Patent ID: 7188993

Claim:
An apparatus comprising: a base assembly comprising a plurality of base legs with each adjacent pair of legs being connected by at least one leg connector assembly, each of said base legs having a bottom resilient member support and a top resilient member support attached thereto; a driver assembly, said driver assembly being movable in a first linear direction and in an opposite linear direction and said driver assembly comprising a plurality of resilient member shafts having ends, each of which resilient member shafts has a driver to payload resilient member attached to each end thereof; a plurality of motor assemblies comprising a motor having a motor shaft to which an eccentric mass is attached, each of said eccentric masses having a centroid, each of said motor assemblies being rigidly connected to said driver assembly and being adapted to rotate the centroid of its eccentric mass in a plane that is parallel to another plane in which said first direction and said opposite direction lie; a payload assembly, said payload assembly being movable in the same directions as said driver assembly and being movably connected to said driver assembly by the driver to payload resilient members and being movably connected to the bottom resilient member support and the top resilient member support of said base assembly by a plurality of payload to base resilient members; and a plurality of reaction mass assemblies, each reaction mass assembly being movable in the same directions as said driver assembly and being movably connected to said payload assembly by a plurality of reaction mass to payload resilient members and movably connected to said base assembly by a plurality of reaction mass to base resilient members; wherein each of said eccentric masses has substantially the same weight and inertial properties, and wherein the eccentric masses are rotatable at substantially the same rotational speed in opposite rotational directions and around axes that lie in the same plane and, during rotation, are operative to produce a first force on said driver assembly in said first direction and a second force on said driver assembly in said opposite direction and substantially no other forces on said driver assembly.