Thrust Enhancement and Degradation Mechanisms due to Self-Induced Vibrations in Bio-inspired Flying Robots

TL;DR

This study investigates how self-induced vibrations affect thrust in bio-inspired flapping robots, revealing that vibrations can either degrade or enhance thrust depending on the robot's wing mechanism.

Contribution

The paper provides experimental and visual analysis of vibration effects on thrust in two different bio-inspired flapping robots, highlighting mechanisms of thrust enhancement and degradation.

Findings

Vibrations reduce thrust in two-wing robots due to jet perturbation.

Vibrations enhance thrust in four-wing clap-and-peel robots by amplifying the clapping effect.

Flow visualization shows different flow perturbations caused by vibrations in the two robot types.

Abstract

Whenever a flapping robot moves along a trajectory it experiences some vibration about its mean path. Even for a hovering case, a flier experiences such vibration due to the oscillatory nature of the aerodynamic forces. In this paper we have studied the effect of such vibration on hovering. We used two setups to measure thrust force generated by flapping robots. One involving loadcell, which does not allow any kind of vibration. The other one involves a pendulum which allows vibration at a particular direction. We used two different flapping robots; one is a traditional flapping robot with two wings and the other one is a four wings robot which exploits clap and peel mechanism to generate thrust. We observed that the loadcell setup measures more thrust for the two wings model than the pendulum setup. The opposite trend was observed for the four wings model. We measured the vibration induced velocity using motion capture system. We used well known aerodynamic models to observe the effect of the vibration during the flapping cycle. To gain physical insight into the vibration affected flow field, we used smoke flow visualization at different instances during the flapping cycle. It revealed that the perturbation ebbs a jet effect in case of the two wings which leads to its adverse effect for thrust generation. On the contrary the perturbation enhances the clapping effect for the four wings robot, resulting favorable for thrust generation.