The aim of this paper is to develop a fuzzy iterative sliding mode control (FISMC) scheme for special autonomous underwater vehicles (AUVs) on three-dimensional (3D) path following. In this paper, the characteristics of the AUV are considered, which include a large scale, large inertia, and high speed. The FISMC controller designs iterative sliding mode surfaces by using a hyperbolic tangent function to keep the system with fast convergence and robust performance. At the same time, system uncertainties and environmental disturbances are taken into account. The control algorithm introduces fuzzy control to optimize the control parameters online to enhance the adaptability of the system and inhibit the chattering of the actuators. The performance of the proposed FISMC is demonstrated with numerical simulations.
This article proposed a novel method for submarine hovering control implement by ballast tanks based on L1 adaptive theory. The ballast tanks are able to provide submerge/emerge force by let in/out ballast tank water, and therefore adjust submarine position and altitude when low-speed maneuver largely limits rudder effect. After formulate and analysis models of ballast tanks as well as submarine dynamic, control scheme is determined as cascaded controller system. L1 adaptive theory is adopted for outer loop control, to deal with the nonlinearity and uncertainties of model, as well as environmental disturbance in hovering condition for the first time. Robustness of control system is tested through simulations based on Simscape. Large impact force is exerted on submarine to simulate missile launching and test restoring ability of ballast tanks control. Simulation results demonstrated that the submarine is able to maneuver and response precisely, despite of sudden impact.
In this paper, the research contents are mainly focused on the technology of the underwater wheeled vehicle speed control. For providing a passive towed underwater wheeled vehicle with accelerating, uniform motion and decelerating capability which can simulate an underwater navigation environment for the carried unit, we devised a novel open-type hydraulic flexible towing system. Combining the hydrodynamic model of the vehicle and the hydraulic mechanism model, the dynamic characteristics of the novel towing system are studied by computing simulation. Aiming at the force coupling character of double driving hydraulic winches, a master-slave synchronization control strategy is proposed. Then, in view of the flexible towing system features, i.e., strong coupling, nonlinear, time-varying load, and environmental constraints, a real speed controller based on fast terminal sliding mode control theory is designed and manufactured. To verify the effectiveness of the controller, a hardware-in-the-loop simulation test is carried out on the strength of a semiphysical simulation platform based on Matlab/Simulink and VxWorks real-time system. The experiment results show that the speed controller based on fast terminal sliding mode control has excellent effect on rapidity, stability, and anti-interference characteristics.
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