Sensor assembly

A sensor assembly for determining a location of a structure that is translated along a movement axis, the sensor assembly comprising:

• a sensor mount;
• a first sensor coupled to the sensor mount, the first sensor being an eddy current sensor having a first X-axis, a first Y-axis and a first Z-axis that are orthogonal to one another, the first X-axis being disposed parallel to the movement axis, the first sensor comprising a first coil that is wound helically around the first Z-axis;
• a second sensor coupled to the sensor mount, the second sensor being an eddy current sensor having a second X-axis, a second Y-axis, and a second Z-axis that are orthogonal to one another, the second X-axis being parallel to the first X-axis, the second Z-axis being parallel to the first Z-axis, the second sensor comprising a second coil that is wound helically around the second Z-axis;
• a first target that is adapted to be coupled to the structure for movement therewith, the first target being formed of an electrically conductive material and being configured to interact with the first sensor to produce a first sensor signal that has a first magnitude that varies in a first predetermined manner with movement of the first target along the first X-axis;
• a second target that is adapted to be coupled to the structure for movement therewith, the second target being formed of an electrically conductive material and being configured to interact with the second sensor to produce a second sensor signal that has a second magnitude that varies in a second predetermined manner with movement of the second target along the second X-axis;
• and
• a controller receiving the first and second sensor signals and responsively determining the location of the structure along the movement axis;
• wherein the first and second targets are configured such that coordinated movement of the first and second targets in a direction parallel to the first and second Z-axes within predefined limits as the structure is moved along the movement axis has no effect on the location of the structure that is determined by the controller.

A method comprising:

• providing a structure that is movable along a movement axis;
• coupling a sensor assembly to the structure, the sensor assembly comprising first and second eddy current sensors and first and second targets that are mounted to the structure for movement along the movement axis;
• sensing the first target with the first eddy current sensor and responsively generating a first sensor signal;
• sensing the second target with the second eddy current sensor and responsively generating a second sensor signal;
• and
• using the first and second sensor signals to determine a location of the structure along the movable axis in a manner that is insensitive to coordinated movement of the first and second targets in a first direction that is perpendicular to the movement axis.