Prescribed-Time Fault-Tolerant Formation Control for Collision-Free Unmanned Helicopters: A High-Order Fully Actuated System Approach
Qingyi Liu, Ke Zhang, Bin Jiang, Jinfa Xu
Abstract
This article investigates the prescribed-time fault-tolerant formation tracking problem in multiple unmanned helicopters subject to the both gain and bias actuator faults. In contrast to the existing results separating the under-actuated model into an outer-loop and an inner-loop subsystems on the whole, three high-order fully actuated subsystems are derived for design convenience at first. Subsequently, a prescribed-time fault estimation observer is developed to approximate the subsystem states and lumped faults, which can be completed within a user-preassigned time regardless of the initial observation conditions. Such a convergence time can also determine the relevant parameters to some extent. Afterwards, we incorporate the high-order fully actuated system approach into the prescribed-time fault-tolerant formation control protocol design procedures, to eliminate the influence of failures and preserve the target geometric pattern, in which an artificial repulsive potential function is utilized to avoid collisions among the followers on <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathbf {xoy}$</tex-math></inline-formula> -plane. In this manner, the prescribed-time property and the higher tracking accuracy can be accomplished. Finally, simulation results are presented to prove the reliabilities and benefits of the algorithm.