PLC Ladder Diagram for a Sliding Mode Filtering Tracking Differentiator

Tracking input signal by providing its derivatives is important in control applications. However, input signal usually contains undesirable noise that may lead to system failure. On the other hand, in industrial environment, Programmable Logic Controllers (PLC) are still main digital controllers. Different from computers and MCUs, PLC employs a program language called Ladder Diagram, which maps the control logics through graphical symbols and blocks. This paper presents a ladder diagram for implementing a sliding mode filtering tracking differentiator on PLC to track input signal by removing noise. Experimental results validate the effectiveness of the presented method.