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) Underwater 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 external disturbances and the unknown URV uncertainties. The performance of the ANLPID controller was evaluated by comparing the ANLPID controller with other existing works that are Nonlinear PID (NLPID) controller and Nonlinear Fractional PID (NLFOPID) controller. 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 controller and by 54.6479% compared to the NLFOPID controller.