New UAV Control Framework Ensures Stable Contact During Aerial Physical Interaction

Researchers Abhimanyu Khadga, Abhinav Sinha, and Shashi Ranjan Kumar introduce a control-theoretic framework for contact-persistent full actuation in unmanned aerial vehicles (UAVs). Traditional certification of fully actuated UAVs relies on rank conditions of the control-allocation matrix or free-flight tracking performance, which is insufficient for aerial physical interaction tasks. During sustained contact, part of the available wrench is consumed by the interaction task, leaving only a residual wrench for stabilization and maneuvering. The paper defines feasible wrench sets under actuator limits, residual wrench sets under task loading, and residual authority margins that strengthen the usual rank-based notion of full actuation.

The main theoretical result shows that contact-persistent full actuation is equivalent to the interiority of the task wrench within the constrained feasible wrench polytope, with the residual authority radius being exactly the distance to the polytope boundary. The framework also introduces a signed residual-margin certificate for infeasible/boundary cases and a slack-maximizing allocation certificate. Numerical evaluation on an abstract tilted hexarotor demonstrates that full row rank alone does not imply feasible contact operation. Intermediate tilt angles preserve residual authority during pushing, while small or excessive tilts fail due to lateral-force deficiency or hover-margin loss. This work provides a rigorous tool for designing UAVs capable of sustained physical interaction.