The projected pattern correlation technique for vibration measurements

Konrath, Robert; Klinge, Falk; Schroeder, A. C.; Kompenhans, Jürgen; Fuellekrug, U.

doi:10.1117/12.579572

Cited by 7 publications

(2 citation statements)

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“…The technique is a combination of stereophotogrammetry and correlation algorithms (Raffel et al 1998) together with a projected pattern (Konrath et al 2004). …”

Section: Measurement Techniquementioning

confidence: 99%

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Avian wing geometry and kinematics of a free-flying barn owl in flapping flight

Wolf

Konrath

2015

Exp Fluids

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to produce thrust and lift in an efficient way in this Reynolds number regime. The flapping motions carried out by birds follow very complex movements of the wing and body which can only be characterized by a set of parameters. Besides the four main motion components (pitch, plunge, in and out fold and sweep), which can vary in amplitude, motion form, frequency and velocity, the phase relations between these components are also important for the aerodynamic performance. Furthermore, the wings of birds are highly flexible and adaptive, which means that wing parameters as the incidence angle, camber, thickness distributions are changing during flapping motion as well. Recent studies show the influence of single parameters on the aerodynamic performance of a flapping wing (e.g. phase angle between pitch and plunge, wing flexibility, Reynolds number Send 1996; Anderson et al. 1998, wing flexibility Heathcote andGursul 2007; Reynolds number Ol et al. 2009). However, due to the amount of parameters which can be modulated, the insight remains selective. Therefore, assuming that natural flyers use highly efficient flight mechanisms, their movement parameters can be used as a base for further investigations on flapping motions for technical applications (Platzer et al. 2008).Revealing the mysteries of nature is, however, often a challenging task, since living animals restrict the application of measurement techniques. Therefore, the history of bird flight examination is close related to the development of nonintrusive measurement techniques. One of the first quantitative measurements of birds in flight was performed by Bilo (1971). He applied the measurement technique stereophotogrammetry to sparrows in a wind tunnel. However, he used manually determined correspondences of distinct points on the bird, and therefore, the resolution (≈120 points, only on the upper side) and the accuracy were limited. Nevertheless, stereophotogrammetry is still in use for Abstract This paper presents results of high-resolution three-dimensional wing shape measurements performed on free-flying barn owls in flapping flight. The applied measurement technique is introduced together with a moving camera set-up, allowing for an investigation of the free flapping flight of birds with high spatial and temporal resolution. Based on the three-dimensional surface data, a methodology for parameterizing the wing profile along with wing kinematics during flapping flight has been developed. This allowed a description of the spanwise varying kinematics and aerodynamic parameters (e.g. effective angles of attack, camber, thickness) of the wing in dependence on the flapping phase. The results are discussed in detail using the data of a single flight, whereas a comparison of some kinematic parameters obtained from different flights is given too.

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“…The technique is a combination of stereophotogrammetry and correlation algorithms (Raffel et al 1998) together with a projected pattern (Konrath et al 2004). …”

Section: Measurement Techniquementioning

confidence: 99%

“…In this study, the projected pattern correlation technique (Konrath et al 2004) is modified to perform high-resolution-i.e. surfaces created by more than 20,000 measurement points-timeresolved (1 kHz) measurements of feathered surfaces of free-flying birds with high accuracy.…”

Section: Introductionmentioning

confidence: 99%