Motion control of underwater objects by using second order sliding mode techniques

In this chapter some recent results using a second order sliding mode methodology have been presented. This approach allows almost the same features of the first order sliding mode algorithms to be obtained in terms of simplicity, robustness and decentralisation of control structures, while eliminating the chattering phenomenon. The effectiveness of the relevant algorithm has been demonstrated experimentally on a prototype of an underwater actuation system based on opposite jets. The results appear promising for future generalisation to more complex underwater objects. The evaluation of the advantages of the proposed actuators with respect to traditional thrusters, briefly hinted at in this chapter, requires more systematic experimental as well as theoretical work and will be considered in future work.