Implementing Incremental PID Control Algorithm Using MATLAB's S-Function in C

In this article, we will demonstrate how to create C-language S-functions in MATLAB to implement an incremental PID control algorithm. We will thoroughly examine the algorithm's mathematical foundation and computational procedure, while providing practical code examples that illustrate key implementation aspects including error calculation, proportional-integral-derivative term updates, and output increment computation. The implementation addresses the core algorithm components: calculating the current error (e(k)), determining the proportional term (Kp×[e(k)-e(k-1)]), integral term (Ki×e(k)), and derivative term (Kd×[e(k)-2e(k-1)+e(k-2)]), then summing these components to produce the control increment. We will discuss the algorithm's application in control systems, focusing on practical parameter tuning strategies using techniques like Ziegler-Nichols method and optimization approaches for different system dynamics. Code implementation details will cover essential S-function callback methods such as mdlInitializeSizes for setting input/output ports, mdlDerivatives for handling continuous states, and mdlOutputs for computing the control signal. The article will also demonstrate how to handle discrete-time implementation using mdlUpdate for state management. Through this comprehensive guide, you will gain deep understanding of incremental PID control algorithm implementation and be able to apply it to your control systems to enhance performance metrics including response speed, stability, and disturbance rejection capabilities.