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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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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30 votes
6 answers
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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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6 votes
3 answers
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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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2 votes
1 answer
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Relationship between switching frequency and controller's crossover frequency in buck SMPS

Context: tuning the control loop of a buck SMPS. I specicifally have a TI TPS40200-based circuit in mind, but I think this applies to SMPS design in general. Quoting from Type 2 compensation network: ...
Dmitri's user avatar
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19 votes
2 answers
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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 ...
Adam Haun's user avatar
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12 votes
4 answers
11k views

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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5 votes
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zero of spring-mass system

I was reading this PDF which tries to explain the concept of poles and zeros of Laplace transform. I started with second paragraph on page #590 and read it up to page #592 before the new section "...
PG1995's user avatar
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3 answers
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Switching frequency and controller's crossover frequency in DC-DC converters

In the context of control loop stability of DC-DC Converters, A switch mode power supply is essentially a sampled-data system, therefore the theoretical maximum bandwidth is one half the switching ...
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PID controller slowly oscillates out of control

I am trying to tune PID controllers for my drone. There are 3 controllers, one each for Pitch, Yaw and Roll. I have gotten Yaw tuned to a reasonable amount and I am assuming the values for Kp, Ki and ...
Plasmabot's user avatar
2 votes
1 answer
204 views

Input filter transfer function derivation

In the figure above, I am trying to design an input filter that attenuates all switching frequency harmonics from i_sys, such that i_batt is a DC current with vary small ripples. My approach is to get ...
amidher'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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3 answers
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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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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
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
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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5 votes
4 answers
3k views

How to mount electronics on a vehicle chassis safely

I want to implement a control system I designed for a light electric motorbike. I would like to mount it as professionally as possible on the chassis. It consists of a power system pcb and a SAMC21 ...
Eliott W's user avatar
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5 votes
3 answers
12k views

Detecting dry-running of water pump

What are some reasonably reliable ways of detecting that a water pump (electrical motor based) is "dry running", i.e. no water is passing through the pump either because there is no water available at ...
bdutta74's user avatar
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5 votes
5 answers
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Laplace transform and the idea of frequency domain analysis

I have studied control theory in depth in my undergrad and still continue to use it on many occasions in my PhD work, but i still don't fully understand why we call Laplace transformation of system a "...
Udai F.mHd's user avatar
5 votes
1 answer
686 views

Effect of zeroes in system stability

Suppose we have two third order systems (a and b), with three poles and two zeroes,poles for both the systems are at the same positions in frequency domain but these systems differ in the placement of ...
sarthak's user avatar
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4 votes
2 answers
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Effect of right half plane zero on bandwidth of control system

It is known that the right half zero and the delay limit the achievable bandwidth of a control system. Can someone please explain the reason, how the right half plane zero limits the achievable ...
SaJ's user avatar
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3 answers
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Confusion in understanding control system?

I am learning basics of control systems from following link http://instrumentationandcontrollers.blogspot.com/2010/11/types-of-control-systems.html It says that automatic washing machine & ...
DSP_CS's user avatar
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3 votes
5 answers
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System response types

Whenever I am given a system type with a certain transfer function, I am always asked to proceed to find out the 1. impulse response and 2. step response of the system. My question is, what is so ...
ubuntu_noob's user avatar
3 votes
3 answers
357 views

BIBO and impulsive stability in voltage-controlled electrical circuits

Branching from the comments here, TimWescott gave this example of an open-loop unstable electrical system: Find the nearest NPN power transistor. Put it in a circuit with a healthy (for it) voltage ...
Mauro's user avatar
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2 votes
2 answers
394 views

Power Supply : How to keep SMPS always above the post-regulator that follows it

I'm trying to find a way of building a new power supply for my workshop, in order to keep it small and not so hot I will be using a spare xformer to step down mains to 24v and then a variable buck ...
k_orolev's user avatar
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2 votes
1 answer
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Mathematical model of the temperature of resistors/heatsinks?

I want to model the transfer function of a resistor mathematically, and am after some resources / tips on if it's possible to do so. For example, if I put 1V into a 1 Ohm resistor, I want to know how ...
tgun926's user avatar
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1 vote
2 answers
451 views

PR controller electrical circuit

I am attempting to design a PR control feedback loop for a grid tie inverter. The math checks out but I can't seem to convert the transfer function and/or block diagram into an actual electrical ...
Ande Mandoyi's user avatar
1 vote
2 answers
1k 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 ...
Leoc's user avatar
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0 votes
1 answer
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How to go about determing the System Type of my setup?

I have a small project where I am PID tuning two servo motors. Something very similar to this: I am interested in finding the system type of the above setup, which includes the PID loop I have tuned. ...
rrz0's user avatar
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-1 votes
3 answers
410 views

Transistor current control with positive feedback differential amplifier

Hi Folks, I want to analyse the functionality of following OpAmp configuration which seems to be employed as voltage - current conversion. Positive feedback (This is not a Failure and is ...
HerrderElektronik's user avatar
25 votes
6 answers
11k views

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
2 answers
1k views

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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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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10 votes
3 answers
2k views

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
9 votes
2 answers
6k views

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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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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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
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
5 votes
4 answers
572 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 ...
Payton Grenich's user avatar
4 votes
3 answers
402 views

Frequency analyzer for loop gain measurement - Why should the injection point have low output impedance and high input impedance?

@5:08 The video mentions: "The insertion point should have a low output impedance and high input impedance" What is the background for this condition?
Dynamic_equilibrium's user avatar
4 votes
2 answers
4k views

Systems stability with zero poles

I have a rather simple question I would say. I know that systems having real poles to the right side of the plane will inevitably be instable (for LTI systems at least). But I'm confused with ...
Yannick's user avatar
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4 votes
1 answer
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Can a phase margin become bigger than 180° and is this bad?

I have a wrong mental model about phase margin in control theory. I see that a phase of -180° is bad. If my input is a sine wave and I have negative feedback, which has a -180° phase shift, the ...
Mr.Sh4nnon's user avatar
3 votes
2 answers
5k views

How to find the state-variable equations from the signal flow graph of the system?

How to find the state-variable equations, i.e, the state equation & the output equation for the system described by the signal flow graph below?
avngr's user avatar
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3 votes
3 answers
25k views

What does it mean to have a pole or zero at infinity?

what does it signify ? At pole/zero frequencies the response of a system goes to infinity/zero, so I think same is the case with poles/zeros at infinity, but how do these poles/zeros affect the design ...
Salman Azmat's user avatar
3 votes
1 answer
2k views

Why fast inner current loop and slow outer loop of DC-DC converter

Let say we have a DC-DC converter operating with double loop control (inner and outer), and with switching frequency of Fs=20 kHz. Please, if you could answer the two following questions: Usually, ...
Ali's user avatar
  • 101
3 votes
2 answers
161 views

Power converter: Why we always focus on loop gain involving control to output transfer function?

While measuring loop gain using AP300 frequency analyzer, why we always focus on loop gain involving control to output transfer function? Is it because input to output transfer depends on power stage ...
Dynamic_equilibrium's user avatar
3 votes
2 answers
2k views

Does the concept of damping apply to 1st order systems?

I'm just learning control systems. Today I learnt about 1st order and second order systems. I understood Damping, Critically damped, over-damped and under-damped systems. So a question arises in my ...
Rishikesh's user avatar
  • 103
3 votes
2 answers
4k views

Proportional controller

Sirs, I am not able to understand why Proportional controller introduces offset.Please consider follwing paragraph I found on internet, credit to ** http://blog.opticontrols.com/archives/344 **, ...
Aditya's user avatar
  • 97
3 votes
3 answers
4k views

Intuitive understanding of relation between phase margin and peak overshoot and/or damping factor [closed]

Second, percent overshoot is reduced by increasing the phase margin, and the speed of the response is increased by increasing the bandwidth. "Control Systems Engineering, Norman S. Nise" ...
aviral upadhyay's user avatar