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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122 views

Stability and Positive/Negative feedback

I often read that positive feedback is used to get oscillators (since the output of the circuit is summed up to its input signal and so leads to instability), while negative feedback to get amplifiers ...
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54 views

Stability of Buck Converter when output capacitance is variable

I am designing a buck converter for an application that has several different loads. Depending on what devices are connected, the capacitance seen at the output of the buck converter can vary ...
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3answers
174 views

Why “-1 + 0j” is critical point on Nyquist plot?

I am reading about Nyquist plot from this (http://www.cds.caltech.edu/~murray/books/AM08/pdf/fbs-loopanal_11Nov18.pdf) chapter. On page no. 10-2 its mentioned that "-1 + 0j" is critical point on ...
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329 views

How can I control TRIAC firing angle automatically with a DC voltage?

I have to build an analog proportional controller for a 127 V, 1 kW AC heating resistance. The power delivered to the heating element must be proportional to the difference between a set point ...
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25 views

Is it possible to predict the operating state of a power system (using MATLAB) if I have calculated the voltages at all nodes by state estimation?

If I have calculated all the node voltages by state estimation, is it possible to predict which operating state my system is at? By operating state, I mean any of the following: ...
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137 views

Buck-Boost converter without low side switch

Please look at the buck -boost converter below. It is 2 outputs, one buck and one boost output. Would the circuit work as describe in the picture? In what condition the circuit will it work? If so how ...
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41 views

Characteristics from transfer function

All! I am trying to figure out characteristics of a second order system The system is (for example) And its characteristics for an unit step input are I want to solve this equation by hand and ...
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1answer
788 views

Can a phase margin become bigger than 180° and is this bad?

I have a wrong mental model about phase margin in control theory. I see that a phase of -180° is bad. If my input is a sine wave and I have negative feedback, which has a -180° phase shift, the ...
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78 views

Steady error control system sinusoidal disturbance

Consider the control system closed-loop represented such a block diagram below: Given that: \$G_C(s) = K\$ and \$G(s) = 1/s\$ a) Determine the values of \$ K\$ which the closed-system loop is stable....
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150 views

Why am I getting non-sinusoidal output for sinusoidal input in a mass-spring system?

A mass-spring system is represented by the following transfer function $$ H(s) = \frac{s^{2} + 0.1s + 10}{s^{4} + 0.2s^{3} + 20s^{2}} $$ For a sinusoidal input I am getting a non-sinusoidal output, ...
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58 views

How do I refer the transfer function of a system from its Laplace equivalent?

I have a problem, I know how to analyze circuits in Laplace domain to get the transfer Laplace function. However, I don't know how to translate the answer to "real life" Suppose that I have a ...
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362 views

Why fast inner current loop and slow outer loop of DC-DC converter

Let say we have a DC-DC converter operates with double loop control (inner and outer) , and with switching frequency of Fs= 20000 Hz. Please ,if you could answer the two following questions: 1- ...
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1answer
184 views

PID (Arduino) Project - Determining Ki, Kp, Kd

I am working on control system project. I bought a Zumo 32U4. It has built in encoders. The project is divided into three parts: a) Move in a straight line. b) Slows down as obstacle approaches. c) ...
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428 views

Is the transfer function for the given RC network right?

For the question I arrived at the following answer (I have assumed V1 btw) Is my solution right? I just have a big doubt if whether I can use the voltage division rule at point A when there is an RC ...
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206 views

Relation between settling time and natural frequency for a critically damped system

In an article by Wie et al. (1989), for the purpose of calculating the gains of a controller, the equations of motion are approximated by the expression for a damped harmonic oscillation: $$\ddot{\...
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78 views

How to model a Electronic Proportional Control Valve

I am using a VSO LowPro Proportional control Valve (https://www.parker.com/Literature/Precision%20Fluidics/Miniature%20Proportional%20Valves/VSO%20LowPro.pdf) to regulate pressure into a closed ...
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1answer
243 views

What is difference between natural response and zero-input response of a system and how to find natural response?

In most books it is said that natural response is another name to zero-input response while in some resources is is mentioned that the classification is based on poles of transfer function and input....
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53 views

System Identification in a closed-loop feedback system [closed]

I have an unstable system that doesn't have a useable output when open-loop excitation is applied. Subsequently I've used a controller to control its output. I want to use the system identification ...
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3answers
76 views

Obtaining Plant Input data from System Identification (PID)

I'm trying to obtain a mathematical model from a physical plant using MATLAB. Using the system identification tool you need the plant input and output data. I'm struggling to match the theory to my ...
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1answer
159 views

Find transfer function and step function for this circuit

Can someone help me to find the transfer function of this circuit (i want to have the tension through the capacitor I think) and the step response in order to get the voltage in the function of the ...
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1answer
53 views

Gain deficit and phase margin at crossover

I went through an exercise of the following specifications: A voltage mode buck converter working in CCM mode works with: \$V_{in}\$ min = 10V, \$V_{in}\$ max = 20V \$R_{load}\$ min = 2.5 ohm \$R_{...
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56 views

how to control state space when it is not controllable?

I have the matrix A and B and I computed the controllability matrix and found the rank is lower than n. I know I can't apply pole-placement , how else can I solve the system? n is the order of A
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53 views

Transfer Function [ the transfer function of the feedback stage? (Optical sensor and the lm2917) ]

I have to make a control system that maintains a constant speed of a small car prototype using a DC Gearmotor regardless of external disturbances such as slopes (small slopes). For the development of ...
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1answer
64 views

What is the purpose of the capacitor in this circuit?

Is the purpose of the capacitor, C1, to filter out any possible DC component that the input signal has?
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1answer
63 views

How does force feedback [hardware] work?

Force feedback steering wheels are fairly common, but I don't understand how they work. Specifically, how does a "direct drive"($$$) steering wheel apply a force one way while moving in another ...
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2answers
233 views

What is the difference between these two op-amp circuits?

I don't understand why when we design a proportional amplifier, the feedback has to be negative. When I run the simulation in simulink I get the same result for both circuits.
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155 views

Power Supply : How to keep SMPS always above the post-regulator that follows it

I'm trying to find a way of building a new power supply for my workshop, in order to keep it small and not so hot I will be using a spare xformer to step down mains to 24v and then a variable buck ...
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2answers
144 views

Sluggish step response of control loop

I have a question regarding the PI controller. Lets say I have an actuator via which I control some plant. The control signal at the output of the PI controller is at its maximal realizable value. So ...
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4answers
773 views

Circuit Analysis: Obtaining Close Loop OP - AMP Transfer function

Trying to figure out the Close Loop System transfer function of an op-amp, however the math isn't working out as it should. Circuit In question: simulate this circuit – Schematic created using ...
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1answer
94 views

What is the difference between 'x' and 'plus' symbol in the block diagram

Generally speaking, what is the difference between the 'x' and the 'plus' symbol in a closed loop block diagram? For example, in (https://ieeexplore.ieee.org/document/6983570) , what's the ...
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1answer
65 views

How do I calculate this inverse Laplace Transform

I have this transfer function and input, and I have to manually calculate what the systems response will be. The transfer function is: and the input is: I multiplied the two functions and used ...
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1answer
276 views

Stability of a PLL

I try to design a analog PLL. I use a doubly balanced mixer as phase detector and a VCXO. The reference is a benchtop signal generator. So I currently try to design the loop filter, and I struggled a ...
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1k views

buck converter current control - how?

I am interested in understanding better how the regulation for a buck converter works, I don't understand it now and havn't found litterature really explaining it so far, so I am asking you here. The ...
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166 views

CANopen SYNC object and synchronous window length

In CANopen specification there is an object called Communication Cycle Priod [1006h]. This is the time interval between two consecutive SYNC objects. There is also another object called Synchronous ...
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3answers
994 views

In which way proportional valves are controlled solely by current?

Proportional valves are drived by current because we need a steady force and since resistance changes with temperature if they were driven by voltage this force wouldn't be steady. Ok, this is what I ...
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1answer
68 views

Confusion of terminology for control systems

I am confused about the following definitions (if there are any): Reference input reference signal setpoint reference I don't understand specifically what they are referring to. Do they refer to ...
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168 views

Optimum number of CANopen nodes in a CAN bus for motor control

I am studying about the CANopen implementation in a motion control work. CANopen is a protocol over tha CANbus. It is seen that, in the CANopen specification, theoretically at most 127 nodes could be ...
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3answers
885 views

Effect of RHP zeros on stability

Why do zeros in the right half of the \$s\$ plane reduce stability (i.e., gain / phase margin)?
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169 views

design a modular system, choosing bus and backplane

Our team has developed a several controller boards for our current Projects for over three years. With little modifications we have used this board in several projects so far. Its structure is as ...
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1answer
69 views

Moving summing block before integrator

I wanted to move the summing operation (+10) that I perform before the integrator block as shown below: (MODEL-1) I check in this wikibook page - https://en.wikibooks.org/wiki/Control_Systems/...
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254 views

The meaning of Bandwidth

What is the physical interpretation of "Bandwidth" in control systems not in filters? i.e What is the relationship between Bandwidth of a system and stability of a system??
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2answers
717 views

how to find frequency of oscillations if a order three system given

Frequency of oscillation in rad/sec of a unity feedback system having open loop transfer function G(s)=K/s^3+3s^2+4s+3 is
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4answers
1k views

Motor fader PID control

I'm trying to control a motorized fader (linear slide potentiometer) using an Arduino. PID control gives good results for "jumping" to a specific target position, but tracking ramps is a problem, it's ...
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1answer
432 views

Determining Number of states in State Space Modeling

I want to use state space modeling for representing the following circuit system. However, I am unable to decide the number of states. I am able to describe the system with a set of three equations. ...
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3answers
413 views

Root Locus, Gain in Feedback Loop. Need help

So this is the system for which I have to draw a root locus if 'K' changes from 0 to infinity. The problem for me is that root locus is drawn for open loop transfer function but 'K' is in the feedback ...
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2answers
165 views

Does the stability of an LTI system depend on the input?

Consider a system \$G(s) = \frac{1}{s}\$. It is marginally stable, as it has its only pole at \$s=0\$. However, if we apply a step input, the output is \$ tu(t) \$, which turns out to be unstable. ...
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1answer
196 views

PI controller - DC voltage regulation

I a voltage source converter, in order to control the DC-Bus voltage a PI controller can be used. The control method is illustrated in the figure below: I would like to ask why the input of the PI ...
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1answer
731 views

Constructing bode plot from experimental data and constructing a transfer function

I've been trying for a few days to convert an experimentally obtained (frequency against magnitude and frequency against phase) graphs to a bode plot and then construct a transfer function from the ...
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1answer
42 views

How do you reduce this simple system diagram for the sake of doing algebraic manipulation?

My guess is that since H(s) is parallel with 1(s) we'd do A(H - 1)? But this is my first ...
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40 views

What are some techniques to troubleshoot a second order sigma delta loop?

I have designed a slightly modified second order (3-bit) multi-bit incremental sigma delta modulator (IDSM) in simulink (system level). The SNR that I get is 45dB, which is not as expected. But ...

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