Questions tagged [control-theory]

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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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16 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
39 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
38 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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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
62 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
43 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
38 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
22 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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26 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
44 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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21 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
31 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
41 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
31 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
19 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
20 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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27 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
29 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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42 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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20 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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1answer
53 views

Discrete PID controller

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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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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21 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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34 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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36 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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60 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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73 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
44 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
28 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
31 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 ...
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1answer
28 views

How can I calculate the maximum possible deviation from equilibrium, that can still be compensated, given a limitation on the control input?

For example we have an inverted pendulum attached to a cart, with the cart having a speed limitation. Having derived the linearized model, how can I calculate the maximum possible deviation on the ...
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49 views

Is there a maximum phase margin a PID controller can give?

I'm having trouble understanding the plot attached. The bode plot here shows the bode plot of a plant to be controlled with PID. So, if I want a phase margin of 30 degrees at the bandwidth frequency, ...
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1answer
65 views

Control system for a temperature controller

I have adapted a refrigerator to create a temperature controlled environment for brewing beer. I have mounted an electric heater coil inside the fridge and configured a basic controller to maintain a ...
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0answers
52 views

How can I find left and right directions associated with each zero for a MIMO transfer function?

How can I find left and right directions associated with each zero for a MIMO transfer function? Intia First it can be expressed in Smith-McMillan form and can find poles and zeros. Then how to find ...
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1answer
56 views

Control: control action of a PID controller with feedback

I'm programming the controller for a drone and I've got a question that may be basic, but I need to understand this perfectly to continue with the most interesting part of the project. The sensors of ...
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0answers
33 views

What is the principle behind controlling thermoacoustic combustion instability with a speaker?

From "ThermoAcoustics and the Rijke Tube: Experiments, Identification, and Modeling", thermoacoustic instability can be subsided using an amplifier and a speaker. It says in page 4, The microphone ...
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87 views

3 DOF SISO state space control

As part of a control systems course I have to implement control for a 3 DOF SISO mass spring damper model of a robotic cutter arm. The arm is to follow a 5Hz triangle wave reference which is ...
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2answers
63 views

Books for learning PID control? [closed]

I am aiming to program a quadcopter flight controller as a personal project. To be able to do this I understand one of the fundamentals is a PID control system . So my question is does anyone have ...
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1answer
41 views

Zeros of a Trransfer Function

I would be grateful if someone could explain me what does the value of zeros of a transfer function tell about the dynamics of the system.
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1answer
76 views

Control systems, Nyquist plot and root locus

I need help in understanding the connection between Nyquist plot and root locus plot. Let's say I have a Nyquist plot, what can I infer about the root locus plot? and vise versa. Given the root ...
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1answer
79 views

Control of second order undamped system

I have the following differential equation: $$\ddot{\psi_t} + \omega^2 \psi_t = \omega R_s i_f - \omega u_f + \dot{u}_t - R_s \dot{i}_t$$ where $w$ is the electrical speed of the motor. I have ...
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1answer
109 views

what's wrong with this robust control scheme?

I'm learning how to control a double integrator with $H_\infty$. my model is simply $$\begin{gather} \dot{r} = v \\ \dot{v} = F/m \\ r(t_0) = 0\text{ m}, $v(t_0) = 0\text{ m/s}, m = 1000\text{ kg} \...
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1answer
82 views

Cruise Control Project on Toy Car

I finished taking my control theory course, and I want to build an RC car that has cruise control. So I started off with the force analysis, and I got external forces that are constant. For example if ...
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1answer
44 views

Using place command in MATLAB using different state representation

I had a transfer function $$\frac{10s+20}{s^3+10s^2+24s}$$ and I found the state space representation of the above using MATLAB. Using $place(A,B,[poles])$, I found a gain matrix K that corresponds ...
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1answer
170 views

How to control a multi input single output heating system?

I am trying to optimize the heat control of a test bench at our facility. The test bench is basically a pipe with an air flow that can be heated up to desired temperature. To heat the air flow up ...
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1answer
50 views

Transfer function with cancellable zero pole and controllability

I have a transfer function (From Ogata's Modern Control Engineering) $$\frac{s+2.5}{(s+2.5)(s-1)}$$ and the theory says the system has a pole zero cancellation and is uncontrollable. They said that ...
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2answers
143 views

LQR control and system dynamics linearization

I recently finished a project that simulated the dynamics and control of a 6DOF quadcopter model using a state-space LQR control approach, but I had a few questions that I wanted to ask that might ...