# Questions tagged [control]

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### Discretization of a controller

The desired control is $u_f=\frac{1+\eta s}{1+hs}a$, where $u_f$ is the feedforward control, $a$ is the feedforward observation and $\eta$ and $h$ are two constant parameters. However, I can only ...
37 views

### Are there control loops that attempt to maximize a process variable?

I'm working on Remote-Procedure Call (RPC) server that processes incoming streams of data from clients, and looking for a way to set a limit on the number of simultaneous streams allowed. There is ...
93 views

### How to deal with "weird" phase plots in bode diagram when designing a controller

I am trying to design a balance controller for a robot. With MATLAB simulink I arrived at the transfer function between the input and the pitch angle for the robot. I have plotted the bode and Nyquist ...
44 views

### Tuning a PID Controller

I have the following transfer function $$10000 \cdot\frac{(s-0.012)(s+1.05)(s-18)}{(s+0.22)^2(s+45)(s+1000)}$$ For which I am trying to tune a PID controller for. I'm using the pidTuner in MATLAB to ...
31 views

### Why do we use "error quaternions" for control of attitude?

I'm working on an attitude control system in terms of quaternions, and i'm basing my approach on the book Space Vehicle Dynamics and Control (2nd ed.). If we consider a proportionate controller, i.e. ...
52 views

### how to take a second order transfer function without any zeros and represent it using two first order transfer functions

does anybody know how to take a second order transfer function with no zeros (no s terms in the numerator): $$g(s) = K\frac{\omega_n^2}{s^2 + 2\zeta \omega_n s + \omega_n^2}$$ and represent it using ...
10 views

### Construct controller with given crossover frequency

I have this problem: I can solve question a) by looking for the phase gain of the bode plot at $\omega_{\pi}$, find the phase gain = 0.2, and divide $\frac{1}{|G(w)|} = \frac{1}{0.2} = 5$, so K can be ...
74 views

### How to quantify amplitude of oscillations in marginally stable systems?

Transfer function pole on the Imaginary axis indicates that the system is marginally stable which in time domain can be represented as a sinusoidal motion with constant amplitude and frequency of the ...
79 views

### Controller in the feedback path?

What happens if the controller of a closed-loop system is placed in the feedback path before the summation point, instead of between the summation point and the plant to control? Are we allowed to do ...
64 views

### How does the intuitive notion of causality fit in with control systems?

Edit: By causality, in this question, I do not mean the traditional mathematical definition in the theory o signals and systems; I mean causality as in an intuitive 'what's moving/pushing what notion'....
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### Region of root locus not inside the feasible region for a given performance specification

I wanted to plot the root locus for a system, whose plant transfer function is $$P(s)= \frac{k}{Ts+1}e^{-ts}.$$ A PI controller was suggested for this system, and the task is to find $K_p$ and $K_i$...
54 views

### Transfer function estimation using system identification

I am posting a control system problem here because of this post reference. Question: I have input and output datasets. These are graphically shown below. The blue line is output and the pink line is ...
27 views

### Control of a nonlinear static MIMO System

I am currently writing my master thesis and trying to design a controller for my system. However, the system is somewhat unconventional. It has a large number of inputs and outputs, is static, non-...
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### Controller design with DQ transform

I'm reading this paper on a 3-phase rectifier control. 3-phase rectifiers are usually connected to 50-Hz or 60-Hz grid. One popular control strategy is to transform the 3-phase currents and voltages ...
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### Feedforward disturbance signal compensation

The reference Feedforward control concepts through Interactive Tools says, to minimise the effect of the disturbance $d$ on the process output $y$, a compensator $G_{\text{ff}}=P_3/P_1$ shall be used. ...
111 views

### Stabilizing the inverse transform of a system

Currently I am trying to understand an unknown mechatronic system. I used white noise as an input signal and measured the output of the system. Then I estimated a second order SISO transfer function (...
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### Why if I place the zero of the lead compensator at lower frequencies, do I obtain a resonance peak?

I am studying control systems, and I am studying the lead and lag compensator. I have seen than if I use a lead compensator for the closed loop transfer function, $T(s)=\frac{s+2}{(s+1)(s+8)},$ with ...
32 views

### Measurement delay versus control delay

For a typical conventional control loop (no delay, measurement transfer function is 1) the closed-loop transfer function is $$H(s) = \frac{G_{comp}G_{process}}{1+G_{comp}G_{process}}$$ With an ...
104 views

### What does it mean that a zero is slow?

I am studying control systems, and have encountered the definition of a slow zero. I am searching on internet and in books, but I don't understand the meaning this. I know that if a zero is too slow, ...
38 views

### Does a RHP zero imposes some limitation in the time domain?

I am studying control systems and I have seen that a non-minimum phase zero imposes a limitation on the bandwidth, which is that the bandwidth has to be lower than the frequency which is half the ...
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### Problem in verifying zero blocking property of a zero of a multiple input multiple output system

I have a multiple input multiple output control system, and in particular a two inputs two outputs system. I want to find the zero state direction and the zero input direction of the system, which has ...
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### Is it possible to use a control scheme with a delay as prefilter?

I am studying control systems, and in my studies I have encountered the topic of control scheme of the form and I have seen thaht this control scheme is really useful since it is possible to add a ...
298 views

### Can a pole at the origin be considered a dominant pole?

I am studying control syetems, and I have studied that the dominant poles of a system are the ones closer to the imaginary axis. Now, consider a system with a pole at the origin. Can this pole at the ...
388 views

### Why does the control effort increase if the bandwidth of the system is higher then the bandwidth of the plant?

I am studying control systems and I am focusing on the control effort. I have seen that if I place a pole at higher and higher frequencies, if the bandwidth of the system goes above the bandwidth of ...
I've found this diagram in a slide, but i have no backround to properly understand it. Could you explain to me, in simple terms, how this process behaves and what's the purpose of the blocks $z^{-1}$ ?...