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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.

755 questions
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PID controller explanation

I haven't found a text that explains the PID controller in simple words. I know the theory: that it calculates the derivative and the proportional gain and the integral etc, but I need to know in reality what is the output of each function and each…
ergon
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How do I invert a system in state space form?

Suppose I have a system described in state-space form. Can I invert the system (swapping the roles of the input $u$ and output $y$)? If we start with: \begin{align} \dot{x} &= A\,x + B\,u \\ y &= C\,x + D\,u \end{align} and $D$ is invertible, then…
nibot
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Why is it called "Model predictive control"?

This will sound like a super silly question, but: Why is it called "Model Predictive Control"? I mean : the other types of control also compute the control input based on prediction of what is going to happen based on the "Model", no?
edamondo
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How to compare dynamic systems of different degree of abstraction?

I'm modelling a vehicle as a multibody system in Matlab/Simulink. My goals are: Have a realistic simulation model so I don't have to do prototype measurements all the time. Solve specific parameter estimation tasks and apply driver assistance…
Marius Oei
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Fuzzy control of anti-lock brake system

I was just reading about the anti-lock brake system example on the wiki page for fuzzy control system. The principle seems to be simple: instead of just assigning a SINGLE category (cold, cool, nominal, warm or hot) to the temperature of the brake,…
hooyeh
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4
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Negative feedback Gain and Phase Margin

Consider the system with unitary negative feedback such that the open loop transfer function is $$G(s) = \frac{as + 1}{s^2}$$ a) Determine the value of $a$ such that the phase margin is 45º b) Determine the stationary state error for the unitary…
Giiovanna
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understanding observers and estimators

I have seen several forums related to this question about the difference between observers and estimators in control theory and could not understand it clearly. I wanted to know how the state estimators and observers originated in first place. What…
gari
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Constructing a block diagram for amplitude control of an oscillator

I'm building a Wien Bridge oscillator. The oscillation part works just fine, but it currently limits on the supply rails. I want to add amplitude control, so I've added a precision rectifier which feeds an integrator that controls an LDR to change…
Remco Poelstra
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How do I compute/plot the open loop transfer function of a system given its state-space description?

Suppose I have a dynamical system with a continuous time state-space description given by the matrices A, B, C, and D, under full-state feedback u=Kx (where x is the state and x is the control input). How do I compute the Bode plot of the open-loop…
nibot
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Terminology for setting Set Points to avoid "Contact Bounce"-like characteristics

What is the terminology for having different/spaced-out on and off set points for a particular controlled process? When a system does not have the set points set appropriately, it could exhibit something like contact bounce. This is not limited to…
agent provocateur
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Finding the zeros for a PID controller

I would like to know what I am doing wrong for this PID controller design problem. I have all the parameters calculated ($\zeta$,$\omega_n$,$\sigma$...) and I have my target point set up. But now I need to find the zeros for the PID controller. I am…
Motorscooter
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How to compute the transfer function from a response graph

I understand that the model for a first order system is $$G(s)=\frac{k_m*e^{-\tau s}}{T_ms+1}$$ In this case $\tau=3$ and the system gain $k_m=10$, correct? I need to calculate the transfer function and after that I can calculate the poles by…
Rachel
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Discrete Control System Process Sampling Rate

In digital or discrete control, instead of continuous analog-type variables, a controller samples a process variable signal at regular discrete time intervals. So, effectively, the process variable does not change as far as the system is concerned…
Mephistopheles
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Condition for system stability

Why does positive phase and gain margins cause any system to be stable whereas negative phase and gain margins cause the system to be unstable ?
TVV
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Determining Gain from a root locus plot

I was looking over practice problems for an upcoming exam and I am struggling with root locus. I understand how to plot the basic root locus but for some of the aspects when gain is asked to be calculated for plots I'm stumped. I was wondering if…
Motorscooter
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