Strain gauge sensor system and method

A strain gauge sensor system for measuring the strain in a member, said system comprising

• a position sensor device for magnetically measuring the position of a moving magnet;
• a trigger sensor device for triggering said position sensor device in response to magnetically sensing an adjacent moving magnet;
• a sensor target assembly comprising a plurality of magnets carried spaced apart by individual gauge lengths along said member, wherein said position and trigger sensor devices are configured spaced apart along side a desired path of travel of said member such that, when said member is fed along said desired path of travel, said trigger sensor device, in response to sensing a passing magnet of said sensor target assembly, triggers said position sensor device to measure the position of an adjacent passing magnet, wherein said desired path of travel is substantially linear or non-linear and said position sensor device comprises an array of magnetoresistive sensors or Hall Effect sensors spaced from said assembly by an airgap distance, wherein said trigger sensor device comprises at least one analog or digital magnetoresistive or a Hall Effect sensor and optionally a comparator coupled to said position sensor device for generating a trigger signal;
• a controller coupled to the output of said trigger sensor and said array of magnetoresistive or Hall Effect sensors such that said controller, in response to receiving said trigger signal, reads the outputs of said array of magnetoresistive or Hall Effect sensors and compares the measured gauge length determined from said outputs with a predetermined original gauge length to thereby provide the strain in said gauge length;
• a plurality of RFID tags for identifying individual gauge lengths being measured by said strain gauge sensor system, said RFID tans being carried on said member between respective magnets;
• and
• a RFID reader located along side said desired path of travel for reading each RFID tag successively passing said RFID reader, said RFID reader being coupled to said controller to enable said controller to associate said RFID tag with said strain in said gauge length identified by said RFID tag.

A method of measuring strain in a member, said method comprising carrying a plurality of magnets spaced apart by gauge lengths along a length of said member;

• providing a position sensor device spaced apart from a trigger sensor device,
• straining said member;
• moving said member under strain past said position sensor and trigger sensor devices;
• generating a trigger signal in response to sensing the magnetic field of a passing magnet using said trigger sensor;
• transmitting said trigger signal to said position sensor device;
• sensing the magnetic field of an adjacent passing magnet using said position sensor device,
• generating a position signal using said position sensor device in response to receiving said trigger signal,
• determining the strain in said gauge length between said adjacent magnets from said position signal;
• carrying RFID tags on said member between said magnets;
• and reading said RFID tans to identify each gauge length.