Tuning a PID controller appears easy, requiring you to find just three values: proportional, integral, and derivative gains. In fact, safely and systematically finding the set of gains that ensures the best performance of your control system is a complex task. Traditionally, PID controllers are tuned either manually or using rule-based methods. Manual methods are iterative and time-consuming, and if used on the hardware, can cause damage. Rule-based methods also have serious limitations: they do not support certain types of plant models, such as unstable plants, high-order plants, or plants with little or no time delay. In addition to tuning, PID control involves design and implementation challenges, such as discrete-time implementation and fixed-point scaling.
Using a four-bar linkage system as an example, this article describes a method that simplifies and improves the design and implementation of PID controllers. This method is based on two R2009b product features: the PID Controller blocks in Simulink® and the PID tuning algorithm in Simulink Control Design™