Questions tagged [control-systems]
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274
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Why a differentiator is unstable from pole zeros view point?
A differentiator with frequency response $j2 \pi f$ is unstable because as frequency increases its response becomes out of bound.
But from a pole zero point of view a differentiator just have zeros ...
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How do I reduce a block diagram with just a line as a feedback loop, I dont get how it adds K to the denominator
How do I reduce a block diagram with just a line as a feedback loop, I dont get how it adds K to the denominator.
The bottom equation is supposed to be the answer.
2
votes
1
answer
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Transfer Function Estimate
This is related to this post: https://engineering.stackexchange.com/questions/56050/obtaining-the-open-loop-gain-estiamte-the-gain-and-phase-frequency-response
Using python, I would like to write a ...
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Difference between H2 control and input shaping
Let us assume a system with external disturbance to reject. The system that is used for controlling has vibrations, that we would like to avoid.
We assume moreover that the dynamics are known (10% ...
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43
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Direct and numerically robust conversion from zero-pole to state-space representation
Note: this question was initially asked in a different community.
Encouraged by the comments, I decided to cross-post here too.
Given (z,p,k) my goal is to convert to a state-space representation (A, ...
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Finding the region of stability of a system
Suppose we have a closed loop system controlled by some microcontroller $K$
First we take the open loop gain which is $\frac{K}{s(s+6)}$.It has 1 pole at the origin and at $s=6$ and 0 zeros.
So we ...
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36
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Converting simulink PID block to C code
I have implemented and tuned a PID block in a simulink model and now i want to convert this block to C code to use on my micro controller I have taken the discrete equation of the PID block and the ...
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Max input of a system given it's transfer function and an assumed step change (beginner)
I have an exercise that gives me the following transfer function
$$
\frac{0.5}{s+0.5}
$$
and an assumed step change in the target of 20
I am asked to calculate the maximum input for the assumed step ...
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46
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What equations do I need to find the requested parameters?
Consider a filter of the form $$ 𝐹_{posic}(𝑠) = \alpha_1+\alpha_2e^{-sh}.$$
Find the parameters $\alpha_1, \alpha_2 \in \mathbb R$, and $h > 0$ such that
$P_{\theta\phi}F_{posic}$ is an FIR (...
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Controllability matrix is full rank identity matrix
What does it mean, when my system has controllability matrix that is full rank and identity matrix? Having full rank means that the system is controllable, but does the Identity feature of my ...
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How to implement FLL / carrier recovery? Code and math included
There are lots of options in textbooks, youtube and website blogs.
There seems to be three options:
Calculate phase difference between samples to infer frequency error or offset.
Calculate phase ...
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How to determine if a system is minimum phase or not?
I'm studying for an exam and this is an old exam question that I don't understand:
Is the following system non-minimum phase?
$$G(s) = \frac{e^{-2s}}{s+2}$$
I can see that the real part of the pole is ...
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44
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Implementing digital controller in the time domain
I have simulated a digital control system in the Z domain using MATLAB and I have got satisfactory results. However, when I converted the plant and the digital controller to difference equations and ...
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Python package to manipulate linear systems
I'm doing some control system work. I was shocked* -- shocked to learn that while Scipy has some nice linear systems classes, they don't extend to computing the cascades or paralleling of two systems....
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How to discretize the continuous time domain state space model?
I have a dsp algorithm which is based on the below given state space model in the continuous-time domain
$$
\begin{bmatrix}
\frac{\mathrm{d}\hat{\psi}_{r_{\alpha}}}{\mathrm{d}t} \\
\frac{\mathrm{d}\...
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How does the state estimate selection work?
I have been solving following problem. I have two open loop state estimators used for estimation of the unmeasurable states of a given linear dynamic system. The first estimator provides estimate $\...
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Why does a root locus show that system is stable but unit step response of a system does not have a stable output?
From what I know about root locus is that if all roots are located on the Left Half of the S-plane the system is stable. That's why I expected the unit step response of a system to be stable.
...
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Digital PID controller implementation
I am not sure whether I have chosen correct forum for my question. The question regards the implementation of a digital PID controller. From my point of view it is a kind of digital filter which is a ...
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What is the point of using this derived PID controller?
Previously, I answer for this PID controller that I want to understand completly.
This is used for control the opening $U_n$ of a valve let gas pass and reach a certain pressure (SetPoint).
There is ...
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63
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Conceptual doubt about PID algorithm in PLC
I have to use the PID algorithm that I describe below, obtained from a PLC in the company where I work, so I want to understand it. This is used for control a valve that opens to let gas pass and ...
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LMS Adaptive Filter for system identification
i am currently attempting system identification using the LMS algorithm. The input and the output data are available and are very noisy and consists of multiple frequencies. The input and the output ...
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143
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Tuning Active Power Factor Correction converter works in Simulink, but having trouble achieving the same in DPS
I am trying to tune the Active PF Correction converter current and voltage loop to get a sinusoidal input current. I can get to a voltage reference, but the current looks like this. Reading the ...
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Multirate Control System Transfer Functions
I'm interested in oversampling the inputs to a digital controller to increase the SNR of the input process variable signal. I've read on this site and in articles like the one below that it is not ...
- 266
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Different PI controller implementations and their respective discrete transfer functions
So I need to implement a PI-controller and I found an Implementation of an PID-controller with some background explanation. I adapted the implementation to an PI-controller, implemented it and got the ...
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119
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What is causal inverse of a system?
Let's say that I have a system $H(z)$. What is causal inverse and how do I compute the causal inverse of $H(z)$?
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Regulating a reservoir for smooth output flow while avoiding under/overflow
Say that you have a reservoir of fixed capacity, $V_{max} [m^3]$ and some level of fill $V [m^3]$.
Liquid is flowing in a stochastic, but observable rate:
$$x(t) [m^3\cdot s^{-1}]$$
You are given a ...
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Intuition for $\mathbf{P} = \mathbf{0}$ in steady-state when $\mathbf{Q} = \mathbf{0}$ (Kalman filter)
Consider the following discrete-time system:
\begin{equation}
\mathbf{x}(k+1) =
\mathbf{A}_d
\mathbf{x}(k)
+
\mathbf{B}_d
\mathbf{u}(k)
\end{equation}
\begin{equation}
y(k) =
\mathbf{C}_d
\mathbf{x}(k)...
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Confused with special cases of Routh-Hurwitz
When the first column only has a zero we replace is with an $\epsilon$ so we don't divide by zero ahead but divide by the $\epsilon$ then take the limit as it goes to zero.
meanwhile if an entire row ...
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Is there a standardize method for writing statements combinations of (RF) signal flow path through a system?
Let's say I am given a system block diagram of various components that either route/switch/amplify/filter and so on. Each of these components of the system perform these signal modifications or lack ...
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884
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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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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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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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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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270
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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}$$
or Hankel function
d : constant (distance),
c : 340
We may think we know complex number of ...
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Why doesn't the convolution of the impulse response match the system's output?
If you define an LTI system sys in scipy, you may conveniently feed an input x to it to get ...
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Step response of a given input and output (Laplace or Fourier)
I am trying to calculate the step response of the following given:
Should I use Laplace transform or Fourier transform?
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1
answer
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How accurate is the dominant poles approximation in higher order control systems?
From what I have learnt from control systems classes, the dominant poles of a system are those that can be used to analyze a higher order system in terms of the formulas of a 2nd order system. I took ...
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How to find response of step function in matlab and plot transfer function?
I have an transfer function:
$$\frac{Y(s)}{F(s)} = \frac{s^2+2s+3}{s^4+6s^3+13s^2+12s+9}$$
How can I find $Y(s)$ response of step function if $f(t)=\sin(5t)$ in MATLAB. And how can I plot the transfer ...
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Is it allowable to place a zero to cancel out a complex pole?
Consider the following transfer function :
$$
T(s)=\frac{4}{s^{2}+2s+4}
$$
I wish to design a lead-lag compensator satisfying a set of requirements. What matters for now is the process done to meet ...
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348
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How to design a Controller that would adjust the steady-state error of a system?
I have a simple model (input-plant-output) with a transfer function :
$$
T(s)=\frac{4}{s^{2}+2s+4}
$$
The goal of this problem is to design a system such that it has the following specification for a ...
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How can we translate this statement into an input signal expression?
I want to make sure if I got this right, the following statement:
if the operator
enters a unity sloped linearly increasing input then the output must eventually track the
input and be at most 0.1 cm ...
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How can I use an irrational transfer function to convolve a signal?
I have the irrational transfer function
$$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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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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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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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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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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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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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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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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