Questions tagged [control-theory]
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333
questions
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18 views
Is it possible to calculate Over Shoot percentage and settling time of an Underdamped 2nd order system with Ramp input?
Most of the books derive Over Shoot percentage, settling time for 2nd order underdamped it for unit step response. Do these parameters exist for 2nd order underdamped system for Ramp response too?
If ...
1
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1answer
29 views
Excluding the transient in computing RMSE in control algorithm implementation
I have implemented a control algorithm and I would like to study its performance by looking at the trend of the tracking error and then algebraically transpose what I visualize, I have thought to use ...
0
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1answer
35 views
Unstable System. Error Trying to model the Red Bull Stratosphere Free Fall
I tried to model a problem months ago and still I can't solve, I don't want forget this problem so I would like to share what I tried and if you know what is happening with my graph.
This is the ...
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3answers
64 views
If a control system is unstable does it mean it will oscillate?
When a plant is known to be unstable, does it mean it will have an oscillation response?
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30 views
Examples of model-based control techniques
I am trying to find out the differences between the model-based control approach and the data-driven one.
Surely the main difference is the latter's independence from the information of the ...
3
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0answers
36 views
PI or PID-regulator for control system with hysteresis relay in inner loop
I have such control system (sorry for rough drawing :) )
$G(s)$ - stable object with proper transfer function.
$1/s$ - integrator.
I need to clarify, how synthesized PI or PID controller for such ...
2
votes
1answer
32 views
Full state feedback of a closed loop system
Does Full state feedback gains affect the dynamic or steady state gain of a closed loop system?
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0answers
26 views
How do I find the gain from the root locus with given perfomance, where I know the real part of the poles?
I have an exercise to draw a root locus plot and determine its gain to make sure that it fulfills the performance requirements.
the given system G(s) is
$$G(s) = \frac{1}{s^2+s}$$
And the given ...
0
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1answer
39 views
Quality of the transient response for an arbitrary transfer function
The question is simple and I rather need a reference point.
How the parameters of transients are estimated (as in the picture) from an arbitrary linear transfer function (formula is given).
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2answers
69 views
Why prefer a discrete-time system because of a practical implementation instead of continuous one
I have previously done this question on math stack, and I think that maybe here is better.
I am studying the theory of discrete-time systems, comparing them with continuous ones in the control theory ...
2
votes
2answers
282 views
How are bode plots drawn for unstable systems with time delay?
All the example of bode plots I see in textbooks are of stable systems without delay. I wanted to know if bode plots can be drawn for unstable systems with time delay.
Using the usual method to draw ...
3
votes
1answer
71 views
Modelling of Ball and Beam System
I'm trying to model a basic ball and beam system using Euler-Lagrange Equation. My system looks something like this
I have come up with this final Euler-Lagrange Equation:
Where JB is the ball's ...
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0answers
33 views
Phase margin by definition
I'm reading about Gain Margin and Phase Margin in a book and having trouble understanding why they calculate the Phase margin like this:
<G(Wcrossover) - (-180) = PM
Why not: <G(Wcrossover) - (...
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2answers
50 views
How to simulate open and close and control valve using a simple controller
I have successfully developed a mathematical model for my physical system. My objective is to control the mass of gas in and out of the system.
The mass flowrate is given by:
$V_f = C_d.\sqrt{2.\frac{\...
2
votes
1answer
66 views
How do I study the frequency response of a physical system with Arduino?
I am a control engineering student and I am studying the frequency response of a system, so the Laplace domain, the Bode plot, poles, zeros,etc. ...
I have clear grasp of their meaning, but if I think ...
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1answer
38 views
What is the meaning of this symbol in Control System Diagram
I was reading the paper "Full-Speed Range Self-Balancing Electric Motorcycles Without the Handlebar" released in March 2016 by Professor Yang and Murakami in Keio University.
I couldn't ...
0
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0answers
34 views
Issue with LQR Q matrix for a cart-pendulum model
I am currently trying to develop a controller using LQR for a Segway. The model that I am using is an inverted pendulum on a massless cart. I have made animations of the uncontrolled pendulum and of ...
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0answers
40 views
Demonstration of Controlability and Observability
After I studied my Control Engineering courses some years ago, although I was able to interpret the results obtained after calculating the observability and controllability, I haven't been able to ...
1
vote
1answer
60 views
Can fullstate feedback control reject a disturbance?
Compare to PID. The part that rejects disturbance is the I-term which integrated from error signal. On the other hand, in full state feedback there are no integral part. How does it reject the ...
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0answers
35 views
Robustness to Additive Uncertainty Proof using small gain theorem
I am trying to use the small-gain theorem to prove the robust stability condition for additive uncertainty. I have been stuck on it for a while now.
Question: How can I use the small-gain theorem to ...
2
votes
1answer
33 views
Applying PSO for tuning a compensator for double integrator plant
I was reading a book on control systems by Richard Dorf and he lists procedure for designing a lead compensator for a double integrator plant. Using the method I developed models in Matlab and it ...
0
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2answers
54 views
Do I need a feedback loop while testing PID controller?
This is a homework for my university course control theory.
The task is simple: Test the P, the I and the D controllers separately to see the effect.
We don't have to connect the controllers to a ...
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0answers
41 views
State space representation of a product of transfer functions?
In short, I suppose the question boils down to: If we are asked to find the state space representation of $C(s) \cdot G(s)$, where C(s) and G(s) are both transfer functions, then do we treat them as ...
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0answers
42 views
Controller to maintain a stable amplitude
I am recording a channel before and after injecting current into that channel. I control the current injection using a switch, when the switch is on current goes to the channel, when the switch is off ...
1
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0answers
23 views
Increasing convergence rate using Optimal Control and Pontryagin Maximum Principle
My question is in addition to Tuning the optimal control synthesized according to the Pontryagin maximum/minimum principle and choosing the cost function, but requires help from the mathematical side ...
0
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0answers
32 views
steady state errors of a control system
I was reading that for a type-2 system the value of acceleration constant
$$K_a = \omega^2$$ where $\omega$ is the gain cross over frequency. This means that the units for $K_a$ should be $(\frac{rad}{...
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0answers
18 views
Control Partitioning in presence of external disturbance force
I am simulating the dynamics of a control system that has been designed using the control partitioning technique (model-based control + servo control).
I am having a query for the case when an ...
1
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0answers
21 views
Find same modulus z plane poles of over damped system
I am asked to find two poles of a second order discrete over damped system that have the same magnitude (0.4, to be exact) in the Z plane. From what I understand, that is not possible since over ...
0
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1answer
51 views
Input signal rescaling block [closed]
The input signal is limited and lies in range $[-U;+U]$. $U$ - unknown.
The output signal must be rescaled to be in the range $[-1;+1]$, i.e. is $+1$ if the input is at steady-state $+U$, and $-1$ if ...
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0answers
47 views
Nonlinear system with time-optimal control
Given nonlinear system:
\begin{cases} \dot{x_1}=x_3+u \\ \dot{x_2}=-x_2+\dot{f} \\ \dot{x_3}=-x_3+x_2 \cdot \alpha \sin(\omega t) \\ \dot{x_4}=-x_4+x_2 \cdot (\frac{16}{\alpha^2}(\sin(\omega t)-\frac{...
0
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2answers
57 views
Why shooting precision improves using two hands in opposing directions?
I wonder if someone knows a control theory model that explains the reason why using our two hands (typically in opposing directions) improves gun shooting precision. A similar situation seems to ...
0
votes
1answer
36 views
Zero overshoot criterion from the initial point $x_0$ to the final $x_*$, $x_*$ unknown in advance
Suppose a system is described by the following ODE:
$$\dot{x} = f(t,x)+u$$
where
$x$ denotes the state of the system
$f(x,t)$ is an unknown nonlinear function which meets the following condition:
$$ ...
0
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0answers
22 views
Mixed Sensitivity Problem
I have plant,
$$P(s) = \frac{1-s/5}{(s^2 + s/4 +1/4)}$$
I am taking a mixed sensitivity approach for that I have chosen $V$,$W_1$ and $W_2$ as follows:
For bandwidth, $\omega$ =1 so I chose M as,
$M = ...
1
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0answers
40 views
LQR control effort / control bandwidth relationship
I'm working with a linear system, having given matrices A and B
$$A = \left[\begin{array}{cc} 0 & 1 \\ -0.9 & 0 \end{array}\right]$$
$$B = \left[\begin{array}{c} 0 \\ 2 \end{array}\right]$$
...
2
votes
2answers
199 views
How do I interpret the following Bode, Nyquist and Nichols diagrams?
I am working with an arbitrarily complicated and long-winded transfer function that looks something like this:
$$
H(s) = \frac{as^4+\cdots+b}{cs^6+\cdots+ds^2}
$$
where letters represent constants. ...
0
votes
1answer
61 views
Examples of situations where using classical control methods are better than modern methods
I'm doing some reading on control systems at the moment and when reading pages on classical control methods, some sites state that they are preferred in industrial applications.
I've read that simple ...
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0answers
32 views
Finding Derivative Gain for PD Controller
I am trying to design a PD controller $G_c(s) = K_d(s+z_c)$ with the following requirements:
No overshoot, $\zeta = 1$
Settling time $T_s = 0.0002s$
The transfer function that I am currently working ...
0
votes
1answer
30 views
why do we need state feedback in H-infinity concept instead of output feedback
I have faced control of a flexible manipulator which have a zero dynamic related to flexible parts dynamic. the zero dynamic states (generalized states) are not observable in input-output dynamic and ...
0
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0answers
19 views
Scalability in the context of optimization and control systems
I am having a hard time trying to make sense of the phrase "Scalable optimization". I read from a few papers discussing that some global optimization solvers like BARON, ANTIGONE, etc. do ...
0
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1answer
76 views
Stability of a closed loop control system
I have a question regarding control theory. Say I have a closed loop feedback system and I have found the closed loop transfer function, how would I then assess the stability of my closed loop system ?...
2
votes
1answer
63 views
Is it possible to solely use a P-controller for velocity control?
Let's say I want a robot to run at a certain speed. I have one motor attached to each robot rear wheel. The feedback value to the controller comes from an encoder, which outputs pulses per time unit, ...
0
votes
1answer
46 views
Determine Stiffness (k) and Mass (m) of a system from impulse response
I have a test sample (Piezo Diaphragm) which I am actuating with a voltage supplied to the sample to assess the impulse response.
When this voltage is supplied to the sample a deformation per unit ...
0
votes
1answer
46 views
How to model this real-world system to define transfer function for stability?
The system shown is an off-axis drive system that rotates the platform to 60° via a substantially-sized NEMA 34 stepper motor. The axial force required by the stepper/ballscrew assembly has already ...
0
votes
1answer
30 views
Transfer Function
Hi Guys I am trying to evaluate the following transfer function below can anyone verify if this is correct
$$e_i = -d_{r,i} + d_i $$
$$d_i = q_{i-1}-q_i$$
$$d_{r,i} =H_iq_i$$
$$Therefore, e_i = -...
0
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1answer
46 views
Closed Loop transfer Function
Hi Guys wanted some help for breaking down a block diagram which can be seen below. I know that typically with feedback systems be it negative or positive you would employ using the following:-
Close ...
0
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1answer
220 views
Determine the parameters for this given nyquist plot
I have seen quite many of this type of question and I want to find how to solve them but I haven't cracked it yet. For example this is one:
My thoughts so far:
Replace $$s \rightarrow j\omega$$, $$G(...
0
votes
1answer
50 views
Which way of solving from nonlinear control to choose?
I have a nonlinear system:
\begin{cases} x'=f(x)+u \\ y=f(x) \end{cases}
where $f(x)$ - gradient of some one-extremal function (for example $f=e^{-(x)^2}$), i.e. $\frac{df}{dx}$.
Task:
I want ...
2
votes
2answers
116 views
Why does accuracy of temperature PID controller drop over time and how to eliminate it?
What am I trying to control?
I have a container with approximately 3*2*6 meters (width, height, length).
I am controlling through PID the ...
1
vote
2answers
63 views
High pass filter and differential equation relationship
Consider the problem stated as follows:
A signal y passes through a high pass filter $\frac{s}{s + ω }$. A high pass filter with cutoff frequency ω isolates the variations of this optimized variable ...
1
vote
4answers
92 views
PID controller - Counterproductive derivative
I'm having trouble understanding the derivative part of a PID controller, because it sometimes seems to react the opposite way that I would like.
Let's use a simple example where :
the controlled ...
