Method of mobile radio positioning aided by single fan self-surveying laser transmitter

• US 20080192242A1
• Filed: 12/17/2007
• Published: 08/14/2008
• Est. Priority Date: 12/11/2004
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Nichols, Mark E.
• Granted Patent: US 7,808,626 B2
• Time in Patent Office: Days
• US Class Current: 356/139.01
• CPC Class Codes: G01S 19/04 providing carrier phase data
• CPC Class Codes: G01S 19/10 providing dedicated supplementary positioning signals
• CPC Class Codes: G01S 19/44 Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method

Abstract

A method of mobile radio positioning aided by a single fan self-surveying laser transmitter (SF_SS_LT), wherein a rover comprises a mobile radio positioning system (Mobile_RADPS) integrated with a mobile laser detector; and wherein THE SF_SS_LT comprises a single fan laser transmitter and a positioning system integrated with the single fan laser transmitter. The method comprises: (A) performing self-surveying of the (SF_SS_LT); (B) generating a single fan laser beam by using the single fan laser transmitter; (C) detecting the single fan beam by using the mobile laser detector; and (D) timing the fan laser beam strike at the rover'"'"'s location and using the timing of the fan laser beam strike at the rover'"'"'s location to improve an accuracy in determination of position coordinates of the rover.

Claims

1. A method of mobile radio positioning aided by a single fan self-surveying laser transmitter (SF_SS_LT), wherein a rover comprises a mobile radio positioning system (Mobile_RADPS) integrated with a mobile laser detector;

and wherein said SF_SS_LT comprises a single fan laser transmitter and a positioning system integrated with said single fan laser transmitter;

wherein said positioning system is configured to obtain the coordinate measurements of said single fan laser transmitter;

said method comprising;

(A) performing self-surveying of said (SF_SS_LT);

(B) generating a single fan laser beam by using said single fan laser transmitter;

(C) detecting said single fan beam by using said mobile laser detector; and

(D) timing said fan laser beam strike at said rover'"'"'s location and using said timing of said fan laser beam strike at said rover'"'"'s location to improve an accuracy in determination of position coordinates of said rover.

2. The method of claim 1, wherein said step (A) further comprises:

(A1) providing a stationary radio positioning system (RADPS) receiver integrated with said single fan laser transmitter, said stationary RADPS receiver having a stationary radio antenna;

wherein the distance between a phase center of said stationary radio antenna and said single fan laser transmitter is known and fixed;

(A2) providing a wireless communication device configured to receive a set of differential corrections data; and

(A3) obtaining precise coordinate measurements of said single laser transmitter by using said stationary radio positioning system (RADPS) receiver configured to utilize said set of differential corrections data.

3. The method of claim 1, wherein said step (B) further comprises:

(B1) mechanically rotating said fan laser transmitter head about its vertical axis at a substantially constant angular rate.

4. The method of claim 3, wherein said step (B1) further comprises:

(B1,

     1) controlling said substantially constant angular rate of said rotation of said fan laser transmitter head about its vertical axis by using a phase oscillator.

5. The method of claim 3, wherein said step (B1) further comprises:

(B1,

     2) enhancing said substantially constant angular rate of said rotation of said fan laser transmitter head about its vertical axis by giving said laser transmitter head a substantially sufficient mass.

6. The method of claim 1, wherein said step (B) further comprises:

(B2) optically rotating said fan laser transmitter about its vertical axis at said substantially constant angular rate.

7. The method of claim 1, wherein said step (B) further comprises:

(B3) generating an electronic timing pulse every time a known position of said laser beam passes a single reference mark in said laser transmitter;

(B4) generating a plurality of time tags by time-tagging each said electronic timing pulse by using said SF_SS_LT;

(B5) generating a low-passed filtered estimate of an angular rate of said laser beam by using said plurality of time tags;

wherein each said time tag is indicative of a time instant when said reference mark is crossed by one said electronic timing pulse; and

(B6) transmitting said low-passed filtered estimate of angular rate of said laser beam and transmitting said plurality of time tags to said rover via said wireless communication link.

8. The method of claim 1, wherein said step (B) further comprises:

(B7) generating a main electronic timing pulse every time a known position of said laser beam passes a main reference mark;

(B8) generating an additional electronic timing pulse every time a known position of said laser beam passes an additional reference mark;

(B9) generating a plurality of main time tags by time-tagging each said main electronic timing pulse by using said SF_SS_LT;

(B10) generating a plurality of additional time tags by time-tagging each said additional electronic timing pulse by using said SF_SS_LT;

(B11) generating a first low-passed filtered estimate of an angular rate of said laser beam by using said plurality of main time tags;

wherein each said main time tag is indicative of a time instant when said main reference mark is crossed by one said main electronic timing pulse;

(B12) generating a second low-passed filtered estimate of an angular rate of said laser beam by using said plurality of additional time tags;

wherein each said additional time tag is indicative of a time instant when said additional reference mark is crossed by one said additional electronic timing pulse;

(B13) averaging said first low-passed filtered estimate of said angular rate of said laser beam and said second low-passed filtered estimate of said angular rate of said laser beam; and

(B14) transmitting said averaged low-passed filtered estimate of angular rate of said laser beam;

transmitting said plurality of main time tags, and transmitting said plurality of additional time tags to said rover via said wireless communication link.

9. The method of claim 1, wherein said step (C) further comprises:

(C1) detecting at least one light pulse generated by said laser transmitter by using said mobile laser detector;

wherein each said light pulse corresponds to one said single sloping fan laser beam strike at said rover'"'"'s location; and

(C2) receiving said low-passed filtered estimate of angular rate of said laser beam and receiving said plurality of time tags.

10. The method of claim 1, wherein said step (C) further comprises:

(C3) detecting at least one light pulse generated by said laser transmitter by using said mobile laser detector;

wherein each said light pulse corresponds to one said single sloping fan laser beam strike at said rover'"'"'s location; and

(C4) receiving said averaged low-passed filtered estimate of angular rate of said laser beam, receiving said plurality of main time tags, and receiving said plurality of additional time tags.

11. The method of claim 1, wherein said step (D) further comprises:

(D1) measuring the time difference between the time instance when said light pulse corresponding to said single sloping fan laser beam strike at said rover'"'"'s location is received and the latest main reference crossing time corresponding to the time instance when said known position of said laser beam passes said main reference mark at the location of said laser transmitter; and

(D2) calculating a height of said rover with improved accuracy based on position coordinates of said rover and based on said time difference measured at said step (D1), wherein said position coordinates of said rover are interpolated position coordinates interpolated between position coordinates taken at GPS time Epoch immediately preceding said laser strike and position coordinates taken at GPS time Epoch immediately after said laser strike.

12. The method of claim 11, wherein said step of (D2) further comprises:

(D2,

     1) providing a differential mobile radio positioning system (Mobile_RADPS);

(D2,

     2) receiving a second plurality of external radio signals broadcasted by at least one radio source selected from the group consisting of;

{GPS;

GLONASS;

combined GPS/GLONASS;

GALILEO;

Global Navigational Satellite System (GNSS); and

a pseudolite transmitter} by using said differential mobile radio positioning system (Mobile_RADPS); and

(D2,

     3) receiving a second set of differential corrections data broadcasted by at least one source selected from the group consisting of;

{a Base Station, an RTK Base Station;

a Virtual Base Station (VBS); and

a pseudolite transmitter} by using said differential mobile radio positioning system (Mobile_RADPS);

wherein said differential mobile radio positioning system (Mobile_RADPS) is configured to utilize said second plurality of external radio signals and said second set of differential corrections data to obtain position coordinates of said rover.

13. The method of claim 11 further comprising:

(D3) optimizing said improved height calculation of said rover.

14. The method of claim 13, wherein said step (D3) further comprises:

(D3,

     1) calculating a set of sensitivity parameters selected from the group consisting of;

{a partial derivative of said rover'"'"'s height with respect to a laser beam rotation frequency;

a partial derivative of said rover'"'"'s height with respect to a horizontal distance from said rover to said laser transmitter;

a partial derivative of said rover'"'"'s height with respect to a time difference between said actual laser strike time and said expected laser strike time; and

a partial derivative of said rover'"'"'s height with respect to a vertical angle}.

15. The method of claim 13, wherein said step (D3) further comprises:

(D3,

     2) calculating said variable laser beam rotation frequency by using said plurality of time tags corresponding to time-tagging of said laser beam to each said additional reference mark at said laser transmitter location.

16. The method of claim 11 further comprising:

(D4) calibrating said improved height calculation of said rover for planar errors affecting the planarity of said single fan beam.

17. The method of claim 1, wherein said rover comprises an implement, wherein said implement is selected from the group consisting of:

{a blade or a bucket on an earthmoving machine;

an agricultural implement; and

a device connected to a machine, wherein the device'"'"'s location is being controlled};

said method further comprising;

(E) determining position coordinates of said implement with improved accuracy.

18. The method of claim 17, wherein said step (E) further comprises:

(E1) sending to said SF_SS_LT position coordinates of said implement.

19. The method of claim 1, wherein said SF_SS_LT further comprises a display unit;

said method further comprising;

(F) displaying position coordinates of said implement.

20. The method of claim 1 further comprising:

(G) controlling the movement of said implement.