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.

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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 ...
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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|...
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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 ...
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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 ...
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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 ...
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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" ...
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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
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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
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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)=...
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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 ...
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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 ...
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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 ...
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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 ...
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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: $$ \...
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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 ...
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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: $$ C(s) = k_p + k_i \frac{1}{s} + k_d \frac{N}{1 + N \frac{1}{s}} $$ ...
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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) ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 &...
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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 ...
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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 ...
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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?
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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 ...
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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 ...
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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 ...
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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
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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
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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?
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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
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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).
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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
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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
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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
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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 ...

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