Side-Slipping Locomotion of a Miniature, Reconfigurable Limb/Tread Hybrid Robot

Holonomic behavior is desirable in the tight confines of a rubbled, collapsed-structure environment. But arbitrary motion is difficult to achieve, mechanically, particularly since treads are the most common form of locomotive device in search and rescue robots. We are developing a reconfigurable suite of locomotive modules that permit side-slipping locomotion. Initially designed as add-on modules to the TerminatorBot limbed crawler to create limb/tread hybrid robots, the modules can also be assembled with one another to produce holonomic differential drive robots, as well. This paper describes the design of a transverse tread module with unique buckling grousers that creates a tread/limb hybrid robot capable of both forward locomotion and transverse locomotion. Also described is a two-dimensional tread module that provides motive force in both the longitudinal and transverse directions. Two of these modules together in a differential drive configuration provides true holonomic capability. The addition of articulated linkages between modules provides holonomic serpentine behavior.