Questions tagged [control-theory]
The control-theory tag has no usage guidance.
226
questions
-1
votes
1answer
11 views
Nyquist stability criterion for positive feedback
it is known that the stability of a system with negative feedback may be analized through the Nyquist stability criterion, which is based on observing the number of turns around the point (-1;0) in ...
1
vote
0answers
23 views
+50
How do I add unmodeled dynamics to the system?
I am considering the following paper:
Stability‐and performance‐robustness tradeoffs: MIMO mixed‐µ vs complex‐µ design
and I am having troubles understanding how to handle the unmodeled dynamics of ...
1
vote
1answer
35 views
analysis of PD controller vs static-gain
I have a plant $G(s)$ which gives position and velocity as output
$$ G = [G_{ru}(s)\quad G_{vu}(s)]^T $$
where $G_{ru}$ is the integral of $G_{vu}$, and $u$ is the input to the system. Now if I want ...
1
vote
2answers
28 views
How to convert output of controller (control signal) into PWM signal?
I am trying to control a mechanical system with some transfer function T (output is position & input is voltage). I have implemented a state feedback controller in order for the output of the ...
2
votes
0answers
34 views
Finding coefficients for a PID controller that minimize the integral of the squared error (ISE)
The problem
The problem is to find the coefficients for the P, I and D terms of a PID controller used to regulate the object that minimize the the integral of the squared error (ISE):
$$Q = \int_0^\...
1
vote
1answer
79 views
Is it necessary to use PID control in my use case?
I have a workflow of two functions. Both of them aggregate the items that are receiving and only the first is adjustable. I mean that I can decide how many items to aggregate on the first function <...
2
votes
1answer
40 views
what is the physical interpretation of poles and zeros of a mechanical system?
what is the physical interpretation of poles and zeros of a mechanical system?
I'm asking things like the meaning if I have only 0 or only complex numbers. And about the number of the poles and zeros, ...
-1
votes
1answer
46 views
Optimal control vs. nonlinear control
I have tried to compare between two courses, and there seems to be some overlap, but not as much. Which method is better when controlling a nonlinear system? Also, what is the main difference between ...
1
vote
1answer
26 views
Aircraft Longitudinal and Lateral Transfer Function Terms
The figure shows input and output variables for both longitudinal and lateral stability transfer functions.
I completely understand what each term stands for but I was wondering what would be the ...
-1
votes
0answers
11 views
Distributed consensus matrix form , is this form correct?
$\dot \xi = −(L_{n}\otimes I_{m})\xi$
This equation is commonly cited in works about the distributed consensus of cooperative control, in fact, it's the matrix form of the basic consensus algorithm
...
1
vote
1answer
25 views
Doubt on zero pole cancellation
I am looking at a control system which has an unstable pole in the process. The transfer functions of process and controller are the following:
...
1
vote
0answers
35 views
Why a zero too close to the imaginary axis gives bad berformances?
I am studying control systems, and I have found that if I consider I control scheme where I filter the reference , if the zero of the pre-filter is too close to the imaginary axis, we have a ...
-1
votes
1answer
26 views
Predict egg drop outcome in random container
What elements affect the outcome of a raw egg drop in a random container?
I’ve considered friction, mass, size of container, size and type of padding. Are there other elements?
0
votes
0answers
17 views
Complementary sensitivity function in waterbed effect
I am studying the waterbed effect in control systems, and so I have studeird that from the Bode Integral, if I increase the sensitivity to avoid low frequency disturbances, I have amplification of ...
0
votes
1answer
20 views
Control each axis separately - quadcopter
I would like to know why axis can be controlled independently in a quadcopter. I mean, I was told that you can control $x$ and $y$ independently but I couldn't find a demonstration
Edit: the ...
0
votes
1answer
39 views
Limitations on the control effort
I am studying the mixed sensitivity design for control systems, and I have seen that the control effort has limitations given by the bandwidth of the process and by the bandwidth of the sensitivity ...
1
vote
0answers
27 views
Design compensator to improve yaw rate control performance for aircraft
I am trying to design a compensator to improve the yaw rate ($\dot{r}$) control performance of an aircraft. The lateral dynamics for this aircraft is given in steady space form as following:
where A (...
1
vote
0answers
21 views
Control effort in mixed sensitivity design
I am dealing with mixed sensitivity controller design in SISO systems and I am comparing this approch with the classic approch. In particular, I have placed a weight for the sensitivity function in ...
2
votes
1answer
18 views
Stability with eigenvalues' real part equal to zero
I know, from Lyapunov criteria, that a system is stable (not asymptotically) if the system has eigenvalues with negative real part or it has eigenvalues with real part equals to zero, but in this case ...
0
votes
0answers
19 views
Relationship between conjugate poles and resonance peak in frequency response
I have two root locus of two closed loop transfer fuctions, which differ just by a different value of the gain. I have that the one with a larger gain has a reasonance peak bigger in the frequency ...
0
votes
0answers
13 views
Gradient-free optimal control solver?
I have a dynamics simulation that provides the state derivative $\dot x = f(x,u)$, implemented in C.
I'd like to solve the optimal control problem (given an initial state and cost function). Because ...
0
votes
1answer
29 views
Time constant of second order system
I have a second order system with open-loop transfer function
$G(s)={a\over(s+b)(s+c)}$, $a,b,c$ are already known.
This system has unity feedback.
I am interested in the time consant of this system, ...
0
votes
1answer
20 views
Design the equivalent electric circuit (using op-amps) describing open loop transfer function G(s)
How can I convert the Standard form of the second –order system transfer function into op-amp circuit ?
G(s) = wn^2 / (s^2 + 2ζwns + wn^2)
2
votes
0answers
25 views
Problem reading control effort frequency response plot
I am trying to plot the frequency response control effort of a control scheme in Matlab, and in particular I want to do this for different values of tau, which is a constant used to add a pole at high ...
2
votes
1answer
52 views
Problem with performances of a control scheme
I am trying to prove with Matlab that if I have an improper system and I place poles at higher and higher frequencies the performances of the system improves. In particular I am considering the ...
-1
votes
1answer
24 views
Transfer function for a quadcopter with linear velocity inputs
I found the control for a quadcopter using the angular velocities or thrust power as the input, but I need a model where I can set the initial and final position (for example, from (0,0,1) to (0,1,1))....
0
votes
0answers
25 views
H infinity control problem - changing eigenvalues of plant
I'm applying $H_\infty$ approach to control a system with a given input $u$, and I can measure and feedback position and velocity errors. The plant is described by the following transfer function
$$...
2
votes
1answer
37 views
Controls Project: Help needed finding 3rd order system
I'm in need of help finding a third-order or higher system in which I can derive a transfer function. We have a class project in which we need to find a real-life example of the system that equates to ...
1
vote
0answers
19 views
Zero-state observability and strictly passive systems
I'm currently studying passivity theorems of nonlinear systems, and I find it difficult to understand the difference between the different kinds of strict passiveness.
Are there any intuitive ...
0
votes
0answers
28 views
Offline Parameter Estimation for second order system - Ordinary Least Squares
I have a second order system which is described by the following differential equation:
$\ \ddot{y}+α_{1}*\dot{y}=b_{0}*u $
where $\ y $ is the output of the system and $\ u $ is the input of the ...
0
votes
1answer
15 views
Nonlinear behaviour of control plant and adaptive or robust design
In a paper in the context of controller design for DEAP actuators I came upon the following sentence:
Furthermore, the nonlinear behavior of the
control plant requires either an adaptive or a ...
0
votes
1answer
32 views
Adjusting root locus to get a stable system from unstable system
Most of the books that I referred to, used compensators to improve transient performances of a stable system using root locus and compensator design. I got a system which is actually unstable for all ...
1
vote
0answers
23 views
value of $\gamma$ in the H-infinity norm
Suppose I have the system:
$\dot{x} = Ax+Bu$
$y=Cx+Du$
and the following Hamiltonian matrix:
$H=\begin{pmatrix}
A & \frac{1}{2}B^TB\\
-CC^T&-A
\end{pmatrix}$
I want to find the value ...
0
votes
0answers
41 views
effect of coupling in MIMO systems
I have a MIMO system with a 2x2 transfer matrix, for example consider:
$\begin{pmatrix}
\frac{2}{s+1} & \frac{1}{(s+1)(s+2)}\\
\frac{1}{(s+1)(s+2)}&\frac{2}{s+2}
\end{pmatrix}$
I would ...
4
votes
1answer
379 views
Block diagram vs flow chart?
I was studying a book of control system where i read that a block diagram is a specialized high level type of flow chart
So what will be the difference between a normal flow chart and a block diagram?...
1
vote
2answers
51 views
Root locus: ambiguity on which branch goes where?
I could not find a Controls Stackexchange, I hope this is the right place, otherwise I would be glad to post it in the appropriate section. My question concerns the root locus method.
Given a plant ...
0
votes
1answer
43 views
Identification of control system type? Open loop or close loop,
What is the type of control system of door closer in attached photo?
0
votes
0answers
42 views
Adaptive feedforward cancellation (AFC) and least mean squares (LMS) for periodic disturbance cancellation
I already asked this question here, but since I did not get an answer yet I want to try it here as well:
I want to implement an adaptive feedforward cancellation (AFC) for cancellation of the impact ...
-1
votes
1answer
40 views
control systems vs artificial intelligence?(in nut shell for beginners)
i am confused in basic difference between control systems & artificial intelligence? since both techniques can be used for automation
Please kindly try to give answer in nutshell
depth/detail ...
0
votes
0answers
53 views
Maximising the trace of the observability Gramian
Suppose I have a matrix W. This matrix has an observability Gramian Q. Is there a way to see which changes in the matrix W will maximise the trace of Q? Is there a natural way to express maximising Q ...
0
votes
0answers
13 views
What non-Gaussian filter should I use
I am developing a filter to better predict my state of my system. I had previously tried an Extended Kalman Filter. I have all the data needed to predict my next step but I have few observations/...
0
votes
1answer
59 views
Gain and phase margin
Why Bode plots are on jw axis when determining gain and phase margin?
Usually it is explained as 1+G(s)H(s) should not be zero and margins represent how far away from this we are. But for showing this ...
2
votes
0answers
28 views
Meaning of energy method in control theory
What qualifies a energy method in the context of control theory?
Citing from a paper to give the context in which this expression came to my attention:
One of the challenging problems of the double ...
0
votes
0answers
21 views
How does a digital controller's sampling period dictate the system's actuation requirements?
When selecting an actuator for a controls application - e.g. choosing a servo motor for a self-balancing robot - I understand that it's important for the actuators to have fast enough dynamics that ...
2
votes
1answer
64 views
Closed loop guidance and control: how to tune a system with multiple feedback controllers?
I'm trying to design a closed-loop guidance system for rockets - something that can be implemented in Kerbal Space Program, for example. To do this, I'm following the design process described in ...
0
votes
2answers
74 views
What kind of mechanism can be used to rotate a part in 180 degrees (Ψ (yaw)) and 30degrees in 𝜃 (pitch) direction?
Let's say we have a flat object. We are asked to create some mechanism so that the part can rotate in the shown angles above. What mechanisms can be used?
1
vote
1answer
40 views
Designing Block Diagrams For Control Systems
I'm looking for good software to design control systems, and more specifically to neatly design "block diagrams" for control systems.
Is there something like that?
1
vote
1answer
70 views
Changing fields from mathematics to control engineering [closed]
I did my undergraduate in maths and physics and will be working in control theory for my future job. Not to my surprise, my engineering background is rather lacking. I have taken a look at materials ...
1
vote
1answer
50 views
Interpreting Nyquist plot
When implementing the control for my application I got this Nyquist plot which made me flabbergasted.
If I zoom on the point $-1 + 0j$ I get the following image
How do I interpret this contour going ...
0
votes
1answer
136 views
Difference between Hysteresis, low pass filter and deadband in control theory?
I am trying to understand the fundamental difference between the following terms in the context of control systems:
Hysteresis
Low pass filter
Deadband
Are these just fancy names that can be ...
