Measuring method for an articulated-arm coordinate measuring machine

Patent metadata

Field	Value
Publication number	US-9080867-B2
Application number	US-93742309-A
Country	US
Kind code	B2
Filing date	Apr 17, 2009
Priority date	Apr 22, 2008
Publication date	Jul 14, 2015
Grant date	Jul 14, 2015

Abstract

A measuring method for determining a measurement position of a probe element 6 can include using a coordinate measuring machine 1 having a base and members that can be moved relative to the base and relative to each other, wherein one of the members, as the probe member TG, comprises a probe element 6 , so that the probe element 6 can move freely within a prescribed volume of space, wherein the measurement position is captured by the probe element 6 , a measurement variable set is taken by measuring measurement variables linked to a measurement position of the members, wherein the measurement position is determined by a relative location of the members to each other and of at least one of the members to the base, and the measurement position is determined relative to the base.

First claim

We claim:

1. A measuring method for determining a measuring position of a probe element with the aid of a coordinate measuring machine, the coordinate measuring machine having a base, and a plurality of members that can be moved relative to the base and relative to one another, one of the members having, as a probe member, the probe element, such that the probe element can be moved freely within a prescribed space volume, the method comprising:
adopting the measuring position by the probe element;
measuring by the coordinate measuring machine with the aid of position measuring device positions of the members relative to one another, as measurement variables linked to a measurement setting of the members, the measurement setting being determined by a relative position of the members to one another, and of at least one of the members relative to the base so as to acquire a set of measurement variables; and
determining the measuring position relative to the base by the coordinate measuring machine, wherein:
in a spatially fixed state of the probe element in the measuring position a plurality of different measurement settings are generated, the acquisition respectively being performed anew for these such that at least one set of measurement variables is recorded for each measurement setting; and
the determination is performed with the aid of a statistical evaluation of the recorded sets of measured variables,

wherein the different measurement settings are generated by a repeated changing of the relative position of at least two of the members relative to one another and/or of the relative position of at least two of the members relative to the base.

2. The measuring method as claimed in claim 1 , wherein a compensation calculation is performed as statistical evaluation for the recorded sets of measurement variables.

3. The measuring method as claimed in claim 1 , wherein a compensation calculation is performed as statistical evaluation for the recorded sets of measurement variables with the aid of the method of least squares, and/or an optimized statistical estimation method is applied for the statistical evaluation.

4. The measuring method as claimed in claim 1 , wherein the different measurement settings are generated by a repeated changing of the relative position of at least two of the members relative to one another and/or of the relative position of at least two of the members relative to the base, the repeated changing being carried out by an exertion of a variant force on at least one point of action on one of the members manually via a user.

5. The measuring method as claimed in claim 1 , wherein an angle and/or a distance of the members to/from one another, and of at least one of the members relative to the base are respectively measured as the measurement variables.

6. The measuring method as claimed in claim 1 , wherein in order to fix the probe element spatially a relative position of the probe member in space is maintained during the measurement.

7. The measuring method as claimed in claim 1 , wherein in order to fix the probe element spatially a relative position of the probe member in space is maintained during the measurement manually by a user.

8. The measuring method as claimed in claim 1 , wherein an accuracy value for the determination of the measuring position is derived statistically.

9. The measuring method as claimed in claim 1 , wherein a changing of the measurement settings and the acquisition of the sets of measurement variables are performed continuously within a measurement period.

10. The measuring method as claimed in claim 9 , wherein the acquisition is performed with a specific frequency, the changing of the measurement settings being performed by producing continuous movements of a plurality of the members.

11. The measuring method as claimed in claim 10 , wherein the changing of the measurement settings is performed by producing continuous movements of a plurality of the members with many movement reversals.

12. The measuring method as claimed in claim 9 , wherein the measurement period is elected that a prescribed statistical minimum accuracy for the determination of the measuring position is achieved.

13. The measuring method as claimed in claim 9 , wherein a measurement stop signal is indicated at the end of the measurement period in an optical, acoustic and/or tactile fashion.

14. The measuring method as claimed in claim 1 , wherein a specific number of different measurement settings are generated, the number being selected such that a prescribed statistical minimum accuracy for the determination of the measuring position is achieved.

15. The measuring method as claimed in claim 1 , wherein a specific number of different measurement settings are generated, the number being selected such that a prescribed statistical minimum accuracy for the determination of the measuring position is achieved, a measurement stop signal being indicated in an optical, acoustic and/or tactile fashion after achievement of the specific number of different measurement settings.

16. The measuring method as claimed in claim 1 , wherein the probe element is designed for making tactile contact with a measuring point of a measurement object surface, as a result of which the measuring position is adopted.

17. The measuring method as claimed in claim 16 , wherein the spatial fixing of the probe element is performed by maintaining a tactile contact between the probe element and the measuring point.

18. The measuring method as claimed in claim 1 , wherein the probe element is designed for optically measuring a measuring point of a measurement object surface, or the probe element is designed for optically scanning or acquiring a measurement object surface.

19. A computer program product with program code, which is stored on a non-transitory machine readable medium, for carrying out the steps of:
renewed acquisition of a set of measurement variables for the different measurement settings in each case; and
determination of the measuring position of the probe element with the aid of a statistical evaluation of the recorded sets of measurement variables of the method as claimed in claim 1 when the program is executed in an evaluation unit.

20. A coordinate measuring machine for determining a measuring position of a probe element, comprising:
a base;
a plurality of members that can be moved relative to the base and relative to one another, one of the members having the probe element as probe member such that the probe element can be moved within a prescribed space volume;
a plurality of position measuring devices for measuring measurement variables that depend on a measurement setting of the members, the measurement setting being given by a relative position of the members to one another, and at least one of the members being given relative to the base; and
an evaluation unit for determining the measuring position, wherein the evaluation unit is designed for continuously acquiring, in the course of a determination of position, a plurality of sets of measurement variables for different measurement settings at a sole, fixed measuring position of the probe element, and the evaluation unit is also designed for deriving the measuring position of the measuring point with the aid of a statistical evaluation of the recorded sets of measured variables,
wherein in a spatially fixed state of the probe element in the measuring position a plurality of different measurement settings are generated, the acquisition respectively being

Assignees

• Lippuner Heinz
• Siercks Knut
• Leica Geosystems Ag

Inventors

• Lippuner Heinz
• Siercks Knut

Classifications

• B25J9/06

  characterised by multi-articulated arms · CPC title

• B25J13/02

  Hand grip control means {(handles or pedals for crane control B66C13/56; for measuring the force applied to control members G01L5/22; hand-held casings for switching devices, e.g. joy-sticks H01H9/0214)} · CPC title

• G01B21/04

  by measuring coordinates of points · CPC title

• G01B21/045 Primary

  Correction of measurements (G01B9/02055 takes precedence) · CPC title

• G01B5/008

  using coordinate measuring machines · CPC title