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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28 views

How does feedback implementation look like in a real word closed- loop process?

I'm looking for a generic term/process that explains how we can make a closed- loop control system. The typical elements of a closed loop systems are controller, actuator, plant and sensors. If you ...
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MPC controller unable to control the height of the quadcopter

I am trying to develop a model predictive controller for my quadcopter. As the equations are non-linear in nature, I linearized the quadcopter at a hovering point. After linearizing, I discretized it ...
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Equations of motion in matrix form and energy consumption

I am working on Lagrangian derived high-dimensional motion equations for a robot in matrix form. The structure of such an equation is known: $M(q)\ddot{q}+C(q,\dot{q})\dot{q}+G(q)=0$ In here, $M(q)$, $...
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29 views

Phase margin by definition

I'm reading about Gain Margin and Phase Margin in a book and having trouble understanding why they calculate the Phase margin like this: <G(Wcrossover) - (-180) = PM Why not: <G(Wcrossover) - (...
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Optimizing error for PID based control of Line Following Robot

I am working to find the optimal PID gains of my line following robot. To do this, I need to optimize any performance index dependent on the error (a typical example is the integral absolute error). ...
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How to simulate open and close and control valve using a simple controller

I have successfully developed a mathematical model for my physical system. My objective is to control the mass of gas in and out of the system. The mass flowrate is given by: $V_f = C_d.\sqrt{2.\frac{\...
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1answer
62 views

How do I study the frequency response of a physical system with Arduino?

I am a control engineering student and I am studying the frequency response of a system, so the Laplace domain, the Bode plot, poles, zeros,etc. ... I have clear grasp of their meaning, but if I think ...
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How to get the performance index ISE and IAE for a Matlab-Simulink designed Line Follower Robot with PID control?

I am researching a method to determine the optimal PID gains for a line follower robot. The problem is, I don't know how to setup the performance index IAE and ISE in the matlab. Any tips on how to do ...
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If there is a instability issue inside the control loop, and the control system starts oscillating, what will be the oscillation frequency?

I have a closed loop controller to control the vehicle on the centerline with a bandwidth of 2 rad/s, and I saw the vehicle keeps oscillating around the centerline in a sinusoid whose period is around ...
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1answer
64 views

How can I make a vacuum pump to move rocks from one place to another?

I am trying to build a vacuum pump by myself and move rocks from one place to another. After some online search, I came across this video on Youtube. I am trying to build something like this. Can ...
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What are some obstacles/issues you face while working in industry? [closed]

As part of a project incubator program at my university, I am trying to understand current specific issues, cumbersome processes, and obstacles facing engineering projects in industry. By pinpointing ...
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34 views

What is the meaning of this symbol in Control System Diagram

I was reading the paper "Full-Speed Range Self-Balancing Electric Motorcycles Without the Handlebar" released in March 2016 by Professor Yang and Murakami in Keio University. I couldn't ...
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1answer
51 views

What is the corresponding transfer function between r and y?

What is the corresponding transfer function between r and y?? I have tried $$ \frac{( \frac{k_i}{s}+k_p+k_d\ s )\times P(s)}{1-(-1)(\frac{k_i}{s}+k_p+k_d\ s)\times P(s)} $$
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31 views

Jacobians and Manipulator Dynamics

This is a Stanford Manipulator I started off working on it by initially setting up the DH table Transformation Matrix and then Homogeneous Transformation Matrix I started finding the linear and ...
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Find system equations for the system shown in the figure and F-V analogous circuit

Can't seem to understand how the 2 bodies would interact with each other. For most other problems I use the Nodal method by using the displacements as nodes and then connecting all other elements to ...
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1answer
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Modeling rigid body dynamics: Trouble with equations, encountering nonsense answers

Hi, I am working on modeling a simple rigid body dynamic system through a certain range of motion. Here is the picture of the system. I am trying to solve the system for the variables $x_1'', y_1'', ...
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Lyaponuv stability condition of linear systems for homogenous P in V(x) = x^T P x

I am currently learning about using Lyaponuv functions to find Linear Matrix Inequalities (LMIs) as conditions for stability of a linear time invariant system. i.e. $$ \dot{x}(t) = Ax(t) $$ is stable ...
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Issue with LQR Q matrix for a cart-pendulum model

I am currently trying to develop a controller using LQR for a Segway. The model that I am using is an inverted pendulum on a massless cart. I have made animations of the uncontrolled pendulum and of ...
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2answers
62 views

Dividing torque of one axle to three in varying proportions [closed]

I want to power a small mechanical monstrosity, which performs three tasks that require three separate axles. For the powering, there's a hand-operated crankshaft connected to the primary axle that ...
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1answer
64 views

What type of electrical machine component for counting time?

I am looking for the proper piece of hardware to do what I'm looking for on my current prototype machine build. I want a timer to begin counting upwards in seconds when a switch is activated, and ...
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39 views

Demonstration of Controlability and Observability

After I studied my Control Engineering courses some years ago, although I was able to interpret the results obtained after calculating the observability and controllability, I haven't been able to ...
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35 views

Robustness to Additive Uncertainty Proof using small gain theorem

I am trying to use the small-gain theorem to prove the robust stability condition for additive uncertainty. I have been stuck on it for a while now. Question: How can I use the small-gain theorem to ...
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40 views

State space representation of a product of transfer functions?

In short, I suppose the question boils down to: If we are asked to find the state space representation of $C(s) \cdot G(s)$, where C(s) and G(s) are both transfer functions, then do we treat them as ...
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Relationship and interpretation of “discrete” and “continuous” covariance matrices in Kalman Filtering

I am quite confused about the interpretations/implementation of the system and measurement noise covariance matrices for the continuous and discrete time Kalman Filter. What I want is to initialize ...
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42 views

Controller to maintain a stable amplitude

I am recording a channel before and after injecting current into that channel. I control the current injection using a switch, when the switch is on current goes to the channel, when the switch is off ...
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34 views

Systematic approach to design a controller

I have four different plant systems which I want to control. They are similar in some aspects (equal inputs and outputs as well as disturbances, all are thermodynamical systems). Furthermore, none of ...
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Increasing convergence rate using Optimal Control and Pontryagin Maximum Principle

My question is in addition to Tuning the optimal control synthesized according to the Pontryagin maximum/minimum principle and choosing the cost function, but requires help from the mathematical side ...
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18 views

Control Partitioning in presence of external disturbance force

I am simulating the dynamics of a control system that has been designed using the control partitioning technique (model-based control + servo control). I am having a query for the case when an ...
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51 views

What are some techniques for improving stabilization given a mechanical time constant?

Problem: I have a self-stabilizing system that utilizes an intertial measurement unit (IMU) attached to the hull of a vessel. The system self stabilizes by performing matrix rotations based on the ...
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1answer
66 views

Pole placement with damping ratio and natural frequency

how can I find out the poles of a system if I have the damping ratio $ ζ = 0.707$ and the natural frequency $ω_n = 2.3\text{ rad/sec}$? $A = \begin{bmatrix} -0.02 & 0.1 & 0 & -9.81 \\ -0....
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0answers
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Find same modulus z plane poles of over damped system

I am asked to find two poles of a second order discrete over damped system that have the same magnitude (0.4, to be exact) in the Z plane. From what I understand, that is not possible since over ...
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1answer
50 views

Input signal rescaling block [closed]

The input signal is limited and lies in range $[-U;+U]$. $U$ - unknown. The output signal must be rescaled to be in the range $[-1;+1]$, i.e. is $+1$ if the input is at steady-state $+U$, and $-1$ if ...
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Nonlinear system with time-optimal control

Given nonlinear system: \begin{cases} \dot{x_1}=x_3+u \\ \dot{x_2}=-x_2+\dot{f} \\ \dot{x_3}=-x_3+x_2 \cdot \alpha \sin(\omega t) \\ \dot{x_4}=-x_4+x_2 \cdot (\frac{16}{\alpha^2}(\sin(\omega t)-\frac{...
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understanding observers and estimators

I have seen several forums related to this question about the difference between observers and estimators in control theory and could not understand it clearly. I wanted to know how the state ...
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1answer
36 views

Zero overshoot criterion from the initial point $x_0$ to the final $x_*$, $x_*$ unknown in advance

Suppose a system is described by the following ODE: $$\dot{x} = f(t,x)+u$$ where $x$ denotes the state of the system $f(x,t)$ is an unknown nonlinear function which meets the following condition: $$ ...
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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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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 ...
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2answers
67 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/...
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2answers
179 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. ...
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1answer
60 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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36 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 ...
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1answer
25 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 ...
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2answers
61 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 ...
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1answer
72 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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47 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+...
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1answer
65 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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37 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 ...
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1answer
59 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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1answer
43 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 ...

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