A new method of AUV control based on RS-LSSVM for suppressing inevitable but overlooked coupling

AUV (autonomous underwater vehicle) is playing a more and more important role in the world. Usually AUV attitude control system is divided into the non-interfering pitch motion control and yaw motion control. The coupling between them due to nonzero roll angle is always overlooked. But the unwanted roll excursions are actually inevitable; they can contribute to poor balance, diving and steering performance. Aiming at suppressing the inevitable coupling effect, we put forward a new decoupling control method based on RS-LSSVM, where RS stands for "rough sets" and LSSVM stands for "least squares support vector machine". Section 1 of the full paper briefs the pitch-yaw model of AUV. Subsection 2.1 deals with RS theory and subsection 2.2 deals with LSSVM model. Fig. 2 shows the establishment of RS-LSSVM model. Section 3 is the key topic. The RS-LSSVM comprehensive decoupling controller model is shown in Figs. 3 and 4. Section 4 gives simulation results respectively for RS-LSSVM and standard PID on a certain type of AUV, and then compares them. The simulation results in Figs.5 and 6 and their analysis show preliminarily that the RS-LSSVM decoupling controller is effective for suppressing the coupling between pitch motion control and yaw motion control and that this controller provides high accurately and at the same time enhances greatly the operation rate, thus providing a new method for the precisely decupled control of AUV.