Linear position sensing employing two geartooth sensors, a helical gear and a spur gear

Methods and systems for detecting the linear movement of a shaft utilizing at least two geartooth sensors and two gears, one helical gear and one a normal spur gear are disclosed. As the shaft and gears translate in a linear direction, they are also rotating. Due to the fact one gear is a helical gear and the other is not, as the shaft translates mechanically, there will be a change in the phase between the output of a first geartooth sensor with respect to the second geartooth sensor. This change in phase is converted into linear travel using a simple calculation to detect the linear translation of the shaft.