Biomedical Engineering Reference
In-Depth Information
KINEMATICS
3.0 HISTORICAL DEVELOPMENT AND COMPLEXITY
OF PROBLEM
Interest in the actual patterns of movement of humans and animals goes back
to prehistoric times and was depicted in cave drawings, statues, and paint-
ings. Such replications were subjective impressions of the artist. It was not
until a century ago that the first motion picture cameras recorded locomotion
patterns of both humans and animals. Marey, the French physiologist, used
a photographic “gun” in 1885 to record displacements in human gait and
chronophotographic equipment to get a stick diagram of a runner. About the
same time, Muybridge in the United States triggered 24 cameras sequentially
to record the patterns of a running man. Progress has been rapid during this
century, and we now can record and analyze everything from the gait of a
child with cerebral palsy to the performance of an elite athlete.
The term used for these descriptions of human movement is kinematics.
Kinematics is not concerned with the forces, either internal or external, that
cause the movement but rather with the details of the movement itself. A com-
plete and accurate quantitative description of the simplest movement requires
a huge volume of data and a large number of calculations, resulting in an
enormous number of graphic plots. For example, to describe the movement
of the lower limb in the sagittal plane during one stride can require up to
50 variables. These include linear and angular displacements, velocities, and
accelerations. It should be understood that any given analysis may use only a
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