An Adaptive Nonlinear PID Design for 6-DOF Underwater Robotic Vehicle

Abstract

An Adaptive Nonlinear PID (ANLPID) controller for six Degrees of Freedom (6-DOF) Under- water Robotic Vehicle (URV) model is proposed to solve the path tracking problem. The path tracking problem is mainly caused by external environmental disturbances and the unknown uncertainties of the URV model. The ANLPID controller is used to estimate both the exter- nal disturbances and the unknown URV uncertainties. The performance of the ANLPID controller was eval- uated by comparing the ANLPID controller with other existing works that are Nonlinear PID (NLPID) con- troller and Nonlinear Fractional PID (NLFOPID) con- troller. The system stability is proved by utilizing the Lyapunov function. At the end, the results obtained show the proficiency of the ANLPID controller, where the ANLPID controller improved the performance of the URV by 41.4185 % compared to the NLPID con- troller and by 54.6479 % compared to the NLFOPID controller.