USRE42546EExpiredUtility
Method and system for target localization
Assignee: NEVADA ASSET LIQUIDATORS LLCPriority: Mar 27, 2002Filed: Dec 22, 2005Granted: Jul 12, 2011
Est. expiryMar 27, 2022(expired)· nominal 20-yr term from priority
G01S 3/8086
57
PatentIndex Score
4
Cited by
37
References
83
Claims
Abstract
The present inventions comprise aA method of estimating a minimum range for a target with respect to a first point of interest, independent of actual, range to the target, comprising obtaining three bearing data points; using the three bearing data points to determine a speed contribution V os cos (θ β ) of a first point of interest to a distance from a relative velocity vector over a time frame comprising t 0 to t 0 ′; determining an angle θ β as defined by the bearing relative to ownship's heading at the point in time of closest approach to a second point of interest; and calculating a minimum range using a predetermined formula.
Claims
exact text as granted — not AI-modified1. A method of estimating a minimum range from an ownship to a target at a closest point of approach (CPA) between the target and the ownship, comprising:
a.a bearing detector obtaining at least three bearing data points of the target with respect to anthe ownship, wherein each of said bearing data points includes a bearing angle and a corresponding time of acquisition;
b. using the three bearing data points to determine a speed contribution V os of a first point of interest to a distance from a relative velocity vector over a time frame comprising an initial time t o to a predetermined time t i ;
c.a computer system determining an angle θ β as defined as, where θ β is the bearing relative to the ownship's heading at the point in time (t β ) of the closest point of approach to a second point of interest; and
d.the computer system calculating a minimum range Min R CPA using the formula: Min R CPA =V OS (t β −t i )cos(θ β −θ i ) θ i |=0 ;
using the calculated minimum range for at least one of: targeting a weapon with respect to the target, navigating the ownship;
e. wherein t β is the time at which θ β was mreaured and θ i is a bearing angle to the target relative to the ownship corresponding to a first of said at least three bearing data points obtained at time t i , and V os is the speed of the ownship during said obtaining said at least three bearing data points.
2. The method of claim 1 , further comprising generating a representation of the probability of the location of the target using the calculated minimum range.
3. The method of claim 1 , wherein the calculated minimum range is further used for at least one of targeting a weapon with respect to the second point of interest, navigation of the ownship, estimating a passing range between the ownship and the second point of interest target, and avoidance of the second point of interest.
4. The method of claim 1 , wherein the at least three bearing data points are obtained passively.
5. The method of claim 1 , further comprising:
f. obtaining a fourth bearing data point of the second point with respect to an ownship;
g. calculating a further set of minimum ranges using the formula of step (d) for Min R CPA ; and
h. repeating steps (e) and (f) obtaining bearing data points and performing corresponding calculations of Min R CPA to determine a maneuvering of the second point of interest target over time.
6. The method of claim 1 , further comprising:
f. obtaining an additional plurality of bearing data points of the second point target with respect to an the ownship;
g. calculating a further set of minimum ranges using the formula of step (d) for Min R CPA ; and
h. determining a deviation of a calculated minimum range from others of the calculated minimum ranges.
7. A method for estimating a minimum range Min R CPA to a contact from an ownship, independent of actual contact range, comprising:
a. a bearing detector passively obtaining at least three bearing data points of the contact relative to an the ownship;
b. a computer system determining an angle θ β defining the bearing to the contact relative to a heading of the ownship at the point in time of closest approach to a second point of interest the contact;
c. the computer system calculating a the minimum range at CPA a closest point of approach (CPA) between the ownship and the target contact using the formula
Min R CPA =V os (t β −t i )cos(θ β −θ i ) θ i |=0 ; and
d. generating a representation of the probability of the location of the target contact located at the minimum range;
d. using the calculated minimum range to alter a heading of the ownship;
e. wherein t β is the time at which corresponding to θ β was measured, θ i is a bearing angle to the contact relative to the ownship at time t i ; and V os is a speed contribution of a first point of interest to a distance from a relative velocity vector over a time frame comprising an initial time t 0 to a predetermined time t i the ownship during said passively obtaining said at least three bearing data points.
8. The method of claim 7 , further comprising:
f. obtaining a fourth data point;
g. using the fourth data point to calculate an angle to bearing at CPA relative to the heading of the ownship;
h. calculating a time of CPA for all combinations of the three of four bearing data points; and
i. determining noise in the system by comparing a deviation in at least one of the bearing at CPA, relative to the heading of the ownship and the time of CPA for each potential solution, to a predetermined value.
9. The method of claim 8 , wherein the step of determining noise in the system further comprises determining the mean and standard deviations in the bearing calculations at CPA.
10. The method of claim 7 further comprising:
f. obtaining an estimate of a current minimum range at a time t i , the estimate comprising:
i. calculating a current minimum range R (current minimum) by dividing Min R CPA by the cosine of (θ β −θ i ) where θ 0 is a bearing relative to the ownship when θ=0, and θ i is a bearing relative to the ownship at time t i ; and
ii. generating a representation of the probability of the location of the contact.
11. The method of claim 7 , further comprising:
f. obtaining said additional bearing data points of the second point of interest contact with respect to said ownship;
g. using the additional bearing data points to refine the system noise estimate by calculating the mean and standard deviation of the bearings at CPA;
h. using the additional bearing data points to refine the mean bearing at CPA with respect to ownship's heading;
i. determining a trend of change in the mean value of bearing at CPA with respect to ownship's heading;
j. using the trend of change in the mean value of bearing at CPA with respect to ownship's heading to determine change in a relative velocity vector between said ownship and said target contact.
12. A system for calculating an estimated minimum range estimate R CPA from a source to a target, comprising:
a. a bearing detector capable of passively obtaining a bearing to the target from the source;
b. a computer having a processor and memory; and
c. range calculation software executing in the computer;
d. wherein
i. the memory stores at least three bearing data points obtained from the bearing detector;
ii. the range calculation software uses the stored three bearing data points to determine a speed contribution V os of the target to a distance from a relative velocity vector over source during a time from t 0 to t 0 ′ when said at least three bearing data points are obtained;
iii. the range calculation software determines an angle θ β defined by the bearing to the target relative to a heading of the source at the point in time of closest approach to between the source and the target;
iv. the range calculation software calculates a minimum range from the source to the targetand as Min R CPA =V OS (t β -t i )cos(θ β θ i ) θi|=0 ; and, wherein said minimum range is based in part on V os , θ β , and the point in time of closest approach; and
v. the range calculation software generates a representation of the probability of the location of a target.
wherein the system is configured to use the calculated minimum range to alter a heading of the source;
wherein the source and the target are physical objects.
13. The system of claim 12 further comprising an output device capable of reproducing a representation of at least one of the calculated minimum range output and the probability of the location of the target.
14. A method, comprising:
a. a bearing detector obtaining at least three bearing data points of a target with respect to a vehicle; b. a computer system determining an angle θ β , wherein θ β is defined as the bearing of the target relative to the vehicle's heading at the time of closest approach to the target; c. the computer system estimating a minimum range from the vehicle to the target using said obtained three bearing data points, said bearing angle θ β and a speed of the vehicle during said obtaining; and d. using said estimated minimum range to alter a heading of the vehicle.
15. The method of claim 1, further comprising using said calculated minimum range at the closest point of approach to estimate a minimum range at time t i .
16. The method of claim 15, wherein said minimum range at said time t i is equal to Min R CPA divided by cos(θ 0 −θ i ), wherein θ 0 is a bearing angle at time t 0 and θ i is a bearing angle at said time t i .
17. The method of claim 1, wherein θ β is calculated according to the following formula:
(
θ
β
)
=
tan
-
1
[
tan
(
θ
i
)
Δt
j
,
k
+
tan
(
θ
j
)
Δt
k
,
i
+
tan
(
θ
k
)
Δt
i
,
j
tan
(
θ
j
)
tan
(
θ
k
)
Δt
j
,
k
+
tan
(
θ
i
)
tan
(
θ
k
)
Δt
k
,
i
+
tan
(
θ
i
)
tan
(
θ
j
)
Δt
i
,
j
]
;
wherein θ j and θ k are bearing angles respectively corresponding to second and third ones of said at least three bearing data points, wherein θ j and θ k are obtained at times t j and t k respectively, and wherein Δt j,k , Δt k,i , Δt i,j are the differences between times t j and t k ; t k and t i ; and t i and t j , respectively.
18. The method of claim 7, further comprising using said calculated minimum range at the closest point of approach to estimate a minimum range at time t i .
19. The method of claim 18, wherein said minimum range at said time t i is equal to Min R CPA divided by cos(θ 0 −θ i ), wherein θ 0 is a bearing angle at time t 0 and θ i is a bearing angle at said time t i .
20. The method of claim 7, wherein θ β is calculated according to the following formula:
(
θ
β
)
=
tan
-
1
[
tan
(
θ
i
)
Δt
j
,
k
+
tan
(
θ
j
)
Δt
k
,
i
+
tan
(
θ
k
)
Δt
i
,
j
tan
(
θ
j
)
tan
(
θ
k
)
Δt
j
,
k
+
tan
(
θ
i
)
tan
(
θ
k
)
Δt
k
,
i
+
tan
(
θ
i
)
tan
(
θ
j
)
Δt
i
,
j
]
;
wherein θ j and θ k are bearing angles respectively corresponding to second and third ones of said at least three bearing data points, wherein θ j and θ k are obtained at times t j and t k respectively, and wherein Δt j,k , Δt k,i , Δt i,j are the differences between times t j and t k ; t k and t i ; and t i and t j , respectively.
21. A method for tracking a second point of interest relative to a first point of interest, said method comprising:
a computer system receiving information indicative of at least three bearing data points of said second point of interest relative to said first point of interest, wherein each of the at least three bearing data points includes a bearing angle and a corresponding acquisition time, wherein each acquisition time is different; the computer system estimating a minimum range of said second point of interest relative to said first point of interest, wherein said estimating uses one or more equations, wherein said one or more equations have a closed-form solution, and wherein at least one of said one or more equations is based in part upon three of said at least three bearing data points; and altering a heading of the first point of interest based at least in part on the estimated minimum range; wherein the first and second points of interest are physical objects.
22. The method of claim 21, wherein at least one of said one or more equations is also based in part on a speed of said first point of interest.
23. The method of claim 22, wherein said estimated minimum range corresponds to a closest point of approach (CPA) between the first and second points of interest.
24. The method of claim 23, further comprising using said estimated minimum range corresponding to said CPA to estimate a minimum range at a time t i .
25. The method of claim 24, wherein said minimum range at said time t i is equal to said minimum range corresponding to said CPA divided by cos(θ 0 −θ i ), wherein θ 0 is a bearing angle at a time t 0 and θ i is a bearing angle at said time t i .
26. The method of claim 23, wherein said estimating said minimum range includes estimating a bearing angle θ β at the CPA.
27. The method of claim 26, wherein said estimating θ β is based in part upon said at least three bearing data points.
28. The method of claim 26, wherein θ β is calculated using the following equation:
(
θ
β
)
=
tan
-
1
[
tan
(
θ
i
)
Δt
j
,
k
+
tan
(
θ
j
)
Δt
k
,
i
+
tan
(
θ
k
)
Δt
i
,
j
tan
(
θ
j
)
tan
(
θ
k
)
Δt
j
,
k
+
tan
(
θ
i
)
tan
(
θ
k
)
Δt
k
,
i
+
tan
(
θ
i
)
tan
(
θ
j
)
Δt
i
,
j
]
;
wherein θ j and θ k are bearing angles respectively corresponding to second and third ones of said at least three bearing data points, wherein θ j and θ k are obtained at times t j and t k respectively, and wherein Δt j,k , Δt k,i , Δt i,j are the differences between times t j and t k ; t k and t i ; and t i and t j , respectively.
29. The method of claim 23, wherein the estimation of said minimum range is based upon a time t β corresponding to the CPA.
30. The method of claim 21, wherein said minimum range (Min R CPA ) corresponds to a closest point of approach (CPA) between the first and second points of interest, and wherein Min R CPA is calculated according to the formula Min R CPA =V os (t β −t i )cos(θ β −θ i ) θi|=0 , and wherein V os is a speed of said first point of interest, θ i is a bearing angle between the first point of interest and the second point of interest at time t i , and θ β is a bearing angle between the first point of interest and the second point of interest at time t β , wherein t β is an estimated time corresponding to the CPA.
31. The method of claim 21, wherein said at least three bearing data points include four or more bearing data points, the method further comprising estimating a minimum range corresponding to each three data point-combination of the four or more bearing data points.
32. The method of claim 31, further comprising performing a statistical analysis on each of said estimated minimum ranges.
33. The method of claim 32, wherein said statistical analysis includes calculating a mean minimum range.
34. The method of claim 32, wherein said statistical analysis includes calculating a standard deviation of said estimated minimum range.
35. The method of claim 21, wherein said receiving includes receiving four or more bearing data points, the method further comprising using the received four or more data points to detect the presence of noise.
36. The method of claim 21, wherein said receiving includes receiving five or more bearing data points, the method further comprising using the received five or more data points to detect maneuvering of said second point of interest.
37. The method of claim 21, wherein said first point of interest is a water vessel.
38. The method of claim 21, wherein said second point of interest is a water vessel.
39. The method of claim 21, wherein said first point of interest is in motion, and said second point of interest is stationary.
40. The method of claim 21, wherein the one or more equations include the following mathematical operations: addition, subtraction, multiplication, division, cosine, tangent, inverse tangent.
41. The method of claim 21, further comprising using said estimated minimum range to launch a weapon at said second point of interest.
42. A method for tracking a second point of interest relative to a first point of interest, said method comprising:
a computer system receiving information indicative of at least three bearing data points, wherein each of said at least three bearing data points includes a bearing angle and a corresponding acquisition time, wherein each bearing angle is measured between a heading of said first point of interest and the second point of interest at said corresponding acquisition time, wherein each said corresponding acquisition time is different; the computer system estimating a minimum range of said second point of interest relative to said first point of interest, wherein said estimating is performed in a single iteration through a set of one or more equations, wherein said set of equations are based in part upon three of said at least three bearing data points; and altering a heading of the first point of interest based at least in part on the estimated minimum range; wherein the first and second points of interest are physical objects.
43. The method of claim 42, wherein said set of equations are based in part upon a speed of the first point of interest.
44. The method of claim 42, wherein said at least three bearing data points is a number (N) of bearing data points greater than or equal to four, said method further comprising performing a number (C) of minimum range calculations for each three data point-combination of said N bearing data points, where C=N!/((N−3)!*3!), wherein each of said C minimum range calculations is performed in a single iteration through said set of equations.
45. The method of claim 42, further comprising computing a mean minimum range from said C minimum range calculations.
46. The method of claim 42, further comprising computing a standard deviation of said C minimum range calculations.
47. The method of claim 42, wherein either or both of said first and second points of interest are water vessels.
48. The method of claim 42, wherein said set of equations is based in part upon an angle between a heading of said first point of interest and said second point of interest at a closest point of approach between said first and second points of interest.
49. The method of claim 42, further comprising using said estimated minimum range to alter a heading of said first point of interest.
50. The method of claim 42, further comprising using said estimated minimum range to launch a weapon at said second point of interest.
51. The method of claim 42, wherein said minimum range corresponds to a closest point of approach between said first and second point of interest.
52. The method of claim 42, further comprising using said minimum range at said closest point of approach to calculate a minimum range at a different time.
53. A system, comprising:
a processor; and a memory coupled to the processor, wherein the memory is configured to store program instructions executable by the processor to:
receive at least three bearing data points of a second point of interest relative to a first point of interest, wherein each of the at least three bearing data points includes a bearing angle and a corresponding acquisition time, wherein each bearing angle is an angle between a heading of said first point of interest and a second point of interest at said corresponding acquisition time, wherein each acquisition time is different, and wherein said first and second points of interest are physical objects; and
estimate a minimum range of said second point of interest relative to said first point of interest, wherein said estimation uses one or more equations, wherein said one or more equations have a closed-form solution, and wherein at least one of said one or more equations is based in part upon three of said at least three bearing data points;
wherein said system is further configured to use said estimated minimum range to alter a heading of said first point of interest.
54. The system of claim 53, further comprising one or more bearing detectors configured to obtain bearing data points.
55. The system of claim 54, wherein said bearing detectors are configured to obtain said bearing data points passively.
56. The system of claim 53, wherein the one or more equations include the following mathematical operations: addition, subtraction, multiplication, division, cosine, tangent, inverse tangent.
57. The system of claim 53, wherein said system is further configured to use said estimated minimum range to target said second point of interest using a weapons system configured to target said second point of interest.
58. The system of claim 53, wherein said estimated minimum range corresponds to a closest point of approach (CPA) between said first and second points of interest, and wherein said system is further configured to use said estimated minimum range in order to estimate a minimum range at a time other than a time corresponding to said CPA.
59. A system, comprising:
a processor; and a memory coupled to the processor, wherein the memory is configured to store program instructions executable by the processor to:
receive at least three bearing data points of a second point of interest relative to a first point of interest, wherein said data points are acquired at different times, and wherein said first and second points of interest are physical objects; and
estimate a minimum range of said second point of interest relative to said first point of interest, wherein said estimating is performed in a single iteration through a set of one or more equations, wherein said set of equations are based in part upon three of said at least three bearing data points;
wherein said system is further configured to use said estimated minimum range to target said second point of interest with a weapons system.
60. The system of claim 59, wherein each of the at least three bearing data points includes a bearing angle and a corresponding acquisition time.
61. The system of claim 59, further comprising one or more bearing detectors configured to obtain bearing data points.
62. The system of claim 59, wherein the number of said at least three bearing data points is a number (N) greater than or equal to four, said method further comprising performing a number (C) of minimum range calculations for each three data point-combination of said N bearing data points, where C=N!/((N−3)!*3!), wherein each of said C minimum range calculations is performed in a single iteration through said set of equations.
63. The system of claim 59, wherein said system is further configured to use said estimated minimum range to alter a heading of said first point of interest.
64. A non-transitory computer readable medium comprising program instructions, wherein the instructions are computer-executable to:
receive at least three bearing data points of a second point of interest relative to a first point of interest, wherein each of the at least three bearing data points includes a bearing angle and a corresponding acquisition time, wherein each acquisition time is different; estimate a minimum range of said second point of interest relative to said first point of interest, wherein said estimation uses one or more equations, wherein said one or more equations have a closed-form solution, and wherein said one or more equations are based in part upon three of said at least three bearing data points; and use said estimated minimum range to alter a heading of said first point of interest; wherein said first and second points of interest are physical objects.
65. The non-transitory computer readable medium of claim 64, wherein the one or more equations include the following mathematical operations: addition, subtraction, multiplication, division, cosine, tangent, inverse tangent.
66. A non-transitory computer readable medium comprising program instructions, wherein the instructions are computer executable to:
receive at least three bearing data points of a second point of interest relative to a first point of interest, wherein each of said data points corresponds to different points in time, and wherein said first and second points of interest are physical objects; calculate an estimation of a minimum range of said second point of interest relative to said first point of interest, wherein said estimation is performed in a single iteration through one or more equations, wherein said one or more equations depend in part upon three of said at least three bearing data points; and use said estimated minimum range to target said second point of interest with a weapons system.
67. A method, comprising:
a computer system receiving information indicative of at least three bearing data points, wherein each of the at least three bearing data points includes a bearing angle and a corresponding acquisition time, wherein each bearing angle is measured between a heading of a first point of interest and a second point of interest, and wherein each acquisition time is different; the computer system estimating a minimum range of said second point of interest relative to said first point of interest, wherein said estimating is based on one or more equations having a closed-form solution, and wherein said one or more equations are based in part upon three of said at least three bearing data points; and using said estimated minimum range to change a heading of said first point of interest; wherein said first point of interest and said second point of interest are physical objects, and wherein said first point of interest is a vehicle.
68. The method of claim 67, wherein said first point of interest is an automobile.
69. The method of claim 67, wherein said first point of interest is a water vessel.
70. The method of claim 67, wherein said first point of interest is an aircraft.
71. The method of claim 67, wherein said estimation of said minimum range is based in part upon a bearing angle θ β that corresponds to a closest point of approach (CPA) between said first and second points of interest.
72. The method of claim 67, wherein said bearing angle θ β at the CPA is calculated according to the following formula:
(
θ
β
)
=
tan
-
1
[
tan
(
θ
i
)
Δt
j
,
k
+
tan
(
θ
j
)
Δt
k
,
i
+
tan
(
θ
k
)
Δt
i
,
j
tan
(
θ
j
)
tan
(
θ
k
)
Δt
j
,
k
+
tan
(
θ
i
)
tan
(
θ
k
)
Δt
k
,
i
+
tan
(
θ
i
)
tan
(
θ
j
)
Δt
i
,
j
]
;
wherein θ j and θ k are bearing angles respectively corresponding to second and third ones of said at least three bearing data points, wherein θ j and θ k are obtained at times t j and t k respectively, and wherein Δt j,k , Δt k,i , Δt i,j are the differences between times t j and t k ; t k and t i ; and t i and t j , respectively.
73. The method of claim 67, wherein said estimated minimum range corresponds to a closest point of approach (CPA) between said first and second points of interest, and wherein said method further comprises using said estimated minimum range at said CPA to estimate a minimum range at a time t i .
74. The method of claim 73, wherein said minimum range at said time t i is equal to said minimum range at said CPA divided by cos(θ 0 −θ i ), wherein θ 0 is a bearing angle at time t 0 and θ i is a bearing angle at said time t i .
75. A method, comprising:
a computer system receiving information indicative of at least three bearing data points, wherein each of the at least three bearing data points includes a bearing angle and a corresponding acquisition time, wherein each bearing angle is measured between a heading of a first point of interest and a second point of interest, and wherein each acquisition time is different, and wherein said first and second points of interest are physical objects; the computer system estimating a minimum range of said second point of interest relative to said first point of interest, wherein said estimating is based on one or more equations having a closed-form solution, and wherein said one or more equations are based in part upon three of said at least three bearing data points; and targeting said second point of interest using a weapons system, wherein said targeting is based in part upon said estimated minimum range.
76. The method of claim 75, wherein said first point of interest is a water vessel.
77. The method of claim 75, wherein said estimation of said minimum range is based in part upon a bearing angle θ β that corresponds to a closest point of approach (CPA) between said first and second points of interest.
78. The method of claim 77, wherein said bearing angle θ β at the CPA is calculated according to the following formula:
(
θ
β
)
=
tan
-
1
[
tan
(
θ
i
)
Δt
j
,
k
+
tan
(
θ
j
)
Δt
k
,
i
+
tan
(
θ
k
)
Δt
i
,
j
tan
(
θ
j
)
tan
(
θ
k
)
Δt
j
,
k
+
tan
(
θ
i
)
tan
(
θ
k
)
Δt
k
,
i
+
tan
(
θ
i
)
tan
(
θ
j
)
Δt
i
,
j
]
;
wherein θ j and θ k are bearing angles respectively corresponding to second and third ones of said at least three bearing data points, wherein θ j and θ k are obtained at times t j and t k respectively, and wherein Δt j,k , Δt k,i , Δt i,j are the differences between times t j and t k ; t k and t i ; and t i and t j , respectively.
79. The method of claim 75, wherein said estimated minimum range corresponds to a closest point of approach (CPA) between said first and second points of interest, and wherein said method further comprises using said estimated minimum range at said CPA to estimate a minimum range at a time t i .
80. The method of claim 75, wherein said minimum range at said time t i is equal to said minimum range at said CPA divided by cos(θ 0 −θ i ), wherein θ 0 is a bearing angle at time t 0 and θ i is a bearing angle at said time t i .
81. The method of claim 14, wherein the vehicle is an aircraft, a water vessel, or an automobile.
82. The method of claim 67, wherein the second point of interest is another vehicle.
83. The method of claim 67, wherein the second point of interest is a stationary object.Join the waitlist — get patent alerts
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