Method and apparatus for reducing countermass stroke with initial velocity

摘要

A countermass stroke reduction assembly is provided. The assembly generally includes a base supporting one or more stages and first and second countermasses. Alternatively, first and second countermasses could be mounted separately from the base. The first and second stages move in one or more degrees of freedom. The countermasses move in at least one degree of freedom. In order to minimize the stroke of the countermasses, a drift velocity and y-intercept are determined off-line from an average position line for the countermass. An initial velocity equal in magnitude but opposite in sense to the drift velocity is then imparted to the countermass at the start of operation. Alternatively or additionally, an initial position offset equal and opposite to the y-intercept may be provided at the start of operation.