US Patent 7980305 Ram BOP position sensor

A method to determine movement of a wellhead component includes sensing a relative position of the wellhead component with a magnetostrictive sensor over a selected interval of time. The method includes sending a signal from the magnetostrictive sensor to a data acquisition device and recording the relative position of the wellhead component with the data acquisition device with respect to the selected interval of time. Further, the method includes comparing the recorded position of the wellhead component with operations data to determine if the relative position is desirable.