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17 votes
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Would a centrifugal flyweight governor system slow down the descent of an object that is free falling down to the Earth's surface? (Revised design)

Once the cylinder is released and starts to accelerate downward, the rotating flyweights should pivot upwards to a certain degree (as shown in the drawing) and should act as a drag on each of the ...
jpa's user avatar
  • 1,953
12 votes
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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 ...
Transistor's user avatar
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10 votes

Why are train brakes so complicated?

This answer addresses the following sentence: So I'd expect to see the brakes applied by a spring that is capable of stopping the wheels of a fully loaded car, and a single-acting cylinder that works ...
NMech's user avatar
  • 24.4k
10 votes

Why are train brakes so complicated?

You need to consider what happens if a hose bursts, and your spring-applied brake locks the wheels on one or more cars - how do you get that train back to the depot? There could be a manual brake ...
jayben's user avatar
  • 451
9 votes
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Units for rotational impedance

Radians and unit analysis The comment by MrYouMath is correct. For the purposes of dimensional analysis, the radian is considered a dimensionless quantity and therefore does not need to be included. ...
ConjuringFrictionForces's user avatar
9 votes
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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 ...
Olin Lathrop's user avatar
  • 11.4k
9 votes

If a control system is unstable does it mean it will oscillate?

An example of control system with non oscillatory response. $$ \frac{d x}{d t} = 0 + u\\ u = x $$ Closed loop equation of this unstable system is $$ \frac{d x}{d t} = x $$ and its response is $$ x(t) =...
AJN's user avatar
  • 1,134
8 votes

Minimal realization of a MISO system

One way of doing this is using the Kalman decomposition. For this you need the reachable and unobservable subspaces. These subspaces can be constructed using the image of the controllability matrix ...
fibonatic's user avatar
  • 1,653
8 votes
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What filter is this?

It might be written that way because the transfer function of a second order system is written as: $$ h(s) = \frac{\omega_n^2}{s^2 + 2\zeta \omega_n s + \omega_n^2} $$ where $\zeta$ is the relative ...
Mika Sundland's user avatar
7 votes
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Why does "Google self-driving car"'s roof camera rotate?

It isn't an ordinary video camera. It's a high-resolution LIDAR that uses laser beams to measure the distance to thousands of points on every rotation. I believe the one used by the car in that video ...
Dave Tweed's user avatar
  • 6,894
7 votes
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Why is it impossible to create an observer for this not fully observable system?

Observability means that you can estimate the complete state using only the output, without knowing the initial state. In other words, you have to figure out where you are without knowing where you ...
Daniel Nilsson's user avatar
7 votes

How are bode plots drawn for unstable systems with time delay?

You are absolutely right. Since the magnitude is the absolute value of the complex function $F(j\omega)$ the plot does not change with the sign of the pole or zero. The Phase on the other hand does ...
RaulG's user avatar
  • 71
6 votes
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When are overshooting controllers preferred over asymptotic ones?

For some systems, the salient criterion is settling time to within some error band. Sometimes you can get faster settling by allowing earlier overshoot. If you need a system to get to within some ...
Olin Lathrop's user avatar
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6 votes
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In Control Systems Engineering, why do imaginary poles and zeros on the LHP indicate stability?

Only the poles in the LHP are necessary for stability. This is because the transient response of a LTI system will consists of a linear combinations of $e^{p_i t}$. If a pole is complex, $p_i=\rho_i+i ...
fibonatic's user avatar
  • 1,653
6 votes
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Which equations of a state space model influence the poles and zeroes?

Half of your statement is correct: If we are considering the following system: $$G : \begin{aligned} \dot{x} &= Ax+Bu \\ y &= Cx \end{aligned}$$ then $A$, $B$, and $C$ all influence the zeros ...
BarbalatsDilemma's user avatar
6 votes
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Advantage of anti-windup

Anti-windup is a concept for feedback controllers with integral terms, e.g. PID, to keep the integral term from „overcharging“ when regulating a large set point error. It basically saturates the ...
OpticalResonator's user avatar
6 votes

P&ID Symbol identification, unknown meaning

This is an instrument symbol, they are read in the following way, ISA Symbology The symbology of the instrument it is placed in a circle of 7/16 “or 12 mm (see below), was in the top there is ...
DrMrstheMonarch's user avatar
6 votes
Accepted

What are these rotary to linear movements called?

This is a type of barrel cam, but also resembles a bayonet mount. Barrel cams consist of a cylindrical surface with a slot or raised ridge that wraps around the curved surface. As the cylinder rotates,...
Cowdozer's user avatar
6 votes
Accepted

Is the PID just an outdated control method and state-space is superior?

I do not think so. Instead of looking directly at PID, lets look at Frequency domain loop shaping in general compared to State-space control (eg, Lead-Lag filters, Notch filters and PID). On top of ...
Petrus1904's user avatar
  • 1,069
6 votes
Accepted

Nuclear weapon doubts

Electronics in today's sense didn't exist. The implosion explosives used a special sort of squib designed at Los Alamos. https://en.wikipedia.org/wiki/Exploding-bridgewire_detonator. There was a ...
Phil Sweet's user avatar
  • 4,765
5 votes

Understanding net torque from an actuator

There are two things going on. First, even if this "actuator" can produce constant torque, the torque required to keep the load spinning will be at least in part a function of the spinning speed. ...
Olin Lathrop's user avatar
  • 11.4k
5 votes
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A stable transfer function which diverges?

Without any more info, I think your problem arises from the values of $a_0$ and $a_1$. The answer is a little involved, so a bit of systems background is necessary. The short answer Your system should ...
BarbalatsDilemma's user avatar
5 votes
Accepted

Continuous time and Discrete time systems

A controller is built around a physical system. What is the open-loop behavior of the system? You have to sample the physical (continuous-time!) system in order to provide feedback to your discrete ...
Chuck's user avatar
  • 3,565
5 votes
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Are precision pneumatics possible?

While pneumatic systems can be controlled in a non-discrete manner as GisMofx mentioned, that is generally not the norm because the control system to achieve that movement is more expensive that ...
ericnutsch's user avatar
  • 8,181
5 votes

Can ultrasonic sound pass through solid medium?

Ultrasound partially reflects when it encounters a medium with different acoustic impedance. It behaves like light and obeys Fresnel equations. If the angle of incidence is smaller than the total ...
Nick Alexeev's user avatar
  • 1,035
5 votes

Open loop versus closed loop Model Predictive Control

I think the other answer is not complete. Model predictive control (or 'receding-horizon control' is a technique in which a predictive system model is used to evaluate a sequence of future control ...
Nicholas Moehle's user avatar
5 votes

How do I compute/plot the open loop transfer function of a system given its state-space description?

In order for the open loop to be meaningful the input to the controller has to have the same dimensions and units as the output of the plant, since normally when doing control in the frequency domain ...
fibonatic's user avatar
  • 1,653
5 votes
Accepted

Is this a PID cascade control loop?

I would not call this a cascaded control loop but rather a MIMO control loop. Typically a cascaded control loop has an inner and an outer loop and the output of the outer loop is used as the setpoint ...
user883521's user avatar
5 votes
Accepted

Which course to take? Optimal control? Nonlinear control?

In nonlinear control theory, you will recognize most concepts such as controllability and observability where the linear case is often a special case of the nonlinear case. I would highly recommend ...
link's user avatar
  • 98
5 votes
Accepted

Root Locus and Routh–Hurwitz stability criterion

Suppose we have a third order polynomial in the form : $$ s^3+a_2s^2+a_1s+a_0 = 0$$ There is nice caveat for third order systems which is derived from the Routh-Hurwitz stability criterion. In order ...
Teo Protoulis's user avatar

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