Ch2 mathematical modeling of control system Elaf A.Saeed
Chapter 2 Mathematical modeling of control system From the book (Ogata Modern Control Engineering 5th).
2-1 introduction.
2-2 transfer function and impulse response function.
2-3 automatic control systems.
Ch2 mathematical modeling of control system Elaf A.Saeed
Chapter 2 Mathematical modeling of control system From the book (Ogata Modern Control Engineering 5th).
2-1 introduction.
2-2 transfer function and impulse response function.
2-3 automatic control systems.
State-Space Analysis of Control System: Vector matrix representation of state equation, State transition matrix, Relationship between state equations and high-order differential equations, Relationship between state equations and transfer functions, Block diagram representation of state equations, Decomposition Transfer Function, Kalman’s Test for controllability and observability
Level Control of Tank System Using PID Controller-A ReviewIJSRD
This paper discusses the review of level control of tank system using PID controller. PID controller use for one or more tank system. PID has fast response. Paper present different methods of level control. Eliminate the steady state error. It is most common way of solving problems of practical control systems.
this is presentation about time response analysis in control engineering. this is presentation on its types and many more like time responses with best example
Control of non linear system using backsteppingeSAT Journals
Abstract The defining attribute of a servomechanism is that the controlled output of a mechanism is automatically compared with the controlling input. The difference between the settings or positions of the output and the input is called the error signal, which acts to bring the output to its desired value.The paper work shows the application of backstepping technique to stabilize a nonlinear dynamical system. Any nonlinear dynamical system can be stabilized only by means of Lyapunov function approach. In this approach backstepping technique is invariably adopted. In case of normal backstepping technique stabilizing function is designed at every step of dynamics starting from the output towards input. The Backstepping approach provides a recursive method for stabilizing the origin of a system in strict-feedback form. The controller contains the terms of system state variables, reference input & its derivatives, and error. The basic aim of the controller is to settle down error and its derivatives to zero. The controller is designed through Lyapunov based function so as to render strong closed loop stability.In the theory of control systems, Lyapunov functions are scalar functions that may be used to prove the stability of equilibrium of a control system. Keywords: Lyapunov function, backstepping, nonlinear system, stability, derivative
Introduction, Translational Motion, Rotational Motion, Analogous Elements, Electrical Elements, Analogous System, Force - Voltage Analogy, Torque Voltage Analogy, Force - Current Analogy, and Steps to solve problems on analogous systems.
State variable analysis (observability & controllability)SatheeshCS2
Mr. C.S.Satheesh, M.E.,
State Variable Analysis
Observability
Controllability
Concept of state variables
State models for linear and time invariant Systems
Solution of state and output equation in controllable canonical form
Concepts of controllability and observability
Effect of state feedback.
Artificial Intelligence lecture notes. AI summarized notes on uncertainty and handling it through fuzzy logic, tipping problem scenarios are seen in it, for reading and may be for self-learning, I think.
Mathematical Modelling of Control SystemsDivyanshu Rai
Different types of mathematical modeling in control systems [which include Mathematical Modeling of Mechanical and Electrical System (which further includes, Force-Voltage and Force-Current Analogies)]
Cascade control of superheated steam temperature with neuro PID controllerISA Interchange
In this paper, an improved cascade control methodology for superheated processes is developed, in which the primary PID controller is implemented by neural networks trained by minimizing error entropy criterion. The entropy of the tracking error can be estimated recursively by utilizing receding horizon window technique. The measurable disturbances in superheated processes are input to the neuro-PID controller besides the sequences of tracking error in outer loop control system, hence, feedback control is combined with feedforward control in the proposed neuro-PID controller. The convergent condition of the neural networks is analyzed. The implementation procedures of the proposed cascade control approach are summarized. Compared with the neuro-PID controller using minimizing squared error criterion, the proposed neuro-PID controller using minimizing error entropy criterion may decrease fluctuations of the superheated steam temperature. A simulation example shows the advantages of the proposed method.
This is an Introductory material for those who want to understand the basic difference between linear and nonlinear analysis in the context of civil and structural engineering.
Control of Uncertain Hybrid Nonlinear Systems Using Particle FiltersLeo Asselborn
This paper proposes an optimization-based algorithm for the control of uncertain hybrid nonlinear systems. The considered system class combines the nondeterministic evolution of a discrete-time Markov process with the deterministic switching of continuous dynamics which itself contains uncertain elements. A weighted particle filter approach is used to approximate the uncertain evolution of the system by a set of deterministic runs. The desired control performance for a finite time horizon is encoded by a suitable cost function and a chance-constraint, which restricts the maximum probability for entering unsafe state sets. The optimization considers input and state constraints in addition. It is demonstrated that the resulting optimization problem can be solved by techniques of conventional mixed-integer nonlinear programming (MINLP). As an illustrative example, a path planning scenario of a ground vehicle with switching nonlinear dynamics is presented.
State-Space Analysis of Control System: Vector matrix representation of state equation, State transition matrix, Relationship between state equations and high-order differential equations, Relationship between state equations and transfer functions, Block diagram representation of state equations, Decomposition Transfer Function, Kalman’s Test for controllability and observability
Level Control of Tank System Using PID Controller-A ReviewIJSRD
This paper discusses the review of level control of tank system using PID controller. PID controller use for one or more tank system. PID has fast response. Paper present different methods of level control. Eliminate the steady state error. It is most common way of solving problems of practical control systems.
this is presentation about time response analysis in control engineering. this is presentation on its types and many more like time responses with best example
Control of non linear system using backsteppingeSAT Journals
Abstract The defining attribute of a servomechanism is that the controlled output of a mechanism is automatically compared with the controlling input. The difference between the settings or positions of the output and the input is called the error signal, which acts to bring the output to its desired value.The paper work shows the application of backstepping technique to stabilize a nonlinear dynamical system. Any nonlinear dynamical system can be stabilized only by means of Lyapunov function approach. In this approach backstepping technique is invariably adopted. In case of normal backstepping technique stabilizing function is designed at every step of dynamics starting from the output towards input. The Backstepping approach provides a recursive method for stabilizing the origin of a system in strict-feedback form. The controller contains the terms of system state variables, reference input & its derivatives, and error. The basic aim of the controller is to settle down error and its derivatives to zero. The controller is designed through Lyapunov based function so as to render strong closed loop stability.In the theory of control systems, Lyapunov functions are scalar functions that may be used to prove the stability of equilibrium of a control system. Keywords: Lyapunov function, backstepping, nonlinear system, stability, derivative
Introduction, Translational Motion, Rotational Motion, Analogous Elements, Electrical Elements, Analogous System, Force - Voltage Analogy, Torque Voltage Analogy, Force - Current Analogy, and Steps to solve problems on analogous systems.
State variable analysis (observability & controllability)SatheeshCS2
Mr. C.S.Satheesh, M.E.,
State Variable Analysis
Observability
Controllability
Concept of state variables
State models for linear and time invariant Systems
Solution of state and output equation in controllable canonical form
Concepts of controllability and observability
Effect of state feedback.
Artificial Intelligence lecture notes. AI summarized notes on uncertainty and handling it through fuzzy logic, tipping problem scenarios are seen in it, for reading and may be for self-learning, I think.
Mathematical Modelling of Control SystemsDivyanshu Rai
Different types of mathematical modeling in control systems [which include Mathematical Modeling of Mechanical and Electrical System (which further includes, Force-Voltage and Force-Current Analogies)]
Cascade control of superheated steam temperature with neuro PID controllerISA Interchange
In this paper, an improved cascade control methodology for superheated processes is developed, in which the primary PID controller is implemented by neural networks trained by minimizing error entropy criterion. The entropy of the tracking error can be estimated recursively by utilizing receding horizon window technique. The measurable disturbances in superheated processes are input to the neuro-PID controller besides the sequences of tracking error in outer loop control system, hence, feedback control is combined with feedforward control in the proposed neuro-PID controller. The convergent condition of the neural networks is analyzed. The implementation procedures of the proposed cascade control approach are summarized. Compared with the neuro-PID controller using minimizing squared error criterion, the proposed neuro-PID controller using minimizing error entropy criterion may decrease fluctuations of the superheated steam temperature. A simulation example shows the advantages of the proposed method.
This is an Introductory material for those who want to understand the basic difference between linear and nonlinear analysis in the context of civil and structural engineering.
Control of Uncertain Hybrid Nonlinear Systems Using Particle FiltersLeo Asselborn
This paper proposes an optimization-based algorithm for the control of uncertain hybrid nonlinear systems. The considered system class combines the nondeterministic evolution of a discrete-time Markov process with the deterministic switching of continuous dynamics which itself contains uncertain elements. A weighted particle filter approach is used to approximate the uncertain evolution of the system by a set of deterministic runs. The desired control performance for a finite time horizon is encoded by a suitable cost function and a chance-constraint, which restricts the maximum probability for entering unsafe state sets. The optimization considers input and state constraints in addition. It is demonstrated that the resulting optimization problem can be solved by techniques of conventional mixed-integer nonlinear programming (MINLP). As an illustrative example, a path planning scenario of a ground vehicle with switching nonlinear dynamics is presented.
Nonlinear Structural Dynamics: The Fundamentals TutorialVanderbiltLASIR
This presentation from Dr. Douglas Adams, Chairman of Civil & Environmental Engineering at Vanderbilt University, and Director of the Laboratory for Systems Integrity and Reliability (LASIR), introduces the fundamental concepts of nonlinear structure dynamics.
We present an ab-initio real-time based computational approach to nonlinear optical properties in Condensed Matter systems. The equation of mot ions, and in particular the coupling of the electrons with the external electric field, are derived from the Berry phase formulation of the dynamical polarization. The zero-field Hamiltonian includes crystal local field effects, the renormalization of the independent particle energy levels by correlation and excitonic effects within the screened Hartree- Fock self-energy operator. The approach is validated by calculating the second-harmonic generation of SiC and AlAs bulk semiconductors : an excellent agreement is obtained with existing ab-initio calculations from response theory in frequency domain . We finally show applications to the second-harmonic generation of CdTe the third-harmonic generation of Si.
Reference :
Real-time approach to the optical properties of solids and nanostructures : Time-dependent Bethe-alpeter equation Phys. Rev. B 84, 245110 (2011)
Nonlinear optics from ab-initio by means of the dynamical Berry-phase
C. Attaccalite and M. Gruning Phys. Rev. B 88 (23), 235113 (2013)
Computational Motor Control: State Space Models for Motor Adaptation (JAIST s...hirokazutanaka
This is lecure 3 note for JAIST summer school on computational motor control (Hirokazu Tanaka & Hiroyuki Kambara). Lecture video: https://www.youtube.com/watch?v=dtpgJLRt90M
A simple, widely used control method. This presentation will provide an introduction to PID controllers, including demonstrations, and practise tuning a controller for a simple system.
From the Un-Distinguished Lecture Series (http://ws.cs.ubc.ca/~udls/). The talk was given Mar. 30, 2007.
Secure Communication and Implementation for a Chaotic Autonomous SystemNooria Sukmaningtyas
In this paper, a three-dimensional chaotic autonomous system is presented. The stability of the
equilibrium and the conditions of the Hopf bifurcation are studied by means of nonlinear dynamics theory.
Then, the circuit of chaotic system is structured out in Multisim platform by the unit circuit. The chaotic
system is applied to secure communications by linear feedback synchronization control. All simulations
results performed on three-dimensional chaotic autonomous system are verified the applicable of secure
communication.
Biomedical Control systems-Block Diagram Reduction Techniques.pptxAmnaMuneer9
This is all about block diagram reduction in the course Biomedical Control Systems. Its about reducing systems into transfer functions, and figuring out how to convert analog resistors, capacitors and inductors into the frequency domain by Laplace transformation.
I am Martina J. I am a Signals and Systems Assignment Expert at matlabassignmentexperts.com. I hold a Master's in Matlab, from the University of Maryland. I have been helping students with their assignments for the past 9 years. I solve assignments related to Signals and Systems.
Visit matlabassignmentexperts.com or email info@matlabassignmentexperts.com.
You can also call on +1 678 648 4277 for any assistance with Signals and Systems assignments.
Gauss jordan and Guass elimination methodMeet Nayak
This ppt is based on engineering maths.
the topis is Gauss jordan and gauss elimination method.
This ppt having one example of both method and having algorithm.
Analysis and Design of Control System using Root LocusSiyum Tsega Balcha
Root locus analysis is a powerful tool in control systems engineering used to analyze the behavior of a system's closed-loop poles as a function of a parameter, typically a controller gain. It provides engineers with valuable insights into how changing system parameters affect stability and performance, helping them design robust and stable control systems. Let's explore the key concepts, techniques, and practical implications of root locus analysis. At its core, root locus analysis focuses on the movement of the closed-loop poles in the complex plane as a control parameter varies. These poles represent the characteristic equation's roots, which determine the system's stability and transient response. By examining the pole locations as the parameter changes, engineers can gain a deeper understanding of the system's behavior and make informed design decisions.
Linear regression [Theory and Application (In physics point of view) using py...ANIRBANMAJUMDAR18
Machine-learning models are behind many recent technological advances, including high-accuracy translations of the text and self-driving cars. They are also increasingly used by researchers to help in solving physics problems, like Finding new phases of matter, Detecting interesting outliers
in data from high-energy physics experiments, Founding astronomical objects are known as gravitational lenses in maps of the night sky etc. The rudimentary algorithm that every Machine Learning enthusiast starts with is a linear regression algorithm. In statistics, linear regression is a linear approach to modelling the relationship between a scalar response (or dependent variable) and one or more explanatory variables (or independent
variables). Linear regression analysis (least squares) is used in a physics lab to prepare the computer-aided report and to fit data. In this article, the application is made to experiment: 'DETERMINATION OF DIELECTRIC CONSTANT OF NON-CONDUCTING LIQUIDS'. The entire computation is made through Python 3.6 programming language in this article.
Fundametals of HVAC Refrigeration and AirconditioningCharlton Inao
This course is designed to tackle the fundamentals of Heating, Ventilating, Air Conditioning, and Refrigeration as they relate to human comfort in residential and industrial design applications. The main focus of the course will be to examine the fundamental criteria involved in sizing and design of HVAC systems as well as to investigate the equipment used to satisfy the design criteria. The culmination part of the course is the design of air conditioning and ventilation of a commercial or residential building as a final project or case study.
Team formation
The course is designed to explore the entrepreneurial mindset and culture, utilizing a technology or engineering background. This fits into goals of starting a company or being involved in an entrepreneurial or R&D effort in companies of all sizes and industries. The course is also applicable in training future scientist and engineers to participate in in business ventures and Research and Development (R&D) activities.
Air conditioning systems
2. Properties of moist air
3. Moist air processes
4. Space air conditioning
5. Indoor air quality--comfort and health
6. Heat transfer from human body
7. Heat transfer in building envelopes
8. Infiltration heat load and weatherizing
9. Computation of the heating load
10. Heat gain by solar radiation
11. Computation of the cooling load
12. Energy requirements for HVAC systems; building energy audit
13. Fans--performance, selection, and installation
14. Air flow in ducts and fittings
15. Design of duct systems
16. Codes & standards for building energy systems
17. Annual energy consumption
Air conditioning systems
2. Properties of moist air
3. Moist air processes
4. Space air conditioning
5. Indoor air quality--comfort and health
6. Heat transfer from human body
7. Heat transfer in building envelopes
8. Infiltration heat load and weatherizing
9. Computation of the heating load
10. Heat gain by solar radiation
11. Computation of the cooling load
12. Energy requirements for HVAC systems; building energy audit
13. Fans--performance, selection, and installation
14. Air flow in ducts and fittings
15. Design of duct systems
16. Codes & standards for building energy systems
17. Annual energy consumption
Air conditioning systems
2. Properties of moist air
3. Moist air processes
4. Space air conditioning
5. Indoor air quality--comfort and health
6. Heat transfer from human body
7. Heat transfer in building envelopes
8. Infiltration heat load and weatherizing
9. Computation of the heating load
10. Heat gain by solar radiation
11. Computation of the cooling load
12. Energy requirements for HVAC systems; building energy audit
13. Fans--performance, selection, and installation
14. Air flow in ducts and fittings
15. Design of duct systems
16. Codes & standards for building energy systems
17. Annual energy consumption
Air conditioning systems
2. Properties of moist air
3. Moist air processes
4. Space air conditioning
5. Indoor air quality--comfort and health
6. Heat transfer from human body
7. Heat transfer in building envelopes
8. Infiltration heat load and weatherizing
9. Computation of the heating load
10. Heat gain by solar radiation
11. Computation of the cooling load
12. Energy requirements for HVAC systems; building energy audit
13. Fans--performance, selection, and installation
14. Air flow in ducts and fittings
15. Design of duct systems
16. Codes & standards for building energy systems
17. Annual energy consumption
The course is designed to explore the entrepreneurial mindset and culture, utilizing a technology or engineering background. This fits into goals of starting a company or being involved in an entrepreneurial or R&D effort in companies of all sizes and industries. The course is also applicable in training future scientist and engineers to participate in in business ventures and Research and Development (R&D) activities.
Nme 515 air conditioning and ventilation systems for submissionCharlton Inao
Chapter 1 Introduction
Chapter 2 Moist air properties and conditioning processes
Chapter 3 Air-conditioning systems
Chapter 4 Indoor and outdoor design conditions
Chapter 5 Space air diffusion and duct design
Chapter 6 Heat transmission in building structures
Chapter 7 Solar radiation
Chapter 8 Infiltration and ventilation
Chapter 9 Cooling/heating load calculations
Chapter 10 Building energy calculations
Nme 516 industrial processes for canvasCharlton Inao
The course involves the study and analysis of of industrial processing plants, focusing on local and international industries . It also deals with the analysis of flow sheets, equipment and operating data from simple cone-type rice mills, coconut oil mills, sugar centrals, plywood factories, cement plants to big power plants and processing plants.analysis of flow sheets, equipment and operating data from simple cone-type rice mills, coconut oil mills, sugar centrals, plywood factories, cement plants to big power plants and processing plants.
Nme 3107 technopreneurship for canvas june 17Charlton Inao
Technopreneurship is a philosophy, a way of building a career or perspective in life. The course covers the value of professional and life skills in entrepreneurial thought, investment decisions, and action that students can utilize in starting technology companies or exexuting R&D projects in companies as they start their careers.The net result is a positive outlook towards wealth creation, high value adding, and wellness in society.
KuberTENes Birthday Bash Guadalajara - K8sGPT first impressionsVictor Morales
K8sGPT is a tool that analyzes and diagnoses Kubernetes clusters. This presentation was used to share the requirements and dependencies to deploy K8sGPT in a local environment.
Harnessing WebAssembly for Real-time Stateless Streaming PipelinesChristina Lin
Traditionally, dealing with real-time data pipelines has involved significant overhead, even for straightforward tasks like data transformation or masking. However, in this talk, we’ll venture into the dynamic realm of WebAssembly (WASM) and discover how it can revolutionize the creation of stateless streaming pipelines within a Kafka (Redpanda) broker. These pipelines are adept at managing low-latency, high-data-volume scenarios.
Water billing management system project report.pdfKamal Acharya
Our project entitled “Water Billing Management System” aims is to generate Water bill with all the charges and penalty. Manual system that is employed is extremely laborious and quite inadequate. It only makes the process more difficult and hard.
The aim of our project is to develop a system that is meant to partially computerize the work performed in the Water Board like generating monthly Water bill, record of consuming unit of water, store record of the customer and previous unpaid record.
We used HTML/PHP as front end and MYSQL as back end for developing our project. HTML is primarily a visual design environment. We can create a android application by designing the form and that make up the user interface. Adding android application code to the form and the objects such as buttons and text boxes on them and adding any required support code in additional modular.
MySQL is free open source database that facilitates the effective management of the databases by connecting them to the software. It is a stable ,reliable and the powerful solution with the advanced features and advantages which are as follows: Data Security.MySQL is free open source database that facilitates the effective management of the databases by connecting them to the software.
Online aptitude test management system project report.pdfKamal Acharya
The purpose of on-line aptitude test system is to take online test in an efficient manner and no time wasting for checking the paper. The main objective of on-line aptitude test system is to efficiently evaluate the candidate thoroughly through a fully automated system that not only saves lot of time but also gives fast results. For students they give papers according to their convenience and time and there is no need of using extra thing like paper, pen etc. This can be used in educational institutions as well as in corporate world. Can be used anywhere any time as it is a web based application (user Location doesn’t matter). No restriction that examiner has to be present when the candidate takes the test.
Every time when lecturers/professors need to conduct examinations they have to sit down think about the questions and then create a whole new set of questions for each and every exam. In some cases the professor may want to give an open book online exam that is the student can take the exam any time anywhere, but the student might have to answer the questions in a limited time period. The professor may want to change the sequence of questions for every student. The problem that a student has is whenever a date for the exam is declared the student has to take it and there is no way he can take it at some other time. This project will create an interface for the examiner to create and store questions in a repository. It will also create an interface for the student to take examinations at his convenience and the questions and/or exams may be timed. Thereby creating an application which can be used by examiners and examinee’s simultaneously.
Examination System is very useful for Teachers/Professors. As in the teaching profession, you are responsible for writing question papers. In the conventional method, you write the question paper on paper, keep question papers separate from answers and all this information you have to keep in a locker to avoid unauthorized access. Using the Examination System you can create a question paper and everything will be written to a single exam file in encrypted format. You can set the General and Administrator password to avoid unauthorized access to your question paper. Every time you start the examination, the program shuffles all the questions and selects them randomly from the database, which reduces the chances of memorizing the questions.
HEAP SORT ILLUSTRATED WITH HEAPIFY, BUILD HEAP FOR DYNAMIC ARRAYS.
Heap sort is a comparison-based sorting technique based on Binary Heap data structure. It is similar to the selection sort where we first find the minimum element and place the minimum element at the beginning. Repeat the same process for the remaining elements.
NUMERICAL SIMULATIONS OF HEAT AND MASS TRANSFER IN CONDENSING HEAT EXCHANGERS...ssuser7dcef0
Power plants release a large amount of water vapor into the
atmosphere through the stack. The flue gas can be a potential
source for obtaining much needed cooling water for a power
plant. If a power plant could recover and reuse a portion of this
moisture, it could reduce its total cooling water intake
requirement. One of the most practical way to recover water
from flue gas is to use a condensing heat exchanger. The power
plant could also recover latent heat due to condensation as well
as sensible heat due to lowering the flue gas exit temperature.
Additionally, harmful acids released from the stack can be
reduced in a condensing heat exchanger by acid condensation. reduced in a condensing heat exchanger by acid condensation.
Condensation of vapors in flue gas is a complicated
phenomenon since heat and mass transfer of water vapor and
various acids simultaneously occur in the presence of noncondensable
gases such as nitrogen and oxygen. Design of a
condenser depends on the knowledge and understanding of the
heat and mass transfer processes. A computer program for
numerical simulations of water (H2O) and sulfuric acid (H2SO4)
condensation in a flue gas condensing heat exchanger was
developed using MATLAB. Governing equations based on
mass and energy balances for the system were derived to
predict variables such as flue gas exit temperature, cooling
water outlet temperature, mole fraction and condensation rates
of water and sulfuric acid vapors. The equations were solved
using an iterative solution technique with calculations of heat
and mass transfer coefficients and physical properties.
ACEP Magazine edition 4th launched on 05.06.2024Rahul
This document provides information about the third edition of the magazine "Sthapatya" published by the Association of Civil Engineers (Practicing) Aurangabad. It includes messages from current and past presidents of ACEP, memories and photos from past ACEP events, information on life time achievement awards given by ACEP, and a technical article on concrete maintenance, repairs and strengthening. The document highlights activities of ACEP and provides a technical educational article for members.
A review on techniques and modelling methodologies used for checking electrom...nooriasukmaningtyas
The proper function of the integrated circuit (IC) in an inhibiting electromagnetic environment has always been a serious concern throughout the decades of revolution in the world of electronics, from disjunct devices to today’s integrated circuit technology, where billions of transistors are combined on a single chip. The automotive industry and smart vehicles in particular, are confronting design issues such as being prone to electromagnetic interference (EMI). Electronic control devices calculate incorrect outputs because of EMI and sensors give misleading values which can prove fatal in case of automotives. In this paper, the authors have non exhaustively tried to review research work concerned with the investigation of EMI in ICs and prediction of this EMI using various modelling methodologies and measurement setups.
3. Nonlinearities
A linear system possesses two properties:
superposition and homogeneity.
• The property of superposition means that the output response of
a system to the sum of inputs is the sum of the responses to the
individual inputs.
Thus, if an input of r1(t) yields an output of c1(t) and
an input of r2(t) yields an output of c2(t), then an input of r1(t) +
r2(t) yields an output of c1(t) + c2(t).
• The property of homogeneity describes the response of the
system to a multiplication of the input by a scalar.
Specifically, in a linear system, the property of
homogeneity is demonstrated if for an input of r1(t) that yields an
output of c1(t), an input of Ar1(t) yields an output of Ac1(t); that
is, multiplication of an input by a scalar yields a response that is
multiplied by the same scalar.
4. We can visualize linearity as shown in Figure 6. Figure 6(a) is a
linear system where the output is always ½ of the input, or f(x) = 0.5X:,
regardless of the value of X, Thus each of the two properties of linear
systems applies.
For example, an input of 1 yields an output of ½ and an input of 2 yields an
output of 1. Using superposition, an input that is the sum of the original
inputs, or 3, should yield an output that is the sum of the individual outputs,
or 1.5. From Figure 6(a), an input of 3 does indeed yield an output of 1.5.
FIGURE 6 a. Linear system; b. nonlinear system
To test the property of
homogeneity, assume an
input of 2, which yields an
output of 1. Multiplying this
input by 2 should yield an
output of twice as much, or 2.
From Figure 6(a), an input of
4 does indeed yield an output
of 2. The reader can verify
that the properties of linearity
certainly do not apply to the
relationship shown in Figure
6(b).
5. Figure 7 shows some examples of physical nonlinearities.
An electronic amplifier is linear over a specific range but
exhibits the nonlinearity called saturation at high input
voltages.
A motor that does not respond at very low input voltages
due to frictional forces exhibits a nonlinearity called dead
zone.
Gears that do not fit tightly exhibit a nonlinearity called
backlash: The input moves over a small range without the
output responding.
The reader should verify that the curves shown in Figure 7
do not fit the definitions of linearity over their entire range.
6. FIGURE 7 Some physical nonlinearities
increasing
decreasing
8. A designer can often make a linear approximation to a
nonlinear system. Linear approximations simplify the analysis
and design of a system and are used as long as the results
yield a good approximation to reality.
For example, a linear relationship can be established at
a point on the nonlinear curve if the range of input values
about that point is small and the origin is translated to that
point.
Electronic amplifiers are an example of physical
devices that perform linear amplification with small excursions
about a point.
9. Linearization
The electrical and mechanical systems covered
thus far were assumed to be linear. However,
if any nonlinear components are present, we
must linearize the system before we can find
the transfer function. After discussing and
defining nonlinearities non-linearities, we
show how to obtain linear approximations to
nonlinear systems in order to obtain transfer
functions or to model a physical system.
10. The first step is to recognize the nonlinear component and
write the nonlinear differential equation. When we linearize a
nonlinear differential equation, we linearize it for small-signal inputs
about the steady-state solution when the small-signal input is equal
to zero. This steady-state solution is called equilibrium and is
selected as the second step in the linearization process. For
example, when a pendulum is at rest, it is at equilibrium. The
angular displacement is described by a nonlinear differential
equation, but it can be expressed with a linear differential equation
for small excursions about this equilibrium point.
Next we linearize the nonlinear differential equation, and then
we take the Laplace transform of the linearized differential equation,
assuming zero initial conditions. Finally, we separate input and output
variables and form the transfer function. Let us first see how to
linearize a function; later, we will apply the method to the linearization
of a differential equation.
12. If we assume a nonlinear system operating at point A, [x0, f(x0)] in Figure
8, small changes in the input can be related to changes in the output about
the point by way of the slope of the curve at the point A. Thus, if the slope
of the curve at point A is ma, then small excursions of the input about point
A, δx, yield small changes in the output, δf(x), related by the slope at point
A. Thus,
FIGURE 8 Linearization about points
Eq. 3.0
Eq. 3.1
Eq. 3.2
This relationship is shown graphically in
Figure 8, where a new set of axes, δx
and δf(x), is created at the point A, and
f(x) is approximately equal to f(x0), the
ordinate of the new origin, plus small
excursions, maδx, away from point A.
15. Example: Linearizing a Function
Sample 1: Linearize f(x) = 5cosx about x=π/2.
SOLUTION:
• We first find that the derivative of f(x) is df/dx=(-
5sinx). At x=π/2, the derivative is -5. Also f(x0) =
f(π /2) = 5cos(π/2) = 0. Thus, from Eq. (3.2), the
system can be represented as f(x) = -5δx for small
excursions of x about π/2. The process is shown
graphically in Figure 9, where the cosine curve
does indeed look like a straight line of slope -5
near π/2.
17. The previous discussion can be formalized using the Taylor series
expansion, which expresses the value of a function in terms of the value of that
function at a particular point, the excursion away from that point, and derivatives
evaluated at that point. The Taylor series is shown in Eq. (3.3).
Eq.3.3
For small excursions of x from xo, we can neglect higher-order
terms. The resulting approximation yields a straight-line relationship between the
change in f(x) and the excursions away from XQ. Neglecting the higher-order
terms in Eq. (3.3), we get
Eq. 3.4
or
Eq. 35.
which is a linear relationship between δf(x)
and δx for small excursions away from x0.
It is interesting to note that Eqs. (3.4) and
(3.5) are identical to Eqs. (3.0) and (3.1),
which we derived intuitively.