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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26
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5answers
10k 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 ...
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6answers
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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 ...
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11answers
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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 ...
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2answers
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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 ...
17
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4answers
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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 ...
15
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2answers
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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 ...
15
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6answers
2k views

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 ...
15
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4answers
1k 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 ...
14
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5answers
14k 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) ...
14
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2answers
2k views

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 ...
11
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7answers
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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 ...
11
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4answers
8k 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 ...
10
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3answers
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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. ...
10
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3answers
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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 ...
10
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1answer
613 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 ...
9
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1answer
2k views

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 ...
8
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3answers
2k 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 ...
8
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5answers
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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 ...
8
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4answers
2k 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'...
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2answers
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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 ...
7
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4answers
6k 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 ...
7
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7answers
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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 ...
7
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3answers
887 views

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: ...
7
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3answers
479 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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4answers
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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 ...
7
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3answers
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 ...
7
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1answer
356 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)
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3answers
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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....
6
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3answers
2k views

Confusion in PID loop?

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 zero, e(...
6
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2answers
509 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 ...
6
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2answers
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)...
6
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3answers
236 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 ...
6
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4answers
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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)\:=\:\...
6
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1answer
524 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 ...
6
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1answer
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-...
6
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4answers
574 views

Circuit Analysis: Obtaining Close Loop OP - AMP Transfer function

Trying to figure out the Close Loop System transfer function of an op-amp, however the math isn't working out as it should. Circuit In question: simulate this circuit – Schematic created using ...
6
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3answers
725 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 ...
5
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4answers
2k 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 ...
5
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3answers
642 views

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 & ...
5
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5answers
449 views

M.S. Math to Engineering Ph.D : Mathematics in Electrical Engineering [closed]

I have two Bachelor's degrees. One is electrical engineering and the other one is mathematics. I am studying mathematics (partial differential equations) in the graduate school (Master course) now. ...
5
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7answers
1k views

Control theory basics

I'm trying to understand something very basic about Control Theory. Let's say I have the following loop: If we'll relate this loop to a cart with a motor going in its single axis from X = 0 to X = 50,...
5
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2answers
454 views

Confusion regarding control system of a Mars rover

I am studying Modern Control Systems, 11th edition, by Dorf and Bishop. In its fourth chapter, it discusses design examples and one example is of a Mars rover. In that example, I am confused by the ...
5
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3answers
1k 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 ...
5
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3answers
499 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 ...
5
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3answers
1k views

How to build a precise voltage controlled resistive heater?

I have been tasked to build a heater for an industrial application. The heater uses resistance to heat the liquid and the application needs very precise control of temperature (+/- 1 degree). Existing ...
5
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1answer
4k 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 ...
5
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1answer
464 views

Using impulse response to control the system

This post by Olin Lathrop is rather inspiring. The system response is the convolution of the control input with this impulse response, computed every control sample, which is every 500 ms in ...
5
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1answer
388 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 ...
5
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2answers
162 views

Types and regulation schemes LDOs

LDOs, or low-dropout linear regulators, come in various types, but it can be difficult to distinguish them, and to the novice engineer, this regulator is often made to seem deceptively simple. Some ...
5
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3answers
643 views

Help finding transfer function for root locus using Matlab

I'd like to pick \$k_d\$ using root locus method, but have problems deriving the necessary transfer function of the system presented below. Assume \$k_p\$ is fixed. The question originates from Randal ...