A three-legged dog is a pretty sad sight. But researcher Martin Gross of the University of Jena in Germany
thinks he can learn something about locomotion from them, which could be useful for robots.
He noticed that his brother's three-legged dog, despite missing a hind limb due to cancer, was still faster than three other family dogs who had all four legs.
The same cannot be said of robots. If they lose a limb, they're likely to topple over, since they cannot readjust to the new way of walking. The entire robot could be rendered useless.
In a press release, Gross said robots are not meant to operate on an odd number of legs, regardless of what The Jetsons thinks. "Natural terrestrial locomotion is designed for an even number of limbs. After limb loss (e.g. by an injury) a reorganization of the locomotive system is required," he explained.
This study is part of the European Union's Locomorph project to improve robot efficiency and usability, the latest in a string of interesting research projects the EU has commissioned. This project is meant to help develop robots that can adapt in the event of an "injury."
The researchers placed reflective markers on the dogs and then had them run on treadmills for two minutes. Ten high-speed infrared cameras recorded the action, and a computer mapped the trajectory of each of the reflective patches. Gross and his colleagues then compared those paths with ones produced by four-legged dogs running on the treadmill.
They found that the locomotion of a dog's front legs don't seem to change much if it has lost a hind leg. But dogs that have lost a front limb had to compensate more for motion. A dog carries much of its body weight on its front limbs and those legs are also used for braking, so more compensation is needed. Back legs are used more for propulsion.
Next, the team will look at voluntary and involuntary changes to body movement in a variety of animals, including humans.
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