This application seems to be one where an Exlar actuator (http://www.exlar.com/) would work well. They have incremental encoders built in which would provide excellent resolution.

Jim Miller
Applications Engineer
Quantum Devices Inc.
www.quantumdev.com
(608) 924-3000

 

Check out a company by the name of Pollak (located in Canton, MA) they are a division of Stoneridge, Inc. They make Cylinder Position Sensors that can be modified to any length and are a sleek design that fits tightly to the outside of the cylinder (using band clamps). Output signal can be customized to your needs.

 

Pulse tach with a rack gear, I have seen them used for absolute positioning of hoist cylinders