Questions tagged [control]
The control tag has no usage guidance.
40
questions
1
vote
2answers
47 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 ...
2
votes
1answer
41 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 ...
2
votes
1answer
28 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.
...
0
votes
2answers
48 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 ...
0
votes
0answers
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 ...
0
votes
2answers
49 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 ...
2
votes
1answer
65 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 ...
0
votes
1answer
45 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'....
2
votes
1answer
46 views
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 $K_i$...
1
vote
1answer
40 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 ...
0
votes
0answers
25 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-...
1
vote
0answers
15 views
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 ...
2
votes
1answer
32 views
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. ...
4
votes
2answers
91 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 (...
1
vote
1answer
39 views
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 ...
0
votes
1answer
31 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 ...
3
votes
1answer
83 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, ...
2
votes
1answer
37 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 ...
1
vote
1answer
70 views
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 ...
3
votes
1answer
53 views
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 ...
0
votes
1answer
233 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 ...
3
votes
2answers
278 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 ...
0
votes
1answer
19 views
Understand diagram of a process
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 $z^{-1}$ ?...
0
votes
1answer
324 views
How do I find transfer functions from a state space representation?
Suppose I have a MIMO system in state space representation, for example:
$A=\begin{bmatrix}
1 &2 &3 \\
4&5 &6 \\
7&8 &9
\end{bmatrix}$
$B=\begin{bmatrix}
2 &3 \\ ...
1
vote
0answers
69 views
Influence of a RHP zero/pole in the frequency response
I am studying loop shaping, and I am looking at loop shaping design with unstable poles and zeros. I have seen that noth unstable poles and zeros introduce limitations in the bandwidth. I have also ...
0
votes
1answer
40 views
Doubt on behaviour of frequency responce of a system
I am doing loop shaping using $H_{\infty }$ approch, and I have a plant with an unstable pole:
G = 10/((s+10)*(s-1));
K1 = 4*(s+1)/s;
where G is the plant, and ...
2
votes
1answer
67 views
Doubt on the relationship between the sensitivity and the complementary sensitivity function
I am doing loop shaping with the following transfer functions:
G = 10/((s+10)*(s+1));
K1 = 0.5/s;
where G is the process and K1 is the controller, and If I ...
0
votes
1answer
293 views
How can a stable system have a RHP pole?
I am working with a control system which has an unstable pole in the process. So I have the following transfer functions for the controller and for the process:
...
2
votes
2answers
245 views
Understanding Matlab's Automatic Gain Control function
I am trying to understand the automatic gain control block provided by the communications toolbox. The documentation is here: Documentation
My questions are in regards to two of the configurable ...
0
votes
1answer
258 views
Discretizing a Controller with the Backward Difference Method
In the book "Modern Control Engineering" by Paraskevopoulos it's proved how to discretize a generic controller in the form:
$G(s)=\frac{Y(s)}{U(s)}=\frac{a}{s+a}$
where $a$ is a constant. Done this, ...
0
votes
0answers
34 views
Doubt on inversion of the dynamics
I am studying control system and I have encountered the topic of the inversion of the dynamics. So I have seen that the ideal situation would be
$C(s)=P(s)^{-1}$
but there are some problem with ...
2
votes
1answer
864 views
Lead compensator vs lag compensator?
I already know that lag compensator acts like PI controller and improves steady state and lead compensator acts like PD controller improves transient state but how they achieve their goal? Despite ...
0
votes
1answer
41 views
confusion about poles and zeros of Lead compensator?
I was reading about lead compensator from a website but i am not able to understand how they have extracted zero and pole from transfer function of lead compensator as shown in attached photo?
or ...
13
votes
6answers
3k views
Relation between signal processing and control systems engineering?
Control systems engineering and Digital signal processing are both important courses/subjects of electrical engineering But how these two subjects/courses are related to each other??
Also please ...
1
vote
1answer
3k views
Effect of origin poles on stability?
What will be stability if we have only one single pole at origin in s domain??
and what will be the case for multiple poles at origin in s domain?
1
vote
1answer
80 views
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?
I'm trying to control temperature with PID(Kp,Ki, Kd). During the rise time the system use one PID and when target is reached the system switch to another PID with other parameter in order to ...
0
votes
0answers
40 views
On $H_\infty$ norm for transfer function
For a given scenario in the context of control system, I'm trying to investigate how the $H_\infty$ norm can be calculated for a transfer function as follows:
$$G(s)= \frac{w_n^2}{s^2 +2\zeta w_ns +...
0
votes
1answer
64 views
Calculating an in-loop signal as part of a hierarchical control loop
I've got a control system with two feedback paths, with each path going to a different actuator that corrects the error in the system. One feedback path provides feedback at low frequencies, and the ...
1
vote
1answer
72 views
State space equations
I am stuck on this exercise. I don't know how to deal with this squared y in the denominator. What am I supposed to do to obtain state space equations?
ex.1
Simplified dynamic model of the steel ball ...
0
votes
2answers
65 views
Control optimization problem
I am running into a problem where I have a control system $S[t]$ that takes a control $C[t]$, so that
$$S[t+1] = H(C[t,t-1,...], S[t,t-1,...])$$ the response of the system is the history of controls ...
