Experimental Optimization of PLC-Integrated Multi-Loop PID Control for a Three-Level Electro-Hydraulic Elevator Using PSO and Cheetah Optimizer

This study presents the design, modeling, and experimental evaluation of a three-level electro-hydraulic elevator system controlled by a Delta DVP-20SX2 Programmable Logic Controller (PLC) equipped with an integrated Proportional–Integral–Derivative (PID) module. The PLC, programmed in Ladder Logic using ISPSoft 2.46, regulates cabin motion across all three levels. A detailed MATLAB/Simulink model was developed, incorporating three PID controllers: one for displacement regulation via a proportional directional control valve and two for dynamic pressure regulation using a proportional pressure relief valve. Conventional PID parameters were initially tuned using the trial-and-error method based on time-domain performance indices and subsequently optimized using Particle Swarm Optimization (PSO) and the Cheetah Optimizer (CO). The optimized controllers are referred to as PSO-PID and CO-PID, respectively. The error standard used for the electro-hydraulic elevator control system is the Integral Time-weighted Absolute Error (ITAE) type. This study addresses the need to improve dynamic performance and control accuracy in electro-hydraulic elevator systems under maximum load conditions. Experimental results obtained under a 30 kg load for the displacement response showed that PSO-PID reduced rise time by 36.8% and settling time by approximately 37.2% while improving steady-state accuracy by nearly 80% compared with the conventional PID. The CO-PID controller further improved performance, achieving additional reductions of 13.6% in rise time and 13.8% in settling time relative to PSO-PID, as well as decreasing steady-state error by 37.5%. Overall, CO-PID achieved substantial reductions in rise and settling times (up to 45.4% and 45.7%, respectively) and improved steady-state accuracy by nearly 87% compared with the traditional PID. In pressure control loops, PSO-PID reduced settling time by up to 12.8%, whereas CO-PID achieved up to 16.4% faster stabilization relative to the conventional PID. The experimental results were in agreement with the developed MATLAB/Simulink model, confirming the high accuracy of the simulation in representing the system dynamics. These findings demonstrate the superior responsiveness, stability, and efficiency of the CO-PID controller for electro-hydraulic elevator applications.