STABILITY ANALYSIS OF A UAV EQUIPPED WITH A ROBOTIC ARM

Abstract

The paper presents a detailed stability analysis of an unmanned aerial vehicle (UAV) equipped with a 2-DOF robotic arm designed for grasping and manipulating different payloads. UAV-manipulators have got increasing attention due to their ability to perform complex manipulation tasks while flying. Despite the advantages, these systems face various challenges, and their control strategies need to be examined to ensure reliable and stable performance in such dynamic conditions. To address these challenges, the dynamics of the UAV-manipulator system are discussed in the paper. The manipulator's kinematics are modeled according to the Denavit-Hartenberg convention. The full system dynamics are derived using the Euler-Lagrange method, considering both UAV and robotic arm dynamics with their coupled interactions.  A key contribution of this work is the formulation of the inertia matrix of the system as a constant nominal component and a time-varying uncertainty as a result of the effects of manipulator motion and object interaction. This separation enables a more structured and detailed analysis of the system's stability under changing robot configurations and payloads. To support the analysis, a Matlab/Simulink model of the UAV-manipulator system is developed based on the derived symbolic dynamics. The simulation model allows to test various manipulation scenarios and helps to monitor the key indicators of stability such as the system's response, center-of-mass behavior, and the effects of payload variations on the system’s stability. The results emphasize the impact of the manipulator's configuration and the payload on the overall dynamics of the system. The proposed framework serves as a foundation for the future development of adaptive or data-driven control strategies that can address the dynamic uncertainties of the UAV-manipulator system.