Allocation for Omnidirectional Aerial Robots: Incorporating Power Dynamics

2024-12-20

arXiv.org

AI Summary

Over-actuated actuator coordination for tiltrotor aerial robots remains challenging under thrust-vectoring and body-attitude decoupling, particularly due to singularities in conventional geometric allocation. Method: This paper proposes a differential allocation method incorporating actuator dynamics—replacing geometric allocation with a singularity-free formulation—and introduces, for the first time, a coupled servo-rotor dynamic model integrated with rotor saturation curves to enable on-demand motor activation/deactivation and load balancing; redundancy optimization further ensures real-time dynamic trajectory tracking. Results: Experimental validation demonstrates an angular velocity tracking bandwidth of 4 rad/s (a 43% improvement), significantly enhanced robustness in oscillatory trajectory tracking, simplified controller parameter tuning, and improved energy efficiency utilization.

Technology Category

• Search and Optimization: Mixed Discrete/Continuous Search
• Intelligent Robots: Learning & Optimization for ROB
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• User Modeling, Personalization and Recommendation: Accountability, Transparency, and Ethics for personalization

Abstract

Tilt-rotor aerial robots are more dynamic and versatile than their fixed-rotor counterparts, since the thrust vector and body orientation are decoupled. However, the coordination of servomotors and propellers (the allocation problem) is not trivial, especially accounting for overactuation and actuator dynamics. We present and compare different methods of actuator allocation for tilt-rotor platforms, evaluating them on a real aerial robot performing dynamic trajectories. 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 typical of the geometric solution. We expand it by incorporating actuator dynamics and introducing propeller limit curves. These improve the modeling of propeller limits, automatically balancing their usage and allowing the platform to selectively activate and deactivate propellers during flight. We show that actuator dynamics and limits make the tuning of the allocation not only easier, but also allow it to track more dynamic oscillating trajectories with angular velocities up to 4 rad/s, compared to 2.8 rad/s of geometric methods.

Problem

• Solve tiltrotor allocation considering overactuation and dynamics
• Develop differential allocation avoiding singularities using redundancy
• Model propeller dynamics for speed control and selective deactivation

Innovation

• Differential allocation avoids singularities using redundancy
• Incorporates actuator and propeller power dynamics
• Normalizes allocation for faster trajectory tracking