Methods to actively modify the dynamic response of cm-scale FWMAV designs

Abstract

Abstract. Lightweight vibrating structures (such as Flapping Wing Micro Air Vehicle (FWMAV) designs) often require some form of control. To achieve controllability, local structural property changes (e.g., damping and stiffness changes) might be induced in an active manner. The stroke-averaged lift force production of a FWMAV wing can be modified by changing the structural properties of that wing at carefully selected places (e.g., changing the properties of the elastic hinge at the wing root as studied in this work). To actively change the structural properties, we investigate three different methods which are based on: 1) piezoelectric polymers, 2) electrorheological fluids, and 3) electrostatic softening. This work aims to gain simple yet insightful ways to determine the potential of these methods without focusing on the precise modeling. Analytical models of FWMAV wing designs that include control approaches based on these three methods are used to calculate the achievable lift force modifications after activating these methods. The lift force production as a result of a wing flapping motion is determined using a quasi-steady aerodynamic model. Both piezoelectric polymers and electrostatic softening are found to be promising in changing the structural properties and, hence, the lift force production of FWMAV wings. For the control of lightweight FWMAV designs, numerical simulations reveal a promising roll maneuverability due to the induced lift force difference between a pair of opposite wings. Although applied to a specific FWMAV design, this work is relevant for control of small, lightweight, possible compliant, vibrating structures in general.

A Review of Research on the Mechanical Design of Hoverable Flapping Wing Micro-Air Vehicles

“…Therefore, an intelligent actuator-driving mechanism has become a research direction regarding to the flapping mechanism. At present, intelligent actuatordriving mechanisms mainly include piezoelectric actuators [7,[67][68][69][70], electromagnetic actuators [71][72][73][74][75], dielectric elastomer actuators [76,77], and electrostatic actuators [78,79]. Research results have also focused on piezoelectric actuators and electromagnetic actuators.…”

“…Roll et al from Purdue University proposed an insectinspired FWMAV with a weight of 2.6 g and a flapping frequency of over 70 Hz [73,[91][92][93]. This driving system of the aircraft consists of a single electromagnetic coil, a permanent magnet rotor and a "virtual spring" magnet pair.…”