# Questions tagged [control-systems]

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### Are systems considered causal if they depend on prediction of future inputs?

A causal system is a system whose output only depends on the present or the past inputs. But there are many systems that do a look-ahead prediction and involves that in the calculation. For example, ...
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### Peak prediction

In my block, I am changing the gain of Amplifier (PGA) in step of +/- 1dB depending on the control voltage derived from the AGC (Automatic Gain Control). But can I change the gain of PGA in one shot ...
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1 vote
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### Why power metric is used for AGC control signal instead of some other metric like peak?

I am just understanding AGC : As per my understanding, AGC is a digital block which controls the gain of the amplifier, placed after ADC, such that ADC doesn't clip the incoming data and maintains ...
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1 vote
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### Trying to replicate results from tfestimate function in Matlab

I have been trying to replicate the results from the tfestimate function in Matlab by performing, from my understanding, the corresponding signal processing steps in a separate Matlab script file. The ...
13 views

### Advantages of Euler vs Quaternion vs Axis-Angle Paramertization

I have spent a bit of time studying attitude estimation and I noticed that uncertainty of orientation can basically be represented in three forms. Euler angles, Axis Angle and Quaternions. Quaternions ...
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### Smoothing sensor signal with discontinuities on DSP for obtaining signal derivative

I am trying to implement PID control on a sensor signal that has many discontinuities in it. Due to these discontinuities, the differentiated signal does not provide a meaningful or useful signal I ...
1 vote
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### truncating a system and plotting it on bode

Let system G(s) be: $$G(s)=\sum_{i=0}^{10}\frac{(-1)^i}{(2i+1)^2}\frac{\omega_i}{s^2+2\zeta_i \omega_i s+\omega_i ^2}$$ $$\omega_i=\frac{(2i+1)\pi}{T}\, T=1\, \zeta_i=0.2$$ Its impulse response is an ...
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1 vote
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### Is heat equation considered as LTI system?

The heat equation $$\frac{\partial u}{\partial t} = \alpha \nabla^2 u + f(x,t) \tag 1$$ Here, $u$ represents the temperature field, $\alpha$ is the thermal diffusivity of the material, $\nabla^2$ is ...
1 vote
179 views

### 2nd order Z transform system [closed]

Related to this. I have been into exploring the world of digital control loop but I have encountered a very simple problem. The unity negative feedback transforms a system which delays a signal by 1 ...
102 views

### Performing experiment on a digital control system

I want to perform experiment(s) on a digital control system. I have several questions: In analog control systems, the adder is usually an operational amplifier. However, since here the system will be ...
27 views

### Desired trajectory generation from transfer function in control theory

I am trying to implement the backstepping techniques for quadrotor described in this article : Backstepping control for a quadrotor helicopter: Madani & Benallegue 2006 Since I am new to the ...
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1 vote
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### Why lag compensator is preferred over PI for sinusoidal reference?

In this post, LJSilver mentioned that a PI compensator is not appropriate for a constantly changing reference, such as a sinusoidal waveform. In this scenario, a lag compensator is considered the ...
• 131
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### how does steady-state error decrease as the pole of the compensator moves closer to the origin?

The steady-state error improves when the pole moves closer to the origin, as seen in lag or integral compensators with step input. Is there an intuitive explanation for this phenomenon?
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### PID Tuning for 6 degree of freedom robot with ROS

I'd like to start by saying that I'm pretty clueless about controllers, control theory, or really anything to do with this subject. I'm a programmer, but I'm part of a project involving a 6 degree of ...
1 vote
64 views

### Mixer and control systems

A mixer in the time domain usually multiplies 2 signals of the time domain , however what does it do in the Laplace domain?Is there a equivalent block diagram of a mixer in the Laplace domain?The ...
• 153
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### control system : time domain analysis

This is the question. According to this, when we solve for transfer function we will get $20/s^2+5s+24$. but this is not the correct format as numerator should be equal to the last term, i.e., 24, in ...
1 vote
120 views

### Why a differentiator is unstable from pole zeros view point?

A differentiator with frequency response $j2 \pi f$ is unstable because as frequency increases its response becomes out of bound. But from a pole zero point of view a differentiator just have zeros ...
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### How to choose sample offset values in timing synchronization for a QPSK demodulator?

I am implementing a timing synchronization loop for a QPSK demodulator. I have chosen to use a Gardner timing error detector, which has often been mentioned. I am about to close my loop and I am ...
214 views

### How do I reduce a block diagram with just a line as a feedback loop, I dont get how it adds K to the denominator

How do I reduce a block diagram with just a line as a feedback loop, I dont get how it adds K to the denominator. The bottom equation is supposed to be the answer.
1k views

### Transfer Function Estimate

This is related to this post: https://engineering.stackexchange.com/questions/56050/obtaining-the-open-loop-gain-estiamte-the-gain-and-phase-frequency-response Using python, I would like to write a ...
12 views

### Difference between H2 control and input shaping

Let us assume a system with external disturbance to reject. The system that is used for controlling has vibrations, that we would like to avoid. We assume moreover that the dynamics are known (10% ...
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### Direct and numerically robust conversion from zero-pole to state-space representation

Note: this question was initially asked in a different community. Encouraged by the comments, I decided to cross-post here too. Given (z,p,k) my goal is to convert to a state-space representation (A, ...
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1 vote
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### Finding the region of stability of a system

Suppose we have a closed loop system controlled by some microcontroller $K$ First we take the open loop gain which is $\frac{K}{s(s+6)}$.It has 1 pole at the origin and at $s=6$ and 0 zeros. So we ...
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### Max input of a system given it's transfer function and an assumed step change (beginner)

I have an exercise that gives me the following transfer function $$\frac{0.5}{s+0.5}$$ and an assumed step change in the target of 20 I am asked to calculate the maximum input for the assumed step ...
1 vote
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### Controllability matrix is full rank identity matrix

What does it mean, when my system has controllability matrix that is full rank and identity matrix? Having full rank means that the system is controllable, but does the Identity feature of my ...
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1 vote
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### How to implement FLL / carrier recovery? Code and math included

There are lots of options in textbooks, youtube and website blogs. There seems to be three options: Calculate phase difference between samples to infer frequency error or offset. Calculate phase ...
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1 vote
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### How to determine if a system is minimum phase or not?

I'm studying for an exam and this is an old exam question that I don't understand: Is the following system non-minimum phase? $$G(s) = \frac{e^{-2s}}{s+2}$$ I can see that the real part of the pole is ...
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### Implementing digital controller in the time domain

I have simulated a digital control system in the Z domain using MATLAB and I have got satisfactory results. However, when I converted the plant and the digital controller to difference equations and ...
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### Python package to manipulate linear systems

I'm doing some control system work. I was shocked* -- shocked to learn that while Scipy has some nice linear systems classes, they don't extend to computing the cascades or paralleling of two systems....
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1 vote
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### Is it possible to use AMIGO tuning rules with relay control?

I am trying to control a plant with PID using tuning rules such as the Ziegler-Nichols rules. However, it is not always easy just to send a step to your plant source of the image. Another method to ...
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### Intuition for $\mathbf{P} = \mathbf{0}$ in steady-state when $\mathbf{Q} = \mathbf{0}$ (Kalman filter)

Consider the following discrete-time system: $$\mathbf{x}(k+1) = \mathbf{A}_d \mathbf{x}(k) + \mathbf{B}_d \mathbf{u}(k)$$ y(k) = \mathbf{C}_d \mathbf{x}(k)...
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### Confused with special cases of Routh-Hurwitz

When the first column only has a zero we replace is with an $\epsilon$ so we don't divide by zero ahead but divide by the $\epsilon$ then take the limit as it goes to zero. meanwhile if an entire row ...
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### Is there a standardize method for writing statements combinations of (RF) signal flow path through a system?

Let's say I am given a system block diagram of various components that either route/switch/amplify/filter and so on. Each of these components of the system perform these signal modifications or lack ...
1k views

### How do we determine the required sampling rate of a closed loop control system?

Consider the controlled dynamical system $\dot{x}_t = f(x_t, u(t-\tau_{sd}))$, where $0<\tau_{sd}$ denotes the time delay caused by sampling. It is intuitively clear that the time delay caused by ...
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