Multi-fiber cylinder position sensor using time-of-flight technique
First Claim
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1. A fluid actuated cylindrical actuator is provided comprising:
- a cylinder having first and second end;
an end cap fixed to the first end of the cylinder and having a rod opening;
a piston disposed in the cylinder;
a rod coupled to the piston and extending from inside the cylinder to outside the cylinder and passing through the rod opening;
a first light guide extending from inside the cylinder to outside the cylinder and adapted to transmit at least a first beam of laser light at a first frequency from outside the cylinder to inside the cylinder and to bar the passage of the fluid;
and a plurality of second light guides having first ends extending from inside the cylinder to outside the cylinder and distal second ends that are coupled to at least one light detector, wherein each of the plurality of second light guides is configured to substantially simultaneously transmit at least a first reflected portion of the beam of laser light from inside the cylinder to outside the cylinder.
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Abstract
A hydraulic actuator is disclosed having a cylinder with a piston that is moved by hydraulic fluid. A light guide in one end of the cylinder directs a laser beam into the cylinder, and off the piston where the beam is reflected. The beam then exits the cylinder through at least two light guides connected to two corresponding optical fibers. Each of the optical fibers are joined together into one fiber that carries the reflected beam of light to a photo-diode located remote from the cylinder. A control circuit measures the time of flight of the laser beam.
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Citations
25 Claims
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1. A fluid actuated cylindrical actuator is provided comprising:
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a cylinder having first and second end;
an end cap fixed to the first end of the cylinder and having a rod opening;
a piston disposed in the cylinder;
a rod coupled to the piston and extending from inside the cylinder to outside the cylinder and passing through the rod opening;
a first light guide extending from inside the cylinder to outside the cylinder and adapted to transmit at least a first beam of laser light at a first frequency from outside the cylinder to inside the cylinder and to bar the passage of the fluid;
and a plurality of second light guides having first ends extending from inside the cylinder to outside the cylinder and distal second ends that are coupled to at least one light detector, wherein each of the plurality of second light guides is configured to substantially simultaneously transmit at least a first reflected portion of the beam of laser light from inside the cylinder to outside the cylinder. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A hydraulic actuator for an agricultural or construction vehicle comprising:
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a cylinder having a substantially circular internal diameter and a longitudinal cylindrical axis;
a piston having a substantially circular outer diameter and configured to be received in and hydraulically sealed against the inner diameter of the cylinder;
a piston rod with a substantially circular outer rod diameter that is fixed to the piston and extends from the piston inside the cylinder, through a first end wall of the cylinder to a location outside the cylinder, wherein the first end wall is disposed to enclose and seal a first end of the cylinder and is substantially perpendicular to the longitudinal axis of the cylinder;
a second end wall fixed to the cylinder and disposed to seal a second end of the cylinder substantially perpendicular to the longitudinal axis of the cylinder, the second end wall including a first optical path configured to transmit a beam of laser light through the second end wall to a reflective surface fixed to the piston and further including a plurality of second optical paths returning from the reflective surface to transmit the reflected beam of laser light back through the end wall in a plurality of return paths;
a first optical fiber optically and mechanically coupled to the second end wall to transmit the beam of laser light from a remote laser light source to the first optical path; and
a plurality of second optical fibers optically and mechanically coupled to the second end wall to transmit the reflected beam of laser light to at least one remote laser light receiver. - View Dependent Claims (8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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13. A method of determining the position of a piston in a hydraulic cylinder includes the steps of:
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generating a beam of laser light;
reflecting the beam of laser light off a surface fixed to move axially with the piston;
receiving a first portion of the reflected beam by a first reflected light guide and a second portion of the reflected beam by a second reflected light guide;
conducting the first and second portions of the reflected beam through first and second optical fibers to at least one remotely located light detector; and
calculating a first time of flight of the beam based at least upon the first and second portions of reflected light.
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Specification