Questions tagged [control-system]

A system that may be electronic circuits or even software that uses control theory (principally differential equations) to control an output by monitoring various aspects of the system under control and varying inputs all towards meeting a defined goal. Some famous examples are controlling a rockets thrust angle to ensure directional control.

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1answer
58 views

Feedback systems using passive systems

I started reading control system (book) just a few days ago , In the derivations of equivalent transfer function of Cascade or feedback connections it assumes that "The subsystem connected to ...
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4answers
68 views

Why is the error in control system calculated against input?

In control system, the error is the difference between input and output. But why are we expecting to get the output same as the input. To get the exact input as output there is no necessary for the ...
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1answer
115 views

How can I use MC1489?

I would like to use the interface on link below. I tried to do exactly same except output because to test first, I gave output to LED from microcontroller. My question is with MC1489. When i connected ...
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6answers
11k views

How to learn PID Control?

I want to learn PID (Proportional–Integral–Derivative) control mainly for temperature. I would like to learn preferably through an easy project to do. Could you please recommend something which ...
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1answer
55 views

Help needed using convolution to calculate a system's impulse response

I have a circuit with the transfer function \$G(s) = \frac{1}{(s+1)^2}\$ and I'm asked to calculate the impulse response of the circuit. After looking into it I know that I need to use convolution ...
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1answer
290 views

Gain of an experimental first order step response

I have a pwm driven DC motor control system with magnetic encoder that measures the output shaft speed and outputs the RPM values every 50ms over serial comms to plot a graph of RPM vs Time. The ...
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6answers
365 views

Control Loop Stability - Crossover frequency

I am testing the control loop stability of a DC-DC Converter. One of the Pass-criteria of the DC-DC Converter states, "Cross over frequency should not be higher than 1/8th of switching frequency" ...
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1answer
2k views

Relationship between switching frequency and controller's crossover frequency in buck SMPS

Context: tuning the control loop of a buck SMPS. I specicifally have a TI TPS40200-based circuit in mind, but I think this applies to SMPS design in general. Quoting from Type 2 compensation network: ...
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3answers
542 views

How to estimate settling time of an overdamped system?

I've been trying to figure out how to estimate the settling time of a second order system in response to a step input of magnitude 5. The systems transfer function is $$G(s) = \frac{1}{(s+2)(s+4)}$$ ...
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1answer
53 views

Advice needed for a final year project on wheelchair automation and control

My project partners and I have been trying to design a wheelchair for people with neuro-degenerative diseases. I know this has been done in the past, however we are using a different approach. We are ...
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1answer
85 views

Regarding PLC and several input/ output modules

I have to use more than 40 servo motors and 20+ load cells using PLC. But the problem is that I have to use many I/o modules ( that is costly and hectic). Can I reduce the no of I/o modules by any ...
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61 views

Laplace vs Fourier Transforms in Transmission Lines

Consider an electric transmission line with transient equations $$\frac{\partial v}{\partial x} =-Ri -L\frac{\partial i}{\partial t}, \qquad \frac{\partial i}{\partial x} =-Gv -C\frac{\partial v}{\...
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2answers
332 views

A current controller by regulating the voltage

I need some idea of what type of controller I should use. But, I am thinking of a PID controller. Here is my problem: I have a simple circuit like this one: simulate this circuit – Schematic ...
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3answers
156 views

How to do the bode plot for this function without Matlab?

I want to plot the bode diagram without any software for $$G(s)=\frac{(s-2)}{(s^2+4s+15)(s+2)}$$ I do not know how to deal with the factor of \$s-2\$ I will be appreciate if someone can show me your ...
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2answers
168 views

Multiple output Flyback - Stacked transformer - Cross regulation - TL431

Suppose I have the following output stage of a flyback: simulate this circuit – Schematic created using CircuitLab The schematic is a bit simplified but the idea is here. Do not pay attetion to ...
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1answer
37 views

Control software for three phase induction motor

I have been writing a control software for field oriented control of three phase induction motor. As far as the platform I have been using the FreeRTOS real time operating system. My plan is to ...
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2answers
285 views

zero of spring-mass system

I was reading this PDF which tries to explain the concept of poles and zeros of Laplace transform. I started with second paragraph on page #590 and read it up to page #592 before the new section "...
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1answer
1k views

how the area is exactly zero?

I was reading this PDF which tries to explain the concept of poles and zeros of Laplace transform. My question is about FIGURE 32-5(b) on page #591. I don't understand why the area is said to be zero ...
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0answers
64 views

Finding roots of undamped and damped time domain response of a 4th order characteristic equation

A fourth order system is expressed in terms of the characteristic equation as \$s^4 + 8s^3 + 24s^2 + 32s + k = 0\$ Using the Routh’s array criterion determines the value of the gain parameter k and ...
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1answer
28 views

STEP7 MICROWIN PLC Ladder Diagram

I draw like the first figure in the program, but when I save the program it automatically becomes the second shape. Do the two mean the same thing?
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1answer
39 views

Matlab transfer functions

I used the "c2d" to discretize a transfer function initially but MATLAB automatically took it as zero order hold because I didn't specify any kind of hold. The result for the zero order hold is ...
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2answers
66 views

How can a system reach its steady-state if the I-action of a PID controller, u(t), doesn't go to zero as the system approaches its desired value?

The I-action of a PID controller, which integrates the error over time, results in the control signal: $$u(t) = \int_0^{t}e(T)\text{d}T$$ This means that, when the system reaches its desired value ...
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1answer
48 views

Bode plot display in matlab

I would like to display a bode plot of a buck-boost converter using Matlab, so I got the figure shown below, If we look closer to the phase plot, we see that it starts from 360°. My wish is to make ...
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0answers
36 views

Does a circuit graph say anything about controllability of its currents?

Graph of an exemplary circuit can be found below. Based on this graph, can anything be said about controllability of the edge currents ED, AN, BN and CN if the edges DA, DB, DC, AE, BE and CE ...
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1answer
296 views

How do i go about finding the transfer function of this system with two inputs?

This was how i tried to formulate the answer but ive been told its incorrect. $$R(t)=u(t)$$ $$D(t)=u(t)=1/s$$ $$K=10$$ $$H=1$$ $$G=\frac{K}{s(s+1)(s+2)} =\frac{K}{s^3+3s^2+2s} $$ If someone could ...
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1answer
69 views

Centroid from calculated root locus is different to the one from MATLAB

Hi all hope someone can help me here. My problem involves the transfer function G(s)=(s+32.8)/((s+2.8)(s+5)(s+27.8) ) As far as im concerned the centroid is ...
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0answers
67 views

Problem understanding transfer functions of second order filters

The transfer function of any second order filter can be found by analyzing the circuit using the Laplace transform. For example the transfer function of a second order low pass passive RLC filter ...
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1answer
89 views

draw a block diagram for the system

A system is represented by the following equation: $$\frac{𝑑^2𝑥}{𝑑𝑡^2} + 8\frac{𝑑𝑥}{𝑑𝑡} + 9𝑥 = 1$$ By taking the initial conditions, 𝑥(0) = 1, 𝑥̇(0) = −1, draw a block diagram for the ...
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1answer
269 views

Tuning PID coefficients for stationary stability of brushless DC motors

I'm using a commercial off-the-shelf brushless DC motor controller. It combines a PID controller and an absolute encoder to regulate position. When my motor reaches its target state, it generates a ...
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2answers
68 views

Zero in a basic RC high pass filter

If I write the transfer function I can clearly see a zero at zero frequency and a pole at 1/2πRC frequency. But If I simply look at this circuit I would say that there is one pole and no zero(as there ...
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2answers
65 views

Proof for Peak Time for an Underdamped Second-Order System

I've been attempting to prove the taught result that: $$T_p=\frac{\pi}{\omega_n\sqrt{1-\zeta^2}}\textrm{.}$$ From the time-domain form of an underdamped response, we have $$c(t)=K_1e^{-\sigma_dt}\cos(...
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1answer
131 views

What is the gain margin of the system, when the phase crossover frequency does not exist?

I have a simple questions I have a system in which the system will never reach -180 degrees for any frequency. Does that make the gain margin infinite ? If yes, does that mean that the system will ...
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0answers
92 views

Desing a PI controller for process with complex conjugate poles

I have a dual-loop control system. In the inner loop, the process is represented by a first-order transfer function. For control I use PI controller. Open loop transfer function is: $$ G_\text{co}(s) =...
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2answers
192 views

Phase margin vs. damping ratio (non-unity feedback)

So there is a well known condition which relates the phase margin with the damping ratio for a unity feedback system: $$\Phi_m = \tan^{-1} \frac{2 \zeta}{\sqrt{-2 \zeta^2 + \sqrt{1+4\zeta^4}}}$$ ...
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0answers
44 views

RTOS understanding and communication

We are working on a system that will need some predictive emergency stop. As a possible solution the RTOS was mentioned. Not sure if RTOS is a way to go, might just be that we do not have full ...
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1answer
58 views

How to find the phase of this transfer function?

I have been trying to find the phase of this transfer function: G(jω)H(jω)=0.1695/jω(5.88jω+1) by doing this: Phase = -arctan(0/0.1695)-arctan(w/-5.88*w^2) PHASE = 0-arctan(1/-5.88*w) Is this ...
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3answers
98 views

Feedback response in linear system

I have a linear system with transfer function \$G(s)\$ that is connected in negative feedback with a real value gain \$K\$. Therefore the open loop transfer function is \$K \cdot G(s)\$ and the ...
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3answers
93 views

Finding the impulse response from the integral

I'm trying to solve the part (a) of the following: I know that: $$ y(t) = \int_0^1 \! \delta (t-\lambda ) \mathrm{d}\lambda $$ But I'm not sure how to proceed from that.
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1answer
376 views

Closed loop vs. open loop system analysis and design

I have found questions similar to mine in the forum but none were quite answered to my full satisfaction. I have two questions: 1) Why is controller design is traditionally done with the open-loop ...
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0answers
17 views

Determining closed loop stability by nyquist criterion

G(s)H(s)=2.2/s(s+1)(s^2+2s+2) how to determine the closed loop stability using the nyquist criterion and how should I start implementing on matlab
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39 views

How can we plot Non minimum Phase system Root Locus?

I have a closed-loop transfer function $$ H(s)=\frac{K(2-s)}{s(s+18)}.$$ I know that this is Non-Minimum Phase system, but I could not determine the points that cut through the real axis, the ...
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2answers
38 views

Control system basic feedback loop, what's happening at the initial state?

How can the system output be dependent on itself, when at the initial state there is no system output? I don't understand how it can work physically.
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54 views

How to fix triac control module?

This is scheme of triac control module. I'm using optotriac MOC3041 (T1 on scheme) and triac BTA140 (T2 on scheme). Is it possible that my control module doesn't work correctly due to too small ...
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3answers
159 views

Best way to track light source?

I want to build a 1-D (azimuth), bidirectional optical tracker. The idea is to have two identical transceiver, mounted on DC servo-motor. The user can move the two servos on rails (reasonably fast), ...
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1answer
104 views

How to determine the settling time from a transfer function?

Given the transfer function \$G(s)=\frac{(1-\frac{s}{3})}{(\frac{s}{0.1}+1)(\frac{s}{100}+1)^2}\cdot 10\$, I would like to calculate the settling time. From what I've learned, this is a third-order ...
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1answer
42 views

Is Integral gain much use with a frequently changing setpoint?

I have a motor/encoder setup with a PI loop, where the motor needs to travel to a certain position following an accel/decel profile. The setpoint in this case is position at time T, which changes each ...
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2answers
68 views

Help with a Closed loop and zero order hold function ZoH * 1/s(s+a) type

i would appreciate some help in solving this problem, i need to find the transient response for a unit step, i have a brief idea of how to solve, but my graphs in matlab doesnt seem to fit with the ...
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3answers
152 views

How does an active filter transfer function translate to a block diagram?

I am having troubles trying to translate when finding a transfer function of an active filter is it in a 'Close loop' or 'Open loop' state? When finding the transfer function of these active op-amps ...
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3answers
173 views

Ultra-narrow beam spread LASER diode

I want to build an optical position tracking system based on PSDs (Position-sensitive detectors). I searched online and found this PSD which has a sensitive area of 12 mm*12 mm. My goal is to allow a ...
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0answers
71 views

Converting an analog Butterworth filter into a discrete filter

Here again to ask about another question. This time asking how to convert an analog transfer function to a discrete transfer function using standard continuous to discrete methods. The application ...

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