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.
539
questions
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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 = ...
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0answers
18 views
HVAC Condensor Liquid Level/Ratio Estimate
Let's say I have a simple condenser inside of a HVAC system with 1 point of entry(Super-heated Vapour) and 1 point of exit(Saturated Liquid) for my refrigerant r134a.
A pipe passes through it with ...
1
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2answers
63 views
Fault Recovery of a UAV using MATLAB
I'm currently investigating fault recovery in a UAV using MATLAB.
I've been given several variables:
phi = the roll angle
psi = the yaw/heading angle
beta = the side slip
p = roll rate
r = yaw/...
2
votes
2answers
142 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
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1answer
39 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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35 views
Torque control of servo motor
I have an EtherCAT loop with a servo motor that is controlled at 2kHz. An outer loop running at 1kHz has to calculate the demanded torque for the servo motor and send it through UDP.
The motor needs ...
0
votes
1answer
18 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 ...
2
votes
2answers
57 views
How can I ensure steady flow to all the valves?
I've set this up for my hydroponics water distribution system. The water is pumped up, and is distributed via the valves. I can manual control the valves so that each outlet has a steady flow of ...
0
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1answer
52 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 ?...
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39 views
how derivative gain in PD controller influences tracking error
List item
For a proportional and derivative feedback control, the the response and tracking error in frequency domain can be represented as
$Y(s)=\frac{KG+K_dSG}{1+KG+K_dSG}S_p \\
e(s)=\frac{1}{1+KG+...
2
votes
1answer
64 views
To stop or to go around?
Let us we are moving in a car. There is a wall in front of us, we need to decide can we go around it or not. It is known that width of the wall is $w$ and our speed is $v = const$.
What is a simple ...
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2answers
32 views
Is controlling humidity more precise when calculating with relative or absolute humidity?
I have a tubing system where I need to precisely control relative humidity. All my sensors are giving me temperature [°C] and ...
2
votes
1answer
56 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, ...
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0answers
22 views
Can someone please explain what a PT1 filter is in simple terms?
The context here is for determining how driveability filters are calibrated since most of them use pt1 filters to filter the torque demand.
0
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1answer
38 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 ...
2
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0answers
31 views
Why using Tyristor (SCR) for inverting the DC voltage in HVDC systems?
In High Voltage 3 PHASE Transmission Systems the voltage needs to be rectified (from the AC generation source to DC), transmitted, and then inverted back (From DC to AC). For doing this, usually LCC (...
0
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1answer
42 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
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1answer
26 views
Transfer Function
Hi Guys I am trying to evaluate the following transfer function below can anyone verify if this is correct
$$e_i = -d_{r,i} + d_i $$
$$d_i = q_{i-1}-q_i$$
$$d_{r,i} =H_iq_i$$
$$Therefore, e_i = -...
2
votes
2answers
104 views
What is a “typical” in the context of control engineering?
When talking about control systems I sometimes hear the term "typical", however I have no clear understanding what it is. It's also mentioned in some codes (so far without definition), here'...
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1answer
35 views
Closed Loop transfer Function
Hi Guys wanted some help for breaking down a block diagram which can be seen below. I know that typically with feedback systems be it negative or positive you would employ using the following:-
Close ...
0
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1answer
41 views
Determine the parameters for this given nyquist plot
I have seen quite many of this type of question and I want to find how to solve them but I haven't cracked it yet. For example this is one:
My thoughts so far:
Replace $$s \rightarrow j\omega$$, $$G(...
0
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1answer
46 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
1answer
101 views
Is the PID just an outdated control method and state-space is superior?
So I've been wondering this for a while; is PID just a simple but slightly outdated control method / isn't state-space (SS) a far superior method in pretty much every way?
SS allows for MIMO, PID just ...
2
votes
2answers
107 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 ...
0
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3answers
46 views
Liquid Level Control System Resistance
In the figure attached for reference, it is given that if $R_1$ is the resistance element of valve 1 and τ ∝ $R_1$, but I am not able to understand it intuitively.
If $R_1$ is high, output flow ...
1
vote
2answers
48 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
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4answers
83 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 ...
0
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0answers
36 views
Optimal control of the gradient type PDE
I recently encountered the following optimal control problem.
The purpose of the system is to find the parameter $x$ at which the maximum or minimum of the function $f$ a is reached. $x$ is unknown to ...
0
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1answer
55 views
Steady-state tracking error has to equal zero, what values do I need?
A block is used to model instruments with limited capabilities to provide inputs to the plant. A seen below:
The output of the block 𝑢𝑎 is related to the input 𝑢 with the following input-output ...
0
votes
1answer
51 views
PID Control: Is adding a delay before the next loop a good idea?
I am implementing PID control in C++ to make a differential drive robot turn an accurate number of degrees, but I am having many issues.
Exiting control loop early due to fast loop runtime
If the ...
1
vote
1answer
71 views
What's the difference between Fuzzy PI, PD and PID controllers?
I am investigating fuzzy control and I am a little confused, I have come across 3 models and I can't quite fathom out what is going on.
In this PD+I controller, I can see the error signal being ...
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36 views
Controlling the dynamics of nonlinear systems with an unknown steady state
On the one hand, the question is simple, on the other hand, I need the help of specialists in control theory.
Let's take a simple gradient dynamical system:
$\frac{dx}{dt}=\frac{df}{dx}$
where $f=e^{-(...
2
votes
3answers
154 views
How to convert a DC motor into a servo motor using a rotary encoder and a microcontroller?
Operating/ Rated Voltage: 24V
No load Speed: 350 rpm
No load Current: 150mA (max)
Max efficiency: 1.4 Kg-cm/300 rpm/ 14.2W/ 0.87A
Max power: 4.5 Kg-cm/180 rpm/28.2W/1.4A
Stall Current: 2.9 A (max)
...
0
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2answers
45 views
How to calculate frequency response of the system? and find missing values [duplicate]
I can convert the H(s) into the frequency response which is:
𝐻(𝑗𝜔) = 𝜇(𝑗𝜔/(1+ 𝑗𝜔𝜏))
and the output in the steady state is:
𝑦(𝑡) = |𝐻(𝑗2)|sin(2𝑡 + ⟨𝐻(𝑗2))
The phase: ⟨𝐻(𝑗2), has to ...
1
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1answer
25 views
What does “analytical design” mean?
What is meant by "designing analytically" ?
Especially in control systems design
Does it mean theoretically design?
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1answer
139 views
Find the point where locus crosses the damping ratio line?
Given a transfer function, find the point where locus crosses the damping ratio of 0.5?
$$G(s)= \dfrac{K(s-2)(s-4)}{s^2+6s+25}$$
The textbook only shows this solved by Matlab or program, I would like ...
0
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1answer
29 views
How to manage two control loops as safety when BPCS is shared?
I am trying to wrap my head around some excerpts from:
CCPS Layer of Protection Analysis
CCPS Guidelines for Independent Protection Layers and Initiating Events
IEC 61511
I am trying to understand ...
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0answers
24 views
How could we calculate the coefficient of a PI controller (ki - kp) which regulates the voltage of the DC bus link of a three-phase inverter?
From my calculations I arrived at a non-linear equation :
$$ C\frac{dV_{dc}}{dt} = 3e_q\frac{I_q}{2}V_{dc} - \frac{V_{dc}}{R_{dc}} $$
I have calculated the operating points which are $I_q = 9.58A$, $...
0
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1answer
33 views
Is it true that points of root locus only satisfiy the angle condition?
So , I was reading a course book : ''Modern Control Engineering '' by Ogata and I came forward this statement that made me skeptical:
''The points of root locus only satisfiy the angle - condition. ...
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0answers
22 views
Absolute Digital Encoder Speed measurement
I am using a 16-bit absolute magnetic encoder and I get the position from SSI 3 wire, I mean digital outputs for my position control application. I have a problem with getting accurate speed data. I ...
0
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1answer
37 views
Why not to calibrate accelerometer in IMU filters?
I have been reading various research papers regarding IMU filters and I came to the question of why do we not need to calibrate the accelerometer values as we do for the gyroscope and magnetometer?
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32 views
How to design a kalman filter with different sampling rates?
This question is related to https://stackoverflow.com/questions/22598107/kalman-filter-with-redundant-state-measurements.
How would one design a Kalman Filter (or EKF) when two measurements of the ...
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1answer
49 views
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15 views
PSCAD question regarding how to use graphs
so this question is to do with coursework, but I just need some guidance as I am not exactly sure where I'm going wrong. I missed my 2 weeks of practical classes due to my roommate having covid-19, so ...
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60 views
Choice for HEAVY blacksmith table
I have an old 7,000 lb. blacksmith table (I had it weighed at truck stop). Similar to the one this man has:
Sorry for the size of the pic.
I need to lift one end the way he is doing and I have a farm ...
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0answers
28 views
Evaluating Steady State Error Constant for a Discrete Time Control System with Kronecker Delta Input
Hello there, hope you are doing well.
I am working on a Discrete Time Control Systems homework and at a certain part of it, the question asks me to find the steady state error of the system. I ...
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0answers
37 views
How to model a double transfer function in Simulink?
I'm trying to model an actuator in Simulink based transfer functions previously derived.
One of functions is $$\omega_p=G_2(K_cG_1V_c-c)$$ where $$G_1=\frac{K_e}{\tau_es+1}$$ $$G_2=\frac{1}{c+...
0
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1answer
34 views
Closed loop compensator
What does it mean if you've been told to design a compensator to ensure that the closed loop phase margin is at least 120 degrees? Isn't a compensator typically designed using the open loop transfer ...
0
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1answer
68 views
Is using a 4x4 bolted to the face of 2x12 enough?
I am working on a project that has three 2x12’s supporting a load of 12,000 lbs. similar, but not exactly, to how joists support a house.
The 2x12’s are supporting about 6,000 lbs. on each end.
The ...
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1answer
53 views
Changing the quality of the transient process in a nonlinear system (Part II)
My question is a continuation of the topic.
https://math.stackexchange.com/questions/3910814/changing-the-quality-of-the-transient-process-in-a-nonlinear-system-in-mathemat
Unfortunately, last time I ...
