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
136 views

Powering circuit with alternative and/or concurrent power sources

I have one of these led projectors which is normally powered by the embedded motion sensor. I want to be able to power it manually by a switch button. I need to do this in both alternative and ...
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1answer
389 views

Desired response of PI controller in motor vector controller

In vector control (field-oriented control) of motors (specifically induction motors), a rotating reference frame is attached to the rotor flux to give "DC" values in the current controller. This ...
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5answers
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Why is the frequency complex

When we take the Laplace transform of a function, why is the frequency (s) complex? I can not understand the significance of complex frequency. Please help or give some references.
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1answer
258 views

Need suggestions on control system engineering [closed]

I am sophomore studying control systems and the problems given in the books( like Norman Nise ) look too easy. Please suggest some good book with really good problems.
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287 views

How do I hold a signal high from one high pulse?

Assuming I send a signal wirelessly to a receiver connected to a fan. if the receiver detects that a pulse is there, it switches on the fan. the fan should stay on until it detects another high pulse, ...
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2answers
25k views

How to calculate Kp, Kd and Ki?

The motor operates within 140 rev/min to 600 rev/min. The controller gives an output in the range 4 to 20 mA. The sensor output reading equivalent to 400 rev/min, actual reading was 404 rev/min. The ...
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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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2answers
4k views

Cascading PID DC Motor Position & Velocity Controllers

I'm trying to build a robot with a differential drive powered by two DC motors. First I implemented a PID Controller to control the velocity of each motor independently. Estimated the TF using the ...
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1answer
4k views

SMPS : Average Current Control Vs Peak Current Control

Please correct my understanding. I understand that in peak current control mode, the slow outer voltage control loop generates a current command to the faster inner current loop. This current command ...
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2answers
203 views

Model and Control of a Physical System [closed]

Suppose i have a physical system (set of interacting elements ) that i want to control. Best thing we can do to understand this physical system and hence control it, is to model it. We end-...
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5answers
882 views

Kinds of Feedback

"Feedback is a process in which information about the past or the present influences the same phenomenon in the present or future" I find the idea of feedback quite fascinating and i could realize ...
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2answers
1k views

Time domain and Frequency domain

what is the difference between time domain and frequency domain components? How do these domains differ from each other?
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7answers
1k views

Control theory basics

I'm trying to understand something very basic about Control Theory. Let's say I have the following loop: If we'll relate this loop to a cart with a motor going in its single axis from X = 0 to X = 50,...
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1answer
669 views

When the Gain Margin is negative, for what range of frequencies is will the output resonate out of control?

If your system/transfer function has greater than zero gain for the frequency associated with -180 degrees phase, the system is said to be unstable. What does this mean for other input frequencies? ...
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1answer
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Practical Limit of Feedback Control Systems WRT Bandwidth

In a digital feedback control system, I'm interested in the practical limit of what the correctable bandwidth is. For example, given a very simple system: A sensor can sample a simple X position ...
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1answer
1k views

Digital Control Engineering book recommendations [closed]

What are good books on digital control engineering specifically? I'm a third year electrical/computer engineering student who will be doing a course on digital control next semester, but would like to ...
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3answers
678 views

Step response to feedback loop with disturbance

When using step response to a feedback loop with disturbance. Why do we analyze the step response of the disturbance D and the step response of the input R separately. Instead of considering them ...
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3answers
1k views

Why do digital controllers need A/D and D/A converters?

One of the questions in our final exam will be "Explain the need of A/D and D/A converters in digital controllers". I could not find the reason anywhere why the Plant part of a block diagram requires ...
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2answers
93 views

Is there any correlation between eigen functions and eigen vectors of an LTI system?

Eigen functions are the origin for Laplace transform while eigen vectors is for state space representation.Can we relate the eigen concept in these two? The complex exponential functions, are eigen ...
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2answers
63 views

Controlling LEDs with multiple controllers [closed]

I have three black boxes each controlling an LED output. Each black box takes an input voltage and provides an output voltage (ranging from 0-12V) to illuminate the LED. Is it possible to alternate ...
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1answer
1k views

Switched Mode Power Supply : Voltage Mode Control and Error Amplifier Output

I am trying to understand how regulation happens on Cycle-Cycle basis in the case of Voltage Mode Control (VMC) and Current Mode Control (CMC). I understand that in the case of VMC, an error ...
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1answer
735 views

transfer function and error gain function

simulate this circuit – Schematic created using CircuitLab I know the difference between those two functions , but i want to see the relation between them , i think that the error gain function ...
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1answer
3k views

PID gains from the transfer function of a plant

I am trying to calculate gains ( Kp, Ki, Kd ) of a PID controller. I have to improve the response of a plant. I already have the Transfer function of the plant. I was wondering if matlab has some ...
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2answers
745 views

Does the use of PID controller require knowledge of plant's Transfer Function

As simple as that. I assume that you use PID when you do not know the Transfer Function of the system, otherwise you use it and plug it directly in the closed-loop control.
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2answers
432 views

Overshoot control

Suppose I have the following step response: $$y_{step}(t)=\frac{kP}{1+kP}(1-e^{\frac{-t}{\tau}})$$ where k is constant and P is the plant. How may I determine the values of k for which there would be ...
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1answer
68 views

Can you implement a control algorithm and send the inputs via xbee?

I know this question is little bit vague, but let's say that I have a robot or a quadrotor to control. I want to implement the control algorithm (PID, robust, or LQR) in the PC not in the robot/quad, ...
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1answer
2k views

Astrom-Hagglund Relay PID tuning - relay transfer function?

I'm implementing a PID temperature controller on a PLC. To cut down on installation time (this design may be reused many times), I want to have the PID parameters tuned automatically rather than ...
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5answers
1k views

System response types

Whenever I am given a system type with a certain transfer function, I am always asked to proceed to find out the 1. impulse response and 2. step response of the system. My question is, what is so ...
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2answers
118 views

Control and transfer functions

I would like to determine the following transfer functions: $$T_1=\frac{y^\wedge}{d^\wedge}$$ $$T_2=\frac{y^\wedge}{r^\wedge}$$ $$T_3=\frac{e^\wedge}{d^\wedge}$$ $$T_4=\frac{e^\wedge}{r^\wedge}$$ In ...
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1answer
647 views

Interfacing Matlab with a NI real time target (cRIO 9073)

I currently have a control system implemented in Matlab that controls a vehicle. The tracking is performed using an overhead camera, and commands are sent to the vehicle via xbee. I have now added a ...
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2answers
4k views

Proportional controller

Sirs, I am not able to understand why Proportional controller introduces offset.Please consider follwing paragraph I found on internet, credit to ** http://blog.opticontrols.com/archives/344 **, ...
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1answer
246 views

When is a programmable logical controller the best choice? [duplicate]

I am studying PLCs as a part of my Elements of Industrial Automation class. Trouble is, I can't imagine why would anyone use such a thing. For complex tasks, microcontrollers are available. The vast ...
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2answers
526 views

Pole-zero cancellation Paradox

Suppose we have an open-loop transfer function $$G(s) = \frac{1}{s(s+a)(s+b)}$$ If we plot the root locus for the closed-loop system we will get roughly something like this : Now the question is ...
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3answers
204 views

How can we find transfer function of this n/w

How can we find the transfer function $$\frac{E_0(s)}{E_1(s)}$$ of this RC network simulate this circuit – Schematic created using CircuitLab
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0answers
194 views

PD control (PID without I) - Homework help

I've been given a system - x" = bx′ + kx + ru and I've been asked to rewrite it in the canonical form x' = AX + BU. I've got -- ...
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1answer
128 views

Linearity and time invariance

If the input of an unknown system is shown by: \$x(t)= u(t)-u(t-1)\$ which results in the following output: \$y(t)=u(t)-u(t-3/2)\$ then what can be said about the linearity and time invariance of ...
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1answer
652 views

Derive transfer function from block diagram

I have this block diagram which I already reduced pretty much: Now I want to derive the transfer function from phi_o1 to q. ...
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1answer
2k views

Difference between online PID and offline PID tuning?

I've been reading about PID control on the internet lately (Wikipedia). I came across the words 'online' and 'offline' in PID tuning. I googled it but couldn't find anything. What does this mean in ...
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1answer
862 views

how to make a system respond to IR laser? [closed]

Lets say i have 2 separate systems called Box A and Box B. Box A has an IR laser beam attached to it. What equipment can i use to make Box A make a certain action ONLY when the IR laser attached to ...
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1answer
255 views

Affine Non Autonomous State Space system

Normally We all know the state space model of the the form der(x) = F*x(t)+G*u(t) y = H*x(t)+J*u(t). However I came across a state space model which has the following form der(x) = F*x(t)+G*u(t) + ...
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2answers
3k views

Open loop vs closed loop in control theory

I have two questions: Why we study stability in open loop rather than closed loop (which is the system that will be implemented). and is there a relation between response time in closed loop & ...
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3answers
171 views

Control System - Changing damping on-the-fly?

I'm trying to implement a PID algorithm on a microcontroller that controls an actuator with a hard physical limit. In MATLAB, there's no consequence to large overshoots/hitting saturation at high ...
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3answers
3k views

Describing step response in terms of poles and zeros of transfer function?

me and a friend are stuck describing something, we're both coming to terms with using matlab and we're trying to understand the design of a simple control system for controlling the steady-state error ...
2
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1answer
102 views

Exclusive control over actuators

I feel kind of stupid asking this question, but after unsuccessfully searching for papers and then starting to draw my own solution with a lot of XORs to the following problem, I started wondering ...
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2answers
145 views

External programing of an mcu without Hex

We need to change a controller code from the out side as they do with industrial MCU. So that you have an MCU, with a program on it, and someone can program some "words" to it, that will determine how ...
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2answers
2k views

How should sampling frequency, switching frequency, control loop update frequency, and anti-aliasing filter corner frequency relate?

Suppose one is designing a processor-controlled switching supply. In general, how does one properly select switching frequency vs. control loop update frequency vs. feedback sampling frequency vs. ...
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1answer
336 views

Is impulse response always differentiation of unit step response of a system?

I was trying to solve a question in which the transfer function of a system was asked, its unit step response being given: $$ c(t) = 1 - 10^{-t} $$ The method that the book followed was to first ...
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3answers
13k views

What should be DC gain of the system?

Step response of system is \$c(t) = 5 - 0.5e^{-2t} + 8e^{-t}\$ then find steady state gain. Answer is -7.5 Now in book solution is given as : Since this is step response we will find impulse ...
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3answers
2k views

How does control theory apply to my real-world processor-controlled boost converter?

I have a limited understanding of control theory. I dealt with poles and zeroes and transfer functions in school. I've implemented several microprocessor-based control schemes for DC/DC converters. ...
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2answers
89k views

What is a “dry contact input”?

I'm a PC software guy, a newbie to electronics. Recently, I've got a project in which I need to source for a DAQ that can provide dry contact inputs to an interfacing digital output controller. The ...