A Cascaded Nonlinear Heading Control with Thrust Allocation: An Application on an Underactuated Remotely Operated Vehicle

In this paper, we propose a new pipeline tracking control of an underactuated remotely operated vehicle (ROV) based on a thruster allocation and a nonlinear PD heading control for inner and outer loops respectively. The thruster allocation control without constraint uses the vehicle´s velocity feedback to detect the change in thrust required for the thrusters used in ROV´s maneuvering. Generalized ROV models for decoupled horizontal and vertical plane motions are derived that based on small roll and pitch angles that are self-stabilizing during operations. When compared with the Proportional-Derivative (PD) controller for all motions, the proposed cascaded controller is proven to render the tracking error dynamic globally k-exponentially stable with a lower control effort needed. Computer simulations are performed on these controllers and shown to be robust against parametric uncertainty