Optoelectronic angle sensor and method for determining a rotational angle about an axis
The invention relates to an optoelectronic angle sensor ( 1 a ) for determining a rotational angle about an axis ( 6 ), comprising a circular disk ( 2 a ) that can be rotated about the axis. Said circular disk comprises a coding, essentially over the entire surface, a flat photosensitive detector ( 3 a ), a device for producing an evaluable image of the coding on the detector and a memory and evaluation component ( 4 a ) for determining the rotational angle. A largely complete, or in particular an entire image of the coding is produced on the detector. The rotational angle is determined using a parameter-varying stochastic comparison method, from the image and a parameterised electronic reference pattern that is provided by means of the memory and evaluation component.
1. An optoelectronic angle sensor for determining a rotational angle about an axis, comprising:
a circular disc rotatable about the axis and having a coding substantially over the whole area;
a planar photosensitive detector, the circular disc and the detector being moveable relative to one another;
a device for producing an evaluable image of the coding on the detector in such a way that the evaluable image comprises information about the relative position of circular disc and detector; and
a memory and evaluation component for determining the rotational angle, wherein:
the device produces a substantially complete image of the coding and the memory and evaluation component;
provides a configured electronic reference pattern which can be coordinated with the coding; and
determines the rotational angle from said reference pattern and said substantially complete image by means of a parameter-varying stochastic comparison method.
2. An optoelectronic angle sensor according to claim 1 , wherein the device:
produces an entire image of the coding and the memory and evaluation component; and
provides a configured electronic model-based reference pattern which can be coordinated with the coding.
3. An optoelectronic angle sensor according to claim 1 , wherein the substantially complete image has at least 50% of the coding.
4. An optoelectronic angle sensor according to claim 1 , wherein the substantially complete image has more than 75% of the coding.
5. An optoelectronic angle sensor according to claim 1 , wherein the substantially complete image has 100% of the coding.
6. An optoelectronic angle sensor according to claim 1 , wherein the areas of detector and circular disc are adapted to one another in their dimensioning.
7. An optoelectronic angle sensor according to claim 1 , wherein the areas of detector and circular disc substantially coincide in their dimensioning.
8. An optoelectronic angle sensor according to any of claim 1 , wherein the circular disc and the detector are arranged so as to be coaxially centered.
9. An optoelectronic angle sensor according to claim 1 , wherein the reference pattern is configured with a reference rotational angle which describes the rotational position of the reference pattern relative to the substantially complete image.
10. An optoelectronic angle sensor according to claim 1 , wherein the reference pattern is based on: a mathematical model of the substantially complete image or of the coding; or a reproducing duplication or simulation of the substantially complete image or of the coding.
11. An optoelectronic angle sensor according to claim 1 , wherein the comparison method uses a:
estimation method; or
mathematical correlation method.
12. An optoelectronic angle sensor according to claim 1 , wherein the comparison method uses a maximum likelihood method or least squares method.
13. An optoelectronic angle sensor according to claim 1 , wherein the comparison method has a radial weighting of coding components.
14. An optoelectronic angle sensor according to claim 1 , wherein the coding has a:
code variable in an angle-dependent manner both in the azimuthal and in the radial direction; and/or
incremental code; and/or
point code distributed in a polar manner; and/or
absolute code; and/or
azimuthally extending radial code,
as a part-code.
15. A method for determining a rotational angle about an axis, using a circular disc rotatable about the axis and having a coding substantially over the whole area and a planar photosensitive detector the circular disc and the detector being moveable relative to one another, the method comprising:
producing a substantially complete evaluable image of the coding on the detector in a manner such that the image comprises information about the relative position of circular disc and detector;
provisioning an electronic reference pattern which can be varied in configuration by at least one parameter and can be coordinated with the coding; and
deriving the rotational angle by comparison of said reference pattern and said substantially complete evaluable image and by a parameter-varying stochastic comparison method, wherein the method is performed using an optoelectronic angle sensor according to claim 1 .
16. The method according to claim 15 , wherein an entirely complete evaluable image is produced.
17. The method according to claim 15 , wherein the reference pattern is provided: as a mathematical model of the substantially complete evaluable image; as a mathematical model of the coding; as an algorithmic description of the substantially complete evaluable image; as an algorithmic description of the coding; as an image-reproducing simulation or duplication; or as a coding-reproducing simulation or duplication.
18. The method according to claim 15 , wherein the reference pattern and the substantially complete evaluable image are digitally superposed in the comparison.
19. The method according to claim 15 , wherein an:
estimation method, in particular maximum likelihood method or least squares method; or
mathematical correlation method, is used in the derivation.
20. The method according to claim 15 , wherein:
a reference rotational angle which describes the rotational position of the reference pattern relative to a mapping is chosen as the parameter;
a parameter estimation is carried out by a maximum likelihood method; and the rotational angle is determined as an estimated parameter.