Multiple channel locating

Patent metadata

Field	Value
Publication number	US-9696137-B2
Application number	US-201414455039-A
Country	US
Kind code	B2
Filing date	Aug 8, 2014
Priority date	Jul 8, 2008
Publication date	Jul 4, 2017
Grant date	Jul 4, 2017

Abstract

Methods, systems, and apparatuses are provided for estimating a location on an object in a three-dimensional scene. Multiple radiation patterns are produced by spatially modulating each of multiple first radiations with a distinct combination of one or more modulating structures, each first radiation having at least one of a distinct radiation path, a distinct source, a distinct source spectrum, or a distinct source polarization with respect to the other first radiations. The location on the object is illuminated with a portion of each of two or more of the radiation patterns, the location producing multiple object radiations, each object radiation produced in response to one of the multiple radiation patterns. Multiple measured values are produced by detecting the object radiations from the location on the object due to each pattern separately using one or more detector elements. The location on the object is estimated based on the multiple measured values.

First claim

What is claimed is:

1. A method for estimating coordinates of a location on an object in a 3D scene, the method comprising:
producing one or more radiation patterns varying along at least two directions, wherein the one or more radiations patterns repeat along at least one direction from the at least two directions;
calculating one or more illumination symbols based on the one or more radiation patterns;
illuminating a region of the object with the one or more radiation patterns, wherein the region includes a plurality of locations that includes the location whose coordinates are to be estimated and wherein each illuminated location within the region produces one or more object radiations in response to the one or more radiation patterns;
measuring at least a portion of the one or more object radiations using one or more detector elements to produce a plurality of measured values, wherein measuring at least the portion of the one or more object radiations comprises forming an image of the 3D scene onto one or more camera image sensors such that at least a portion the region of the object including the location whose coordinates are to be estimated is imaged onto two or more pixels on the one or more camera image sensors;
calculating one or more detection symbols from the plurality of measured values;
establishing a correspondence between at least one of the one or more detection symbols and at least one of the one or more illumination symbols, wherein establishing the correspondence between at least one of the one or more detection symbols and at least one of the one or more illumination symbols comprises finding a smallest vector norm of a vector difference between the one or more detection symbols and each of the one or more illumination symbols; and
estimating the coordinates of the location on the object based on the correspondence between the at least one of the one or more detection symbols and the at least one of the one or more illumination symbols.

2. The method of claim 1 , wherein:
the one or more detection symbols are calculated from a subset of pixels on the one or more camera image sensors; and
finding the smallest vector norm comprises:
calculating a cross-correlation between two or more illumination symbols from the one or more illumination symbols and the one or more detection symbols; and
finding a peak cross correlation among the corresponding illumination symbols for each detection symbol.

3. The method of claim 2 , wherein the cross-correlation is calculated using a fast Fourier transform.

4. The method of claim 1 , wherein:
the one or more detection symbols are calculated from a subset of pixels on the one or more camera image sensors;
finding the smallest vector norm comprises:
calculating a cross-correlation between each illumination symbol from the one or more illumination symbols and the one or more detection symbols, and
finding a peak cross-correlation among the one or more detection symbols for each illumination symbol from the one or more illumination symbols; and

establishing the correspondence between at least one of the one or more detection symbols and at least one of the one or more illumination symbols is based on the peak cross correlation.

5. The method of claim 1 , wherein estimating the coordinates of the location on the object comprises:
selecting one or more subsets of elements within the one or more detected symbols;
establishing a second correspondence between each subset of elements within the one or more detection symbols and a subset of elements within the one or more illumination symbols; and
estimating the coordinates of the location on the object for each subset based on the second correspondence.

6. The method of claim 1 , wherein:
the one or more detection symbols are calculated from a contiguous set of pixels on the one or more camera image sensors; and
finding the smallest vector norm comprises:
calculating a cross-correlation between each illumination symbol from the one or more illuminations symbols and the one or more detection symbols;
finding a peak cross-correlation among the one or more detection symbols;
calculating, using the peak cross-correlation, a second detected symbol from a subset of the one or more detectors elements used to calculate the second detection symbol; and
finding a smallest vector norm of the vector difference between the second detection symbol and a second set of illumination symbols from the one or more illumination symbols.

7. The method of claim 1 , wherein:
the one or more detection symbols are calculated from a subset of pixels on the one or more camera image sensors; and
finding the smallest vector norm comprises:
calculating a cross-correlation between a single illumination symbol from the one or more illuminations symbols and the one or more detection symbols; and
finding a peak cross correlation among the one or more detection symbols.

8. The method of claim 1 , wherein at least two radiation patterns from the one or more radiation patterns are projected sequentially, and at least two of the radiation patterns differ by a scaling factor.

9. The method of claim 1 , wherein at least calculating the one or more detection symbols or calculating the one of more illumination symbols comprises at least removing a common offset, removing a common scale factor, or applying a remapping function.

10. A method for estimating coordinates of a location on an object in a 3D scene, the method comprising:
producing one or more radiation patterns varying along at least two directions, wherein the one or more radiations patterns repeat along at least one direction from the at least two directions;
calculating one or more illumination symbols based on the one or more radiation patterns;
illuminating a region of the object with the one or more radiation patterns, wherein the region includes a plurality of locations that includes the location whose coordinates are to be estimated and wherein each illuminated location within the region produces one or more object radiations in response to the one or more radiation patterns;
measuring at least a portion of the one or more object radiations using one or more detector elements to produce a plurality of measured values, wherein measuring at least the portion of the one or more object radiations comprises forming an image of the 3D scene onto one or more camera image sensors such that at least a portion the region of the object including the location whose coordinates are to be estimated is imaged onto two or more pixels on the one or more camera image sensors;
calculating one or more detection symbols from the plurality of measured values, wherein the one or more detection symbols are calculated from a contiguous set of pixels on the one or more camera image sensors;
establishing a correspondence between at least one of the one or more detection symbols and at least one of the one or more illumination symbols, wherein establishing the correspondence between at least one of the one or more detection symbols and at least one of the one or more illumination symbols comprises:
calculating a cross-correlation between two or more illumination symbols from the one or more illumination symbols and one or more of the detection symbols;
calculating, using the peak cross-correlation, a second detected symbol from a subset of the detectors elements used to calculate the second detection symbol; and

finding a smallest vector norm of a vector difference between the second detection symbol and a second set of illumination symbols; and
estimating the coordinates of the location on the object based on the correspondence between the at least one of the one or more d

Assignees

• Cognex Corp

Inventors

• Braker Benjamin
• Moore Eric
• Feldkhun Daniel

Classifications

• G01B11/2536

  using several gratings with variable grating pitch, projected on the object with the same angle of incidence · CPC title

• G01S17/48

  Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves · CPC title

• G01S7/4815

  using multiple transmitters · CPC title

• G01S7/486

  Receivers · CPC title

• G01S7/4818

  using optical fibres · CPC title