  Position and speed control of the torpedo present a real problem for the
actuators because of the high level of the system non linearity and because of
the external disturbances. The non linear systems control is based on several
different approaches, among it the sliding mode control. The sliding mode
control has proved its effectiveness through the different studies. The
advantage that makes such an important approach is its robustness versus the
disturbances and the model uncertainties. However, this approach implies a
disadvantage which is the chattering phenomenon caused by the discontinuous
part of this control and which can have a harmful effect on the actuators. This
paper deals with the basic concepts, mathematics, and design aspects of a
control for nonlinear systems that make the chattering effect lower. As
solution to this problem we will adopt as a starting point the high order
sliding mode approaches then the PID sliding surface. Simulation results show
that this control strategy can attain excellent control performance with no
chattering problem.
