Multirotors maintain control authority during contact with walls
Residual Wrench Certification and Margin-Aware Control Synthesis for Aerial Physical Interaction
Robotics
Summary
Flying drones that gently touch walls while hovering can lose control when their motors hit limits. The authors found a way to check how much control authority remains after the drone pushes against a wall. They use math to ensure the drone stays within safe control commands and can adjust the drone’s movements accordingly. They tested these ideas in simulations comparing drone designs and showed how their method predicts when control is lost.
What this means in practice
- •For drone developers: Ensure drones maintain safe and reliable control when physically interacting with surfaces like walls during hover.
- •For robot control engineers: Design controllers that adjust commands to respect actuator limits while preserving control margins in contact tasks.
Authors
Abhimanyu Khadga, Abhinav Sinha, Shashi Ranjan Kumar
Abstract
We develop a task-relative framework for certifying residual wrench authority after hover and contact loading in multirotors with bounded actuators. Using convex geometry, we derive signed margins for prescribed convex reserves, including Euclidean balls and weighted ellipsoids. We obtain computable reserve certificates from actuator-interiority bounds to support slack-maximizing allocation. To preserve the required reserve, we propose command projection onto a tightened feasible set. We then connect the available reserve to structured gain synthesis and certify a local tracking region that respects actuator limits. Within this region, we establish nominal exponential convergence and robust ultimate boundedness. For the prescribed task and morphology family, we show that the optimized octarotor attains a larger margin than the optimized hexarotor at equal total thrust. We evaluate the proposed framework in closed-loop simulations of sustained rigid-wall contact using a fixed-geometry octarotor and a variable-tilt quadrotor with matched installed thrust. The quadrotor's local certificate admits a higher normalized push limit for the prescribed task family. In tests beyond the realizability boundaries, we observe the predicted loss of authority through rotor-thrust limits for the octarotor and tilt-servo limits for the quadrotor.