SURVEYING INSTRUMENT AND METHOD OF CONTROLLING A SURVEYING INSTRUMENT

• US 20080004808A1
• Filed: 06/25/2007
• Published: 01/03/2008
• Est. Priority Date: 07/03/2006
• Status: Active Grant

• Current Assignee: Trimble AB (Trimble Inc.)
• Original Assignee: Trimble AB (Trimble Inc.)
• Inventors: Johnson, Johan, Utterback, Anneli
• Granted Patent: US 7,640,068 B2
• Time in Patent Office: Days
• US Class Current: 702/1
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 3/784 using a mosaic of detectors
• CPC Class Codes: G01S 7/4811 common to transmitter and receiver

Abstract

A surveying instrument performs tracking of a target by controlling an orientation of a measuring unit relative to the target in two different angular directions. The control in one angular direction is based on detected light intensities which are modulated according to a first time pattern, and control of the orientation in the other angular direction is based on detected light intensities modulated according to a second time pattern just different from the first time pattern.

Claims

1. A method of controlling a surveying instrument, the surveying instrument comprising:

a base, a measuring unit mounted relative to the base, and an actuator control unit for controlling an orientation of the measuring unit relative to the base, the measuring unit comprising a lens and a detector having plural detector segments;

the method comprising;

receiving first light through the lens and forming a first spot of the first light on the detector, wherein the first light is modulated light having an intensity which is modulated according to a first time pattern;

receiving second light through the lens and forming a second spot of the second light on the detector, wherein the second light is modulated light having an intensity which is modulated according to a second time pattern;

processing light intensity signals produced by the plural detector segments based on the first and second time patterns and generating a first control signal indicative of a position of the first spot on the detector, and a second control signal indicative of a position of the second spot on the detector;

controlling, in a first control mode, the actuator control unit to change the orientation of the measuring unit relative to the base in a first angular direction based on the first signal and to change the orientation of the measuring unit relative to the base in a second angular direction based on the second signal.

2. The method according to claim 1, wherein the measuring unit comprises a first light source for generating light modulated according to the first time pattern, and wherein

the method further comprises:

emitting the light generated by the first light source towards a reflector and receiving light reflected from the reflector as the first light.

3. The method according to claim 1, wherein the second light is generated by a second light source disposed at a distance from the measuring unit.

4. The method according to claim 3, wherein the second light source is mounted on a pole.

5. The method according to claim 2, wherein the second light is generated by a second light source disposed at a distance from the measuring unit, wherein the second light source is mounted on a pole and wherein the reflector is mounted on the pole.

6. The method according to claim 5, wherein the second light source is disposed at a distance from a center of the reflector.

7. The method according to claim 1, wherein the controlling of the actuator control unit is performed such that at least one of the first and second spots covers a portion of a first detector segment and a portion of a second detector segment adjacent to the first detector segment.

8. The method according to claim 7, wherein the controlling of the actuator control unit is performed such that an intensity of the at least one of the first and second spots incident on the portion of the first detector segment is substantially equal to an intensity of the at least one of the first and second spots incident on the portion of the second detector segment.

9. The method according to claim 1, wherein the detector comprises four adjacent detector segments, wherein the controlling of the actuator control unit is performed such that at least one of the first and second spots covers a portion of each of the four detector segments.

10. The method according to claim 9, wherein the controlling of the actuator control unit is performed such that intensities of the at least one of the first and second spots on each of the four detector segments are substantially equal.

11. The method according to claim 9, wherein the controlling of the actuator control unit is performed such that one of the at least one of the first and second spots covers the portions of the four detector segments and another one of the at least one of the first and second spots covers two detector elements.

12. The method according to claim 2, wherein the detector comprises four adjacent detector segments, wherein the controlling of the actuator control unit is performed such that one of the first and second spots covers the portions of the four detector segments and another one of the first and second spots covers two detector elements, and wherein the one spot covering the four detector segments is formed of light generated by the first light source.

13. The method according to claim 3, wherein the detector comprises four adjacent detector segments, wherein the controlling of the actuator control unit is performed such that one of the first and second spots covers the portions of the four detector segments and another one of the first and second spots covers two detector elements, and wherein the other spot covering the two detector segments is formed of light generated by the second light source.

14. The method according to claim 1, wherein the plural detector segments comprise a central group of detector segments disposed in a central region of the detector, and a peripheral group of detector segments disposed in a peripheral region of the detector, and wherein the controlling of the actuator control unit to change the orientation of the measuring unit relative to the base is, in the first control mode, performed in dependence on light intensities detected by only the detector segments of the central group of detector segments.

15. The method according to claim 1, wherein the method further comprises:

controlling, in a second control mode, the actuator control unit to change the orientation of the measuring unit relative to the base in both the first and second angular directions based on the second signal.

16. The method according to claim 15, wherein the plural detector segments comprise a central group of detector segments disposed in a central region of the detector, and a peripheral group of detector segments disposed in a peripheral region of the detector, and wherein the controlling is performed according to the second control mode when at least one of the first and second spots covers a portion of at least one detector segment of the peripheral group.

17. The method according to claim 16, wherein the controlling is performed according to the first control mode when at least one of the first and second spots covers a portion of at least one detector segment of the central group.

18. The method according to claim 16, wherein the controlling is performed according to the first control mode when both of the first and second spots cover a portion of at least one detector segment of the central group.

19. The method according to claim 1, wherein at least one of the first light and the second light is modulated at a predetermined frequency.

20. The method according to claim 19, wherein the processing of the light intensity signals comprises quadrature processing.

21. The method according to claim 1, further comprising performing a distance measurement using measuring light emitted by the measuring unit.

22. The method according to claim 2, further comprising performing a distance measurement using measuring light emitted by the measuring unit and detecting measuring light reflected from the reflector.

24. A surveying instrument configured to perform the method as defined in claim 1.

27. A computer-readable carrier containing information representing a program adapted to cause a control system of a surveying instrument to execute the method according to claim 1.

23. A surveying instrument comprising:

a base;

a measuring unit mounted relative to the base, the measuring unit comprising a lens and a detector having plural detector segments;

a actuator control unit for controlling an orientation of the measuring unit relative to the base; and

a control system for controlling the actuator control unit, wherein the control system is configured for processing light intensity signals produced by the plural detector segments based on first and second time patterns and generating a first control signal indicative of a position of a first spot of first light on the detector, and a second signal indicative of a position of a second spot of second light on the detector; and

wherein the control system is further configured for controlling, in a first control mode, the actuator control unit to change the orientation of the measuring unit relative to the base in a first angular direction based on the first signal and to change the orientation of the measuring unit relative to the base in a second angular direction based on the second signal.

25. The surveying instrument according to claim 23, further comprising a distance measuring unit.

26. The surveying instrument according to claim 23, wherein the detector is a four-quadrant type detector.