Questions tagged [control-system]

A system that may be electronic circuits or even software that uses control theory (principally differential equations) to control an output by monitoring various aspects of the system under control and varying inputs all towards meeting a defined goal. Some famous examples are controlling a rockets thrust angle to ensure directional control.

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1answer
204 views

PI controller - DC voltage regulation

I a voltage source converter, in order to control the DC-Bus voltage a PI controller can be used. The control method is illustrated in the figure below: I would like to ask why the input of the PI ...
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745 views

Constructing bode plot from experimental data and constructing a transfer function

I've been trying for a few days to convert an experimentally obtained (frequency against magnitude and frequency against phase) graphs to a bode plot and then construct a transfer function from the ...
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42 views

How do you reduce this simple system diagram for the sake of doing algebraic manipulation?

My guess is that since H(s) is parallel with 1(s) we'd do A(H - 1)? But this is my first ...
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40 views

What are some techniques to troubleshoot a second order sigma delta loop?

I have designed a slightly modified second order (3-bit) multi-bit incremental sigma delta modulator (IDSM) in simulink (system level). The SNR that I get is 45dB, which is not as expected. But ...
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294 views

How to plot root loci in z plane

How to plot root loci of loop gain G(z)= k/(z-0.5)(z-0.5)(z-0.5) in z plane?
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243 views

How to use the Root Locus design method to improve the transient response of my system?

By closing the loop, I need to design a controller in the feedforward path to minimise the effects of the two pairs of dominant poles of the 5th order transfer function. Use a pole-zero cancellation ...
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1answer
244 views

rlocus() - Not enough input arguments in MATLAB 2018a

I am following this tutorial on root locus methods and when writing: syms s sys = 1/(3*s^2 + 2*s - 1); rlocus(sys) I get: Error using rlocus Not enough ...
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210 views

How do I calculate a PID controller gain for a certain damping coefficient?

I have a third order process and I have to design a PID controller by cancelling out the two most dominant poles of the process. The process transfer function is: The controller is of the form, where ...
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404 views

Steady state error due to disturbance

I was trying to solve a question from the 2004 GATE IN paper, I solved it this way, Now, the book is giving a different solution, I'm pretty sure my way is correct since they pulled the "standard ...
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220 views

Meaning of transfer function in s evaluated at a complex number

From the pole-zero plot, you can compute the system frequency response by assuming a locus of test points along the \$j\omega\$ axis. Figure from: http://web.mit.edu/2.14/www/Handouts/PoleZero.pdf \...
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101 views

Nyquist Stability Criteria

Find the stability where: Find the stability: \$ G(s)= \frac{(s+3)(s+5)}{(s-2)(s-4)}; \$ \$ H(s)= 1; \$ I run this code in matlab: ...
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309 views

Normalization of Pid Output

New to using PIDs. When normalizing a range, we would need to know the maximum and minimum of that range. Since a PID is summing the error in the I portion wouldn't the range be potentially infinite? ...
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77 views

Designing of a PID Controller

First of all, I am new to this Q/A site. If I am doing anything wrong, please forgive me. I am having some trouble solving this problem: Given the system of Figure(1), design a PID controller so that ...
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149 views

How do integrator circuits serve as memory devices in continuous time system?

I didn't understand the yellow-marked sentence clearly, and even I did, what does it have to do with the conclusion that follows it? (marked in green). Thanks in advance.. Source: Modern control ...
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30 views

Principle and generalization of proportional-resonance controller

simulate this circuit – Schematic created using CircuitLab We can introduce the model of \$u(s)\$ into the controller \$K(s)\$ to realize high accuracy control. \$u(t) = 1\$, i.e. \$u(s) = 1/...
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63 views

Finding PID parameters .. How?

As in the picture , how can I determine ki , kp , kd I tried (using provided data) by finding ζ and ωn But I end up with third order transfer function could not subsitute my results to find PID ...
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889 views

What is the relationship between a step input and an integrator?

While trying to understand control engineering from first principles I came across the following which I cannot yet explain intuitively or mathematically. What is the relationship, between a step ...
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41 views

Replacing Electrical System with a Gain?

I have a system containing both a mechanical and an electrical part, as shown in the block diagram below. I am interested in simplifying this block diagram by eliminating the electrical part and ...
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1answer
138 views

Pole placement to create a full-state feedback controller?

I am learning about control theory by going through Oagata's Modern Control Engineering. As part of a practice exercise I am trying to design a full-state feedback controller that satisfies my ...
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111 views

Determine the impulse response of the following discrete system

I'm not sure how they got the answer (provided below) for the following discrete system y[n] = x[n]- 2x[n-2]+ x[n-3]- 3x[n-4] the answer is given as .... h[n] = [1 0 -2 1 -3] why is this? any help ...
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597 views

Reducing the order of transfer function while maintaining same response

Scenario: I have been going through Ogata Modern Control Engineering book and working through several exercises to improve my understanding of basic control principles. I came across the following ...
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52 views

What is the meaning of the first gain in the block diagram?

I have do design a circuit based on the block diagram below. I know how to design the PID part but I don't understand what the K=2 is. For the PID I have made the following:
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1answer
1k views

Finding the Transfer Function of Spring Mass Damper System

I have been going through Ogata Modern Control Engineering book and working through several exercises to improve my understanding of basic control principles. I came across the following example which ...
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70 views

Dynamic Compensator in Control Loop

Sorry if this has been asked previously, but I couldn't find anything here or elsewhere on Google (but maybe I'm searching the wrong terms). I'm trying to design a Type 2 compensator for a PWM chip I'...
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3answers
303 views

Source of poles and zeros in a physical system?

From where does the poles and zeros come into the transfer function of any system? And I am not looking for an answer in terms of mathematics but want to know what is there in any physical system that ...
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101 views

Calculating the transfer function of this op-amp circuit

The first op-amp is a differential, second one is a follower and third one is a second order low pass filter. I've been struggling with the low pass and the final output of the circuit and I am not ...
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1answer
240 views

Gain of an experimental first order step response

I have a pwm driven DC motor control system with magnetic encoder that measures the output shaft speed and outputs the RPM values every 50ms over serial comms to plot a graph of RPM vs Time. The ...
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1answer
316 views

Degenerate circuit concept and its theoretical and practical implications

I came across with the term "degenerate circuit" when I was studying solving linear differential equations with Laplace transform. I have learned that a system is called degenerate when the ...
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3answers
691 views

State Space model for three-loop circuit

How do I choose the least number of state variables for the following circuit? I started out by assuming currents $$i_{1}, i_{2}, i_{3}$$ in each of the loops and applied KVL, which fetched me three ...
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64 views

Control Theorie: Drawing Transition Matrix Trajectories

Given a transition matrix like e.g. $$ \phi(t)=\begin{bmatrix} e^{-3t} & 0 \\ 0 & e^{-3t} \end{bmatrix} $$ What is the analytical way of drawing x(t) for two given starting points? I only ...
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3answers
268 views

why do most sensors have an electrical output, regardless of the physical nature of the variable being measured [closed]

I have been trying to figure out a explanation to this question, can someone explain this ?
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146 views

Feedback Error Equation

I am currently digging into some amplifier feedback analysis tools papers and literature. I found some "term" right at beginning of this topic that I don't quite understand. That is "...
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1answer
56 views

Method for selecting unique resistor values in all combinations

I do controls, and sometimes I want to monitor more dry contacts than I have digital inputs for. I'm cheap, and don't want to pay for more points, so sometimes I'll put some resistors in parallel ...
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1answer
543 views

Field Oriented Control Feed Forward Term

I implemented a Field Oriented Control (FOC) controller for a synchronous motor, which works already pretty good. Now the I-part of the PI controllers is necessary to achieve a good reference tracking,...
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2answers
88 views

Relationship between eigen values and state feedback

so lets suppose we have a state space model x[k+1] = Ax[k] + Bu[k] y[k] = Cx[k] + Bu[k] and we want to design a state feedback, assuming that the system is ...
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1answer
467 views

Discretizing a PID controller

I am discretizing the PID equation so we have this equation Now if we separate the integral term we get Applying backward euler method Now as we already have a differentiation , by applying ...
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1answer
71 views

Relation between dash pot and spring in forces when extracting a transfer function [closed]

If a spring load some energy and use it for opposing other forces, and a dash pot has a friction, physically the both shouldn't have the same force-displacement equation ? In most of dash pots, we ...
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2answers
1k views

Using mesh analysis to get the transfer function of electrical system

I am studying the book: Control system engineering for Norman S Nise. I left the college few years ago, and I forgot lots of thing about Kirchhof's laws (Voltage and current). I tried to solve the ...
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242 views

How to I go from generalized Transfer Function to generalized State Space, and back?

Question: How can I transform a generalized Transfer Function a generalized state space form (preferable with the First Companion Form), and back? For the sake of presenting an example, let us say ...
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2answers
4k views

How to determine the phase margin and transfer function of this bode plot?

I have some struggles to find the transfer function of this plot. We got the hint, that the "breaks" of slope can be assumed to be on vertical and horizontal lines. Also we should pay attention on the ...
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2answers
258 views

Meaning of the “pole” of a transfer function with time delay

I learned in basic control theory that we can determine the stability of an LTI system by the signs of the real part of the poles of its transfer function \$H(s)=\frac{N(s)}{D(s)}\$. For a rational ...
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4answers
245 views

PID Tuning Issue

I'm having issues tuning a PID controller - specifically the I-term. First - here's a little info about my system: I'm heating a coil (R ~= 1.8 Ohms) to 750°F. My power delivery system is working ...
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1answer
656 views

Solving the differential equation in control system engineering

While I am continuing my studies of the Norman S. Nise book about Control System Engineering, and while trying to solve exercises of chapter 1, I noticed that I am out of the scope of solving ...
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3answers
498 views

Block diagrams can be different and still works for the same system?

I am an telecommunications engineer who is working now as a programmer. At university we took a class on digital filters, Laplace transformation and working in the frequency and time domain. At the ...
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1answer
385 views

PID tuning without plant model

My aim is to keep temperature constant at a certain place. I don't have a mathematical model of the plant. Currently, PID is used with some fixed Kp, Ki, and Kd, and I want to optimize these ...
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3answers
3k views

Should cable shields be connected to earth ground, or to power supply negative?

I'm working on a PLC cabinet, and I'm wondering whether I should hook cable shields to earth ground, or to the power supply negative. I checked and the power supply DC output is isolated. There's no ...
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1answer
1k views

Three-phase thyristor rectifier - Minimum firing angle

Why is a minimum firing angle (>0, usually 5-15°) defined for three-phase thyristor rectifier? I would like a technical explanation. Thanks
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1answer
66 views

Why is this derivation of the unit step function in the Z-domain valid?

This source states that the unit step function in the Z-domain is \$\frac{z}{z-1}\$. However, in its derivation it states \$\sum_{k=0}^{\infty} z^{-k} = \frac{z}{z-1}\$. But doesn't that last ...
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501 views

Finding the transfer function of an non-inverting audio op-amp

I am just doing some independent re-search for myself in audio amplifier (CHIP AMPS) such as the LM1875. I want to learn more about how to compensate for audio chip amps and how their bode plot ...
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43 views

What's oscillatory instability in the delay differential equations?

Does DDE’s stability depend on forcing term and ODE’s stability does not depend?If yes, then is frequency analysis of stability applicable only to DDE and not ODE? In control systems, we study ...

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