Rectangular pinning arrays of Ni dots define a potential landscape for vortex motion in Nb films. Magnetotransport experiments in which two in-plane orthogonal electrical currents are injected simultaneously allow one to select the direction and magnitude of the Lorentz force on the vortex lattice, thus providing the angular dependence of the vortex motion. The background dissipation depends on the angle at low magnetic fields, which is progressively smeared out with increasing field. The periodic potential locks in the vortex motion along channeling directions. Because of this, the vortex-lattice direction of motion is up to ${85}^{\mathrm{o}}$ away from the applied Lorentz force direction.