US Patent 11280187 Estimating a formation index using pad measurements

A method for drilling a wellbore through a subterranean formation includes rotating a drill string in the subterranean wellbore to drill. The drill string includes a rotary steerable tool or a steerable drill bit including a plurality of pads configured to extend radially outward from a tool body and engage a wall of the wellbore. Radial displacements of at least one of the pads are measured while rotating (e.g., drilling). A formation index is computed while drilling by processing the measured radial displacements, where the formation index is indicative of a strength or hardness of the subterranean formation.