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Recent work on joint kinematics indicates that the finite centroid (centre of rotation) and the finite helical axis (axis of rotation, screw axis, twist axis) are highly susceptible to measurement errors when they are experimentally determined from landmark position data. This paper presents an analytical model to describe these effects, under isotropic(More)
To date, the diagnosis of whiplash injuries has been very difficult and largely based on subjective, clinical assessment. The work by Winters and Peles Multiple Muscle Systems--Biomechanics and Movement Organization. Springer, New York (1990) suggests that the use of finite helical axes (FHAs) in the neck may provide an objective assessment tool for neck(More)
The present paper describes an algorithm for estimating the translation vector and the rotation matrix of a moving body from noisy measurements on the spatial co-ordinates of at least three non-collinear markers. A sensitivity analysis of the estimated parameters and of the helical axis is presented in terms of characteristics of the marker distribution.(More)
In view of the singularities, asymmetries and other adverse properties of existing, three-dimensional definitions for joint and segment angles, the present paper proposes a new convention for unambiguous and easily interpretable, 3-D joint angles, based on the concept of the attitude 'vector' as derived from Euler's theorem. The suggested standard can be(More)
An analytical stereophotogrammetric method is introduced to measure the three-dimensional geometry of articular surfaces in vitro. Information of this kind is particularly useful for mathematical joint models and anthropological studies. The method requires no specific equipment, such as a stereocomparator, contrarily to other techniques reported (e.g.(More)
Traditional studies of human movement by photographic methods require tedious, error-prone, and expensive data reduction. Various optoelectronic methods have been designed. A commercially available system, SELSPOT, purchased for the Cleveland VAMC Motion Study Laboratory, is described. Sequentially pulsed light-emitting-diode targets on the subject are(More)