# Tagged Questions

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31 views

### Problems calculating Z-transform

I am trying to solve a class exercise in which I am given the following, in Laplace domain: $$G(s)=\dfrac{e^{-Ts}}{s+3}$$ $$H(s)=\dfrac{1}{s}$$ And I need to calculate $\dfrac{C(z)}{R(z)}$, which is ...
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### Designing a root-locus compensator to attain design requirements

I am working with Matlab to design a compensator capable to make a system attain the design requirements ($\omega_n\geq 0.3$ rad/s & $\xi\geq 0.5$). In order to do so I have a discrete-time ...
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### What is the Reference in Control Theory?

I've started studying Control and I've come across some concepts that I'm finding a bit difficult to understand. For example, in the system showed here, there is a signal called "reference" as well ...
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### Can bandwidth of the closed loop be bigger than bandwidth of individual elements in it?

This is a question from control theory but I hope you can help me with it. I was pointed to this community. So in my control loop I have elements that have cut-off frequency of 3-5kHz and I designed ...
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### Showing a system is always controllable?

I need to show that the following system is always controllable: \begin{align}A &= \begin{bmatrix} -\alpha_1I_{k\times k}& -\alpha_2I_{k\times k}& \cdots &-\alpha_{n-1}I_{k\times ...
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### Controlling the pursuit path of the human eye?

The human eye scans images by panning focus along a certain path. I've read that eye tracking studies have revealed that there is a feedback process involved in moving ocular focus along a path that ...
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612 views

### Why is an RC circuit a first order system?

I am going through the following tutorial: Time-Response Identification of a Resistor–Capacitor (RC) Circuit Why do we call the RC circuit a first order system? I understand the order of a system ...
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### Why is it necessary to have two state variables

I am learning about control theory. Let's consider this system. $$m a(t) + b v(t) + k x(t) = f(t)$$ $a$ is acceleration $v$ is velocity $x$ is displacement $f$ is external force In my ...
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### Benefits of oversampling in a realtime noise-cancellation system

When sampling a signal, it is standard practice to use a sampling rate that is greater than two times the bandwidth of the signal in order to avoid aliasing. The result is then low-pass filtered (and ...
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### phase locked loop

I have seen that to get the phase angle of a signal, we have to use PLLs. this PLL is modeling in order to get the phase angle about one frequency, which is the free running frequency of the VCO. If ...
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### Frequency response of a (rectangular) integrator

A very simple question which can't really figure out: I have a simple discrete time rectangular integrator with Z transform H(z) = 1/(1-Z^(-1)) Plotting the frequency response with Matlab using ...
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### Troubleshooting PID controller

I'm developing a PID controller to control the position of a laser beam. The position is measured using a Position Sensitive Device (PSD). I modeled the plant according to the manufacturer specs and ...
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### What is pulse train filter?

I have recently seen some code written in modelling tool like Simulink, ASCET which uses PT1 filter? Why do we use a pulse train filter? What is the difference between FIR, IIR, Chebyschev, ...
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### Improving velocity estimation

I have a sensor reduction model which gives me a velocity estimate of a suspension system(velocity 1) . This suspension system estimate velocity is used to calculate another velocity(velocity 2) via ...
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### Why eigen values and poles of a system are equivalent?

In control systems engineering, the stability of a system (modeled in the form of Transfer Function) is determined by the poles of the system in the right or left hand sides. When the model is ...
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### PID Control - process variable / setpoint

I'm trying to design a PID controller but I have a problem in the following case: The process variable can only be between 0 and 1. The setpoint can be close to one, for instance 0.97. Hence the ...
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### Why does the impulse response determine the transfer function of a system? [closed]

why does it describe the transfer function.. How come? Especially for LTI systems. I thinking about the theory about how come an impulse input can provide information about a complete system.. As it ...
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### How to form Kalman filtering matrices for a problem with variable acceleration?

Assuming we have time vector $T$ with constant time step $dt$ position vector $X$ velocity vector $V$ acceleration vector $A$ All vectors $X, V, A$ have noise on their measurement ( $n_x$ , $n_v$ ...
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### System indentification different inputs

I have peformed different form for input/output relation to determine a system, but seem to be missing some theory which input will be the most will excite enough modes such that the models which i ...
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### Perfect system identification or am i doing something wrong?

I am using MATLAB to identify a system. The problem with my method is that my result is perfect. I get a nearly 100% fit, which make me wonder if what I am doing is correct. I feed a sine sweep with ...
137 views

### What is the low-pass filter that gives minimal transient response?

As title says, what is the low-pass filter that gives minimal transient response? By minimal transient response, I mean minimal settling time with reference to very tiny amount of divergence of ...
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### Inputs for system identification

What effects does have a different input such as impulse, step, sine sweep etc. on performing a system identification? I mean what is up/down side, and which one is best, and why chose one rather ...
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### Discrete dataset into to continous dataset?

I am trying to perform system identification on a system.The input i am going to provide is sinewaves with different frequencies. I sampled a sine wave with 100 Hz which is used a input for the ...
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### What kind of filter is this?

Is this filter a BPF? $$\dfrac{z}{z-a}$$ where $a$ is some complex number? If we put a pole somewhere on the unit circle it will emphasise a certain frequency, is that right?
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### Given the digital filter, how does one minimize transient reponse while keeping steady-state resposne?

Suppose the digital filter is given by $H(z)$. If the input is $0$ for $n<0$, then when input occurs at $n =0$, transient response will necessarily be there. So I want to minimize this transient ...
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### input output read/write frequency

I am trying to identify a system based on input/output response and thereby estimate a transfer function. I generated a frequency sweep function in Mathematica which gives me the discrete values of a ...
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### Do FIR filter have any application in control theory?

I know about IIR filter as discrete pendent to transfer functions in the Laplace domain. So it is actually quite simple to convert the function of the control system and finally receive the discrete ...
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### Root Locus for a system

I know this subject tends more to control theory but I am certain its part of the global knowledge basis for engineers, thus I believe I can find the answer here. I'm trying to draw Root Locus for ...
119 views

### What is the physical interpretation of the dB scale on a bode plot and what is a negative dB?

I have no physical interpretation of the Bode plot. What does it mean for a bode plot to have negative dB over its entire duration on the log-scale frequency?
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### What is the difference between a sampled time system and a discrete time system?

I am trying to evaluate whether I should control a system in simulink using sampled data system or discrete time system. The discrete model is as follows: The sampled time system is as follows ...
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### Why is my bode plot showing periodic behavior?

I found something very interersting when I was trying to simulate a discrete time system. So first I discretized the continuous system $G(s)$ using "c2d" function and "dbode". The resulting bode ...
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### Stability of an unstable system using nonlinear element. Is it possible or not?

Say there is a system with open-loop transfer function G(s)=1/(s−1) . The system is definitely unstable. If I put any nonlinear system in cascade with G(s) and from the output, a negative unity ...
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### How to intuitively understand the state space formulation of discrete time system?

The SS formulation of DT system is given by $$x[(k+1)T] = Ax(kT) + Bu(kT)$$ $$y(kT) = Cx(kT) + Du(kT)$$ Note: T is the sampling period and often omited Can someone explain to me why the state ...
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### For a standard second order transfer function, what is the equivalent time domain significance of $\zeta>0.707$?

In frequency domain $\zeta>0.707$ implies no resonant peak in frequency response. But I am unable to correlate what is the exact time domain effect of this? If $\zeta=0.707$ acts like an ...
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### Does the system matrix being singular tell us anything about the system?

If we have a linear system, represented in State Space and the A matrix is singular (det(A) == 0), can we expect any special properties from the system?
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### Iterative Kalman filters and system parameters estimation

i am working recently on a project in which i want to implement a Kalman filter as being an observer, and i couple this observer with a state feedback controller that produces control actions ...
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### How to periodically estimate states of a LTI if the output is measured irregularly?

How can I periodically estimate the states of a discrete linear time-invariant system in the form $$\dot{\vec{x}}=\textbf{A}\vec{x}+\textbf{B}\vec{u}$$ \vec{y}=\textbf{C}\vec{x}+\textbf{D}\vec{u} ...
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### Wavelet transform in control systems

In control systems, the Laplace transform is often used to analyze the stability and the performance of LTI system. For instance, the LTI system is stable if and only if the transfer function, which ...
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### Describing Function for non-symmetric Saturation Model

Let's talk about a standard saturation model: with bounds $bound_{lower}$ and $bound_{upper}$. So in this example the output $y$ will be: y(u) = \begin{cases} ...
There are two real signals in the form of $A_i sin(wt+p_i), i=1,2$. Suppose frequency $w$ of both the signals is the same and amplitude $A_i$ and phase $p_i$ are different. The first signal has ...