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