This article contains a continuous-time optimal and adaptive control s
cheme for underwater vehicles moving in 6 d.o.f. The control scheme is
an modification of the algorithm of Johansson. The algorithm is optim
al in the sense that it minimizes the state errors and the forces whic
h contribute to the vehicle's kinetic energy that is spent to correct
these errors. The performance index also penalizes the quadratic track
ing errors proportional to the rate of energy dissipated from the syst
em as an effect of damping.