PID Theory - closed loop

646

10:55:05

PID systems are used in drones and even nuclear plants. This technique was already used before the invention of electronics, this system is currently implemented through algorithms in a controller or PLC.

In this example closed loop, we can change the set point and also change the process condition and check the deviation between SP and PV.

Sistemas PID são usados em drones e até Usinas Nucleares. Essa técnica já era usada antes da invenção da eletrônica, atualmente esse sistema é implementado por meio de algoritmos em um controlador ou um CLP.

Neste exemplo em malha fechada, podemos mudar o setpoint e também mudar a condição do processo e verificar o desvio entre SP e PV.

published 9 years ago

Antonio1961

9 years ago

For Hurz

hurz

9 years ago

I will check it ;-)

BillyT

9 years ago

Bit hard to validate, only one point of upset trends. And cannot change the setpoint.

Antonio1961

9 years ago

Change Setpoint with swith open.

BillyT

9 years ago

Done that, still only counts as 1 upset. And still cannot change the setpoint.

hurz

9 years ago

I understand this as a demo of PID and not a special given machine to control. So to see the characteristic its fine to do a jump response from to any voltage. It doesn't matter if its 1V delta or 1mV. The characteristic is always the same, as long you do not run into satturation of e.g. the integral part of PID. For a jump response it just needs a dc source and a switch, nothing else. Would be nice to see an real example like a servo motor with all its calculations and models! But that needs some math around, keyword "laplace". There are also some heuristic methodes to find good PID setups. However, the first thing is to find a precise model of what you going to control! Here its, i guess a freely choosen lowpass of 2. order uncritical damped or better said overdamped with 1kOhm resistance.

Antonio1961

9 years ago

Antonio1961

9 years ago

Ok, I fixed it.

hurz

9 years ago

I mean this. Just two voltages/setpoints simple and easy http://everycircuit.com/circuit/6346535909982208

Antonio1961

9 years ago

Correct, the ideal is to have the mathematical model of the equipment and make a predictive controller. However, this is not often done, so we use the PID. Even in predictive control is used an action I - Integral to correct minor flaws in the model and the measurement of the variables that affect the system.

7 years ago

L^-1

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