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A fluid-pressure actuated piston/cylinder assembly having a sensor capable of reading at least one indicia marking on a piston rod in order to determine the movement and specific location of the piston rod and cylinder relative to each other. The sensor is housed within a sealing gland that is incor

A fluid-pressure actuated piston/cylinder assembly having a sensor capable of reading at least one indicia marking on a piston rod in order to determine the movement and specific location of the piston rod and cylinder relative to each other. The sensor is housed within a sealing gland that is incorporated into the piston/cylinder assembly and is isolated from the internal fluid pressure and external elements. A method for determining the exact location of one of a piston rod and cylinder, relative to the other, is also set forth.

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1. In a fluid-pressure actuated piston/cylinder assembly including a sensor, capable of reading indicia markings, for sensing the movement of a piston and a cylinder relative to each other, a piston rod, having at least one indicia marking on its surface, attached to said piston, said piston/cylinde

1. In a fluid-pressure actuated piston/cylinder assembly including a sensor, capable of reading indicia markings, for sensing the movement of a piston and a cylinder relative to each other, a piston rod, having at least one indicia marking on its surface, attached to said piston, said piston/cylinder assembly having at least one open end, a sealing gland incorporated into said at least one open end and with said piston rod operatively and sealingly extending axially through a longitudinal through bore in said sealing gland, wherein said improvement comprises:said sensor being housed within said sealing gland for sensing said at least one indicia marking during said movement in order to determine the specific location of the piston rod and cylinder relative each other; andsaid sealing gland including a plurality of seals for isolating said sensor from both a pressurized chamber within said cylinder and from contaminants outside of the piston/cylinder assembly. 2. The piston/cylinder assembly as in claim 1, wherein said sensor is housed within said sealing gland in a radial bore that intersects said longitudinal through bore. 3. The piston/cylinder assembly as in claim 1, wherein said at least one indicia marking is provided on said piston rod by changing the molecular structure of said piston rod surface. 4. The piston/cylinder assembly as in claim 1, wherein said at least one indicia marking is provided on said piston rod by using a Nd-YAG laser. 5. The piston/cylinder assembly as in claim 1, wherein said at least one indicia marking is provided on said piston rod by using a laser impingement process. 6. The piston/cylinder assembly as in claim 1, wherein said at least one indicia marking is provided on said piston rod without altering the geometry of the piston rod surface. 7. The piston/cylinder assembly as in claim 1, wherein said at least one indicia marking includes a mid position stroke marking. 8. The piston/cylinder assembly as in claim 1, further including a plurality of indicia markings. 9. The piston/cylinder assembly as in claim 8, wherein said plurality of indicia markings are in the form of an incremental scale. 10. The piston/cylinder assembly as in claim 8, wherein said indicia markings are in the form of an absolute scale. 11. The piston/cylinder assembly as in claim 8, wherein said indicia markings are in the form of an end of stroke scale. 12. The piston/cylinder assembly as in claim 1, wherein said sensor is located outside of a pressurized chamber within said cylinder. 13. An apparatus for sensing the reciprocal movement of a piston and cylinder, within a fluid pressure-operated actuator, including a piston rod attached to the piston and a seal gland, having a longitudinal through bore, closing an open end of said cylinder, said apparatus comprising:an array of indicia markings formed on said piston rod;said seal gland including a radial bore intersecting said longitudinal through bore; anda fiber optical sensor, capable of reading indicia markings, located within the radial bore of said sealing gland, but isolated from said fluid pressure, for reading said indicia markings on said piston rod, and thereby determining the relative position of one of said piston rod and said cylinder to each other. 14. In an improved linear position sensing system for detecting the reciprocal movement of a piston and cylinder relative to each other including a piston rod attached to said piston, said cylinder having at least one open end, closed by a seal gland having a longitudinal through bore, with said piston rod operatively extending therethrough in a sealed manner, wherein said improvement comprises:a plurality of longitudinally arranged indicia markings provided on said piston rod;said seal gland, including a bore extending radially outward from said longitudinal through bore; anda fiber optical sensor located within said radial bore for reading said indicia markings and thereby detecting the precise position of one of said piston rod and said cylinder relative to each other. 15. The improved linear position sensing system of claim 14 further including means for converting an optical signal to an electronic signal. 16. An improved piston and cylinder assembly for sensing the movement of the piston and the cylinder relative to each other comprising:a plurality of indicia markings on a piston rod attached to said piston, one of said piston and cylinder being movable relative to the other;a photo sensor mounted in a seal gland, said seal gland having a plurality of seals, closing an open end of said cylinder assembly but permitting the sealed movement of said piston rod relative thereto, said photo sensor reading said indicia marking on said piston rod during the movement thereof relative to said seal gland and thereby determining the location of one of said piston rod and said cylinder relative to the other. 17. The improved piston and cylinder assembly of claim 16 wherein said photo sensor is mounted within a radial bore in said seal gland. 18. In an existing fluid pressure piston/cylinder assembly, including a cylinder, a piston with a piston rod and the piston rod operatively extending through a longitudinal through bore of a seal gland that closes the open end of said cylinder, an improved apparatus for sensing the movement of the piston relative to the cylinder, said improvement comprising:the addition of an array of indicia markings on said piston rod; anda fiber optical sensor located within said seal gland for reading said indicia markings and thereby determining the location of the piston rod relative to the cylinder. 19. In a pressure fluid-operated piston/cylinder assembly having a piston and a cylinder movable relative to each other, said assembly further including a piston rod attached to said piston and having a plurality of indicia markings on said piston rod, said cylinder assembly having at least one open end, an apertured seal gland incorporated into said at least one open end permitting sealed movement of said piston rod therethrough, wherein the improvement comprises:the addition of a fiber optical sensor within said seal gland for reading said indicia markings during said movement in order to determine the precise location of the piston rod and cylinder relative to each other. 20. A pressurized actuator, including a piston and cylinder, capable of movement relative to each other, comprising in combination:a. said cylinder having at least one open end and containing a pressurized working fluid;b. said piston slidably contained within said cylinder and reactive to said working fluid;c. a piston rod, attached to said piston, having a plurality of indicia markings on its surface;d. a sealing gland incorporated into said at least one open end of said cylinder, having:a central axial bore for receiving said piston rod;a peripheral surface of said bore located on the outside of said central axial aperture;an outer surface;a radial bore extending from said central axial bore radially outward to said outer surface; andsaid peripheral surface of said bore having a series of spaced circumferential recesses extending outwardly therefrom;e. a sensor housed within said radial bore for reading said indicia markings during movement of said piston and cylinder relative to each other and for determining the specific location of said piston rod and said cylinder relative to each other. 21. The apparatus, as in claim 20, wherein at least one of said series of spaced circumferential recesses is located on each side of said sealing gland radial bore and receives circumferential seals that are in sealing contact with said piston rod. 22. The apparatus, as in claim 20, wherein said sensor is isolated from said working fluid. 23. A method of determining the specific location of one of a piston rod and cylinder relative to the other, in a fluid-pressure operated piston-cylinder assembly, including a sensor capable of reading indicia markings, sa id piston rod being attached to a piston, and a seal gland having a longitudinal through bore, for permitting sealed movement of said piston rod, closing an open end of said assembly, wherein said method comprises:a. providing an array of indicia markings on said piston rod;b. mounting said sensor within said seal gland so as to isolate same from said fluid pressure within said piston-cylinder assembly and from contaminants outside the piston-cylinder assembly; andc. moving one of said piston and cylinder relative to the other. 24. A method for determining the exact location of one of a piston rod and cylinder by monitoring the reciprocal movement of one of said piston rod and cylinder relative to each other, in a fluid pressure operated piston-cylinder assembly, including a sensor capable of reading indicia markings, said piston rod being attached to a piston within said cylinder and a seal gland, having a longitudinal through bore for permitting sealed movement of said piston rod, closing an open end of said assembly and having a plurality of seals, wherein said method comprises the steps of:a. providing on said piston rod, an array of indicia markings in the form of a scale capable of defining a specific location;b. mounting said sensor within a further bore within said seal gland that intersects said through bore;c. reading said scale, via said sensor, during said reciprocal movement; andd. conveying output readings of said sensor to a location observable by an operator. 25. In a fluid-pressure actuated piston/cylinder assembly including a fiber optical sensor, capable of reading indicia markings, for sensing the movement of a piston and a cylinder relative to each other, a piston rod, having at least one indicia marking on its surface, attached to said piston, said piston/cylinder assembly having a least one open end, a sealing gland incorporated into said at least one open end and with said piston rod operatively and sealingly extending axially through a longitudinal through bore in said sealing gland, wherein said improvement comprises:said sensor being housed within said sealing gland for sensing said at least one indicia marking during said movement in order to determine the specific location of the piston rod and cylinder relative each other. 26. An apparatus for sensing the reciprocal movement of a piston and cylinder, within a fluid pressure-operated actuator, including a piston rod attached to the piston and a seal gland, having a longitudinal through bore, closing an open end of said cylinder, said apparatus comprising:an array of indicia markings formed on said piston rod;said seal gland including a radial bore intersecting said longitudinal through bore; anda sensor, capable of reading indicia markings, located within the radial bore of said sealing gland, but isolated from said fluid pressure and from contaminants outside of said apparatus, for reading said indicia markings on said piston rod, and thereby determining the relative position of one of said piston rod and said cylinder to each other.