What does a three legged dog have to do with a walking robot? Plenty, says Discovery news. Both need to learn to walk all over again.
See, a dog knows how to walk with four legs, in a variety of gaits. If the dog then loses one leg (say, to an accident, injury, or whatever), the regular style of walking or running doesn't work anymore, but they can learn to limp in short order. Apparently, this encouraged a German scientist to see if this can be applied to robots, who also need to learn to walk from scratch.
Apparently, every animal on earth has an even number of legs, arranged in pairs, and roboticists have been trying to shoehorn their patterns into robots that have odd numbers of legs, and this works out rather poorly, balance wise. A pattern for an odd number of limbs would be completely different.