Underactuated control for an X4-AUV using partial linearization and attitude linearization

An autonomous underwater vehicle with four thrusters is reexamined from the viewpoints of derivation of a time-varying model. First, a bilinear model can be derived without depending on a chained form transformation, instead depending on partial linearization in inputs and on linearization of partial attitudes. Next, it can be transformed into a time-varying system that includes partially discontinuous states, and then an exponentially stabilizing method can be applied to its model to solve a stabilization problem. Some numerical simulations are conducted to demonstrate the effectiveness of the proposed method.