Topic
Inertia
About: Inertia is a research topic. Over the lifetime, 12006 publications have been published within this topic receiving 164291 citations.
Papers published on a yearly basis
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TL;DR: A modified quasi-steady model is developed that can account for the varying magnitudes of the lift and drag coefficients and may also resolve discrepancies in past measurements of wing performance based on translational and revolving motion.
Abstract: Recent studies have demonstrated that a quasi-steady
model closely matches the instantaneous force produced
by an insect wing during hovering flight. It is not clear,
however, if such methods extend to forward flight. In this
study we use a dynamically scaled robotic model of the
fruit fly Drosophila melanogaster to investigate the forces
produced by a wing revolving at constant angular velocity
while simultaneously translating at velocities appropriate
for forward flight. Because the forward and angular
velocities were constant wing inertia was negligible, and
the measured forces can be attributed to fluid dynamic
phenomena. The combined forward and revolving motions
of the wing produce a time-dependent free-stream velocity
profile, which suggests that added mass forces make a
contribution to the measured forces. We find that the
forces due added mass make a small, but measurable,
component of the total force and are in excellent
agreement with theoretical values. Lift and drag
coefficients are calculated from the force traces after
subtracting the contributions due to added mass. The lift
and drag coefficients, for fixed angle of attack, are not
constant for non-zero advance ratios, but rather vary
in magnitude throughout the stroke. This observation
implies that modifications of the quasi-steady model are
required in order to predict accurately the instantaneous
forces produced during forward flight. We show that the
dependence of the lift and drag coefficients upon advance
ratio and stroke position can be characterized effectively
in terms of the tip velocity ratio – the ratio of the
chordwise components of flow velocity at the wing tip due
to translation and revolution. On this basis we develop a
modified quasi-steady model that can account for the
varying magnitudes of the lift and drag coefficients.
Our model may also resolve discrepancies in past
measurements of wing performance based on translational
and revolving motion.
166 citations
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TL;DR: In this article, a detailed study of the transient nonlinear dynamics of an electrically actuated micron scale beam is presented, and a model developed using the Galerkin procedure with normal modes as a basis accounts for the distributed nonlinear electrostatic forces, nonlinear squeezed film damping, and rotational inertia of a mass carried by the beam.
Abstract: A detailed study of the transient nonlinear dynamics of an electrically actuated micron scale beam is presented. A model developed using the Galerkin procedure with normal modes as a basis accounts for the distributed nonlinear electrostatic forces, nonlinear squeezed film damping, and rotational inertia of a mass carried by the beam. Special attention is paid to the dynamics of the beam near instability points. Results generated by the model and confirmed experimentally show that nonlinear damping leads to shrinkage of the spatial region where stable motion is realizable. The voltage that causes dynamic instability, in turn, approaches the static pull-in value.
165 citations
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TL;DR: In this article, a dynamic model of the drillstring including both drillpipe and drillcollars is formulated, which accounts for the gyroscopic effect, the torsional/bending inertia coupling, and the effect of the gravitational force field.
164 citations
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164 citations
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06 Jul 2004
TL;DR: It is shown that the closed loop system can be seen as a feedback interconnection of passive systems, and a proof of asymptotic stability is presented.
Abstract: In this paper a novel approach to the Cartesian impedance control problem for robots with flexible joints is presented. The proposed controller structure is based on simple physical considerations, which are motivating the extension of classical position feedback by an additional feedback of the joint torques. The torque feedback action can be interpreted as a scaling of the apparent motor inertia. Furthermore the problem of gravity compensation is addressed. Finally, it is shown that the closed loop system can be seen as a feedback interconnection of passive systems. Based on this passivity property a proof of asymptotic stability is presented.
163 citations