Valkyrie and knotted into a ponytail, sometimes bearing drinking horns, have been discovered throughout Scandinavia. These figures are commonly considered to represent valkyries or dísir. According to Mindy MacLeod and Bernard Mees, the amulets appear in Viking Age graves, and were presumably placed there because "they were thought to have protective powers". The Tjängvide image stone from the Baltic island of Gotland, Sweden features a rider on an eight-legged horse, which may be Odin's eight-legged horse Sleipnir, being greeted by a female, which may be a valkyrie at Valhalla. The 11th century runestone U 1163 features a carving of a female
Legged robot tripod. Four-legged robots also benefit from a lower center of gravity than two-legged systems. Four legged robots include: Six-legged robots, or "hexapods", are motivated by a desire for even greater stability than bipedal or quadrupedal robots. Their final designs often mimic the mechanics of insects, and their gaits may be categorized similarly. These include: Six-legged robots include: Eight-legged legged robots are inspired by spiders and other arachnids, as well as some underwater walkers. They offer by far the greatest stability, which enabled some early successes with legged robots. Eight-legged robots include: Some robots use a combination of legs and wheels.