Researchers from the Nagoya Institute of Technology, Japan recently published a study where they propose and validate an analytical model for studying cheetah galloping by comparing its predictions with cheetah data.
While improving upon the current understanding of cheetah’s locomotion, their findings pave the way for designing legged robots. The focal point was with seeking to understand what it takes to be the fastest land predator and to use the biological findings in relation to robotics.
With the cheetah being the fastest land animal, exactly how does the big cat achieve this speed? To date, little has been understood about the dynamics underlying its characteristic “flight” and spine movement.
This has now changed with the development of a new analytical model to enable the study of a cheetah galloping. The model has been verified by comparing predictions with cheetah data.
The model has shown how cheetahs deploy a “galloping” gait at their fastest speeds. This uses two different types of “flight”: one with the forelimbs and hind limbs beneath their body following a forelimb liftoff, called “gathered flight.”
The other form of flight occurs with the forelimbs and hind limbs stretched out after a hind limb liftoff, called “extended flight”. Furthermore, cheetahs show appreciable spine movement during flight, alternating between flexing and stretching in gathered and extended modes. This adds to the high-speed locomotion.
Of these special movements, it is extended flight that enables cheetahs to accelerate to high speeds. An important variable is based on ground reaction forces.
These insights enabled the scientists to develop computer modeling in order to gain a better dynamic perspective of the animal gait and spine movement during running. This was a two-dimensional model comprising two rigid bodies and two massless bars (representing the cheetah’s legs), with the bodies connected by a joint to replicate the bending motion of the spine and a torsional spring. Additionally, they assumed an anterior-posterior symmetry, assigning identical dynamical roles to the fore and hind legs.
The researchers were able to verify these criteria with measured cheetah data, revealing that cheetah galloping in the real world indeed satisfied the criterion for two flight types through spine bending.
It is hoped this insight can be applied to the mechanical and control design of legged robots in the future. Legged robots are a type of mobile robot which use articulated limbs, such as leg mechanisms, to provide locomotion.
The research has been published in the journal Scientific Reports, under the title “Dynamical determinants enabling two different types of flight in cheetah gallop to enhance speed through spine movement.”
The Nagoya Institute of Technology (NITech) aims to create a better society by providing global education and conducting cutting-edge research in various fields of science and technology.
