Position sensing method and apparatus
First Claim
1. A method of sensing the position of a specularly reflecting, rounded corner of a strongly reflecting object, the method comprising:
- providing an electro-optical sensing device, said sensing device comprising light source means for providing a single static fan beam of light, and light detector means;
said light source means being operative to provide a fan beam of light orientated across the rounded corner of the reflecting object;
said source means and said detector means being positioned such that a relatively large amount of the light reaching said detector means is light reflected from a narrow stripe-shaped region of said object extending along said corner; and
determining with said detector means the amount of light reflected from said object along a linear scale of positions defined relative to the direction of alignment between said source means and said detector means.
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Accused Products
Abstract
A fan beam of light from a source (L) is directed across the edge of a car body window frame section (10) with an external reflective corner (11) and an internal reflective corner (12). The corners reflect sharp spots of light (S1) and (S2) respectively into a detector (D) which produces an output waveform (FIG. 2) in which sharp pulses (P1, P2) correspond to the spots of light. It is easy to discriminate against other pulses (P3) arising from stray reflections, e.g. the multiple reflection (13, R3). The positions of the pulses (P1 and P2) enable the positions of the corners to be calculated. Two detectors and/or or two light sources may be used to increase the amount of data available so as to allow a complete solution for the coordinates of the centers of curvature (C1, C2) of the corners relative to the detectors and the radii of curvature of the corners.
35 Citations
17 Claims
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1. A method of sensing the position of a specularly reflecting, rounded corner of a strongly reflecting object, the method comprising:
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providing an electro-optical sensing device, said sensing device comprising light source means for providing a single static fan beam of light, and light detector means; said light source means being operative to provide a fan beam of light orientated across the rounded corner of the reflecting object; said source means and said detector means being positioned such that a relatively large amount of the light reaching said detector means is light reflected from a narrow stripe-shaped region of said object extending along said corner; and determining with said detector means the amount of light reflected from said object along a linear scale of positions defined relative to the direction of alignment between said source means and said detector means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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- 11. Apparatus for sensing the position of a specularly reflecting, rounded corner with an electro-optical device, characterised in that the device comprises a light source providing a fan beam of light orientated across the corner, a light detector positioned to receive light specularly reflected from the corner, the light detector being of a kind producing an output waveform in which the position of a pulse indicates the position along a linear scale, and computing means responsive to the output waveform to compute a position of the corner relative to the detector and in a detector plane established by the fan beam.
- 14. Automatic assembly apparatus for fitting a component to an object having rounded specularly reflecting corners, comprising a robot with a head for holding the component and programmed to pick up the component in a fixed position relative to the head and move it to a nominal datum position relative to the object, at least one electro-optical device mounted on the head to observe one of the corners of the object, said at least one device comprising a light source and a light detector adapted to enable the position of a reflecting object to be specified as a position along a scale referenced to a direction of alignment of said source and said detector, characterized in that the light source produces a static fan-shaped beam of light or produces a scanning light beam which scans to provide a static fan-shaped beam of light, in that said scale extends in the direction of the fan-shaped beam and across said one corner, and in that the positions of the source and detector are such that a relatively large amount of the light reaching the detector is light reflected from a narrow stripe-shaped region of said object extending along the corner, and by computing means responsive to signals from said at least one device to compute at least one correction signal, and means applying said at least one correction signal to control a corresponding degree of freedom of the robot so as to bring the component accurately to said datum position before the robot fits the component to the object.
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17. A method of sensing the position of a specularly reflecting, rounded corner, the method comprising:
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providing an electro-optical sensing device, said sensing device comprising light source means of a pencil beam of light, illuminating and linearly scanning said light source means in a plane to provide a static fan beam of light orientated across a rounded corner of the reflecting object; said source means and said detector means being positioned such that a relatively large amount of light reaching said detector means is light reflected from a narrow stripe-shaped region of said object extending along said corner; and determining with said detector means the amount of light reflected from said object along a linear scale of positions defined relative to the direction of alignment between said source means and said detector means.
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Specification