AINS land surveyor system with reprocessing, AINS-LSSRP

• US 20020111717A1
• Filed: 11/14/2001
• Published: 08/15/2002
• Est. Priority Date: 11/22/2000
• Status: Active Grant

• Current Assignee: Applanix Corp. (Trimble Inc.)
• Original Assignee: Applanix Corp. (Trimble Inc.)
• Inventors: Scherzinger, Bruno, Lithopoulos, Erik, Reid, Blake
• Granted Patent: US 6,834,234 B2
• Time in Patent Office: Days
• US Class Current: 701/1
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments

Abstract

A Land Surveyor System with Reprocessing is carried by a surveyor moving from a first known position at the start of a survey interval to a second known position at the end of the survey interval has an AINS (aided inertial navigation system) that provides a continuing sequence of time-indexed present position values. A Position Computing System uses a program that stores the sequence of time-indexed present position values in a memory. A reprocessing computer and program is activated at the second known position to access and process the continuing sequence of time-indexed present position values with a smoothing program to provide indexed and adjusted present position values for at least some of the time-indexed present position values. The system is packaged for transport and use by a surveyor. A switch permits the surveyor to signal that the unit is stationary as a reset for the AINS.

Claims

1. A Land Surveyor System with Reprocessing (LSSRP) comprising:

an AINS providing a sequence time-indexed present position values in response to the LSSRP being moved from a first known position value at the start of a survey interval to a second known position value at the end of the survey interval,

a Position Computing System (PCS) coupled to receive and store the sequence of time-indexed present position values as the surveyor moves from the first known position to the second known position, the PCS having,

a reprocessing computer and program means for processing the indexed present position values with a smoothing algorithm to provide indexed and adjusted present position values for at least some of the indexed present position values, between the first known position value at the start of the survey interval and the second known position value at the end of the survey interval.

2. The LSSRP of claim 1 wherein the AINS uses a Kalman filter responsive to at least two sources of aiding signals,

the PCS having an aiding signal selector algorithm characterized to select the most accurate aiding signal for use by the Kalman filter from all available aiding signals.

3. The LSSRP of claim 1 wherein the reprocessing computer and program means smoothing algorithm is a Modified Bryson-Frazier smoother (MBFS).

4. The LSSRP of claim 1 wherein the reprocessing computer and program means smoothing algorithm is a modified Bryson-Frazier smoother (MBFS) mechanized using the following equations and definitions for steps and definitions:

data available to the MBFS at iteration k from the AINS-LSSRP Kalman filter;

Φ

(k;

k−

1) transition matrix from iteration k−

1 to iteration k,

H_k measurement matrix,

K_k Kalman gain,

S_k Kalman innovations covariance,

{right arrow over (ξ

)}_k innovations vector,

{right arrow over ({circumflex over (x)})}_k⁻

, {right arrow over ({circumflex over (x)})}_k⁺ Kalman estimated error state,

P_k⁻

, P_k⁺ Kalman generated estimation error VCV matrix, and where,

the backwards extrapolation follows;

{right arrow over (λ

)}<sub>k−

1</sub>⁺=Φ

^T(k;

k−

1){right arrow over (λ

)}_k⁻

, 

 

(12)Λ

<sub>k−

1</sub>⁺=Φ

^T(k;

k−

1)Λ

_k⁻

Φ

(k;

k−

1), 

 

(13)

and the adjoint measurement update follows;

{right arrow over (λ

)}_k⁻

=(I−

H_kK_k){right arrow over (λ

)}_k⁺−

H_kS_k<sup>−

1</sup>{right arrow over (ξ

)}_k, 

 

(15)Λ

_k⁻

=(I−

H_kK_k)^TΛ

_k⁺(I−

H_kK_k)+H_k^TS_kH_k, 

 

(14)

and where;

{right arrow over (λ

)}_k⁻

is the a priori adjoint state vector,

Λ

_k⁻

is the a priori adjoint VCV matrix,

{right arrow over (λ

)}_k⁺ is the a posteriori state vector, and

{right arrow over (λ

)}_k⁺ is the a posteriori adjoint VCV matrix;

and where;

the smoothed state and estimation error VCV matrix is defined by;

{right arrow over (x)}_k^s={right arrow over (x)}_k⁻

−

P_k⁻

{right arrow over (λ

)}_k⁻

={right arrow over (x)}_k⁺P_k⁺{right arrow over (λ

)}_k⁺, 

 

(16)P_k^s=P_k⁻

(I−

Λ

_k⁻

P_k⁻

)=P_k⁺(I−

Λ

_k⁺P_k⁺), 

 

(17)

and where the smoothed state vector is defined by;

$\begin{array}{cc}{\stackrel{\rightharpoonup <br><br>}{x}}_k^s=\left[\begin{array}{c}\mathrm{\delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\stackrel{\rightharpoonup <br><br>}{r}}_s\\ {\stackrel{\rightharpoonup <br><br>}{x}}_{\mathrm{remaining}}^s\end{array}\right]& \left(19\right)\end{array}$

where δ

{right arrow over (r)}_s is the smoothed estimate of AINS position error and

{right arrow over (x)}_remaining^s is the sub-vector of smoothed error states other than δ

{right arrow over (r)}_s

and where the AINS position vector {right arrow over (r)}_sk^e is obtained from the error correction difference matrix (20) using earth fixed Cartesian coordinates (X, Y, Z components) as

$\begin{array}{cc}{\stackrel{\rightharpoonup <br><br>}{r}}_{s_k}^e={\stackrel{\rightharpoonup <br><br>}{r}}_k^e-\mathrm{\delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\stackrel{\rightharpoonup <br><br>}{r}}_s=\left[\begin{array}{c}{\hat{r}}_x^e-\mathrm{\delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\hat{r}}_{s_x}^e\\ {\hat{r}}_y^e-\mathrm{\delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\hat{r}}_{s_y}^e\\ {\hat{r}}_z^e-\mathrm{\delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\hat{r}}_{s_z}^e\end{array}\right].& \left(20\right)\end{array}$

5. The LSSRP of claim 1 wherein the PCS and the AINS are integrally coupled into a package to be carried by a surveyor and wherein the package further comprises an input/output interface device having a means for inputting and time-indexing successive known present position values at respective successive known present position fixes, each successive pair of known present position values establishing the beginning and end of a survey interval, and for signaling the reprocessing computer and program means to run the smoother algorithm using the successive known present position fixes with the indexed present position values obtained during the corresponding past survey interval to provide indexed and adjusted present position values for at least some of the indexed present position values.

6. The LSSRP of claim 5 wherein the input/output interface device having a means for inputting and time-indexing successive known present position values further comprises:

a computer key pad and a read-out display electrically coupled to the PCS for inputting successive known present position values and signaling the start of a position fix.

7. The LSSRP of claim 1 wherein the PCS coupled to receive and store the sequence of time-indexed present position values further comprises:

a mass storage memory for storing the sequence of time-indexed present position values.

8. The LSSRP of claim 7 wherein the mass storage memory for storing the sequence of time-indexed present position values is linked to the reprocessing computer and program mean by a radio link.

9. The LSSRP of claim 1 wherein the PCS and the AINS are integrally coupled into a package for transport and use by a surveyor, the PCS having a switch means with which the surveyor manually signals the AINS that the unit is stationary and that a ZUPD has started.

10. The LSSRP of claim 9 wherein the switch means further comprises a mechanical closure coupled to the package and electrically coupled to the AINS to signal the start of a ZUPD, the mechanical closure being transferred by operation of a lever or plunger contacting the ground.

11. A Land Surveyor System with Reprocessing (LSSRP) transported by a surveyor moving from a first known position at the start of a survey interval to a second known position at the end of the survey interval, the LSSRP comprising:

an Aided Inertial Navigation System (AINS) having a Kalman filter coupled to be responsive to at least a first source of aiding time-indexed values, the AINS providing a continuing sequence of time-indexed present position values,

a Position Computing System (PCS) having a program for storing the continuing sequence of time-indexed present position values in a memory and for outputting the time-indexed present position value of the PCS as the surveyor moves from the first known position to the second known position, the surveyor using the output time-indexed present position value to locate at least one predetermined stake position,

the PCS further comprising a reprocessing computer and program means activated at the second known position to access and process the stored continuing sequence of time-indexed present position values with a smoothing program to provide indexed and adjusted present position values for at least some of the continuing sequence of time-indexed present position values, and wherein,

the PCS and the AINS are integrally coupled into a package for transport and use by a surveyor, the PCS having a switch means for signaling the AINS that the unit is stationary and that a ZUPD has started.

12. The LSSRP of claim 11 wherein the PCS further comprises an aiding signal selector for analyzing the aiding position signals available to the AINS and for commanding the AINS to select and use the highest accuracy aiding position signal available.

13. The LSSRP of claim 12 wherein the aiding signal selector for analyzing the aiding position signals available to the AINS monitors for loss of differential GPS and in the event differential GPS is lost, the aiding signal selector directs the AINS to not use GPS signals as aiding position signals until differential GPS is restored.

14. The LSSRP of claim 12 wherein the aiding signal selector is further characterized to receive all aiding position signals and to select and the highest accuracy aiding position signal for use provide the highest accuracy aiding position signal to the AINS for use as an input to a Kalman filter.

15. The LSSRP of claim 11 wherein the smoothing program to provide indexed and adjusted present position values for at least some of the continuing sequence of time-indexed present position values is a Modified Bryson-Frazier smoother (MBFS).

16. The LSSRP of claim 11 wherein the PCS further comprises:

a mass storage memory for storing the sequence of time-indexed present position values in an array of memory locations for later recall.

17. The LSSRP of claim 11 wherein the PCS and AINS package further comprises a switch means with which the surveyor manually signals the AINS that the unit is stationary and that a ZUPD has started.

19. The LSSRP process of claim 18 wherein the step of providing an AINS further comprises the steps of:

providing at least two sources of aiding signals to a Kalman filter in the AINS,

providing an aiding signal selector, the aiding signal selector running an algorithm characterized to select the most accurate aiding signal for use by the Kalman filter from all available aiding signals.

20. The LSSRP of process of claim 18 further comprising the step of programming the reprocessing computer and program means to run a smoothing algorithm program,

the program processing the indexed present position values to provide indexed and adjusted present position values for at least some of the indexed present position values.

18. A Land Surveyor System with Reprocessing (LSSRP) process comprising the steps of:

providing an AINS and programming the AINS to provide a sequence time-indexed present position values in response to the LSSRP being moved from a first known position value at the start of a survey interval to a second known position value at the end of the survey interval,

providing a Position Computing System (PCS) and directing and coupling the PCS to receive and store the sequence of time-indexed present position values as the surveyor moves from the first known position to the second known position,

providing a reprocessing computer and running a reprocessing program to process the indexed present position values with a smoothing algorithm,

providing indexed and adjusted present position values for at least some of the indexed present position values to correct the position of at least one stake, between the first known position value at the start of the survey interval and the second known position value at the end of the survey interval.