That’s what the system of Figure 3 does. It is an X-Y motion arrangement consisting of two pairs of linear drive and bearing systems. Two ball screws drive in the X direction at opposite sides of the framework; two, likewise in the Y direction. For each ball-screw drive, an ac servomotor powered by a vector-control adjustable- frequency drive runs a geared speed reducer with output shaft attached to its ball screw. A universal joint connects the underside of the damper mass to the X-Y system. The mass connects to the power-transmission system but does not ride on it; the effect is to minimize system size and frictional resistance.