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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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/...
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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. ...
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36 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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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 ...
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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 ...
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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 ...
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51 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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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+...
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63 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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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 ...
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1answer
53 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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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.
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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 ...
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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 (...
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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 ...
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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 = -...
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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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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 ...
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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(...
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43 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 ...
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98 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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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68 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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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^{-(...
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151 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) ...
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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 ...
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24 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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100 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 ...
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28 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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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 $I_q = 9.58A$, $...
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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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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 ...
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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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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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49 views

What does this P&ID symbol represent?

The symbol: Here is a part of the diagram:
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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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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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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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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+...
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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 ...
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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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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 ...
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control block diagram design

I have a pump [m^3/(sV)], a tank [no units], a valve [m^2/s] and a level sensor [m/V]. The units are for the gains in the respective transfer functions. How should i connect my control block? Where ...
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Covariance of an uncertain vector going through an uncertain rotation

I have a vector $\omega$ and it associated covariance, a rotation $\mathbf R$ and its associated covariance. What is the covariance of $\mathbf R \cdot \omega$ ? More rigorously: I have an estimation ...

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