Impact Absorbing and Compensation for Heavy Object Catching With an Unmanned Aerial Manipulator

Maintaining stability after catching an object is essential for the flight safety of unmanned aerial manipulators (UAMs). Current research on UAM catching stationary or moving targets neglects the impact of the target and the introduced center of mass (COM) displacement. This letter proposes an approach to absorb the impact during the capture of fast-flying heavy targets by UAMs, ultimately reducing UAM movement. An angular momentum theorem-based fast target mass estimation algorithm is proposed to estimate the target mass within the limited catching time. With the estimated target mass, a mass compensated impedance controller for a brushless motor-based arm and a compensation algorithm for the UAM attitude controller are proposed. An innovative aspect of our approach is utilizing the estimated target mass to adjust the impedance controller and compensate for COM displacement, which enables effective absorption of the target's impact and reduces UAM movement. We validate our proposed approach through simulation and real-world experiments. The results demonstrate that our approach significantly reduces UAM body displacement after capturing fast-flying heavy targets, enhancing UAM's flight safety.