PID control parameters optimization for temperature calibration laboratory

PID controllers are the most widespread types of controllers and are necessary for controlling furnaces and baths in temperature calibration laboratory. They are quite difficult to tune, but there are dozens of different tuning schemes, each working slightly better or worse depending on the type of system that is controlled; there is no perfect tuning scheme. One of the best known method is called the Ziegler-Nichols method. It works quite well on a large number of systems and does not require extensive system testing or measurement beforehand. Systems are described by non-linear differential equations and general solving is almost impossible. This is the main reason why the local linearization in the working temperature is needed. It leads to create of the PID parameters table for each measurement point. Investigated device was modeled in the Simulink environment and the theoretical behavior after application of the Ziegler-Nichols method was compared with the results for several other methods. These results was also compared to the measured data of the real behavior of the system. Based on the results comparison, there could be proposed a simple way to optimize PID control parameters of most of the furnaces and baths in the temperature calibration laboratory