# Questions tagged [control-engineering]

Questions about the models and theories of control engineering and the application of control theory to design systems with desired behaviors.

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### Is it a problem to have two heat sources controlled for different temperatures on the same heating circuit?

This is the situation - I have three heat sources, called CHP, burner 1 and burner 2 on the same circuit. All three feed to the same heating manifold, with various heat demands. Preferably I want to ...
181 views

### Terminology for setting Set Points to avoid "Contact Bounce"-like characteristics

What is the terminology for having different/spaced-out on and off set points for a particular controlled process? When a system does not have the set points set appropriately, it could exhibit ...
2k views

### How to improve a PID control loop by adding feedforward?

Assume you have a system model that is controlled by a PID controller (feedback). You want to add feedforward to improve the characteristics of the controlled system. How can you design the transfer ...
3k views

### What do the zeros of the transfer function tell you about a system?

I come from a mathematics background and I'm familiar with laplace transforms in-as-far-as they provide an algebraic method to solve ordinary differential equations. So, when I read about transfer ...
516 views

### Finding the zeros for a PID controller

I would like to know what I am doing wrong for this PID controller design problem. I have all the parameters calculated ($\zeta$,$\omega_n$,$\sigma$...) and I have my target point set up. But now I ...
72 views

### connectedness between the output voltage and input voltage

Given this circuit I want to deduce the relationship between the output voltage $U_A(t)$ an d the input voltage $U_E(t)$ using Kirchhoff's current law. We're allowed to assume that $R$, $L$and $C_1$ ...
219 views

### Details of the phase margin

In my controls class, we're covering phase and gain margins. We're asked to increase the phase margin of a given plant to greater than 45 degrees using a lag compensator. Initially, the phase margin ...
260 views

### Negative feedback Gain and Phase Margin

Consider the system with unitary negative feedback such that the open loop transfer function is $$G(s) = \frac{as + 1}{s^2}$$ a) Determine the value of $a$ such that the phase margin is 45º b) ...
4k views

### Determining Gain from a root locus plot

I was looking over practice problems for an upcoming exam and I am struggling with root locus. I understand how to plot the basic root locus but for some of the aspects when gain is asked to be ...
6k views

### Calculating a transfer function from a block diagram

I've been having trouble doing this school assignment. My professor has not taught the class how to read control block diagrams so I assumed that we were supposed to research on it. I've watched a few ...
128 views

### How does the DERIVATIVE term slow down the signal?

I look at PID controler and do not understand derivatve term. I know it's used in order to not let the signal to overshoot the set value. BUT when the sigal is arising, its derivative is positive. So ...
3k views

### Feedback control of two-link planar manipulator

TL;DR: how can I calculate the disturbance at each joint due to coupling forces in a two-link planar robot manipulator actuated by two independent DC motors? I'm studying control theory and trying to ...
712 views

### Why do the poles and zeroes of a transfer function cause a slope change in frequency response?

Why is it that as the frequency approaches a pole or zero of a system, the slope of the magnitude of the transfer function changes by 20dB/decade? Whenever I see this stated when reading about ...
345 views

### Is it possible to engineer water-walking boots?

A naive question, yes, I know, but it's something that has plagued me for a long time. Whether by secreting a substance, controlled vibrations, metamaterials, or powered systems, is it possible to ...
102 views

### Analog PID controller - settings wrt $V_{err}$ - setpoint always higher than room temp

I designed from scratch an analog PID controller to mantain a temperature selected in the range of 60 to 80ºC with a room temp say = 20ºC. The "plant" is a simple 4R7 5 W resistor heated by a PWM-...
1k views

### Determine the range of values for a PI controller

This is a basic control theory question, since Control Theory is a part of applied mathematics but also of engineering I was unsure whether to ask this here. The question says: Given the transfer ...
131 views

### Is there a way to obtain a circuit of some sort given a Nyquist plot?

I have some transfer functions and I was wondering if it would be possible to approximate this to an electric circuit equivalent. For example, given the Nyquist plot below, is it acceptable to ...
624 views

I am having trouble to calculate the differential equations of a simplified loading bridge. The system is build as shown in the picture below (just a sketch): If I use the Newton approach, I am ...
113 views

### How can a piece of steel rotated without any power input? [closed]

Currently I am trying to rotate a piece of steel >90 degrees without any power input. The piece of steel is attached on the wall. A servo is also attached on the steel. This question addresses ...
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### Second order system with additional pole

Why is it that a second order system with an additional pole or zero can be approximated into the general second order system for analysis? This was asked during our lecture and I am still looking ...
273 views

### What is the significance of a diagonal input in a control diagram?

I have seen several block diagrams with diagonal inputs, drawn with an arrow through the block. and others like that (via Google image search) What is difference between this and a typical signal ...
2k views

### What is the difference between direct and indirect learning control?

I found the following comments on direct and indirect control in "Survey on iterative learning control, repetitive control and run-to-run control." by Wang, Gao, and Doyle: There are two ...
734 views

### Types of state observers/estimators actively used in the industry?

Most introductory books on control theory usually start their state observation part by introducing the Luenberger observer, and after that they might continue by introducing the Kalman filter. When ...
376 views

### Modern method for teaching controls

Background When I took my first class in controls (2006-ish as taught by an aerospace professor for a mix of ME and EE students) it was basically all done in Laplace-transform, transfer functions etc. ...
274 views

### Controlling hydraulic cylinders with variable delay

Electro-mechanical systems typically used in robots have very low delays and are quite simple to build servo controllers for. Hydraulic systems are much less common in robotics and have delay due to ...
194 views

### In the context of a known disturbance $d(t)$ in a control loop, what is the $\Delta t$ at which the control loop has to be executed?

As an example, consider a P-T1-system with a PID-controller. First look only at the P-T1 system, set a $y_r$ and wait a long time - then we take a look on its output $x$ and see that it has still a ...
314 views

### Given drive rotation angle, controlling torque, how do I maintain movement speed with varied load?

I'm working on design of a 3D movement drive (for 3D printers/CNC mills etc) using DC motors and helical drive. A DC motor drives the leadscrew actuator which supports the working elements (head, ...
517 views

### Baffle vs Bottom Temperature Measurement/Control

In an industrial jacketed reactor, we have two temperature probes: one on a baffle the extends down about to the 50% fill line one built into reactor, very close to the bottom valve. When is it ...