Questions tagged [control-theory]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
0 votes
0 answers
20 views

Derive equation of the lead compensator [closed]

Referring to the closed-loop system shown in Figure below design a lead compensator Gc(s) such that the phase margin is 45°, gain margin is not less than 8 dB, and the static velocity error constant ...
user avatar
  • 1
1 vote
1 answer
57 views

Linearization about equilibrium point 0 in the presence of unknown input

Consider a SISO non-linear system $$\dot{x} = F(x,u)$$ in which $\vec{0}$ is an equilibrium point. In the process of determining that it is indeed an equilibrium point, the input did not matter at all....
user avatar
1 vote
1 answer
47 views

Control Engineering: Formal vs. Trial-and-Error

At university, my control engineering courses are focused on a more theoretical approach, but the main message from our professors was clear: When designing a feedback controller (PID, H-infinity, MPC,...
user avatar
0 votes
1 answer
44 views

Intuition for blocks and Laplace form for cascading transfert function

I'm failing to understand Blocks in block diagram in control theory. Indeed, the link between transfer function of time and function of Laplace is fuzzy to me. I'm looking for a way to ground my ...
user avatar
  • 1
0 votes
1 answer
54 views

Which controller is more suitable in this scenario? P, I or PI controller?

Scenario: A robot has a ultrasonic sensor which measures the distance to the nearest object in centimetres. The robot has two motors, a motor for the left wheels and a motor for the right wheels. The ...
user avatar
0 votes
0 answers
59 views

How can I find characteristic equation of complex systems?

I am working on an Overhead crane, where I am supposed to design a controller that controls the position of the crane while minimizing the load's sway angle. I have derived the transfer functions for ...
user avatar
0 votes
1 answer
39 views

Contradiction of bandwidth and damping

I am studying control theory and mechanical vibrations. From control theory aspect, I know that bandwidth and response time is inversely proportional, which means bandwidth and damping as well. But in ...
user avatar
  • 1
1 vote
0 answers
28 views

What's a real life example of linearization of a system around a fixed point

I'm tasked on finding a example of a real non-linear control system. a real paper or publication on a website like the IEEE thats describes the model of the system so I can then linearizy it around a ...
user avatar
0 votes
1 answer
48 views

Bode plot phase margin concept details

I know a closed-loop system $\frac{G}{1+G}$ is unstable when the open-loop transfer function $G$ equals -1 or $0dB\angle-180^{\circ}$. The denominator becomes 0 so the gain is infinite. This is why ...
user avatar
  • 1
0 votes
0 answers
20 views

Phase margin concept: why can there be instability when the gain never reaches 0dB?

If the open-loop transfer function is always below 0dB but the phase crosses or approaches 180 degrees, the closed-loop system can still be unstable. Why? Example: open-loop transfer function $\frac{0....
user avatar
  • 1
0 votes
0 answers
15 views

SMC: Is there a way to control two sliding surfaces with just one control input?

This is a question related to Control Systems. I've been searching papers all over the internet with very little success. I know that traditionally we want one control per sliding surface but If ...
user avatar
  • 103
0 votes
1 answer
36 views

Deadbeat gain for system with measurement delay

Say we have SISO system (e.g. the velocity of a permanent-magnet motor) that we're controlling with proportional feedback, with the condition that our measurements of the process variable are delayed ...
user avatar
0 votes
0 answers
34 views

How to control speed of DC Gearmotor with Varying Torque

I have a system where the torque is constantly changing, but I need the speed to remain at 9RPM. I have enough room for error where I can be between 8 and 10RPM. How can I achieve this? All I can find ...
user avatar
0 votes
0 answers
30 views

Modelling an S-shaped Second Order Process Response

I am trying to model an S-shaped second order process response as a transfer function in Simulink, as shown in figure 3 in the linked article. Ideally the response should be overdamped. I have tried ...
user avatar
0 votes
1 answer
66 views

Unexpected uncontrollable double integrator system during reference tracking (augmented state-space)

I'm trying to design a controller that will achieve reference tracking of the second state for the following system. $$ \begin{aligned} \dot{x} &=\underbrace{\left[\begin{array}{ll} 0 & 1 \\ 0 ...
user avatar
0 votes
0 answers
15 views

Kalman Filter but for control variable from finite horizon controller

I am running a closed loop simulation, using a convex controller that uses simplified linear equations of motion to calculate the control variable w. The controller considers a limited number of ...
user avatar
0 votes
1 answer
37 views

Stability properties of controllers with independent control laws applied in underactuated systems

I am interested in designing a GNC controller for a 3DOF underactuated vehicle that follows a path in 2D space. The two available control inputs are the thrust force in the surge direction and a ...
user avatar
  • 1
0 votes
1 answer
122 views

How to model the state space matrix of a pendulum?

Here's an image of the problem: I'm trying to put the following problem in matrix form (state space) but I don't know how would I put -(g/L)sin(x1) in the A matrix since the x1 value is inside the ...
user avatar
  • 103
0 votes
1 answer
72 views

Full state feedback with integral action - Matlab script

I made this Matlab script to implement a dynamical system with full state feedback and integral action. Maybe I'm wrong in implementing the integral action because the system diverges. First I ...
user avatar
  • 5
0 votes
1 answer
122 views

Dynamical system problem

I have this dynamical system: A = [ -0.313 56.7 0 -0.0139 -0.426 0 0 56.7 0]; B = [0.232 0.0203 0 ]; C = [0 0 1]; D = 0; I'm ...
user avatar
  • 5
0 votes
0 answers
44 views

Finding optimal PID gain values with no Transfer Function or Plant model

Background: I have a Matlab simulation model with .m files. The functions simulate a speed control system of a vehicle. I can control the vehicle's speed by adjusting the vehicle’s acceleration and ...
user avatar
0 votes
0 answers
36 views

Control scheme for roll compensation

I'm working on an application that rotates a cylindrical mass in a manner to compensate for roll in a boat. The roll of the boat is rather slow so I was thinking it might be possibly to simply use a ...
user avatar
  • 1
0 votes
1 answer
78 views

Definition of Bandwidth as angular frequency

I am searching for a Formal Definition of bandwidth given the transfer function of a system, or the bode plot. Is it the frequency $\omega_b$ in which $$20log|H(j\omega_b)| = -3\text{dB}$$ or $$20log|...
user avatar
0 votes
0 answers
26 views

Best Techniques to design a cascaded precision position controller

I'm looking to design a cascaded controller to transform a BLDC into a servomotor. The system has a motor current controller in the inner loop, which is controlled by a torque controller, which is ...
user avatar
0 votes
1 answer
55 views

What are disadvantages if increasing the gain Kd for a PD(Proportional Plus Derivative ) controller

What are disadvantages if I increase the gain Kd for a PD(Proportional Plus Derivative) controller, someone told me larger gain for derivative error for will reduce the stability margin, while the ...
user avatar
  • 57
0 votes
1 answer
51 views

How could I compute the stability margin from a closed loop response?

Why the stability margin is typically computed by the open loop response or transfer function rather than the closed loop response or transfer function, how could I measure/compute the stability ...
user avatar
  • 57
0 votes
0 answers
43 views

Additive perturbation

consider the following transfer functions: $$ G(s)=\frac{1}{\tau s+1}G_0 \quad \tau_{min}<\tau<\tau_{max} $$ show that this system equal to model with additive perturbation as follow $$ G(s)=...
user avatar
  • 1
0 votes
0 answers
46 views

Limitations to consider when picking a cut-off frequency low-pass filter for PID control?

Considering a first-order low-pass filter transfer function: $$ \frac{\omega_c}{s + \omega_c} $$ Where $\omega_c$ is the cut-off frequency. Are there any limitations on where to place this pole? For ...
user avatar
  • 11
0 votes
0 answers
34 views

Block-diagram combining two controlled subsystems

I have two subsystems which are shown in the picture below. One of them is a system of stable and controlled differential equations of a mechanical system. Second is a block that implements a function ...
user avatar
  • 205
1 vote
0 answers
52 views

(Dominant) Poles very close to zeros in PID control

I have a plant transfer function $G(s)$: $$ G(s) = \frac{1}{s^2(0.1s + 1) } $$ I want to control this with practical PID control: $$ C(s) = k_p + k_i \frac{1}{s} + k_d \frac{N}{1 + N \frac{1}{s}} $$ ...
user avatar
  • 11
0 votes
2 answers
81 views

How to tune a PID controller when plant's step response looks like a ramp?

The system is a boat and I want to specify a yaw angle and the PID controller would operate the rudder of the boat in order to reach the desired yaw angle. So, the step response of the plant (boat) ...
user avatar
0 votes
0 answers
32 views

What is residual oscillation and critically damped oscillation in the context of a controller's performance?

What do these terminology "residual oscillation" and "critically damped oscillation" mean when evaluate a controller's performance? How are they related to the stability of the ...
user avatar
  • 57
0 votes
0 answers
27 views

How to determine time constant/cutoff frequency of the filters in the controlled loop

I was told to be careful to use filters in the control loops as it will add extra time delays in the system and degrade the system dynamic response, but I also saw there are lots of filters in ...
user avatar
  • 57
1 vote
2 answers
64 views

How could I verify the stability of a real system with non-linearities?

For a closed loop system, I could do the stability margin analysis using linear method like bode diagram, but in reality there are non-linear elements in the system like saturation/rate limits inside ...
user avatar
  • 57
0 votes
1 answer
58 views

Could someone explain how a compensator shifts the root locus?

I'm reading a root-locus course note from MIT. However, I can't understand this part: How does adding a compensator with a pole at origin remove the plant pole on the right half-plane into the left ...
user avatar
1 vote
0 answers
40 views

Sliding-mode control is a model-based technique?

The sliding mode control can be considered a model-based control? In my opinion yes since takes the information of the mathematical model of the system to be controlled handling with possible ...
user avatar
  • 125
0 votes
1 answer
64 views

Controls System experiment

We performed an experiment in which we turned a bicycle on its side and placed a piece of green tap on one of the spokes. We spun the wheel and recorded the wheel spinning until it came to a complete ...
user avatar
2 votes
1 answer
64 views

What should be the sample frequency to test the response of a filter?

I am testing the frequency response as a filter as below, what should be the sample rate of the chirp signals, someone told me it should be at least 2 times of the input signals frequency, someone ...
user avatar
  • 57
1 vote
0 answers
68 views

Stability from Gain and Phase Margin

I know that a system with positive gain and phase margin is a stable system. And the one with a negative gain and phase margin is unstable. What will a system with negative phase margin and positive ...
user avatar
1 vote
1 answer
61 views

Is It Possible to Have a Continuous-Time System Controllable but Discrete-Time System Uncontrollable?

I have a continuous-time state-space system $\dot{x} = Ax + Bu$ with $A = \begin{bmatrix}0 & 0 & 0 & 1.0000 & 0 & 0\\ 0 & 0 & 0 & 0 & 1.0000 & 0 \\ 0 & 0 &...
user avatar
0 votes
0 answers
21 views

Is it possible to calculate Over Shoot percentage and settling time of an Underdamped 2nd order system with Ramp input?

Most of the books derive Over Shoot percentage, settling time for 2nd order underdamped it for unit step response. Do these parameters exist for 2nd order underdamped system for Ramp response too? If ...
user avatar
1 vote
1 answer
41 views

Excluding the transient in computing RMSE in control algorithm implementation

I have implemented a control algorithm and I would like to study its performance by looking at the trend of the tracking error and then algebraically transpose what I visualize, I have thought to use ...
user avatar
  • 125
0 votes
1 answer
60 views

Unstable System. Error Trying to model the Red Bull Stratosphere Free Fall

I tried to model a problem months ago and still I can't solve, I don't want forget this problem so I would like to share what I tried and if you know what is happening with my graph. This is the ...
user avatar
1 vote
3 answers
434 views

If a control system is unstable does it mean it will oscillate?

When a plant is known to be unstable, does it mean it will have an oscillation response?
user avatar
  • 33
0 votes
0 answers
39 views

Examples of model-based control techniques

I am trying to find out the differences between the model-based control approach and the data-driven one. Surely the main difference is the latter's independence from the information of the ...
user avatar
  • 125
3 votes
0 answers
55 views

PI or PID-regulator for control system with hysteresis relay in inner loop

I have such control system (sorry for rough drawing :) ) $G(s)$ - stable object with proper transfer function. $1/s$ - integrator. I need to clarify, how synthesized PI or PID controller for such ...
user avatar
  • 205
2 votes
1 answer
55 views

Full state feedback of a closed loop system

Does Full state feedback gains affect the dynamic or steady state gain of a closed loop system?
user avatar
  • 33
0 votes
0 answers
49 views

How do I find the gain from the root locus with given perfomance, where I know the real part of the poles?

I have an exercise to draw a root locus plot and determine its gain to make sure that it fulfills the performance requirements. the given system G(s) is $$G(s) = \frac{1}{s^2+s}$$ And the given ...
user avatar
  • 1
0 votes
1 answer
61 views

Quality of the transient response for an arbitrary transfer function

The question is simple and I rather need a reference point. How the parameters of transients are estimated (as in the picture) from an arbitrary linear transfer function (formula is given).
user avatar
  • 205
0 votes
2 answers
103 views

Why prefer a discrete-time system because of a practical implementation instead of continuous one

I have previously done this question on math stack, and I think that maybe here is better. I am studying the theory of discrete-time systems, comparing them with continuous ones in the control theory ...
user avatar
  • 125

1
2 3 4 5
8