System and method for detection of metal disturbance based on mutual inductance measurement

Apparatus and method for detecting metal disturbance during a medical procedure includes a probe having an insertion tube, a joint, and a joint sensor for sensing a position of the insertion tube. The joint sensor comprises first and second subassemblies having coils. A processor is used for measuring force using the joint sensor, and having a pre-established baseline value stored therein. The processor detects changes in a position of the insertion tube by applying current to one coil and measures a signal output by a remainder of the other coils. The signal output by a remainder of the coils defines a pickup value, wherein the processor compares the pickup value to the pre-established baseline value and identifies presence of metal when the pickup value is outside of a range of the pre-established baseline value.