1. A robotic foot comprising: one or more shear sensors configured to measure a shear force against a bottom of the robotic foot; a plurality of displacement measuring cells configured to support the robotic foot and measure a contour of a surface in contact with the bottom of the robotic foot; a plurality of force sensors, each force sensor in series with a corresponding displacement measuring cell of the plurality of displacement measuring cells; and a processor configured to: receive measurements from the one or more shear sensors, and calculate a coefficient of friction between the robotic foot and a surface in contact with the bottom of the robotic foot.