Abstract: A plural orthogonal feed forward control system with an actuator system for installation on an upper floor or area of a building as an integral part of a building's structural supports to control seismic, wind, or wave disturbances to the structure or building. Control means include upstream and dual orthogonal downstream sensor arrays for determination of input and output error signals, plural orthogonal anti-feedback filters, and the plural adaptive weight updates to best determine the orthogonal components of the cancellation signal. The cancellation signal is acted on by the variable controlling force apparatus consisting of hydraulic or other actuators with stiff rods attached to the building structure and connected with a movable mass. The device works on orthogonal components of the disturbance, and is capable of attenuating simultaneously signals whose spectra contain multiple narrowband and/or combined narrowband and broadband character.