Patent ID: 8372019

Claim:
A method for sensing force on a robotically controlled medical instrument, the method comprising: introducing a medical probe into a patient, the medical probe having an elongated probe body comprising a central lumen, and a push-pull member extending axially through the central lumen, a distal end of the push-pull member being attached to a distal end portion of the probe body; mechanically displacing a proximal end of the push-pull member back and forth in a cyclical manner without any external force applied to the distal end portion of the probe body; mechanically displacing the proximal end of the push-pull member back and forth in a cyclical manner with external force axially applied between internal body tissue of the patient and the distal end portion of the probe body; and determining the external force applied between the internal body tissue of the patient and the distal end portion of the probe body, wherein the external force applied between the internal body tissue of the patient and the distal end portion of the probe body is determined by obtaining a baseline force measurement when the distal end portion of the probe body is axially dithered back and forth without any external axial force applied to the distal end portion of the probe body, obtaining a total force measurement when the distal end portion of the probe body is dithered back and forth with the external axial force axially applied between the tissue and the distal end portion of the probe body, and subtracting the baseline force measurement from the total force measurement.