Adaptive sliding modes based steering protocol design for underwater vehicles with partially functional actuators

This paper presents a simple steering control algorithm for an underwater vehicle which is an example of nonholonomic drift free systems. The method is based on adaptive sliding mode control technique which does not require the model conversion into chain form. In the proposed steering control algorithm, some suitable Hurwitz sliding surfaces and a Lyapunov function are selected. The adaptive laws are derived while keeping Lyapunov function strictly negative to guarantee the stability of the closed loop system. The proposed method is tested on two different underwater vehicle models; in the first model all actuators are working, and in the second model one actuator is not working. The controllability Lie Algebra of the first model when all actuators are working, contains Lie brackets of depth one while the second model when one actuator fails contain Lie brackets of depth one and two. The effectiveness of the proposed method is verified through simulation studies.