Displacement sensor utilizing ronchi grating interference

Abstract

A load cell to measure displacements transferred by a supported structure to the load cell including an elongated mounting base portion configured to attach to a support structure, a coupling portion operably supporting the support structure, a middle portion disposed above the elongated mounting base portion and below the coupling portion, the middle portion including a hollow interior section with an opening into the hollow interior section, wherein the mounting base portion, the coupling portion and the middle portion comprise a similar material, and a post extending from the elongated mounting base portion and protruding into the hollow interior section of the middle portion.

The invention claimed is: 
     
         1 . A load cell to measure displacements transferred by a supported structure to the load cell, comprising:
 an elongated mounting base portion configured to attach to a support structure;   a coupling portion operably supporting the support structure;   a middle portion disposed above the elongated mounting base portion and below the coupling portion, the middle portion including a hollow interior section with an opening into the hollow interior section, wherein the mounting base portion, the coupling portion and the middle portion comprise a similar material; and   a post extending from the elongated mounting base portion and protruding into the hollow interior section of the middle portion.   
     
     
         2 . The load cell of  claim 1 , wherein the coupling portion includes an aperture with a centerline, and wherein the post is disposed between the centerline and the elongated mounting base portion. 
     
     
         3 . The load cell of  claim 2 , wherein the hollow interior section is disposed between the centerline and the elongated mounting base portion. 
     
     
         4 . The load cell of  claim 3 , wherein the post has a vertical centerline, and wherein the vertical centerline and the centerline of the aperture of the coupling portion intersect at an orthogonal angle. 
     
     
         5 . The load cell of  claim 4 , further comprising:
 a first optical array sensor attached to the post within the hollow interior section.   
     
     
         6 . The load cell of  claim 5 , further comprising:
 a first immobile grating film applied over the first optical array sensor.   
     
     
         7 . The load cell of  claim 6 , further comprising:
 a first light source disposed within the hollow interior section.   
     
     
         8 . The load cell of  claim 7 , further comprising:
 a first mobile grating film interconnected with the middle portion within the hollow interior section, wherein the first light source emits light that transmits through the first mobile grating film, then through the first immobile grating film, and then to the first optical array sensor.   
     
     
         9 . The load cell of  claim 8 , wherein the post further includes a first surface forming a plane parallel with a longitudinal midline of the load cell, wherein the middle portion includes a first surface forming a plane parallel with a longitudinal midline of the load cell, accessible from the hollow interior section, and facing the first surface of the post, wherein the first optical array sensor is affixed to the first surface of the post, wherein the first light source is affixed to the first surface of the middle portion, and wherein the first immobile grating film faces the first mobile grating film. 
     
     
         10 . The load cell of  claim 9 , further comprising:
 a second optical array sensor attached to the post within the hollow interior section; and   a second immobile grating film applied over the second optical array sensor.   
     
     
         11 . The load cell of  claim 10 , further comprising:
 a third optical array sensor attached to the post within the hollow interior section; and   a third immobile grating film applied over the third optical array sensor.   
     
     
         12 . The load cell of  claim 1 , wherein the support structure comprises a fifth wheel, and wherein the coupling portion pivotably supports the fifth wheel. 
     
     
         13 . The load cell of  claim 1 , wherein the mounting base portion, the coupling portion and the middle portion are an integral, single piece. 
     
     
         14 . A load cell to measure displacements transferred by a supported structure to the load cell comprising:
 a mounting base portion configured to attach to a support structure;   a coupling portion operably supporting the supported structure;   a middle portion disposed above the elongated mounting base portion and below the coupling portion;   a first optical array sensor positioned between the mounting base portion and the coupling portion;   a first immobile grating film applied over the first optical array sensor;   a first light source;   a first mobile grating film interconnected with the middle portion, wherein the first light source emits light that transmits through the first mobile grating film, then through the first immobile grating film, and then to the first optical array sensor; and   a second optical array sensor arranged substantially orthogonally with respect to the first optical array.   
     
     
         15 . The load cell of  claim 14 , wherein the first optical array sensor includes an array of photodiodes that are arranged vertically, and wherein, both the first immobile grating film and the first mobile grating film include a grid of lines and at least either the grid of lines of the first immobile grating film or the grid of lines of the first mobile grating film are arranged horizontally. 
     
     
         16 . The load cell of  claim 15 , further comprising:
 a second immobile grating film applied over the second optical array sensor;   a second light source; and   a second mobile grating film interconnected with the middle portion within the hollow interior section, wherein the second light source emits light that transmits through the second mobile grating film, then through the second immobile grating film, and then to the second optical array sensor.   
     
     
         17 . The load cell of  claim 16 , wherein the second optical array sensor includes an array of photodiodes that are arranged laterally, and wherein both the second immobile grating film and the second mobile grating film include a grid of lines and at least either the grid of lines of the second immobile grating film or the grid of lines of the second mobile grating film are arranged vertically. 
     
     
         18 . The load cell of  claim 17 , further comprising:
 a third optical array sensor positioned between the mounting base and the coupling portion;   a third immobile grating film applied over the third optical array sensor;   a third light source; and   a third mobile grating film interconnected with the middle portion, wherein the third light source emits light that transmits through the third mobile grating film, then through the third immobile grating film, and then to the third optical array sensor.   
     
     
         19 . The load cell of  claim 16 , wherein the support structure comprises a fifth wheel, and wherein the coupling portion pivotably supports the fifth wheel. 
     
     
         20 . The load cell of  claim 14 , wherein the mounting base portion, the coupling portion and the middle portion are an integral, single piece.