Measurement apparatus for the absolute determination of lengths and of angles

• US 8,296,964 B2
• Filed: 12/30/2010
• Issued: 10/30/2012
• Est. Priority Date: 02/09/2010
• Status: Expired due to Fees

• Current Assignee: Sick Stegmann GmbH (Sick Management GmbH)
• Original Assignee: Sick Stegmann GmbH (Sick Management GmbH)
• Inventors: Siraky, Josef
• Primary Examiner(s): Bennett, G. Bradley
• Application Number:
  US12/982,134
• Publication Number:
  US 20110192045A1
• Time in Patent Office: 670 Days
• Field of Search: 33/1.PT, 337/06, 337/07, 337/08
• US Class Current: 33/706
• CPC Class Codes: G01D 3/10 with provision for switching-in of additional or auxiliary indicators or recorders
• CPC Class Codes: G01D 5/2454 Encoders incorporating incremental and absolute signals
• CPC Class Codes: G01D 5/2497 Absolute encoders G01D5/2454 takes precedence
• CPC Class Codes: G01D 5/34753 Carriages; Driving or coupling means

Abstract

A measurement apparatus (10) for the absolute value determination of lengths or of angles, said apparatus having at least one reading head (14) and a physical scale (12) is provided, which has at least a partial section (18) with a connection (28) for another partial section (18) in a sequential arrangement. In this respect the partial section (18) includes a control unit (30) for the active determination of the position of the reading head (14) proximal to the partial section (18) as well as a storage element (32) in which an own position information of the partial section (18) within the physical scale (12) can be stored.

Claims

1. A measurement apparatus (10) for the absolute value determination of lengths or of angles, comprising:

said apparatus having at least one reading head (14) and a physical scale (12) which has at least a partial section (18) with a connection (28) for another partial section (18) in a sequential arrangement, wherein the partial section (18) includes a control unit (30) for the active determination of the position of the reading head (14) proximal to the partial section (18) as well as a storage element (32) in which an own position information of the partial section (18) within the physical scale (12) can be stored,

wherein the reading head (14) is configured to generate a respective measurement value for both partial sections (18c) at a transition (34) between two partial sections (18),

and wherein the measurement apparatus (10) comprises means for deriving a correction value for the transition (34) from the difference of the two measurement values.

2. A measurement apparatus (10) in accordance with claim 1 wherein the physical scale (12) is self-configuring in that the control unit (30) is adapted to receive its own position information from a connected other partial section (18) or to derive its own position information from a position information of a connected other partial section (18).

3. A measurement apparatus (10) in accordance with claim 1 wherein the reading head (14) is active and generates a field which interacts with a field (42) generated by the physical scale (12) or, wherein the reading head (14) is passive and modifies a field (42) generated by the physical scale (12) or reflects a field (42) to the physical scale (12).

4. A measurement apparatus in accordance with claim 1 wherein the control unit (30) is configured to generate a field (42) at each position of the partial section (18) to evaluate whether a reading head (14) is present proximal to the partial (18) section and at which position the reading head (14) is proximal to the partial section (18), wherein the result of the evaluation can be emitted via the connection (28).

5. A measurement apparatus (10) in accordance with claim 1 wherein a deviation of its own position measurement of the partial section (18) from a reference is stored in the storage element (32) to calibrate the partial section (18).

6. A measurement apparatus (10) in accordance with claim 1 wherein the physical scale (12) has curved partial sections (18) for an angle measurement.

7. A measurement apparatus (10) in accordance with claim 6 wherein the partial sections (18) can be bent to different radii of curvature.

8. A measurement apparatus (10) in accordance with claim 1 wherein a main control (16) is provided which is electrically connected to the physical scale (12) and is connected to the beginning and the end of the sequential arrangement.

9. A measurement apparatus (10) in accordance with claim 8 wherein the main control (16) is also connected to the actively configured reading head (14).

10. A measurement apparatus (10) in accordance with claim 1 wherein a starting section (20) is provided at the beginning of the sequential arrangement and an end section (22) is provided at the end of the sequential arrangement.

11. A measurement apparatus (10) in accordance with claim 10 wherein the main control (16) is at least partially integrated into the starting section (20) or into the end section (22).

12. A measurement apparatus (10) in accordance with claim 1 wherein the physical scale (12) and the reading head (14) are configured for an inductive measurement, a capacitive measurement or a magnetic measurement of lengths or of angles.

13. A method for the absolute value determination of lengths or of angles having at least one reading head (14) and a physical scale (12) which is formed from a sequential arrangement of partial sections (18), wherein a partial section (18) actively measures the position of the reading head (14) proximal to the partial section (18), wherein the position of the partial section (18) within the sequential arrangement is determined by means of a position information stored in the partial section (18) and wherein the absolute value is determined from the position within the partial section (18) and the position of the partial section (18) within the sequential arrangement

wherein a respective measurement value for both partial sections (18) is generated when the reading head (14) is positioned at a transition (34) between two partial sections (18),

and wherein a correction value for the transition (34) derives from the difference between the two measurement values.

14. A method in accordance with claim 13 wherein the physical scale (12) is self-configured in that, in sequence, each partial section (18) starting with a first partial section assigns itself a position information in a self-configuration mode or is assigned a position information and subsequently places a partial section (18) arranged downstream thereof into the self-configuration mode.

15. A method in accordance with claim 13 wherein the position information of one of the two partial sections (18) is compensated by the correction value.

16. A method in accordance with claim 13 wherein the physical scale (12) is calibrated wherein each partial section (18) stores deviations to a reference value, wherein a zero point (40) for the physical scale (12) is determined, in particular for one of the reading heads (14), and distances at a transition (34) between two partial sections (18) are corrected to the zero point (40) on movement of the reading head (14) across the transition (34).

17. A method in accordance with claim 16 wherein a zero point (40) for one of the reading heads (14) is determined, and distances at a transition (34) between two partial sections (18) are corrected to the zero point (40) on movement of the reading head (14) across the transition (34).

18. A method in accordance with claim 13 wherein for an initial determination of the position of reading heads (14) each location of the physical scale (12) is checked through the generation of a local field (42) by means of position multiplexing to see whether a reading head (14) is present and wherein subsequently in operation only a local field (42) is respectively generated in the vicinity of a reading head (14).