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.
401
questions
-1
votes
1answer
11 views
Nyquist stability criterion for positive feedback
it is known that the stability of a system with negative feedback may be analized through the Nyquist stability criterion, which is based on observing the number of turns around the point (-1;0) in ...
1
vote
0answers
23 views
+50
How do I add unmodeled dynamics to the system?
I am considering the following paper:
Stability‐and performance‐robustness tradeoffs: MIMO mixed‐µ vs complex‐µ design
and I am having troubles understanding how to handle the unmodeled dynamics of ...
1
vote
0answers
17 views
Moisture sensor for Mixers
I'm looking for alternatives to measure the moisture content in a concrete mixer machine. The ones on the market are expensive, like Hidro-Mix for apparent reasons; mixers are a hostile environment ...
1
vote
1answer
35 views
analysis of PD controller vs static-gain
I have a plant $G(s)$ which gives position and velocity as output
$$ G = [G_{ru}(s)\quad G_{vu}(s)]^T $$
where $G_{ru}$ is the integral of $G_{vu}$, and $u$ is the input to the system. Now if I want ...
1
vote
2answers
28 views
How to convert output of controller (control signal) into PWM signal?
I am trying to control a mechanical system with some transfer function T (output is position & input is voltage). I have implemented a state feedback controller in order for the output of the ...
2
votes
0answers
34 views
Finding coefficients for a PID controller that minimize the integral of the squared error (ISE)
The problem
The problem is to find the coefficients for the P, I and D terms of a PID controller used to regulate the object that minimize the the integral of the squared error (ISE):
$$Q = \int_0^\...
2
votes
1answer
40 views
what is the physical interpretation of poles and zeros of a mechanical system?
what is the physical interpretation of poles and zeros of a mechanical system?
I'm asking things like the meaning if I have only 0 or only complex numbers. And about the number of the poles and zeros, ...
-2
votes
1answer
36 views
Limiting PID controller's output making the plant unstable and untunable
I am using the PID block in Simulink and limiting the output to (+/-)5. The plant becomes unstable and untunable after putting these limits. The plant is stable and tuneable otherwise if no limits are ...
-1
votes
1answer
46 views
Optimal control vs. nonlinear control
I have tried to compare between two courses, and there seems to be some overlap, but not as much. Which method is better when controlling a nonlinear system? Also, what is the main difference between ...
-1
votes
1answer
24 views
What is the minimum frictional force required for a vehicle to operate smoothly, retain traction, and prevent any skids?
I am not looking for a specific number of course. I know that it may perhaps vary with different vehicles. However, I'm trying to figure out how to theoretically calculate the minimum necessary ...
1
vote
1answer
26 views
Aircraft Longitudinal and Lateral Transfer Function Terms
The figure shows input and output variables for both longitudinal and lateral stability transfer functions.
I completely understand what each term stands for but I was wondering what would be the ...
1
vote
1answer
25 views
Doubt on zero pole cancellation
I am looking at a control system which has an unstable pole in the process. The transfer functions of process and controller are the following:
...
2
votes
1answer
25 views
AC Motor On/OFF Control using SSR instead of contactor
I would like to control a 1-phase 3HP motor using a SSR ( the reason being, I need to switch it on/off using a signal (0-5VDC).
Are normal SSRs (ex:Fotek 40A model) capable of handling the starting ...
1
vote
0answers
35 views
Why a zero too close to the imaginary axis gives bad berformances?
I am studying control systems, and I have found that if I consider I control scheme where I filter the reference , if the zero of the pre-filter is too close to the imaginary axis, we have a ...
0
votes
0answers
17 views
Complementary sensitivity function in waterbed effect
I am studying the waterbed effect in control systems, and so I have studeird that from the Bode Integral, if I increase the sensitivity to avoid low frequency disturbances, I have amplification of ...
0
votes
1answer
20 views
Control each axis separately - quadcopter
I would like to know why axis can be controlled independently in a quadcopter. I mean, I was told that you can control $x$ and $y$ independently but I couldn't find a demonstration
Edit: the ...
0
votes
1answer
39 views
Limitations on the control effort
I am studying the mixed sensitivity design for control systems, and I have seen that the control effort has limitations given by the bandwidth of the process and by the bandwidth of the sensitivity ...
1
vote
0answers
27 views
Design compensator to improve yaw rate control performance for aircraft
I am trying to design a compensator to improve the yaw rate ($\dot{r}$) control performance of an aircraft. The lateral dynamics for this aircraft is given in steady space form as following:
where A (...
1
vote
0answers
21 views
Control effort in mixed sensitivity design
I am dealing with mixed sensitivity controller design in SISO systems and I am comparing this approch with the classic approch. In particular, I have placed a weight for the sensitivity function in ...
0
votes
0answers
19 views
Relationship between conjugate poles and resonance peak in frequency response
I have two root locus of two closed loop transfer fuctions, which differ just by a different value of the gain. I have that the one with a larger gain has a reasonance peak bigger in the frequency ...
1
vote
0answers
20 views
How to choose a best sampling rate, according to time constant or bandwidth?
This is a follow up question of Rule of thumb for choosing a best sampling rate
I have a discrete control system with a reference input. The goal is to keep the output close to the reference input (...
0
votes
1answer
20 views
Design the equivalent electric circuit (using op-amps) describing open loop transfer function G(s)
How can I convert the Standard form of the second –order system transfer function into op-amp circuit ?
G(s) = wn^2 / (s^2 + 2ζwns + wn^2)
1
vote
1answer
26 views
I have the yaw rate, rear wheel speeds, and the radius of tires, how to find x and y speeds?
I only have these 3 data sets:
rear right and left wheel speeds (they change with time)
yaw rate (also changes with time)
constant dynamic rolling radius
How am I supposed to find the directional ...
0
votes
1answer
70 views
Rule of thumb for choosing a best sampling rate
I have a discrete control system with known dead time and time constant, where a process variable is sampled at regular discrete time intervals and fed back to the controller. I want to find out an ...
2
votes
0answers
25 views
Problem reading control effort frequency response plot
I am trying to plot the frequency response control effort of a control scheme in Matlab, and in particular I want to do this for different values of tau, which is a constant used to add a pole at high ...
0
votes
0answers
13 views
Unexpected Closed-Loop System Response of Longitudinal Aircraft Dynamics
I have a closed-loop system that represents the longitudinal dynamics of an aircraft with states x velocity, z velocity, pitch rate, pitch, and x and z inertial positions. The outputs of the system (...
2
votes
1answer
52 views
Problem with performances of a control scheme
I am trying to prove with Matlab that if I have an improper system and I place poles at higher and higher frequencies the performances of the system improves. In particular I am considering the ...
0
votes
0answers
24 views
Design op-amp circuit from transfer function
What is the best way to design a circuit based on the following transfer function:
9216 / (s^2 + 48s + 9216)
1
vote
1answer
53 views
What is the mathematical basis for the Ziegler-Nichols method for tuning a PID loop?
The Ziegler-Nichols method of tuning PID control loops has been around since the 1940's, and has been widely applied in many areas of engineering. I understand that it is really only a heuristic ...
-1
votes
1answer
24 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))....
1
vote
0answers
50 views
The optical encoder resolution
The optical encoder has a code wheel with a single track of slots and two photodetectors. The photodetectors are positioned so that they produce signals with a 90 degree phase difference.
I want to ...
1
vote
1answer
78 views
gain margin and phase margin - significance
While gain margin(s) and phase margin(s) in Bode Plots of open loop transfer functions are defined at particular frequencies (when they exist) --- such as phase margin is defined at frequencies where ...
2
votes
1answer
37 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 ...
0
votes
1answer
46 views
Motor, a gearbox and a drum with a cable lifting a mass
A lifting device consists of an electric motor, a gearbox and a drum with a cable for lifting a mass.
The speed after the initial acceleration is $v=0.5\,\text{m/s}$.
The gear efficiency $\eta=0.7$
...
0
votes
0answers
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 ...
0
votes
0answers
32 views
Continuous vs Discrete system simulation in Python
Normally, when you discretize continuous system with zoh method, your continuous system output with the corresponding discrete inputs passed through zero-order hold should be the same at sampling ...
0
votes
2answers
34 views
What type of engineer/professional designs hydroponic farms?
What kind of professional/architect/engineer builds agricultural systems, specifically automated hydroponic systems?
Things such as growing, cultivation, lighting, plumbing, harvesting, processing ...
0
votes
2answers
32 views
Why do we analyse frequency response for step inputs?
In my class I'm in, our lecturer presented frequency response methods such as the nyquist plot and bode diagrams. Then when designing a lead compensator later, he said one of the specifications should ...
0
votes
0answers
26 views
How do I get the closed-loop transfer function of the system, fitted with a PID controller, if the input valve has a transfer function?
How do I get the closed-loop transfer function of the system, fitted with a PID controller, if the input valve has a transfer function given by:
$ \frac{Q(s)}{P(s)} = \frac{Kv}{(Tv*S+I)} $
Where Kv ...
0
votes
0answers
18 views
How to plot the response of the open-loop system when the input discharge suffers a unit step variation using LabView?
The open-loop system is a tank of water connected between two valves.
My transfer function is $ \frac{H(s)}{Q_i(s)} = \frac{R}{A R s + 1} $
My time constant is $ {Tau(T)} = {A R} $
I know how to ...
1
vote
0answers
33 views
How to derive a value from a transfer function
I have a scenario where a valve q_in(t) is pumping water into a tank of height h(t) and area A, which is then pumped out by a second valve q_out(t) that has a resistance to water flow R.
I got this ...
0
votes
1answer
15 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 ...
0
votes
0answers
25 views
How to connect RFD77402 (sparkfun) proximity sensor to Arduino?
I am currently working with distance sensor (sparkfun) RFD77402, does anyone have experience with this sensor, or know how to connect this sensor with arduino? I'm confused about the wiring honestly
...
0
votes
0answers
10 views
Process control on reagent addition system
It's been a while since my fluid mechanics/process control courses at university. Due to my new role I have to dig up the old material again and start refreshing my brain!
There is one scenario ...
0
votes
1answer
32 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 ...
0
votes
1answer
16 views
root locus question - root locus 'begins' at finite open loop pole locations
This is a general question about root locus plots. I notice that there is a source that says:
"The root locus begins at the finite and infinite poles of G(s)H(s)".
Note the part that says 'finite ...
1
vote
0answers
23 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 ...
0
votes
1answer
44 views
Basic question about PID controller
I am a novice in control systems and just learned about PID controller.
So after watching tons of youtube videos I realized that the input of my plant is actually defined by the error. For the case ...
0
votes
0answers
41 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 ...
4
votes
1answer
379 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?...
