37 votes

From an engineering point of view what are the downsides of a too accurate model?

Beware of overfitting. A more accurate model of gathered data from a system may not be a better predictor of future behavior of a system. The above image shows two models of some data. The linear ...
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  • 479
26 votes

From an engineering point of view what are the downsides of a too accurate model?

The most obvious downside is cost, all engineering projects have a finite budget and spending more money than you need to is clearly a bad thing not to mention wasting time. There can also be more ...
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13 votes

From an engineering point of view what are the downsides of a too accurate model?

There are a few reasons. From a purely pragmatic perspective, it's due to time constraints. The requisite time to solve a model increases far, far faster than the level of precision, and whichever ...
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10 votes
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Is systems engineer an IT profession or an interdisciplinary field of engineering?

Yes, you are correct that there are different definitions of Systems Engineer that vary by company. In fact, different business units of the same company may even use the term differently. A job ...
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9 votes
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Is there a term for a circular dependency in system design and engineering

If for some reason "circular dependency" doesn't work—it seems clear enough to me—you could also say that subsystems A and B are "interdependent" in their design. These are essentially synonyms and ...
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7 votes

Is systems engineer an IT profession or an interdisciplinary field of engineering?

I don't believe there is any conflict but variation in how Human Resource choose to define system engineer positions within specific organizations. It is my opinion that System Engineer has a broad ...
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6 votes

Is systems engineer an IT profession or an interdisciplinary field of engineering?

Systems Engineering pre-dates IT. The classical Systems Engineering has roots in aerospace industry (for better, or for worse). Projects were were getting multidisciplinary, and complex, and ...
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  • 1,045
6 votes

From an engineering point of view what are the downsides of a too accurate model?

An extremely accurate model may require a prohibitive amount of input data. It might be possible to generate an excellent model of weather systems, for example, by taking as input the position and ...
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5 votes

From an engineering point of view what are the downsides of a too accurate model?

"Too accurate" is not monotonic. It can actually create an illusion of fidelity which makes you think it's worth pumping more money into the simulation. This becomes very important when you're ...
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5 votes
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Square wave transfer function?

I thought I would expand a little on the answer offered by Karlo. Long story short, I would not try to calculate the analytical time response of a system to a square wave. That would be a serious ...
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5 votes

Is there a term for a circular dependency in system design and engineering

Another term that would be applicable is mutually reliant.
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5 votes
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What is micro-electromechanical systems (MEMS)?

One way to think of MEMS is regular mechanical systems, but at a very small scale. Often these tiny systems are fabricated using technology developed for making silicon electronic chips, like ...
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5 votes

Frequency Response of a Discrete System

If you want to evaluate a continues time transfer function at a specific frequency $\omega$ in rad/s you substitute $s$ with $j\,\omega$. For a discrete time transfer function you substitute $z$ with $...
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  • 1,603
4 votes

Fan Sensors (Tachometer vs Locked Rotor)

It's a trade-off between the simplicity of the sensor and how comprehensive the reported data is. The locked rotor sensor only reports whether or not the motor is spinning, not how fast it's spinning ...
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3 votes

What are the Singular Values of a dynamic system and how are they calculated in the *sigma* function in Matlab?

For a MIMO system $y(s) = G(s)d(s)$, with $m$ inputs and $l$ outputs. Consider a fixed frequency $\omega$ where $G(j\omega)$ is a constant $l \times m$ complex matrix. For the sake of simplicity the ...
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3 votes

What is micro-electromechanical systems (MEMS)?

MEMS is a semiconductor based process that can create miniature structures in silicon. When these structures (sensors) are subjected to mechanical stresses (pressure, acceleration, yaw etc) they are ...
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3 votes
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Doubt on zero pole cancellation

rlocus() takes the open loop transfer function as an argument, not the closed loop. i.e. G not T. Look at the documentation for rlocus here https://www.mathworks.com/help/control/ref/rlocus.html
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3 votes
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Problem with RHP zero in transfer function

This is because for all three of of your choices for the gain the closed loop system is unstable. Namely, for just an integrator as controller the gain should be below 1.5 in order for the closed loop ...
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  • 1,603
3 votes

Transformers and systems with gears have similar computation when having quantities refer to different parts. What is the general concept?

There is no general concept except for proportionality All you have discovered is that ratios are used throughout science and engineering. Simple machines (gears are only one example, you also have ...
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3 votes

Transformers and systems with gears have similar computation when having quantities refer to different parts. What is the general concept?

This is well known feature called the Mechanical - Electrical analogies. As name implies there are in fact several of these spanning several domains, not only does it apply to transformers and gears ...
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3 votes
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How does feedback implementation look like in a real word closed- loop process?

Microprocessors. The measured value from a sensor (either an analog voltage or any other digital processed value) provides the microprocessor with the current output of the system. Internally, this ...
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2 votes

Is systems engineer an IT profession or an interdisciplinary field of engineering?

sys·tem /ˈsistəm/ noun: a set of connected things or parts forming a complex whole, in particular. a set of things working together as parts of a mechanism or an interconnecting network. ...
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2 votes
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What kind of signal is the signum function? A power signal or an energy signal?

First point is that signum is not continuous with the jump at $t=0$. Second because of the absolute value in the integral it has the same $E$ and $P$ as a constant signal $1$. This means that $E_{...
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2 votes

Mechanical System Transfer Function - Systems Modelling

First off, the equations you have are not correct. For example, if equations 1 and 5 are added it results in $V_1+V_5=0$. The l.h.s of the first four equations should be $V_1-V_5$, $V_2-V_6$, $V_3-V_7$...
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  • 1,876
2 votes

MIMO (multi input - multi output) system decoupling method

I cannot give you the solution by using transfer functions. However I can give you a general form by using the state space representation. I will do it for a square system, i.e. the number of inputs ...
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2 votes
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How do I convert this mechanical system into a mechanical network?

I think what you have is correct, provided the friction and spring constants are inverses. I am more comfortable with the force-voltage analogy and would create the equivalent one as follows.
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  • 1,876
2 votes

Square wave transfer function?

You want to look for the Laplace transform of a square wave. Note: The transfer function $H(s)$ is the ratio of the Laplace transforms of output $Y(s)$ and input $U(s)$: $Y(s)=H(s)\cdot U(s)$ If ...
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2 votes
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Control System Question - spectra and their degrees of excitation

An impulse has a flat/constant power density for all frequencies. The impulse response of a system can also be used to characterize a system, namely convolution of the input with impulse response, ...
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  • 1,603
2 votes

Frequency Response of a Discrete System

In matlab, using c2d (link) and bode (link) functions: ...
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2 votes
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Doubt on bandwidth of a control system

There are many definitions of bandwidth. Typically it is determined from the open loop transfer function and not from the sensitivity or complementary sensitivity functions. Assuming a SISO feedback ...
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