Distributed Fuzzy Optimal Fault-Tolerant Formation Control for Underactuated AUVs With Performance and Input Constraints

Marine operations of underactuated autonomous underwater vehicle (AUV) formations face the dual challenge of balancing control performance with energy efficiency while mitigating performance degradation caused by actuator faults. Toward this end, a distributed fuzzy optimal fault-tolerant formation control method with prescribed performance is proposed. First, a globally prescribed-time performance function with adaptive adjustment is designed, and the formation errors are transformed accordingly, thereby avoiding the contradiction between input constraints and prescribed performance, as well as eliminating initial error restrictions and singularity problems. Then, based on the reconstructed dynamics and an error dynamic system with an affine form, an optimal formation controller with a single-critic structure and without explicit dynamics is derived by combining a generalized fuzzy hyperbolic model (GFHM) and the Bellman equation. In this process, a modified nonquadratic cost function is developed to transform actuator faults, environmental disturbances, and asymmetric input constraints into an optimal control problem for a nominal system. Finally, a parameter update law that does not require initial admissible control is designed. Compared with previous methods, the proposed approach makes use solely of error feedback signals to achieve overall optimal fault-tolerant formation control while ensuring the transient and steady-state performance of formation control under input constraints. Theoretical analysis proves the stability of the closed-loop system, and the formation errors can remain within prescribed boundaries. Simulation results demonstrate the validity and advantages of the proposed method.