Adaptive integral back-stepping controller design for ROV with disturbance observer

The problem focusing on heading motion control of remotely operated underwater vehicle (ROV) is studied and adaptive integral back-stepping controller with nonlinear disturbance observer (NDO) is proposed in this paper. Taking advantage of the ability that nonlinear disturbance observer can estimate uncertainties and external disturbance exactly, combined back-stepping method, we can greatly reduce the influence of parameter uncertainties and external disturbances on the ROV system; meanwhile, in order to enhance the robust performance of the system, integral terms are added into the feedback loop; finally, adaptive item is added in order to estimate residual uncertainties and interference. Design process of the controller for ROV is described in detail; using Lyapunov stability criterion, global asymptotic stability and tracking error convergence are proved. Simulation experiments have shown that the controller can overcome and estimate factors such as external disturbance and model uncertainties, the system is able to track the desired trajectory accurately and has good robust performance.