Questions tagged [control-theory]

For questions about control theory as it relates to electrical engineering, which provides tools to design electronics so that a system's output(s) are driven to the correct state for given input(s) by ensuring stability, reducing steady state error, overshoot, etc. Consider using in conjunction with related tags such as "transfer-function", "stability", "feedback", "frequency-response", "step-response", "nyquist-plot", "phase-margin", etc., if applicable.

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For the equation below, how would I calculate the gain required for a settling time of 1 s?

The equation is: \$G=\dfrac{k(s+4)}{(s+1)(s^2+6s+13)}\$ How would I calculate the gain (k) required for a settling time of 1 s? By using \$ts=\dfrac{4}{(ωζk)}\$ the closest value I got was ...
Colonel Floppsie's user avatar
4 votes
2 answers
143 views

Isolation Topology in SMPS

I have been researching SMPS designs as a hobby recently and finally have the courage to build one for theoretical and practical understanding. I have chosen an isolated design looking at several ...
Vadim Belogorodsky's user avatar
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1 answer
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Order of Complexity

Generally, number of independent state variables (order of complexity of a system) is equal to the number of reactive elements in RLC network. But, if capacitor and voltage source loops are present ...
lakshmideep maddineni's user avatar
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1 answer
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Derive state space from initial value problem

I am given the following initial value problem \$ y^{(4)} - y = u \$ with \$ y^{(3)}(0)=0, \ddot{y}(0)=1, \dot{y}=1, y(0)=10 \$ and am supposed to calculate the state space in the usual form \begin{...
insertRandomName's user avatar
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2 answers
477 views

Assign Bode plots to Nyquist diagrams

How do I assign the following Bode plots to their corresponding Nyquist diagram? Can i tell the number of poles of the transfer function of the nyquist plot, by looking at w→infinity (from which of ...
insertRandomName's user avatar
1 vote
2 answers
329 views

Deriving a transfer function from Nyquist plot

I am given a half Nyquist plot and exercise as below I know how to plot a Nyquist curve for a given transfer function but I have trouble doing it the other way. I stumbled upon this post Deriving ...
insertRandomName's user avatar
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Controller for a automotive BLDC triphasic motor that takes into account Velocity, Acceleration and jerk

Problem Im in the autonomous driving department for formula student and due to the current pipeline the very last message that outputs from it is a message that contains Velocity, Acceleration and ...
Imeguras's user avatar
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2 votes
1 answer
235 views

Compensator design for control systems

Currently, I'm working on linear control course from Nise's book. In the root-locus design chapter, some methods were explained for lag and lead compensator design which uses root-locus properties. ...
Mert Celik's user avatar
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Routh Hurwitz Criterion for Stability

What do the rows of the Routh table represent? What is the significance of writing the powers of 's' in the zeroth column?
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Confused about how Loop 2 is defined

In one of my exercises, I am presented with the following circuit: We are asked first to write some loop equations for the circuit. Naturally, they are given to be defined as: What I cannot ...
nyquil43's user avatar
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3 answers
154 views

Finding closed loop interval of stability with open loop frequency response data

I have the following open-loop frequency response data of a system: Frequency (rad/s) Gain (dB) Phase (degrees) 0.0628 9.3080 -137.4711 0.1257 8.2370 -126.3069 0.2513 7.8477 -151.0235 0.6283 9....
Gustavo L.'s user avatar
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2 answers
270 views

What are the gain and phase margins from this Bode plot?

I thought I had a decent grip on how Bode plots work yet for this model that I am working on, I need to implement a lead or a lag compensator. A lead compensator, which I was thinking about ...
johnny_yes_papa's user avatar
-1 votes
2 answers
773 views

Contradictory relationship between quality factor and damping

I am studying control theory and mechanical vibrations. From control theory aspect, I know that bandwidth and response time is inversely proportional, which means bandwidth and damping as well. The ...
Tym's user avatar
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3 votes
1 answer
306 views

What is the practical advantage of root locus method in control system engineering? [closed]

Recently I learned about the topic. Decades ago, when no computational power was available for engineers, it was surely helpful in some way. But I do not understand what the advantage is nowadays, ...
MichaelW's user avatar
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2 answers
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Laplace of third-order lead-lag filter

For Butterworth low-pass filters, the Laplace function of the third-order filter is $$ H(s)= \frac {1}{\left(1+\frac{s}{\omega_c}\right)\left(1+\frac{s}{\omega_c}+\frac{s^2}{\omega_c^2}\right)} $$ ...
Manuel's user avatar
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2 answers
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Why is closed loop frequency response hard to determine?

I'm learning about frequency domain control design and one of its advantages is said to be that: one can deduce the closed loop behaviour of a system by (experimental) data on frequency response on ...
Jan Lynn's user avatar
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How to design a 2nd order LP active filter with differents responses?

I have been asked to design and simulate a 2nd order analog low pass filter having the responses of Butterworth, Chebyshev and Bessel. Im looking for guidance and suggestions,since I understand the ...
avelardo's user avatar
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3 answers
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Space State on SEP/Ex DC-Motor

I'm currently studying DC motors and I do have some doubts about the dynamics of it. As per explained on [Guru, B.S. and Hiziroglu, H.R., 2001. Electric machinery and transformers (Vol. 726). New York:...
Michel Rodrigues's user avatar
1 vote
1 answer
3k views

How can I calculate gain margin in this transfer function and the constant K?

This is the problem statement: There is a mechanical crane whose Transfer Function is shown. If it is implemented The automatic system shown, closing the loop and adding the G1 block (s), you are ...
JEAN LEONARDO 's user avatar
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0 answers
506 views

PWM frequency and control system sampling frequency in dc-dc converters

I am trying to control the output voltage of a simple dc-dc buck converter, which is digitally controlled. The output voltage is sampled, and the control algorithm is run, at every \$T_s\$ seconds, ...
Lello's user avatar
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6 votes
2 answers
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I'm confused a bit on basic control stuff for a PID controller

I'm doing a PID controller demonstration project in which heat is applied to a K type thermocouple and I'm supposed to maintain the temperature read at 50 °C using a PWM signal. I know the basic ...
BigRedMachine's user avatar
2 votes
0 answers
71 views

Control system -- closed-loop system problem

Given a closed-loop system as shown below: Suppose that \$x(t) = u(t)\$ and \$d(t)=0.5u(t)\$. Determine the output response of \$y(t)\$ and it's steady state at \$t\rightarrow \infty\$. I've tried to ...
who am i's user avatar
1 vote
3 answers
368 views

Nichols plot confusion

The transfer function is \$F(p)=10/(p^2+2p+1).\$ Using Wolfram Alpha, the Nichols plot shows that the argument \$\to -\pi\$ when \$\omega \to +\infty\$. However, calculating the argument on paper ...
A.Bukhari's user avatar
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Feedforward from measurable disturbance

Gff is chosen so that it completely cancels the disturbance (Gff = -Gv/P) and Lp < Lv. Is it easier to control if Tp < Tv or Tp > Tv. I am a little bit lost on how to begin here? Should I ...
LukasL's user avatar
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-1 votes
2 answers
106 views

Meaning of "Dynamics" in terms of control systems?

What is meant by "dynamics" in context of control systems? For example what is difference between the dynamics of an aeroplane and a car? This question below answers to some extent my ...
DSP_CS's user avatar
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127 views

Linearization of nonlinear plant with system identification in Matlab

I hope this question fits in here and there is someone who can maybe help me. I am new to control theory and I have a very complex Simulink model which is nonlinear. I want to have a linear ...
beowl1's user avatar
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3 answers
1k views

Decide P controller gain K so that phase margin is 50°

I need help finding the gain \$K\$ so that the phase margin for the system equals 50°. $$F(s) = K$$ $$G(s) = \dfrac{1}{(s+1)^2}$$ \$v\$ is a process disturbance sinusoid with amplitude 2.5 and ...
mati's user avatar
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2 votes
0 answers
131 views

From where does State space model equations come from?

I have a good basic understanding on classical control theory. Now I am studying modern control theory.I encountered the following equations as seen below. Online I have only been able to find ...
calculusnoob's user avatar
1 vote
1 answer
156 views

fast analytical technique identifying poles/zeros using degree of freedom

I encounter some engineers who can quickly spot poles and zeros in the circuit by identifying "degree of freedom". For example, a typical technical discussion goes like : "a miller ...
Eagle Shou's user avatar
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771 views

Determine range of proportional gain with given overshoot

I have given the open-loop transfer function $$ G_{ol} = 1.42 \frac{(s+3)^2+6^2}{(s-1)(s+2)((s+4)^2+4^2)} $$ The task I was given is determining the range of the proportional gain, which makes the ...
Th2mas's user avatar
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1 vote
2 answers
1k views

Tuning PID without transfer function

I'm very new to control theory and I am stuck at PID tuning. I have a given Simulink model but I do not know the transfer function. I want to use a PID to provide new input from the output of the ...
beowl1's user avatar
  • 21
0 votes
3 answers
236 views

Why do I need phase margin if I know the transfer function?

What is the point of examining the phase margin (or gain margin) for a closed-loop system if I can just solve for the transfer function. The transfer function will give any poles and zeros, which can ...
sgdsgyhetwaraw's user avatar
1 vote
1 answer
216 views

Linearization of nonlinear system

I have a nonlinear system described by: $$\begin{align} V\,\dot x_1 &= Q_1 C_1 - (Q_1+u)x_1 \\ V\,\dot x_2 &= C_2\,u -(Q_1+u)x_2 \\ y &= -\frac{\log{\left[(x_1-x_2)+|x_1-x_2|+4K\right]}...
Alexandros Lechouritis's user avatar
2 votes
2 answers
347 views

Steady-state Error Definition

In the textbooks and reference material which I have been using during my course on control systems, a common definition of steady-state error is as follows: $$E(s)=R(s)-C(s)$$ where E(s) is the error ...
Benjamin Crawford Ctrl-Alt-Tut's user avatar
0 votes
1 answer
337 views

Finding the overall transfer function and plotting root locus of a digital control system

I have started to learn about digital control theory and struggling with a particular diagram of a digital control system. The system is presented below: \$D(z)\$ is a digital compensator, \$G_{h0}\$ ...
rrz0's user avatar
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2 votes
2 answers
842 views

Nyquist stability criterion for positive feedback

it is known that the stability of a system with negative feedback may be analyzed through the Nyquist stability criterion, which is based on observing the number of turns around the point (-1;0) in ...
Kinka-Byo's user avatar
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1 vote
1 answer
97 views

Layman explanation of "dynamics" or "dynamic behaviour"

I often read the term dynamics or dynamic behaviour in electrical engineering especially in control systems course What is meant by it? Is it means that the system whose internal state/properties ...
DSP_CS's user avatar
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548 views

What will be minimum number of states / state variables for these control systems in state-space model?

Consider the systems as LTI and SISO with transfer functions given below: I have read that minimum number of states for an LTI SISO system required to represent in state space analysis for any ...
SUNITA GUPTA's user avatar
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1 answer
268 views

555 square wave generation with frequency feedback

Knowing that 555's behaviour varies according to temperature, I wondered: In an astable configuration, is there some way to measure output frequency, compare it with some desired value, and use this ...
Iaka Noe's user avatar
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1 vote
1 answer
107 views

Feedback Circuit schematic to Control Theory block diagram?

I'm studying analog electronics circuit with feedback. I see that, during analysis, a useful abstraction over the schematic is the block diagram in control theory style, but I stuggle in deriving it ...
a_bet's user avatar
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0 votes
1 answer
51 views

Nomenclature for changing characteristic curve

OK, I'm at a loss for words on this one. I'm looking for a word or phrase to describe the following situation... I have an open loop control system that when I apply voltage \$A\$ I get output \$A_1\...
dave's user avatar
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0 votes
0 answers
567 views

Transfer function with separate time delays in each term

We've been given the problem below for our current assignment As far as I can recall, I have never seen a transfer function with time units in the function itself, added onto each separate term. I ...
user2687408's user avatar
0 votes
1 answer
179 views

Looking for a quote on dynamic system identification

Does anyone know of a quote by an eminent control theorist or controls engineer or book author who I could reference who said something along the lines of the following: The process of control ...
Bill's user avatar
  • 238
0 votes
4 answers
4k views

Effect of RHP zeros on stability

Why do zeros in the right half of the \$s\$ plane reduce stability (i.e., gain / phase margin)?
TVV's user avatar
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0 votes
1 answer
3k views

Determining Number of states in State Space Modeling

I want to use state space modeling for representing the following circuit system. However, I am unable to decide the number of states. I am able to describe the system with a set of three equations. ...
user avatar
0 votes
1 answer
289 views

How to calculate roots using root locus method? [closed]

Find the roots of the following polynomial by use of the root locus method. 3s⁴ + 10s³ + 21s² + 24s + 30 = 0 (The root locus plot has not been given.) Can you please help me with this? This ...
Jarvis1997's user avatar
5 votes
2 answers
7k views

Integral only control (as opposed to PI or PID)

I am familiar with PI and PID control but I've recently been reviewing code that seems to use I (Integral) only control. What are the benefits of I control over PI control, and when should it be used /...
Peter's user avatar
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0 votes
1 answer
380 views

Bode Plots - Absolute Value of Complex Function in Magnitude calculation

I'm struggling with one step in the magnitude calculation during manual Bode plotting. Specifically during the step of applying the absolute value to \$s = jw\$, what is the reasoning for why you can ...
Splotsmeister's user avatar
0 votes
1 answer
121 views

Control system error based on differential process value

In a basic PID controller, you measure the process value y (such as temperature) directly; then the error e is equal to the difference between the process value and the set point r. The error feeds a ...
Reinderien's user avatar
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1 vote
1 answer
607 views

Op-amp control theory

back at it again trying to use your genius brains. I have been trying to teach myself audio amplifier design. The big road block I am getting into is the control theory part of it, meaning how does ...
Leoc's user avatar
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