Globally finite-time stable tracking control of underactuated UUVs

This paper addresses the problem of trajectory tracking control for underactuated unmanned underwater vehicles (UUVs) with model parameter perturbation and constant unknown current in the horizontal plane. The globally finite-time tracking control strategy is adopted driving an UUV to track a predefined trajectory. Firstly, the horizontal trajectory tracking guidance laws are established by the virtual vehicle method, where the tracking error equations are derived. Secondly, the kinematic controllers are designed with equivalent control of the proportional-integral-derivative sliding mode control (PID-SMC). Thirdly, two dynamic controllers, including a speed controller and a steering controller, are designed by resorting to a first-order sliding mode surface and a second-order one, respectively. It is well proved that the proposed strategy can guarantee global convergence of all tracking errors within finite time. Simulations show that the control laws can achieve strongly robust and preferably control performance for the horizontal trajectory tracking control in the presence of the mode parameter perturbation and constant unknown current.