Analysis of hovering flight stability of an insect-like flapping-wing robot in Martian condition

• Published in: Aerospace science and technology Vol. 152; p. 109371
• Main Authors: Nguyen, Khanh, Ha, Giheon, Kang, Taesam, Park, Hoon Cheol
• Format: Journal Article
• Language: English
• Published: Elsevier Masson SAS 01.09.2024
• Subjects: Computational fluid dynamics; Flight dynamics; Hovering; Low gravity; Low-air-density; Mars; Stability derivatives; Mars; Computational fluid dynamics; Low gravity; Stability derivatives; Hovering; Low-air-density; Flight dynamics
• ISSN: 1270-9638
• DOI: 10.1016/j.ast.2024.109371

•Scaling the density and gravity, the hovering flapping frequency on Mars is required to be 113.48 Hz, which is 4.93 times faster than on Earth.•Through CFD simulations, the hovering stability derivatives on Mars are computed to complete the longitudinal and lateral equations of motion.•Three flight modes including two subsidence modes, and one oscillation mode are identical in the hovering flights on Earth and Mars.•Although the hovering flapping-wing robots are both inherently unstable, the growth of flight disturbances on Mars is slower than on Earth.•Due to the slow growth of the disturbances, the KUBeetle is expected to be able to perform hovering flight on Mars by using the feedback controls. In efforts to search for life-form on a planet other than Earth, many projects have been launched to measure and analyze the surface and atmospheric conditions on Mars. To extend the exploration of Mars, scientists have attempted to perform flight in the extremely thin air environment of Mars. Inspired by the successful controlled flight of NASA's Helicopter on Mars, in this work, we investigate the six-degrees-of-freedom hovering flight dynamics of an insect-like flapping-wing robot, called KUBeetle. To hover the KUBeetle on Mars, using the scaling ratios of air density and gravity on Earth and Mars, we have found that the flapping frequency should be about 113.48 Hz, which is 4.93 times faster than that on Earth, and the required lift on Mars is about 38% of that on Earth. The computational fluid dynamics (CFD) analysis suggests that the lift produced by the flapping wings at the frequency on Mars is close to that predicted by the scaling ratios. A series of simulations are used to compute the stability derivatives to complete the equations of motion. The eigenvalue and eigenvector analyses have identified one fast subsidence mode, one slow subsidence mode, and one divergence oscillation mode in the longitudinal and lateral motions on Mars, which are identical to those on Earth. The dynamic responses of the robot under three initial disturbances in the translational speeds indicate that due to the 94% smaller real part of the complex roots in the divergence oscillation modes of the longitudinal and lateral motions on Mars, the growth of flight disturbances is much slower than on Earth. Therefore, the KUBeetle is capable of hovering flight on Mars, since it has enough time to use the feedback controls to stabilize the system. This work can be used to support the studies of the flight control of flapping wing robots in the Martian atmospheric condition, and to generalize such flight control for other non-terrestrial applications in the atmospheres of other planets and/or their moons.