Questions tagged [control-systems]

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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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2answers
436 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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1answer
106 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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1answer
32 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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1answer
45 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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1answer
45 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 bewtween the summation point and the plant to control? Is it allowed to do ...
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1answer
42 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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27 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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16 views

music sampler control

I'm a reasonably competent web programmer and I would like to know how I should go about learning to program a software that would control a music sampler. The hardware setup I was given is a sampler (...
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1answer
31 views

Region of root locus not inside the feasible region for a given performance specification

I wanted to plot the root locus for a system, whose plant transfer function is $$ P(s)= \frac{k}{Ts+1}e^{-ts}. $$ A PI controller was suggested for this system, and the task is to find $K_p$ and $K_i$...
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31 views

Kalman Filter: Difference between sensor input and control input

I recently saw a matlab sensor fusion example which combined IMU and GPS data for drone localization. What was surprising about it was that the IMU was used to predict future behavior of the system as ...
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1answer
35 views

Effects of delay in a discrete-time controller for a continuous-time plant

I'm trying to understand the effects of sample-to-update delay in digital control of power electronics. I am aware of the issue but not 100% sure how to quantify it. There is an interesting paper by ...
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1answer
39 views

How to approximate the transfer function of compensator using root locus?

I have the root locus of a system with and without compensator. The system is consist of a PD-controller and the process, the output is fed back to the controller via $G_s(s) = 1$. The upper graph is ...
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26 views

Signifance of statistical information in a signal

I am learning control engineering for some time and I work with a lot of transfer functions and frequency domain design. Reading from textbook, to me everything seems deterministic. Whenever I come ...
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23 views

Transfer function estimation using System identification

I am posting a control system problem here because of this post reference: https://meta.stackexchange.com/questions/207787/is-there-a-control-theory-site Question: I have input and output datasets. ...
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121 views

Time-Invariant (non)autonomous Systems

Regarding potential distinctions between autonomous, non-autonomous, time-invariant and time-varying systems, I have found out opinions supporting that: autonomous systems are time-invariant and non-...
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1answer
34 views

Extracting the DC component of a signal, that proportional to the displacement about the y-axis

I’m not sure that I clearly enough reflected the essence of a small problem in the title of the topic, but I’ll try to reveal its essence in the question itself. https://www.wolframalpha.com/input/......
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24 views

Control of a nonlinear static MIMO System

I am currently writing my master thesis and trying to design a controller for my system. However, the system is somewhat unconventional. It has a large number of inputs and outputs, is static, non-...
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26 views

Trajectory Planning and Optimal Control

When finding control inputs for ODE systems, gradient based solutions are often used. With the increase computational power will these solutions still be important over things like Monte-Carlo ...
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1answer
63 views

Why is the close looped model under control called plant?

I am not sure if the question even belongs here. Please correct me if it is out of context. Consider a closed feedback loop. Usually, we say that $K^L(s)$ is a controller over the plat $G(s)$. Is ...
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16 views

Feedforward disturbance signal compensation

The reference Feedforward control concepts through Interactive Tools says, to minimise the effect of the disturbance $d$ on the process output $y$, a compensator $G_{\text{ff}}=P_3/P_1$ shall be used. ...
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45 views

Finding the PID values for a vehicle control system

I'm trying to design a PID system for the longitudinal control of an autonomous vehicle. I figured out about most of it but I'm trying to figure out the Kp, Ki and Kd values. This is an illustration ...
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1answer
36 views

How to find the perfect regularization number?

I have an issue! Assume that we are going to solve $Ax=b$ but $x$ contains noise.To minimize that noise we can use regularization: $$x = (A^TA + \lambda I)^{-1}A^Tb$$ Where $\lambda$ is a small ...
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1answer
148 views

Fundamental questions about state-space and Kalman filters

I am a dsp guy, I only did a minimum of control theory back in university. While trying to grok state space analysis and (discrete time) regular Kalman filters, I am hitting a few questions that ...
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1answer
100 views

Model necessary for PID control

As I am not from control theory, I do not understand - after reading the Wiki page about PID control (https://en.wikipedia.org/wiki/PID_controller) and watching some videos - whether a model of the ...
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1answer
67 views

Stabilizing the inverse transform of a system

Currently I try to understand an unknown mechatronic system. I used white noise as an input signal and measured the output of the system. Then I estimated a 2nd order transfer function (Output/Input) ...
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1answer
29 views

why if I place the zero of the lead compensator at lower frequencies I have a resonance peak?

I am studying control systems, and I am studying the lead and lag compensator. I have seen than if I use a lead compensatpr in the following way: consider a closed loop transfer function: $T(s)=\...
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3answers
197 views

Whether $y(t) = x(t/3)$ is a memoryless system?

I am a newbie in signal and system, and feeling confused about the memoryless property, it says at the definition, if a system gives output only depends on present input, then its memoryless. So if at ...
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1answer
23 views

Measurement delay versus control delay

For a typical control loop (no delay, measurement transfer function is 1) the closed-loop transfer function is $$ H(s) = \frac{G_{comp}G_{process}}{1+G_{comp}G_{process}} $$ With an actuator delay ...
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1answer
61 views

What does it mean that a zero is slow?

I am studying control systems, and I have encountered the definizion of slow zero. I am searching on internet and on books, but I don't understand the meaning this. I know that if a zero is too slow, ...
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23 views

What is the difference between robust stability and robust performances for a MIMO system subject to uncertainty?

I am studying control systems and I am focusing on the case where uncertainty is present in the system. I have seen that in this case I have to be able to garantee robust stability and robust ...
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1answer
33 views

Does a RHP zero imposes some limitation in the time domain?

I am studying control systems and I have seen that a non-minimum phase zero imposes limitation in bandwidth , which is that the bandwidth has to be lower than a frequency which is half the frequency ...
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1answer
63 views

Problem in verifying zero blocking property of a zero of a multiple input multiple output system

I have a multiple input multiple output control system, and in particular a two inputs two outputs system. I want to find the zero state direction and the zero input direction of the system, which has ...
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1answer
47 views

Is it possible to use a control scheme with a delay as prefilter?

I am studying control systems, and in my studies I have encountered the topic of control scheme of the form and I have seen thaht this control scheme is really useful since it is possible to add a ...
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1answer
169 views

Can a pole at the origin be considered a dominant pole?

I am studying control syetems, and I have studied that the dominant poles of a system are the ones closer to the imaginary axis. Now, consider a system with a pole at the origin. Can this pole at the ...
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30 views

How do I design a reference filtering control scheme with a lead compensator?

I am trrying to design a lead compensator for a system. I have the following control scheme: where $Cr(s)$ is a prefilter which can be a lag or a lead compensator. My obkìjective is to design $Cr(s)$....
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17 views

Why does the step response has higher overshoot if the zero is too slow in a lead compensator used as a prefilter?

Consider a control scheme of the following type: where $C_r(s)$ is used to filter the reference, and it can be a lead compensator of a lag compensator. One thng I don't understand is why if I ...
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2answers
163 views

Why does the control effort increase if the bandwidth of the system is higher then the bandwidth of the plant?

I am studying control systems and I am focusing on the control effort. I have seen that if I place a pole at higher and higher frequencies, if the bandwidth of the system goes above the bandwidth of ...
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1answer
32 views

Multiply a measured quantity of a control-system in the frequency domain during continious operation

Currently I am working on a feed-forward control system to actively control vibrations. For that purpose I need to measure accelerations on a vibrating structure and use a transfer function in the ...
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22 views

Doubt on limitation of the bandwidth of the control sensitivity function

I am studying the mixed sensitivity design for control systems, and I have seen that by introducing weights, which can be for the senstitivity function, complementary senstivity function and the ...
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1answer
18 views

Understand diagram of a process

I've found this diagram in a slide, but i have no backround to properly understand it. Could you explain to me, in simple terms, how this process behaves and what's the purpose of the blocks $z^{-1}$ ?...
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29 views

How can we do exact simulation for digital systems? [closed]

In digital control system, there are two basic techniques for finding the best digital controller. First, called the discrete equivalent, we find the continuous compensation and then discretize (best ...
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2answers
51 views

Where does the error come from in PID control?

Let's say my thermostat is 50 degrees Fahrenheit. I know that 1000 units of kinetic energy are needed to raise the temperature from 80 degrees Fahrenheit. So I calculate how much I need to increase my ...
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1answer
66 views

Unstable plant transfer function identification

I would like to find the transfer function of an unknown unstable SISO plant. If it was a stable plant, I would input a sine sweep and measure the frequency response at the output; but I cannot do ...
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1answer
200 views

How do I find transfer functions from a state space representation?

Suppose I have a MIMO system in state space representation, for example: $A=\begin{bmatrix} 1 &2 &3 \\ 4&5 &6 \\ 7&8 &9 \end{bmatrix}$ $B=\begin{bmatrix} 2 &3 \\ ...
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0answers
64 views

Influence of a RHP zero/pole in the frequency response

I am studying loop shaping, and I am looking at loop shaping design with unstable poles and zeros. I have seen that noth unstable poles and zeros introduce limitations in the bandwidth. I have also ...
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1answer
40 views

Doubt on behaviour of frequency responce of a system

I am doing loop shaping using $H_{\infty }$ approch, and I have a plant with an unstable pole: G = 10/((s+10)*(s-1)); K1 = 4*(s+1)/s; where G is the plant, and ...
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1answer
54 views

Doubt on the relationship between the sensitivity and the complementary sensitivity function

I am doing loop shaping with the following transfer functions: G = 10/((s+10)*(s+1)); K1 = 0.5/s; where G is the process and K1 is the controller, and If I ...
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1answer
167 views

How can a stable system have a RHP pole?

I am working with a control system which has an unstable pole in the process. So I have the following transfer functions for the controller and for the process: ...
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1answer
58 views

What real object could be modeled by this transfer function? [closed]

What object from real world could be modeled by this transfer function? What could parameters b, p1 and p2 stand for?

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