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Questions tagged [control-systems]

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How do we determine the required sampling rate of a closed loop control system?

Consider the controlled dynamical system $\dot{x}_t = f(x_t, u(t-\tau_{sd}))$, where $0<\tau_{sd}$ denotes the time delay caused by sampling. It is intuitively clear that the time delay caused by ...
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A first-order system has a time constant of 20 s and input impulse of 20 units. What is the form of the differential equation for this system?

I am new to control systems Kindly help answering A first-order system has a time constant of 20 s and input impulse of 20 units. What is the form of the differential equation for this system? Should ...
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3 votes
1 answer
130 views

How do you design using bode plots?

[Control Systems Engineering by Nise] Hey, I have some confusion regarding bode plots and how they can be used to display both open loop and closed loop information. This also partially relates to my ...
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1 answer
36 views

Why is phase variable called like that?

I just read about phase variable-form here. ...
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3 votes
1 answer
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Designing a Transfer Function with given requirements

While reading about the root locus method, I thought of a question and couldn't seem to answer it. Suppose for a negative feedback system, all the open-loop poles and zeroes and the centroid $\big(\...
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0 answers
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Relationship between quantum non - causal order and control/feedback

Recently, in the field of quantum information, the causal structure of the events in a quantum mechanical system has been questioned. I'm thinking of the results in the following paper Quantum ...
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2 votes
0 answers
42 views

Non-rectangular meshgrid in MATLAB

I want to create a non-rectangular meshgrid in matlab. Basically I have a polygon shaped feasible set I need to make a grid of in order to interpolate 3D data points in this set. The function for ...
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0 votes
1 answer
46 views

How to design fir filter from transfer function

Transfer function is this equation in frequency domain: $$G(f) = \frac{1}{4\pi d} e^{i2 \pi d f/c}$$ or Hankel function d : constant (distance), c : 340 We may think we know complex number of ...
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2 votes
1 answer
86 views

Why the convolution of the impulse response doesn't match the system's output?

If you define an LTI system sys in scipy, you may conveniently feed an input x to it to get its output ...
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Step response of a given input and output (Laplace or Fourier)

I am trying to calculate the step response of the following given: Should I use Laplace transform or Fourier transform?
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4 votes
1 answer
177 views

How accurate is the dominant poles approximation in higher order control systems?

From what I have learnt from control systems classes, the dominant poles of a system are those that can be used to analyze a higher order system in terms of the formulas of a 2nd order system. I took ...
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How to find response of step function in matlab and plot transfer function?

I have an transfer function: $$\frac{Y(s)}{F(s)} = \frac{s^2+2s+3}{s^4+6s^3+13s^2+12s+9}$$ How can I find $Y(s)$ response of step function if $f(t)=\sin(5t)$ in MATLAB. And how can I plot the transfer ...
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49 views

Is it allowable to place a zero to cancel out a complex pole?

Consider the following transfer function : $$ T(s)=\frac{4}{s^{2}+2s+4} $$ I wish to design a lead-lag compensator satisfying a set of requirements. What matters for now is the process done to meet ...
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2 votes
1 answer
87 views

How to design a Controller that would adjust the steady-state error of a system?

I have a simple model (input-plant-output) with a transfer function : $$ T(s)=\frac{4}{s^{2}+2s+4} $$ The goal of this problem is to design a system such that it has the following specification for a ...
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0 answers
21 views

How can we translate this statement into an input signal expression?

I want to make sure if I got this right, the following statement: if the operator enters a unity sloped linearly increasing input then the output must eventually track the input and be at most 0.1 cm ...
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Poles and Zeros of a DiscreteTimeModelFunction with delay in Wolfram Mathematica

help me please, I have a problem with this TransferFunctionModel, When I want to obtain the poles from the Discrete Model Wolfram gives me an error, what am I doing wrong? Could it be the delay of the ...
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1 vote
2 answers
93 views

How can I use an irrational transfer function to convolve a signal?

I have the irrational transfer function $$H(s)=\mathrm{e}^{-a\sqrt{s}}$$ With the inverse Laplace transform $$ h(t) = \frac{a\,\mathrm{e^{-a^2/(4t)}}}{2\sqrt{\pi}~t^{3/2}} $$ For $a > 0$ How can I ...
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0 votes
0 answers
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Discretization of a controller

The desired control is $u_f=\frac{1+\eta s}{1+hs}a$, where $u_f$ is the feedforward control, $a$ is the feedforward observation and $\eta$ and $h$ are two constant parameters. However, I can only ...
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2 votes
1 answer
46 views

Designing a controller with hard output limits

I'm trying to put together a control algorithm to use a heater to drive a 2nd order thermal system to the target temperature as quickly as possible. I've done a nice state-space model with an extra ...
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1 vote
1 answer
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Stability concerns for closed-loop systems

I came across the statement Stability is a big problem in closed-loop systems, where a system may tend in some instances to overcorrect errors and cause oscillations. I wish to know some examples in ...
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  • 109
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1 answer
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Realize the given system in cascade form of 2nd order section in signal flow graph representation(with complex exponents)?

I know how to solve cascade form for normal case, but I don't know how to solve cascade form if I get complex exponentials. How do I solve this? Can you provide me 1 solved example or some hint or ...
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8 votes
1 answer
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Kalman Filter: How to Define Inputs and Outputs of a Model

I'm a software engineer with a CS degree working in machine learning. I'm trying to learn about Kalman Filters. In this short YouTube video from Mathworks, there's a discussion on a Kalman Filter with ...
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2 votes
0 answers
38 views

Are there control loops that attempt to maximize a process variable?

I'm working on Remote-Procedure Call (RPC) server that processes incoming streams of data from clients, and looking for a way to set a limit on the number of simultaneous streams allowed. There is ...
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1 vote
2 answers
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Matlab Pade approximation influence on bode plot and step response

I would like to approximate a delay via the pade approximation. I set a normal delay via the exponential term and I set a delay via the pade approximation and I look the difference between the both ...
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  • 145
1 vote
1 answer
41 views

Mixed - Discrete and Continuous system Laplace domain stability - Effect of Sampler and DAC

I have a system whose the plant transfer function is continuous and the compensation is discrete. I have an ADC which allows to measure the output of the system and a DAC which allows to control the ...
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3 votes
0 answers
68 views

real time - active noise control

I am trying to implement an adaptive filter for system identification and active noise control for realtime signal processing on an FPGA using Labview. For system identification, I implemented the ...
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4 votes
2 answers
361 views

How to set parameters of the PI controller inside the PLL?

I am going to implement in C++ software the synchronous frame phase locked loop (SFPLL) for estimation of angle and frequency of the three phase grid 220V/50Hz. For the internal PI controller setting ...
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1 vote
1 answer
306 views

Why is modern control theory in the time domain instead of the S-domain?

I am not sure if I am missing something, but from what I read I understand that modern control systems work in the time domain rather than the frequency frequency or S-domain. Wikipedia article ...
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2 votes
2 answers
40 views

cancellation controller transfer function design

This chapter offers a free overview on cancellation controllers. However, i did not get equation (6.4), how the transfer function of $G_R$ is determined?
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1 vote
0 answers
21 views

derivating input output relationship of a block diagram when there is noise added to the output

For the following system, I am not quite sure how the equation representing the input output relation is derived. Here, r is an input reference signal, $d_e$ is external disturbance and $n$ is noise. ...
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  • 141
2 votes
1 answer
114 views

Linear system stability criteria

Suppose we have a closed-loop system $H(s)=\frac{A(s)}{1+A(s)f(s)}=\frac{A(s)}{1+T(s)}$. I've seen the stability of the system stated a couple ways: If $H(s)$ has any poles in the RHP, then it is ...
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0 votes
2 answers
70 views

map float to fixed point

I have designed a system in simulink and works well through simulation. In order to convert to fixed point, I tried fixed point advisor with little success. The reason being that the coefficients on ...
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4 votes
1 answer
249 views

Developing Lead Compensator to Decrease Settle Time

This is a follow up to this question. I've approximated the transfer function for a system to be H = zpk([0.012 -1.05 18],[-0.22 -0.22 -45 -1000],10000);. My goal ...
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0 votes
2 answers
61 views

how to take a second order transfer function without any zeros and represent it using two first order transfer functions

does anybody know how to take a second order transfer function with no zeros (no s terms in the numerator): $$ g(s) = K\frac{\omega_n^2}{s^2 + 2\zeta \omega_n s + \omega_n^2} $$ and represent it using ...
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0 votes
1 answer
218 views

3D (time, scale, amplitude) plot in Continuous Wavelet Transform

I will be extremely grateful if someone could please answer this basic question. How can one plot a 3D (translation, scale, amplitude) plot from the Continuous wavelet transform (CWT) coefficients? ...
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1 vote
1 answer
105 views

What is the relation between eigenvalues and state-space response in control systems?

I understand the mathematics behind it but I want to know what happens physically in a real-life system. How do the eigenvalues come into the picture from a non-mathematical (physical) point of view? ...
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4 votes
2 answers
541 views

Which step response matches the system transfer function

A system has the following open loop bode plot: - Which one of the plots below describe the closed loop step response for the entire system? My attempt My initial thought was to look at the static ...
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4 votes
1 answer
533 views

How do I get a faster system response?

I have this model in simulink (the graph is my output): The step input has amplitude 0.5 m/s, and it steps up after 0.1 seconds. The gain $K_p=5$. The saturation block is to keep the voltage between -...
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0 votes
0 answers
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what is the difference between LMS and MPC?

I do understand that MPC is a control method and requires known model in the feedback path. LMS, on the other hand, is more like an adaptive filtering, which estimates the tap coefficients yielding ...
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2 votes
0 answers
38 views

State space representation using a given nilppotent matrix

I want to build a question on state space using a given, nilpotent matrix, $A$. $$q[n+1]=Aq[n]+Bx[n]$$ $$y[n]=Cq[n]+Dx[n]$$ Usually, I am using the canonical form so there is no problem extracting $A,...
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1 answer
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Part 2: Root Locus, Transfer Functions and Unit Step Response?

I'm continuing my question referenced here: Part 1 Question / Problem Description Say I have a new Root Locus shown below Consider the generic feedback loop, and the transfer function $G(s)$ shown by ...
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1 vote
1 answer
159 views

Root Locus, Transfer Functions and Unit Step Response?

Consider the generic feedback loop, and the transfer function $G(s)$ shown by the following root locus plot. Where $\mathbf{x}$ denotes the open-loop poles and $\square$ denotes the closed loop poles....
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0 answers
26 views

How to handle cross products in feedback loop?

I'm trying to simplify the following block diagram from to the following block diagram However, h(t), H(s) in time domain, has a cross product in it (gyroscopic torque). How can I represent the ...
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4 votes
2 answers
567 views

State space physical meaning

Let $T(s)$ be a transfer function that describes a mechanical system, where the input is force and the output is position. And let $[A,B,C,D]$ be the equivalent state-space representation of $T(s)$, ...
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  • 154
2 votes
1 answer
176 views

Ending points of the root locus

Let $$D(s) + KN(s) = 0 \tag{1}$$where $D(s)$ and $N(s)$ are polynomials of $s \in \mathbb{C}$ such that $\text{Deg}(D) = n, \ \text{Deg}(N) = m$ and $n\ge m$. The root locus method tells us how the ...
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0 votes
1 answer
233 views

What is the frequency of the Gaussian white noise model in control systems?

The design of control systems, particularly for SISO systems, is made convenient by tools such as Bode plots and the corresponding Nyquist stability criterion. These concepts allow engineers to design ...
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2 votes
1 answer
57 views

Why can't this system be adequately represented using a z-domain transfer function?

According to this question and answer the following system cannot be adequately captured by a z-transform transfer function. $$y[n] = y[n-1] + F_{\psi}(y[n-1)) + F_{\phi}(x[n-1])$$ where $F_{\alpha}(z)...
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  • 123
2 votes
1 answer
99 views

Controller in the feedback path?

What happens if the controller of a closed-loop system is placed in the feedback path before the summation point, instead of between the summation point and the plant to control? Are we allowed to do ...
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0 votes
1 answer
99 views

How does the intuitive notion of causality fit in with control systems?

Edit: By causality, in this question, I do not mean the traditional mathematical definition in the theory o signals and systems; I mean causality as in an intuitive 'what's moving/pushing what notion'....
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1 vote
0 answers
59 views

Are there any State Space Control C libraries?

I'm searching for a C library which implements methods needed for state space control (e.g. state feedback controller and state observer equations). Googling various terms only brought up a non-C (C# ?...
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