Questions tagged [control-engineering]
Questions about the models and theories of control engineering and the application of control theory to design systems with desired behaviors.
617
questions
7
votes
4answers
1k views
Why are train brakes so complicated?
The concept is simple enough: no pressure in the train line has the brakes locked, full pressure is loose, and partial pressure drags accordingly. So if pressure is lost for any reason, the train ...
0
votes
1answer
46 views
Definition of Bandwidth as angular frequency
I am searching for a Formal Definition of bandwidth given the transfer function of a system, or the bode plot.
Is it the frequency $\omega_b$ in which
$$20log|H(j\omega_b)| = -3\text{dB}$$
or
$$20log|...
0
votes
0answers
30 views
Double Summation of Matrices in Convex Optimization in CVX
I want to implement the following optimization problem from the following paper Randomized Gossip Algorithms, Page 10 Eq. 53\
1- In this problem, $W$, $P$, and $P_{ij}$ are $n\times{n}$ matrices. I ...
0
votes
1answer
37 views
Control Systems: 3rd order system project [duplicate]
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 ...
0
votes
1answer
42 views
How to model a cable for control?
I'm studying a system in space that uses centrifugal force to keep four tip masses extended. The system is defined as follows : a central hub that has rotation freedom in all directions, four tip ...
0
votes
1answer
30 views
Simulink Treating Discrete-Time State-Space as Continuous-Time?
I have a MATLAB script wherein I take a second-order ODE on $\mathbb{R}^3$ (vector field on the phase space), then, at a critical point, take the Jacobian matrix $A$, use a "fully-actuated" ...
0
votes
2answers
42 views
What is a "Unidirectional Input" (?) Closed Loop Control Algorithm Called and How Does it Work?
PID systems inherently require some amount of overshoot in order to stabilize around a target. This often requires adding or subtracting some resultant term in order to shrink the relative error. ...
2
votes
0answers
33 views
Relationship between the infinity norm of estimation error and the trace of estimation error covariance matrix in Kalman filter
I am working on designing an interconnected distributed control system. In this system, I need to use Kalman filter because the measurements are noisy.
I have two questions:
1 - What is the ...
0
votes
0answers
22 views
Best Techniques to design a cascaded precision position controller
I'm looking to design a cascaded controller to transform a BLDC into a servomotor. The system has a motor current controller in the inner loop, which is controlled by a torque controller, which is ...
2
votes
0answers
37 views
How do you generate an impulse signal in a mechatronic system?
Background:
I have a piezoelectric force transducer that I am using to measure the force produced by a combustion reaction in a tube. The issue is that there is a lot of ringing that occurs during the ...
0
votes
1answer
46 views
What are disadvantages if increasing the gain Kd for a PD(Proportional Plus Derivative ) controller
What are disadvantages if I increase the gain Kd for a PD(Proportional Plus Derivative) controller, someone told me larger gain for derivative error for will reduce the stability margin, while the ...
3
votes
2answers
67 views
Why do pneumatic valves need both a Safety Relay and an Air Dump to be safe?
If air dumps safely release pneumatic pressure from an industrial machine when an E-Stop is pressed, why is it also standard practice to cut electrical control power from the valves with a safety ...
0
votes
1answer
43 views
How could I compute the stability margin from a closed loop response?
Why the stability margin is typically computed by the open loop response or transfer function rather than the closed loop response or transfer function, how could I measure/compute the stability ...
0
votes
0answers
36 views
Transfer Function for Electro-Mechanical System
Can anyone please lead me in the right direction as to how to solve for the transfer function given this motor schematic
0
votes
0answers
35 views
Additive perturbation
consider the following transfer functions:
$$
G(s)=\frac{1}{\tau s+1}G_0 \quad \tau_{min}<\tau<\tau_{max}
$$
show that this system equal to model with additive perturbation as follow
$$
G(s)=...
0
votes
0answers
30 views
Limitations to consider when picking a cut-off frequency low-pass filter for PID control?
Considering a first-order low-pass filter transfer function:
$$ \frac{\omega_c}{s + \omega_c} $$
Where $\omega_c$ is the cut-off frequency. Are there any limitations on where to place this pole?
For ...
0
votes
3answers
57 views
Question about how to study for engineering university exams [closed]
What are some of the ways to predict exam questions from class lectures in university final exams? How should one understand the mindset of the professor & find out important maths/questions he ...
0
votes
0answers
34 views
Time Constant For Step Response First Order System
I ran several experiments where I attached my phone to a motor and collected the angular velocity at different step inputs( different voltage values). My question is, is it possible for the motors to ...
0
votes
0answers
30 views
Block-diagram combining two controlled subsystems
I have two subsystems which are shown in the picture below.
One of them is a system of stable and controlled differential equations of a mechanical system.
Second is a block that implements a function ...
0
votes
0answers
22 views
plotting time delay system eigenvalues
I want to plot eigenvalues of below time-delay system in MATLAB
$$\dot x(t)= x(t)-a x(t-T)$$
T is delay
what I did until now is first I find the constitutive equation of this system as follow:
$$
\...
0
votes
0answers
37 views
Linearizing nonlinear system for PID control
I have a system where y = 1/x. (y=output, x=input)
If I calculate the PID error not by reading y, but by reading 1/y (so linearizing the system), will my system be nicely linearized, and the PID ...
1
vote
0answers
37 views
(Dominant) Poles very close to zeros in PID control
I have a plant transfer function $G(s)$:
$$ G(s) = \frac{1}{s^2(0.1s + 1) } $$
I want to control this with practical PID control:
$$ C(s) = k_p + k_i \frac{1}{s} + k_d \frac{N}{1 + N \frac{1}{s}} $$
...
0
votes
2answers
69 views
How to tune a PID controller when plant's step response looks like a ramp?
The system is a boat and I want to specify a yaw angle and the PID controller would operate the rudder of the boat in order to reach the desired yaw angle. So, the step response of the plant (boat) ...
0
votes
0answers
28 views
What is residual oscillation and critically damped oscillation in the context of a controller's performance?
What do these terminology "residual oscillation" and "critically damped oscillation" mean when evaluate a controller's performance? How are they related to the stability of the ...
0
votes
0answers
25 views
How to determine time constant/cutoff frequency of the filters in the controlled loop
I was told to be careful to use filters in the control loops as it will add extra time delays in the system and degrade the system dynamic response, but I also saw there are lots of filters in ...
1
vote
2answers
59 views
How could I verify the stability of a real system with non-linearities?
For a closed loop system, I could do the stability margin analysis using linear method like bode diagram, but in reality there are non-linear elements in the system like saturation/rate limits inside ...
1
vote
2answers
37 views
Control System Response
How does one find the zeta value or the frequency of an over damped response curve. I am used to determining things by using the log-decrement equation. Does that apply here even though there is no ...
0
votes
1answer
51 views
Could someone explain how a compensator shifts the root locus?
I'm reading a root-locus course note from MIT. However, I can't understand this part:
How does adding a compensator with a pole at origin remove the plant pole on the right half-plane into the left ...
0
votes
1answer
66 views
Drawing nyquist diagram by hand for a system with time delay
how can I draw the Nyquist diagram of Kexp(-Ts)/(s*(s^2+s+a) by hand for different a and K values and examine the stability of the system depending on T value? I drew for the case with no time delay ...
1
vote
0answers
34 views
Sliding-mode control is a model-based technique?
The sliding mode control can be considered a model-based control? In my opinion yes since takes the information of the mathematical model of the system to be controlled handling with possible ...
0
votes
1answer
61 views
Controls System experiment
We performed an experiment in which we turned a bicycle on its side and placed a piece of green tap on one of the spokes. We spun the wheel and recorded the wheel spinning until it came to a complete ...
1
vote
1answer
52 views
Can I design/tune the outer loop controller without knowing the details of the inner loop controller?
In cascade PID control loops as below, can I make an assumption that the inner loop will respond much faster than the outer loop, hence I could simplify U1_CMD as U1 and I could design/tune the gains ...
1
vote
0answers
28 views
What is the original paper using Extended Kalman Filter for joint state and parameter estimation [closed]
The title says it all.
I would like to know which was the first paper to apply the Extended Kalman Filter to jointly estimate the state plus some parameter of the system.
(by extending the system ...
0
votes
0answers
41 views
Stability from Gain and Phase Margin
I know that a system with positive gain and phase margin is a stable system. And the one with a negative gain and phase margin is unstable. What will a system with negative phase margin and positive ...
1
vote
1answer
57 views
Is It Possible to Have a Continuous-Time System Controllable but Discrete-Time System Uncontrollable?
I have a continuous-time state-space system $\dot{x} = Ax + Bu$ with
$A = \begin{bmatrix}0 & 0 & 0 & 1.0000 & 0 & 0\\
0 & 0 & 0 & 0 & 1.0000 & 0 \\
0 & 0 &...
0
votes
0answers
20 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
vote
1answer
33 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 ...
1
vote
3answers
175 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?
0
votes
0answers
36 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 ...
0
votes
1answer
62 views
Why matlab returns a damp ratio as 1 for a over damped system?
I have a second order system with the transfer function as: "1/(s^2 + 5.45s + 1)", I thought it should be an over-damped system, but when I use the damp function in MatLab, it returns the ...
0
votes
1answer
39 views
Nominal model and Mathematical model of a real plant [closed]
What is the difference between nominal model and mathematical model of a real plant?
I am interested in understanding the difference since I want to understand why in some cases is not the best idea ...
0
votes
2answers
30 views
Force control of pneumatic piston
I am building a small testing device consisting of a double acting pneumatic cylinder. I am using an existing pneumatic line running at 100 psi and I would like to control the force exerted by the ...
3
votes
0answers
48 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
40 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?
0
votes
0answers
31 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
votes
1answer
47 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).
0
votes
2answers
87 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 ...
1
vote
1answer
67 views
LQR control of motor speed for a quadrotor
Im working around with a simulation of a quadrotor.
So i've read articles, did the math to derive the set of equation using lagrangian approach. So far so good.
Then i want to control the system. so i ...
0
votes
2answers
114 views
Aluminum or Copper, which one is better to control and maintain the temperature?
Friends, I am an EE/SW/Controls eng. Please, pardon me of perhaps incorrect terminologies.
I am working on a R&D project: A chemical lab equipment has a 2" long metal pipe enclosed in ...
2
votes
2answers
297 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 ...
