US5216236A
Expired / Lapsed
US
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Optical tracking system
Assignee: National Research Council Canada
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Filing: 1992-01-15
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Granted: 1993-06-01
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Expires: 2012-01-15
Abstract
Abstract An optical system for tracking a target scans an optical beam across the target in a Lissajous pattern. The pattern has at least one portion that extends across the target. Return signals reflected from the target are used to calculate the range (and, if desired, also the intensity) of each measured point on the target (and beyond the target if some portions of the pattern miss the target), and to calculate the deviation of a reference location on the pattern, e.g. its center, from a selected location of the target. This deviation is used to correct the scan to move the reference location on the pattern towards the selected location on the target, thus tracking the target. The amplitude of the pattern can be changed to adjust the pattern on the target or to search for a target. By virtue of the range data obtainable for points on the target and on edges of the target, the system can also determine other features, such as the shape, profile, identity and attitude of the target.
Inventors
- 👤 Francois Blais
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 22:20
CPC Classifications
G; G01; G01S; G01S17/00; G01S17/02; G01S17/06; G01S17/42; G01S17/66
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
136 words
An optical tracking system comprising means for transmitting an outgoing optical beam towards a target and for receiving a return optical signal reflected by a point on the target, including means for measuring the range of said target point, characterized by a) means for scanning said beam in a Lissajous pattern of such shape and amplitude that at least one portion of the pattern extends across the target, b) means for calculating from separate return optical signals received respectively from at least three individual points on the target a deviation of a reference location on the pattern from a selected location on the target, and c) means for applying said deviation to the scanning means to modify the position of the pattern to move said reference location towards said selected location and hence track the target.
Claim 2
Dependent Claim
136 words
An optical tracking system comprising means for transmitting an outgoing optical beam towards a target and for receiving a return optical signal reflected by a point on the target, including means for measuring the range of said target point, characterized by a) means for scanning said beam in a Lissajous pattern of such shape and amplitude that at least one portion of the pattern extends across the target, b) means for calculating from separate return optical signals received respectively from at least three individual points on the target a deviation of a reference location on the pattern from a selected location on the target, and c) means for applying said deviation to the scanning means to modify the position of the pattern to move said reference location towards said selected location and hence track the target.
Claim 3
Dependent Claim
30 words
A system according to claim 1, wherein portions of the pattern extend beyond edges of the target, said at least three points being located at the edges of the target.
Claim 4
Dependent Claim
34 words
A system according to claim 2, wherein the calculating means includes means for measuring the profile of the target form the measured ranges of a number of points on the edges of the target.
Claim 5
Dependent Claim
36 words
A system according to claim 3, wherein the calculating means includes means for comparing the measured target profile with data on the profiles of known objects to enable the target and its attitude to be identified.
Claim 6
Dependent Claim
21 words
A system according to claim 1, wherein the Lissajous pattern is a symmetrical one generated by two sine or cosine waves.
Claim 7
Dependent Claim
31 words
A system according to claim 5, wherein the frequencies of the two waves have a ratio to each other selected from 1:1, 1:2, 1:3, 2:3, 3:4, 3:5, 4:5, 5:6, 6:7, 7:8.
Claim 8
Dependent Claim
16 words
A system according to claim 1, including means for varying the amplitude of the Lissajous pattern.
Claim 9
Dependent Claim
120 words
A system according to claim 1, wherein said scanning means comprise d) means for generating a first sine or cosine wave output of a first frequency, e) means for generating a second sine or cosine wave output of a second frequency, the relationship between these frequencies being such as to generate a Lissajous pattern, and f) means controlled by said first and second wave outputs for oscillating respective mirrors about axes perpendicular to each other, said mirrors being located in the paths of the outgoing beam and of the return signals, g) said means for applying the deviation to the scanning means including offset means for applying said components of the deviation respectively to said first and second wave outputs.
Claim 10
Dependent Claim
34 words
A system according to claim 1, including means for measuring the intensity of a return optical signal reflected by a point on the target to provide additional data on the nature of the target.
Claim 11
Dependent Claim
32 words
A system according to claim 1, wherein the calculating means includes means for measuring the surface shape of the target from the measured ranges of a number of points on the target.
Claim 12
Dependent Claim
36 words
A system according to claim 10, wherein the calculating means includes means for comparing the measured target shape with data on the shapes of known objects to enable the target and its attitude to be identified.
Claim 13
Dependent Claim
135 words
An optical method of tracking a target comprising transmitting an outgoing optical beam towards a target and receiving a return optical signal reflected by a point on the target, including measuring the range of said target point, said method being characterized by a) scanning said beam in a Lissajous pattern of such shape and amplitude that at least one portion of the pattern extends across the target, b) calculating from at least three separate return optical signals reflected respectively by at least three individual said points on the target a deviation of a reference location on the pattern from a selected location on the target, and c) applying said deviation to the scanning means to modify the position of the pattern to move said reference location towards said selected location and hence track the target.
Claim 14
Dependent Claim
135 words
An optical method of tracking a target comprising transmitting an outgoing optical beam towards a target and receiving a return optical signal reflected by a point on the target, including measuring the range of said target point, said method being characterized by a) scanning said beam in a Lissajous pattern of such shape and amplitude that at least one portion of the pattern extends across the target, b) calculating from at least three separate return optical signals reflected respectively by at least three individual said points on the target a deviation of a reference location on the pattern from a selected location on the target, and c) applying said deviation to the scanning means to modify the position of the pattern to move said reference location towards said selected location and hence track the target.
Claim 15
Dependent Claim
32 words
A method according to claim 12, including measuring the intensity of a return optical signal reflected by a point on the target to provide additional data on the nature of the target.
Claim 16
Dependent Claim
26 words
A method according to claim 12, including measuring the surface shape of the target from the measured ranges of a number of points on the target.
Claim 17
Dependent Claim
30 words
A method according to claim 14, including comparing the measured target shape with data on the shapes of known objects to enable the target and its attitude to be identified.
Claim 18
Dependent Claim
27 words
A method according to claim 12, including measuring the profile of the target from the measured ranges of a number of points on edges of the target.
Claim 19
Dependent Claim
30 words
A method according to claim 16, including comparing the measured target profile with data on the profiles of known objects to enable the target and its attitude to be identified.
Claim 20
Dependent Claim
41 words
A method according to claim 12, wherein the Lissajous pattern is a symmetrical one generated by two sine or cosine waves of frequencies having a ratio to each other selected from 1:1, 1:2, 1:3, 2:3, 3:4, 3:5, 4:5, 5:6, 6:7, 7:8.
Claim 21
Dependent Claim
23 words
A method according to claim 12, including initially searching for a target to be tracked by varying the amplitude of the Lissajous pattern.
Claim 22
Dependent Claim
27 words
A method according to claim 12, including simultaneously tracking at least one other target by scanning each target alternately using a different Lissajous pattern for each target.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-05-31 | 1996-11-30 | 1997-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-05-31 | 2000-11-30 | 2001-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-05-31 | 2004-11-30 | 2005-06-01 | $7700.00 | Window Closed / Lapsed |