Towards non-hexapod mechanisms for high performance parallel machines

The so-called "hexapods" are extremely popular in the research community, but much less successful in practical industrial uses so far. The paper discusses some reasons that could explain this difference. Alternate solutions, based either on simpler mechanisms or on hybrid mechanisms, are described or recalled. An emphasis is made on some new hybrid mechanisms whose important features are motors rigidly fixed on the base and legs with constant length.