9
votes
Accepted
Is $y[k] = y[k-1] + x[k]$ an integrator?
The system
$$y[n]=y[n-1]+x[n]\tag{1}$$
is an ideal accumulator, i.e., it computes the cumulative sum of the input samples:
$$y[n]=\sum_{k=-\infty}^nx[k]\tag{2}$$
It is in a way analogous to a ...
- 80.2k
8
votes
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Real time numerical differentiation of signals
Your original differentiator, which should be $x(n)-x(n-1)$, is called a "first difference" differentiator. That differentiator amplifies high-frequency noise. As a next step I suggest you try what's ...
- 4,818
6
votes
Is $y[k] = y[k-1] + x[k]$ an integrator?
Your simple integrator is called a "Rectangular Rule" integrator. There are more complicated (and more accurate) integrators called "Trapazoidal Rule", "Simpson's Rule", and "Tick's Rule" integrators.
- 4,818
5
votes
How can I experimentally find the bandwidth of my PLL?
A step response test is an easy way to determine the bandwidth. Sum a small step into the control voltage of your oscillator (VCO or NCO), and measure the 90% to 10% fall time of the corrected ...
- 37.1k
5
votes
Real time numerical differentiation of signals
In a 2003 paper in French, "Estimation par maximum de vraisemblance de la dérivée d’un signal bruité. Application à la caractérisation de vérins pneumatiques" (Maximum likelihood estimation of the ...
- 29.9k
4
votes
How to set parameters of the PI controller inside the PLL?
Two suggestions to move forward:
Reduce $K_i$ to the point of an acceptable overshoot (this will provide the bottom line answer for comparison to the computations.
Do system identification (Bode ...
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3
votes
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How to design a Controller that would adjust the steady-state error of a system?
I'm not gonna give you a complete answer but I can help you.
Your open-loop transfer function has 2 poles at $ -1 ±j \sqrt(3) $
Good news, they are stable. However, they are not damped and they are ...
- 3,560
3
votes
What is the difference between a controller and a compensator?
As the book's title is control theory; a controller is the general broad name given to any piece of hardware (or sowftware) that aims to control some processes, in your aerodynamics field probably the ...
- 26.7k
3
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What is the difference between a lag compensation and PI control?
Well, the two systems differ only at low frequencies. In fact, if you define
$$
R_L = \dfrac{\tau_zs+1}{\tau_ps+1},\qquad R_I = \dfrac{\tau_zs+1}{\tau_ps}
$$
you have that $R_I(j\omega)\underset{\...
- 738
2
votes
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A PID that can handle 2 inputs for my application
If you require two outputs, which belong to a movement in x and the other in y direction, you could start with the assumption, that both movements are independent an simply implement two PID ...
- 112
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Is a good practice to use one PID in rise time and another PID for steady time in order to eliminate oscillations during steady time?
Switching between 2 PID controller is called gain-scheduling. There are various ways to implement gain scheduling. But basically, the idea is that the gain should change smoothly. You should not ...
- 3,560
2
votes
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PID and convolution
Considering the Laplace transform of a function $x(t)$ as :
$$X(s) = \mathcal{L}\{x(t)\} = \int_{-\infty}^{\infty} x(t) e^{-st} dt \tag{0}$$
then to find the following Laplace transform
$$\mathcal{L} \...
- 26.7k
2
votes
How to set parameters of the PI controller inside the PLL?
1 There's a mistake in the PID connection. You must feed the quadrature component, i.e $U_q$ to the PID, not $U_d$. The setpoint of your PLL is $U_q = 0$ because you want your PLL to be in phase with ...
- 3,560
2
votes
How can I experimentally find the bandwidth of my PLL?
This is just a different flavor of what Dan Boschen suggests. In fact, the actual summing junction part is exactly what he's suggesting.
Insert a summing junction, and then inject a signal ($u_A$ in ...
- 8,240
2
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Why is the close looped model under control called plant?
I have heard that the word comes from "plant" as in "steam plant". But I don't know of any historical research that's been done to pin down the term.
I did just check my copy of &...
- 8,240
1
vote
Accepted
Discrete implementation of the PI controller
Define "appropriate".
Yes, the output of the controller will be limited to between your action_max and action_min -- ...
- 8,240
1
vote
How to deal with "weird" phase plots in bode diagram when designing a controller
Following your edit, the first challenge in creating a controller is the task to create a stabilizing controller. After that, performance can be tuned. In order to find if the created controller ...
- 186
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vote
How to deal with "weird" phase plots in bode diagram when designing a controller
I'm a bit puzzled with your Bode plot, here's what I get with your transfer function and Matlab 2019b. My phase starts at almost -180 degrees while yours start at 0 degree. Is it possible that you've ...
- 3,560
1
vote
Tuning a PID Controller
You have 2 right-half plane zeroes : 0.012 and 18. The zero at +18 is "fast" and will not affect the performance much, but your slow zero at 0.012 will severely limit your performance. You ...
- 3,560
1
vote
Why is the close looped model under control called plant?
"Plant" doesn't only refer to the living thing that has chlorophyll; it, in the context of control, refers to a technical system with in and output – some production line, a whole factory, a nuclear ...
- 26.1k
1
vote
Drift in PID controller
Your controller controls pitch and roll. However, in the graph you showed us we only see x,y and z.
Could you add the plot for pitch and roll? I'm not an expert in aircraft control, but I think you ...
- 3,560
1
vote
Accepted
How to approximate the transfer function of compensator using root locus?
K is the gain parameter for which you will be at any particular point on the root locus. As you increase K, the closed loop poles will start from the open loop poles and move toward the open-loop ...
- 37.1k
1
vote
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What is the difference between a controller and a compensator?
The objective of a controller is to respond to the error, an example of a controller is the PID.
On the other hand the objective of a compensator is to change the original dynamics of the plant, ...
- 54
1
vote
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General tips for PID tuning of super low-friction actuator?
1 - Do you have some general idea of what your transfer function looks like? Or at least a frequency response? Could you perform some kind of step response? You could then try to fit an order-2 model ...
- 3,560
1
vote
Accepted
Oversampling while maintaining noise PSD
One important point you may be missing is assuming that the noise of the ADC is truly white over your sampling bandwidth- it isn't! You will have spurs from signal correlations and ADC non-linearities ...
- 37.1k
1
vote
Accepted
Does a PID need to be "online" to be tested? Can the output signal be viewed without it being used?
The PID can be tested in an open-loop setup, however any integral gain <> 0 will cause the PID output to run away, so you are likely to hit clamping (like control voltage maxima) with your test rig....
- 146
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vote
Is $y[k] = y[k-1] + x[k]$ an integrator?
Yes, the system should be an integrator.
What method did you use in the call to d2c.
- 22.4k
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