Non-contact magnetostrictive stress sensor with gap compensation field

A sensor system, comprising:

• a sensor assembly for sensing stress in a target, the sensor assembly including a housing, the housing including
• a proximal end and a distal end,
• a first support including a first arm oriented with respect to a central axis extending through the first support,
• a second support including a second arm,
• a first subsystem configured to generate a raw stress signal, and
• a second subsystem having a capacitive proximity sensor element, the second subsystem being configured to generate a raw proximity signal and including a capacitive proximity sensor element laminated within an end portion of the distal portion of the housing, wherein the distal portion of the housing includes an access point configured to provide access the capacitive proximity sensor element from inside the housing;
• a drive system configured to deliver an input stress drive signal to the first subsystem, the drive system including a drive element located on the first arm of the first support and at least one detection element coupled to the second arm of the second support;
• and
• a proximity system configured to deliver an input proximity drive signal to the second subsystem, and generate a reference signal that corresponds to the input proximity drive signal.

A method of sensing stress in a target, comprising:

• delivering a input stress drive signal to a drive element of a sensor assembly including a housing including a distal portion and a proximal portion, thereby inducing a magnetic flux that travels through a target;
• detecting the magnetic flux;
• generating a raw stress signal based on the detected magnetic flux;
• delivering an initial proximity signal to a proximity circuit;
• delivering a reference signal to a gap processor, the reference signal corresponding to the initial proximity signal;
• delivering an input proximity drive signal to a capacitive proximity sensor element laminated within an end portion of the distal end of the housing, the input proximity drive signal delivered by coupling a proximity subsystem configured within the distal end of the housing to the capacitive proximity sensor via an access point configured within the distal portion of the housing, wherein the proximity subsystem is configured to generate the input proximity drive signal delivered to the capacitive proximity sensor;
• generating a raw proximity signal based on a size of a gap between the capacitive proximity sensor element and the target;
• calculating a gap signal from the reference signal and the raw proximity signal, the gap signal corresponding to a voltage of the capacitive proximity sensor element;
• and
• calculating a corrected stress signal from the raw stress signal and the gap signal.

A sensor assembly, comprising:

• a housing including
• a proximal end and a distal end;
• a first support including a first arm oriented with respect to a central axis extending through the first support;
• a second support including a second arm;
• a drive element located on the first arm of the first support and configured to induce a first magnetic flux that travels through a first gap distance between a distal end of the first arm and a surface of a target, and through the target;
• at least one detection element coupled to the second arm of the second support and configured to detect the first magnetic flux;
• and
• a capacitive proximity sensor element located at a fixed position relative to the distal end of the first arm and configured to generate an electric field with a surface of the target, and to generate a raw proximity signal based on a second gap between a distal surface of the capacitive proximity sensor element and the surface of the target, the capacitive proximity sensor element adhered to an exterior surface of the distal end of the housing via an adhesive third support having first and second adhesive surfaces and extending across a portion of the exterior surface of the distal end of the housing, wherein the capacitive proximity sensor element is adhered to the first adhesive surface and the second adhesive surface is adhered to the exterior surface of the distal end of the housing.