Nonlinear PID Dead-Zone Compensation for High-Fidelity Wave-Motion Simulation in Marine Floating Photovoltaic Systems

Floating photovoltaic (FPV) systems experience continuous attitude variations under wave excitation, and accurate laboratory reproduction of such motion is essential for evaluating electrical and mechanical performance. However, push-rod actuators typically used in FPV simulators suffer from asymmetric dead-zone voltages during direction reversal, causing stagnation, phase lag, and peak clipping when controlled with conventional PID. This letter identifies this overlooked limitation and proposes a lightweight nonlinear PID controller with direction-dependent bias compensation that forces the PWM output to instantaneously surpass the dead-zone thresholds. Implemented on an STM32F407, the method eliminates reversal-induced pauses and enables smooth sinusoidal tracking. Experiments show that the proposed controller reduces phase lag from 0.176 s to 0.061 s (65.3%) and the sum of squared errors from 12.75 to 1.37 (89.3%), representing a substantial improvement over linear PID. The approach is computationally inexpensive and broadly applicable to actuator systems exhibiting dead-zone characteristics.