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Questions tagged [control-theory]

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19 views

Transfer function for a quadcopter with linear velocity inputs

I found the control for a quadcopter using the angular velocities or thrust power as the input, but I need a model where I can set the initial and final position (for example, from (0,0,1) to (0,1,1))....
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24 views

H infinity control problem - changing eigenvalues of plant

I'm applying $H_\infty$ approach to control a system with a given input $u$, and I can measure and feedback position and velocity errors. The plant is described by the following transfer function $$...
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1answer
31 views

Controls Project: Help needed finding 3rd order system

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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16 views

Zero-state observability and strictly passive systems

I'm currently studying passivity theorems of nonlinear systems, and I find it difficult to understand the difference between the different kinds of strict passiveness. Are there any intuitive ...
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28 views

Offline Parameter Estimation for second order system - Ordinary Least Squares

I have a second order system which is described by the following differential equation: $\ \ddot{y}+α_{1}*\dot{y}=b_{0}*u $ where $\ y $ is the output of the system and $\ u $ is the input of the ...
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1answer
13 views

Nonlinear behaviour of control plant and adaptive or robust design

In a paper in the context of controller design for DEAP actuators I came upon the following sentence: Furthermore, the nonlinear behavior of the control plant requires either an adaptive or a ...
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1answer
17 views

Adjusting root locus to get a stable system from unstable system

Most of the books that I referred to, used compensators to improve transient performances of a stable system using root locus and compensator design. I got a system which is actually unstable for all ...
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0answers
21 views

value of $\gamma$ in the H-infinity norm

Suppose I have the system: $\dot{x} = Ax+Bu$ $y=Cx+Du$ and the following Hamiltonian matrix: $H=\begin{pmatrix} A & \frac{1}{2}B^TB\\ -CC^T&-A \end{pmatrix}$ I want to find the value ...
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37 views

effect of coupling in MIMO systems

I have a MIMO system with a 2x2 transfer matrix, for example consider: $\begin{pmatrix} \frac{2}{s+1} & \frac{1}{(s+1)(s+2)}\\ \frac{1}{(s+1)(s+2)}&\frac{2}{s+2} \end{pmatrix}$ I would ...
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1answer
163 views

Block diagram vs flow chart?

I was studying a book of control system where i read that a block diagram is a specialized high level type of flow chart So what will be the difference between a normal flow chart and a block diagram?...
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2answers
44 views

Root locus: ambiguity on which branch goes where?

I could not find a Controls Stackexchange, I hope this is the right place, otherwise I would be glad to post it in the appropriate section. My question concerns the root locus method. Given a plant ...
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1answer
43 views

Identification of control system type? Open loop or close loop,

What is the type of control system of door closer in attached photo?
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41 views

Adaptive feedforward cancellation (AFC) and least mean squares (LMS) for periodic disturbance cancellation

I already asked this question here, but since I did not get an answer yet I want to try it here as well: I want to implement an adaptive feedforward cancellation (AFC) for cancellation of the impact ...
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1answer
40 views

control systems vs artificial intelligence?(in nut shell for beginners)

i am confused in basic difference between control systems & artificial intelligence? since both techniques can be used for automation Please kindly try to give answer in nutshell depth/detail ...
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52 views

Maximising the trace of the observability Gramian

Suppose I have a matrix W. This matrix has an observability Gramian Q. Is there a way to see which changes in the matrix W will maximise the trace of Q? Is there a natural way to express maximising Q ...
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13 views

What non-Gaussian filter should I use

I am developing a filter to better predict my state of my system. I had previously tried an Extended Kalman Filter. I have all the data needed to predict my next step but I have few observations/...
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1answer
53 views

Gain and phase margin

Why Bode plots are on jw axis when determining gain and phase margin? Usually it is explained as 1+G(s)H(s) should not be zero and margins represent how far away from this we are. But for showing this ...
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27 views

Meaning of energy method in control theory

What qualifies a energy method in the context of control theory? Citing from a paper to give the context in which this expression came to my attention: One of the challenging problems of the double ...
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0answers
20 views

How does a digital controller's sampling period dictate the system's actuation requirements?

When selecting an actuator for a controls application - e.g. choosing a servo motor for a self-balancing robot - I understand that it's important for the actuators to have fast enough dynamics that ...
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1answer
55 views

Closed loop guidance and control: how to tune a system with multiple feedback controllers?

I'm trying to design a closed-loop guidance system for rockets - something that can be implemented in Kerbal Space Program, for example. To do this, I'm following the design process described in ...
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2answers
56 views

What kind of mechanism can be used to rotate a part in 180 degrees (Ψ (yaw)) and 30degrees in 𝜃 (pitch) direction?

Let's say we have a flat object. We are asked to create some mechanism so that the part can rotate in the shown angles above. What mechanisms can be used?
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1answer
37 views

Designing Block Diagrams For Control Systems

I'm looking for good software to design control systems, and more specifically to neatly design "block diagrams" for control systems. Is there something like that?
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1answer
70 views

Changing fields from mathematics to control engineering [closed]

I did my undergraduate in maths and physics and will be working in control theory for my future job. Not to my surprise, my engineering background is rather lacking. I have taken a look at materials ...
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1answer
47 views

Interpreting Nyquist plot

When implementing the control for my application I got this Nyquist plot which made me flabbergasted. If I zoom on the point $-1 + 0j$ I get the following image How do I interpret this contour going ...
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1answer
83 views

Difference between Hysteresis, low pass filter and deadband in control theory?

I am trying to understand the fundamental difference between the following terms in the context of control systems: Hysteresis Low pass filter Deadband Are these just fancy names that can be ...
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1answer
36 views

How to find Performance assessment (IAE and ISE) of a PID Controlled system?

The Integral Absolute value Error (IAE) and the Integral Squared Error (ISE) is to be analysed. A PID Controller is given as follows: ...
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1answer
47 views

PI controller for second order system

I have a second order system and I need to control it using a PI controller. I need to select the parameters of the controller in order for the system to satisfy a less than 10% overshoot requirement ...
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1answer
52 views

Stabilization of telescope on gimbal using data from encoders and gyroscope

I'm designing a control system for a balloon-borne telescope experiment. As the balloon is constantly moving and the gondola is rotating, I want to stabilize the telescope which can be controlled in 3 ...
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1answer
59 views

Do variables dimensions matter in PID simulation + I want the PID output to be volts?

I have a self balancing robot control loop that uses the PID controller. I feed the robot's angle (rad) to sum block that generates the error between the set point and the angle. The error then goes ...
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0answers
24 views

Observable Canonical Form - Modern Control

I have derived controllable canonical form (very easily), but I have trouble deriving observable canonical form (supposed to be easy.. at least every textbook is implying so). The picture underneath ...
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1answer
67 views

How to use lsim in matlab for a closed loop system

I have designed a system using a minimum realization. I have the A, B, C matrices and I have assigned closed loop poles for the system. I used the place command to find my K matrix. I am wondering ...
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1answer
53 views

In a control block diagram what does a block with an angled arrow through it mean?

I have been looking at papers describing how to do non linear control with neural networks. A lot of these papers have block diagrams with a symbol I don't understand. There is a block with an angled ...
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1answer
33 views

How to tune PID for a step response

I am very much confused finding the time constant and DC gain for the below step response. The idea is to find PI gains for speed control and I am following this tutorial online Tutorial Link Motor ...
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1answer
24 views

Significance of asymptotes in root locus

What is the significance of asymptotes in the root locus of a linear time invariant system. Does it say that for that particular pole on which it is starting doesn't have a practical pole in the ...
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1answer
24 views

Criterion to neglect poles of higher order

If I am having a fifth order system, it is said that the dominant two poles nearer to the jw axis determine the nature of the output, is there any criterion to neglect the other three poles , should ...
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22 views

Why we analyse so much about the underdamped if critically is fastest pls explain

If critically damped system is the fastest and with a smooth curve ...why we analyse so much about the underdamped system.... Please explain if possible quote an example
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2answers
33 views

Why does a lead-compensator type system decrease to a step response

For example, the step response of $\frac{s+1}{s+2}$ is decreasing although its gain is +1, and this system has higher gain at high frequencies than low frequencies based on its Bode plot. But if I ...
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1answer
33 views

How can I tune the parameters of a lqr controller?

From my internet research, it seems there's no systematic way of tuning the design parameters for the LQR controller. I have found Bryson’s rule as an initialization. However I don't know how to ...
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44 views

Control law for nadir pointing spacecraft

Hoping someone here can give me some advice. I've been trying to build an orbit and attitude propagator inside MatLAB and have run into some issues with the attitude propagation due to my lack of ...
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0answers
21 views

Peak altitude control for rocket

I am trying to design a way for a model rocket to have an apogee of exactly 120 ft (or as close as possible). I am using a design similar to the split rudder of the space shuttle on the fins of the ...
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2answers
99 views

What is a definitive discrete PID controller equation?

I need the equation of a discrete PID controller and I find different answers from different websites. For example, here the answer is: $$u[k] = u[k-1] + (K_p + K_i \frac{T_s}{2} + \frac{K_d}{T_s}) e[...
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91 views

Does the characteristic polynomial contains all the poles of a closed-loop transfer function?

The Transfer Function of a Closed-Loop system is: $T(s)=\frac{Z(s)}{1+G(s)Z(s)}$. The BIBO stability of $T(s)$ is guaranteed if all the poles of $T(s)$ have negative real value. In many textbooks I'...
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25 views

Engine Control Unit theory regarding highest priority task?

I am changing career paths and will be working on ECUs/VCUs and associated downstream electronic control modules. I am interested to find a research starting point in terms of Real-Time-Operating-...
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37 views

Defining transfer functions in MATLAB properly

So for a robust control problem I had to use a weighting function of the form: $$ W_P=\frac{0.5s+0.05}{s} $$ And I do so by ...
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0answers
38 views

Can one move the zeros of a transfer function?

This may be a very simple question and I think I know the answer but I would like it to be confirmed by somebody else. My questions regard the zeros of a systems (the roots of the numerator of a ...
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0answers
78 views

Design of a lead compensator with root locus in matlab

For the transfer function G(s), I tried to design a lead compensator for the function to have a response to the step with the following specifications: Overshoot= 10%; Ts (2%) = 5s. When I simulate ...
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0answers
91 views

how to calculate the angle in Nyquist plot

Does anyone know how i can read the angle on the Nyquist plot without knowing the open loop transfer function? So by only having the plot.
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1answer
52 views

How to find BIBO stability fast?

I know that for a system to be BIBO stable the eigenvalues need to be stable so real(lambda)<0 so get that is only valid for 4 but how can i find out the other systems which are BIBO stable?
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1answer
31 views

2-Vehicles platoon stability

Given a system describing a 2-vehicles platoons that can be described as such : $v_k$ the speed of each vehicle $s$ the gap between the vehicles. We can describe the state of the system as : $\dot{...
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1answer
35 views

When is it necessary to consider digial control rather than directly coding in the gain matrix?

I designed a LQR controller and want to implement it on a microcontroller. I don't know about digital control and don't know when to apply it. After a brief research, I found out that I need to apply ...