# 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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### 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. ...
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### Can I use a ultrasound sensor to measure water level?

If I use an ultrasonic sensor will it detect the water level? I was thinking about a product to read water level on water boxes (common in Brazil). I researched about instrumentation for this ...
288 views

### How do I solve an optimal control problem where the dynamics depend on some function of the state?

A typical optimal control problem with state $x(t)$ and control $y(t)$ can be expressed as $$\max_{x(t), y(t)} \int_0^{t_1} f(t,x(t), y(t)) dt$$ subject to $x'(t)= g(t, x(t), y(t))$ and boundary ...
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### PID controller explanation

I haven't found a text that explains the PID controller in simple words. I know the theory: that it calculates the derivative and the proportional gain and the integral etc, but I need to know in ...
269 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 ...
1k views

### Observability using the Discrete Extended Kalman Filter (EKF)

I have built (several) discrete Extended Kalman Filters (EKF). The system model I am building has 9 states, and 10 observations. I see that most of the states converge except one. All except 1-2 of ...
17k views

### What do you call the difference between the on and off temperatures in a simple thermostat?

A simple thermostat will turn on at one temperature and off at a higher temperature. This keeps the thermostat from cycling on and off too quickly. The difference between these values is sometimes ...
620 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 ...
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 ...
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### MIMO (multi input - multi output) system decoupling method

A MIMO system with 2 input and 2 output decoupling method to a SISO system is described in many articles and books. How about m*n size transfer functions systems? How can we generalize the method for ...
236 views

### Knowing how many times the rear wheels have rotated, and the angle of the front wheels at every time interval, how do I find the location of a car?

I'm making a robot for the Sparkfun AVC. I was curious if I could use only the knowledge about How the car is being steered at every time interval, How many times the wheels have rotated, to get a ...
7k views

### Block diagram vs flow chart?

I was studying a book on control systems where I read that a block diagram is a specialized high-level type of flow chart. What is the difference between a normal flow chart and a block diagram?
728 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 ...
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### How can I approach the application of control theory to real control systems?

I am an engineering student and I took my second dedicated controls class last semester. It was cool math and whatnot, but after all was said and done: I still have no idea how to make an actual ...
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### How do you set up a PID-Control if the time constants of the controlled system are variable?

The common description for a continous PID-controller is written like this: $$y(t)=K_p⋅e(t)+K_i\int_0^t e(τ)dτ+K_d\dfrac{de(t)}{dt}$$ The best value of the constants $K_p$, $K_i$ and $K_d$ for a given ...
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### 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 ...
327 views

### Automatic Shifting without Electronic throttle

I need to design an automatic shifting system, for a FSAE car. Clutch and shifts are electronically engaged and disengaged using a Pi Innovo engine control unit (ECU). The issue I am worried about ...
2k views

### How does one become a control systems engineer?

From what I understand, a control systems engineering job is almost always a senior level position. What kind of entry level jobs do most engineers have before they are qualified to actually design ...
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### A stable transfer function which diverges?

This question might sound stupid as I'm more of a software guy and never really had to do control engineering (besides the 101 classes). So I have a second order system I could approximate, with the ...
134 views

### When are overshooting controllers preferred over asymptotic ones?

Disclaimer Designing the behavior of controllers is an important task for many applications. Every application needs its own requirements fulfilled. For example a CNC machine needs a controller with ...
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 ...
149 views

### Linearization of dynamic equations/transfer function in control theory

I've gone through a control theory course, and after looking back at what we covered and how the subject was taught to us, I still have quite a few questions (which I unfortunately did not ask in ...
678 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 ...
290 views

### Could a water stream be used as a fiber optic sensor and detect when the stream is broken?

I have a small idea/project I am working on in which I want to use a water fiber optic sensor that can detect whether the water stream is broken and if so shut off the water. Having looked into fiber ...
1k views

### How do I invert a system in state space form?

Suppose I have a system described in state-space form. Can I invert the system (swapping the roles of the input $u$ and output $y$)? If we start with: \begin{align} \dot{x} &= A\,x + B\,u \\ y &...