Sliding mode control of a servo system in LabVIEW: Comparing different control methods

Abstract

The main contribution of this paper is to present the efficiency of LabVIEW in simulating and controlling a servo system with conventional methods (PI and PID control), as well as sliding mode control (SMC). The control of an actual system with LabVIEW and NI hardware provides an efficient implementation platform, using both LabVIEW’s graphical programming and the text-based m-file language MathScript RT. Both programming environments and the connection to NI hardware are relatively easy to use, therefore, ideal for education. The graphical “coding” can help novice users to see through their algorithms. However, the mathematical background of sliding mode control is difficult compared to conventional PID control; the SMC implementation for practical uses can be quite simple, as the presented example demonstrates. The first didactic step is a simulation with the Control Design and Simulation, as well as MathScript RT Modules. Then a myRIO Student Embedded Device is used to control a real servo system. LabVIEW code can be compiled to run on computers, (soft) real-time targets, and FPGAs (hard real-time targets), so students can easily and quickly step up to real industrial measurement and control problems without the need to learn new programming environments.