Variable Structure Control via Coupled Surfaces for Control Effort Reduction in Remotely Operated Vehicles

In this chapter, a Variable Structure Control law is presented and applied to solve the tracking problem for a Remotely Operated Vehicle. Unlike the classical Sliding Mode Control, which is composed by a single sliding surface, the proposed control law presents two coupled sliding surfaces. It follows that the state space can be divided into two spaces, namely one between the surfaces and one outside them. In the region outside the surfaces, the controller is designed similarly as for the classical Sliding Mode Control, while, inside the area, the system is in free motion. It follows that the control effort is null for some time intervals, hence a reduction of control efforts is possible. In order to test the performances of the proposed technique, exhaustive simulations are made for a Remotely Operated Vehicle, and compared with classical Sliding Mode Control, where linear sliding surfaces are taken into consideration for both cases, combined with a bang-bang-type control logic. Simulation results show that, for the tracking problem, the proposed Variable Structure Control technique performs better both in terms of performances (estimated with the Integral of Absolute Error) and energy consumption (estimated with a related cost function).