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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2answers
40 views

Level system of water tank?feedback of close loop? [duplicate]

I have attached a photo from animation from following link https://beta.spiraxsarco.com/learn-about-steam/basic-control-theory/basic-control-theory this photo shows a float in a water tank, it ...
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1answer
269 views

How to test PLL for step input change in phase

I wrote a simulation for second-order PLL and I would like to test it with an input to see whether my PLL can track the phase. I would like to change the phase of my sinusoidal signal with step with ...
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57 views

Transient Response and s-plane root location

A second-order system has the closed-loop transfer function T(s)=Y(s)/R(s). The system specifications for a unit step input is as follows: I managed to solve the problem until this step. But I am ...
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908 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: ...
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2answers
410 views

Mechanical time constant of PMDC Motor in starting and after switching off the supply is same or different?

In my MATLAB/SIMULINK model of the PMDC motor the mechanical time constant has same value in the case starting of motor and after switching off the supply but in experimental setup there is a ...
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1answer
496 views

FOC current control autotuning PI Controller for BLDC Motors

I try to understand, how the guys from odrive tuned the current control PI parameters for Field Oriented Control: https://github.com/madcowswe/ODrive/blob/master/Firmware/MotorControl/low_level.c In ...
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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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1answer
69 views

Control theory in PLC (programmable logic controller)? [closed]

What is the control theory of PLCs (programmable logic controller)? PLCs fall in category of linear control or non linear control?
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43 views

Nonlinear Observer Question for BLDC

I'm looking at the article posted here, and I'm trying to figure out what it is that they're controlling and how. Specifically, Dave Wilson from TI gave a presentation called "Teaching Old Motors New ...
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1answer
197 views

Can my PID controller have negative p value and positive i value for a PID logic

I am building my first PID controller. My process variable and my actuator value are inversly related, meaning if actuator value increases process variable decreases, and vice versa. So I have tried ...
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1answer
179 views

What's the best starting point for rotor angle estimation for FOC?

I'm driving a BLDC motor with FOC. Right now, I have Space Vector modulation working, where I can give it a magnitude and an angle, and the algorithm will drop the right values into three PWM ...
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1answer
686 views

Control Engineering: Why are the Equation Error and Output Error different?

When modelling a system you must first estimate the form of the transfer function (order, time delay etc.), and then estimate the parameters (coefficients for the transfer function). A common way to ...
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2k views

How to find the intersection point in rootlocus diagram?

Question: Sketch the root locus for the open loop transfer function of a unity feedback control sytem given below and determine the value of K for \$\xi=0.5\$ \$G(s)=\frac{K}{s(s+1)(s+3)}\$ --...
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174 views

Why linearise around an equilibrium point?

In the control theory dealt in class I was taught to always linearise a nonlinear system around an equilibrium point, i.e., where $$\dot x = 0$$ However, linearization is a Taylor series expansion, ...
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4answers
22k views

Exact definition of overshoot

I am a computational biologist and am working on some aspects of control theory in biological systems. Since control theory concepts are not well known among biologists, I need a good standard ...
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1answer
385 views

How do I check the stability of a discrete transfer function?

I calculated the transfer function and let n = 1 , but how do I check the stability of the discrete time system when n = 1?
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1answer
92 views

How to get from theory to a working Industry Control System?

EE Student here who recently finished the classical control theory class. I was wondering the process of how the industry or anyone goes from drawing block diagrams to actually implementing in ...
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89 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 ...
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35 views

Transfer function using signal flow graph problem

Determine the system transfer function for the following signal-flow diagram of figure I have shown my attempt of solving this problem. Can anyone tell me whether I did this problem properly?
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28 views

Controller and compensator

What is the difference between controllers and compensators While searching for answer the most prominent answer I got was that compensator have magnitude=1 and is used to make sure the system ...
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1answer
58 views

How can I prove that for any control system root locus plot starts from poles of OLTF and ends at zeroes of OLTF?

simulate this circuit – Schematic created using CircuitLab G(s)H(s)=N/D T(s)=KN/(D+KN) Proof: ] But For K=0 T=0 For K=infinity T=infinity then how can K=0 {condition where forward path ...
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162 views

How to find Phase crossover frequency?

I make the imaginary part of \$loop \ gain=0\$ to find phase crossover frequency. But in one video, the person told that this method can only be applied when Polar plot crosses the real axis and ...
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50 views

Gain margin using Root locus plot

How can I find Gain margin of any control system given its polar plot In schaum's series I have read that Gain Margin=Ku/Ki but in given figure the system never becomes unstable so shouldn't Gain ...
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1answer
31 views

How do we determine the roots from a Routh-Hurwitz array?

I know that we can determine the roots on the right-half plane by counting the sign changes in the first column. However, I'm unsure how to find the roots on the left-half plane. Is it the same as the ...
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3answers
306 views

How does one position control a voice coil actuator?

I am looking at trying to position control a voice coil actuator (something like these). On the end of the voice coil actuator will be a small load (let's just imagine a 10 oz cube), screwed onto the ...
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1answer
90 views

Find the total gain from the following Signal Flow Graph

The signal flow graph for a system is given in the figure. Find resultant gain.
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32 views

Transfer Function For Electronic Pressure Regulator and a Step input

I was wondering if I could have some help in how to determine the transfer function for a Proportional Pressure Regulator. (VEAB-L-26-D7-Q4-V1-1R1). I have done a basic instrumentation and control ...
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1answer
32 views

Normalizing a nonlinear plant in system identification in control

I have calculated the "active power" and the "the reactive" power of a system in dq axis in nonlinear form and I am doing system identification on this "nonlinear" plant as a MIMO system. The problem ...
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30 views

Minimal State-Space-Realization using SVD

A similarity transformation with U produces so following state space model \begin{equation} (A, B, C, D) \stackrel{\tilde{x}=U^{\prime} \cdot x}{\longrightarrow}\left(U^{\prime} \cdot A \cdot U, U^{\...
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3answers
676 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 ...
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2answers
85 views

Stability and Positive/Negative feedback

I often read that positive feedback is used to get oscillators (since the output of the circuit is summed up to its input signal and so leads to instability), while negative feedback to get amplifiers ...
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45 views

Stability of Buck Converter when output capacitance is variable

I am designing a buck converter for an application that has several different loads. Depending on what devices are connected, the capacitance seen at the output of the buck converter can vary ...
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3answers
119 views

Why “-1 + 0j” is critical point on Nyquist plot?

I am reading about Nyquist plot from this (http://www.cds.caltech.edu/~murray/books/AM08/pdf/fbs-loopanal_11Nov18.pdf) chapter. On page no. 10-2 its mentioned that "-1 + 0j" is critical point on ...
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240 views

How can I control TRIAC firing angle automatically with a DC voltage?

I have to build an analog proportional controller for a 127 V, 1 kW AC heating resistance. The power delivered to the heating element must be proportional to the difference between a set point ...
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1answer
125 views

Buck-Boost converter without low side switch

Please look at the buck -boost converter below. It is 2 outputs, one buck and one boost output. Would the circuit work as describe in the picture? In what condition the circuit will it work? If so how ...
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0answers
24 views

Is it possible to predict the operating state of a power system (using MATLAB) if I have calculated the voltages at all nodes by state estimation?

If I have calculated all the node voltages by state estimation, is it possible to predict which operating state my system is at? By operating state, I mean any of the following: ...
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1answer
33 views

Characteristics from transfer function

All! I am trying to figure out characteristics of a second order system The system is (for example) And its characteristics for an unit step input are I want to solve this equation by hand and ...
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1answer
406 views

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 ...
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1answer
63 views

Steady error control system sinusoidal disturbance

Consider the control system closed-loop represented such a block diagram below: Given that: \$G_C(s) = K\$ and \$G(s) = 1/s\$ a) Determine the values of \$ K\$ which the closed-system loop is stable....
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2answers
141 views

Why am I getting non-sinusoidal output for sinusoidal input in a mass-spring system?

A mass-spring system is represented by the following transfer function $$ H(s) = \frac{s^{2} + 0.1s + 10}{s^{4} + 0.2s^{3} + 20s^{2}} $$ For a sinusoidal input I am getting a non-sinusoidal output, ...
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1answer
54 views

How do I refer the transfer function of a system from its Laplace equivalent?

I have a problem, I know how to analyze circuits in Laplace domain to get the transfer Laplace function. However, I don't know how to translate the answer to "real life" Suppose that I have a ...
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0answers
48 views

Controller for RC Filter

My class was asked to implement in MATLAB, a controller for an RC filter configuration with output response: 4/(s+3) The controller should give an output response whose steady state is 1 to unit ...
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1answer
248 views

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

Let say we have a DC-DC converter operates with double loop control (inner and outer) , and with switching frequency of Fs= 20000 Hz. Please ,if you could answer the two following questions: 1- ...
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1answer
364 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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1answer
144 views

PID (Arduino) Project - Determining Ki, Kp, Kd

I am working on control system project. I bought a Zumo 32U4. It has built in encoders. The project is divided into three parts: a) Move in a straight line. b) Slows down as obstacle approaches. c) ...
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2answers
293 views

Is the transfer function for the given RC network right?

For the question I arrived at the following answer (I have assumed V1 btw) Is my solution right? I just have a big doubt if whether I can use the voltage division rule at point A when there is an RC ...
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1answer
131 views

Relation between settling time and natural frequency for a critically damped system

In an article by Wie et al. (1989), for the purpose of calculating the gains of a controller, the equations of motion are approximated by the expression for a damped harmonic oscillation: $$\ddot{\...
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1answer
56 views

How to model a Electronic Proportional Control Valve

I am using a VSO LowPro Proportional control Valve (https://www.parker.com/Literature/Precision%20Fluidics/Miniature%20Proportional%20Valves/VSO%20LowPro.pdf) to regulate pressure into a closed ...
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1answer
53 views

System Identification in a closed-loop feedback system [closed]

I have an unstable system that doesn't have a useable output when open-loop excitation is applied. Subsequently I've used a controller to control its output. I want to use the system identification ...

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