System for sensing shaft displacement and strain
First Claim
1. A system for analyzing nonrotational movement of a moving shaft having a central longitudinal axis and having a first set of grid lines spaced about its circumference formed at a first angle to the central longitudinal axis and a second set of grid lines spaced about its circumference and formed at a second angle different from the first angle, comprising:
- first and second optical detection means mountable at fixed positions proximate to the first and second sets of grid lines respectively, for detecting the passage of lines at said first and second angles respectively and producing output signals varying with movement of the grid lines relative to optical grid images generated by the optical detection means; and
processing circuit means connected to said first and second optical detection means for receiving said output signals and generating an output indicative of at least one of displacement of the central longitudinal axis of the shaft and displacement of the shaft along its central longitudinal axis, at a location of said first and second sets of grid lines.
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Abstract
A system detects relative movement between an optical sensor unit and a set of finely spaced, parallel grid lines. Unlike prior optical line detection systems, each set of lines is applied to a surface of an object at an angle relative to movement between the optical sensor unit and the object. The system is particularly useful for monitoring rotating members, such as shafts, but is also useful with linearly moving members. In a preferred shaft monitoring application, a plurality of optical units are provided, with a plurality of corresponding sets of parallel lines at different angles on the shaft. Signal output phase differences between the optical units are compared to precisely determine movement of the shaft in seven directions of freedom, including rigid body displacement components along three translational and three rotational axes, and shaft twist. The differentially angled sets of lines may be spaced axially along the shaft or other object, or a plurality of angled line sets may be superimposed in a single location as a set of cross-hatched lines.
118 Citations
33 Claims
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1. A system for analyzing nonrotational movement of a moving shaft having a central longitudinal axis and having a first set of grid lines spaced about its circumference formed at a first angle to the central longitudinal axis and a second set of grid lines spaced about its circumference and formed at a second angle different from the first angle, comprising:
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first and second optical detection means mountable at fixed positions proximate to the first and second sets of grid lines respectively, for detecting the passage of lines at said first and second angles respectively and producing output signals varying with movement of the grid lines relative to optical grid images generated by the optical detection means; and processing circuit means connected to said first and second optical detection means for receiving said output signals and generating an output indicative of at least one of displacement of the central longitudinal axis of the shaft and displacement of the shaft along its central longitudinal axis, at a location of said first and second sets of grid lines. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A system for analyzing nonrotational movement of a moving shaft having a central longitudinal axis, the shaft having a first set of parallel grid lines spaced about its circumference at a first location, formed at a first angle relative to the central longitudinal axis, and a second set of parallel grid lines at a second location axially spaced from the first location and formed at a second angle different from the first angle, comprising:
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first and second optical detection means mountable at fixed positions proximate to the grid lines at the first and second locations respectively, for detecting the passage of lines at the first angle and second angle respectively and producing output signals varying with movement of the grid lines relative to optical grid images generated by the optical detection means; and processing circuit means connected to said first and second optical detection means for receiving said output signals and generating an output indicative of at least one of displacement of the central longitudinal axis of the shaft and displacement of the shaft along its central longitudinal axis, at said axial locations. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
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25. A system for analyzing nonrotational movement of a moving shaft having a central longitudinal axis, the shaft having a first set of parallel grid lines spaced about its circumference at a first location, formed at an angle relative to the central longitudinal axis, and a second set of parallel grid lines at a second location axially spaced from the first location and formed at the same said angle, comprising:
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first and second optical detection means mountable at fixed positions proximate to the grid lines at the first and second locations respectively, for detecting the passage of lines and producing output signals varying with movement of the grid lines relative to optical grid images generated by the optical detection means; and processing circuit means connected to said first and second optical detection means for receiving said output signals, measuring a phase difference thereof, and generating an output indicative of axial strain of the shaft between said axial locations based on said phase difference.
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26. A system for measuring nonrotational movement of a shaft having an axis of rotation and having at least one set of grid lines spaced about its circumference in at least one location, comprising:
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a plurality of optical detection subsystems mountable in a fixed position proximate to said shaft and near said grid line location for producing an output signal varying with movement of the grid lines relative to said optical detection means, each said optical detection subsystem comprising incoherent radiation energy generation means for producing incoherent radiation energy and directing it against the grid lines;
a Ronchi grid having a plurality of radiation passage lines with spacing corresponding to the grid lines;
lens means for imaging a radiation image scattered from the shaft grid lines onto the plane of said Ronchi grid; and
photodetection means for detecting the radiation level passing through said Ronchi grid means and generating an output signal representative of the movement of the grid lines; andprocessing circuit means connected to said optical detection subsystems for receiving said output signals and generating an output signal indicative of at least one of displacement of the shaft axis and shaft displacement along the shaft axis, relative to the locations of said optical detection subsystems. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33)
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Specification