Design of an Aerial Manipulator with Active Moment Compensation
M.R. Ramidi (TU Delft - Mechanical Engineering)
Javier Alonso-Mora – Mentor (TU Delft - Mechanical Engineering)
Sihao Sun – Mentor (Universitat Zurich)
Tom Minten – Mentor (SpectX)
M. Wisse – Graduation committee member (TU Delft - Mechanical Engineering)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
Unmanned Aerial Manipulators (UAMs) have revolutionized industrial infrastructure inspection. But when a drone deploys an extended manipulator arm to carry dense Non-Destructive Testing (NDT) sensors, the payload severely shifts the system's Center of Gravity (CoG). This forward shift generates static pitch torques that can quickly overwhelm and saturate standard flight controllers.
To resolve this, this thesis presents the design, digital simulation, and experimental flight validation of a novel aerial manipulator. The architecture features a 1-Degree-of-Freedom (1-DOF) parallel linkage equipped with auxiliary tip motors. This system utilizes an Active Moment Compensation (AMC) strategy, in which the tip rotors generate dedicated vertical lift to continuously counteract the payload's gravitational torque, fundamentally decoupling the manipulator's reach from the primary quadrotor's stabilization limits. Before physical deployment, the control logic was validated in a high-fidelity Software-in-the-Loop (SITL) digital twin using ROS 2 and Gazebo Harmonic. Crucially, the PX4 Control Allocator was mathematically extended from a standard 4-rotor matrix to a custom 6-rotor geometry, enabling the autopilot to natively map thrust across the system.
Extensive parametric flight testing proved the core kinematic hypothesis: because the parallel linkage forces the tip-rotors to remain perfectly horizontal, the required compensation thrust is a mathematical constant, completely independent of the arm's pitch angle. Experimental data confirmed that the AMC architecture neutralizes extreme CoG shifts while preserving the dynamic thrust headroom required for stable flight. Additionally, vibration and telemetry analyses demonstrated that elevating the mechanism isolates it from the primary rotor downwash, reducing structural resonance and altering attitude control performance. By successfully de-risking this active-thrust architecture, this research provides a rigorously verified, scalable framework for deploying heavy industrial sensors at extended standoffs.