Comparative analysis of PID and cascade PID controllers for path-following in unmanned surface vehicles: experimental and numerical simulation

Path following as the most critical behavior for an Unmanned Surface Vehicle (USV), is a motion that requires high precision and stability. Many studies on the USV path following focus on improving a single algorithm or designing various advanced controllers, but they lack a comprehensive comparison and evaluation of the controller's performance through physical experiments. Unlike previous studies focusing solely on simulations or individual control improvements, this paper, for the first time, investigates two widely used controllers in single-degree-of-freedom USV path following, the cascade PID controller and the PID controller, by comparing their performance through both simulations and experiments. Through our analysis, the cascade PID controller demonstrates superior performance compared to the PID controller in response speed, overshoot, and steady-state error. It is found that the starting position of the USV in the actual experiments influenced the results in this work, which is often ignored in prior works.