Distributed Robust Prescribed Performance 3-D Time-Varying Formation Control of Underactuated AUVs Under Input Saturations and Communication Delays

In oceanographic mapping, underwater exploration, and military reconnaissance scenarios, it is necessary to deploy multiple autonomous underwater vehicles (AUVs) to cooperatively fulfill some operational tasks. In the presence of uncertain dynamics, time-varying ocean environmental disturbances, input saturations, and communication delays, this article innovatively solves the 3-D time-varying formation problem of underactuated AUVs by creating a data-driven motion state predictor (DDMSP), a modified super-twisting algorithm (STA), and a new auxiliary dynamic system (ADS). In lieu of the indirect way of handling the communication delays in most of the existing works, a novel way of directly handling them is proposed in this article with help of the created DDMSP. Based on the modified STA, a super-twisting extended state observer is constructed to accurately estimate the total disturbances lumped by the uncertain dynamics and disturbances. The ADS contributes to mitigating the adverse effect of input saturations. By virtue of the above, a novel distributed robust prescribed performance 3-D time-varying formation control law is developed, which ensures that the AUVs maintain the desired 3-D time-varying formation pattern, while presetting the time desired for the formation errors to reach and stay within the prescribed error tolerance band. Simulation studies on a group of AUVs demonstrate the remarkable performance of our developed formation control law.