The nonlinear suboptimal diving control of an autonomous underwater vehicle

This work proposes a nonlinear suboptimal diving control scheme for autonomous underwater vehicles (AUVs) in presence of hydrodynamic parameter uncertainties and disturbance. The controller is designed via the state-dependent Riccati equation (SDRE) method that regulates the system´s states by minimization of the related quadratic cost function. To compensate the system´s restoring force (gravity/buoyancy), the common SDRE control law is supplemented with a discontinuous control law analogous to sliding surface notion. We applied the proposed controller to a well-known AUV model (REMUS). Simulation results demonstrate the effectiveness of the proposed controller under system´s parameter uncertainties and disturbance with appropriate regulation and tracking performance.