Proportion Integral Derivative (PID) Control
Proportional Integral Derivative control is an algorithm used to stabilize a stream of data at a set point. The control method utilizes three aspects of the data: the proportion (the distance the current data point is from the set point), the integral (using the set point as 0), and the derivative (of the current data point). Each of the three components has a coefficient that can be changed to alter the curve. Each component is multiplied by the appropriate coefficient, and their sum yields the value given to the device that affects the data stream. Since we only care about the data point in relation to the set point, the error (E) is used for calculations. Below is the basic equation for PID control where P, I, and D are coefficients for the proportion, integral, and derivative, respectively.
In the ADR system, the temperature must stabilize at 60 mK. The PID controller
sets the voltage across the magnet, allowing it to drive the temperature
back to the set point. A computer program is used to run the ADR and implement
the PID control.