# 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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### 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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### Stability of a two poles negative feedback amplifier

let's consider this analysis of a two-pole amplifier with negative feedback (Microelectronic Circuits by Sedra Smith 7th edition): Before showing you my doubts, let's consider this introduction made ...
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### Closed loop impedance of buck converter

I found it easy to workout the open loop input impedance and the open loop output impedance of a buck converter. But when it comes to the closed loop output impedance, it is hard to me. In some books ...
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### Component connected in series in a block diagram of a control system

I am given the following block diagram of a control system (I think it also applies to electrical circuits as well with linear components. Correct me if I'm wrong). My textbook says that C(s) is ...
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### How can this problem be solved with partial fractions? (Zero order holder with g(s) block function)

im trying to figure out how to solve this problems for values a=2; actually im stuck, professor told me how to work it, but i cant figure out what to do exactly, we are using partial fractions inverse ...
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### Response of a RC circuit and Frequency Response Theorem

let's consider this important result of control theory for linear systems, called "Frequency Response Theorem" (reference): Briefly, it says that under the hypotesis of stability and linearity, if ...
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### How to find the gain K at break-in and breakaway points of a Root Locus Plot on MATLAB

I would like to know how to find the break-in and breakaway points of a transfer function using root locus on MATLAB. MATLAB Code: ...
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### In Distributed Automation System(DAS), which communication interface is used for communication between Remote Terminal Units (RTUs)? [closed]

A good data communication system to transmit the control commands and data between Distribution Control Centre (DCC) and a large number of device remotely located on the distribution network is a ...
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### PID controller slowly oscillates out of control

I am trying to tune PID controllers for my drone. There are 3 controllers, one each for Pitch, Yaw and Roll. I have gotten Yaw tuned to a reasonable amount and I am assuming the values for Kp, Ki and ...
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### Ziegler–Nichols method, use time value of 63% of process variable or steady-state level line?

I am attempting to use the Ziegler-Nichols method to PID tune a system. However, in calculating the tau/time constant value I have come across two different methods and am unsure which to use? ...
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### High level vs low level motor control - acceleration and velocity profiles

I was wondering how are motor control loops normally run? Lets say we have an autonomous car and a Model Predictive Controller defines a velocity and acceleration profile to get to the correct ...
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### How to find second order transfer function from a graph?

I have been given this step response graph and asked to determine the second order transfer function of the system. I completed the question, using a lot of help from this post and got the answers ...
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### Discrete time state space matrices for LQR tracker

How do we find the F(T) and G(T) matrices in this digital LQR tracker example? Here is the question from a control systems engineering textbook: And here is the solution: And here are the ...
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### Transfer function derivation from Op-Amp linear control system

Need to derive transfer functions for blocks B, C and D, unsure on the best method to do so. Any suggestions?
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### What is the best way to design an emergency button circuit?

I am using an Arduino ATMega as a controller and I have a few methods in mind to operate the emergency button (hardware and software.) utilizing the interrupt button while loop, with a pull down ...
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### How do I read a step response of the control effort?

I am trying to plot the step response of the control effort of two systems defined with two different controllers, and the plot is: I see that the system which is represented by the red line goes ...
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### Does the unit step response not affect the transfer function?

I am still confused, this question says that this figure shows three unit step responses and was asked to find the transfer function. Doesn't the input step responses only affect the output? So to ...
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### Advice on connecting heater directly to SP2 relay of PID controller?

I have an old Omega CN-9121 PID Controller and a 105Watts 115V Fibre heater mantle with an inbuilt K-type CHromel-Alumel temperature thermocouple also attached into it. I plan to use the PID ...
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### Interpreting basic contact and switch behaviour in a control system diagram

This might sound a stupid question but in a control system using buttons and contacts I have a bit confusion when it comes to picturing the real device. As an example if we have the following diagram: ...
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### Doubt on singular value decomposition

I am studying control systems and I am studying the topic of Singular Value Decomposition(SVD). I have found a transfer matrix of a systemm, and computed its DC gain. Then I have performed the ...
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### PI Compensator (for DC-DC Converter Control) transfer function derivation

Here is a PI compensator implemented using a OP-AMP. However, I'm wondering why Gc(s) = - vc/v, instead of vc/v. Not quite sure why there is a negative sign here since Gc(s) is defined as vc/v if I'm ...
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### State-Space-Model from more dimensional Transfer-Function

Im trying to extract the State-Space-Model for an cascaded Buck/Boost-Converter from an set of Transfer-functions $G(s)$ (which I generated with Plecs/Matlab). First of all I want to analyse the ...
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### When do the positive sequence negative sequence, and zero sequence apprea?

I have analyzed three phases current in different cases, but I am still confused about some cases. Positive and Negative sequences are appeared but not the zero. Zero sequences is appeared, while ...
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### Why does a pole at high frequencies attenuates noise?

I am trying to understand the concept of realizability for an improper transfer function, and I am struggling to understand some concepts. I know that if I have an improper transfer function, for ...
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### What is a non causal system?

I am stydying control systems, and I am trying to understand better the topic of causality. I know that a system is causal if the actual state depends only on the past states and on the present ...
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### Why if I add a pole at high frequencies to an improper transfer function it becomes realizable?

Suppose I have an improper transfer function, for example: $T(s)=\frac{s^2+1}{s+2}$ I know that this transfer function is unrealizable. Moreover, I have seen that to make it realizable it is ...
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### Eddy current damping compensation

I have a magnetically permeable element (98% pure iron) vibrating at 3-5Hz between two electromagnets (with iron cores) which is experiencing too much damping, presumably due to eddy current losses. ...
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### RHP zeros in control systems

In the slides of the following link is expressed the concept I am trying to understand : slides I am studying control systems. I have seen that if I have a zero in the RHP, by using decoupling I can ...
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### op amp stability theory

A little stuck and could use some help. This TI stability App Note on page 15 calculates the Thevenin equivalent circuit of a capacitively loaded op-amp and I can't figure out how they get that form ...
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### How to find the frequency responses for the below conditions in the eye model?

In the above image it says to calculate the steady state responses for a unit step response. But i need to find calculate the frequency response for the same model.
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### How do I find value of gain that stablizes the system from root locus?

Consider the following root locus: which is obtained by the following code: ...
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### Mixed sensitivity controller design

I am defining a controller using the mixed sensitivity approach, and I have the following specifications: a low frequency attenuation of 60 dB a maximum resonance peak of 2 and I have chosen to use ...
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### How is the closed loop transfer function defined for an oscillator?

an electronic oscillator is a device which can generate some signals without input signals. It is an unstable system realized with positive feedback, as shown in the following scheme: Now I have two ...
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### How to predict and compensate for the dynamic and static resistive torque due to losses in a motor

I will have external torques acting upon an axle to which a motor is connected. I want my motor control system to fairly precisely compensate for most of the torque that the motor imposes on the axle ...
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### Nyquist stability criterion for positive feedback

it is known that the stability of a system with negative feedback may be analized through the Nyquist stability criterion, which is based on observing the number of turns around the point (-1;0) in ...
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### How to find the critical gain K from the root locus

I am going through Ogata's Discrete-Time Control Systems and working out the following problem found on Page 262. The problem states: Draw root locus diagrams in the $z$ plane for the system ...