Patent ID: 8662215

Claim:
A method performed by a robot, the method comprising: assuming a stable ascending position, wherein: the robot comprises: a chassis having a chassis center of gravity; a set of driven flippers, each flipper having a proximal end, a distal end, and a flipper center of gravity therebetween, each the proximal end of each flipper coupled to the chassis near the leading end of the chassis; a neck having a pivot end, a distal end, and a neck center of gravity therebetween, the neck pivotable about a second pivot axis substantially at the leading end of the chassis; and a sensor head at the distal end of the neck, the head having a pivot end, a distal end, and a head center of gravity therebetween, the head pivotable with respect to the neck about a third pivot axis at the distal end of the neck; and in the stable ascending position, the centers of gravity of the head, neck, and flippers are positioned to shift a vertical projection of the overall center of gravity of the robot to at least a first point in front of the rearmost main track ground contact point and at least a second point behind the foremost flipper track ground contact point; and assuming an unstable stair ascending position in which the centers of gravity of the head, neck, and flippers are positioned to shift a vertical projection of the overall center of gravity of the robot to outside the stable range.