Fixed-Time Leader-Following Formation Control of Fully-Actuated Underwater Vehicles Without Velocity Measurements

This paper is concerned with formation control of fully-actuated underwater vehicles (FUVs), focusing on improving system convergence speed and overcoming velocity measurement limitation. By employing the fixed-time control theory and command filtering technique, a full state feedback formation algorithm is proposed, which makes the follower track the leader in a given time with all signals in the system globally practically stabilized in fixed time. To avoid degraded control performance due to inaccurate velocity measurement, a fixed-time convergent observer is designed to estimate the velocity of FUVs. Then the authors give an observer-based fixed-time control method, with which acceptable formation performance can be achieved in fixed time without velocity measurement. The effectiveness and performance of the proposed method are demonstrated by numerical simulations.