Continuum elastic dynamic model for variable stiffness soft aerial robots with morphing capabilities

Abstract

Leveraging the use of flexible adaptive materials in aerial robots expands their flight capabilities and potential applications. Adaptation of morphology is key to expanding landing possibilities and accessing narrow confined spaces, as well as to increase flight efficiency. These compliant bio-inspired designs also ensure safe interaction with humans and the environment. Recent scientific advancements have been made in flapping or fixed-wing aerial robots, although hover capabilities remain limited. However, the application of flexible adaptive materials to multirotors, with an adaptable number of arms, shows promising potential for agile perching, dynamic grasping, multimodal locomotion, navigation through narrow channels, and high-speed fully-actuated forward flight. The main bottleneck lies in modeling, sensorization and control of these flexible structures. Accurate deformation estimation is crucial for understanding rotor thrust vectors and for managing the non-linear material behaviors during morphing at both high and low control levels. This work introduces a novel continuum dynamic model for variable stiffness soft aerial robots with morphing capabilities. The model is based on local constant curvature assumptions and incorporates nonlinear rotational inertias, allowing for the integration of fundamental boundary conditions such as rotor thrust and tendon-based actuation. This contribution is essential for achieving model-based control of the large deformations required in the aforementioned applications, as previous experimental static models have significant limitations. Furthermore, the development of a simulation environment, to assess the viability of these maneuvers depending on the multiple arm configurations, preserving equilibrium in the forces and moments acting on the UAV, is of paramount importance. The model’s experimental validation involves tracking the deformations of flexible arms using vision techniques morphing maneuvers. Regarding the upcoming conference, the ultimate objective is to make further progress in accomplishing the proposed morphing maneuvers using the presented model.