Systems and methods for computing vertical position

• US 20120050095A1
• Filed: 08/27/2010
• Published: 03/01/2012
• Est. Priority Date: 08/27/2010
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Scherzinger, Bruno, Vollath, Ulrich
• Granted Patent: US 8,395,542 B2
• Time in Patent Office: Days
• US Class Current: 342/357.3
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/47 the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial

Abstract

Control systems and methods that provide a high degree of vertical measurement accuracy for a body in motion are disclosed. The systems employ an inertial sensor system for vertical measurement and a Global Navigation Satellite System that includes multipath reduction or attenuation to provide corrected vertical information for a moving body to the inertial sensor system. The combination of these systems enables the maintenance of an accurate vertical position for said body.

Claims

1. A system for determining the vertical position of a body in motion, comprising:

a. an inertial measurement unit configured to determine vertical acceleration information for the body in motion;

b. a processor adapted to use said vertical acceleration information to determine an amount of vertical movement of the body and to calculate vertical position information for the body in a predetermined coordinate system; and

c. a GNSS having at least one GNSS receiver, said GNSS receiver adapted to provide reference vertical position information for the body in said predetermined coordinate system, said GNSS receiver being configured to reduce multipath noise and to output corrected GNSS vertical position information for the body to said processor, whereby said processor determines by comparison inertial measurement errors of said inertial measurement unit and calculates a correct vertical position of the body in motion.

2. A method for determining the vertical position of a body in motion, comprising:

a. determining vertical acceleration information of a body in motion;

b. calculating, from the vertical acceleration information of said body in motion, the amount of vertical movement and vertical position of said body in motion;

c. determining a vertical reference position from at least one GNSS receiver, said GNSS receiver being configured to attenuate multipath distortions in said receiver and correct for multipath errors in determining said reference vertical position information.

3. A system for determining vertical position comprising:

a. an inertial measurement unit that includes a navigation-grade accelerometer for determining the vertical acceleration information of a body in motion;

b. a processor for determining vertical position information from said vertical acceleration information;

c. at least one global navigation satellite system receiver adapted to provide reference vertical position information of said body in motion;

d. a controller configured to reduce multipath satellite signals from said global navigation satellite system receiver, the output of said controller providing vertical position correction information to said processor for determining vertical position.

4. A system for determining vertical position comprising:

a. an inertial measurement unit for determining vertical acceleration information of a body in motion;

b. a processor for determining vertical position information from said vertical acceleration information;

c. at least one global navigation satellite system receiver adapted to provide reference vertical position information of said body in motion, said at least one receiver including one or more antennas configured to randomize multipath signals to noise; and

d. a vertical position error controller, the input to said controller being the reference vertical position information and the determined vertical position information, the output of said controller providing vertical position correction information to said processor for determining vertical position.

5. A method for determining vertical position comprising:

a. providing navigation-grade vertical acceleration information of a body in motion;

b. providing satellite-based vertical position information of the body in motion;

c. processing the vertical acceleration information of the body in motion to compute vertical position information;

d. determining the difference between said computed vertical position information and said satellite based vertical position information; and

e. employing said difference in processing the vertical acceleration information of the body in motion.

6. The method of claim 5, wherein the vertical position information of the body in motion comprises GNSS information.

7. The method of claim 6, wherein the GNSS information comprises GPS information.

8. The method of claim 7, wherein the GPS information comprises GPS vertical position information.

9. The method of claim 5, further comprising compensating the computed vertical position information for latent vertical position information.

10. The method of claim 9, further comprising subtracting the compensated computed vertical position information from said satellite based vertical position information and using a result of the subtraction to make the corrections during the processing of the vertical acceleration information.

11. The method of claim 5, wherein processing the vertical acceleration information of the body in motion to compute vertical position information comprises performing at least one integration on the vertical acceleration information.

12. The method of claim 11, wherein performing the at least one integration on the vertical acceleration information comprises integrating the vertical acceleration information to determine vertical velocity information.

13. The method of claim 12, wherein performing the at least one integration on the vertical acceleration information further comprises integrating the vertical velocity information to determine the computed vertical position information.

14. The method of claim 5, wherein the vertical acceleration information comprises at least one of inertial guidance information and odometry information.

15. The method of claim 14, wherein the at least one of inertial guidance information and odometry information comprises information from an accelerometer triad and 2-axis tilt sensor.

16. A system for determining vertical position comprising:

a. a navigation-grade accelerometer for determining vertical acceleration information of a body in motion;

b. a processor for determining vertical position information from said vertical acceleration information;

c. a satellite navigation receiver for providing reference vertical position information of said body in motion, said receiver including an antenna connected to the satellite navigation receiver configured to randomize multi-path noise; and

d. a negative feedback loop, including a filter, whose input is the difference between the reference vertical position information and the determined vertical position information, and whose output is said processor for determining vertical position information.

17. A method for determining vertical position plus or minus 1 centimeter, 2-sigma, comprising:

a. determining a vertical reference position using a satellite navigation receiver;

b. performing a first integration of the output of a navigation-grade accelerometer with respect to time;

c. using said output of the first integration as the input to a second integration with respect to time to obtain inertial vertical position;

d. delaying said inertial navigation position to account for the latency associated with said global navigation system receiver;

e. subtracting the delayed inertial position from said vertical reference position; and

f. feeding back said difference, using negative feedback, to the acceleration and velocity integrators so as to reduce the errors introduced in the acceleration and velocity integrators from said accelerometer.

18. The method of claim 17 wherein said difference between the delayed inertial position and the vertical reference position is multiplied by a first constant and subtracting from the input of said second integration.

19. The method of claim 17 wherein said difference between the delayed inertial position and the vertical reference position is multiplied by a second constant.