Fixed-Time Control of a Novel Thrust-Vectoring Aerial Manipulator via High-Order Fully Actuated System Approach
Zhan Li, Yipeng Yang, Xinghu Yu, Cuiyu Liu, Okyay Kaynak, Huijun Gao
Abstract
Unmanned aerial manipulators (UAMs) extend the operational reach of unmanned aerial vehicles (UAVs), yet are often limited by the underactuation of traditional UAV platforms, restricting the workspace of their end-effectors. This article introduces an overactuated UAM system comprising a biaxial-tilting thrust-vectoring quadrotor coupled with a serial manipulator. This configuration offers superior controllable performance, an expanded manipulator workspace, and robust disturbance rejection compared to conventional underactuated UAMs. To mitigate practical uncertainties and disturbances–including model imprecision, environmental factors, changing loads, and the coupling wrenches between the UAV and manipulator–a fixed-time (FxT) controller and a FxT disturbance observer are developed, leveraging a high-order fully actuated (HOFA) control strategy. The implicit Lyapunov function (ILF) approach is employed for stability analysis, offering a streamlined proof of convergence. Simulations and flight tests affirm the system's trajectory tracking precision, with positional and attitudinal accuracies within <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1\;\text{cm}$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1^{\circ }$</tex-math></inline-formula> , respectively.