# Tag Info

Accepted

### Block diagram vs flow chart?

Use Google's define:<item to look up> feature. block diagram noun: block diagram; plural noun: block diagrams a diagram showing in schematic form the ...
• 10.9k
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### Is nonlinear control slower than linear control?

"Linear" imposes a set of restrictions. "Non-linear" simply means there are no restrictions. Many non-linear control schemes can be faster than linear ones. Linear control schemes are restricted to ...
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• 1,069
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### How do I interpret the following Bode, Nyquist and Nichols diagrams?

Your systems shows extremely close pole-zero cancellation. So much even that it nearly removes 4 poles and zeros. Lets look at why, starting with the Bode plot: The magnitude plot is constantly ...
• 1,069

### Full state feedback of a closed loop system

Let me phrase this a bit more elaborate. Suppose we have a state space system, ie: $$\dot{x} = Ax + Bu$$ Where the dynamics of the system are presented through $A$. For instance, the poles of the ...
• 1,069
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### Control theory - Differential equations and state variable description

A professor of mine, long ago, once quipped: "Give me a word... any word at all... and I'll show you how the root of that word is a PDE!" A touch of Philosophy All physical systems are modeled ...
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### Difference between PI and PD controller?

PI - Proportional - Integral The output is a combination of how far you are from the goal and the integral of your distance from the goal (total error over time). This means that it will track small ...
• 766
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### What do actually control engineers do?

In short, 'systems' refers to a combination of components that act together and perform a certain objective. A system can span across different physical and virtual domains. Controls engineers ...
• 56

### Anomaly in viscous force - vs - velocity relationships

The examples you mentioned both occur due to turbulent flow of a gas. However in a lot of mechanical systems damping often occurs due visco-elastic deformation or due to shearing of the lubricant ...
• 1,653

### How to determine the region in a state plane where the equilibrium state is asymptotically stable

As you might already know your system is nonlinear, which means that it is not trivial at all. See below for the plot of the system. The linearization around $(0,0)$ gives you the information that the ...
• 1,036
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### Nyquist plot - what is the meaning of circles with dB values on complex plane

See doc nyquist: The nyquist function has support for M-circles, which are the contours of the constant closed-loop magnitude. M-circles are defined as the ...
• 540
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### How to execute trajectory?

You have to choose a controller that best fits the system you are trying to control. You have to take into consideration the variables you are trying to control when deciding on the controller. ...
Accepted

### Time constant - formula

Does the book not give you the mathematics? The underlying expression is: $$parameter = 1-e^{ -t/ \tau }$$ so you see at $t = \tau$ $$parameter = 1 - e^{-1} = 0.63$$ Now the second sentence says ...
• 949
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### Why does a proportional controller have to have a steady state (offset) error?

If you open your drain valve, and then close it again, then you're correct, the tank will refill back up to 50, leaving you with no offset. If, however, the valve is left open, then the water may not ...
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Consider $s$ as a derivative operator. Therefore, $$\frac{Y}{X}=\frac{s+2}{s^2+0.5s+3}$$ looks like $$\frac{Y}{X}=\frac{\frac{d}{dt}.+2}{\frac{d^2}{dt}.+0.5\frac{d}{dt}.+3}$$ (\frac{d^2}{dt}.+0.5\...