  We consider the problem of the control of transport in higher dimensional
periodic structures by applied ac fields. In a generic crystal, transverse
degrees of freedom are coupled, and this makes the control of motion difficult
to implement. We show, both with simulations and with an analytical functional
expansion on the driving amplitudes, that the use of quasiperiodic driving
significantly suppresses the coupling between transverse degrees of freedom.
This allows a precise control of the transport, and does not require a detailed
knowledge of the crystal geometry.
