A medical device, comprising: an insertion tube, having a longitudinal axis and having a distal end adapted for insertion through a body passage into a cavity within a body of a patient; an electrode, which is located on the distal end of the insertion tube and is configured to contact tissue in the cavity; at least one position transducer in the distal end of the insertion tube, wherein the at least one position transducer is configured to measure a bend angle of the distal end of the insertion tube; characterized in that the medical devices comprises: a resilient member, which is contained within the distal end of the insertion tube and is configured, when unconstrained, to cause the distal end to bend away from the longitudinal axis in a curved shape and to straighten toward the longitudinal axis when subjected to a force resulting from pressure exerted by the distal end against the tissue in the cavity; and wherein the resilient member is configured to straighten toward the longitudinal axis when the force applied is an inward radial force and wherein the resilient member is made structurally weak such that, if the radial force exceeds a predetermined threshold, the resilient member buckles thereby preventing excessive pressure being exerted by the distal end. an insertion tube, having a longitudinal axis and having a distal end adapted for insertion through a body passage into a cavity within a body of a patient; an electrode, which is located on the distal end of the insertion tube and is configured to contact tissue in the cavity; at least one position transducer in the distal end of the insertion tube, wherein the at least one position transducer is configured to measure a bend angle of the distal end of the insertion tube; characterized in that the medical devices comprises: a resilient member, which is contained within the distal end of the insertion tube and is configured, when unconstrained, to cause the distal end to bend away from the longitudinal axis in a curved shape and to straighten toward the longitudinal axis when subjected to a force resulting from pressure exerted by the distal end against the tissue in the cavity; and wherein the resilient member is configured to straighten toward the longitudinal axis when the force applied is an inward radial force and wherein the resilient member is made structurally weak such that, if the radial force exceeds a predetermined threshold, the resilient member buckles thereby preventing excessive pressure being exerted by the distal end. a resilient member, which is contained within the distal end of the insertion tube and is configured, when unconstrained, to cause the distal end to bend away from the longitudinal axis in a curved shape and to straighten toward the longitudinal axis when subjected to a force resulting from pressure exerted by the distal end against the tissue in the cavity; and wherein the resilient member is configured to straighten toward the longitudinal axis when the force applied is an inward radial force and wherein the resilient member is made structurally weak such that, if the radial force exceeds a predetermined threshold, the resilient member buckles thereby preventing excessive pressure being exerted by the distal end.