Mobility on planetary surfaces: may walking machines be a viable alternative?

Walking machines are seldom considered as planetary robotic rovers, due to a number of problems linked with their complexity and reliability. Such problems are not intrinsic to walking machines in general, both mainly due to the attempt of building high performance walkers based on layouts derived from nature. As the high design performances are usually not reached, the use of much simpler, non-zoomorphic, layouts is suggested. The aim of the present paper is to describe simplified configurations of legged automatic rovers which match the advantages in reliability of wheeled vehicles with the flexibility in moving on unstructured surfaces intrinsic in walking devices. WALKIE 6, demonstrator of a rigid frames walking microrover developed by the authors, is presented as an example of vehicle for planetary exploration. Other slightly more complex layouts, presently considered for machines with improved performances, are also described.