Soft Arm-Motor Thrust Characterization for a Pneumatically Actuated Soft Morphing Quadrotor

TL;DR

This paper experimentally characterizes the thrust and deflection behavior of a soft, pneumatically actuated quadrotor's arms, accounting for complex nonlinear interactions and downwash effects to improve control accuracy.

Contribution

It provides the first detailed experimental analysis of soft arm thrust and deflection in a morphing quadrotor, including downwash disturbance effects.

Findings

Downwash significantly affects arm deflection and thrust.

Soft arms exhibit nonlinear behavior due to pneumatic actuation.

Characterization enables better control strategies for soft drones.

Abstract

In this work, an experimental characterization of the configuration space of a soft, pneumatically actuated morphing quadrotor is presented, with a focus on precise thrust characterization of its flexible arms, considering the effect of downwash. Unlike traditional quadrotors, the soft drone has pneumatically actuated arms, introducing complex, nonlinear interactions between motor thrust and arm deformation, which make precise control challenging. The silicone arms are actuated using differential pressure to achieve flexibility and thus have a variable workspace compared to their fixed counter-parts. The deflection of the soft arms during compression and expansion is controlled throughout the flight. However, in real time, the downwash from the motor attached at the tip of the soft arm generates a significant and random disturbance on the arm. This disturbance affects both the desired deflection of the arm and the overall stability of the system. To address this factor, an experimental characterization of the effect of downwash on the deflection angle of the arm is conducted.