CR TidBit – Allometry & Locomotion

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Allometry is the study of the relationship of body size to shape, anatomy, physiology and finally behavior.Allometry is a well-known study, particularly in statistical shape analysis for its theoretical developments, as well as in biology for practical applications to the differential growth rates of the parts of a living organism’s body.

Allometry can be used to study the evolution of size and shape, locomotion of animals etc.

Allometry has been used to study patterns in locomotive principles across a broad range of species. Allometric trends observed in extant animals have even been combined with evolutionary algorithms to form realistic hypotheses concerning the locomotive patterns of extinct species.Allometric study of locomotion involves the analysis of the relative sizes, masses, and limb structures of similarly shaped animals and how these features affect their movements at different speeds .

The following are the principles of Legged locomotion explained through Allometry:

(1).It has been observed that animals of different sizes and masses traveling with the same Froude number(a dimensionless number) consistently exhibit similar gait patterns.

(2)The dynamic similarity hypothesis which states that “animals of different sizes tend to move in dynamically similar fashion whenever the ratio of their speed allows it”.

(3)Body mass has even more of an effect than speed on limb dynamics.

(4)A formula generated through Allometric scaling “Leg stiffness =Peak force/Displacement”.proportional to , where  is body mass.

It has also been found that living organisms of all shapes and sizes utilize spring mechanisms in their locomotive systems, probably in order to minimize the energy cost of locomotion. The allometric study of these systems has fostered a better understanding of why spring mechanisms are so common, how limb compliance varies with body size and speed, and how these mechanisms affect general limb kinematics and dynamics. Thus, Allometry has an importance of studying animal locomotion and can also give some insight of how extinct animals would have walked the earth.


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