Questions tagged [control-system]

A control system regulates the behavior of other devices or systems, usually using a control loop. Examples are a home heating controller using a thermostat, a regulator keeping a drone stable, and industrial control systems used for controlling processes or machines.

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What is noise gain, really? And how is it determined in the general case?

UPDATE: This question triggered what might fairly be called a research obsession for me. I've gotten pretty close to the bottom of it I think, I've posted my findings as an answer below. There was a ...
scanny's user avatar
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25 votes
6 answers
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How to learn PID Control?

I want to learn PID (Proportional–Integral–Derivative) control mainly for temperature. I would like to learn preferably through an easy project to do. Could you please recommend something which ...
Daniel Grillo's user avatar
20 votes
13 answers
10k views

Why only sine waves?

I have already read a few EE texts where a sine wave is often seen. Why is the sine wave often used as a test function for a circuit or a system? Why don't we use any other signal instead of sine? ...
DSP_CS's user avatar
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19 votes
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How to use measured step response to tune control system

How does one use a measured step response to tune either a PID or convolution control scheme? Inspired by this answer*, I'm interested a more detailed explanation of how to implement a control system ...
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Why are low-dropout (LDO) voltage regulators unstable?

LDO regulators based on P-type transistors seem to be the preferred form of linear voltage regulator today, but I keep hearing about how I have to choose the output capacitor(s) carefully to guarantee ...
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System Modeling for Control Systems

After taking classes in control theory as an undergraduate, I ended up not using them at all after I graduated. I've started to fix that by starting a hobby project in controls. My textbooks are ...
krapht's user avatar
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11 answers
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Do working electrical engineers in circuit design ever use textbook formulas for rise time, peak time, settling time, etc

This is a very general question. In undergrad electrical engineering, students are usually taught about step response to LC (second order) circuits. This is usually when many parameters are ...
Fraïssé's user avatar
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17 votes
6 answers
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PID algorithm: how to account for fast input value changes after a long delay

I am trying to implement a basic PID algorithm on an Arduino Leonardo to mix hot and cold tap water using servo-controlled valves. The goal is to hold the temperature as close to a setpoint as ...
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17 votes
5 answers
17k views

How to implement a self tuning PID-like Controller

I am trying to write a micro-controller program for controlling temperature in a system with the following characteristics: output can only be On or Off, with fixed cycle frequencies (~2-10 per hour) ...
MandoMando's user avatar
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15 votes
4 answers
2k views

Motor fader PID control

I'm trying to control a motorized fader (linear slide potentiometer) using an Arduino. PID control gives good results for "jumping" to a specific target position, but tracking ramps is a problem, it's ...
tttapa's user avatar
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2 answers
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How do I size the output capacitor for a DC bench power supply?

I'm designing a DC bench power supply and have come to the matter of choosing the output capacitor. I've identified a number of related design criteria, but I'm finding my reasoning still going a bit ...
scanny's user avatar
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14 votes
7 answers
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Gain margin and Phase Margin Physical Meaning

I have been trying to understand the physical concept of Gain and Phase Margin. What I understand about this is that a relative comparison around the critical point \$(-1,0)\$, which when converted ...
Fawaz's user avatar
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5 answers
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How do power grid systems supply power to new loads coming online?

I know that in a power system there are no energy storage elements. Due to this, as soon as power is generated by the generators it is transmitted to the end user where the power is utilized. Say a ...
Sandaru Akalanka's user avatar
12 votes
5 answers
14k views

Why is the frequency complex

When we take the Laplace transform of a function, why is the frequency (s) complex? I can not understand the significance of complex frequency. Please help or give some references.
ironstein's user avatar
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4 answers
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Conditional stability

I'm learning about op-amps and feedback and how feedback affects their stability. I've been reading about gain and phase margin and their uses when I came across this: I don't quite understand how ...
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11 votes
3 answers
2k views

PID Control Loops with large and unpredictable anomalies

Short Question Is there a common way to handle very large anomalies (order of magnitude) within an otherwise uniform control region? Background I am working on a control algorithm that drives a ...
Adam Lewis's user avatar
10 votes
3 answers
3k views

How to tune a PID controller to a nonlinear process

I have a nonlinear thermal process (nonlinear radiation becomes more and more present as temperature goes up) that I would like to tune a PID controller to. I'd like to control the temperature as ...
user42875's user avatar
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3 answers
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How does control theory apply to my real-world processor-controlled boost converter?

I have a limited understanding of control theory. I dealt with poles and zeroes and transfer functions in school. I've implemented several microprocessor-based control schemes for DC/DC converters. ...
Stephen Collings's user avatar
10 votes
2 answers
102k views

What is a "dry contact input"?

I'm a PC software guy, a newbie to electronics. Recently, I've got a project in which I need to source for a DAQ that can provide dry contact inputs to an interfacing digital output controller. The ...
Joshua's user avatar
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9 votes
5 answers
11k views

Kinetis vs STM32

I'm looking into a new industrial controls application, and from my searches I have narrowed it down to 2 microcontrollers that look to fit the application well. The STM32 and the Kinetis. They both ...
radix07's user avatar
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2 answers
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What is meant by "plant" in control system?

What is meant by "plant" in control system? Does it also means systems like DC motor or it only includes large systems like chemical (fertilizer or cement) plant?
DSP_CS's user avatar
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9 votes
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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 ...
rrz0's user avatar
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9 votes
1 answer
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Conversion of PID controller components with state feedback into single transfer function and discrete state-space form

I've been wrestling with this problem for about a week now, as a part of a year-long project. We're designing a controller for a specific reactor based on a model. After looking at this for a while, I ...
John Galt's user avatar
8 votes
3 answers
3k views

Confusion in PID loop for the case of zero error?

I am already studying PID control and some how to some extent I have understood it except one main confusion. When the difference between reference input \$r(t)\$ and current output value \$y(t)\$ is ...
DSP_CS's user avatar
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8 votes
4 answers
831 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 ...
alim1990's user avatar
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3 answers
1k views

What do the poles and zeros of a system physically represent?

I've been working with transfer functions and control models for a while, but I never really have gotten an intuitive understanding of what the poles and zeros of a system really represent. I was ...
your_best_friend's user avatar
8 votes
3 answers
3k views

Control theory: is there any actual application for D in ABCD matrix?

Recall that a LTI state space of a dynamical system is given as: Is there any actual purpose for D in the output equation? If D was not zero, it would mean that the output is "directly" dependent ...
Fraïssé's user avatar
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7 votes
4 answers
11k views

Why aren't Stepper motors used in closed-loop systems and PID control?

I know stepper motors are usually operated in open-loop systems. I'm curious to why they aren't usually part of closed-loop systems? Also why aren't PID control methods commonly used with stepper ...
user124757's user avatar
7 votes
3 answers
1k views

How do I explain this regulation action in terms of control theory?

Shown below is a current regulator circuit which ensures an almost constant current through R1 independent of Vin variations. There is no closed loop feedback system evident- How can we explain this ...
Dynamic_equilibrium's user avatar
7 votes
7 answers
22k views

Building a temperature-controlled water bath

I want to build an accurate (±2 °C) water heater (sous vide) that heats water somewhere between 30-100 °C according to user input. Although I have an engineering background I have no ...
Tarscher's user avatar
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7 votes
3 answers
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The term Feed-forward and its meaning?

I am trying to understand the technical meaning of the term 'feed-forward', when and where it can be used and where it cannot be used? I have seen this term in various different areas. For example: ...
alt-rose's user avatar
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7 votes
4 answers
2k views

Misconceptions about PID Controllers

I'm currently designing an equivalent of the mass-spring-dashpot system, and during the design phase I realized I don't fully understand how PID controllers physically work. Below is an image, the ...
anonymouse's user avatar
7 votes
3 answers
1k views

Can a DC motor with obstructed movement be damaged?

I am trying to build shades, which should roll up or down, controlled by a DC motor. This motor can only be turned on or off (1/0 to turn it on/off). Also, it should be noted that the microcontroller ...
jadkik94's user avatar
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7 votes
4 answers
3k views

How to design controllers "properly"?

It may sound like the "easy way" to ask it here, but this question (along with a couple others I've posted which were more specific) is the result of years of research on the topic - on and off as it'...
Mister Mystère's user avatar
7 votes
1 answer
513 views

Meaning of an arrow in the control scheme

I cannot understand what the arrow that goes through "internal model" block mean? how can I interpret what does it do? What is the difference from any other "normal" arrow? (source: cam.ac.uk)
caspik's user avatar
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7 votes
4 answers
18k views

deriving the transfer function given bode plot

I have been given the following question on finding the transfer function from the following bode plot I know that the transfer function should look like this \begin{equation} H\left(jw\right)\:=\:\...
JordenSH's user avatar
  • 299
7 votes
1 answer
984 views

Interpreting bode plot of type 3 compensation network for buck regulator

I'm struggling to design the type 3 compensation network for a simple buck PWM controller. The controller is a Richtek RT8110B. According to the datasheet, half of the type 3 network is in-built and ...
Dan Laks's user avatar
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7 votes
3 answers
5k views

Any open tool for graph plotting for determining PID tuning parameters?

I have gone through several PID implementations and its tuning tutorials, documents and all. The Best tuning tutorial was PID-without-a-PhD.pdf . But has not been of much help. I can say it works some....
Rick2047's user avatar
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6 votes
5 answers
7k views

Control one relay via multiple 12 V DC signals

I'm seeking help designing a circuit wherein we would have multiple 12 V DC signal inputs, with the goal of: ...
David B's user avatar
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6 votes
3 answers
26k views

over and critically damped systems settling time

I know that for second order systems the settling time(St) equation is: So my question is, should this same formula be used when the system is over or critically damped? Is it right to use it in that ...
gerard's user avatar
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6 votes
3 answers
4k views

Why is phase margin considered more important than gain margin in dc-dc converters?

Control theory text books say both gain margin and phase margin give information about relative stability. These quantities also give an idea about the corresponding closed loop system's transient ...
Dynamic_equilibrium's user avatar
6 votes
2 answers
1k views

What is this RC local feedback configuration?

I'm studying power converter control loops using Christophe Basso's book Designing Control Loops for Linear and Switching Power Supplies. A very common pattern in the compensator circuits is a ...
scanny's user avatar
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6 votes
3 answers
2k views

Why do digital controllers need A/D and D/A converters?

One of the questions in our final exam will be "Explain the need of A/D and D/A converters in digital controllers". I could not find the reason anywhere why the Plant part of a block diagram requires ...
gadelat's user avatar
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6 votes
3 answers
823 views

Why is the transfer function of this circuit first order, when it has two energy storage elements?

I have the following circuit (assuming an ideal opamp), simulate this circuit – Schematic created using CircuitLab which has a transfer function that looks something like $$ \frac{As + 1}{Bs + ...
Jadon Clugston's user avatar
6 votes
2 answers
3k views

Dimmer to bulb control

I need to control a bulb of 220V, with different intensity light levels. I've an Arduino Uno Board, which receives a variable voltage from a Light-to-voltage converter (TSL12S) (Like a photoresistance)...
Eduardo's user avatar
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6 votes
8 answers
3k views

Why are there only PID controllers, no PIIIDDD (higher order) controllers?

Transfer function of a PID controller is: \$I\cdot s + P+\dfrac{D}{s}\$ Are there controllers like: \$A\cdot s^2 + B\cdot s + C+\dfrac{D}{s} + \dfrac{E}{s^2}\$ ? If so, are they common? Why do ...
richieqianle's user avatar
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6 votes
3 answers
981 views

Confusion in block diagram of open loop and close loop control system?

I am studying Modern Control Systems, 11th edition, by Dorf and Bishop. On page 221 it first shows in fig4.7 open loop control system(the writer names it as open loop) and on page 222 close loop ...
DSP_CS's user avatar
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6 votes
2 answers
7k views

How I can set up a transfer function of y = mx+c?

I have a system governed by the following relationship: \$V_{OUT} = m * I_{IN} + 5\$ I need to write a transfer function for the equation. Would anyone please give me some suggestion of how to ...
Superhero's user avatar
  • 807
6 votes
1 answer
2k views

Type 2 compensation network

I'm working through the excellent text on SMPS design "Switching Power Supplies A to Z", by Sanjaya Maniktala. Right now I'm reading the section on the feedback loop and stabilization. As a first-...
MattyZ's user avatar
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6 votes
2 answers
2k views

Reverse engineering garage door opener signal

I have a new liftmaster (chamberlain) garage door opener that has a wired keypad. The keypad has several buttons on it, but for my purposes I'm only interested in the door open/close and light on/off ...
Paul Wieland's user avatar

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