Design of control system for lift-sliding stereo garage based on S7-1215C and fuzzy PID algorithm

Urban parking shortages have become a pressing issue in China due to the rapid increase in private car ownership. To address these space constraints, automated multi-story garages are widely adopted because they save land, offer high vehicle capacity, and provide flexible layouts. This paper presents the design of a modular automated parking system controlled by a Siemens S7-1215C PLC. A major challenge in these mechanical systems is the massive weight variation during vertical lifting. To handle this, we integrated a fuzzy PID algorithm into the core control logic to improve the smoothness and response speed of the lifting motor. Rather than executing computationally intensive floating-point operations online, an offline-generated 2D look-up table, derived from fuzzy reasoning, is stored directly within the PLC. This ensures high-speed execution without slowing down the CPU or delaying safety interlocks. The designed module features a three-level, three-column structure with seven parking spaces and an HMI touchscreen for live monitoring. Simulation tests show that the proposed fuzzy PID strategy significantly outperforms traditional fixed-parameter methods. Under a heavy 2500 kg payload, the traditional PID controller exhibits a dangerous overshoot of 28.45%. In contrast, the proposed offline-computed fuzzy PID dynamically adjusts the control gains, achieving a theoretical zero-overshoot trajectory (0.00%) and reducing the settling time from 8.72 to 3.15 s.