-invariant filter & Time-variant filter
 Stable filter & Unstable filter
 Finite impulse response(FIR) filter
 Infinite impulse response (IIR) filter

15. Mathematical Expression of
Digital Filters
1
n
ion
n be
gn
2
in
m.
3

16. Mathematical
Expression of
Digital Filters
1
Transfer Function
Derive the transfer function
of a digital filter and it can be
used to analyze and design
the filter.
2
in
m.
3

17. Mathematical
Expression of
Digital Filters
1
Transfer Function
Derive the transfer function
of a digital filter and it can be
used to analyze and design
the filter. 2
Z-Transform
The role of the Z-transform is
representing discrete-time
signals and systems, and it
relates to the Fourier transform.
𝐻(𝑧) =
(𝑧 ^ 2 + 2𝑧 + 1)
(𝑧 ^ 2 + 1/4 ∗ 𝑧 − 3/8)
/
3

18. Mathematical
Expression of
Digital Filters
1
Transfer Function
Derive the transfer function
of a digital filter and it can be
used to analyze and design
the filter. 2
Z-Transform
The role of the Z-transform in
representing discrete-time
signals and systems, and it
relates to the Fourier transform.
𝐻(𝑧) =
(𝑧 ^ 2 + 2𝑧 + 1)
(𝑧 ^ 2 + 1/4 ∗ 𝑧 − 3/8)
/
3

19. Software Implementation
of Digital Filters using
MATLAB

20. How to create digital
filters in MATLAB
MATLAB provides a range of tools
for designing digital filters. We can
create filters using built-in functions
and Simulink or using the Filter
Design and Analysis app.

21. Design of a minimum-order lowpass FIR filter with a passband frequency of
0.37*pi rad/sample, a stopband frequency of 0.43*pi rad/sample , a passband
ripple of 1 dB and a stopband attenuation of 30 dB.
Fpass = 0.37;
Fstop = 0.43;
Ap = 1;
Ast = 30;
d = designfilt('lowpassfir’,
'PassbandFrequency',Fpass,...
‘StopbandFrequency',Fstop,
‘PassbandRipple',Ap,
'StopbandAttenuation',Ast);
hfvt = fvtool(d);
MATLAB Code

22. Application of Digital Filters on Open-Loop Systems
Digital filters can be used to
process and filter signals from
sensors and other inputs in
open-loop control systems.
Signal Processing Navigation and Guidance
Digital filters can improve the
accuracy and stability of
navigation and guidance systems
in open-loop control systems,
such as drones and robots.
Motion Control
Use digital filters to control
the motion of motors and
other actuators in open-loop
systems and optimize
performance.

23. Pros and Cons of Using Digital Filters
selecting the right filter type and
parameters, and testing and verifying
the filter performance.
Best Practices
computational complexity, and how
to overcome them.
Limitations
improved accuracy, stability, and
noise reduction
Advantages
01
02
03

24. Conclusion
Digital filters are versatile tools for improving the output quality
and performance of open-loop systems. They offer efficient
processing, cost-effective design, and can be implemented using
software tools like MATLAB. However, care must be taken
during filter design and implementation to ensure optimal
performance and avoid non-linearities.

25. References
• Jervis, B. W. (2019). The Digital Filter Handbook.
Springer.
• Oppenheim, A. V., & Schafer, R. W. (2010). Discrete-
time signal processing (3rd ed.). Pearson.
• en.m.wikipedia.org/wiki/Digital_filter
• https://www.mathworks.com/help/signal/ug/practical-
introduction-to-digital-filter-design.html

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