Questions tagged [control-engineering]

Questions about the models and theories of control engineering and the application of control theory to design systems with desired behaviors.

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1answer
79 views

Can someone explain how the output of this control system is derived?

I understand equation (1), but I really don't see the connection between equation (2) and the picture. For starters, shouldn't the $b_0$ constant be multiplied by $$net(n)-(a_1 \cdot net(n - 1) + a_2 \...
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2answers
335 views

Definition of a 'manipulated variable' in process control - what is a manipulated variable exactly?

I've gathered a lot of different details online - trying to understand exactly what they mean by 'manipulated variable'. So I only decided to finally ask about it here. In one source - eg. at this ...
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1answer
40 views

How to decrease Nitrogen gas consumption in Iron & Steel Plant? [closed]

I need to decrease nitrogen gas consumption in iron & steel plant. Currently it's not possible to measure every dot from steel mill to determine real usage so they use what air separation unit ...
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1answer
76 views

Adapting PID controller parameters using expert rules

I use the following equation to calculate a control signal of a time-discrete PID controller: $$ u(k) = u(k-1) + K_{R} \cdot \left(1+ \frac{T_{0}}{2 \cdot T_{I} }+ \frac{T_{D}}{T_{0}}\right) \cdot e(k)...
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1answer
119 views

Gain and Phase Margins from Bode Plot

What's the interpretation of the margins when the curve of magnitude never crosses 0 dB or the phase curve never crosses the -180º? For example: $$G(s) = \frac{s+20}{(s+1)(s+7)(s+50)}$$ I know that ...
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1answer
388 views

Nyquist Stability Theorem and Clockwise/Counter Clockwise Encirclements

According to argument principle, if a contour encircles a number of poles and zeros of a transfer function, the number of origin encirclements can be deduced by : ...
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2answers
145 views

A clarifying question on Lasalle invariance principle

Given a nonlinear system \begin{equation} \dot{x}=f(x),~x(0)=x_0 \tag{1} \end{equation} where $f\in{\mathcal{C}^{1}}:D\to\mathbb{R}^{n}$. The Lasalle invariance theorem statement goes as follows: Let $...
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0answers
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Monitoring Connectivity on ZigBee

I am trying to figure out some ways in which a ZigBee network can be monitored. As is the case in any network, here we have a central coordinator and several slaves joined, however, there seems to be ...
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2answers
337 views

controllability matrix of a state space system - determinant

For state space systems, there is a test for 'controllability' involving finding the determinant of a 'controllability' matrix. The instructions for the test is typically to see if the determinant is ...
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0answers
46 views

Why does my motor model match the actual data in transient but not steady state response?

I have created a model of a DC Servo motor using electromechanical system modeling. I simulated the motor in Simulink (MATLAB) and compared the data with data obtained from a real motor having similar ...
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1answer
106 views

Limitations of LTI systems & control

I'm trying to think of limitations or disadvantages of LTI systems in control theory, however, I can't think of many. The only one I can think of is that not every system is an LTI system. Linear time-...
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1answer
94 views

designing compensator with certain specification

Ηere is an open-loop transfer function and specifications for compensator design. I defined the required poles and defined the angles according to the normal procedure of the root locus method and ...
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3answers
132 views

Bandwidth vs Capacity

Two questions on wireless transmission, packed into one. First: I am confused about the meaning of the term 'Bandwidth' in a wireless transmission environment. The two most common definitions I could ...
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1answer
77 views

Zeroing a ventilator's volume measurement in the face of drifty sensors

I'm a software engineer working with http://respira.works to build an open-source ventilator for COVID-19. Notably, I'm not a controls person or a hardware person, so please forgive me. Background ...
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1answer
47 views

Why is there a delta for locally stable in the sense of lyapunov?

Why does this definition (screenshotted above) for locally stable i.s.L. require a $\delta$ term? Why not just say, something is locally stable i.s.L. if "for any ball of size $\epsilon$ around the ...
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3answers
225 views

What are these rotary to linear movements called?

I’d like to know what the below movement mechanisms are called so I can better research them and incorporate them into my own designs. They are both quite similar, they are from rotary electrical ...
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2answers
69 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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2answers
91 views

What is the easiest way to regulate the speed of a falling object?

I want to design a system that allows a 1kg metal brick to fall under gravity at variable speeds. The brick initial position is 20cm above a flat table. I want to have control on the duration (to ...
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1answer
123 views

Help understanding a control system represented by coefficients of theta?

I've been working with control systems and transfer functions recently, but I've come across a format that I haven't seen before using coefficients of theta, and I can't find any information about it. ...
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23 views

Optimal Control Singular Arcs

This is about linear time-invariant, stationary problems. According to Donald Kirk's book Optimal Control Theory, for minimum-fuel problems on page 299, I was told that if there exists a singular arc,...
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37 views

Skew-Symmetric Gain Matrix to Encourage Exploration

I am reading a paper on controls and it has the following snippet: We propose to use the control law $$u_i = K(CV_i − p_i)$$ , where K is a (potentially time-varying) uniformly positive definite ...
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1answer
43 views

What is Dissipitative Control?

I am reading an article that says: stabilize the multi-vehicle system to one of its local minima via dissipative control And other that deals with dissipative system: (PID) controllers is ...
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1answer
296 views

How to find the transfer function of a control system?

I have a linear control system defined by the following equations: \begin{array}{l}\dot{x}_{1}(t)=-\frac{1}{2}\left(x_{1}(t)-x_{2}(t)\right) \\ \dot{x}_{2}(t)=\frac{1}{10}\left(2 x_{2}(t)-10 x_{1}(t)\...
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0answers
68 views

Converting nonlinear system into equivalent nonlinear of the Byrnes-Isidori normal form

I have a nonlinear system (Ball & Beam) which is described by the following equations of motion: $$ \ddot{y} + \frac{mg}{a} \sin(θ) -\frac{m}{a}y\dot{θ}^2 = 0 $$ $$ \ddot{θ} + \frac{2m}{b}y\dot{...
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51 views

Lyapunon candidate function to derive parameters estimation law

I have a system and a reference model represented in state space in the following form: \begin{gather} \dot{x} = Ax+Bu \\\ u = \hat{K}(t)x+\hat{k}_r(t)r \\\ \\ A_m = A+BK \\\ Bk_r = B_m \\\ K,k_r : \...
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1answer
81 views

Input-output representation to state space

How do you create a state space representation of the following input/output equation: $$ \dot{y} = -ky + u + a\sin(ωt) $$ where the parameters $k$, $a$, and $ω$ are unknown. The end goal is to ...
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35 views

maintenance of steady flow through pressure or mass flow

let's say I have two points in a line, A and B. Between them there is a valve that can regulate the amount of the stream from A to B. Considering that there is a steady flow of the stream between A ...
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1answer
249 views

Root Locus and Routh–Hurwitz stability criterion

A satellite launcher has a unit feedback system, whose TF global open loop is given by: $$G_c(s)G(s) = \frac{K(s^2-4s+18)(s+2)}{(s^2-2)(s+12)} $$ a) Draw the root locus for this function b) ...
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1answer
81 views

Generating Linear Velocity Movement?

In preparation for a Fluid Mechanics experiment, I am looking for a simple commercial ready made apparatus to generate a linear velocity trend to prove a new theory: https://aip.scitation.org/doi/abs/...
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3answers
853 views

Determine the gain K from a root locus

I'm studying Root Locus method and I still confused. The question below exemplifiques my doubt. Determine the $K$ gain so that the dominant roots have a damping factor equal to $0.5$, where $$G(s) =...
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1answer
139 views

Physical interpretation of a Bode plot

I have a few questions regarding the physical interpretation of the information presented on a Bode plot. I believe it is one of those cases where I "don't know what I don't know", so please bear with ...
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1answer
42 views

Where can i get the aerodynamic data of aircrafts for controller design and testing?

I have some research papers on aircraft controller design that i want to simulate, but no system data is given in the research paper itself. I am also unable to find the aerodynamic data for any ...
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0answers
47 views

Mathematical transformation of a heading angle to a roll angle

I'm trying to understand a function in a SIMULINK example of a path following UAV simulation. The gist is that, the UAV Waypoint Follower block provides a required heading from a list of waypoints and ...
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1answer
105 views

Passivity in State Space Systems

Suppose I have the state space system $a\dot{x} = -x + \frac{1}{k}h(x) + u$, and output $y = h(x)$, where $a,k > 0$. The only information I'm given about $h(x)$ is that $h\in[0,k]$. I want to show ...
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1answer
40 views

Bounds to prove exponential stablity for given Lyapunov function

Problem 3.6 in Khalil's Nonlinear Control: Use given Lypunov candidate function to prove that the origin is exponentially stable. The system is $$\dot{x}=\begin{bmatrix}x_2\\-h(x_1)-2x_2\end{bmatrix},...
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37 views

avoidance with LQR

I'm interested in using linear quadratic regulators (LQR) to model prey avoidance behaviors. I want to adapt the LQR algorithm to incorporate dynamics and state costs that maximize the distance from a ...
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1answer
60 views

Modeling the torque of a real motor

I am trying to control a real inverted pendulum by means of a DC motor, for this I must model the torque of the motor, the work I've done in this direction is the following (which I believe is right): ...
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1answer
101 views

How to obtain transfer function of control diagram with Internal Model Control?

I want to design a robust control system using the internal model design specifications. The block diagram is the one shown below: I am trying to obtain the transfer function $\ \frac{Y(s)}{R(s)} $ ...
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1answer
36 views

Evaluate "damping" of higher-order transfer function - something similar to settling time without the discontinuities

I have an 11th order transfer function in the continuous domain (simplified linearized model of a grid-forming converter) and I'm looking for a way to characterize it with a single number for ...
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1answer
320 views

Find the transfer function of a basic block diagram

I'm new to Control Systems. I've been given this block diagram and I would like to find the overall transfer function. How can I do it? I was thinking about simplifying the diagram by placing in ...
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0answers
80 views

How many kWh this turbine would generate?

My grandfather and I are running some experiments down the river, however we don't have expertise in engineering so I bring up this question to the community and hope someone could help. How many kWh ...
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1answer
36 views

Noise sensitivity transfer function

Consider we have a second order system (plant) described by the following transfer function: $$ P(s) = \frac{b_0}{s^2+a_1*s+a_2} $$ which is controller by a PD-controller: $$ C(s) = K_p+K_ds $$ ...
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1answer
49 views

Compare Genetic Algorithms and Markov Chain Monte Carlo in their statistical properties in parameter estimation task

I am using GA and MCMC for estimating the parameters of a transfer function. GA returns results that each parameter has one value when minimizing the error function, and MCMC returns the whole chain ...
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1answer
185 views

How to reduce oscillations (rapid changes of control signal) when controlling a real system, which occur due to noise in measurement from sensors?

I have a real mechanical system (ball & beam) which I want to control. The system is approximated by the second order transfer function: $$ T(s) = \frac{b_0}{s^2+a_1s+a_2} $$ and in state-space ...
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1answer
259 views

How to find closed loop transfer function and use it to identify τ and k?

I have to answer a few questions on transfer functions using Matlab. The first question, which I solved without Matlab, gives a time response graph for an LR circuit, and asks me to find the first ...
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1answer
240 views

Proportional-Derivative compensator design

I have been struggling with the following problem for a few days now and would greatly appreciate some assistance. I'm new to control systems and have very little experience with PD controllers and ...
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2answers
283 views

Increasing Kd in PID control loop

Why does increasing derivative gain $K_d$ in a PID controller loop lead to a reduction in overshoot and an increase in rise time? This is not a homework question, it is a question to improve my ...
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1answer
121 views

Does this PID-like algorithm make any sense for a solar inverter?

The application I want to implement the control of a photovoltaic inverter. The goal would be to keep the consumption of a microgrid (the power absorbed from the grid) to a constant value. Notes: I ...
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1answer
174 views

Control System; Finding resonant frequency of 3rd order

We've been requested to find the resonant frequencies of a 3rd order plant in class and were presented to the following method to do so: My question is, when using the $\ \omega_r $ formula, to find ...
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0answers
51 views

Kalman Filter by Orthogonal Projection

I'm working through the derivation for the Kalman filter using orthogonal projections. It's pretty intuitive that if we want to generate the best linear estimate for an $n$-vector $x$ using some $m$-...

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