Yaw control torque generation for a hovering robotic hummingbird

Ali Roshanbin,André Preumont

doi:10.1177/1729881418823968

Ali Roshanbin, André Preumont

Open Access

https://doi.org/10.1177/1729881418823968

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Abstract

This study describes the design, development, and flight tests of a novel control mechanism to generate yaw control torque of a hovering robotic hummingbird (known as Colibri). The proposed method generates yaw torque by modifying the wing kinematics while minimizing its influence on roll and pitch torques. To achieve this, two different architectures of series and parallel mechanisms are investigated; they are mathematically analyzed to investigate their behavior with respect to cross-coupling effects. The analysis is verified by measuring the control torque characteristics. The efficacy of the proposed method is also explored by flight experiments.

Highlights

In the parallel architecture of the control mechanism implemented in Colibri, the yaw torque is achieved by introducing different inputs to the two linear actuators responsible for the pitch input; it is not subject to the kinematic coupling discussed above and it demonstrated some stable and successful flights
Two control mechanism architectures have been considered to modify the wing kinematics by moving the control bars, a series architecture where the yaw control servo is mounted on the output of the pitch servo and a parallel one where two linear servos control simultaneously the pitch and yaw axes
The yaw torque is manipulated by differential drag produced between the right and the left wings

Summary

Introduction

Animals with hovering capability such as hummingbirds and insects must generate sufficient lift to remain aloft, they must manipulate flight forces.[1,2] they are known to use their tail[3,4] (in hummingbird) and their legs and abdomen (in insects) as control surfaces during flight,[5,6] they steer and maneuver primarily by modifying wing kinematics and altering wing motions.[7,8]In the last decade, some engineers and researchers have developed robotic vehicles that mirror some of the basic wing kinematics of what their natural counterparts do.Some of the main techniques inspired from nature to achieve this are the angle of attack (AOA) modification (wing rotation and wing twisting modulation),[9,10,11] flapping plane tilting,[12,13] split cycle flapping,[14,15,16,17,18,19,20] flapping amplitude variation[13,17] and variable flap stroke centering.[17,21]Few researchers have successfully demonstrated the controlled flight of a hovering tailless twin-wing robot with the controlled heading capability. The two control mechanisms presented here (series and parallel design) are equipped with three conventional micro servos for controlling the position of the wing root bars; one rotary for roll and two linear servos for pitch and yaw actuation.

Results

Conclusion