Allocation for Omnidirectional Aerial Robots: Incorporating Power Dynamics

TL;DR

This paper introduces three novel allocation methods for tilt-rotor aerial robots, incorporating actuator and power dynamics to improve control and maneuverability during dynamic flights.

Contribution

It extends geometric allocation into differential allocation, models actuator dynamics, and enables propeller power management for enhanced flight performance.

Findings

Differential allocation avoids singularities and uses platform redundancy.

Incorporating actuator dynamics allows for faster trajectory tracking.

Propeller power management enables selective turning off during flight.

Abstract

Tilt-rotor aerial robots are more dynamic and versatile than fixed-rotor platforms, since the thrust vector and body orientation are decoupled. However, the coordination of servos and propellers (the allocation problem) is not trivial, especially accounting for overactuation and actuator dynamics. We incrementally build and present three novel allocation methods for tilt-rotor aerial robots, comparing them to state-of-the-art methods on a real system performing dynamic maneuvers. We extend the state-of-the-art geometric allocation into a differential allocation, which uses the platform's redundancy and does not suffer from singularities. We expand it by incorporating actuator dynamics and propeller power dynamics. These allow us to model dynamic propeller acceleration limits, bringing two main advantages: balancing propeller speed without the need for nullspace goals and allowing the platform to selectively turn off propellers during flight, opening the door to new manipulation possibilities. We also use actuator dynamics and limits to normalize the allocation problem, making it easier to tune and allowing it to track 70% faster trajectories than a geometric allocation.