Comparison between PID and Sliding Mode Controllers for Rotary Inverted Pendulum Using PLC

This research proposes the balancing control of the rotary inverted pendulum (RIP) by using PLC. The platform was designed and developed for PLC training kit, in order to enhance the learning a nonlinear control for stabilization problem. By using ST programming language, a modern PLC is capable to implement a robust control handling with complex task. In this work, OMRON PLC model CPIL-M30DTD which providing high-speed counter and high speed pulse output was used as main controller to provide real-time control. To compare the performance of stabilizing RIP, two controllers: PID and SMC control were designed and implemented in PLC. The optimal gain of PID controller was tuned by Ziegler Nichols first method, while SMC controller was designed based on system dynamic model. The conducted experiment result shows that the balancing performance was improved by SMC controller for 54.30%, even though PID controller provided lower oscillation result. The propose of SMC controller is to deal with an uncertainty in nonlinear system, while PID controller is to reduce the tracking error.