Low cost transmitter with calibration means for use in position measurement systems

• US 6,618,133 B2
• Filed: 07/26/2002
• Issued: 09/09/2003
• Est. Priority Date: 03/22/1999
• Status: Expired due to Term

• Current Assignee: 7D Kinematic Metrology Inc.
• Original Assignee: Arc Second, Inc. (Nikon Corporation)
• Inventors: Casteel, Scott, Pratt, Timothy, Cuff, Thomas, Slater, Rick, Hedges, Thomas M., Todd, Donald
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US10/205,956
• Publication Number:
  US 20030025902A1
• Time in Patent Office: 410 Days
• Field of Search: 356/141.4, 356/4.08, 356/141.5
• US Class Current: 356/141.4
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105
• CPC Class Codes: G01S 1/54 Narrow-beam systems producing at a receiver a pulse-type envelope signal of the carrier wave of the beam, the timing of which is dependent upon the angle between the direction of the receiver from the beacon and a reference direction from the beacon; Overlapping broad beam systems defining a narrow zone and producing at a receiver a pulse-type envelope signal of the carrier wave of the beam, the timing of which is dependent upon the angle between the direction of the receiver from the beacon and a reference direction from the beacon
• CPC Class Codes: G01S 1/7032 Transmitters
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves
• CPC Class Codes: G06Q 10/08 Logistics, e.g. warehousing, loading or distribution; Inventory or stock management

Abstract

An improved, low-cost optical transmitter and method useful in a three-dimensional measurement system wherein a plurality of operational parameters of said transmitter are calibrated during manufacture/assembly process to generate unique calibration data for each optical transmitter including data defining angles of each transmitter'"'"'s first and second radiant fan beams and the angle between the beams when the transmitter is leveled for operation in the system and wherein a detector/receiver in the system distinguishes between radiant beams from a plurality of individual transmitters operable within a given measurement field as a function of the selectively alterable rotational velocity calibration data for each of said transmitters and wherein said angular calibration data for each transmitter is operationally available to each detector/receiver operable in the system.

Claims

1. A method for facilitating generation of x-y-z position data within a measurement field wherein at least two rotatably supported optical transmitters are positioned at predetermined locations in a spaced apart relationship to illuminate said measurement field and at least one illumination detector is used to detect illumination from said transmitters, the method comprising the steps of:

propagating first and second substantially planar shaped beams from each transmitter to sweep said measurement field;

propagating an azimuth reference signal for said beams;

selectively positioning said illumination detector within said measurement field;

storing calibration data unique to each transmitter in a memory unit that is associated with that transmitter and not disposed in or physically connected to said illumination detector, said calibration data defining a relative position of said beams of that associated transmitter;

outputting the calibration data to said illumination detector or to a system for calculating said x-y-z position data to identify the transmitter; and

calculating said x-y-z position data using said calibration data and detection of said beams and said strobe by said illumination detector.

2. The method of claim 1, wherein storing said calibration data further comprises storing in said memory unit a rotational velocity which uniquely characterizes each transmitter.

3. The method of claim 2, wherein calculating the x-y-z position data further comprises differentiating between said transmitters operating within said measurement field using said stored rotational velocity calibration data for each of said transmitters.

4. The method of claim 1, wherein calculating the x-y-z position data further comprises calculating differential timing measurements between said azimuth reference signal and said fan beams for each revolution of each said transmitter.

5. The method of claim 1, wherein calculating x-y-z position data further comprises solving for the value of p in a matrix equation represented as

6. A. The method of claim 5, wherein solving said matrix equation further comprises employing a least squares reduction mathematical process.

7. The method of claim 5, wherein solving said matrix equation further comprises employing a single value decomposition mathematical process.

8. The method of claim 1, further comprising changing said calibration data.

9. The method of claim 1, wherein said calculating said x-y-z position data comprises calculating scan angles of said beams each time one of said beams illuminates said illumination detector from which x-y-z data corresponding to a position of said illumination detector may be calculated.

10. A method of manufacturing and marketing a transmitter for use in a position measurement system that generates x-y-z data within a measurement field, wherein said system including means for calculating the x-y-z data at any point in the measurement field using beams from a plurality of optical transmitters, the method comprising:

forming said transmitter with at least one radiation source for generating at least one planar beam that is rotated to sweep said measurement field and a strobe for generating a strobe pulse at a predetermined point in the rotation of said at least one planar beam;

generating calibration data for said transmitter prior to completing manufacture of said transmitter;

storing said calibration data in a memory unit associated with said transmitter; and

selling said transmitter and memory unit as a unit following manufacture and assembly.

11. The method of claim 10, wherein said memory unit is incorporated into said transmitter.

12. The method of claim 10, wherein said calibration data comprises a relative position of planar beams generated by the transmitter.

13. The method of claim 10, wherein said calibration data comprises a rotational speed of said planar beam.

14. An optical transmitter system for use in a position measurement system that generates x-y-z data within a measurement field, said system including means for calculating the x-y-z data at any point in the measurement field using beams from a plurality of rotatably supported optical transmitters,

the optical transmitter comprising:

at least one radiation source that generates at least one rotating substantially fan shaped beam; and

a strobe that generates a strobe pulse at a predetermined point in the rotation of said at least one fan shaped beam; and

a memory unit, in communication with said optical transmitter, containing calibration data unique to said optical transmitter, wherein said memory unit is not physically connected or incorporated in said means for calculating the x-y-z data.

15. The transmitter of claim 14, wherein said memory unit further comprises an output port for outputting the calibration data to said means for calculating the x-y-z data.

16. The transmitter of claim 14, further comprising a wireless communication link between said memory unit and said optical transmitter.

17. The transmitter of claim 14, further comprising a wired electrical communication link between said memory unit and said optical transmitter.

18. The transmitter of claim 14, wherein said memory unit further comprises means for inputting the calibration data to said means for calculating the x-y-z data.

19. The transmitter of claim 14, wherein said calibration data defines a relative position of the fan beams generated by the optical transmitter.

20. An optical transmitter for use in a position measurement system that generates x-y-z data within a measurement field, said system including means for calculating the x-y-z data at any point in the measurement field using beams from a plurality of rotatably supported optical transmitters, the optical transmitter comprising:

at least one optical source that generates at least one rotating substantially fan shaped beam;

a strobe that generates a strobe pulse at a predetermined point in the rotation of said at least one fan shaped beam;

a memory, disposed in said optical transmitter, containing calibration data unique to said transmitter, said calibration data defining a relative position of the fan beams generated by the optical transmitter; and

an output port for outputting the calibration data to identify the transmitter.

21.The optical transmitter of claim 20, wherein said calibration data defines at least one of an angular separation between said laser and a tilt angle for each of said fan beams measured from a vertical axis of said transmitter.

21. The optical transmitter of claim 20, wherein said strobe defines a zero reference for the rotation of said transmitter.

22. The optical transmitter of claim 20, wherein the calibration data further includes data that uniquely defines a rotational velocity of the transmitter.

24. The optical transmitter of claim 20, wherein said means for calculating said x-y-z data comprise a matrix calculation means wherein matrix notation for said calculation can be represented as follows:

25. The optical transmitter of claim 20, wherein said output port is a wireless data port for communicating said calibration data to another device within said position measuring system.

23. The optical transmitter of claim 23, wherein said rotational velocity calibration data is unique for each transmitter in the system and enables the means for calculating x-y-z data to differentiate between transmitters operating within said measurement field.

26. An optical transmitter for a position measuring system that generates x-y-z data within a defined measurement field, said transmitter comprising:

a radiation source for generating a pair of substantially fan shaped beams;

a motor for rotating said fan beams to sweep said measurement field at a predetermined rotational velocity;

a reference signal source for propagating an azimuth reference signal at predetermined intervals of rotation of said fan beams;

a memory unit, physically associated with said transmitter, containing calibration data defining a relative position of the fan beams generated by the optical transmitter and unique to that transmitter; and

an output port for outputting the calibration data to identify the transmitter to another device within said position measuring system.

27. The optical transmitter of claim 27, wherein said output port is a wireless data port.

28. The optical transmitter of claim 27, further comprising a velocity control for selectively controlling said motor to selectively alter the rotational velocity of said fan beams.

30. The optical transmitter of claim 27, wherein said memory unit comprises a digital memory that stores calibration data which defines an angular separation between said fan beams and a vertical tilt angle for each fan beam unique to said transmitter.

31. The optical transmitter of claim 27, wherein the memory unit also stores calibration data including said rotational velocity of said fan beams.

32. The optical transmitter of claim 27, wherein said reference signal defines a beginning reference for the rotation of said fan beams.

29. The optical transmitter of claim 29, wherein said velocity control comprises a rotary transformer controllable by phase-locked loop feedback means.

33. The optical transmitter of claim 29, wherein said velocity control comprises a programmable logic gate array.

34. An optical transmitter for use in a position measurement system that generates x-y-z data within a measurement field, said system including means for calculating the x-y-z data at any point in the measurement field using beams from a plurality of rotatably supported optical transmitters, the optical transmitter comprising:

at least one radiation source that generates at least one rotating substantially fan shaped beam;

a strobe that generates a strobe pulse at a predetermined point in the rotation of said at least one fan shaped beam; and

a memory unit, connected to said optical transmitter, containing calibration data uniquely defining a relative position of the fan beams generated by the optical transmitter.

35. The transmitter of claim 35, wherein said memory unit further comprises an output port for outputting the calibration data to said means for calculating the x-y-z data.

36. The transmitter of claim 35, wherein said connection between said memory unit and said optical transmitter is an electrical connection.

37. The transmitter of claim 35, wherein said connection between said memory unit and said optical transmitter is an physical, non-electrical connection.

38. The transmitter of claim 35, wherein said memory unit further comprises means for inputting the calibration data to said means for calculating the x-y-z data.