Application of Proportional Control

We are students of electrical engineer at São Francisco University (Campinas - SP - Brazil) and we are at sixth semester of undergraduated level. This semester we want to develop a great project in the control area: including the control aspect, analog and digital electronics and applied electrical circuits (passives).

Our Group is composed per five people, and our challenge is to design a circuit with  "Proportional Control".

What is this?

Proportional Control is a kind of control circuit or system that applies a proportional correction in a process variable that is out of  a certain set point. For example: we will control a LED Brightness seted to a desired value using a LDR sensor readings, in case of any object attenuate the light in LDR sensor, we will apply the proportinal corretion to the LED, thus, keeping always the same brightness!!!

At first , we will implement proportional control in the circuit, during the design phase we will try also to implement other kinds of control as PID (Proportional, Integral, Derivative). Due to the fact that proportional and integral controls has much more complexity and we need much more time to design this kind of circuit. Let´s see what happens :-) ...

The diagram below illustrates the operation of the control loop:

The figure below shows a model of LED and LDR sensor.