6 votes
Accepted

When are overshooting controllers preferred over asymptotic ones?

For some systems, the salient criterion is settling time to within some error band. Sometimes you can get faster settling by allowing earlier overshoot. If you need a system to get to within some ...
Olin Lathrop's user avatar
  • 11.4k
6 votes
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Advantage of anti-windup

Anti-windup is a concept for feedback controllers with integral terms, e.g. PID, to keep the integral term from „overcharging“ when regulating a large set point error. It basically saturates the ...
OpticalResonator's user avatar
6 votes
Accepted

Is the PID just an outdated control method and state-space is superior?

I do not think so. Instead of looking directly at PID, lets look at Frequency domain loop shaping in general compared to State-space control (eg, Lead-Lag filters, Notch filters and PID). On top of ...
Petrus1904's user avatar
  • 1,069
5 votes

Why can't proportional gain alone, reduce the error to zero?

To understand why proportional gain won't drive the error point to zero, it is best just to look at the math. Consider the PID loop shown in the image below. The loop algebra in the $s$ domain comes ...
Chris Mueller's user avatar
5 votes
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Is this a PID cascade control loop?

I would not call this a cascaded control loop but rather a MIMO control loop. Typically a cascaded control loop has an inner and an outer loop and the output of the outer loop is used as the setpoint ...
user883521's user avatar
5 votes

How to convert a DC motor into a servo motor using a rotary encoder and a microcontroller?

At the very high level you will need 24V Power supply or a method to generate 24V 24V Motor controller Microcontroller - Arduino is a good place to start There are also prebuild motor controllers ...
Mahendra Gunawardena's user avatar
5 votes
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How do I interpret the following Bode, Nyquist and Nichols diagrams?

Your systems shows extremely close pole-zero cancellation. So much even that it nearly removes 4 poles and zeros. Lets look at why, starting with the Bode plot: The magnitude plot is constantly ...
Petrus1904's user avatar
  • 1,069
4 votes
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Design op-amp circuit from transfer function?

To my knowledge the simplest way to accomplish the transfer function... $$ G(s) = \frac{E_o(s)}{E_i(s)} = \frac{0.0364s}{0.0002s + 1} = \frac{KTs}{Ts +1} $$ ...is the following high-pass filter ...
ConjuringFrictionForces's user avatar
4 votes
Accepted

PI controller for second order system

Step 1: Draw the root locus of the system. Here you can see the two poles of your plant $G(s)$ (marked with an x), at $p_1=-9$ and $p_2=-1$, the pole of your controller $C(s)$ at $p_c = 0$ and the ...
useless-machine's user avatar
4 votes
Accepted

analysis of PD controller vs static-gain

Both the (negated) output and reference are needed to calculate the error. So in the scalar case the reference also gets multiplied by $s\,k_d$, while $T_2(1,1)$ only considers the contribution of $r$...
fibonatic's user avatar
  • 1,653
4 votes
Accepted

Stepper motor speed control problem

Although the advertised advantage of a stepper is that it can be driven "open loop" (no position or velocity feedback required for accuracy, instead you just keep count of the steps) this is only true ...
niels nielsen's user avatar
4 votes

Can I design/tune the outer loop controller without knowing the details of the inner loop controller?

Maybe? Without knowing ourselves anything about the system you have, it's mostly impossible for us to be able to answer the question. However, I can say that in general it is certainly possible to ...
DrMrstheMonarch's user avatar
4 votes

What exactly do I do with the output of a PID controller?

Think of yourself as a PID controller controlling the speed of your car. The PID output is your foot! Is this in units of velocity? No. It's just % pedal push or foot angle. In practice it's just &...
Transistor's user avatar
  • 10.7k
3 votes
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Is lead filter same as PD combined with a low pass filter?

A lead filter implies that the zero has a lower frequency than the pole. While a PD controller with a low-pass-filter does not necessarily imply that order. Also a lead filter (usually) does not have ...
fibonatic's user avatar
  • 1,653
3 votes

What's a control system architecture that can track a ramping reference signal?

Consider a controller $C(s)$ for plant $G(s)$ and feedback $H(s)$. The closed loop is $$\frac{Y(s)}{U(s)}=\frac{CG}{1+CGH}$$ The ramp is $U(s)=\frac1{s^2}$ Thus the error is $$E=Y(s)-\frac{1}{s^...
Arash's user avatar
  • 253
3 votes
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Are all motors controlled with G-Code?

Not really an answer, but I can't comment, so: Does this mean I could in general choose between PID and G-Code? PID and G-code are not two interchangable approaches to control a CNC-machine, they ...
OpticalResonator's user avatar
3 votes
Accepted

Can a PID controller have a simple on/off output?

So typically there is proportionality and a continuously varying (analogue) output. Correct. This could be an analog voltage or a digital value. In the case of a simple process like a domestic gas ...
Transistor's user avatar
  • 10.7k
3 votes

Limiting the integral to a time window in PID controller

Any question that asks "would it make sense" in control systems has the answer "that depends on your plant". In the case of a limited time horizon integrator, you're turning your integrator from ...
TimWescott's user avatar
  • 2,652
3 votes

Basic question about PID controller

But what if my error is zero and plant works ideally? meaning there is no history of error being anything other than zero. So three terms have been and will be zero. Does that mean the input of my ...
TimWescott's user avatar
  • 2,652
3 votes
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Is it necessary to use PID control in my use case?

Even if you can tune a function as per your needs, using proportional control(P) only you can never fully eliminate error from the system. Error is inherent in P control. Using I control along with P,...
anshul suri's user avatar
3 votes
Accepted

Best PID autotuning algorithm/library for simple heater problem

First of all, I'm not an expert, but I'll try to give you basic answers listing all that I know as state-of-art. Also, I'm going to update the data with the feedback that people can give or adding new ...
Pablo Díaz's user avatar
3 votes

Best PID autotuning algorithm/library for simple heater problem

Marlin firmware has an autotuning algorithm, so you could either upload marlin to your board, or hook up a dummy board with marlin on it -> autotune -> get PID vals, and then apply them to the ...
Benjamin Fasken's user avatar
3 votes
Accepted

Why does accuracy of temperature PID controller drop over time and how to eliminate it?

IMHO the problem you observe is mainly related to limitations of your system. Notice, that up until 55 degrees C the heating element can follow the gradient of temperature wrt to time. Just after 55 ...
NMech's user avatar
  • 24.3k
3 votes
Accepted

What is the physical intuition behind an "integrator" in control theory

An integrator is something that "remembers" how long a steady-state error has persisted and ramps the gain in proportion to how long the error has existed. So, imagine that we have a chart ...
niels nielsen's user avatar
2 votes
Accepted

Square shaped position error

Your system is not reaching the target value. Possibly this is due to static friction in the actuator mechanism, which causes it not to move until the force exceeds some threshold. Assuming you are ...
jpa's user avatar
  • 1,943
2 votes
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Is it important to have a good behaviour inside internal loops of a cascaded PID controller?

In general, poor performance of PID2 will cause poor performance in PID1, in both disturbance rejection and setpoint tracking. There are some special instances where poor performance of PID2 in the ...
OldUgly's user avatar
  • 136
2 votes

How to design a PID controller for MIMO systems in which there are more outputs than inputs?

It really depends on the logic required for your system. I don't think there is a hard fast mathematical solution like there is for a standard one-input one-output PID. In many cases a PID may not ...
ericnutsch's user avatar
  • 8,106
2 votes

What means the velocity constant of the integration in PI controller formulas?

Quick Answer The $R$ in the PI controller equation would best be described as a "weighting factor" that determines the influence of the integral term relative to the proportional term. The ...
BarbalatsDilemma's user avatar
2 votes

What is a PIAD controller?

The A could be acceleration. The acceleration part is then used as feedforward or feedback in addition to the ordinary P, I and D parts. Take for instance a height controller for a quadcopter. For an ...
Mika Sundland's user avatar
2 votes
Accepted

What type of control system is this? open loop?

This system can be considered "closed loop," since the control input is being determined by some sort of feedback loop (even though the mathematical expression of the feedback loop through the ...
BarbalatsDilemma's user avatar

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