The uncertain surrounding environment in which smart structures are employed means that a fixed reference base with which to operate sensing/actuation devices cannot be assumed. The distributed placement of piezoceramic devices has made them the most popular choice for such an application. The limited available output force makes it essential to consider the problems of control signal saturation on the robustness of resulting controllers. Much previous work has considered smart structural control in a single dimension. The current work looks at the vibration control of a two-dimensional smart structure. Actuation is applied by means of two pairs of piezoactuators capable of applying moments with a controllable phase and amplitude difference allowing a controllable ratio of bending and torsion motion. The design process of a multivariable (multi-input multi-output) generalized minimum variance control system is discussed. Application to an experimental double cantilever beam system is shown to result in robust closed-loop control. Comparisons to the benchmark of multi-loop control demonstrate numerous advantages of the multivariable system. Results are further supported with the use of sensitivity functions showing the response of the closed-loop systems to frequencies of interest, particularly the important vibrational modes.