A stage assembly for moving and positioning a device is provided herein. The stage assembly includes a stage base, a stage, a stage mover assembly, a reaction mass assembly, a reaction mover assembly, and a control system. The stage mover assembly moves the stage relative to the stage base. The reaction mass assembly reduces the reaction forces created by the stage mover assembly that are transferred to the stage base. The reaction mover assembly adjusts the position of the reaction mass assembly relative to the stage base. Uniquely, the control system controls and directs current to the reaction mover assembly in a way that minimizes the influence of disturbances created by the reaction mover assembly on the stage assembly. More specifically, the timing and/or the amount of current from the control system directed to the reaction mover assembly is varied to minimize the influence of the disturbances created by the reaction mover assembly on the stage assembly. With this design, the reaction mover assembly has less influence upon the position of the stage base. This allows for more accurate positioning of the device by the stage assembly and better performance of the stage assembly.