A theoretical model of avian flight is developed which simulates wing motion through a class of methods known as predictive simulation. This approach uses numerical optimization to predict power-optimal kinematics of avian wings in hover, cruise, climb and descent. The wing dynamics capture both aerodynamic and inertial loads. The model is used to simulate the flight of the pigeon, Columba livia, and the results are compared with previous experimental measurements. In cruise, the model unearths a vast range of kinematic modes that are capable of generating the required forces for flight. The most efficient mode uses a near-vertical stroke-plane and a flexed-wing upstroke, similar to kinematics recorded experimentally. In hover, the model predicts that the power-optimal mode uses an extended-wing upstroke, similar to hummingbirds. In flexing their wings, pigeons are predicted to consume 20% more power than if they kept their wings full extended, implying that the typical kinematics used by pigeons in hover are suboptimal. Predictions of climbing flight suggest that the most energy-efficient way to reach a given altitude is to climb as steeply as possible, subjected to the availability of power.
Piezoelectric bending actuators utilise the inverse piezoelectric effect to convert input electric energy to useful mechanical work. A comprehensive analytical model of the dynamic electromechanical behaviour of a unimorph piezoelectric actuator has been developed and successfully validated against experimental data. The model provides a mapping between force, displacement, voltage and charge. Damping is modelled using experimental data. Experimental validation is based on measurement of mode shape and frequency response of a series of unimorph beams of varying length but of the same thickness and material. The experimental frequency response is weakly nonlinear with excitation voltage, with a reduction in natural frequency and increase in damping with increasing excitation amplitude. An expression for the electromechanical coupling factor has been extracted from the analytical model and is used as the objective for parametric design studies. The design parameters are thickness and Young’s modulus ratios of the elastic and piezoceramic layers, and the piezoelectric constant k31. The operational design point is defined by the damping ratio. It is found that the relative variation in the electromechanical coupling factor with the design parameters for dynamic operation is similar to static operation; however, for light damping, the magnitude of the peak electromechanical coupling factor will typically be an order of magnitude greater than that of static operation. For the actuator configuration considered in this study, it is shown that the absolute variation in electromechanical coupling factor with thickness ratio for dynamic operation is same as that for static operation when the damping ratio is 0.44.
Flight is a key feature in the evolution of birds. Wing anatomy reflects many aspects of avian biology such as flight ability. However, our knowledge of the flight musculature has many gaps still, particularly for the distal wing. Therefore, the aim of this work was to investigate the form–function relationship of the forelimb myology of birds to understand the role of individual muscles during flight. Dissections of six species of birds of prey were performed to collect numerical data of muscle architecture, which is the primary determinant of muscle function and force‐generation capacity. Birds of prey are a highly diverse group that presents different flight styles throughout the taxa, making them a good model for our purposes. Wing muscle mass (MM) isometrically scaled with body mass1.035, muscle length to MM0.343, and fascicle length (FL) scaled allometrically to MM0.285. The shoulder musculature scaled differently than the other regions where the FL increases more slowly than would be expected in geometrically similar animals, which affects flight mechanics. A proximal‐to‐distal reduction of MM occurs, which helps to minimize the wing moment of inertia during flight while allowing precise control of the distal wing. Interestingly, the distribution of MM appeared to be species‐specific, suggesting a functional signal. This study provides numerical information of muscle architecture of the avian wing that helps us to understand muscle function and its implication in flight, and can be used in future studies of flight mechanics. Anat Rec, 302:1808–1823, 2019. © 2019 American Association for Anatomy
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.