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.

Filter by
Sorted by
Tagged with
1 vote
1 answer
61 views

Linearization about equilibrium point 0 in the presence of unknown input

Consider a SISO non-linear system $$\dot{x} = F(x,u)$$ in which $\vec{0}$ is an equilibrium point. In the process of determining that it is indeed an equilibrium point, the input did not matter at all....
user avatar
-1 votes
0 answers
26 views

Phase shift in Fourier transform

Suppose we have a signal x(t). If we Fourier transform the signal to the frequency domain we get a complex function (has js in it). Do the js mean a phase shift and what does phase shift in a Fourier ...
user avatar
0 votes
0 answers
14 views

Fourier analysis of delta function

I have this periodic function: $f(t) =\delta(t)+ \sum_{n=1}^{\infty }\delta (t-n)+\delta (t+n)$ and I need to find its harmonics by finding the coefficients for the Fourier series. But how is this ...
user avatar
1 vote
1 answer
48 views

Control Engineering: Formal vs. Trial-and-Error

At university, my control engineering courses are focused on a more theoretical approach, but the main message from our professors was clear: When designing a feedback controller (PID, H-infinity, MPC,...
user avatar
0 votes
1 answer
55 views

Which controller is more suitable in this scenario? P, I or PI controller?

Scenario: A robot has a ultrasonic sensor which measures the distance to the nearest object in centimetres. The robot has two motors, a motor for the left wheels and a motor for the right wheels. The ...
user avatar
0 votes
1 answer
33 views

How to determine the components of a feedback control loop given following context?

Based on this feedback control loop where $w$ is the desired setpoint, $x$ the process variable, $e$ the error value, $y$ the correcting value and $z$ the disturbance value. Did I interpret the ...
user avatar
0 votes
1 answer
61 views

Measure a frequency response function

I have a slide here which says following: For the control loop ...apply $d$, measure $u$ and $y$, calculate $\hat{H}(f) = \frac{S_{yu}(f)}{S_{uu}(f)}$ but then typically $E\{\hat{H}(f)\} \ne H(f)$ ...
user avatar
0 votes
0 answers
36 views

Do asperity junctions break every time a machine starts to rotate?

After reading CONTROL OF MACHINES WITH FRICTION by Brian Armstrong-Helouvry, some questions rised. The main question I ask you is: Suppose two metal surfaces in relative motion first in static ...
user avatar
0 votes
0 answers
24 views

deal with algebraic loop in distributed control algorithm

Recently I found a distributed control method for multi-agent system, which implements an algebraic loop like: $$ u_{i}=(l_{ii}+b_{i})^{-1}\left [{\sum _{j\neq i}a_{ij}u_{j} -\mu e_{2i}+b_{i} u_{0} }\...
user avatar
0 votes
0 answers
60 views

How can I find characteristic equation of complex systems?

I am working on an Overhead crane, where I am supposed to design a controller that controls the position of the crane while minimizing the load's sway angle. I have derived the transfer functions for ...
user avatar
0 votes
1 answer
41 views

Contradiction of bandwidth and damping

I am studying control theory and mechanical vibrations. From control theory aspect, I know that bandwidth and response time is inversely proportional, which means bandwidth and damping as well. But in ...
user avatar
  • 1
0 votes
0 answers
40 views

How does adding a long fixed pole on top of a drone with a certain mass change the dynamics of a quadcopter?

I have to model a quadcopter with a long rod on top of it so I can later design a control system for the system. I'm a bit lost as to how the dynamics of the system change by adding the rod, can ...
user avatar
1 vote
0 answers
28 views

What's a real life example of linearization of a system around a fixed point

I'm tasked on finding a example of a real non-linear control system. a real paper or publication on a website like the IEEE thats describes the model of the system so I can then linearizy it around a ...
user avatar
0 votes
1 answer
50 views

Bode plot phase margin concept details

I know a closed-loop system $\frac{G}{1+G}$ is unstable when the open-loop transfer function $G$ equals -1 or $0dB\angle-180^{\circ}$. The denominator becomes 0 so the gain is infinite. This is why ...
user avatar
  • 1
0 votes
0 answers
32 views

Phase margin concept: why can there be instability when the gain never reaches 0dB?

If the open-loop transfer function is always below 0dB but the phase crosses or approaches 180 degrees, the closed-loop system can still be unstable. Why? Example: open-loop transfer function $\frac{0....
user avatar
  • 1
0 votes
0 answers
16 views

SMC: Is there a way to control two sliding surfaces with just one control input?

This is a question related to Control Systems. I've been searching papers all over the internet with very little success. I know that traditionally we want one control per sliding surface but If ...
user avatar
  • 103
1 vote
3 answers
52 views

How can nuclear reactors control the exponential cascade of neutrons fast enough to prevent an explosion?

The Wiki article on nuclear reactor physics states that the average neutron lifetime in a typical core is on the order of a millisecond, the exponential factor is as small as 0.01, in one second the ...
user avatar
  • 131
0 votes
1 answer
45 views

Steady state error of negative feedback system - zeroes of feedback function

I am currently studying control systems from the KUO - GOLNARAGHI book. Regarding the steady state error the book makes the following distinction: Feedback function H(s) has no zero at s = 0 Feedback ...
user avatar
0 votes
1 answer
26 views

Can I drive a pulley with two shaded pole motors using one motor at a time with different size pulleys for speed control?

Using two same RPM shaded pole motors, one with a one inch diameter motor and one with a two inch diameter. Using a DTDP switch to swap power from one pulley to the other. For a two speed rotation ...
user avatar
0 votes
0 answers
28 views

Control strategy for upper/lower limit control

I am currently facing a problem, for which I cannot find a decent control strategy. The problem is that I want to limit an observable/measurable variable in its maximum and minimum. As an example I ...
user avatar
  • 1
0 votes
0 answers
34 views

How to control speed of DC Gearmotor with Varying Torque

I have a system where the torque is constantly changing, but I need the speed to remain at 9RPM. I have enough room for error where I can be between 8 and 10RPM. How can I achieve this? All I can find ...
user avatar
0 votes
0 answers
30 views

Modelling an S-shaped Second Order Process Response

I am trying to model an S-shaped second order process response as a transfer function in Simulink, as shown in figure 3 in the linked article. Ideally the response should be overdamped. I have tried ...
user avatar
0 votes
2 answers
67 views

Modeling a second order system in time and frequency domain

For school I was asked to model the transfer function $H(s)=\frac{3}{(s+4)(s+5)}$ in both the time and frequency domains using initial conditions $y(0)=2,y'(0)=3$, a step input, and Simulink. I would ...
user avatar
  • 3
0 votes
1 answer
67 views

Unexpected uncontrollable double integrator system during reference tracking (augmented state-space)

I'm trying to design a controller that will achieve reference tracking of the second state for the following system. $$ \begin{aligned} \dot{x} &=\underbrace{\left[\begin{array}{ll} 0 & 1 \\ 0 ...
user avatar
0 votes
1 answer
38 views

Stability properties of controllers with independent control laws applied in underactuated systems

I am interested in designing a GNC controller for a 3DOF underactuated vehicle that follows a path in 2D space. The two available control inputs are the thrust force in the surge direction and a ...
user avatar
  • 1
0 votes
1 answer
130 views

How to model the state space matrix of a pendulum?

Here's an image of the problem: I'm trying to put the following problem in matrix form (state space) but I don't know how would I put -(g/L)sin(x1) in the A matrix since the x1 value is inside the ...
user avatar
  • 103
0 votes
1 answer
122 views

Dynamical system problem

I have this dynamical system: A = [ -0.313 56.7 0 -0.0139 -0.426 0 0 56.7 0]; B = [0.232 0.0203 0 ]; C = [0 0 1]; D = 0; I'm ...
user avatar
  • 5
0 votes
1 answer
33 views

Motor that plugs directly into wall outlet

I am looking to drive a disk at relatively low speeds (9rpm) and somewhat high torque (not sure on exact numbers, 100+ in-lb.) I am looking for a motor that can plug directly into the wall and just ...
user avatar
0 votes
0 answers
44 views

Finding optimal PID gain values with no Transfer Function or Plant model

Background: I have a Matlab simulation model with .m files. The functions simulate a speed control system of a vehicle. I can control the vehicle's speed by adjusting the vehicle’s acceleration and ...
user avatar
0 votes
0 answers
36 views

Control scheme for roll compensation

I'm working on an application that rotates a cylindrical mass in a manner to compensate for roll in a boat. The roll of the boat is rather slow so I was thinking it might be possibly to simply use a ...
user avatar
  • 1
17 votes
4 answers
5k 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 ...
user avatar
  • 561
0 votes
1 answer
79 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|...
user avatar
0 votes
0 answers
37 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 ...
user avatar
0 votes
1 answer
103 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 ...
user avatar
  • 1
0 votes
1 answer
46 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 ...
user avatar
  • 121
0 votes
1 answer
103 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" ...
user avatar
0 votes
2 answers
49 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. ...
user avatar
2 votes
0 answers
36 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 ...
user avatar
0 votes
0 answers
26 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 ...
user avatar
2 votes
0 answers
42 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 ...
user avatar
  • 21
0 votes
1 answer
57 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 ...
user avatar
  • 57
3 votes
2 answers
109 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 ...
user avatar
0 votes
1 answer
51 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 ...
user avatar
  • 57
0 votes
0 answers
45 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
user avatar
0 votes
0 answers
43 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)=...
user avatar
  • 1
0 votes
0 answers
48 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 ...
user avatar
  • 11
0 votes
3 answers
63 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 ...
user avatar
0 votes
0 answers
43 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 ...
user avatar
0 votes
0 answers
34 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 ...
user avatar
  • 205
0 votes
0 answers
23 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: $$ \...
user avatar
  • 1

1
2 3 4 5
13