39 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 ...
Scott's user avatar
  • 499
27 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 ...
Chris Johns's user avatar
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14 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 ...
Wasabi's user avatar
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7 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 ...
Nuclear Hoagie's user avatar
6 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 ...
Cort Ammon's user avatar
5 votes
Accepted

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 ...
ConjuringFrictionForces's user avatar
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 $...
fibonatic's user avatar
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4 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 ...
useless-machine's user avatar
4 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 ...
Tiger Guy's user avatar
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4 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 ...
joojaa's user avatar
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3 votes
Accepted

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

The common denominator is that both "machines"/devices are transformers of some kind. What they do is transform energy from one form to another. However the total energy (if you ignore ...
NMech's user avatar
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3 votes
Accepted

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
Daniel K's user avatar
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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 ...
fibonatic's user avatar
  • 1,653
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 $V_1-V_5$, $V_2-V_6$, $V_3-V_7$...
Suba Thomas's user avatar
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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 ...
useless-machine's user avatar
2 votes
Accepted

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.
Suba Thomas's user avatar
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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 ...
Karlo's user avatar
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2 votes
Accepted

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, ...
fibonatic's user avatar
  • 1,653
2 votes

Frequency Response of a Discrete System

In matlab, using c2d (link) and bode (link) functions: ...
Vicente Cunha's user avatar
2 votes
Accepted

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 ...
user883521's user avatar
2 votes
Accepted

Problem finding value of the gain such that the closed loop is stable

To solve this problem I would: Sketch the block diagram of the control network. Derive the required closed loop transfer function in terms of $G(s)$ and $C(s)$. Substitute the expressions for $G(s)$...
user883521's user avatar
2 votes
Accepted

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 ...
Petrus1904's user avatar
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2 votes
Accepted

Incorporating a dichotomous failure model for sustainment analysis

Modeling future behavior using past behavior is fraught with pitfalls. This is why we test large numbers of parts before turning the factory on and stocking the product in the warehouse. That said... ...
niels nielsen's user avatar
1 vote
Accepted

What are the drawbacks of inceasing the bandwidth of the system?

The three main drawbacks for a high bandwidth are: Noise amplification. The higher the bandwidth, the more you are going to act on high frequent stuff in your error signal. Noise typically dominates ...
useless-machine's user avatar
1 vote
Accepted

Nyquist stability criterion for positive feedback

You could just multiply $H$ with minus one, change the positive feedback to negative feedback and proceed with the standard analysis for the Nyquist stability criterion. Here $H$ is the transfer ...
fibonatic's user avatar
  • 1,653
1 vote

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

In reality there is the data we have, and there is the data we don't have. Almost always, the amount of data we don't have is much much more than we could ever hope to gather for practical or ...
mathreadler's user avatar
1 vote

What is the engineering way to describe a factory / manufacturing plant system in a formel and mathematical way

Solar Mike is correct (as usual); the block diagram approach is the classic method for "formalizing" the dynamics inside a large and complicated system. However, it is important to realize that this ...
niels nielsen's user avatar
1 vote
Accepted

In what way the object-oriented methodology model an information system?

Object-oriented methodology allows representing the system as a hierarchical structure of self-contained subsystems and entities comprising it. This allows separate development and testing of the ...
SF.'s user avatar
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1 vote

What are the necessary qualitative criteria for the existence of limit cycles

Your (1) and (3) are along the right lines, but I'm not sure what (2) really means and some limit cycles don't look much like "regular orbits" anyway. There is always a danger in trying to produce a ...
alephzero's user avatar
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1 vote

System Dynamics Modeling

Deriving the system dynamics is systematically done using free-body diagrams, one diagram per body: The sign of spring and damper forces are easily determined by considering the motion of one state ...
drC1Ron's user avatar
  • 411

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