Optimal output tracking control for autonomous underwater vehicles

A nonlinear discrete-time system model is used for autonomous underwater vehicles (AUV) and the optimal output tracking control (OOTC) is designed. By introducing a sensitivity parameter and expanding around it, the original nonlinear two-point boundary value (TPBV) problem led by the OOTC problem is transformed into a series of linear TPBV problems containing known low-order nonlinear terms. Algorithm of nonlinear expanding terms is obtained and substituting them into the recursion formula of adjoint vector equations, the OOTC law consisting of linear terms and a nonlinear compensation term can be approximately obtained. A simulation example from AUV is employed to test the validity of the presented algorithm.