Sliding Mode Control of an Underwater Vehicle with Multi-Mode for Ultra-Long Tunnels

To ensure high-power operation of underwater vehicle in ultra-long tunnels, this paper investigates an underwater vehicle that can switch modes of operation. The multi-modes underwater vehicle can provide sufficient power to complete high-power operations in ROV (Remotely Operated Vehicle) mode, achieve ultra long-range cruising in AUV (Autonomous Underwater Vehicle) mode and when it switches to ARV (Autonomous Remotely-operated Vehicle) mode, it only communicates through microfiber fibers. SMC (Sliding Mode Control) is adopted for motion control of the underwater vehicle. In order to suppress system chattering, improve control effectiveness, and enhance control accuracy, a saturation function is used instead of the switching function of sliding mode control. The control law is designed using a dual loop control method. The outer loop is a position subsystem, and a virtual sliding mode control input is used to generate intermediate command signals and transmit them to the inner loop attitude subsystem. The inner loop tracks the intermediate command signals through sliding mode control law. Simultaneously, adaptive laws are designed to estimate external interference.