Apparatus and method for detecting metal disturbanceduring a medical procedure includes a probe having aninsertion tube, a joint and a joint sensor, containedwithin the probe, for sensing a position of the insertiontube. The joint sensor has first and second subassembliesthat are magnetic transducers. A processor is used formeasuring force using the joint sensor, and has athreshold field value stored therein. The processorcompares a sensed field value to the threshold fieldvalue and identifies a presence metal when the sensedfield value is greater than the threshold field value.
